fix(parser): WASM scratch layout and scan cache for chunked parse

Place parser state above the linked transition table so scans emit ops
correctly, and preserve or clear the WASM scan cache across nested and
reused parse buffers.

Co-authored-by: Cursor <cursoragent@cursor.com>

.agents/skills/benchmark/SKILL.md

@@ -0,0 +1,28 @@
+---
+name: benchmark
+description: Run and author benchmark tests in xterm.js. Use when editing benchmark files, working in `*.benchmark.ts`, or when asked how to run the full benchmark suite, a single benchmark file, or a single benchmark case.
+---
+
+# Benchmark Run Instructions
+
+## Running Benchmarks
+
+- Full suite: `npm run benchmark`
+- Single benchmark file:
+  - Tree: `npm run benchmark -- -t out-test/benchmark/Event.benchmark.js`
+  - Run file: `npm run benchmark -- -s "out-test/benchmark/Event.benchmark.js" out-test/benchmark/Event.benchmark.js`
+- Single context/case:
+  - Use `-t` to get the path, then:
+  - `npm run benchmark -- -s "<path>" out-test/benchmark/Event.benchmark.js`
+
+## Benchmark Case Selection
+
+When writing benchmark instructions:
+
+- Use `RuntimeCase` to measure pure runtime in ms.
+- Use `ThroughputRuntimeCase` when measuring throughput in MB/s.
+
+## Notes
+
+- Benchmarks run from built JS in `out-test/benchmark/*.benchmark.js`.
+- Benchmark sources import compiled modules from `../../out/common/` and `../../out/browser/` (run `npm run build` first).

.agents/skills/unit-test/SKILL.md

@@ -1,7 +1,11 @@
 ---
-applyTo: '**/*.test.ts'
+name: unit-test
+description: Write and review xterm.js unit tests with project conventions. Use when editing `*.test.ts` files or when asked for test authoring guidelines.
 ---
-When writing unit tests follow these rules:
+
+# Unit Test Instructions
+
+When writing unit tests, follow these rules:
 
 - When writing unit tests for addons, always create a real xterm.js instance instead of mocking it.
 - Prefer `assert.ok` over `assert.notStrictEqual` when checking something is undefined or not.

.github/instructions/benchmark.instructions.md

@@ -1,18 +0,0 @@
----
-applyTo: '**/*.benchmark.ts'
----
-# Benchmark run instructions
-
-- Full suite: `npm run benchmark`
-- Single benchmark file:
-  - Tree: `npm run benchmark -- -t out-test/benchmark/Event.benchmark.js`
-  - Run file: `npm run benchmark -- -s "out-test/benchmark/Event.benchmark.js" out-test/benchmark/Event.benchmark.js`
-- Single context/case:
-  - Use `-t` to get the path, then:
-  - `npm run benchmark -- -s "<path>" out-test/benchmark/Event.benchmark.js`
-
-When writing instructions, use `RuntimeCase` to measure pure runtime in ms, use `ThroughputRuntimeCase` when measuring throughput in MB/s.
-
-Notes:
-- Benchmarks run from built JS in `out-test/benchmark/*.benchmark.js`.
-- Keep `NODE_PATH=./out` (handled by the npm script).

.github/workflows/ci.yml

@@ -207,31 +207,31 @@ jobs:
     - name: Build demo server
       run: npm run esbuild-demo-server
     - name: Integration tests (core) # Tests use 50% workers to reduce flakiness
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=core
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=core
     - name: Integration tests (addon-attach)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-attach
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-attach
     - name: Integration tests (addon-clipboard)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-clipboard
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-clipboard
     - name: Integration tests (addon-fit)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-fit
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-fit
     - name: Integration tests (addon-image)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-image
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-image
     - name: Integration tests (addon-progress)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-progress
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-progress
     - name: Integration tests (addon-search)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-search
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-search
     - name: Integration tests (addon-serialize)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-serialize
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-serialize
     - name: Integration tests (addon-unicode-graphemes)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-unicode-graphemes
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-unicode-graphemes
     - name: Integration tests (addon-unicode11)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-unicode11
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-unicode11
     - name: Integration tests (addon-web-fonts)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-web-fonts
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-web-fonts
     - name: Integration tests (addon-web-links)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-web-links
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-web-links
     - name: Integration tests (addon-webgl)
-      run: npm run test-integration-${{ matrix.browser }} --workers=50% --forbid-only --suite=addon-webgl
+      run: npm run test-integration-${{ matrix.browser }} -- --workers=50% --forbid-only --suite=addon-webgl
 
   release-dry-run:
     needs: build

.gitignore

@@ -17,11 +17,16 @@ docs/
 npm-debug.log
 /.idea/
 .env
+mise.toml
 build/
 .DS_Store
 yarn.lock
 test-results/
 
+# Tracing/debug files
+.cursor/nal-trace/
+.cursor/*.log
+
 # Keep bundled code out of Git
 dist/
 demo/dist/

.oxlintrc.json

@@ -0,0 +1,372 @@
+{
+  "$schema": "./node_modules/oxlint/configuration_schema.json",
+  "plugins": [
+    "typescript"
+  ],
+  "categories": {
+    "correctness": "off"
+  },
+  "options": {
+    "typeAware": true,
+    "maxWarnings": 0
+  },
+  "env": {
+    "builtin": true
+  },
+  "ignorePatterns": [
+    "addons/*/src/third-party/*.ts",
+    "**/out/*",
+    "**/out-test/*",
+    "**/out-esbuild/*",
+    "**/out-esbuild-test/*",
+    "**/inwasm-sdks/*",
+    "**/typings/*.d.ts",
+    "**/node_modules",
+    "**/*.js",
+    "**/*.mjs"
+  ],
+  "rules": {
+    "constructor-super": "error",
+    "for-direction": "error",
+    "getter-return": "error",
+    "no-async-promise-executor": "error",
+    "no-case-declarations": "error",
+    "no-class-assign": "error",
+    "no-compare-neg-zero": "error",
+    "no-cond-assign": "error",
+    "no-const-assign": "error",
+    "no-constant-binary-expression": "error",
+    "no-constant-condition": "error",
+    "no-control-regex": "error",
+    "no-debugger": "error",
+    "no-delete-var": "error",
+    "no-dupe-class-members": "error",
+    "no-dupe-else-if": "error",
+    "no-dupe-keys": "error",
+    "no-duplicate-case": "error",
+    "no-empty": "error",
+    "no-empty-character-class": "error",
+    "no-empty-pattern": "error",
+    "no-empty-static-block": "error",
+    "no-ex-assign": "error",
+    "no-extra-boolean-cast": "error",
+    "no-fallthrough": "error",
+    "no-func-assign": "error",
+    "no-global-assign": "error",
+    "no-import-assign": "error",
+    "no-invalid-regexp": "error",
+    "no-irregular-whitespace": "error",
+    "no-loss-of-precision": "error",
+    "no-misleading-character-class": "error",
+    "no-new-native-nonconstructor": "error",
+    "no-nonoctal-decimal-escape": "error",
+    "no-obj-calls": "error",
+    "no-prototype-builtins": "error",
+    "no-redeclare": "error",
+    "no-regex-spaces": "error",
+    "no-self-assign": "error",
+    "no-setter-return": "error",
+    "no-shadow-restricted-names": "error",
+    "no-sparse-arrays": "error",
+    "no-this-before-super": "error",
+    "no-unassigned-vars": "error",
+    "no-unexpected-multiline": "error",
+    "no-unreachable": "error",
+    "no-unsafe-finally": "error",
+    "no-unsafe-negation": "error",
+    "no-unsafe-optional-chaining": "error",
+    "no-unused-labels": "error",
+    "no-unused-private-class-members": "error",
+    "no-unused-vars": "error",
+    "no-useless-backreference": "error",
+    "no-useless-catch": "error",
+    "no-useless-escape": "error",
+    "no-with": "error",
+    "preserve-caught-error": "error",
+    "require-yield": "error",
+    "use-isnan": "error",
+    "valid-typeof": "error",
+    "no-array-constructor": "error",
+    "no-unused-expressions": "error",
+    "typescript/ban-ts-comment": "error",
+    "typescript/no-duplicate-enum-values": "error",
+    "typescript/no-empty-object-type": "error",
+    "typescript/no-explicit-any": "error",
+    "typescript/no-extra-non-null-assertion": "error",
+    "typescript/no-misused-new": "error",
+    "typescript/no-namespace": "error",
+    "typescript/no-non-null-asserted-optional-chain": "error",
+    "typescript/no-require-imports": "error",
+    "typescript/no-this-alias": "error",
+    "typescript/no-unnecessary-type-constraint": "error",
+    "typescript/no-unsafe-declaration-merging": "error",
+    "typescript/no-unsafe-function-type": "error",
+    "typescript/no-wrapper-object-types": "error",
+    "typescript/prefer-as-const": "error",
+    "typescript/prefer-namespace-keyword": "error",
+    "typescript/triple-slash-reference": "error"
+  },
+  "overrides": [
+    {
+      "files": [
+        "**/*.ts",
+        "**/*.tsx",
+        "**/*.mts",
+        "**/*.cts"
+      ],
+      "rules": {
+        "constructor-super": "off",
+        "getter-return": "off",
+        "no-class-assign": "off",
+        "no-const-assign": "off",
+        "no-dupe-class-members": "off",
+        "no-dupe-keys": "off",
+        "no-func-assign": "off",
+        "no-import-assign": "off",
+        "no-new-native-nonconstructor": "off",
+        "no-obj-calls": "off",
+        "no-redeclare": "off",
+        "no-setter-return": "off",
+        "no-this-before-super": "off",
+        "no-unreachable": "off",
+        "no-unsafe-negation": "off",
+        "no-var": "error",
+        "no-with": "off",
+        "prefer-const": "error",
+        "prefer-rest-params": "error",
+        "prefer-spread": "error"
+      }
+    },
+    {
+      "files": [
+        "**/*.ts"
+      ],
+      "jsPlugins": [
+        "@stylistic/eslint-plugin",
+        {
+          "name": "jsdoc-js",
+          "specifier": "eslint-plugin-jsdoc"
+        },
+        "oxlint-plugin-eslint"
+      ],
+      "rules": {
+        "@stylistic/comma-spacing": [
+          "warn",
+          {
+            "before": false,
+            "after": true
+          }
+        ],
+        "@stylistic/indent": [
+          "warn",
+          2
+        ],
+        "@stylistic/semi": [
+          "warn",
+          "always"
+        ],
+        "@stylistic/quotes": [
+          "warn",
+          "single",
+          {
+            "allowTemplateLiterals": "always"
+          }
+        ],
+        "@stylistic/member-delimiter-style": [
+          "warn",
+          {
+            "multiline": {
+              "delimiter": "semi",
+              "requireLast": true
+            },
+            "singleline": {
+              "delimiter": "comma",
+              "requireLast": false
+            }
+          }
+        ],
+        "@stylistic/type-annotation-spacing": "warn",
+        "@stylistic/space-unary-ops": "warn",
+        "@stylistic/keyword-spacing": "warn",
+        "@stylistic/max-len": [
+          "warn",
+          {
+            "code": 1000,
+            "comments": 100,
+            "ignoreTrailingComments": true,
+            "ignoreUrls": true,
+            "ignorePattern": "^ *((?<vt_comment>(//|\\*) @vt)|(?<table_comment>\\* \\| )|(?<commented_code>//  ))"
+          }
+        ],
+        "@stylistic/new-parens": "warn",
+        "@stylistic/no-extra-semi": "error",
+        "@stylistic/no-trailing-spaces": "warn",
+        "eslint-js/object-curly-spacing": [
+          "warn",
+          "always"
+        ],
+        "@stylistic/spaced-comment": [
+          "warn",
+          "always",
+          {
+            "markers": [
+              "/"
+            ],
+            "exceptions": [
+              "-"
+            ]
+          }
+        ],
+        "jsdoc-js/check-alignment": "warn",
+        "jsdoc-js/check-param-names": "warn",
+        "jsdoc-js/multiline-blocks": "warn",
+        "jsdoc-js/no-multi-asterisks": "warn",
+        "eslint-js/one-var": [
+          "warn",
+          "never"
+        ],
+        "eslint-js/no-restricted-syntax": [
+          "warn",
+          {
+            "selector": "CallExpression[callee.name='requestAnimationFrame']",
+            "message": "The global requestAnimationFrame() should be avoided, call it on the parent window from ICoreBrowserService."
+          },
+          {
+            "selector": "CallExpression[callee.name='cancelAnimationFrame']",
+            "message": "The global cancelAnimationFrame() should be avoided, call it on the parent window from ICoreBrowserService."
+          },
+          {
+            "selector": "CallExpression > MemberExpression[object.name='window'][property.name='requestAnimationFrame']",
+            "message": "window.requestAnimationFrame() should be avoided, call it on the parent window from ICoreBrowserService."
+          },
+          {
+            "selector": "CallExpression > MemberExpression[object.name='window'][property.name='cancelAnimationFrame']",
+            "message": "window.cancelAnimationFrame() should be avoided, call it on the parent window from ICoreBrowserService."
+          },
+          {
+            "selector": "MemberExpression[object.name='window'][property.name='devicePixelRatio']",
+            "message": "window.devicePixelRatio should be avoided, get it from ICoreBrowserService."
+          }
+        ],
+        "curly": [
+          "warn",
+          "multi-line"
+        ],
+        "eqeqeq": [
+          "warn",
+          "always"
+        ],
+        "no-duplicate-imports": "warn",
+        "no-else-return": [
+          "warn",
+          {
+            "allowElseIf": false
+          }
+        ],
+        "no-eval": "warn",
+        "no-irregular-whitespace": "warn",
+        "no-restricted-imports": [
+          "warn",
+          {
+            "patterns": [
+              ".*\\/out\\/.*"
+            ]
+          }
+        ],
+        "no-unsafe-finally": "warn",
+        "no-unused-vars": "off",
+        "no-var": "warn",
+        "no-empty": "off",
+        "no-empty-pattern": "off",
+        "no-cond-assign": "off",
+        "no-case-declarations": "off",
+        "for-direction": "off",
+        "no-prototype-builtins": "off",
+        "no-useless-escape": "off",
+        "no-self-assign": "off",
+        "no-async-promise-executor": "off",
+        "prefer-rest-params": "off",
+        "no-control-regex": "off",
+        "no-fallthrough": "off",
+        "prefer-spread": "off",
+        "prefer-const": "warn",
+        "no-unused-expressions": "off",
+        "typescript/array-type": [
+          "warn",
+          {
+            "default": "array",
+            "readonly": "generic"
+          }
+        ],
+        "typescript/consistent-type-assertions": "warn",
+        "typescript/consistent-type-definitions": "warn",
+        "typescript/explicit-function-return-type": [
+          "warn",
+          {
+            "allowExpressions": true
+          }
+        ],
+        "typescript/explicit-member-accessibility": [
+          "warn",
+          {
+            "accessibility": "explicit",
+            "overrides": {
+              "constructors": "off"
+            }
+          }
+        ],
+        "typescript/no-confusing-void-expression": [
+          "warn",
+          {
+            "ignoreArrowShorthand": true
+          }
+        ],
+        "typescript/no-useless-constructor": "warn",
+        "typescript/prefer-nullish-coalescing": [
+          "warn",
+          {
+            "ignorePrimitives": true
+          }
+        ],
+        "typescript/prefer-namespace-keyword": "warn",
+        "typescript/no-unused-vars": [
+          "warn",
+          {
+            "vars": "all",
+            "args": "none"
+          }
+        ],
+        "typescript/no-require-imports": "off",
+        "typescript/no-explicit-any": "off",
+        "typescript/no-wrapper-object-types": "off",
+        "typescript/no-empty-object-type": "off",
+        "typescript/no-unsafe-function-type": "off",
+        "typescript/no-this-alias": "off",
+        "typescript/no-namespace": "off",
+        "typescript/no-duplicate-enum-values": "off"
+      }
+    },
+    {
+      "files": [
+        "**/*.api.ts",
+        "**/*.test.ts"
+      ],
+      "rules": {
+        "eslint-js/object-curly-spacing": "off",
+        "@stylistic/max-len": "off",
+        "typescript/no-unused-vars": "off",
+        "typescript/explicit-function-return-type": "off",
+        "typescript/explicit-member-accessibility": "off"
+      }
+    },
+    {
+      "files": [
+        "demo/**/*.ts",
+        "**/*.benchmark.ts"
+      ],
+      "rules": {
+        "typescript/prefer-nullish-coalescing": "off"
+      }
+    }
+  ]
+}

.oxlintrc.typings.json

@@ -0,0 +1,120 @@
+{
+  "$schema": "./node_modules/oxlint/configuration_schema.json",
+  "options": {
+    "maxWarnings": 0
+  },
+  "env": {
+    "builtin": true
+  },
+  "overrides": [
+    {
+      "files": [
+        "typings/**/*.d.ts"
+      ],
+      "plugins": [
+        "typescript"
+      ],
+      "jsPlugins": [
+        "@stylistic/eslint-plugin",
+        {
+          "name": "jsdoc-js",
+          "specifier": "eslint-plugin-jsdoc"
+        },
+        "oxlint-plugin-eslint"
+      ],
+      "rules": {
+        "@stylistic/indent": [
+          "warn",
+          2
+        ],
+        "@stylistic/semi": [
+          "warn",
+          "always"
+        ],
+        "@stylistic/quotes": [
+          "warn",
+          "single",
+          {
+            "allowTemplateLiterals": "always"
+          }
+        ],
+        "@stylistic/member-delimiter-style": [
+          "warn",
+          {
+            "multiline": {
+              "delimiter": "semi",
+              "requireLast": true
+            },
+            "singleline": {
+              "delimiter": "comma",
+              "requireLast": false
+            }
+          }
+        ],
+        "@stylistic/type-annotation-spacing": "warn",
+        "@stylistic/keyword-spacing": "warn",
+        "@stylistic/max-len": [
+          "warn",
+          {
+            "code": 1000,
+            "comments": 80,
+            "ignoreUrls": true,
+            "ignorePattern": "^ *(?<ps_description>\\* Ps=)"
+          }
+        ],
+        "@stylistic/no-extra-semi": "error",
+        "@stylistic/no-trailing-spaces": "warn",
+        "eslint-js/object-curly-spacing": [
+          "warn",
+          "always"
+        ],
+        "@stylistic/spaced-comment": [
+          "warn",
+          "always",
+          {
+            "markers": [
+              "/"
+            ],
+            "exceptions": [
+              "-"
+            ]
+          }
+        ],
+        "@stylistic/comma-dangle": [
+          "warn",
+          {
+            "objects": "never",
+            "arrays": "never",
+            "functions": "never"
+          }
+        ],
+        "@stylistic/eol-last": "warn",
+        "curly": [
+          "warn",
+          "multi-line"
+        ],
+        "eqeqeq": [
+          "warn",
+          "always"
+        ],
+        "jsdoc-js/check-alignment": "warn",
+        "jsdoc-js/check-param-names": "warn",
+        "no-irregular-whitespace": "warn",
+        "typescript/array-type": [
+          "warn",
+          {
+            "default": "array",
+            "readonly": "generic"
+          }
+        ],
+        "typescript/explicit-function-return-type": [
+          "warn",
+          {
+            "allowExpressions": true
+          }
+        ],
+        "typescript/prefer-namespace-keyword": "warn"
+      }
+    }
+  ]
+}

.vscode/launch.json

@@ -15,9 +15,6 @@
         "--recursive",
         "${workspaceRoot}/out/**/*.test.js"
       ],
-      "env": {
-        "NODE_PATH": "${workspaceRoot}/out"
-      },
       "sourceMaps": true,
       "outFiles": [ "${workspaceRoot}/out/**/*.js" ],
       "internalConsoleOptions": "openOnSessionStart"

AGENTS.md

@@ -26,6 +26,7 @@ npm run build && npm run esbuild # Build all TypeScript and bundle
 - Integration tests: `npm run test-integration` (Playwright across Chrome/Firefox/WebKit)
 - Integration tests by file: `npm run test-integration -- test/playwright/InputHandler.test.ts`. Never use grep to filter tests, it doesn't work
 - Integration tests by addon: `npm run test-integration -- --suite=addon-search`. Suites always follow the format `addon-<something>`
+- Lint: `npm run lint` (oxlint with type-aware rules, then ESLint for `naming-convention` only), `npm run lint-api` for `typings/`, `npm run lint-fix` for oxlint auto-fix
 - Lint changes: `npm run lint-changes` to lint only changed files, `npm run lint-changes-fix` to fix them
 
 ## Addon Development Pattern
@@ -57,6 +58,13 @@ export class MyAddon implements ITerminalAddon {
 - Proposed APIs require `allowProposedApi: true` option
 - Constructor-only options (cols, rows) cannot be changed after instantiation
 
+**Disposable Management**:
+- When a disposable object can be replaced over time, prefer a registered `MutableDisposable` over manual dispose/reassign logic.
+- Register it on the owning class (for example, `this._register(new MutableDisposable())`) and assign through `.value`; this automatically disposes the previous value and avoids accidentally leaking resources.
+
+**TypeScript Constants**:
+- Prefer `const enum` over top-level `const` declarations for primitive constants when appropriate, since values are inlined and avoid runtime property lookups.
+
 **Testing Utilities**: Use `TestUtils.ts` helpers:
 - `openTerminal(ctx, options)` for setup
 - `pollFor(page, fn, expectedValue)` for async assertions
@@ -91,3 +99,15 @@ const cell = line?.getCell(0);
 ## Writing unit tests
 
 - Unit tests live alongside the source code file of the thing it's testing with a .test.ts suffix.
+
+## Cursor Cloud specific instructions
+
+**Demo server**: Start with `npm start` (port 3000). The demo server uses node-pty to spawn real shell sessions over WebSocket. Integration tests auto-start it via Playwright's `webServer` config, so you don't need to start it manually for `npm run test-integration`.
+
+**Build before testing**: Always run `npm run build && npm run esbuild` before `npm run test-unit`. Integration tests also need `npm run esbuild-demo-client` and `npm run esbuild-demo-server`. The update script handles this automatically on session start.
+
+**No external services**: This project has zero external dependencies (no databases, Docker, or APIs). Everything runs locally with Node.js.
+
+**TypeScript compiler**: The project uses `tsgo` (native TypeScript compiler preview) rather than standard `tsc`. It's installed via the `@typescript/native-preview` package.
+
+**Lint only changed files**: Prefer `npm run lint-changes` over `npm run lint` when iterating on code changes — it's significantly faster.

README.md

@@ -24,7 +24,36 @@ First, you need to install the module. We ship exclusively through [npm](https:/
 npm install --save @xterm/xterm
 ```
 
-To start using xterm.js on your browser, add the `xterm.js` and `xterm.css` to the head of your HTML page. Then create a `<div id="terminal"></div>` onto which xterm can attach itself. Finally, instantiate the `Terminal` object and then call the `open` function with the DOM object of the `div`.
+The recommended way to load xterm.js with the ES module syntax, either using TypeScript or a modern JS tooling. Note that both CommonJS and ES module files are shipped with the npm package.
+
+```javascript
+import { Terminal } from '@xterm/xterm';
+```
+
+Then instantiate a `Terminal` object, open it on an element and write to it:
+
+```javascript
+const term = new Terminal();
+term.open(document.getElementById('terminal'));
+term.write('Hello from \x1B[1;3;31mxterm.js\x1B[0m $ ')
+```
+
+Most use cases will hook up input and output to a pseudoterminal API such as [node-pty](https://www.npmjs.com/package/node-pty) which will drive the terminal.
+
+```javascript
+pty.onData(data => term.write(data));
+term.onData(data => pty.write(data));
+```
+
+Then make sure to also include the `css/xterm.css` file, for example in HTML:
+
+```html
+<link rel="stylesheet" href="node_modules/@xterm/xterm/css/xterm.css" />
+```
+
+### Standalone example
+
+Here is a complete standalone example in a HTML file:
 
 ```html
 <!doctype html>
@@ -36,7 +65,7 @@ To start using xterm.js on your browser, add the `xterm.js` and `xterm.css` to t
     <body>
       <div id="terminal"></div>
       <script>
-        var term = new Terminal();
+        const term = new Terminal();
         term.open(document.getElementById('terminal'));
         term.write('Hello from \x1B[1;3;31mxterm.js\x1B[0m $ ')
       </script>
@@ -44,14 +73,6 @@ To start using xterm.js on your browser, add the `xterm.js` and `xterm.css` to t
   </html>
 ```
 
-### Importing
-
-The recommended way to load xterm.js is via the ES6 module syntax:
-
-```javascript
-import { Terminal } from '@xterm/xterm';
-```
-
 ### Addons
 
 Addons are separate modules that extend the `Terminal` by building on the [xterm.js API](https://github.com/xtermjs/xterm.js/blob/master/typings/xterm.d.ts). To use an addon, you first need to install it in your project:
@@ -94,7 +115,7 @@ Since xterm.js is typically implemented as a developer tool, generally only mode
 
 ### Node.js Support
 
-We also publish [`xterm-headless`](https://www.npmjs.com/package/xterm-headless) which is a stripped down version of xterm.js that runs headless in Node.js. An example use case for this is to keep track of a terminal's state where the process is running and using the [serialize addon](https://www.npmjs.com/package/@xterm/addon-serialize) so it can get all state restored upon reconnection.
+We also publish [`@xterm/headless`](https://www.npmjs.com/package/@xterm/headless) which is a stripped down version of xterm.js that runs headless in Node.js. An example use case for this is to keep track of a terminal's state where the process is running and using the [serialize addon](https://www.npmjs.com/package/@xterm/addon-serialize) so it can get all state restored upon reconnection.
 
 ## API
 
@@ -229,6 +250,10 @@ Xterm.js is used in many world-class applications to provide great terminal expe
 - [**ecmaOS**](https://ecmaos.sh): A kernel and suite of applications tying modern web technologies into a browser-based operating system.
 - [**LabEx**](https://labex.io): Interactive learning platform with hands-on labs and xterm.js-based online terminals, focused on learn-by-doing approach.
 - [**EmuDevz**](https://afska.github.io/emudevz): A free coding game where players learn how to build an emulator from scratch.
+- [**SSH Connection Manager**](https://github.com/Amtrend/ssh-manager): Modern web-based SSH terminal and SFTP manager with AES-256 encryption, PWA support, and session management.
+- [**WooTTY**](https://github.com/icoretech/wootty): Flawless browser terminal for real operators.
+- [**Orca**](https://github.com/stablyai/orca): Agentic development environment for 100x builders.
+- [**4bit**](https://ciembor.github.io/4bit): Terminal Color Scheme Designer.
 - [And much more...](https://github.com/xtermjs/xterm.js/network/dependents?package_id=UGFja2FnZS0xNjYzMjc4OQ%3D%3D)
 
 Do you use xterm.js in your application as well? Please [open a Pull Request](https://github.com/sourcelair/xterm.js/pulls) to include it here. We would love to have it on our list. Please add any new contributions to the end of the list.

addons/addon-attach/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-attach/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-clipboard/package.json

@@ -16,13 +16,10 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",
     "start": "node ../../demo/start"
-  },
-  "dependencies": {
-    "js-base64": "^3.7.5"
   }
 }

addons/addon-clipboard/src/ClipboardAddon.ts

@@ -4,8 +4,7 @@
  */
 
 import type { IDisposable, ITerminalAddon, Terminal } from '@xterm/xterm';
-import { type IClipboardProvider, ClipboardSelectionType, type IBase64 } from '@xterm/addon-clipboard';
-import { Base64 as JSBase64 } from 'js-base64';
+import { type IClipboardProvider, type IBase64 } from '@xterm/addon-clipboard';
 
 export class ClipboardAddon implements ITerminalAddon {
   private _terminal?: Terminal;
@@ -25,7 +24,7 @@ export class ClipboardAddon implements ITerminalAddon {
     return this._disposable?.dispose();
   }
 
-  private _readText(sel: ClipboardSelectionType, data: string): void {
+  private _readText(sel: string, data: string): void {
     const b64 = this._base64.encodeText(data);
     this._terminal?.input(`\x1b]52;${sel};${b64}\x07`, false);
   }
@@ -36,7 +35,7 @@ export class ClipboardAddon implements ITerminalAddon {
       return true;
     }
 
-    const pc = args[0] as ClipboardSelectionType;
+    const pc = args[0];
     const pd = args[1];
     if (pd === '?') {
       const text = this._provider.readText(pc);
@@ -70,30 +69,23 @@ export class ClipboardAddon implements ITerminalAddon {
 }
 
 export class BrowserClipboardProvider implements IClipboardProvider {
-  public async readText(selection: ClipboardSelectionType): Promise<string> {
-    if (selection !== 'c') {
-      return Promise.resolve('');
-    }
+  public readText(selection: string): Promise<string> {
     return navigator.clipboard.readText();
   }
 
-  public async writeText(selection: ClipboardSelectionType, text: string): Promise<void> {
-    if (selection !== 'c') {
-      return Promise.resolve();
-    }
+  public writeText(selection: string, text: string): Promise<void> {
     return navigator.clipboard.writeText(text);
   }
 }
 
 export class Base64 implements IBase64 {
   public encodeText(data: string): string {
-    return JSBase64.encode(data);
+    return btoa(data);
   }
   public decodeText(data: string): string {
-    const text = JSBase64.decode(data);
-    if (!JSBase64.isValid(data) || JSBase64.encode(text) !== data) {
-      return '';
-    }
-    return text;
+    try {
+      return atob(data);
+    } catch {}
+    return '';
   }
 }

addons/addon-clipboard/test/ClipboardAddon.test.ts

@@ -20,7 +20,7 @@ test.describe('ClipboardAddon', () => {
 
   test.beforeEach(async ({}, testInfo) => {
     // DEBT: This test doesn't work since the migration to @playwright/test
-    if (ctx.browser.browserType().name() !== 'chromium') {
+    if (ctx.browser.browserType().name() === 'webkit') {
       testInfo.skip();
       return;
     }
@@ -48,6 +48,14 @@ test.describe('ClipboardAddon', () => {
       await ctx.proxy.write(`\x1b]52;c;${testDataEncoded}\x07`);
       deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), testDataDecoded);
     });
+    test('primary selection', async () => {
+      await ctx.proxy.write(`\x1b]52;p;${testDataEncoded}\x07`);
+      deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), testDataDecoded);
+    });
+    test('empty selection (default)', async () => {
+      await ctx.proxy.write(`\x1b]52;;${testDataEncoded}\x07`);
+      deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), testDataDecoded);
+    });
     test('invalid base64 string', async () => {
       await ctx.proxy.write(`\x1b]52;c;${testDataEncoded}invalid\x07`);
       deepEqual(await ctx.page.evaluate(() => window.navigator.clipboard.readText()), '');
@@ -60,15 +68,24 @@ test.describe('ClipboardAddon', () => {
   });
 
   test.describe('read data', async function (): Promise<any> {
-    test('simple string', async () => {
+    test.beforeAll(async () => {
       await ctx.page.evaluate(`
         window.data = [];
         window.term.onData(e => data.push(e));
       `);
+    });
+    test('simple string', async () => {
+      await ctx.page.evaluate('window.data.length = 0;');
       await ctx.page.evaluate(() => window.navigator.clipboard.writeText('hello world'));
       await ctx.proxy.write(`\x1b]52;c;?\x07`);
       deepEqual(await ctx.page.evaluate('window.data'), [`\x1b]52;c;${testDataEncoded}\x07`]);
     });
+    test('primary selection', async () => {
+      await ctx.page.evaluate('window.data.length = 0;');
+      await ctx.page.evaluate(() => window.navigator.clipboard.writeText('hello world'));
+      await ctx.proxy.write(`\x1b]52;p;?\x07`);
+      deepEqual(await ctx.page.evaluate('window.data'), [`\x1b]52;p;${testDataEncoded}\x07`]);
+    });
     test('clear clipboard', async () => {
       await ctx.proxy.write(`\x1b]52;c;!\x07`);
       await ctx.proxy.write(`\x1b]52;c;?\x07`);

addons/addon-clipboard/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-clipboard/typings/addon-clipboard.d.ts

@@ -30,18 +30,6 @@ declare module '@xterm/addon-clipboard' {
     public dispose(): void
   }
 
-  /**
-   * Clipboard selection type. This is used to specify which selection buffer to
-   * read or write to.
-   * - SYSTEM `c`: The system clipboard.
-   * - PRIMARY `p`: The primary clipboard. This is provided for compatibility
-   *  with Linux X11.
-   */
-  export const enum ClipboardSelectionType {
-    SYSTEM = 'c',
-    PRIMARY = 'p',
-  }
-
   export interface IBase64 {
     /**
     * Converts a utf-8 string to a base64 string.
@@ -78,36 +66,39 @@ declare module '@xterm/addon-clipboard' {
   export interface IClipboardProvider {
     /**
      * Gets the clipboard content.
-     * @param selection The clipboard selection to read.
+     * @param selection The clipboard selection to read (see OSC 52 spec of xterm).
      * @returns A promise that resolves with clipboard selection data.
      */
-    readText(selection: ClipboardSelectionType): string | Promise<string>;
+    readText(selection: string): string | Promise<string>;
 
     /**
      * Sets the clipboard content.
-     * @param selection The clipboard selection to set.
+     * @param selection The clipboard selection to set (see OSC 52 spec of xterm).
      * @param data The clipboard text to write.
      */
-    writeText(selection: ClipboardSelectionType, text: string): void | Promise<void>;
+    writeText(selection: string, text: string): void | Promise<void>;
   }
 
   /**
-   * The clipboard provider interface that enables xterm.js to access the system clipboard.
+   * The clipboard provider interface that enables xterm.js to access the browser clipboard.
+   *
+   * Note this this clipboard provider does not implement own cut buffers as xterm does,
+   * but redirect the selection parameter always to navigator.clipboard.
    */
   export class BrowserClipboardProvider implements IClipboardProvider{
     /**
      * Reads text from the clipboard.
-     * @param selection The selection type to read from.
+     * @param selection The selection type to read from (always refers to navigator.clipboard).
      * @returns A promise that resolves with the text from the clipboard.
      */
-    public readText(selection: ClipboardSelectionType): Promise<string>;
+    public readText(selection: string): Promise<string>;
 
     /**
      * Writes text to the clipboard.
-     * @param selection The selection type to write to.
+     * @param selection The selection type to write to (always refers to navigator.clipboard).
      * @param data The text to write to the clipboard.
      * @returns A promise that resolves when the text has been written to the clipboard.
      */
-    public writeText(selection: ClipboardSelectionType, data: string): Promise<void>;
+    public writeText(selection: string, data: string): Promise<void>;
   }
 }

addons/addon-fit/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-fit/src/FitAddon.ts

@@ -19,8 +19,10 @@ interface ITerminalDimensions {
   cols: number;
 }
 
-const MINIMUM_COLS = 2;
-const MINIMUM_ROWS = 1;
+const enum Constants {
+  MINIMUM_COLS = 2,
+  MINIMUM_ROWS = 1
+}
 
 function getWindow(e: Node): Window {
   if (e?.ownerDocument?.defaultView) {
@@ -48,10 +50,7 @@ export class FitAddon implements ITerminalAddon, IFitApi {
       return;
     }
 
-    // Force a full render
-    if (this._terminal.rows !== dims.rows || this._terminal.cols !== dims.cols) {
-      this._terminal.resize(dims.cols, dims.rows);
-    }
+    this._terminal.resize(dims.cols, dims.rows);
   }
 
   public proposeDimensions(): ITerminalDimensions | undefined {
@@ -89,8 +88,8 @@ export class FitAddon implements ITerminalAddon, IFitApi {
     const availableHeight = parentElementHeight - elementPaddingVer;
     const availableWidth = parentElementWidth - elementPaddingHor - scrollbarWidth;
     const geometry = {
-      cols: Math.max(MINIMUM_COLS, Math.floor(availableWidth / dims.css.cell.width)),
-      rows: Math.max(MINIMUM_ROWS, Math.floor(availableHeight / dims.css.cell.height))
+      cols: Math.max(Constants.MINIMUM_COLS, Math.floor(availableWidth / dims.css.cell.width)),
+      rows: Math.max(Constants.MINIMUM_ROWS, Math.floor(availableHeight / dims.css.cell.height))
     };
     return geometry;
   }

addons/addon-fit/test/FitAddon.test.ts

@@ -119,6 +119,17 @@ test.describe('FitAddon', () => {
       strictEqual(await ctx.proxy.cols, 2);
       strictEqual(await ctx.proxy.rows, 1);
     });
+
+    test('same dimensions', async function(): Promise<any> {
+      await setDimensions();
+      await ctx.page.evaluate(`window.fit.fit()`);
+      const cols: number = await ctx.proxy.cols;
+      const rows: number = await ctx.proxy.rows;
+      // Calling fit() again at the same container size should not throw
+      await ctx.page.evaluate(`window.fit.fit()`);
+      strictEqual(await ctx.proxy.cols, cols);
+      strictEqual(await ctx.proxy.rows, rows);
+    });
   });
 });
 

addons/addon-fit/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-image/README.md

@@ -1,6 +1,7 @@
 ## @xterm/addon-image
 
-Inline image output in xterm.js. Supports SIXEL and iTerm's inline image protocol (IIP).
+Inline image output in xterm.js. Supports SIXEL, iTerm's inline image protocol (IIP)
+and partially Kitty's terminal graphics prtocol (TGP).
 
 
 ![](fixture/example.png)
@@ -25,12 +26,14 @@ const customSettings: IImageAddonOptions = {
   pixelLimit: 16777216,       // max. pixel size of a single image
   sixelSupport: true,         // enable sixel support
   sixelScrolling: true,       // whether to scroll on image output
-  sixelPaletteLimit: 256,     // initial sixel palette size
-  sixelSizeLimit: 25000000,   // size limit of a single sixel sequence
+  sixelPaletteLimit: 4096,    // initial sixel palette size
+  sixelSizeLimit: 33554432,   // size limit of a single sixel sequence
   storageLimit: 128,          // FIFO storage limit in MB
   showPlaceholder: true,      // whether to show a placeholder for evicted images
   iipSupport: true,           // enable iTerm IIP support
-  iipSizeLimit: 20000000      // size limit of a single IIP sequence
+  iipSizeLimit: 33554432,     // size limit of a single IIP sequence
+  kittySupport: true,         // enable Kitty graphics support
+  kittySizeLimit: 33554432    // size limit of a single Kitty sequence
 }
 
 // initialization
@@ -41,9 +44,6 @@ terminal.loadAddon(imageAddon);
 
 ### General Notes
 
-- *IMPORTANT:* The worker approach as done in previous releases got removed.
-  The addon contructor no longer expects a worker path as first argument.
-
 - By default the addon will activate these `windowOptions` reports on the terminal:
   - getWinSizePixels (CSI 14 t)
   - getCellSizePixels (CSI 16 t)
@@ -71,7 +71,7 @@ terminal.loadAddon(imageAddon);
 
 - **Cursor Positioning**  
   If scrolling is set, the cursor will be placed at the first image column of the last image row (VT340 mode).
-  Other cursor positioning modes as used by xterm or mintty are not supported.
+  Other cursor positioning modes as used by xterm or mintty are not supported for sixel.
 
 - **SIXEL Palette Handling**  
   By default the addon limits the palette size to 256 registers (as demanded by the DEC specification).
@@ -98,17 +98,24 @@ terminal.loadAddon(imageAddon);
   Set by default, change it with `{iipSupport: true}`.
 
   The IIP implementation has the following features / restrictions (sequence will silently fail for unmet conditions):
-  - Supported formats: PNG, JPEG and GIF
+  - Supported formats: PNG, JPEG, GIF and QOI
   - No animation support.
   - Image type hinting is not supported (always deducted from data header).
   - File download is not supported.
   - Filename gets parsed but not used.
   - Strict base64 handling as of RFC4648 §4 (standard alphabet, optional padding, no separator bytes allowed).
-  - Payload size may not exceed CEIL(sizeParameter * 4 / 3).
   - Image scaling beyond terminal viewport size is allowed (e.g. `width=200%`).
   - Image pixel size is restricted by `pixelLimit` (pre- and post resizing).
-  - Size parameter is restricted by `iipSizeLimit`.
-  - Cursor positioning behaves the same as for sixel (see above).
+  - Playload size is restricted by `iipSizeLimit`.
+  - size parameter is not mandatory anymore.
+  - Cursor gets positioned at the next cell of the last image line.
+  - ReportCellSize sequence is supported.
+  - Hi-res display support is currently limited (image gets blurred).
+
+- **Kitty Graphics Support (TGP)**  
+  Set by default, change it with `{kittySupport: true}`.
+
+  Note that the kitty graphics support is still WIP.
 
 
 ### Storage and Drawing Settings
@@ -125,6 +132,7 @@ The addon exposes two properties to interact with the storage limits at runtime:
 By default the addon will show a placeholder pattern for evicted images that are still part
 of the terminal (e.g. in the scrollback). The pattern can be deactivated by toggling `showPlaceholder`.
 
+
 ### Image Data Retrieval
 
 The addon provides the following API endpoints to retrieve raw image data as canvas:
@@ -138,6 +146,7 @@ The addon provides the following API endpoints to retrieve raw image data as can
   The buffer position is the 0-based absolute index (including scrollback at top).
   Note that the canvas gets created and data copied over for every call, thus it is not suitable for performance critical actions.
 
+
 ### Memory Usage
 
 The addon does most image processing in Javascript and therefore can occupy a rather big amount of memory. To get an idea where the memory gets eaten, lets look at the data flow and processing steps:
@@ -178,8 +187,8 @@ _How can I adjust the memory usage?_
   A constructor setting, thus you would have to anticipate, whether (multiple) terminals in your page gonna do lots of concurrent decoding. Since this is normally not the case and the memory usage is only temporarily peaking, a rather high value should work even with multiple terminals in one page.
 - `storageLimit`  
   A constructor and a runtime setting. In conjunction with `storageUsage` you can do runtime checks and adjust the limit to your needs. If you have to lower the limit below the current usage, images will be removed in FIFO order and may turn into a placeholder in the terminal's scrollback (if `showPlaceholder` is set). When adjusting keep in mind to leave enough room for memory peaking for decoding.
-- `sixelSizeLimit`  
-  A constructor setting. This has only a small impact on peaking memory during decoding. It is meant to avoid processing of overly big or broken SIXEL sequences at an earlier phase, thus may stop the decoder from entering its memory intensive task for potentially invalid data.
+- `sixelSizeLimit | iipSizeLimit | kittySizeLimit`  
+  Constructor settings. This has only a small impact on peaking memory during decoding. It is meant to avoid processing of overly big or broken image sequences at an earlier phase, thus may stop the invoked decoders from entering memory intensive tasks for potentially invalid data.
 
 
 ### Terminal Interaction
@@ -209,23 +218,5 @@ _How can I adjust the memory usage?_
 
 ### Status
 
-- Sixel support and image handling in xterm.js is considered beta quality.
-- IIP support is in alpha stage. Please file a bug for any awkwardities.
-
-
-### Changelog
-
-- 0.5.0 integrate with xtermjs base repo (at v0.4.3)
-- 0.4.3 defer canvas creation
-- 0.4.2 fix image canvas resize
-- 0.4.1 compat release for xterm.js 5.2.0
-- 0.4.0 IIP support
-- 0.3.1 compat release for xterm.js 5.1.0
-- 0.3.0 important change: worker removed from addon
-- 0.2.0 compat release for xterm.js 5.0.0
-- 0.1.3 bugfix: avoid striping
-- 0.1.2 bugfix: reset clear flag
-- 0.1.1 bugfixes:
-  - clear sticky image tiles on render
-  - create folder from bootstrap.sh
-  - fix peer dependency in package.json
+- Sixel and IIP support and image handling in xterm.js is considered beta quality.
+- Kitty support is in alpha stage. Please file a bug for any awkwardities or missing features.

addons/addon-image/package.json

@@ -18,13 +18,13 @@
     "xterm.js"
   ],
   "scripts": {
-    "prepackage": "../../node_modules/.bin/tsc -p .",
+    "prepackage": "../../node_modules/.bin/tsgo -p .",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",
     "start": "node ../../demo/start"
   },
   "devDependencies": {
     "sixel": "^0.16.0",
-    "xterm-wasm-parts": "^0.1.0"
+    "xterm-wasm-parts": "^0.4.1"
   }
 }

addons/addon-image/src/IIPHandler.ts

@@ -4,16 +4,26 @@
  */
 import { IImageAddonOptions, IOscHandler, IResetHandler, ITerminalExt } from './Types';
 import { ImageRenderer } from './ImageRenderer';
-import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
+import { IIPImageStorage } from './IIPImageStorage';
+import { CELL_SIZE_DEFAULT } from './ImageStorage';
 import Base64Decoder from 'xterm-wasm-parts/lib/base64/Base64Decoder.wasm';
-import { HeaderParser, IHeaderFields, HeaderState } from './IIPHeaderParser';
+import QoiDecoder from 'xterm-wasm-parts/lib/qoi/QoiDecoder.wasm';
+import { HeaderParser, IHeaderFields, HeaderState, SequenceType } from './IIPHeaderParser';
 import { imageType, UNSUPPORTED_TYPE } from './IIPMetrics';
 
-// limit hold memory in base64 decoder
-const KEEP_DATA = 4194304;
+// Local const enum mirror - esbuild can't inline const enums from external packages
+const enum DecoderConst {
+  // Limit held memory in base64 decoder (encoded bytes).
+  KEEP_DATA = 4194304,
+  // Initial buffer allocation for the decoder.
+  INITIAL_DATA = 1048576,
+  // Local mirror of const enum (esbuild can't inline const enums from external packages)
+  OK = 0
+}
 
 // default IIP header values
 const DEFAULT_HEADER: IHeaderFields = {
+  type: SequenceType.INVALID,
   name: 'Unnamed file',
   size: 0,
   width: 'auto',
@@ -27,21 +37,32 @@ export class IIPHandler implements IOscHandler, IResetHandler {
   private _aborted = false;
   private _hp = new HeaderParser();
   private _header: IHeaderFields = DEFAULT_HEADER;
-  private _dec = new Base64Decoder(KEEP_DATA);
+  private _dec: Base64Decoder;
+  private _qoiDec: QoiDecoder;
   private _metrics = UNSUPPORTED_TYPE;
+  private _isMultipart = false;
+  private _abortMulti = false;
 
   constructor(
     private readonly _opts: IImageAddonOptions,
     private readonly _renderer: ImageRenderer,
-    private readonly _storage: ImageStorage,
+    private readonly _storage: IIPImageStorage,
     private readonly _coreTerminal: ITerminalExt
-  ) {}
+  ) {
+    const maxEncodedBytes = Math.ceil(this._opts.iipSizeLimit * 4 / 3);
+    const initialBytes = Math.min(DecoderConst.INITIAL_DATA, maxEncodedBytes);
+    this._dec = new Base64Decoder(DecoderConst.KEEP_DATA, maxEncodedBytes, initialBytes);
+    this._qoiDec = new QoiDecoder(DecoderConst.KEEP_DATA);
+  }
 
-  public reset(): void {}
+  public reset(): void {
+    this._hp.reset();
+    this._dec.release();
+    this._qoiDec.release();
+  }
 
   public start(): void {
     this._aborted = false;
-    this._header = DEFAULT_HEADER;
     this._metrics  = UNSUPPORTED_TYPE;
     this._hp.reset();
   }
@@ -50,7 +71,7 @@ export class IIPHandler implements IOscHandler, IResetHandler {
     if (this._aborted) return;
 
     if (this._hp.state === HeaderState.END) {
-      if (this._dec.put(data, start, end)) {
+      if ((this._dec.put(data.subarray(start, end)) as number) !== DecoderConst.OK) {
         this._dec.release();
         this._aborted = true;
       }
@@ -61,15 +82,27 @@ export class IIPHandler implements IOscHandler, IResetHandler {
         return;
       }
       if (dataPos > 0) {
-        this._header = Object.assign({}, DEFAULT_HEADER, this._hp.fields);
-        if (!this._header.inline || !this._header.size || this._header.size > this._opts.iipSizeLimit) {
+        const seqType = this._hp.fields.type;
+        if (seqType === SequenceType.FILE) {
+          if (this._isMultipart) {
+            this._isMultipart = false;
+            this._abortMulti = false;
+            this._dec.release();
+          }
+          this._header = Object.assign({}, DEFAULT_HEADER, this._hp.fields);
+          if (!this._header.inline) {
+            this._aborted = true;
+            return;
+          }
+          this._dec.init();
+        } else if (this._abortMulti) {
           this._aborted = true;
           return;
         }
-        this._dec.init(this._header.size);
-        if (this._dec.put(data, dataPos, end)) {
+        if ((this._dec.put(data.subarray(dataPos, end)) as number) !== DecoderConst.OK) {
           this._dec.release();
           this._aborted = true;
+          if (this._isMultipart) this._abortMulti = true;
         }
       }
     }
@@ -78,11 +111,49 @@ export class IIPHandler implements IOscHandler, IResetHandler {
   public end(success: boolean): boolean | Promise<boolean> {
     if (this._aborted) return true;
 
+    if (this._hp.state !== HeaderState.END) {
+      if (this._hp.end()) return true;
+    }
+    const seqType = this._hp.fields.type;
+
+    if (seqType === SequenceType.FILEPART) return true;
+
+    if (seqType === SequenceType.REPORTCELLSIZE) {
+      // OSC 1337 ; ReportCellSize=[height];[width];[scale] ST
+      let width = CELL_SIZE_DEFAULT.width;
+      let height = CELL_SIZE_DEFAULT.height;
+      if (this._renderer.dimensions) {
+        width = this._renderer.dimensions.css.canvas.width / this._coreTerminal.cols;
+        height = this._renderer.dimensions.css.canvas.height / this._coreTerminal.rows;
+      }
+      const scale = this._coreTerminal._core._coreBrowserService?.dpr ?? 1;
+      const report = `\x1b]1337;ReportCellSize=${height.toFixed(3)};${width.toFixed(3)};${scale.toFixed(3)}\x1b\\`;
+      this._coreTerminal.input(report, false);
+      return true;
+    }
+
+    if (seqType === SequenceType.MULTIPARTFILE) {
+      this._header = Object.assign({}, DEFAULT_HEADER, this._hp.fields);
+      this._isMultipart = true;
+      this._abortMulti = false;
+      this._dec.release();
+      this._dec.init();
+      return true;
+    }
+
+    if (seqType === SequenceType.FILEEND) {
+      if (!this._isMultipart) return true;
+      this._isMultipart = false;
+      if (this._abortMulti || this._header.type !== SequenceType.MULTIPARTFILE) return true;
+    }
+
+    // fallthrough for SequenceType.FILE & SequenceType.FILEEND
+
     let w = 0;
     let h = 0;
 
     // early exit condition chain
-    let cond: number | boolean = true;
+    let cond: number | boolean;
     if (cond = success) {
       if (cond = !this._dec.end()) {
         this._metrics = imageType(this._dec.data8);
@@ -101,27 +172,27 @@ export class IIPHandler implements IOscHandler, IResetHandler {
       return true;
     }
 
-    // HACK: The types on Blob are too restrictive, this is a Uint8Array so the browser accepts it
-    const blob = new Blob([this._dec.data8 as Uint8Array<ArrayBuffer>], { type: this._metrics.mime });
-    this._dec.release();
-
-    if (!window.createImageBitmap) {
-      const url = URL.createObjectURL(blob);
-      const img = new Image();
-      return new Promise<boolean>(r => {
-        img.addEventListener('load', () => {
-          URL.revokeObjectURL(url);
-          const canvas = ImageRenderer.createCanvas(window.document, w, h);
-          canvas.getContext('2d')?.drawImage(img, 0, 0, w, h);
-          this._storage.addImage(canvas);
-          r(true);
-        });
-        img.src = url;
-        // sanity measure to avoid terminal blocking from dangling promise
-        // happens from corrupt data (onload never gets fired)
-        setTimeout(() => r(true), 1000);
-      });
+    let blob: Blob | ImageData;
+    if (this._metrics.mime === 'image/qoi') {
+      const data = this._qoiDec.decode(this._dec.data8);
+      blob = new ImageData(
+        new Uint8ClampedArray(data.buffer, data.byteOffset, data.byteLength),
+        this._qoiDec.width,
+        this._qoiDec.height
+      );
+      this._qoiDec.release();
+      if (w === this._qoiDec.width && h === this._qoiDec.height) {
+        // use fast-path if we don't need to rescale
+        this._dec.release();
+        const canvas = ImageRenderer.createCanvas(undefined, this._qoiDec.width, this._qoiDec.height);
+        canvas.getContext('2d')?.putImageData(blob, 0, 0);
+        this._storage.addImage(canvas);
+        return true;
+      }
+    } else {
+      blob = new Blob([this._dec.data8], { type: this._metrics.mime });
     }
+    this._dec.release();
     return createImageBitmap(blob, { resizeWidth: w, resizeHeight: h })
       .then(bm => {
         this._storage.addImage(bm);

addons/addon-image/src/IIPHeaderParser.test.ts

@@ -4,19 +4,20 @@
  */
 
 import { assert } from 'chai';
-import { HeaderParser, HeaderState, IHeaderFields } from './IIPHeaderParser';
+import { HeaderParser, HeaderState, IHeaderFields, SequenceType } from './IIPHeaderParser';
 
 
 const CASES: [string, IHeaderFields][] = [
-  ['File=size=123456;name=dGVzdA==:', {name: 'test', size: 123456}],
-  ['File=size=123456;name=dGVzdA:', {name: 'test', size: 123456}],
+  ['File=size=123456;name=dGVzdA==:', {type: SequenceType.FILE, name: 'test', size: 123456}],
+  ['File=size=123456;name=dGVzdA:', {type: SequenceType.FILE, name: 'test', size: 123456}],
   // utf-8 encoding in name
-  ['File=size=123456;name=w7xtbMOkdXTDnw==:', {name: 'ümläutß', size: 123456}],
-  ['File=size=123456;name=w7xtbMOkdXTDnw:', {name: 'ümläutß', size: 123456}],
+  ['File=size=123456;name=w7xtbMOkdXTDnw==:', {type: SequenceType.FILE, name: 'ümläutß', size: 123456}],
+  ['File=size=123456;name=w7xtbMOkdXTDnw:', {type: SequenceType.FILE, name: 'ümläutß', size: 123456}],
   // full header spec
   [
     'File=inline=1;width=10px;height=20%;preserveAspectRatio=1;size=123456;name=w7xtbMOkdXTDnw:',
     {
+      type: SequenceType.FILE,
       inline: 1,
       width: '10px',
       height: '20%',
@@ -28,6 +29,7 @@ const CASES: [string, IHeaderFields][] = [
   [
     'File=inline=1;width=auto;height=20;preserveAspectRatio=1;size=123456;name=w7xtbMOkdXTDnw:',
     {
+      type: SequenceType.FILE,
       inline: 1,
       width: 'auto',
       height: '20',
@@ -101,7 +103,7 @@ describe('IIPHeaderParser', () => {
     let res = hp.parse(inp, 0, inp.length);
     assert.strictEqual(res, inp.length);
     assert.strictEqual(hp.state, HeaderState.END);
-    assert.deepEqual(hp.fields, {name: 'test', size: 0});
+    assert.deepEqual(hp.fields, {type: SequenceType.FILE, name: 'test', size: 0});
     hp.reset();
     inp = fromBs(CASES[0][0]);
     res = hp.parse(inp, 0, inp.length);
@@ -115,7 +117,7 @@ describe('IIPHeaderParser', () => {
     let res = hp.parse(inp, 0, inp.length);
     assert.strictEqual(res, inp.length);
     assert.strictEqual(hp.state, HeaderState.END);
-    assert.deepEqual(hp.fields, {name: '', size: 123456});
+    assert.deepEqual(hp.fields, {type: SequenceType.FILE, name: '', size: 123456});
     hp.reset();
     inp = fromBs(CASES[0][0]);
     res = hp.parse(inp, 0, inp.length);
@@ -135,4 +137,124 @@ describe('IIPHeaderParser', () => {
     assert.strictEqual(hp.state, HeaderState.END);
     assert.deepEqual(hp.fields, CASES[0][1]);
   });
+  it('FilePart sequence', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('FilePart=w7xtbMOkdXTDnw');
+    const res = hp.parse(inp, 0, inp.length);
+    assert.strictEqual(res, 9);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields.type, SequenceType.FILEPART);
+  });
+  it('FilePart sequence - bytewise', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('FilePart=w7xtbMOkdXTDnw');
+    let res = -2;
+    let pos = 0;
+    while (res === -2 && pos < inp.length) {
+      res = hp.parse(new Uint32Array([inp[pos++]]), 0, 1);
+    }
+    assert.strictEqual(res, 1);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields.type, SequenceType.FILEPART);
+  });
+  it('MultipartFile sequence', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('MultipartFile=inline=1;width=10px;height=20%;preserveAspectRatio=1;size=123456;name=w7xtbMOkdXTDnw');
+    let res = hp.parse(inp, 0, inp.length);
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.VALUE);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(
+      hp.fields,
+      {
+        type: SequenceType.MULTIPARTFILE,
+        inline: 1,
+        width: '10px',
+        height: '20%',
+        preserveAspectRatio: 1,
+        size: 123456,
+        name: 'ümläutß'
+      }
+    );
+  });
+  it('MultipartFile sequence - bytewise', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('MultipartFile=inline=1;width=10px;height=20%;preserveAspectRatio=1;size=123456;name=w7xtbMOkdXTDnw');
+    let res = -2;
+    let pos = 0;
+    while (res === -2 && pos < inp.length) {
+      res = hp.parse(new Uint32Array([inp[pos++]]), 0, 1);
+    }
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.VALUE);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(
+      hp.fields,
+      {
+        type: SequenceType.MULTIPARTFILE,
+        inline: 1,
+        width: '10px',
+        height: '20%',
+        preserveAspectRatio: 1,
+        size: 123456,
+        name: 'ümläutß'
+      }
+    );
+  });
+  it('FileEnd sequence', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('FileEnd');
+    let res = hp.parse(inp, 0, inp.length);
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.START);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields.type, SequenceType.FILEEND);
+  });
+  it('FileEnd sequence - bytewise', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('FileEnd');
+    let res = -2;
+    let pos = 0;
+    while (res === -2 && pos < inp.length) {
+      res = hp.parse(new Uint32Array([inp[pos++]]), 0, 1);
+    }
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.START);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields.type, SequenceType.FILEEND);
+  });
+  it('ReportCellSize sequence', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('ReportCellSize');
+    let res = hp.parse(inp, 0, inp.length);
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.START);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields, { type: SequenceType.REPORTCELLSIZE });
+  });
+  it('ReportCellSize sequence - bytewise', () => {
+    const hp = new HeaderParser();
+    const inp = fromBs('ReportCellSize');
+    let res = -2;
+    let pos = 0;
+    while (res === -2 && pos < inp.length) {
+      res = hp.parse(new Uint32Array([inp[pos++]]), 0, 1);
+    }
+    assert.strictEqual(res, -2);
+    assert.strictEqual(hp.state, HeaderState.START);
+    res = hp.end();
+    assert.strictEqual(res, 0);
+    assert.strictEqual(hp.state, HeaderState.END);
+    assert.deepEqual(hp.fields, { type: SequenceType.REPORTCELLSIZE });
+  });
 });

addons/addon-image/src/IIPHeaderParser.ts

@@ -6,9 +6,27 @@
 // eslint-disable-next-line
 declare const Buffer: any;
 
+export const enum HeaderState {
+  START = 0,
+  ABORT = 1,
+  KEY = 2,
+  VALUE = 3,
+  END = 4
+}
+
+export const enum SequenceType {
+  INVALID = 0,
+  FILE = 1,
+  MULTIPARTFILE = 2,
+  FILEPART = 3,
+  FILEEND = 4,
+  REPORTCELLSIZE = 5
+}
 
 export interface IHeaderFields {
   [key: string]: number | string | Uint32Array | null | undefined;
+  // sequence type
+  type: SequenceType;
   // base-64 encoded filename. Defaults to "Unnamed file".
   name: string;
   // File size in bytes. The file transfer will be canceled if this size is exceeded.
@@ -29,14 +47,6 @@ export interface IHeaderFields {
   inline?: number;
 }
 
-export const enum HeaderState {
-  START = 0,
-  ABORT = 1,
-  KEY = 2,
-  VALUE = 3,
-  END = 4
-}
-
 // field value decoders
 
 // ASCII bytes to string
@@ -92,7 +102,19 @@ const DECODERS: {[key: string]: (v: Uint32Array) => number | string} = {
 };
 
 
+// sequence type markers
+// File
 const FILE_MARKER = [70, 105, 108, 101];
+// MultipartFile
+const MULTIPARTFILE_MARKER = [77, 117, 108, 116, 105, 112, 97, 114, 116, 70, 105, 108, 101];
+// FilePart
+const FILEPART_MARKER = [70, 105, 108, 101, 80, 97, 114, 116];
+// FileEnd
+const FILEEND_MARKER = [70, 105, 108, 101, 69, 110, 100];
+// ReportCellSize
+const REPORTCELLSIZE_MARKER = [82, 101, 112, 111, 114, 116, 67, 101, 108, 108, 83, 105, 122, 101];
+
+// max allowed chars for sequence header
 const MAX_FIELDCHARS = 1024;
 
 
@@ -111,12 +133,43 @@ export class HeaderParser {
     this._key = '';
   }
 
+  public end(): number {
+    if (this.state === HeaderState.START) {
+      if (this._position === FILEEND_MARKER.length) {
+        for (let k = 0; k < FILEEND_MARKER.length; ++k) {
+          if (this._buffer[k] !== FILEEND_MARKER[k]) return this._a();
+        }
+        this.fields['type'] = SequenceType.FILEEND;
+        this.state = HeaderState.END;
+        return 0;
+      }
+      if (this._position === REPORTCELLSIZE_MARKER.length) {
+        for (let k = 0; k < REPORTCELLSIZE_MARKER.length; ++k) {
+          if (this._buffer[k] !== REPORTCELLSIZE_MARKER[k]) return this._a();
+        }
+        this.fields['type'] = SequenceType.REPORTCELLSIZE;
+        this.state = HeaderState.END;
+        return 0;
+      }
+      return this._a();
+    }
+    if (this.state === HeaderState.END) return 0;
+    if (this.state === HeaderState.VALUE
+      && this.fields.type === SequenceType.MULTIPARTFILE
+    ) {
+      if (!this._storeValue(this._position)) return this._a();
+      this.state = HeaderState.END;
+      return 0;
+    }
+    return this._a();
+  }
+
   public parse(data: Uint32Array, start: number, end: number): number {
     let state = this.state;
     let pos = this._position;
     const buffer = this._buffer;
     if (state === HeaderState.ABORT || state === HeaderState.END) return -1;
-    if (state === HeaderState.START && pos > 6) return -1;
+    if (state === HeaderState.START && pos > 14) return -1;
     for (let i = start; i < end; ++i) {
       const c = data[i];
       switch (c) {
@@ -127,8 +180,29 @@ export class HeaderParser {
           break;
         case 61: // =
           if (state === HeaderState.START) {
-            for (let k = 0; k < FILE_MARKER.length; ++k) {
-              if (buffer[k] !== FILE_MARKER[k]) return this._a();
+            if (buffer[0] === 70) {
+              // 'File' or 'FilePart'
+              let k = 0;
+              for (; k < FILE_MARKER.length; ++k) {
+                if (buffer[k] !== FILE_MARKER[k]) return this._a();
+              }
+              this.fields['type'] = SequenceType.FILE;
+              if (pos === FILEPART_MARKER.length) {
+                for (; k < FILEPART_MARKER.length; ++k) {
+                  if (buffer[k] !== FILEPART_MARKER[k]) return this._a();
+                }
+                this.fields['type'] = SequenceType.FILEPART;
+                this.state = HeaderState.END;
+                return i + 1;
+              }
+            } else if (buffer[0] === 77) {
+              // 'MultipartFile'
+              for (let k = 0; k < MULTIPARTFILE_MARKER.length; ++k) {
+                if (buffer[k] !== MULTIPARTFILE_MARKER[k]) return this._a();
+              }
+              this.fields['type'] = SequenceType.MULTIPARTFILE;
+            } else {
+              return this._a();
             }
             state = HeaderState.KEY;
             pos = 0;
@@ -158,6 +232,7 @@ export class HeaderParser {
   }
 
   private _a(): number {
+    this.fields.type = SequenceType.INVALID;
     this.state = HeaderState.ABORT;
     return -1;
   }

addons/addon-image/src/IIPImageStorage.ts

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2023 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IAddImageOpts } from './Types';
+import { ImageStorage } from './ImageStorage';
+
+/**
+ * IIP (iTerm Image Protocol) specific image storage controller.
+ *
+ * Wraps the shared ImageStorage with IIP protocol semantics:
+ * - Always uses scrolling mode (cursor advances with image)
+ */
+export class IIPImageStorage {
+  private _addImageOpts: IAddImageOpts = { scrolling: true, layer: 'top', zIndex: 0, cursorPos: 'iip' };
+  constructor(
+    private readonly _storage: ImageStorage
+  ) {}
+
+  /**
+   * Add an IIP image to storage.
+   * Always uses scrolling mode — cursor advances past the image.
+   */
+  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+    this._storage.addImage(img, this._addImageOpts);
+  }
+}

addons/addon-image/src/IIPMetrics.test.ts

@@ -30,7 +30,8 @@ const TEST_IMAGES: [string, IMetrics][] = [
   ['iphone_hdr_YES.jpg', { mime: 'image/jpeg', width: 3264, height: 2448 }],
   ['nikon-e950.jpg', { mime: 'image/jpeg', width: 800, height: 600 }],
   ['agfa-makernotes.jpg', { mime: 'image/jpeg', width: 8, height: 8 }],
-  ['sony-alpha-6000.jpg', { mime: 'image/jpeg', width: 6000, height: 4000 }]
+  ['sony-alpha-6000.jpg', { mime: 'image/jpeg', width: 6000, height: 4000 }],
+  ['dice.qoi', { mime: 'image/qoi', width: 800, height: 600 }],
 ];
 
 

addons/addon-image/src/IIPMetrics.ts

@@ -4,7 +4,7 @@
  */
 
 
-export type ImageType = 'image/png' | 'image/jpeg' | 'image/gif' | 'unsupported' | '';
+export type ImageType = 'image/png' | 'image/jpeg' | 'image/gif' | 'image/qoi' | 'unsupported' | '';
 
 export interface IMetrics {
   mime: ImageType;
@@ -45,6 +45,14 @@ export function imageType(d: Uint8Array): IMetrics {
       height: d[9] << 8 | d[8]
     };
   }
+  // QOI: qoif
+  if (d32[0] === 0x66696F71) {
+    return {
+      mime: 'image/qoi',
+      width: d[4] << 24 | d[5] << 16 | d[6] << 8 | d[7],
+      height: d[8] << 24 | d[9] << 16 | d[10] << 8 | d[11]
+    };
+  }
   return UNSUPPORTED_TYPE;
 }
 

addons/addon-image/src/ImageAddon.ts

@@ -5,24 +5,72 @@
 
 import type { ITerminalAddon, IDisposable } from '@xterm/xterm';
 import type { ImageAddon as IImageApi } from '@xterm/addon-image';
+import { Emitter, type IEvent } from 'common/Event';
 import { IIPHandler } from './IIPHandler';
 import { ImageRenderer } from './ImageRenderer';
 import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
+import { KittyGraphicsHandler } from './kitty/KittyGraphicsHandler';
+import { KittyImageStorage } from './kitty/KittyImageStorage';
 import { SixelHandler } from './SixelHandler';
+import { SixelImageStorage } from './SixelImageStorage';
+import { IIPImageStorage } from './IIPImageStorage';
 import { ITerminalExt, IImageAddonOptions, IResetHandler } from './Types';
 
+
+/**
+ * Document VT features provided by this addon.
+ *
+ * @vt: #E[Supported via @xterm/addon-image.] DCS SIXEL "SIXEL Graphics"  "DCS Ps ; Ps ; Ps ; q Pt ST"  "Draw SIXEL image."
+ *
+ * Sixel support is provided by the addon @xterm/addon-image with these limitations:
+ * - immediate coloring (no shared palette, allows high color settings of `img2sixel`)
+ * - max. palette size of 4096 colors
+ * - max. pixel width of 16K
+ * - max. 25 MB per sixel sequence
+ * - VT340 cursor positioning (begin of last sixel data row)
+ *
+ * See [addon readme](https://github.com/xtermjs/xterm.js/tree/master/addons/addon-image) for more details.
+ *
+ *
+ * @vt: #E[Supported via @xterm/addon-image.] OSC 1337  "iTerm2 Commands"   "OSC 1337 ; Pt BEL"  "Custom iTerm2 commands."
+ *
+ * Only the inline image protocol (IIP) is supported by the addon @xterm/addon-image with
+ * the following limitations:
+ * - sequence:
+ *   - format: `OSC 1337 ; File=inline=1 ; size=<unencoded size> ; ... : <base64 payload> BEL`
+ *   - size param must be set and payload may not exceed CEIL(size * 4 / 3)
+ *   - strict base64 handling as of RFC4648 §4 (standard alphabet, optional padding,
+ *     no separator bytes allowed)
+ *   - supported params: size, name, width, height, preserveAspectRatio
+ * - image formats: PNG, JPEG and GIF
+ * - no animation support (renders first image of a GIF)
+ * - no multipart support
+ * - VT340 cursor positioning (begin of last sixel data row)
+ *
+ * See [addon readme](https://github.com/xtermjs/xterm.js/tree/master/addons/addon-image)
+ * and [iTerm2 IIP docs](https://iterm2.com/documentation-images.html) for more details.
+ *
+ *
+ * @vt: #E[Supported via @xterm/addon-image.] APC KITTY_GRAPHICS "Kitty Graphics"  "APC G Pt ST"  "Kitty Graphics Protocol."
+ *
+ * Kitty graphics support is provided by the addon @xterm/addon-image.
+ * Note that while basic image output already works, this is still work in progress.
+ */
+
 // default values of addon ctor options
 const DEFAULT_OPTIONS: IImageAddonOptions = {
   enableSizeReports: true,
   pixelLimit: 16777216, // limit to 4096 * 4096 pixels
   sixelSupport: true,
   sixelScrolling: true,
-  sixelPaletteLimit: 256,
-  sixelSizeLimit: 25000000,
+  sixelPaletteLimit: 4096,
+  sixelSizeLimit: 33554432,
   storageLimit: 128,
   showPlaceholder: true,
   iipSupport: true,
-  iipSizeLimit: 20000000
+  iipSizeLimit: 33554432,
+  kittySupport: true,
+  kittySizeLimit: 33554432
 };
 
 // max palette size supported by the sixel lib (compile time setting)
@@ -56,6 +104,8 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
   private _disposables: IDisposable[] = [];
   private _terminal: ITerminalExt | undefined;
   private _handlers: Map<String, IResetHandler> = new Map();
+  private readonly _onImageAdded = new Emitter<void>();
+  public readonly onImageAdded: IEvent<void> = this._onImageAdded.event;
 
   constructor(opts?: Partial<IImageAddonOptions>) {
     this._opts = Object.assign({}, DEFAULT_OPTIONS, opts);
@@ -68,6 +118,7 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
     }
     this._disposables.length = 0;
     this._handlers.clear();
+    this._onImageAdded.dispose();
   }
 
   private _disposeLater(...args: IDisposable[]): void {
@@ -82,14 +133,10 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
     // internal data structures
     this._renderer = new ImageRenderer(terminal);
     this._storage = new ImageStorage(terminal, this._renderer, this._opts);
+    this._storage.onImageAdded = () => this._onImageAdded.fire();
 
     // enable size reports
     if (this._opts.enableSizeReports) {
-      // const windowOptions = terminal.getOption('windowOptions');
-      // windowOptions.getWinSizePixels = true;
-      // windowOptions.getCellSizePixels = true;
-      // windowOptions.getWinSizeChars = true;
-      // terminal.setOption('windowOptions', windowOptions);
       const windowOps = terminal.options.windowOptions ?? {};
       windowOps.getWinSizePixels = true;
       windowOps.getCellSizePixels = true;
@@ -129,7 +176,8 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
 
     // SIXEL handler
     if (this._opts.sixelSupport) {
-      const sixelHandler = new SixelHandler(this._opts, this._storage!, terminal);
+      const sixelStorage = new SixelImageStorage(this._storage!, this._opts, this._renderer!, terminal);
+      const sixelHandler = new SixelHandler(this._opts, sixelStorage, terminal);
       this._handlers.set('sixel', sixelHandler);
       this._disposeLater(
         terminal._core._inputHandler._parser.registerDcsHandler({ final: 'q' }, sixelHandler)
@@ -138,12 +186,25 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
 
     // iTerm IIP handler
     if (this._opts.iipSupport) {
-      const iipHandler = new IIPHandler(this._opts, this._renderer!, this._storage!, terminal);
+      const iipStorage = new IIPImageStorage(this._storage!);
+      const iipHandler = new IIPHandler(this._opts, this._renderer!, iipStorage, terminal);
       this._handlers.set('iip', iipHandler);
       this._disposeLater(
         terminal._core._inputHandler._parser.registerOscHandler(1337, iipHandler)
       );
     }
+
+    // Kitty graphics handler
+    if (this._opts.kittySupport) {
+      const kittyStorage = new KittyImageStorage(this._storage!);
+      const kittyHandler = new KittyGraphicsHandler(this._opts, this._renderer!, kittyStorage, terminal);
+      this._handlers.set('kitty', kittyHandler);
+      this._disposeLater(
+        kittyStorage,
+        kittyHandler,
+        terminal._core._inputHandler._parser.registerApcHandler({ final: 'G' }, kittyHandler)
+      );
+    }
   }
 
   // Note: storageLimit is skipped here to not intoduce a surprising side effect.
@@ -194,7 +255,7 @@ export class ImageAddon implements ITerminalAddon, IImageApi {
   }
 
   private _report(s: string): void {
-    this._terminal?._core.coreService.triggerDataEvent(s);
+    this._terminal?._core.input(s, false);
   }
 
   private _decset(params: (number | number[])[]): boolean {

addons/addon-image/src/ImageRenderer.ts

@@ -5,11 +5,13 @@
 
 import { toRGBA8888 } from 'sixel/lib/Colors';
 import { IDisposable } from '@xterm/xterm';
-import { ICellSize, ITerminalExt, IImageSpec, IRenderDimensions, IRenderService } from './Types';
+import { ICellSize, ImageLayer, ITerminalExt, IImageSpec, IRenderDimensions, IRenderService } from './Types';
 import { Disposable, MutableDisposable, toDisposable } from 'common/Lifecycle';
 
-const PLACEHOLDER_LENGTH = 4096;
-const PLACEHOLDER_HEIGHT = 24;
+const enum Constants {
+  PLACEHOLDER_LENGTH = 4096,
+  PLACEHOLDER_HEIGHT = 24
+}
 
 /**
  * ImageRenderer - terminal frontend extension:
@@ -18,8 +20,9 @@ const PLACEHOLDER_HEIGHT = 24;
  * - draw image tiles onRender
  */
 export class ImageRenderer extends Disposable implements IDisposable {
-  public canvas: HTMLCanvasElement | undefined;
-  private _ctx: CanvasRenderingContext2D | null | undefined;
+  /** @deprecated Kept for backward compat — points to top layer canvas. */
+  public get canvas(): HTMLCanvasElement | undefined { return this._layers.get('top')?.canvas; }
+  private _layers = new Map<ImageLayer, CanvasRenderingContext2D>();
   private _placeholder: HTMLCanvasElement | undefined;
   private _placeholderBitmap: ImageBitmap | undefined;
   private _optionsRefresh = this._register(new MutableDisposable());
@@ -86,6 +89,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
     });
     this._register(toDisposable(() => {
       this.removeLayerFromDom();
+      this.removeLayerFromDom('bottom');
       if (this._terminal._core && this._oldOpen) {
         this._terminal._core.open = this._oldOpen;
         this._oldOpen = undefined;
@@ -95,8 +99,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
         this._oldSetRenderer = undefined;
       }
       this._renderService = undefined;
-      this.canvas = undefined;
-      this._ctx = undefined;
+      this._layers.clear();
       this._placeholderBitmap?.close();
       this._placeholderBitmap = undefined;
       this._placeholder = undefined;
@@ -109,7 +112,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
   public showPlaceholder(value: boolean): void {
     if (value) {
       if (!this._placeholder && this.cellSize.height !== -1) {
-        this._createPlaceHolder(Math.max(this.cellSize.height + 1, PLACEHOLDER_HEIGHT));
+        this._createPlaceHolder(Math.max(this.cellSize.height + 1, Constants.PLACEHOLDER_HEIGHT));
       }
     } else {
       this._placeholderBitmap?.close();
@@ -140,27 +143,38 @@ export class ImageRenderer extends Disposable implements IDisposable {
   /**
    * Clear a region of the image layer canvas.
    */
-  public clearLines(start: number, end: number): void {
-    this._ctx?.clearRect(
-      0,
-      start * (this.dimensions?.css.cell.height || 0),
-      this.dimensions?.css.canvas.width || 0,
-      (++end - start) * (this.dimensions?.css.cell.height || 0)
-    );
+  public clearLines(start: number, end: number, layer?: ImageLayer): void {
+    const y = start * (this.dimensions?.css.cell.height || 0);
+    const w = this.dimensions?.css.canvas.width || 0;
+    const h = (end + 1 - start) * (this.dimensions?.css.cell.height || 0);
+    if (!layer || layer === 'top') {
+      this._layers.get('top')?.clearRect(0, y, w, h);
+    }
+    if (!layer || layer === 'bottom') {
+      this._layers.get('bottom')?.clearRect(0, y, w, h);
+    }
   }
 
   /**
    * Clear whole image canvas.
    */
-  public clearAll(): void {
-    this._ctx?.clearRect(0, 0, this.canvas?.width || 0, this.canvas?.height || 0);
+  public clearAll(layer?: ImageLayer): void {
+    if (!layer || layer === 'top') {
+      const ctx = this._layers.get('top');
+      ctx?.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+    }
+    if (!layer || layer === 'bottom') {
+      const ctx = this._layers.get('bottom');
+      ctx?.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+    }
   }
 
   /**
    * Draw neighboring tiles on the image layer canvas.
    */
   public draw(imgSpec: IImageSpec, tileId: number, col: number, row: number, count: number = 1): void {
-    if (!this._ctx) {
+    const ctx = this._layers.get(imgSpec.layer);
+    if (!ctx) {
       return;
     }
     const { width, height } = this.cellSize;
@@ -187,7 +201,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
     // Note: For not pixel perfect aligned cells like in the DOM renderer
     // this will move a tile slightly to the top/left (subpixel range, thus ignore it).
     // FIX #34: avoid striping on displays with pixelDeviceRatio != 1 by ceiling height and width
-    this._ctx.drawImage(
+    ctx.drawImage(
       img,
       Math.floor(sx), Math.floor(sy), Math.ceil(finalWidth), Math.ceil(finalHeight),
       Math.floor(dx), Math.floor(dy), Math.ceil(finalWidth), Math.ceil(finalHeight)
@@ -227,7 +241,8 @@ export class ImageRenderer extends Disposable implements IDisposable {
    * Draw a line with placeholder on the image layer canvas.
    */
   public drawPlaceholder(col: number, row: number, count: number = 1): void {
-    if (this._ctx) {
+    const ctx = this._layers.get('top');
+    if (ctx) {
       const { width, height } = this.cellSize;
 
       // Don't try to draw anything, if we cannot get valid renderer metrics.
@@ -236,12 +251,12 @@ export class ImageRenderer extends Disposable implements IDisposable {
       }
 
       if (!this._placeholder) {
-        this._createPlaceHolder(Math.max(height + 1, PLACEHOLDER_HEIGHT));
+        this._createPlaceHolder(Math.max(height + 1, Constants.PLACEHOLDER_HEIGHT));
       } else if (height >= this._placeholder!.height) {
         this._createPlaceHolder(height + 1);
       }
       if (!this._placeholder) return;
-      this._ctx.drawImage(
+      ctx.drawImage(
         this._placeholderBitmap ?? this._placeholder!,
         col * width,
         (row * height) % 2 ? 0 : 1,  // needs %2 offset correction
@@ -260,12 +275,13 @@ export class ImageRenderer extends Disposable implements IDisposable {
    * Checked once from `ImageStorage.render`.
    */
   public rescaleCanvas(): void {
-    if (!this.canvas) {
-      return;
-    }
-    if (this.canvas.width !== this.dimensions!.css.canvas.width || this.canvas.height !== this.dimensions!.css.canvas.height) {
-      this.canvas.width = this.dimensions!.css.canvas.width || 0;
-      this.canvas.height = this.dimensions!.css.canvas.height || 0;
+    const w = this.dimensions?.css.canvas.width || 0;
+    const h = this.dimensions?.css.canvas.height || 0;
+    for (const ctx of this._layers.values()) {
+      if (ctx.canvas.width !== w || ctx.canvas.height !== h) {
+        ctx.canvas.width = w;
+        ctx.canvas.height = h;
+      }
     }
   }
 
@@ -304,38 +320,68 @@ export class ImageRenderer extends Disposable implements IDisposable {
     this._renderService = this._terminal._core._renderService;
     this._oldSetRenderer = this._renderService.setRenderer.bind(this._renderService);
     this._renderService.setRenderer = (renderer: any) => {
-      this.removeLayerFromDom();
+      for (const key of [...this._layers.keys()]) {
+        this.removeLayerFromDom(key);
+      }
       this._oldSetRenderer?.call(this._renderService, renderer);
     };
   }
 
-  public insertLayerToDom(): void {
+  public insertLayerToDom(layer: ImageLayer = 'top'): void {
     // make sure that the terminal is attached to a document and to DOM
-    if (this.document && this._terminal._core.screenElement) {
-      if (!this.canvas) {
-        this.canvas = ImageRenderer.createCanvas(
-          this.document, this.dimensions?.css.canvas.width || 0,
-          this.dimensions?.css.canvas.height || 0
-        );
-        this.canvas.classList.add('xterm-image-layer');
-        this._terminal._core.screenElement.appendChild(this.canvas);
-        this._ctx = this.canvas.getContext('2d', { alpha: true, desynchronized: true });
-        this.clearAll();
-      }
-    } else {
+    if (!this.document || !this._terminal._core.screenElement) {
       console.warn('image addon: cannot insert output canvas to DOM, missing document or screenElement');
+      return;
+    }
+    if (this._layers.has(layer)) {
+      return;
+    }
+    const canvas = ImageRenderer.createCanvas(
+      this.document, this.dimensions?.css.canvas.width || 0,
+      this.dimensions?.css.canvas.height || 0
+    );
+    canvas.classList.add(`xterm-image-layer-${layer}`);
+    const screenElement = this._terminal._core.screenElement;
+    // Use isolation to create a stacking context without overriding z-index,
+    // which would conflict with integrators (e.g. VS Code) that set their
+    // own z-index on the screen element.
+    screenElement.style.isolation = 'isolate';
+    if (layer === 'bottom') {
+      // Use z-index:-1 so it paints behind non-positioned text elements.
+      // The screen element needs to be a stacking context (via isolation)
+      // to contain the negative z-index, otherwise it would go behind the
+      // entire terminal.
+      canvas.style.zIndex = '-1';
+      screenElement.insertBefore(canvas, screenElement.firstChild);
+    } else {
+      // Explicit z-index ensures the image canvas reliably stacks above
+      // the text layer (DOM renderer rows). z-index: 0 is below the
+      // selection overlay (z-index: 1).
+      canvas.style.zIndex = '0';
+      screenElement.appendChild(canvas);
+    }
+    const ctx = canvas.getContext('2d', { alpha: true });
+    if (!ctx) {
+      canvas.remove();
+      return;
+    }
+    this._layers.set(layer, ctx);
+    this.clearAll(layer);
+  }
+
+  public removeLayerFromDom(layer: ImageLayer = 'top'): void {
+    const ctx = this._layers.get(layer);
+    if (ctx) {
+      ctx.canvas.remove();
+      this._layers.delete(layer);
     }
   }
 
-  public removeLayerFromDom(): void {
-    if (this.canvas) {
-      this._ctx = undefined;
-      this.canvas.remove();
-      this.canvas = undefined;
-    }
+  public hasLayer(layer: ImageLayer): boolean {
+    return this._layers.has(layer);
   }
 
-  private _createPlaceHolder(height: number = PLACEHOLDER_HEIGHT): void {
+  private _createPlaceHolder(height: number = Constants.PLACEHOLDER_HEIGHT): void {
     this._placeholderBitmap?.close();
     this._placeholderBitmap = undefined;
 
@@ -359,7 +405,7 @@ export class ImageRenderer extends Disposable implements IDisposable {
     ctx.putImageData(imgData, 0, 0);
 
     // create placeholder line, width aligned to blueprint width
-    const width = (screen.width + bWidth - 1) & ~(bWidth - 1) || PLACEHOLDER_LENGTH;
+    const width = (screen.width + bWidth - 1) & ~(bWidth - 1) || Constants.PLACEHOLDER_LENGTH;
     this._placeholder = ImageRenderer.createCanvas(this.document, width, height);
     const ctx2 = this._placeholder.getContext('2d', { alpha: false });
     if (!ctx2) {

addons/addon-image/src/ImageStorage.ts

@@ -5,7 +5,11 @@
 
 import { IDisposable } from '@xterm/xterm';
 import { ImageRenderer } from './ImageRenderer';
-import { ITerminalExt, IExtendedAttrsImage, IImageAddonOptions, IImageSpec, IBufferLineExt, BgFlags, Cell, Content, ICellSize, ExtFlags, Attributes, UnderlineStyle } from './Types';
+import {
+  ITerminalExt, IExtendedAttrsImage, IImageAddonOptions, IImageSpec,
+  IBufferLineExt, BgFlags, Cell, Content, ICellSize, ExtFlags, Attributes,
+  UnderlineStyle, IAddImageOpts
+} from './Types';
 
 
 // fallback default cell size
@@ -124,6 +128,8 @@ export class ImageStorage implements IDisposable {
   private _pixelLimit: number = 2500000;
 
   private _viewportMetrics: { cols: number, rows: number };
+  public onImageAdded: (() => void) | undefined;
+  public onImageDeleted: ((storageId: number) => void) | undefined;
 
   constructor(
     private _terminal: ITerminalExt,
@@ -189,11 +195,13 @@ export class ImageStorage implements IDisposable {
 
   private _delImg(id: number): void {
     const spec = this._images.get(id);
+    if (!spec) return;
     this._images.delete(id);
     // FIXME: really ugly workaround to get bitmaps deallocated :(
-    if (spec && window.ImageBitmap && spec.orig instanceof ImageBitmap) {
+    if (window.ImageBitmap && spec.orig instanceof ImageBitmap) {
       spec.orig.close();
     }
+    this.onImageDeleted?.(id);
   }
 
   /**
@@ -217,27 +225,29 @@ export class ImageStorage implements IDisposable {
   }
 
   /**
-   * Only advance text cursor.
-   * This is an edge case from empty sixels carrying only a height but no pixels.
-   * Partially fixes https://github.com/jerch/xterm-addon-image/issues/37.
+   * Delete an image by its internal storage ID.
+   * Used by protocols that support explicit deletion (e.g. Kitty a=d).
    */
-  public advanceCursor(height: number): void {
-    if (this._opts.sixelScrolling) {
-      let cellSize = this._renderer.cellSize;
-      if (cellSize.width === -1 || cellSize.height === -1) {
-        cellSize = CELL_SIZE_DEFAULT;
-      }
-      const rows = Math.ceil(height / cellSize.height);
-      for (let i = 1; i < rows; ++i) {
-        this._terminal._core._inputHandler.lineFeed();
-      }
+  public deleteImage(id: number): void {
+    const spec = this._images.get(id);
+    if (spec) {
+      spec.marker?.dispose();
+      this._delImg(id);
     }
   }
 
   /**
    * Method to add an image to the storage.
+   * @param img - The image to add (canvas or bitmap).
+   * @param opts - Options for addImage:
+   *   - scrolling:  When true, cursor advances with the image.
+   *                 When false, image is placed at ORIGIN and cursor does not move.
+   *   - layer:      Which canvas layer to render on ('top' or 'bottom').
+   *   - zIndex:     Z-index for image layering within the same layer.
+   *   - cursorPos:  'vt340' for bottom-left, 'iip' for bottom.right.
+   * @returns The internal image ID assigned to the stored image.
    */
-  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+  public addImage(img: HTMLCanvasElement | ImageBitmap, opts: IAddImageOpts): number {
     // never allow storage to exceed memory limit
     this._evictOldest(img.width * img.height);
 
@@ -259,7 +269,7 @@ export class ImageStorage implements IDisposable {
     let offset = originX;
     let tileCount = 0;
 
-    if (!this._opts.sixelScrolling) {
+    if (!opts.scrolling) {
       buffer.x = 0;
       buffer.y = 0;
       offset = 0;
@@ -273,7 +283,7 @@ export class ImageStorage implements IDisposable {
         this._writeToCell(line as IBufferLineExt, offset + col, imageId, row * cols + col);
         tileCount++;
       }
-      if (this._opts.sixelScrolling) {
+      if (opts.scrolling) {
         if (row < rows - 1) this._terminal._core._inputHandler.lineFeed();
       } else {
         if (++buffer.y >= termRows) break;
@@ -283,8 +293,12 @@ export class ImageStorage implements IDisposable {
     this._terminal._core._inputHandler._dirtyRowTracker.markDirty(buffer.y);
 
     // cursor positioning modes
-    if (this._opts.sixelScrolling) {
-      buffer.x = offset;
+    if (opts.scrolling) {
+      if (opts.cursorPos === 'iip') {
+        buffer.x = Math.min(offset + cols, termCols);
+      } else {
+        buffer.x = offset;
+      }
     } else {
       buffer.x = originX;
       buffer.y = originY;
@@ -326,11 +340,15 @@ export class ImageStorage implements IDisposable {
       actualCellSize: { ...cellSize },  // clone needed, since later modified
       marker: endMarker || undefined,
       tileCount,
-      bufferType: this._terminal.buffer.active.type
+      bufferType: this._terminal.buffer.active.type,
+      layer: opts.layer,
+      zIndex: opts.zIndex
     };
 
     // finally add the image
     this._images.set(imageId, imgSpec);
+    this.onImageAdded?.();
+    return imageId;
   }
 
 
@@ -340,16 +358,30 @@ export class ImageStorage implements IDisposable {
    */
   // TODO: Should we move this to the ImageRenderer?
   public render(range: { start: number, end: number }): void {
-    // setup image canvas in case we have none yet, but have images in store
-    if (!this._renderer.canvas && this._images.size) {
-      this._renderer.insertLayerToDom();
-      // safety measure - in case we cannot spawn a canvas at all, just exit
-      if (!this._renderer.canvas) {
-        return;
+    // Determine which layers have images
+    let hasTopImages = false;
+    let hasBottomImages = false;
+    for (const spec of this._images.values()) {
+      if (spec.layer === 'bottom') {
+        hasBottomImages = true;
+      } else {
+        hasTopImages = true;
       }
+      if (hasTopImages && hasBottomImages) break;
     }
+
+    // Lazily insert layers that are needed
+    if (hasTopImages && !this._renderer.hasLayer('top')) {
+      this._renderer.insertLayerToDom('top');
+      if (!this._renderer.hasLayer('top')) return;
+    }
+    if (hasBottomImages && !this._renderer.hasLayer('bottom')) {
+      this._renderer.insertLayerToDom('bottom');
+    }
+
     // rescale if needed
     this._renderer.rescaleCanvas();
+
     // exit early if we dont have any images to test for
     if (!this._images.size) {
       if (!this._fullyCleared) {
@@ -357,12 +389,25 @@ export class ImageStorage implements IDisposable {
         this._fullyCleared = true;
         this._needsFullClear = false;
       }
-      if (this._renderer.canvas) {
-        this._renderer.removeLayerFromDom();
+      if (this._renderer.hasLayer('top')) {
+        this._renderer.removeLayerFromDom('top');
+      }
+      if (this._renderer.hasLayer('bottom')) {
+        this._renderer.removeLayerFromDom('bottom');
       }
       return;
     }
 
+    // Remove layers no longer needed
+    if (!hasTopImages && this._renderer.hasLayer('top')) {
+      this._renderer.clearAll('top');
+      this._renderer.removeLayerFromDom('top');
+    }
+    if (!hasBottomImages && this._renderer.hasLayer('bottom')) {
+      this._renderer.clearAll('bottom');
+      this._renderer.removeLayerFromDom('bottom');
+    }
+
     // buffer switches force a full clear
     if (this._needsFullClear) {
       this._renderer.clearAll();
@@ -377,50 +422,76 @@ export class ImageStorage implements IDisposable {
     // clear drawing area
     this._renderer.clearLines(start, end);
 
-    // walk all cells in viewport and draw tiles found
+    // Collect draw calls so we can sort by z-index (lower z drawn first).
+    const drawCalls: { imgSpec: IImageSpec, tileId: number, col: number, row: number, count: number }[] = [];
+    const placeholderCalls: { col: number, row: number, count: number }[] = [];
+
+    // walk all cells in viewport and collect tiles found
+    // Note: We check _extendedAttrs directly (not just HAS_EXTENDED flag)
+    // because text writes clear the BG flag but leave image tile data intact.
+    // This lets top-layer images survive text overwrites (kitty C=1 behavior).
     for (let row = start; row <= end; ++row) {
       const line = buffer.lines.get(row + buffer.ydisp) as IBufferLineExt;
       if (!line) return;
       for (let col = 0; col < cols; ++col) {
+        let e: IExtendedAttrsImage;
         if (line.getBg(col) & BgFlags.HAS_EXTENDED) {
-          let e: IExtendedAttrsImage = line._extendedAttrs[col] ?? EMPTY_ATTRS;
-          const imageId = e.imageId;
-          if (imageId === undefined || imageId === -1) {
+          e = line._extendedAttrs[col] ?? EMPTY_ATTRS;
+        } else {
+          const maybeImg = line._extendedAttrs[col] as IExtendedAttrsImage | undefined;
+          if (!maybeImg || maybeImg.imageId === undefined || maybeImg.imageId === -1) {
             continue;
           }
-          const imgSpec = this._images.get(imageId);
-          if (e.tileId !== -1) {
-            const startTile = e.tileId;
-            const startCol = col;
-            let count = 1;
-            /**
-             * merge tiles to the right into a single draw call, if:
-             * - not at end of line
-             * - cell has same image id
-             * - cell has consecutive tile id
-             */
-            while (
-              ++col < cols
-              && (line.getBg(col) & BgFlags.HAS_EXTENDED)
-              && (e = line._extendedAttrs[col] ?? EMPTY_ATTRS)
-              && (e.imageId === imageId)
-              && (e.tileId === startTile + count)
-            ) {
-              count++;
+          e = maybeImg;
+        }
+        const imageId = e.imageId;
+        if (imageId === undefined || imageId === -1) {
+          continue;
+        }
+        const imgSpec = this._images.get(imageId);
+        if (e.tileId !== -1) {
+          const startTile = e.tileId;
+          const startCol = col;
+          let count = 1;
+          /**
+           * merge tiles to the right into a single draw call, if:
+           * - not at end of line
+           * - cell has same image id
+           * - cell has consecutive tile id
+           * Also check _extendedAttrs directly for cells where text cleared HAS_EXTENDED.
+           */
+          while (++col < cols) {
+            const nextE = line._extendedAttrs[col] as IExtendedAttrsImage | undefined;
+            if (!nextE || nextE.imageId !== imageId || nextE.tileId !== startTile + count) {
+              break;
             }
-            col--;
-            if (imgSpec) {
-              if (imgSpec.actual) {
-                this._renderer.draw(imgSpec, startTile, startCol, row, count);
-              }
-            } else if (this._opts.showPlaceholder) {
-              this._renderer.drawPlaceholder(startCol, row, count);
-            }
-            this._fullyCleared = false;
+            count++;
           }
+          col--;
+          if (imgSpec) {
+            if (imgSpec.actual) {
+              drawCalls.push({ imgSpec, tileId: startTile, col: startCol, row, count });
+            }
+          } else if (this._opts.showPlaceholder) {
+            placeholderCalls.push({ col: startCol, row, count });
+          }
+          this._fullyCleared = false;
         }
       }
     }
+
+    // Sort by z-index so lower z draws first (higher z renders on top)
+    drawCalls.sort((a, b) => a.imgSpec.zIndex - b.imgSpec.zIndex);
+
+    // Draw placeholders first (lowest priority)
+    for (const call of placeholderCalls) {
+      this._renderer.drawPlaceholder(call.col, call.row, call.count);
+    }
+
+    // Draw images in z-index order
+    for (const call of drawCalls) {
+      this._renderer.draw(call.imgSpec, call.tileId, call.col, call.row, call.count);
+    }
   }
 
   public viewportResize(metrics: { cols: number, rows: number }): void {

addons/addon-image/src/SixelHandler.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { ImageStorage } from './ImageStorage';
+import { SixelImageStorage } from './SixelImageStorage';
 import { IDcsHandler, IParams, IImageAddonOptions, ITerminalExt, AttributeData, IResetHandler, ReadonlyColorSet } from './Types';
 import { toRGBA8888, BIG_ENDIAN, PALETTE_ANSI_256, PALETTE_VT340_COLOR } from 'sixel/lib/Colors';
 import { RGBA8888 } from 'sixel/lib/Types';
@@ -26,7 +26,7 @@ export class SixelHandler implements IDcsHandler, IResetHandler {
 
   constructor(
     private readonly _opts: IImageAddonOptions,
-    private readonly _storage: ImageStorage,
+    private readonly _storage: SixelImageStorage,
     private readonly _coreTerminal: ITerminalExt
   ) {
     DecoderAsync({
@@ -91,7 +91,7 @@ export class SixelHandler implements IDcsHandler, IResetHandler {
     const height = this._dec.height;
 
     // partial fix for https://github.com/jerch/xterm-addon-image/issues/37
-    if (!width || ! height) {
+    if (!width || !height) {
       if (height) {
         this._storage.advanceCursor(height);
       }

addons/addon-image/src/SixelImageStorage.ts

@@ -0,0 +1,52 @@
+/**
+ * Copyright (c) 2020 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { ImageStorage, CELL_SIZE_DEFAULT } from './ImageStorage';
+import { IImageAddonOptions, ITerminalExt, IAddImageOpts } from './Types';
+import { ImageRenderer } from './ImageRenderer';
+
+/**
+ * Sixel-specific image storage controller.
+ *
+ * Wraps the shared ImageStorage with sixel protocol semantics:
+ * - Cursor behavior governed by DECSET 80 (sixelScrolling option)
+ * - advanceCursor for empty sixels carrying only height
+ */
+export class SixelImageStorage {
+  private _addImageOpts: IAddImageOpts = { scrolling: true, layer: 'top', zIndex: 0, cursorPos: 'vt340' };
+  constructor(
+    private readonly _storage: ImageStorage,
+    private readonly _opts: IImageAddonOptions,
+    private readonly _renderer: ImageRenderer,
+    private readonly _terminal: ITerminalExt
+  ) {}
+
+  /**
+   * Add a sixel image to storage.
+   * Cursor behavior depends on the sixelScrolling option (DECSET 80).
+   */
+  public addImage(img: HTMLCanvasElement | ImageBitmap): void {
+    this._addImageOpts.scrolling = this._opts.sixelScrolling;
+    this._storage.addImage(img, this._addImageOpts);
+  }
+
+  /**
+   * Only advance text cursor.
+   * This is an edge case from empty sixels carrying only a height but no pixels.
+   * Partially fixes https://github.com/jerch/xterm-addon-image/issues/37.
+   */
+  public advanceCursor(height: number): void {
+    if (this._opts.sixelScrolling) {
+      let cellSize = this._renderer.cellSize;
+      if (cellSize.width === -1 || cellSize.height === -1) {
+        cellSize = CELL_SIZE_DEFAULT;
+      }
+      const rows = Math.ceil(height / cellSize.height);
+      for (let i = 1; i < rows; ++i) {
+        this._terminal._core._inputHandler.lineFeed();
+      }
+    }
+  }
+}

addons/addon-image/src/Types.ts

@@ -8,7 +8,7 @@ import { IDisposable, IMarker, Terminal } from '@xterm/xterm';
 // private imports from base repo we build against
 import { Attributes, BgFlags, Content, ExtFlags, UnderlineStyle } from 'common/buffer/Constants';
 import type { AttributeData } from 'common/buffer/AttributeData';
-import type { IParams, IDcsHandler, IOscHandler, IEscapeSequenceParser } from 'common/parser/Types';
+import type { IParams, IDcsHandler, IOscHandler, IApcHandler, IEscapeSequenceParser } from 'common/parser/Types';
 import type { IBufferLine, IExtendedAttrs, IInputHandler } from 'common/Types';
 import type { ITerminal, ReadonlyColorSet } from 'browser/Types';
 import type { IRenderDimensions } from 'browser/renderer/shared/Types';
@@ -22,7 +22,7 @@ export const enum Cell {
 }
 
 // export some privates for local usage
-export { AttributeData, IParams, IDcsHandler, IOscHandler, BgFlags, IRenderDimensions, IRenderService, Content, ExtFlags, Attributes, UnderlineStyle, ReadonlyColorSet };
+export { AttributeData, IParams, IDcsHandler, IOscHandler, IApcHandler, BgFlags, IRenderDimensions, IRenderService, Content, ExtFlags, Attributes, UnderlineStyle, ReadonlyColorSet };
 
 /**
  * Plugin ctor options.
@@ -38,6 +38,8 @@ export interface IImageAddonOptions {
   sixelSizeLimit: number;
   iipSupport: boolean;
   iipSizeLimit: number;
+  kittySupport: boolean;
+  kittySizeLimit: number;
 }
 
 export interface IResetHandler {
@@ -97,6 +99,16 @@ export interface ICellSize {
   height: number;
 }
 
+export type ImageLayer = 'top' | 'bottom';
+export type CursorPos = 'vt340' | 'iip';
+
+export interface IAddImageOpts {
+  scrolling: boolean;
+  layer: ImageLayer;
+  zIndex: number;
+  cursorPos: CursorPos;
+}
+
 export interface IImageSpec {
   orig: HTMLCanvasElement | ImageBitmap | undefined;
   origCellSize: ICellSize;
@@ -105,4 +117,6 @@ export interface IImageSpec {
   marker: IMarker | undefined;
   tileCount: number;
   bufferType: 'alternate' | 'normal';
+  layer: ImageLayer;
+  zIndex: number;
 }

addons/addon-image/src/kitty/KittyGraphicsHandler.ts

@@ -0,0 +1,819 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IDisposable } from '@xterm/xterm';
+import { IApcHandler, IImageAddonOptions, IResetHandler, ITerminalExt, ImageLayer } from '../Types';
+import { ImageRenderer } from '../ImageRenderer';
+import { CELL_SIZE_DEFAULT } from '../ImageStorage';
+import { KittyImageStorage } from './KittyImageStorage';
+import Base64Decoder, { type DecodeStatus } from 'xterm-wasm-parts/lib/base64/Base64Decoder.wasm';
+import {
+  KittyAction,
+  KittyFormat,
+  KittyCompression,
+  IKittyCommand,
+  IPendingTransmission,
+  IKittyImageData,
+  KittyPixelConstants,
+  parseKittyCommand
+} from './KittyGraphicsTypes';
+
+const enum Constants {
+  // Memory limit for base64 decoder (4MB, same as IIPHandler)
+  DECODER_KEEP_DATA = 4194304,
+  DECODER_INITIAL_DATA = 4194304, // 4MB
+  // Local mirror of const enum (esbuild can't inline const enums from external packages)
+  DECODER_OK = 0,
+  // Maximum control data size
+  MAX_CONTROL_DATA_SIZE = 512,
+  // Semicolon codepoint
+  SEMICOLON = 0x3B
+}
+
+const DECODER_OK = Constants.DECODER_OK as unknown as DecodeStatus.OK;
+
+// Kitty graphics protocol handler with streaming base64 decoding.
+export class KittyGraphicsHandler implements IApcHandler, IResetHandler, IDisposable {
+  private _aborted = false;
+  private _decodeError = false;
+
+  private _activeDecoder: Base64Decoder | null = null;
+  private readonly _maxEncodedBytes: number;
+  private readonly _initialEncodedBytes: number;
+
+  // Streaming related states
+
+  // True while receiving control data (before semicolon).
+  private _inControlData = true;
+
+  // Buffer for control data.
+  private _controlData = new Uint32Array(Constants.MAX_CONTROL_DATA_SIZE);
+  private _controlLength = 0;
+
+  // Pre-calculated encoded size limit
+  private _encodedSizeLimit = 0;
+  private _totalEncodedSize = 0;
+
+  // Parsed command. These are the control data before semicolon.
+  private _parsedCommand: IKittyCommand | null = null;
+
+  // Storage related states
+
+  private _pendingTransmissions: Map<number, IPendingTransmission> = new Map();
+  // Tracks the pending key of the most recently started chunked upload.
+  // Per spec, subsequent chunks only need m= (and optionally q=), without i=.
+  // When a chunk arrives with no i=, this key is used to find the pending upload.
+  private _lastPendingKey: number | undefined;
+
+  constructor(
+    private readonly _opts: IImageAddonOptions,
+    private readonly _renderer: ImageRenderer,
+    private readonly _kittyStorage: KittyImageStorage,
+    private readonly _coreTerminal: ITerminalExt
+  ) {
+    // Convert decoded size limit -> max encoded bytes.
+    this._maxEncodedBytes = Math.ceil(this._opts.kittySizeLimit * 4 / 3);
+    // ensure we preallocate more than configured limit while using 4mb initial size.
+    this._initialEncodedBytes = Math.min(Constants.DECODER_INITIAL_DATA, this._maxEncodedBytes);
+  }
+
+  public reset(): void {
+    this._cleanupAllPending();
+    if (this._activeDecoder) {
+      this._activeDecoder.release();
+      this._activeDecoder = null;
+    }
+    this._kittyStorage.reset();
+  }
+
+  public dispose(): void {
+    this.reset();
+  }
+
+  private _removePendingEntry(key: number): void {
+    this._pendingTransmissions.delete(key);
+    if (this._lastPendingKey === key) {
+      this._lastPendingKey = undefined;
+    }
+  }
+
+  private _cleanupAllPending(): void {
+    for (const pending of this._pendingTransmissions.values()) {
+      pending.decoder.release();
+    }
+    this._pendingTransmissions.clear();
+    this._lastPendingKey = undefined;
+  }
+
+  public start(): void {
+    this._aborted = false;
+    this._decodeError = false;
+    this._inControlData = true;
+    this._controlLength = 0;
+    this._parsedCommand = null;
+    // Pre-calculate encoded limit once: base64 is 4 bytes encoded → 3 bytes decoded
+    this._encodedSizeLimit = this._maxEncodedBytes;
+    this._totalEncodedSize = 0;
+    this._activeDecoder = null;
+  }
+
+  public put(data: Uint32Array, start: number, end: number): void {
+    if (this._aborted) return;
+
+    if (!this._inControlData) {
+      this._streamPayload(data, start, end);
+    } else {
+      // Scan for semicolon
+      let controlEnd = end;
+      for (let i = start; i < end; i++) {
+        if (data[i] === Constants.SEMICOLON) {
+          this._inControlData = false;
+          controlEnd = i;
+          break;
+        }
+      }
+
+      // Copy control data
+      const copyLength = controlEnd - start;
+      if (this._controlLength + copyLength > Constants.MAX_CONTROL_DATA_SIZE) {
+        this._aborted = true;
+        return;
+      }
+      this._controlData.set(data.subarray(start, controlEnd), this._controlLength);
+      this._controlLength += copyLength;
+
+      if (!this._inControlData) {
+        // Found semicolon - parse control data early for validation
+        this._parsedCommand = parseKittyCommand(this._parseControlDataString());
+
+        // Early validation: i+I conflict
+        if (this._parsedCommand.id !== undefined && this._parsedCommand.imageNumber !== undefined) {
+          this._sendResponse(this._parsedCommand.id, 'EINVAL:cannot specify both i and I keys', this._parsedCommand.quiet ?? 0);
+          this._aborted = true;
+          return;
+        }
+
+        // Delete action doesn't need payload - skip streaming
+        if (this._parsedCommand.action === KittyAction.DELETE) {
+          return;
+        }
+
+        // Stream remaining as payload
+        const payloadStart = controlEnd + 1;
+        if (payloadStart < end) {
+          this._streamPayload(data, payloadStart, end);
+        }
+      }
+    }
+  }
+
+  // Stream payload bytes into the base64 decoder.
+  private _streamPayload(data: Uint32Array, start: number, end: number): void {
+    if (this._aborted) return;
+
+    // Check size limit (compare encoded bytes against pre-calculated limit)
+    // Include cumulative size from pending transmission for multi-chunk images.
+    // Per spec, subsequent chunks may omit i=, so fall back to _lastPendingKey.
+    const pendingKey = this._parsedCommand?.id ?? this._lastPendingKey ?? 0;
+    const pending = this._pendingTransmissions.get(pendingKey);
+    const previousEncodedSize = pending?.totalEncodedSize ?? 0;
+    this._totalEncodedSize += end - start;
+    const cumulativeEncodedSize = previousEncodedSize + this._totalEncodedSize;
+    if (cumulativeEncodedSize > this._encodedSizeLimit) {
+      const decoderToRelease = this._activeDecoder ?? pending?.decoder;
+      if (decoderToRelease) {
+        decoderToRelease.release();
+      }
+      this._activeDecoder = null;
+      if (pending) {
+        this._removePendingEntry(pendingKey);
+      }
+      this._aborted = true;
+      return;
+    }
+
+    if (this._decodeError) return;
+
+    if (pending?.decoder && !this._activeDecoder) {
+      this._activeDecoder = pending.decoder;
+    }
+    if (!this._activeDecoder) {
+      this._activeDecoder = new Base64Decoder(Constants.DECODER_KEEP_DATA, this._maxEncodedBytes, this._initialEncodedBytes);
+      this._activeDecoder.init();
+    }
+
+    if (this._activeDecoder.put(data.subarray(start, end)) !== DECODER_OK) {
+      this._activeDecoder.release();
+      this._activeDecoder = null;
+      this._decodeError = true;
+      if (pending) {
+        this._removePendingEntry(pendingKey);
+      }
+    }
+  }
+
+  public end(success: boolean): boolean | Promise<boolean> {
+    if (this._aborted || !success) {
+      if (this._activeDecoder) {
+        this._activeDecoder.release();
+        this._activeDecoder = null;
+      }
+      return true;
+    }
+
+    // No semicolon = no payload (delete, capability query)
+    if (this._inControlData) {
+      return this._handleNoPayloadCommand();
+    }
+
+    // Use command parsed early in put() - i+I already validated there
+    const cmd = this._parsedCommand!;
+
+    // Delete action was handled by skipping payload - just execute
+    if (cmd.action === KittyAction.DELETE) {
+      return this._handleDelete(cmd);
+    }
+
+    // Per spec, subsequent chunks may omit i=, so fall back to _lastPendingKey.
+    const pendingKey = cmd.id ?? this._lastPendingKey ?? 0;
+    const isMoreComing = cmd.more === 1;
+    const pending = this._pendingTransmissions.get(pendingKey);
+
+    if (isMoreComing) {
+      if (this._activeDecoder) {
+        if (pending) {
+          pending.totalEncodedSize += this._totalEncodedSize;
+          pending.decodeError = pending.decodeError || this._decodeError;
+        } else {
+          this._pendingTransmissions.set(pendingKey, {
+            cmd: { ...cmd },
+            decoder: this._activeDecoder,
+            totalEncodedSize: this._totalEncodedSize,
+            decodeError: this._decodeError
+          });
+        }
+        this._lastPendingKey = pendingKey;
+        this._activeDecoder = null;
+      }
+      return true;
+    }
+
+    // Final chunk received — clear the last pending key
+    if (pending) {
+      this._lastPendingKey = undefined;
+    }
+
+    let decodeError = this._decodeError;
+    let finalCmd = cmd;
+    let decoder = this._activeDecoder;
+
+    if (pending) {
+      finalCmd = pending.cmd;
+      decoder = pending.decoder;
+      decodeError = decodeError || pending.decodeError;
+      this._pendingTransmissions.delete(pendingKey);
+    }
+
+    let imageBytes = new Uint8Array(0);
+    if (decoder) {
+      if (decoder.end() !== DECODER_OK) {
+        decodeError = true;
+      }
+      imageBytes = decoder.data8;
+    }
+    this._activeDecoder = null;
+
+    // Handle command first — handlers create Blob/ImageData from imageBytes,
+    // which copies the data. Only then is it safe to release the decoder's
+    // wasm memory that imageBytes points into.
+    const result = this._handleCommandWithBytesAndCmd(finalCmd, imageBytes, decodeError);
+    if (decoder) {
+      decoder.release();
+    }
+    return result;
+  }
+
+  // Command handling
+
+  private _parseControlDataString(): string {
+    let str = '';
+    for (let i = 0; i < this._controlLength; i++) {
+      str += String.fromCodePoint(this._controlData[i]);
+    }
+    return str;
+  }
+
+  private _handleNoPayloadCommand(): boolean | Promise<boolean> {
+    const cmd = parseKittyCommand(this._parseControlDataString());
+
+    // Per spec: specifying both i and I is an error
+    if (cmd.id !== undefined && cmd.imageNumber !== undefined) {
+      this._sendResponse(cmd.id, 'EINVAL:cannot specify both i and I keys', cmd.quiet ?? 0);
+      return true;
+    }
+
+    const action = cmd.action ?? 't';
+
+    switch (action) {
+      case KittyAction.DELETE:
+        return this._handleDelete(cmd);
+      case KittyAction.QUERY:
+        this._sendResponse(cmd.id ?? 0, 'OK', cmd.quiet ?? 0);
+        return true;
+      case KittyAction.PLACEMENT:
+        return this._handlePlacement(cmd);
+      default:
+        // TODO: Implement remaining actions when needed:
+        // - a=f (frame): animation frame operations
+        // - a=a (animation): animation control
+        // - a=c (compose): compose images
+        if (cmd.id !== undefined) {
+          this._sendResponse(cmd.id, 'EINVAL:unsupported action', cmd.quiet ?? 0);
+        }
+        return true;
+    }
+  }
+
+  private _handleCommandWithBytesAndCmd(cmd: IKittyCommand, bytes: Uint8Array, decodeError: boolean): boolean | Promise<boolean> {
+    const action = cmd.action ?? 't';
+
+    switch (action) {
+      case KittyAction.TRANSMIT: {
+        const result = this._handleTransmit(cmd, bytes, decodeError);
+        // Only send response when _handleTransmit didn't already respond
+        // (it handles unsupported transmission medium responses internally)
+        if ((cmd.transmission ?? 'd') === 'd' && cmd.id !== undefined) {
+          if (decodeError) {
+            this._sendResponse(cmd.id, 'EINVAL:invalid base64 data', cmd.quiet ?? 0);
+          } else if (bytes.length > 0) {
+            this._sendResponse(cmd.id, 'OK', cmd.quiet ?? 0);
+          }
+        }
+        return result;
+      }
+      case KittyAction.TRANSMIT_DISPLAY:
+        return this._handleTransmitDisplay(cmd, bytes, decodeError);
+      case KittyAction.QUERY:
+        return this._handleQuery(cmd, bytes, decodeError);
+      case KittyAction.PLACEMENT:
+        // a=p ignores any payload — image data was already transmitted
+        return this._handlePlacement(cmd);
+      default:
+        // TODO: Implement remaining actions when needed:
+        // - a=f (frame): animation frame operations
+        // - a=a (animation): animation control
+        // - a=c (compose): compose images
+        if (cmd.id !== undefined) {
+          this._sendResponse(cmd.id, 'EINVAL:unsupported action', cmd.quiet ?? 0);
+        }
+        return true;
+    }
+  }
+
+  private _handlePlacement(cmd: IKittyCommand): boolean | Promise<boolean> {
+    if (cmd.id === undefined) {
+      return true;
+    }
+    const id = cmd.id;
+    const image = this._kittyStorage.getImage(id);
+    if (!image) {
+      this._sendResponse(id, 'ENOENT:image not found', cmd.quiet ?? 0, cmd.placementId);
+      return true;
+    }
+    const result = this._displayImage(image, cmd);
+    return result.then(success => {
+      this._sendResponse(id, success ? 'OK' : 'EINVAL:image rendering failed', cmd.quiet ?? 0, cmd.placementId);
+      return true;
+    });
+  }
+
+  private _handleTransmit(cmd: IKittyCommand, bytes: Uint8Array, decodeError: boolean): boolean {
+    // TODO: Support file-based transmission modes (t=f, t=t, t=s)
+    // Currently only supports direct transmission (t=d, the default).
+    // - t=f (file): Payload is base64-encoded file path. Terminal reads image from that path.
+    // - t=t (temp file): Payload is base64-encoded path in temp directory. Terminal reads, deletes.
+    // - t=s: Payload is base64-encoded POSIX shm name. Terminal reads from shared memory.
+    // These modes require filesystem/IPC access not available in browsers. For Node.js/Electron:
+    // 1. Check cmd.transmission (t key) before treating bytes as image data
+    // 2. For t=f/t/s: decode bytes as UTF-8 string (the path/name), then read file contents
+    // 3. For t=d: treat bytes as image data (current behavior)
+    // When implementing, also update _handleQuery to accept these transmission mediums.
+    const transmission = cmd.transmission ?? 'd';
+    if (transmission !== 'd') {
+      if (cmd.id !== undefined) {
+        this._sendResponse(cmd.id, 'EINVAL:unsupported transmission medium', cmd.quiet ?? 0);
+      }
+      return true;
+    }
+
+    if (decodeError || bytes.length === 0) return true;
+
+    this._kittyStorage.storeImage(cmd.id, {
+      data: new Blob([bytes as BlobPart]),
+      width: cmd.width ?? 0,
+      height: cmd.height ?? 0,
+      format: (cmd.format ?? KittyFormat.RGBA) as 24 | 32 | 100,
+      compression: cmd.compression ?? ''
+    });
+    return true;
+  }
+
+  private _handleTransmitDisplay(cmd: IKittyCommand, bytes: Uint8Array, decodeError: boolean): boolean | Promise<boolean> {
+    if (decodeError) {
+      if (cmd.id !== undefined) {
+        this._sendResponse(cmd.id, 'EINVAL:invalid base64 data', cmd.quiet ?? 0);
+      }
+      return true;
+    }
+
+    this._handleTransmit(cmd, bytes, decodeError);
+
+    const id = cmd.id ?? this._kittyStorage.lastImageId;
+    const image = this._kittyStorage.getImage(id);
+    if (image) {
+      const result = this._displayImage(image, cmd);
+      if (cmd.id !== undefined) {
+        return result.then(success => {
+          this._sendResponse(id, success ? 'OK' : 'EINVAL:image rendering failed', cmd.quiet ?? 0);
+          return true;
+        });
+      }
+      return result.then(() => true);
+    }
+    return true;
+  }
+
+  private _handleQuery(cmd: IKittyCommand, bytes: Uint8Array, decodeError: boolean): boolean {
+    const id = cmd.id ?? 0;
+    const quiet = cmd.quiet ?? 0;
+
+    // Per spec: reject unsupported transmission mediums (only t=d is supported atm)
+    // TODO: When filesystem support is added (Node.js/Electron), update this to accept
+    // t=f (file), t=t (temp file), and t=s (shared memory) and respond OK for queries.
+    const transmission = cmd.transmission ?? 'd';
+    if (transmission !== 'd') {
+      this._sendResponse(id, 'EINVAL:unsupported transmission medium', quiet);
+      return true;
+    }
+
+    // Check decode error first (invalid base64)
+    if (decodeError) {
+      this._sendResponse(id, 'EINVAL:invalid base64 data', quiet);
+      return true;
+    }
+
+    // Capability query (no payload) - just respond OK
+    if (bytes.length === 0) {
+      this._sendResponse(id, 'OK', quiet);
+      return true;
+    }
+
+    const format = cmd.format ?? KittyFormat.RGBA;
+
+    if (format === KittyFormat.PNG) {
+      this._sendResponse(id, 'OK', quiet);
+    } else {
+      const width = cmd.width ?? 0;
+      const height = cmd.height ?? 0;
+
+      if (!width || !height) {
+        this._sendResponse(id, 'EINVAL:width and height required for raw pixel data', quiet);
+        return true;
+      }
+
+      const bytesPerPixel = format === KittyFormat.RGBA ? KittyPixelConstants.BYTES_PER_PIXEL_RGBA : KittyPixelConstants.BYTES_PER_PIXEL_RGB;
+      const expectedBytes = width * height * bytesPerPixel;
+
+      if (bytes.length < expectedBytes) {
+        this._sendResponse(id, `EINVAL:insufficient pixel data`, quiet);
+        return true;
+      }
+
+      this._sendResponse(id, 'OK', quiet);
+    }
+    return true;
+  }
+
+  private _handleDelete(cmd: IKittyCommand): boolean {
+    // Per spec: default delete selector is 'a' (delete all visible placements)
+    const selector = cmd.deleteSelector ?? 'a';
+
+    // TODO: Distinguish lowercase (delete placements only) from uppercase
+    // (delete placements + free stored image data). Currently both variants
+    // free everything since we don't separate stored data from placements.
+    switch (selector) {
+      case 'a':
+      case 'A':
+        this._cleanupAllPending();
+        this._kittyStorage.deleteAll();
+        break;
+      case 'i':
+      case 'I':
+        // TODO: When placement id tracking is implemented (see TODO in
+        // KittyImageStorage), d=i with p=<pid> should delete only that
+        // specific placement, while d=i without p should delete all
+        // placements for the image.
+        if (cmd.id !== undefined) {
+          const pending = this._pendingTransmissions.get(cmd.id);
+          if (pending) {
+            pending.decoder.release();
+          }
+          this._removePendingEntry(cmd.id);
+          this._kittyStorage.deleteById(cmd.id);
+        }
+        break;
+      default:
+        // Unsupported selectors (c, n, p, q, r, x, y, z, f) — ignore for now
+        break;
+    }
+    return true;
+  }
+
+  private _sendResponse(id: number, message: string, quiet: number, placementId?: number): void {
+    const isOk = message === 'OK';
+    if (isOk && quiet >= 1) return;
+    if (!isOk && quiet >= 2) return;
+
+    const pPart = placementId ? `,p=${placementId}` : '';
+    const response = `\x1b_Gi=${id}${pPart};${message}\x1b\\`;
+    this._coreTerminal._core.coreService.triggerDataEvent(response);
+  }
+
+  // Image display
+
+  private _displayImage(image: IKittyImageData, cmd: IKittyCommand): Promise<boolean> {
+    return this._decodeAndDisplay(image, cmd)
+      .then(() => true)
+      .catch(() => false);
+  }
+
+  private async _decodeAndDisplay(image: IKittyImageData, cmd: IKittyCommand): Promise<void> {
+    let bitmap: ImageBitmap | undefined = await this._createBitmap(image);
+
+    try {
+      const cropX = Math.max(0, cmd.x ?? 0);
+      const cropY = Math.max(0, cmd.y ?? 0);
+      const cropW = cmd.sourceWidth || (bitmap.width - cropX);
+      const cropH = cmd.sourceHeight || (bitmap.height - cropY);
+
+      const maxCropW = Math.max(0, bitmap.width - cropX);
+      const maxCropH = Math.max(0, bitmap.height - cropY);
+      const finalCropW = Math.max(0, Math.min(cropW, maxCropW));
+      const finalCropH = Math.max(0, Math.min(cropH, maxCropH));
+
+      if (finalCropW === 0 || finalCropH === 0) {
+        throw new Error('invalid source rectangle');
+      }
+
+      if (cropX !== 0 || cropY !== 0 || finalCropW !== bitmap.width || finalCropH !== bitmap.height) {
+        const cropped = await createImageBitmap(bitmap, cropX, cropY, finalCropW, finalCropH);
+        bitmap.close();
+        bitmap = cropped;
+      }
+
+      const cw = this._renderer.dimensions?.css.cell.width || CELL_SIZE_DEFAULT.width;
+      const ch = this._renderer.dimensions?.css.cell.height || CELL_SIZE_DEFAULT.height;
+
+      // Per spec: c/r default to image's natural cell dimensions.
+      // If only one of c/r is specified, compute the other from image aspect ratio.
+      let imgCols: number;
+      let imgRows: number;
+      if (cmd.columns !== undefined && cmd.rows !== undefined) {
+        imgCols = cmd.columns;
+        imgRows = cmd.rows;
+      } else if (cmd.columns !== undefined) {
+        imgCols = cmd.columns;
+        imgRows = Math.max(1, Math.ceil((bitmap.height / bitmap.width) * (imgCols * cw) / ch));
+      } else if (cmd.rows !== undefined) {
+        imgRows = cmd.rows;
+        imgCols = Math.max(1, Math.ceil((bitmap.width / bitmap.height) * (imgRows * ch) / cw));
+      } else {
+        imgCols = Math.ceil(bitmap.width / cw);
+        imgRows = Math.ceil(bitmap.height / ch);
+      }
+
+      let w = bitmap.width;
+      let h = bitmap.height;
+
+      // Scale bitmap to fit placement rectangle when c/r are specified
+      if (cmd.columns !== undefined || cmd.rows !== undefined) {
+        w = Math.round(imgCols * cw);
+        h = Math.round(imgRows * ch);
+      }
+
+      if (w * h > this._opts.pixelLimit) {
+        throw new Error('image exceeds pixel limit');
+      }
+
+      // Save cursor position before addImage modifies it
+      const buffer = this._coreTerminal._core.buffer;
+      const savedX = buffer.x;
+      const savedY = buffer.y;
+      const savedYbase = buffer.ybase;
+
+      // Determine layer based on z-index: negative = behind text, 0+ = on top.
+      // When z<0 we always use the bottom layer even without allowTransparency —
+      // the image will simply be hidden behind the opaque text background, which
+      // is the correct behavior (client asked for "behind text").
+      const wantsBottom = cmd.zIndex !== undefined && cmd.zIndex < 0;
+      const layer: ImageLayer = wantsBottom ? 'bottom' : 'top';
+
+      if (w !== bitmap.width || h !== bitmap.height) {
+        const scaled = await createImageBitmap(bitmap, { resizeWidth: w, resizeHeight: h });
+        bitmap.close();
+        bitmap = scaled;
+      }
+
+      // Per spec: X/Y are pixel offsets within the first cell, so clamp to cell dimensions
+      const xOffset = Math.min(Math.max(0, cmd.xOffset ?? 0), cw - 1);
+      const yOffset = Math.min(Math.max(0, cmd.yOffset ?? 0), ch - 1);
+      if (xOffset !== 0 || yOffset !== 0) {
+        // Per spec: X/Y is not added to c/r area. When c/r are explicit, the
+        // total placement area remains c*cw × r*ch pixels and the offset image
+        // is clipped to fit. When c/r are unset, the padded canvas determines
+        // the natural cell dimensions.
+        const canvasW = (cmd.columns !== undefined) ? Math.round(imgCols * cw) : bitmap.width + xOffset;
+        const canvasH = (cmd.rows !== undefined) ? Math.round(imgRows * ch) : bitmap.height + yOffset;
+        const offsetCanvas = ImageRenderer.createCanvas(window.document, canvasW, canvasH);
+        const offsetCtx = offsetCanvas.getContext('2d');
+        if (!offsetCtx) {
+          throw new Error('Failed to create offset canvas context');
+        }
+        offsetCtx.drawImage(bitmap, xOffset, yOffset);
+
+        const offsetBitmap = await createImageBitmap(offsetCanvas);
+        offsetCanvas.width = offsetCanvas.height = 0;
+        bitmap.close();
+        bitmap = offsetBitmap;
+        w = bitmap.width;
+        h = bitmap.height;
+        if (w * h > this._opts.pixelLimit) {
+          throw new Error('image exceeds pixel limit');
+        }
+        if (cmd.columns === undefined) {
+          imgCols = Math.ceil(bitmap.width / cw);
+        }
+        if (cmd.rows === undefined) {
+          imgRows = Math.ceil(bitmap.height / ch);
+        }
+      }
+
+      const zIndex = cmd.zIndex ?? 0;
+      this._kittyStorage.addImage(image.id, bitmap, true, layer, zIndex);
+      bitmap = undefined;  // ownership transferred to storage
+
+      // Kitty cursor movement
+      // Per spec: cursor placed at first column after last image column,
+      // on the last row of the image. C=1 means don't move cursor.
+      if (cmd.cursorMovement === 1) {
+        // C=1: restore cursor to position before image was placed
+        const scrolled = buffer.ybase - savedYbase;
+        buffer.x = savedX;
+        // Can't restore cursor to scrollback?
+        buffer.y = Math.max(savedY - scrolled, 0);
+      } else {
+        // Default (C=0): advance cursor horizontally past the image
+        // addImage already positioned cursor on the last row via lineFeeds
+        buffer.x = Math.min(savedX + imgCols, this._coreTerminal.cols);
+      }
+    } catch (e) {
+      bitmap?.close();
+      throw e;
+    }
+  }
+
+  // Create ImageBitmap from already-decoded image data.
+  private async _createBitmap(image: IKittyImageData): Promise<ImageBitmap> {
+    let bytes: Uint8Array = new Uint8Array(await image.data.arrayBuffer());
+
+    if (image.compression === KittyCompression.ZLIB) {
+      bytes = await this._decompressZlib(bytes);
+    }
+
+    if (image.format === KittyFormat.PNG) {
+      const blob = new Blob([bytes as BlobPart], { type: 'image/png' });
+      if (!window.createImageBitmap) {
+        const url = URL.createObjectURL(blob);
+        const img = new Image();
+        return new Promise<ImageBitmap>((resolve, reject) => {
+          img.addEventListener('load', () => {
+            URL.revokeObjectURL(url);
+            const canvas = ImageRenderer.createCanvas(window.document, img.width, img.height);
+            canvas.getContext('2d')?.drawImage(img, 0, 0);
+            createImageBitmap(canvas).then(resolve).catch(reject);
+          });
+          img.addEventListener('error', () => {
+            URL.revokeObjectURL(url);
+            reject(new Error('Failed to load image'));
+          });
+          img.src = url;
+        });
+      }
+      return createImageBitmap(blob);
+    }
+
+    // Raw pixel data
+    const width = image.width;
+    const height = image.height;
+
+    if (!width || !height) {
+      throw new Error('Width and height required for raw pixel data');
+    }
+
+    const bytesPerPixel = image.format === KittyFormat.RGBA ? KittyPixelConstants.BYTES_PER_PIXEL_RGBA : KittyPixelConstants.BYTES_PER_PIXEL_RGB;
+    const expectedBytes = width * height * bytesPerPixel;
+
+    if (bytes.length < expectedBytes) {
+      throw new Error('Insufficient pixel data');
+    }
+
+    const pixelCount = width * height;
+
+    if (image.format === KittyFormat.RGBA) {
+      // RGBA: use bytes directly — no copy needed
+      return createImageBitmap(new ImageData(new Uint8ClampedArray(bytes.buffer as ArrayBuffer, bytes.byteOffset, pixelCount * KittyPixelConstants.BYTES_PER_PIXEL_RGBA), width, height));
+    }
+
+    // RGB→RGBA: interleave alpha using uint32 block processing (4 pixels per iteration).
+    // 3 uint32 reads + 4 uint32 writes per 4 pixels vs 28 byte reads/writes — ~6x faster.
+    // Assumes little-endian (all modern browsers/Node.js).
+    const data = new Uint8ClampedArray(pixelCount * KittyPixelConstants.BYTES_PER_PIXEL_RGBA);
+    const src32 = new Uint32Array(bytes.buffer, bytes.byteOffset, Math.floor(bytes.byteLength / 4));
+    const dst32 = new Uint32Array(data.buffer);
+    const alignedPixels = pixelCount & ~3;  // round down to multiple of 4
+
+    let srcOffset = 0;
+    let dstOffset = 0;
+    for (let i = 0; i < alignedPixels; i += 4) {
+      const b0 = src32[srcOffset++];
+      const b1 = src32[srcOffset++];
+      const b2 = src32[srcOffset++];
+      // Little-endian: pixel bytes are [R,G,B] → uint32 ABGR layout
+      dst32[dstOffset++] = 0xFF000000 | b0;
+      dst32[dstOffset++] = 0xFF000000 | (b0 >>> 24) | (b1 << 8);
+      dst32[dstOffset++] = 0xFF000000 | (b1 >>> 16) | (b2 << 16);
+      dst32[dstOffset++] = 0xFF000000 | (b2 >>> 8);
+    }
+
+    // Handle remaining 1–3 pixels
+    let srcByte = alignedPixels * KittyPixelConstants.BYTES_PER_PIXEL_RGB;
+    let dstByte = alignedPixels * KittyPixelConstants.BYTES_PER_PIXEL_RGBA;
+    for (let i = alignedPixels; i < pixelCount; i++) {
+      data[dstByte]     = bytes[srcByte];
+      data[dstByte + 1] = bytes[srcByte + 1];
+      data[dstByte + 2] = bytes[srcByte + 2];
+      data[dstByte + 3] = KittyPixelConstants.ALPHA_OPAQUE;
+      srcByte += KittyPixelConstants.BYTES_PER_PIXEL_RGB;
+      dstByte += KittyPixelConstants.BYTES_PER_PIXEL_RGBA;
+    }
+
+    return createImageBitmap(new ImageData(data, width, height));
+  }
+
+  private async _decompressZlib(compressed: Uint8Array): Promise<Uint8Array> {
+    try {
+      return await this._decompress(compressed, 'deflate');
+    } catch {
+      return await this._decompress(compressed, 'deflate-raw');
+    }
+  }
+
+  private async _decompress(compressed: Uint8Array, format: 'deflate' | 'deflate-raw'): Promise<Uint8Array> {
+    const ds = new DecompressionStream(format);
+    const writer = ds.writable.getWriter();
+    writer.write(compressed as BufferSource);
+    writer.close();
+
+    const chunks: Uint8Array[] = [];
+    const reader = ds.readable.getReader();
+
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+      chunks.push(value);
+    }
+
+    const totalLength = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
+    const result = new Uint8Array(totalLength);
+    let offset = 0;
+    for (const chunk of chunks) {
+      result.set(chunk, offset);
+      offset += chunk.length;
+    }
+    return result;
+  }
+
+  public get images(): ReadonlyMap<number, IKittyImageData> {
+    return this._kittyStorage.images;
+  }
+
+  public get _kittyIdToStorageId(): ReadonlyMap<number, number> {
+    return this._kittyStorage.kittyIdToStorageId;
+  }
+
+  public get pendingTransmissions(): ReadonlyMap<number, IPendingTransmission> {
+    return this._pendingTransmissions;
+  }
+}

addons/addon-image/src/kitty/KittyGraphicsTypes.test.ts

@@ -0,0 +1,149 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+import { assert } from 'chai';
+import { parseKittyCommand, KittyAction, KittyFormat } from './KittyGraphicsTypes';
+
+describe('KittyGraphicsTypes', () => {
+  describe('parseKittyCommand', () => {
+    it('should parse control data with action and format', () => {
+      const cmd = parseKittyCommand('a=T,f=100');
+      assert.strictEqual(cmd.action, 'T');
+      assert.strictEqual(cmd.format, 100);
+    });
+
+    it('should parse control data with all options', () => {
+      const cmd = parseKittyCommand('a=t,f=32,i=5,s=10,v=20,c=3,r=2,m=1,q=2');
+      assert.strictEqual(cmd.action, 't');
+      assert.strictEqual(cmd.format, 32);
+      assert.strictEqual(cmd.id, 5);
+      assert.strictEqual(cmd.width, 10);
+      assert.strictEqual(cmd.height, 20);
+      assert.strictEqual(cmd.columns, 3);
+      assert.strictEqual(cmd.rows, 2);
+      assert.strictEqual(cmd.more, 1);
+      assert.strictEqual(cmd.quiet, 2);
+    });
+
+    it('should handle empty control data', () => {
+      const cmd = parseKittyCommand('');
+      assert.strictEqual(cmd.action, undefined);
+      assert.strictEqual(cmd.format, undefined);
+    });
+
+    it('should parse transmit action', () => {
+      const cmd = parseKittyCommand('a=t,f=100');
+      assert.strictEqual(cmd.action, KittyAction.TRANSMIT);
+      assert.strictEqual(cmd.format, KittyFormat.PNG);
+    });
+
+    it('should parse delete action', () => {
+      const cmd = parseKittyCommand('a=d,i=5');
+      assert.strictEqual(cmd.action, KittyAction.DELETE);
+      assert.strictEqual(cmd.id, 5);
+    });
+
+    it('should parse empty action as empty string', () => {
+      const cmd = parseKittyCommand('a=,f=100');
+      assert.strictEqual(cmd.action, '');
+      assert.strictEqual(cmd.format, 100);
+    });
+
+    it('should leave action undefined when key is not present', () => {
+      const cmd = parseKittyCommand('f=100,i=5');
+      assert.strictEqual(cmd.action, undefined);
+      assert.strictEqual(cmd.format, 100);
+      assert.strictEqual(cmd.id, 5);
+    });
+
+    it('should parse compression key', () => {
+      const cmd = parseKittyCommand('a=t,f=32,o=z');
+      assert.strictEqual(cmd.action, 't');
+      assert.strictEqual(cmd.format, 32);
+      assert.strictEqual(cmd.compression, 'z');
+    });
+
+    it('should parse cursor movement key', () => {
+      const cmd = parseKittyCommand('a=T,f=100,C=1');
+      assert.strictEqual(cmd.cursorMovement, 1);
+    });
+
+    it('should parse cursor movement key C=0', () => {
+      const cmd = parseKittyCommand('a=T,f=100,C=0');
+      assert.strictEqual(cmd.cursorMovement, 0);
+    });
+
+    it('should parse x and y offset', () => {
+      const cmd = parseKittyCommand('a=T,x=10,y=20');
+      assert.strictEqual(cmd.x, 10);
+      assert.strictEqual(cmd.y, 20);
+    });
+
+    it('should handle keys without values', () => {
+      const cmd = parseKittyCommand('a=t,f=,i=5');
+      assert.strictEqual(cmd.action, 't');
+      assert.ok(isNaN(cmd.format!));
+      assert.strictEqual(cmd.id, 5);
+    });
+
+    it('should parse z-index key with positive value', () => {
+      const cmd = parseKittyCommand('a=T,f=100,z=10');
+      assert.strictEqual(cmd.zIndex, 10);
+    });
+
+    it('should parse z-index key with zero', () => {
+      const cmd = parseKittyCommand('a=T,f=100,z=0');
+      assert.strictEqual(cmd.zIndex, 0);
+    });
+
+    it('should parse z-index key with negative value', () => {
+      const cmd = parseKittyCommand('a=T,f=100,z=-1');
+      assert.strictEqual(cmd.zIndex, -1);
+    });
+
+    it('should leave zIndex undefined when not specified', () => {
+      const cmd = parseKittyCommand('a=T,f=100');
+      assert.strictEqual(cmd.zIndex, undefined);
+    });
+
+    it('should parse delete selector key', () => {
+      const cmd = parseKittyCommand('a=d,d=i,i=5');
+      assert.strictEqual(cmd.action, 'd');
+      assert.strictEqual(cmd.deleteSelector, 'i');
+      assert.strictEqual(cmd.id, 5);
+    });
+
+    it('should parse uppercase delete selector', () => {
+      const cmd = parseKittyCommand('a=d,d=A');
+      assert.strictEqual(cmd.deleteSelector, 'A');
+    });
+
+    it('should parse delete selector d=a (all)', () => {
+      const cmd = parseKittyCommand('a=d,d=a');
+      assert.strictEqual(cmd.deleteSelector, 'a');
+    });
+
+    it('should leave deleteSelector undefined when not specified', () => {
+      const cmd = parseKittyCommand('a=d,i=5');
+      assert.strictEqual(cmd.deleteSelector, undefined);
+    });
+
+    it('should parse placement id key', () => {
+      const cmd = parseKittyCommand('a=d,d=i,i=5,p=3');
+      assert.strictEqual(cmd.placementId, 3);
+      assert.strictEqual(cmd.deleteSelector, 'i');
+      assert.strictEqual(cmd.id, 5);
+    });
+
+    it('should leave placementId undefined when not specified', () => {
+      const cmd = parseKittyCommand('a=d,d=i,i=5');
+      assert.strictEqual(cmd.placementId, undefined);
+    });
+
+    it('should parse image number key', () => {
+      const cmd = parseKittyCommand('a=t,f=100,I=42');
+      assert.strictEqual(cmd.imageNumber, 42);
+    });
+  });
+});

addons/addon-image/src/kitty/KittyGraphicsTypes.ts

@@ -0,0 +1,195 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ *
+ * Kitty graphics protocol types, constants, and parsing utilities.
+ */
+
+import type Base64Decoder from 'xterm-wasm-parts/lib/base64/Base64Decoder.wasm';
+
+// Kitty graphics protocol action types.
+// See: https://sw.kovidgoyal.net/kitty/graphics-protocol/#control-data-reference under key 'a'.
+export const enum KittyAction {
+  TRANSMIT = 't',
+  TRANSMIT_DISPLAY = 'T',
+  QUERY = 'q',
+  PLACEMENT = 'p',
+  DELETE = 'd'
+}
+
+// Kitty graphics protocol format types.
+// See: https://sw.kovidgoyal.net/kitty/graphics-protocol/#control-data-reference
+export const enum KittyFormat {
+  RGB = 24,
+  RGBA = 32,
+  PNG = 100
+}
+
+// Kitty graphics protocol compression types.
+// See: https://sw.kovidgoyal.net/kitty/graphics-protocol/#control-data-reference under key 'o'.
+export const enum KittyCompression {
+  NONE = '',
+  ZLIB = 'z'
+}
+
+// Kitty graphics protocol control data keys.
+// See: https://sw.kovidgoyal.net/kitty/graphics-protocol/#control-data-reference
+export const enum KittyKey {
+  // Action to perform (t=transmit, T=transmit+display, q=query, p=placement, d=delete)
+  ACTION = 'a',
+  // Image format (24=RGB, 32=RGBA, 100=PNG)
+  FORMAT = 'f',
+  // Image ID for referencing stored images
+  ID = 'i',
+  // Image number (alternative to ID, terminal assigns ID)
+  IMAGE_NUMBER = 'I',
+  // Source image width in pixels
+  WIDTH = 's',
+  // Source image height in pixels
+  HEIGHT = 'v',
+  // The left edge (in pixels) of the image area to display
+  X_OFFSET = 'x',
+  // The top edge (in pixels) of the image area to display
+  Y_OFFSET = 'y',
+  // Width (in pixels) of the source rectangle to display
+  SOURCE_WIDTH = 'w',
+  // Height (in pixels) of the source rectangle to display
+  SOURCE_HEIGHT = 'h',
+  // Horizontal offset (in pixels) within the first cell
+  X_PLACEMENT_OFFSET = 'X',
+  // Vertical offset (in pixels) within the first cell
+  Y_PLACEMENT_OFFSET = 'Y',
+  // Number of terminal columns to display the image over
+  COLUMNS = 'c',
+  // Number of terminal rows to display the image over
+  ROWS = 'r',
+  // More data flag (1=more chunks coming, 0=final chunk)
+  MORE = 'm',
+  // Compression type (z=zlib). This is essential for chunking larger images.
+  COMPRESSION = 'o',
+  // Quiet mode (1=suppress OK responses, 2=suppress error responses)
+  QUIET = 'q',
+  // Cursor movement policy (0=move cursor after image, 1=don't move cursor)
+  CURSOR_MOVEMENT = 'C',
+  // Z-index for image layering (negative = behind text, 0+ = on top)
+  Z_INDEX = 'z',
+  // Transmission medium (d=direct, f=file, t=temp file, s=shared memory)
+  TRANSMISSION = 't',
+  // Delete selector (a/A=all, i/I=by id, c/C=at cursor, etc.) — only used when a=d
+  DELETE_SELECTOR = 'd',
+  // Placement ID for targeting specific placements
+  PLACEMENT_ID = 'p'
+}
+
+// Pixel format constants
+export const enum KittyPixelConstants {
+  BYTES_PER_PIXEL_RGB = 3,
+  BYTES_PER_PIXEL_RGBA = 4,
+  ALPHA_OPAQUE = 255
+}
+
+// Parsed Kitty graphics command.
+export interface IKittyCommand {
+  action?: string;
+  format?: number;
+  id?: number;
+  imageNumber?: number;
+  width?: number;
+  height?: number;
+  x?: number;
+  y?: number;
+  sourceWidth?: number;
+  sourceHeight?: number;
+  xOffset?: number;
+  yOffset?: number;
+  columns?: number;
+  rows?: number;
+  more?: number;
+  quiet?: number;
+  cursorMovement?: number;
+  zIndex?: number;
+  transmission?: string;
+  deleteSelector?: string;
+  placementId?: number;
+  compression?: string;
+  payload?: string;
+}
+
+// Pending chunked transmission state.
+// Stores metadata from the first chunk while accumulating decoded payload data.
+export interface IPendingTransmission {
+  // The parsed command from the first chunk (contains action, format, dimensions, etc.)
+  cmd: IKittyCommand;
+  // Decoder used across chunked payloads
+  decoder: Base64Decoder;
+  // Total encoded (base64) bytes received across all chunks - for size limit enforcement
+  totalEncodedSize: number;
+  // Whether any chunk has failed to decode
+  decodeError: boolean;
+}
+
+// Stored Kitty image data.
+export interface IKittyImageData {
+  id: number;
+  // Decoded image data stored as Blob (off JS heap) to avoid 2GB heap limit
+  data: Blob;
+  width: number;
+  height: number;
+  format: 24 | 32 | 100;
+  compression?: string;
+}
+
+// Parses Kitty graphics control data into a command object.
+export function parseKittyCommand(data: string): IKittyCommand {
+  const cmd: IKittyCommand = {};
+  const parts = data.split(',');
+
+  for (const part of parts) {
+    const eqIdx = part.indexOf('=');
+    if (eqIdx === -1) continue;
+
+    const key = part.substring(0, eqIdx);
+    const value = part.substring(eqIdx + 1);
+
+    // Handle string keys first
+    if (key === KittyKey.ACTION) {
+      cmd.action = value;
+      continue;
+    }
+    if (key === KittyKey.COMPRESSION) {
+      cmd.compression = value;
+      continue;
+    }
+    if (key === KittyKey.TRANSMISSION) {
+      cmd.transmission = value;
+      continue;
+    }
+    if (key === KittyKey.DELETE_SELECTOR) {
+      cmd.deleteSelector = value;
+      continue;
+    }
+    const numValue = parseInt(value);
+    switch (key) {
+      case KittyKey.FORMAT: cmd.format = numValue; break;
+      case KittyKey.ID: cmd.id = numValue; break;
+      case KittyKey.IMAGE_NUMBER: cmd.imageNumber = numValue; break;
+      case KittyKey.WIDTH: cmd.width = numValue; break;
+      case KittyKey.HEIGHT: cmd.height = numValue; break;
+      case KittyKey.X_OFFSET: cmd.x = numValue; break;
+      case KittyKey.Y_OFFSET: cmd.y = numValue; break;
+      case KittyKey.SOURCE_WIDTH: cmd.sourceWidth = numValue; break;
+      case KittyKey.SOURCE_HEIGHT: cmd.sourceHeight = numValue; break;
+      case KittyKey.X_PLACEMENT_OFFSET: cmd.xOffset = numValue; break;
+      case KittyKey.Y_PLACEMENT_OFFSET: cmd.yOffset = numValue; break;
+      case KittyKey.COLUMNS: cmd.columns = numValue; break;
+      case KittyKey.ROWS: cmd.rows = numValue; break;
+      case KittyKey.MORE: cmd.more = numValue; break;
+      case KittyKey.QUIET: cmd.quiet = numValue; break;
+      case KittyKey.CURSOR_MOVEMENT: cmd.cursorMovement = numValue; break;
+      case KittyKey.Z_INDEX: cmd.zIndex = numValue; break;
+      case KittyKey.PLACEMENT_ID: cmd.placementId = numValue; break;
+    }
+  }
+
+  return cmd;
+}

addons/addon-image/src/kitty/KittyImageStorage.ts

@@ -0,0 +1,155 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { IDisposable } from '@xterm/xterm';
+import { ImageStorage } from '../ImageStorage';
+import { ImageLayer, IAddImageOpts } from '../Types';
+import { IKittyImageData } from './KittyGraphicsTypes';
+
+// Kitty-specific image storage controller.
+//
+// Wraps shared ImageStorage with kitty protocol semantics:
+// - tracks transmitted image payloads by kitty image id
+// - tracks kitty image id -> shared ImageStorage id mapping for displayed images
+// - mirrors shared-storage evictions into kitty maps
+// - applies protocol-level undisplayed-image eviction policy
+export class KittyImageStorage implements IDisposable {
+  private static readonly _maxStoredImages = 256;
+
+  private _nextImageId = 1;
+  private readonly _images: Map<number, IKittyImageData> = new Map();
+  // TODO: Support multiple placements per image. The kitty spec identifies
+  // placements by an (image id, placement id) pair — same i + different p
+  // values should coexist, and same i + same p should replace the prior
+  // placement. Currently we track only one storage entry per kitty image id,
+  // so multiple placements of the same image overwrite each other. Fixing
+  // this requires changing these maps to Map<number, Map<number, number>>
+  // (kittyId → placementId → storageId) and updating addImage/deleteById
+  // accordingly. The underlying shared ImageStorage would also need to
+  // support multiple entries per logical image.
+  private readonly _kittyIdToStorageId: Map<number, number> = new Map();
+  private readonly _storageIdToKittyId: Map<number, number> = new Map();
+
+  private readonly _previousOnImageDeleted: ((storageId: number) => void) | undefined;
+  private readonly _wrappedOnImageDeleted: (storageId: number) => void;
+  private readonly _handleStorageImageDeleted = (storageId: number): void => {
+    const kittyId = this._storageIdToKittyId.get(storageId);
+    if (kittyId !== undefined) {
+      this._kittyIdToStorageId.delete(kittyId);
+      this._storageIdToKittyId.delete(storageId);
+      this._images.delete(kittyId);
+    }
+  };
+  private _addImageOpts: IAddImageOpts = { scrolling: true, layer: 'top', zIndex: 0, cursorPos: 'iip' };
+
+  constructor(
+    private readonly _storage: ImageStorage
+  ) {
+    this._previousOnImageDeleted = this._storage.onImageDeleted;
+    this._wrappedOnImageDeleted = (storageId: number) => {
+      this._previousOnImageDeleted?.(storageId);
+      this._handleStorageImageDeleted(storageId);
+    };
+    this._storage.onImageDeleted = this._wrappedOnImageDeleted;
+  }
+
+  public reset(): void {
+    this._nextImageId = 1;
+    this._images.clear();
+    this._kittyIdToStorageId.clear();
+    this._storageIdToKittyId.clear();
+  }
+
+  public dispose(): void {
+    this.reset();
+    if (this._storage.onImageDeleted === this._wrappedOnImageDeleted) {
+      this._storage.onImageDeleted = this._previousOnImageDeleted;
+    }
+  }
+
+  public storeImage(id: number | undefined, imageData: Omit<IKittyImageData, 'id'>): number {
+    const imageId = id ?? this._nextImageId++;
+
+    const oldStorageId = this._kittyIdToStorageId.get(imageId);
+    if (oldStorageId !== undefined) {
+      this._storage.deleteImage(oldStorageId);
+      this._kittyIdToStorageId.delete(imageId);
+      this._storageIdToKittyId.delete(oldStorageId);
+    }
+
+    if (!this._images.has(imageId) && this._images.size >= KittyImageStorage._maxStoredImages) {
+      this._evictUndisplayedImages();
+    }
+
+    this._images.set(imageId, {
+      ...imageData,
+      id: imageId
+    });
+    return imageId;
+  }
+
+  public addImage(kittyId: number, image: HTMLCanvasElement | ImageBitmap, scrolling: boolean, layer: ImageLayer, zIndex: number): void {
+    // Clean up stale reverse-mapping from a previous placement of the same
+    // kitty image.  The old shared-storage entry is kept (it may still be
+    // visible on screen) but its reverse mapping is removed so that eviction
+    // of the old entry won't incorrectly delete the kitty image data.
+    const oldStorageId = this._kittyIdToStorageId.get(kittyId);
+    if (oldStorageId !== undefined) {
+      this._storageIdToKittyId.delete(oldStorageId);
+    }
+    this._addImageOpts.scrolling = scrolling;
+    this._addImageOpts.layer = layer;
+    this._addImageOpts.zIndex = zIndex;
+    const storageId = this._storage.addImage(image, this._addImageOpts);
+    this._kittyIdToStorageId.set(kittyId, storageId);
+    this._storageIdToKittyId.set(storageId, kittyId);
+  }
+
+  public getImage(kittyId: number): IKittyImageData | undefined {
+    return this._images.get(kittyId);
+  }
+
+  public deleteById(kittyId: number): void {
+    this._images.delete(kittyId);
+    const storageId = this._kittyIdToStorageId.get(kittyId);
+    if (storageId !== undefined) {
+      this._storage.deleteImage(storageId);
+      this._kittyIdToStorageId.delete(kittyId);
+      this._storageIdToKittyId.delete(storageId);
+    }
+  }
+
+  public deleteAll(): void {
+    this._images.clear();
+    for (const storageId of this._kittyIdToStorageId.values()) {
+      this._storage.deleteImage(storageId);
+    }
+    this._kittyIdToStorageId.clear();
+    this._storageIdToKittyId.clear();
+  }
+
+  public get images(): ReadonlyMap<number, IKittyImageData> {
+    return this._images;
+  }
+
+  public get kittyIdToStorageId(): ReadonlyMap<number, number> {
+    return this._kittyIdToStorageId;
+  }
+
+  public get lastImageId(): number {
+    return this._nextImageId - 1;
+  }
+
+  private _evictUndisplayedImages(): void {
+    for (const [kittyId] of this._images) {
+      if (this._images.size <= KittyImageStorage._maxStoredImages / 2) {
+        break;
+      }
+      if (!this._kittyIdToStorageId.has(kittyId)) {
+        this._images.delete(kittyId);
+      }
+    }
+  }
+}

addons/addon-image/src/tsconfig.json

@@ -11,11 +11,11 @@
     "types": [
       "../../../node_modules/@types/mocha"
     ],
-    "baseUrl": ".",
     "paths": {
       "browser/*": [ "../../../src/browser/*" ],
       "common/*": [ "../../../src/common/*" ],
-      "@xterm/addon-image": [ "../typings/addon-image.d.ts" ]
+      "@xterm/addon-image": [ "../typings/addon-image.d.ts" ],
+      "*": [ "./*" ]
     }
   },
   "include": [

addons/addon-image/test/ImageAddon.test.ts

@@ -8,6 +8,7 @@ import { readFileSync } from 'fs';
 import { FINALIZER, introducer, sixelEncode } from 'sixel';
 import { ITestContext, createTestContext, openTerminal, pollFor, timeout } from '../../../test/playwright/TestUtils';
 import { deepStrictEqual, ok, strictEqual } from 'assert';
+import QoiEncoder from 'xterm-wasm-parts/lib/qoi/QoiEncoder.wasm';
 
 /**
  * Plugin ctor options.
@@ -23,6 +24,8 @@ export interface IImageAddonOptions {
   sixelSizeLimit: number;
   iipSupport: boolean;
   iipSizeLimit: number;
+  kittySupport: boolean;
+  kittySizeLimit: number;
 }
 
 // eslint-disable-next-line
@@ -72,6 +75,10 @@ const TESTDATA_IIP: [string, [number, number]][] = [
   [readFileSync('./addons/addon-image/fixture/iip/w3c_jpg.iip', { encoding: 'utf-8' }), [72, 48]],
   [readFileSync('./addons/addon-image/fixture/iip/w3c_png.iip', { encoding: 'utf-8' }), [72, 48]]
 ];
+const PALETTE_PNG_BASE64 = readFileSync('./addons/addon-image/fixture/palette.png').toString('base64');
+const qoiEnc = new QoiEncoder(1024*1024);
+const qoiData = qoiEnc.encode(TESTDATA.bytes, 640, 80);
+const PALETTE_QOI_BASE64 = Buffer.from(qoiData).toString('base64');
 
 let ctx: ITestContext;
 test.beforeAll(async ({ browser }) => {
@@ -83,11 +90,6 @@ test.afterAll(async () => await ctx.page.close());
 test.describe('ImageAddon', () => {
 
   test.beforeEach(async ({}, testInfo) => {
-    // DEBT: This test never worked on webkit
-    if (ctx.browser.browserType().name() === 'webkit') {
-      testInfo.skip();
-      return;
-    }
     await ctx.page.evaluate(`
       window.term.reset()
       window.imageAddon?.dispose();
@@ -130,11 +132,13 @@ test.describe('ImageAddon', () => {
         sixelSupport: true,
         sixelScrolling: true,
         sixelPaletteLimit: 512,  // set to 512 to get example image working
-        sixelSizeLimit: 25000000,
+        sixelSizeLimit: 33554432,
         storageLimit: 128,
         showPlaceholder: true,
         iipSupport: true,
-        iipSizeLimit: 20000000
+        iipSizeLimit: 33554432,
+        kittySupport: true,
+        kittySizeLimit: 33554432
       };
       deepStrictEqual(await ctx.page.evaluate(`window.imageAddon._opts`), DEFAULT_OPTIONS);
     });
@@ -149,7 +153,9 @@ test.describe('ImageAddon', () => {
         storageLimit: 10,
         showPlaceholder: false,
         iipSupport: false,
-        iipSizeLimit: 1000
+        iipSizeLimit: 1000,
+        kittySupport: false,
+        kittySizeLimit: 1000
       };
       await ctx.page.evaluate(opts => {
         (window as any).imageAddonCustom = new ImageAddon(opts.opts);
@@ -190,6 +196,18 @@ test.describe('ImageAddon', () => {
   });
 
   test.describe('image lifecycle & eviction', () => {
+    test('onImageAdded fires for each image', async () => {
+      await ctx.page.evaluate(`
+        window._imageAddedCount = 0;
+        window.imageAddon.onImageAdded(() => { window._imageAddedCount++; });
+      `);
+      await ctx.proxy.write(SIXEL_SEQ_0);
+      await pollFor(ctx.page, 'window._imageAddedCount', 1);
+      await ctx.proxy.write(SIXEL_SEQ_0);
+      await pollFor(ctx.page, 'window._imageAddedCount', 2);
+      await ctx.proxy.write(SIXEL_SEQ_0);
+      await pollFor(ctx.page, 'window._imageAddedCount', 3);
+    });
     test('delete image once scrolled off', async () => {
       await ctx.proxy.write(SIXEL_SEQ_0);
       pollFor(ctx.page, 'window.imageAddon._storage._images.size', 1);
@@ -272,6 +290,67 @@ test.describe('ImageAddon', () => {
     });
   });
 
+  test.describe('IIP support', () => {
+    test('size params is optional/informative', async () => {
+      // too small size param
+      await ctx.proxy.write(`\x1b]1337;File=inline=1;size=5:${PALETTE_PNG_BASE64}\x07`);
+      deepStrictEqual(await getOrigSize(1), [640, 80]);
+      // no size aparm at all
+      await ctx.proxy.write(`\x1b[10H\x1b]1337;File=inline=1:${PALETTE_QOI_BASE64}\x07`);
+      deepStrictEqual(await getOrigSize(2), [640, 80]);
+    });
+    test.skip('FilePart support - bytewise', async () => {
+      // opener
+      await ctx.proxy.write(`\x1b]1337;MultipartFile=inline=1\x07`);
+      // byte-wise
+      for (let i = 0; i < PALETTE_PNG_BASE64.length; ++i) {
+        await ctx.proxy.write(`\x1b]1337;FilePart=${PALETTE_PNG_BASE64[i]}\x07`);
+      }
+      // finalizer
+      await ctx.proxy.write(`\x1b]1337;FileEnd\x07`);
+      deepStrictEqual(await getOrigSize(1), [640, 80]);
+    });
+    test('FilePart support - chunks', async () => {
+      // opener
+      await ctx.proxy.write(`\x1b]1337;MultipartFile=inline=1\x07`);
+      // chunks
+      for (let i = 0; i < PALETTE_PNG_BASE64.length; i += 256) {
+        await ctx.proxy.write(`\x1b]1337;FilePart=${PALETTE_PNG_BASE64.slice(i, i + 256)}\x07`);
+      }
+      // finalizer
+      await ctx.proxy.write(`\x1b]1337;FileEnd\x07`);
+      deepStrictEqual(await getOrigSize(1), [640, 80]);
+    });
+    test('FilePart support - edgecases', async () => {
+      // multiple opener do not harm
+      for (let i = 0; i < 10; ++i) {
+        await ctx.proxy.write(`\x1b]1337;MultipartFile=inline=1\x07`);
+      }
+      // multiple finalizer do not harm
+      for (let i = 0; i < 5; ++i) {
+        await ctx.proxy.write(`\x1b]1337;FileEnd\x07`);
+      }
+      // chunks w'o opener are ignored
+      for (let i = 0; i < PALETTE_PNG_BASE64.length; i += 256) {
+        await ctx.proxy.write(`\x1b]1337;FilePart=${PALETTE_PNG_BASE64.slice(i, i + 256)}\x07`);
+      }
+      await ctx.proxy.write(`\x1b]1337;FileEnd\x07`);
+      pollFor(ctx.page, 'window.imageAddon._storage._images.size', 0);
+    });
+    test('FilePart support - other IIP sequence cancels chunked image', async () => {
+      // opener
+      await ctx.proxy.write(`\x1b]1337;MultipartFile=inline=1\x07`);
+      // chunks
+      for (let i = 0; i < PALETTE_PNG_BASE64.length; i += 256) {
+        await ctx.proxy.write(`\x1b]1337;FilePart=${PALETTE_PNG_BASE64.slice(i, i + 256)}\x07`);
+      }
+      // finalizer skipped
+      // write spinfox.png
+      await ctx.proxy.write(TESTDATA_IIP[1][0]);
+      deepStrictEqual(await getOrigSize(1), TESTDATA_IIP[1][1]);
+    });
+  });
+
   test.describe('IIP support - testimages', () => {
     test('palette.png', async () => {
       await ctx.proxy.write(TESTDATA_IIP[0][0]);
@@ -294,6 +373,68 @@ test.describe('ImageAddon', () => {
       deepStrictEqual(await getOrigSize(1), TESTDATA_IIP[4][1]);
     });
   });
+
+  test.describe('IIP - QOI support', () => {
+    test('palette should yield same bytes from PNG and QOI', async () => {
+      await ctx.proxy.write(`\x1b]1337;File=inline=1;size=525:${PALETTE_PNG_BASE64}\x07`);
+      deepStrictEqual(await getOrigSize(1), [640, 80]);
+      await ctx.proxy.write(`\x1b[10H\x1b]1337;File=inline=1;size=${qoiData.length}:${PALETTE_QOI_BASE64}\x07`);
+      deepStrictEqual(await getOrigSize(2), [640, 80]);
+      const pngScrape = await getImageAtBufferCell(0, 0);
+      const qoiScrape = await getImageAtBufferCell(0, 11);
+      deepStrictEqual(qoiScrape, pngScrape);
+    });
+  });
+
+  test.describe('IIP - resizing', () => {
+    /**
+     * The correct resize behavior is wonky and needs to be tested against iTerm2,
+     * especially for missing params to derive correct default behavior.
+     * We document the current behavior here w'o claiming to be fully in line with iTerm2.
+     * ref: https://iterm2.com/documentation-images.html
+     * imgcat: https://iterm2.com/utilities/imgcat
+     *
+     * NOTE: QOI has a slightly different parse path, thus we test resizing explicitly
+     */
+    const images = [
+      ['palette.png', 525, PALETTE_PNG_BASE64],
+      ['palette.qoi', qoiData.length, PALETTE_QOI_BASE64]
+    ];
+    for (const [name, size, payload] of images) {
+      test(name + ': N --> width=20 height=5 preserveAspectRatio=0', async () => {
+        // cell based resize
+        const header = 'width=20;height=5;preserveAspectRatio=0';
+        await ctx.proxy.write(`\x1b]1337;File=inline=1;size=${size};${header}:${payload}\x07`);
+        const dim = await getDimensions();
+        deepStrictEqual(await getOrigSize(1), [dim.cellWidth * 20, dim.cellHeight * 5]);
+      });
+      test(name + ': Npx --> width=320px height=160px preserveAspectRatio=0', async () => {
+        // pixel based resize
+        const header = 'width=320px;height=160px;preserveAspectRatio=0';
+        await ctx.proxy.write(`\x1b]1337;File=inline=1;size=${size};${header}:${payload}\x07`);
+        deepStrictEqual(await getOrigSize(1), [320, 160]);
+      });
+      test(name + ': N% --> width=50% height=30% preserveAspectRatio=0', async () => {
+        // % of viewport resize
+        const header = 'width=50%;height=30%;preserveAspectRatio=0';
+        await ctx.proxy.write(`\x1b]1337;File=inline=1;size=${size};${header}:${payload}\x07`);
+        const dim = await getDimensions();
+        deepStrictEqual(await getOrigSize(1), [Math.floor(dim.width * 0.5), Math.floor(dim.height * 0.3)]);
+      });
+      test(name + ': ommitted dimension assumes preserveAspectRatio=1', async () => {
+        // width provided in percent
+        const header = 'width=50%';
+        await ctx.proxy.write(`\x1b]1337;File=inline=1;size=${size};${header}:${payload}\x07`);
+        const dim = await getDimensions();
+        const width = Math.floor(dim.width * 0.5);
+        deepStrictEqual(await getOrigSize(1), [width, Math.floor(width * 80 / 640)]);
+        // height provided in pixel
+        const header2 = 'height=200px';
+        await ctx.proxy.write(`\x1b]1337;File=inline=1;size=${size};${header2}:${payload}\x07`);
+        deepStrictEqual(await getOrigSize(2), [Math.floor(200 * 640 / 80), 200]);
+      });
+    }
+  });
 });
 
 /**
@@ -327,3 +468,7 @@ async function getOrigSize(id: number): Promise<[number, number]> {
     window.imageAddon._storage._images.get(${id}).orig.height
   ]`);
 }
+
+async function getImageAtBufferCell(x: number, y: number): Promise<string | undefined> {
+  return ctx.page.evaluate<any>(`window.imageAddon.getImageAtBufferCell(${x}, ${y})?.toDataURL('image/png')`);
+}

addons/addon-image/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-image/typings/addon-image.d.ts

@@ -3,7 +3,7 @@
  * @license MIT
  */
 
-import { Terminal, ITerminalAddon } from '@xterm/xterm';
+import { Terminal, ITerminalAddon, IEvent } from '@xterm/xterm';
 
 declare module '@xterm/addon-image' {
   export interface IImageAddonOptions {
@@ -76,6 +76,15 @@ declare module '@xterm/addon-image' {
     iipSupport?: boolean;
     /** IIP sequence size limit (default 20000000 bytes). */
     iipSizeLimit?: number;
+
+    /**
+     * Kitty graphics protocol settings
+     */
+
+    /** Whether Kitty graphics protocol is enabled (default is true). */
+    kittySupport?: boolean;
+    /** Kitty image size limit in bytes (default 20000000 bytes). */
+    kittySizeLimit?: number;
   }
 
   export class ImageAddon implements ITerminalAddon {
@@ -107,6 +116,11 @@ declare module '@xterm/addon-image' {
      */
     public showPlaceholder: boolean;
 
+    /**
+     * Event fired whenever a new image is added to storage.
+     */
+    public readonly onImageAdded: IEvent<void>;
+
     /**
      * Get original image canvas at buffer position.
      */

addons/addon-ligatures/package.json

@@ -14,13 +14,13 @@
     "node": ">8.0.0"
   },
   "scripts": {
-    "build": "tsc -p src",
-    "watch": "tsc -w -p src",
+    "build": "tsgo -p src",
+    "watch": "tsgo -w -p src",
     "prepackage": "npm run build",
     "package": "webpack",
     "pretest": "npm run build",
     "test": "nyc mocha out/**/*.test.js",
-    "prepublish": "npm run package"
+    "prepublishOnly": "npm run package"
   },
   "keywords": [
     "font",
@@ -31,15 +31,11 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "lru-cache": "^6.0.0",
-    "opentype.js": "^0.8.0"
+    "lru-cache": "^11.3.6",
+    "opentype.js": "^2.0.0"
   },
   "devDependencies": {
-    "@types/lru-cache": "^5.1.0",
-    "@types/opentype.js": "^0.7.0",
-    "axios": "^1.6.0",
-    "font-finder": "^1.1.0",
-    "mkdirp": "0.5.5",
-    "yauzl": "^2.10.0"
+    "@types/opentype.js": "^1.3.9",
+    "font-finder": "^1.1.0"
   }
 }

addons/addon-ligatures/src/fontLigatures/index.ts

@@ -1,5 +1,5 @@
 import * as opentype from 'opentype.js';
-import LRUCache = require('lru-cache');
+import { LRUCache } from 'lru-cache';
 
 import { IFont, ILigatureData, IFlattenedLookupTree, ILookupTree, IOptions } from './types';
 import mergeTrees from './merge';
@@ -23,8 +23,8 @@ class FontImpl implements IFont {
 
     if (options.cacheSize > 0) {
       this._cache = new LRUCache({
-        max: options.cacheSize,
-        length: ((val: ILigatureData | [number, number][], key: string) => key.length) as any
+        maxSize: options.cacheSize,
+        sizeCalculation: ((val: ILigatureData | [number, number][], key: string) => key.length) as any
       });
     }
 

addons/addon-ligatures/src/fontLigatures/mergeRange.ts

@@ -44,7 +44,6 @@ export default function mergeRange(ranges: [number, number][], newRangeStart: nu
         // current range
         ranges[i - 1][1] = Math.max(newRangeEnd, range[1]);
         ranges.splice(i, 1);
-        inRange = false;
         return ranges;
       }
       // Case 7: New range extends from previous range past the

addons/addon-ligatures/test/tsconfig.json

@@ -9,8 +9,12 @@
     "outDir": "../out-esbuild-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "strict": true,
+    "paths": {
+      "*": [
+        "./*"
+      ]
+    },
     "types": [
       "../../../node_modules/@types/mocha",
       "../../../node_modules/@types/node"

addons/addon-progress/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-progress/test/ProgressAddon.test.ts

@@ -9,15 +9,18 @@ import { ITestContext, createTestContext, openTerminal } from '../../../test/pla
 
 
 let ctx: ITestContext;
-test.beforeAll(async ({ browser }) => {
-  ctx = await createTestContext(browser);
-  ctx.page.setViewportSize({ width: 1024, height: 768 });
-  await openTerminal(ctx);
-});
-test.afterAll(async () => await ctx.page.close());
-
 
 test.describe('ProgressAddon', () => {
+  test.describe.configure({ mode: 'serial' });
+
+  test.beforeAll(async ({ browser }) => {
+    ctx = await createTestContext(browser);
+    await openTerminal(ctx);
+  });
+  test.afterAll(async () => {
+    await ctx?.page?.close();
+  });
+
   test.beforeEach(async function(): Promise<any> {
     await ctx.page.evaluate(`
       window.progressStack = [];

addons/addon-progress/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-search/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "prepackage": "../../node_modules/.bin/tsc -p .",
+    "prepackage": "../../node_modules/.bin/tsgo -p .",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",
     "start": "node ../../demo/start"

addons/addon-search/src/SearchEngine.ts

@@ -174,7 +174,7 @@ export class SearchEngine {
     this._terminal.clearSelection();
 
     let startRow = this._terminal.buffer.active.baseY + this._terminal.rows - 1;
-    let startCol = this._terminal.cols;
+    const startCol = this._terminal.cols;
     const isReverseSearch = true;
 
     this._lineCache.initLinesCache();
@@ -186,14 +186,14 @@ export class SearchEngine {
     let result: ISearchResult | undefined;
     if (prevSelectedPos) {
       searchPosition.startRow = startRow = prevSelectedPos.start.y;
-      searchPosition.startCol = startCol = prevSelectedPos.start.x;
+      searchPosition.startCol = prevSelectedPos.start.x;
       if (cachedSearchTerm !== term) {
         // Try to expand selection to right first.
         result = this._findInLine(term, searchPosition, searchOptions, false);
         if (!result) {
           // If selection was not able to be expanded to the right, then try reverse search
           searchPosition.startRow = startRow = prevSelectedPos.end.y;
-          searchPosition.startCol = startCol = prevSelectedPos.end.x;
+          searchPosition.startCol = prevSelectedPos.end.x;
         }
       }
     }

addons/addon-search/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-serialize/benchmark/tsconfig.json

@@ -4,13 +4,13 @@
       "dom",
       "es2021"
     ],
+    "rootDir": "..",
     "outDir": "../out-benchmark",
     "types": ["../../../node_modules/@types/node"],
-    "moduleResolution": "node",
+    "moduleResolution": "nodenext",
     "strict": false,
     "target": "es2021",
-    "module": "commonjs",
-    "baseUrl": ".",
+    "module": "nodenext",
     "paths": {
       "common/*": ["../../../src/common/*"],
       "browser/*": ["../../../src/browser/*"],

addons/addon-serialize/package.json

@@ -16,13 +16,13 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",
     "start": "node ../../demo/start",
-    "benchmark": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json",
-    "benchmark-baseline": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --baseline out-benchmark/benchmark/*benchmark.js",
-    "benchmark-eval": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --eval out-benchmark/benchmark/*benchmark.js"
+    "benchmark": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json",
+    "benchmark-baseline": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --baseline out-benchmark/benchmark/*benchmark.js",
+    "benchmark-eval": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --eval out-benchmark/benchmark/*benchmark.js"
   }
 }

addons/addon-serialize/src/tsconfig.json

@@ -10,7 +10,6 @@
     "outDir": "../out",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
@@ -23,6 +22,7 @@
       ]
     },
     "strict": true,
+    "skipLibCheck": true,
     "types": [
       "../../../node_modules/@types/mocha"
     ]

addons/addon-serialize/test/SerializeAddon.test.ts

@@ -49,7 +49,14 @@ test.describe('SerializeAddon', () => {
         for (let i = 0; i < buffer.length; i++) {
           // Do this intentionally to get content of underlining source
           const bufferLine = buffer.getLine(i)._line;
-          lines.push(JSON.stringify(bufferLine));
+          lines.push(JSON.stringify(bufferLine, (key, value) => {
+            // BufferLine caches are internal/transient and can legitimately differ
+            // across equivalent terminal states.
+            if (key === '_stringCache' || key === '_stringCacheEntryRef') {
+              return undefined;
+            }
+            return value;
+          }));
         }
         return {
           x: buffer.cursorX,

addons/addon-serialize/test/tsconfig.json

@@ -9,7 +9,6 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"

addons/addon-unicode-graphemes/benchmark/tsconfig.json

@@ -1,13 +1,13 @@
 {
   "compilerOptions": {
     "lib": ["dom", "es6"],
+    "rootDir": "..",
     "outDir": "../out-benchmark",
     "types": ["../../../node_modules/@types/node"],
-    "moduleResolution": "node",
+    "moduleResolution": "nodenext",
     "strict": false,
     "target": "es2015",
-    "module": "commonjs",
-    "baseUrl": ".",
+    "module": "nodenext",
     "paths": {
       "common/*": ["../../../src/common/*"],
       "browser/*": ["../../../src/browser/*"],

addons/addon-unicode-graphemes/package.json

@@ -16,13 +16,13 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",
     "start": "node ../../demo/start",
-    "benchmark": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json out-benchmark/benchmark/*benchmark.js",
-    "benchmark-baseline": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --baseline out-benchmark/benchmark/*benchmark.js",
-    "benchmark-eval": "NODE_PATH=../../out:./out:./out-benchmark/ ../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --eval out-benchmark/benchmark/*benchmark.js"
+    "benchmark": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json out-benchmark/benchmark/*benchmark.js",
+    "benchmark-baseline": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --baseline out-benchmark/benchmark/*benchmark.js",
+    "benchmark-eval": "../../node_modules/.bin/xterm-benchmark -r 5 -c benchmark/benchmark.json --eval out-benchmark/benchmark/*benchmark.js"
   }
 }

addons/addon-unicode-graphemes/src/tsconfig.json

@@ -11,7 +11,6 @@
     "sourceMap": true,
     "removeComments": true,
     "strict": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"

addons/addon-unicode-graphemes/test/tsconfig.json

@@ -9,7 +9,6 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"

addons/addon-unicode11/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-unicode11/src/tsconfig.json

@@ -11,13 +11,15 @@
     "sourceMap": true,
     "removeComments": true,
     "strict": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "@xterm/addon-unicode11": [
         "../typings/addon-unicode11.d.ts"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "types": [

addons/addon-unicode11/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-web-fonts/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-web-fonts/test/WebFontsAddon.test.ts

@@ -33,16 +33,16 @@ test.describe('WebFontsAddon', () => {
   test.describe('font loading at runtime', () => {
     test('loadFonts (JS)', async () => {
       await ctx.page.evaluate(`
-        const ff1 = new FontFace('Kongtext', "url(/kongtext.regular.ttf) format('truetype')");
-        const ff2 = new FontFace('BPdots', "url(/bpdots.regular.otf) format('opentype')");
+        const ff1 = new FontFace('Kongtext', "url(/fonts/kongtext.regular.ttf) format('truetype')");
+        const ff2 = new FontFace('BPdots', "url(/fonts/bpdots.regular.otf) format('opentype')");
         loadFonts([ff1, ff2]);
       `);
       deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'loaded' }, { family: 'BPdots', status: 'loaded' }]);
     });
     test('loadFonts (CSS, unquoted)', async () => {
       await ctx.page.evaluate(`
-        document.styleSheets[0].insertRule("@font-face {font-family: Kongtext; src: url(/kongtext.regular.ttf) format('truetype')}", 0);
-        document.styleSheets[0].insertRule("@font-face {font-family: BPdots; src: url(/bpdots.regular.otf) format('opentype')}", 1);
+        document.styleSheets[0].insertRule("@font-face {font-family: Kongtext; src: url(/fonts/kongtext.regular.ttf) format('truetype')}", 0);
+        document.styleSheets[0].insertRule("@font-face {font-family: BPdots; src: url(/fonts/bpdots.regular.otf) format('opentype')}", 1);
         loadFonts(['Kongtext', 'BPdots']);
       `);
       deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'loaded' }, { family: 'BPdots', status: 'loaded' }]);
@@ -50,8 +50,8 @@ test.describe('WebFontsAddon', () => {
     test('loadFonts (CSS, quoted)', async ({ browser }) => {
       // NOTE: firefox preserves family quotes from CSS rules in fontface, all other browsers unquote them
       await ctx.page.evaluate(`
-        document.styleSheets[0].insertRule("@font-face {font-family: 'Kongtext'; src: url(/kongtext.regular.ttf) format('truetype')}", 0);
-        document.styleSheets[0].insertRule("@font-face {font-family: 'BPdots'; src: url(/bpdots.regular.otf) format('opentype')}", 1);
+        document.styleSheets[0].insertRule("@font-face {font-family: 'Kongtext'; src: url(/fonts/kongtext.regular.ttf) format('truetype')}", 0);
+        document.styleSheets[0].insertRule("@font-face {font-family: 'BPdots'; src: url(/fonts/bpdots.regular.otf) format('opentype')}", 1);
         loadFonts(['Kongtext', 'BPdots']);
       `);
       if (browser.browserType().name() === 'firefox') {
@@ -63,8 +63,8 @@ test.describe('WebFontsAddon', () => {
     test('FontFace hashing', async () => {
       // multiple calls of `loadFonts` with the same objects shall not bloat document.fonts
       await ctx.page.evaluate(`
-        const ff1 = new FontFace('Kongtext', "url(/kongtext.regular.ttf) format('truetype')");
-        const ff2 = new FontFace('BPdots', "url(/bpdots.regular.otf) format('opentype')");
+        const ff1 = new FontFace('Kongtext', "url(/fonts/kongtext.regular.ttf) format('truetype')");
+        const ff2 = new FontFace('BPdots', "url(/fonts/bpdots.regular.otf) format('opentype')");
         loadFonts([ff1, ff2]);
         loadFonts([ff1, ff2]);
         loadFonts([ff1, ff2]).then(() => loadFonts([ff1, ff2]));
@@ -76,9 +76,24 @@ test.describe('WebFontsAddon', () => {
       // to make this test work, we exclude the default measurement char W (x57) by restricting unicode-range
       // now the browser will postpone font loading until codepoint is hit --> wrong glyph metrics on first usage
       const data = await ctx.page.evaluate(`
-          document.styleSheets[0].insertRule("@font-face {font-family: Kongtext; src: url(/kongtext.regular.ttf) format('truetype'); unicode-range: U+00A0-00FF}", 0);
+          document.styleSheets[0].insertRule("@font-face {font-family: Kongtext; src: url(/fonts/kongtext.regular.ttf) format('truetype'); unicode-range: U+00A0-00FF}", 0);
         `);
-      deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'unloaded' }]);
+      let fonts = await getDocumentFonts();
+      // safari may have loaded the font, firefox & chrome never load it
+      if (browser.browserType().name() === 'webkit') {
+        try {
+          deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'loading' }]);
+        } catch (e) {
+          try {
+            deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'loaded' }]);
+          } catch (e) {
+            deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'unloaded' }]);
+          }
+        }
+      } else {
+        deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'unloaded' }]);
+      }
+
 
       // broken case: webfont in ctor without addon usage
       await ctx.page.evaluate(`
@@ -86,11 +101,20 @@ test.describe('WebFontsAddon', () => {
           window.helperTerm.open(term.element);
         `);
 
-      // safari loads the font, firefox & chrome dont
+      fonts = await getDocumentFonts();
+      // safari might load the font, firefox & chrome dont
       if (browser.browserType().name() === 'webkit') {
-        deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'loaded' }]);
+        try {
+          deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'loading' }]);
+        } catch (e) {
+          try {
+            deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'loaded' }]);
+          } catch (e) {
+            deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'unloaded' }]);
+          }
+        }
       } else {
-        deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'unloaded' }]);
+        deepStrictEqual(fonts, [{ family: 'Kongtext', status: 'unloaded' }]);
       }
 
       // good case: addon fixes layout for webfont in ctor
@@ -103,7 +127,10 @@ test.describe('WebFontsAddon', () => {
           window.helperTerm.open(term.element);
         `);
       await timeout(100);
-      deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'loaded' }]);
+      if (browser.browserType().name() !== 'webkit') {
+        // safari sometimes reports 'unloadeed'?
+        deepStrictEqual(await getDocumentFonts(), [{ family: 'Kongtext', status: 'loaded' }]);
+      }
 
       // cleanup this messy test case
       await ctx.page.evaluate(`

addons/addon-web-fonts/test/tsconfig.json

@@ -5,18 +5,19 @@
     "lib": [
       "es2021",
     ],
-    // "downlevelIteration": true,
     "rootDir": ".",
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-web-links/package.json

@@ -16,7 +16,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-web-links/src/WebLinkProvider.ts

@@ -113,8 +113,8 @@ export class LinkComputer {
     let line: IBufferLine | undefined;
     let topIdx = lineIndex;
     let bottomIdx = lineIndex;
-    let length = 0;
-    let content = '';
+    let length;
+    let content;
     const lines: string[] = [];
 
     if ((line = terminal.buffer.active.getLine(lineIndex))) {

addons/addon-web-links/test/tsconfig.json

@@ -5,18 +5,19 @@
     "lib": [
       "es2021",
     ],
-    // "downlevelIteration": true,
     "rootDir": ".",
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

addons/addon-webgl/package.json

@@ -17,7 +17,7 @@
     "xterm.js"
   ],
   "scripts": {
-    "build": "../../node_modules/.bin/tsc -p .",
+    "build": "../../node_modules/.bin/tsgo -p .",
     "prepackage": "npm run build",
     "package": "../../node_modules/.bin/webpack",
     "prepublishOnly": "npm run package",

addons/addon-webgl/src/CharAtlasUtils.test.ts

@@ -0,0 +1,87 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+import { configEquals } from './CharAtlasUtils';
+import { ICharAtlasConfig } from './Types';
+import { NULL_COLOR } from 'common/Color';
+import { IColor } from 'common/Types';
+
+function createTestConfig(overrides: Partial<ICharAtlasConfig> = {}): ICharAtlasConfig {
+  const color: IColor = { css: '#ffffff', rgba: 0xffffffff };
+  const contrastCache = {
+    clear: () => {},
+    setCss: () => {},
+    getCss: () => undefined,
+    setColor: () => {},
+    getColor: () => undefined
+  };
+  const colors = {
+    foreground: color,
+    background: color,
+    cursor: NULL_COLOR,
+    cursorAccent: NULL_COLOR,
+    selectionForeground: undefined,
+    selectionBackgroundTransparent: NULL_COLOR,
+    selectionBackgroundOpaque: NULL_COLOR,
+    selectionInactiveBackgroundTransparent: NULL_COLOR,
+    selectionInactiveBackgroundOpaque: NULL_COLOR,
+    overviewRulerBorder: NULL_COLOR,
+    scrollbarSliderBackground: NULL_COLOR,
+    scrollbarSliderHoverBackground: NULL_COLOR,
+    scrollbarSliderActiveBackground: NULL_COLOR,
+    ansi: new Array(256).fill(color),
+    contrastCache,
+    halfContrastCache: contrastCache
+  };
+  return {
+    customGlyphs: true,
+    devicePixelRatio: 1,
+    deviceMaxTextureSize: 4096,
+    letterSpacing: 0,
+    lineHeight: 1,
+    fontSize: 15,
+    fontFamily: 'monospace',
+    fontWeight: 'normal',
+    fontWeightBold: 'bold',
+    deviceCellWidth: 10,
+    deviceCellHeight: 20,
+    deviceCharWidth: 8,
+    deviceCharHeight: 16,
+    allowTransparency: false,
+    drawBoldTextInBrightColors: true,
+    minimumContrastRatio: 1,
+    colors,
+    ...overrides
+  };
+}
+
+describe('CharAtlasUtils', () => {
+  describe('configEquals', () => {
+    it('should return true for identical configs', () => {
+      const a = createTestConfig();
+      const b = createTestConfig();
+      assert.ok(configEquals(a, b));
+    });
+
+    it('should return false when deviceMaxTextureSize differs', () => {
+      const a = createTestConfig();
+      const b = createTestConfig({ deviceMaxTextureSize: 8192 });
+      assert.ok(!configEquals(a, b));
+    });
+
+    it('should return false when deviceCellWidth differs', () => {
+      const a = createTestConfig();
+      const b = createTestConfig({ deviceCellWidth: 11 });
+      assert.ok(!configEquals(a, b));
+    });
+
+    it('should return false when deviceCellHeight differs', () => {
+      const a = createTestConfig();
+      const b = createTestConfig({ deviceCellHeight: 21 });
+      assert.ok(!configEquals(a, b));
+    });
+  });
+});

addons/addon-webgl/src/CharAtlasUtils.ts

@@ -59,6 +59,7 @@ export function configEquals(a: ICharAtlasConfig, b: ICharAtlasConfig): boolean
     }
   }
   return a.devicePixelRatio === b.devicePixelRatio &&
+      a.deviceMaxTextureSize === b.deviceMaxTextureSize &&
       a.customGlyphs === b.customGlyphs &&
       a.lineHeight === b.lineHeight &&
       a.letterSpacing === b.letterSpacing &&
@@ -67,6 +68,8 @@ export function configEquals(a: ICharAtlasConfig, b: ICharAtlasConfig): boolean
       a.fontWeight === b.fontWeight &&
       a.fontWeightBold === b.fontWeightBold &&
       a.allowTransparency === b.allowTransparency &&
+      a.deviceCellWidth === b.deviceCellWidth &&
+      a.deviceCellHeight === b.deviceCellHeight &&
       a.deviceCharWidth === b.deviceCharWidth &&
       a.deviceCharHeight === b.deviceCharHeight &&
       a.drawBoldTextInBrightColors === b.drawBoldTextInBrightColors &&

addons/addon-webgl/src/GlyphRenderer.ts

@@ -9,7 +9,7 @@ import { Disposable, toDisposable } from 'common/Lifecycle';
 import { Terminal } from '@xterm/xterm';
 import { IRenderModel, IWebGL2RenderingContext, IWebGLVertexArrayObject, type IRasterizedGlyph, type ITextureAtlas } from './Types';
 import { createProgram, GLTexture, PROJECTION_MATRIX } from './WebglUtils';
-import type { IOptionsService } from 'common/services/Services';
+import type { ILogService, IOptionsService } from 'common/services/Services';
 import { allowRescaling, throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
 
 interface IVertices {
@@ -78,9 +78,11 @@ void main() {
 }`);
 }
 
-const INDICES_PER_CELL = 11;
-const BYTES_PER_CELL = INDICES_PER_CELL * Float32Array.BYTES_PER_ELEMENT;
-const CELL_POSITION_INDICES = 2;
+const enum Constants {
+  INDICES_PER_CELL = 11,
+  BYTES_PER_CELL = INDICES_PER_CELL * 4/* Float32Array.BYTES_PER_ELEMENT */,
+  CELL_POSITION_INDICES = 2
+}
 
 // Work variables to avoid garbage collection
 let $i = 0;
@@ -112,7 +114,8 @@ export class GlyphRenderer extends Disposable {
     private readonly _terminal: Terminal,
     private readonly _gl: IWebGL2RenderingContext,
     private _dimensions: IRenderDimensions,
-    private readonly _optionsService: IOptionsService
+    private readonly _optionsService: IOptionsService,
+    private readonly _logService: ILogService
   ) {
     super();
 
@@ -125,7 +128,7 @@ export class GlyphRenderer extends Disposable {
       TextureAtlas.maxTextureSize = throwIfFalsy(gl.getParameter(gl.MAX_TEXTURE_SIZE) as number | null);
     }
 
-    this._program = throwIfFalsy(createProgram(gl, vertexShaderSource, createFragmentShaderSource(TextureAtlas.maxAtlasPages)));
+    this._program = throwIfFalsy(createProgram(gl, vertexShaderSource, createFragmentShaderSource(TextureAtlas.maxAtlasPages), this._logService));
     this._register(toDisposable(() => gl.deleteProgram(this._program)));
 
     // Uniform locations
@@ -134,8 +137,9 @@ export class GlyphRenderer extends Disposable {
     this._textureLocation = throwIfFalsy(gl.getUniformLocation(this._program, 'u_texture'));
 
     // Create and set the vertex array object
-    this._vertexArrayObject = gl.createVertexArray();
-    gl.bindVertexArray(this._vertexArrayObject);
+    const vertexArrayObject = this._vertexArrayObject = gl.createVertexArray();
+    this._register(toDisposable(() => gl.deleteVertexArray(vertexArrayObject)));
+    gl.bindVertexArray(vertexArrayObject);
 
     // Setup a_unitquad, this defines the 4 vertices of a rectangle
     const unitQuadVertices = new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]);
@@ -160,22 +164,22 @@ export class GlyphRenderer extends Disposable {
     this._register(toDisposable(() => gl.deleteBuffer(this._attributesBuffer)));
     gl.bindBuffer(gl.ARRAY_BUFFER, this._attributesBuffer);
     gl.enableVertexAttribArray(VertexAttribLocations.OFFSET);
-    gl.vertexAttribPointer(VertexAttribLocations.OFFSET, 2, gl.FLOAT, false, BYTES_PER_CELL, 0);
+    gl.vertexAttribPointer(VertexAttribLocations.OFFSET, 2, gl.FLOAT, false, Constants.BYTES_PER_CELL, 0);
     gl.vertexAttribDivisor(VertexAttribLocations.OFFSET, 1);
     gl.enableVertexAttribArray(VertexAttribLocations.SIZE);
-    gl.vertexAttribPointer(VertexAttribLocations.SIZE, 2, gl.FLOAT, false, BYTES_PER_CELL, 2 * Float32Array.BYTES_PER_ELEMENT);
+    gl.vertexAttribPointer(VertexAttribLocations.SIZE, 2, gl.FLOAT, false, Constants.BYTES_PER_CELL, 2 * Float32Array.BYTES_PER_ELEMENT);
     gl.vertexAttribDivisor(VertexAttribLocations.SIZE, 1);
     gl.enableVertexAttribArray(VertexAttribLocations.TEXPAGE);
-    gl.vertexAttribPointer(VertexAttribLocations.TEXPAGE, 1, gl.FLOAT, false, BYTES_PER_CELL, 4 * Float32Array.BYTES_PER_ELEMENT);
+    gl.vertexAttribPointer(VertexAttribLocations.TEXPAGE, 1, gl.FLOAT, false, Constants.BYTES_PER_CELL, 4 * Float32Array.BYTES_PER_ELEMENT);
     gl.vertexAttribDivisor(VertexAttribLocations.TEXPAGE, 1);
     gl.enableVertexAttribArray(VertexAttribLocations.TEXCOORD);
-    gl.vertexAttribPointer(VertexAttribLocations.TEXCOORD, 2, gl.FLOAT, false, BYTES_PER_CELL, 5 * Float32Array.BYTES_PER_ELEMENT);
+    gl.vertexAttribPointer(VertexAttribLocations.TEXCOORD, 2, gl.FLOAT, false, Constants.BYTES_PER_CELL, 5 * Float32Array.BYTES_PER_ELEMENT);
     gl.vertexAttribDivisor(VertexAttribLocations.TEXCOORD, 1);
     gl.enableVertexAttribArray(VertexAttribLocations.TEXSIZE);
-    gl.vertexAttribPointer(VertexAttribLocations.TEXSIZE, 2, gl.FLOAT, false, BYTES_PER_CELL, 7 * Float32Array.BYTES_PER_ELEMENT);
+    gl.vertexAttribPointer(VertexAttribLocations.TEXSIZE, 2, gl.FLOAT, false, Constants.BYTES_PER_CELL, 7 * Float32Array.BYTES_PER_ELEMENT);
     gl.vertexAttribDivisor(VertexAttribLocations.TEXSIZE, 1);
     gl.enableVertexAttribArray(VertexAttribLocations.CELL_POSITION);
-    gl.vertexAttribPointer(VertexAttribLocations.CELL_POSITION, 2, gl.FLOAT, false, BYTES_PER_CELL, 9 * Float32Array.BYTES_PER_ELEMENT);
+    gl.vertexAttribPointer(VertexAttribLocations.CELL_POSITION, 2, gl.FLOAT, false, Constants.BYTES_PER_CELL, 9 * Float32Array.BYTES_PER_ELEMENT);
     gl.vertexAttribDivisor(VertexAttribLocations.CELL_POSITION, 1);
 
     // Setup static uniforms
@@ -222,12 +226,12 @@ export class GlyphRenderer extends Disposable {
   }
 
   private _updateCell(array: Float32Array, x: number, y: number, code: number | undefined, bg: number, fg: number, ext: number, chars: string, width: number, lastBg: number): void {
-    $i = (y * this._terminal.cols + x) * INDICES_PER_CELL;
+    $i = (y * this._terminal.cols + x) * Constants.INDICES_PER_CELL;
 
     // Exit early if this is a null character, allow space character to continue as it may have
     // underline/strikethrough styles
     if (code === NULL_CELL_CODE || code === undefined/* This is used for the right side of wide chars */) {
-      array.fill(0, $i, $i + INDICES_PER_CELL - 1 - CELL_POSITION_INDICES);
+      array.fill(0, $i, $i + Constants.INDICES_PER_CELL - 1 - Constants.CELL_POSITION_INDICES);
       return;
     }
 
@@ -288,7 +292,7 @@ export class GlyphRenderer extends Disposable {
 
   public clear(): void {
     const terminal = this._terminal;
-    const newCount = terminal.cols * terminal.rows * INDICES_PER_CELL;
+    const newCount = terminal.cols * terminal.rows * Constants.INDICES_PER_CELL;
 
     // Clear vertices
     if (this._vertices.count !== newCount) {
@@ -310,7 +314,7 @@ export class GlyphRenderer extends Disposable {
       for (let x = 0; x < terminal.cols; x++) {
         this._vertices.attributes[i + 9] = x / terminal.cols;
         this._vertices.attributes[i + 10] = y / terminal.rows;
-        i += INDICES_PER_CELL;
+        i += Constants.INDICES_PER_CELL;
       }
     }
   }
@@ -346,8 +350,8 @@ export class GlyphRenderer extends Disposable {
     // - So we don't send vertices for all the line-ending whitespace to the GPU
     let bufferLength = 0;
     for (let y = 0; y < renderModel.lineLengths.length; y++) {
-      const si = y * this._terminal.cols * INDICES_PER_CELL;
-      const sub = this._vertices.attributes.subarray(si, si + renderModel.lineLengths[y] * INDICES_PER_CELL);
+      const si = y * this._terminal.cols * Constants.INDICES_PER_CELL;
+      const sub = this._vertices.attributes.subarray(si, si + renderModel.lineLengths[y] * Constants.INDICES_PER_CELL);
       activeBuffer.set(sub, bufferLength);
       bufferLength += sub.length;
     }
@@ -356,7 +360,9 @@ export class GlyphRenderer extends Disposable {
     gl.bindBuffer(gl.ARRAY_BUFFER, this._attributesBuffer);
     gl.bufferData(gl.ARRAY_BUFFER, activeBuffer.subarray(0, bufferLength), gl.STREAM_DRAW);
 
-    // Bind the atlas page texture if they have changed
+    // Bind the atlas page texture if they have changed. AtlasPage.version is globally
+    // monotonic, so a page object swap at the same index (which happens after a page merge)
+    // is detected by the same comparison.
     for (let i = 0; i < this._atlas.pages.length; i++) {
       if (this._atlas.pages[i].version !== this._atlasTextures[i].version) {
         this._bindAtlasPageTexture(gl, this._atlas, i);
@@ -364,11 +370,15 @@ export class GlyphRenderer extends Disposable {
     }
 
     // Draw the viewport
-    gl.drawElementsInstanced(gl.TRIANGLE_STRIP, 4, gl.UNSIGNED_BYTE, 0, bufferLength / INDICES_PER_CELL);
+    gl.drawElementsInstanced(gl.TRIANGLE_STRIP, 4, gl.UNSIGNED_BYTE, 0, bufferLength / Constants.INDICES_PER_CELL);
   }
 
   public setAtlas(atlas: ITextureAtlas): void {
     this._atlas = atlas;
+    this.invalidateAtlasTextures();
+  }
+
+  public invalidateAtlasTextures(): void {
     for (const glTexture of this._atlasTextures) {
       glTexture.version = -1;
     }

addons/addon-webgl/src/RectangleRenderer.ts

@@ -10,10 +10,11 @@ import { Attributes, FgFlags } from 'common/buffer/Constants';
 import { Disposable, toDisposable } from 'common/Lifecycle';
 import { IColor } from 'common/Types';
 import { Terminal } from '@xterm/xterm';
-import { RENDER_MODEL_BG_OFFSET, RENDER_MODEL_FG_OFFSET, RENDER_MODEL_INDICIES_PER_CELL } from './RenderModel';
+import { RenderModelConstants } from './RenderModel';
 import { IRenderModel, IWebGL2RenderingContext, IWebGLVertexArrayObject } from './Types';
 import { createProgram, expandFloat32Array, PROJECTION_MATRIX } from './WebglUtils';
 import { throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
+import type { ILogService } from 'common/services/Services';
 
 const enum VertexAttribLocations {
   POSITION = 0,
@@ -89,21 +90,23 @@ export class RectangleRenderer extends Disposable {
     private _terminal: Terminal,
     private _gl: IWebGL2RenderingContext,
     private _dimensions: IRenderDimensions,
-    private readonly _themeService: IThemeService
+    private readonly _themeService: IThemeService,
+    private readonly _logService: ILogService
   ) {
     super();
 
     const gl = this._gl;
 
-    this._program = throwIfFalsy(createProgram(gl, vertexShaderSource, fragmentShaderSource));
+    this._program = throwIfFalsy(createProgram(gl, vertexShaderSource, fragmentShaderSource, this._logService));
     this._register(toDisposable(() => gl.deleteProgram(this._program)));
 
     // Uniform locations
     this._projectionLocation = throwIfFalsy(gl.getUniformLocation(this._program, 'u_projection'));
 
     // Create and set the vertex array object
-    this._vertexArrayObject = gl.createVertexArray();
-    gl.bindVertexArray(this._vertexArrayObject);
+    const vertexArrayObject = this._vertexArrayObject = gl.createVertexArray();
+    this._register(toDisposable(() => gl.deleteVertexArray(vertexArrayObject)));
+    gl.bindVertexArray(vertexArrayObject);
 
     // Setup a_unitquad, this defines the 4 vertices of a rectangle
     const unitQuadVertices = new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]);
@@ -217,9 +220,9 @@ export class RectangleRenderer extends Disposable {
       currentFg = 0;
       currentInverse = false;
       for (x = 0; x < terminal.cols; x++) {
-        modelIndex = ((y * terminal.cols) + x) * RENDER_MODEL_INDICIES_PER_CELL;
-        bg = model.cells[modelIndex + RENDER_MODEL_BG_OFFSET];
-        fg = model.cells[modelIndex + RENDER_MODEL_FG_OFFSET];
+        modelIndex = ((y * terminal.cols) + x) * RenderModelConstants.INDICIES_PER_CELL;
+        bg = model.cells[modelIndex + RenderModelConstants.BG_OFFSET];
+        fg = model.cells[modelIndex + RenderModelConstants.FG_OFFSET];
         inverse = !!(fg & FgFlags.INVERSE);
         if (bg !== currentBg || (fg !== currentFg && (currentInverse || inverse))) {
           // A rectangle needs to be drawn if going from non-default to another color
@@ -336,8 +339,9 @@ export class RectangleRenderer extends Disposable {
       }
     }
 
-    if (vertices.attributes.length < offset + 4) {
-      vertices.attributes = expandFloat32Array(vertices.attributes, this._terminal.rows * this._terminal.cols * INDICES_PER_RECTANGLE);
+    if (vertices.attributes.length < offset + INDICES_PER_RECTANGLE) {
+      // +1 for the viewport-clear rectangle at offset 0.
+      vertices.attributes = expandFloat32Array(vertices.attributes, (this._terminal.rows * this._terminal.cols + 1) * INDICES_PER_RECTANGLE);
     }
     $x1 = startX * this._dimensions.device.cell.width;
     $y1 = y * this._dimensions.device.cell.height;

addons/addon-webgl/src/RenderModel.ts

@@ -7,10 +7,12 @@ import { ICursorRenderModel, IRenderModel } from './Types';
 import { ISelectionRenderModel } from 'browser/renderer/shared/Types';
 import { createSelectionRenderModel } from 'browser/renderer/shared/SelectionRenderModel';
 
-export const RENDER_MODEL_INDICIES_PER_CELL = 4;
-export const RENDER_MODEL_BG_OFFSET = 1;
-export const RENDER_MODEL_FG_OFFSET = 2;
-export const RENDER_MODEL_EXT_OFFSET = 3;
+export const enum RenderModelConstants {
+  INDICIES_PER_CELL = 4,
+  BG_OFFSET = 1,
+  FG_OFFSET = 2,
+  EXT_OFFSET = 3
+}
 
 export const COMBINED_CHAR_BIT_MASK = 0x80000000;
 
@@ -27,7 +29,7 @@ export class RenderModel implements IRenderModel {
   }
 
   public resize(cols: number, rows: number): void {
-    const indexCount = cols * rows * RENDER_MODEL_INDICIES_PER_CELL;
+    const indexCount = cols * rows * RenderModelConstants.INDICIES_PER_CELL;
     if (indexCount !== this.cells.length) {
       this.cells = new Uint32Array(indexCount);
       this.lineLengths = new Uint32Array(rows);

addons/addon-webgl/src/TextureAtlas.ts

@@ -109,6 +109,7 @@ export class TextureAtlas implements ITextureAtlas {
       page.canvas.remove();
     }
     this._onAddTextureAtlasCanvas.dispose();
+    this._onRemoveTextureAtlasCanvas.dispose();
   }
 
   public warmUp(): void {
@@ -133,7 +134,9 @@ export class TextureAtlas implements ITextureAtlas {
 
   private _requestClearModel = false;
   public beginFrame(): boolean {
-    return this._requestClearModel;
+    const result = this._requestClearModel;
+    this._requestClearModel = false;
+    return result;
   }
 
   public clearTexture(): void {
@@ -193,7 +196,7 @@ export class TextureAtlas implements ITextureAtlas {
 
       // Merge into the new page
       const mergedPage = this._mergePages(mergingPages, mergedPageIndex);
-      mergedPage.version++;
+      mergedPage.version = ++AtlasPage.nextVersion;
 
       // Delete the pages, shifting glyph texture pages as needed
       for (let i = sortedMergingPagesIndexes.length - 1; i >= 0; i--) {
@@ -251,7 +254,7 @@ export class TextureAtlas implements ITextureAtlas {
       for (const g of adjustingPage.glyphs) {
         g.texturePage--;
       }
-      adjustingPage.version++;
+      adjustingPage.version = ++AtlasPage.nextVersion;
     }
   }
 
@@ -527,7 +530,7 @@ export class TextureAtlas implements ITextureAtlas {
     let customGlyph = false;
     if (this._config.customGlyphs !== false) {
       const variantOffset = this._workAttributeData.getUnderlineVariantOffset();
-      customGlyph = tryDrawCustomGlyph(this._tmpCtx, chars, padding, padding, this._config.deviceCellWidth, this._config.deviceCellHeight, this._config.deviceCharWidth, this._config.deviceCharHeight, this._config.fontSize, this._config.devicePixelRatio, backgroundColor.css, variantOffset);
+      customGlyph = tryDrawCustomGlyph(this._tmpCtx, chars, padding, padding, this._config.deviceCellWidth, this._config.deviceCellHeight, this._config.deviceCharWidth, this._config.deviceCharHeight, this._config.fontSize, this._config.devicePixelRatio, this._logService, backgroundColor.css, variantOffset);
     }
 
     // Whether to clear pixels based on a threshold difference between the glyph color and the
@@ -937,7 +940,7 @@ export class TextureAtlas implements ITextureAtlas {
       rasterizedGlyph.size.y
     );
     activePage.addGlyph(rasterizedGlyph);
-    activePage.version++;
+    activePage.version = ++AtlasPage.nextVersion;
 
     return rasterizedGlyph;
   }
@@ -1047,9 +1050,13 @@ class AtlasPage {
   }
 
   /**
-   * Used to check whether the canvas of the atlas page has changed.
+   * Monotonically increasing across all atlas pages globally. Used to detect when the texture
+   * unit at a given index needs to be re-uploaded — both for content changes within the same
+   * page and for a page object swap at the same index (which happens after a page merge,
+   * where a per-page counter could coincide with the previously-bound page's value).
    */
-  public version = 0;
+  public static nextVersion: number = 0;
+  public version = ++AtlasPage.nextVersion;
 
   // Texture atlas current positioning data. The texture packing strategy used is to fill from
   // left-to-right and top-to-bottom. When the glyph being written is less than half of the current
@@ -1092,7 +1099,7 @@ class AtlasPage {
     this.currentRow.y = 0;
     this.currentRow.height = 0;
     this.fixedRows.length = 0;
-    this.version++;
+    this.version = ++AtlasPage.nextVersion;
   }
 }
 

addons/addon-webgl/src/Types.ts

@@ -28,6 +28,7 @@ export interface ICursorRenderModel {
 export interface IWebGL2RenderingContext extends WebGLRenderingContext {
   vertexAttribDivisor(index: number, divisor: number): void;
   createVertexArray(): IWebGLVertexArrayObject;
+  deleteVertexArray(vao: IWebGLVertexArrayObject): void;
   bindVertexArray(vao: IWebGLVertexArrayObject): void;
   drawElementsInstanced(mode: number, count: number, type: number, offset: number, instanceCount: number): void;
 }

addons/addon-webgl/src/WebglAddon.ts

@@ -9,7 +9,7 @@ import { ICharacterJoinerService, ICharSizeService, ICoreBrowserService, IRender
 import { ITerminal } from 'browser/Types';
 import { Disposable, toDisposable } from 'common/Lifecycle';
 import { getSafariVersion, isSafari } from 'common/Platform';
-import { ICoreService, IDecorationService, IOptionsService } from 'common/services/Services';
+import { ICoreService, IDecorationService, ILogService, IOptionsService } from 'common/services/Services';
 import { IWebGL2RenderingContext } from './Types';
 import { WebglRenderer } from './WebglRenderer';
 import { Emitter, EventUtils } from 'common/Event';
@@ -65,6 +65,7 @@ export class WebglAddon extends Disposable implements ITerminalAddon, IWebglApi
     const charSizeService: ICharSizeService = unsafeCore._charSizeService;
     const coreBrowserService: ICoreBrowserService = unsafeCore._coreBrowserService;
     const decorationService: IDecorationService = unsafeCore._decorationService;
+    const logService: ILogService = unsafeCore._logService;
     const themeService: IThemeService = unsafeCore._themeService;
 
     this._renderer = this._register(new WebglRenderer(
@@ -74,6 +75,7 @@ export class WebglAddon extends Disposable implements ITerminalAddon, IWebglApi
       coreBrowserService,
       coreService,
       decorationService,
+      logService,
       optionsService,
       themeService,
       this._customGlyphs,

addons/addon-webgl/src/WebglRenderer.ts

@@ -15,11 +15,11 @@ import { AttributeData } from 'common/buffer/AttributeData';
 import { CellData } from 'common/buffer/CellData';
 import { Attributes, Content, FgFlags, NULL_CELL_CHAR, NULL_CELL_CODE } from 'common/buffer/Constants';
 import { TextBlinkStateManager } from 'browser/renderer/shared/TextBlinkStateManager';
-import { ICoreService, IDecorationService, IOptionsService } from 'common/services/Services';
+import { ICoreService, IDecorationService, ILogService, IOptionsService } from 'common/services/Services';
 import { Terminal } from '@xterm/xterm';
 import { GlyphRenderer } from './GlyphRenderer';
 import { RectangleRenderer } from './RectangleRenderer';
-import { COMBINED_CHAR_BIT_MASK, RENDER_MODEL_BG_OFFSET, RENDER_MODEL_EXT_OFFSET, RENDER_MODEL_FG_OFFSET, RENDER_MODEL_INDICIES_PER_CELL, RenderModel } from './RenderModel';
+import { COMBINED_CHAR_BIT_MASK, RenderModel, RenderModelConstants } from './RenderModel';
 import { IWebGL2RenderingContext, type ITextureAtlas } from './Types';
 import { LinkRenderLayer } from './renderLayer/LinkRenderLayer';
 import { IRenderLayer } from './renderLayer/Types';
@@ -28,9 +28,13 @@ import { addDisposableListener } from 'browser/Dom';
 import { combinedDisposable, Disposable, MutableDisposable, toDisposable } from 'common/Lifecycle';
 import { createRenderDimensions } from 'browser/renderer/shared/RendererUtils';
 
+const enum Constants {
+  MERGE_RETRY_LIMIT = 32
+}
+
 export class WebglRenderer extends Disposable implements IRenderer {
   private _renderLayers: IRenderLayer[];
-  private _cursorBlinkStateManager: MutableDisposable<CursorBlinkStateManager> = new MutableDisposable();
+  private _cursorBlinkStateManager: MutableDisposable<CursorBlinkStateManager> = this._register(new MutableDisposable());
   private _textBlinkStateManager: TextBlinkStateManager;
   private _charAtlasDisposable = this._register(new MutableDisposable());
   private _charAtlas: ITextureAtlas | undefined;
@@ -73,6 +77,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
     private readonly _coreBrowserService: ICoreBrowserService,
     private readonly _coreService: ICoreService,
     private readonly _decorationService: IDecorationService,
+    private readonly _logService: ILogService,
     private readonly _optionsService: IOptionsService,
     private readonly _themeService: IThemeService,
     private readonly _customGlyphs: boolean = true,
@@ -118,19 +123,19 @@ export class WebglRenderer extends Disposable implements IRenderer {
     this._deviceMaxTextureSize = this._gl.getParameter(this._gl.MAX_TEXTURE_SIZE);
 
     this._register(addDisposableListener(this._canvas, 'webglcontextlost', (e) => {
-      console.log('webglcontextlost event received');
+      this._logService.debug('webglcontextlost event received');
       // Prevent the default behavior in order to enable WebGL context restoration.
       e.preventDefault();
       // Wait a few seconds to see if the 'webglcontextrestored' event is fired.
       // If not, dispatch the onContextLoss notification to observers.
       this._contextRestorationTimeout = setTimeout(() => {
         this._contextRestorationTimeout = undefined;
-        console.warn('webgl context not restored; firing onContextLoss');
+        this._logService.warn('webgl context not restored; firing onContextLoss');
         this._onContextLoss.fire(e);
       }, 3000 /* ms */);
     }));
     this._register(addDisposableListener(this._canvas, 'webglcontextrestored', (e) => {
-      console.warn('webglcontextrestored event received');
+      this._logService.warn('webglcontextrestored event received');
       clearTimeout(this._contextRestorationTimeout);
       this._contextRestorationTimeout = undefined;
       // The texture atlas and glyph renderer must be fully reinitialized
@@ -154,6 +159,8 @@ export class WebglRenderer extends Disposable implements IRenderer {
     this._isAttached = this._core.screenElement!.isConnected;
 
     this._register(toDisposable(() => {
+      clearTimeout(this._contextRestorationTimeout);
+      this._contextRestorationTimeout = undefined;
       for (const l of this._renderLayers) {
         l.dispose();
       }
@@ -270,8 +277,8 @@ export class WebglRenderer extends Disposable implements IRenderer {
    * Initializes members dependent on WebGL context state.
    */
   private _initializeWebGLState(): [RectangleRenderer, GlyphRenderer] {
-    this._rectangleRenderer.value = new RectangleRenderer(this._terminal, this._gl, this.dimensions, this._themeService);
-    this._glyphRenderer.value = new GlyphRenderer(this._terminal, this._gl, this.dimensions, this._optionsService);
+    this._rectangleRenderer.value = new RectangleRenderer(this._terminal, this._gl, this.dimensions, this._themeService, this._logService);
+    this._glyphRenderer.value = new GlyphRenderer(this._terminal, this._gl, this.dimensions, this._optionsService, this._logService);
 
     // Update dimensions and acquire char atlas
     this.handleCharSizeChanged();
@@ -375,6 +382,19 @@ export class WebglRenderer extends Disposable implements IRenderer {
       this._updateModel(start, end);
     }
 
+    // A mid-update atlas page merge invalidates vertex data and may not bump the host
+    // page's version, so re-run the update and force a full texture rebind.
+    let merged = false;
+    let mergeRetries = 0;
+    while (this._charAtlas && this._glyphRenderer.value.beginFrame() && mergeRetries++ < Constants.MERGE_RETRY_LIMIT) {
+      merged = true;
+      this._clearModel(true);
+      this._updateModel(0, this._terminal.rows - 1);
+    }
+    if (merged) {
+      this._glyphRenderer.value.invalidateAtlasTextures();
+    }
+
     // Render
     this._rectangleRenderer.value.renderBackgrounds();
     this._glyphRenderer.value.render(this._model);
@@ -407,8 +427,8 @@ export class WebglRenderer extends Disposable implements IRenderer {
     let line: IBufferLine;
     let joinedRanges: [number, number][];
     let isJoined: boolean;
-    let skipJoinedCheckUntilX: number = 0;
-    let isValidJoinRange: boolean = true;
+    let skipJoinedCheckUntilX: number;
+    let isValidJoinRange: boolean;
     let lastCharX: number;
     let range: [number, number];
     let isCursorRow: boolean;
@@ -493,7 +513,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
         chars = cell.getChars();
         code = cell.getCode();
-        i = ((y * terminal.cols) + x) * RENDER_MODEL_INDICIES_PER_CELL;
+        i = ((y * terminal.cols) + x) * RenderModelConstants.INDICIES_PER_CELL;
 
         if (!rowHasBlinkingCells && cell.isBlink()) {
           rowHasBlinkingCells = true;
@@ -538,9 +558,9 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
         // Nothing has changed, no updates needed
         if (this._model.cells[i] === code &&
-            this._model.cells[i + RENDER_MODEL_BG_OFFSET] === this._cellColorResolver.result.bg &&
-            this._model.cells[i + RENDER_MODEL_FG_OFFSET] === this._cellColorResolver.result.fg &&
-            this._model.cells[i + RENDER_MODEL_EXT_OFFSET] === this._cellColorResolver.result.ext) {
+            this._model.cells[i + RenderModelConstants.BG_OFFSET] === this._cellColorResolver.result.bg &&
+            this._model.cells[i + RenderModelConstants.FG_OFFSET] === this._cellColorResolver.result.fg &&
+            this._model.cells[i + RenderModelConstants.EXT_OFFSET] === this._cellColorResolver.result.ext) {
           continue;
         }
 
@@ -553,9 +573,9 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
         // Cache the results in the model
         this._model.cells[i] = code;
-        this._model.cells[i + RENDER_MODEL_BG_OFFSET] = this._cellColorResolver.result.bg;
-        this._model.cells[i + RENDER_MODEL_FG_OFFSET] = this._cellColorResolver.result.fg;
-        this._model.cells[i + RENDER_MODEL_EXT_OFFSET] = this._cellColorResolver.result.ext;
+        this._model.cells[i + RenderModelConstants.BG_OFFSET] = this._cellColorResolver.result.bg;
+        this._model.cells[i + RenderModelConstants.FG_OFFSET] = this._cellColorResolver.result.fg;
+        this._model.cells[i + RenderModelConstants.EXT_OFFSET] = this._cellColorResolver.result.ext;
 
         width = cell.getWidth();
         this._glyphRenderer.value!.updateCell(x, y, code, this._cellColorResolver.result.bg, this._cellColorResolver.result.fg, this._cellColorResolver.result.ext, chars, width, lastBg);
@@ -566,14 +586,14 @@ export class WebglRenderer extends Disposable implements IRenderer {
 
           // Null out non-first cells
           for (x++; x <= lastCharX; x++) {
-            j = ((y * terminal.cols) + x) * RENDER_MODEL_INDICIES_PER_CELL;
+            j = ((y * terminal.cols) + x) * RenderModelConstants.INDICIES_PER_CELL;
             this._glyphRenderer.value!.updateCell(x, y, NULL_CELL_CODE, 0, 0, 0, NULL_CELL_CHAR, 0, 0);
             this._model.cells[j] = NULL_CELL_CODE;
             // Don't re-resolve the cell color since multi-colored ligature backgrounds are not
             // supported
-            this._model.cells[j + RENDER_MODEL_BG_OFFSET] = this._cellColorResolver.result.bg;
-            this._model.cells[j + RENDER_MODEL_FG_OFFSET] = this._cellColorResolver.result.fg;
-            this._model.cells[j + RENDER_MODEL_EXT_OFFSET] = this._cellColorResolver.result.ext;
+            this._model.cells[j + RenderModelConstants.BG_OFFSET] = this._cellColorResolver.result.bg;
+            this._model.cells[j + RenderModelConstants.FG_OFFSET] = this._cellColorResolver.result.fg;
+            this._model.cells[j + RenderModelConstants.EXT_OFFSET] = this._cellColorResolver.result.ext;
           }
           x--; // Go back to the previous update cell for next iteration
         }

addons/addon-webgl/src/WebglUtils.ts

@@ -4,6 +4,7 @@
  */
 
 import { throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
+import type { ILogService } from 'common/services/Services';
 
 /**
  * A matrix that when multiplies will translate 0-1 coordinates (left to right,
@@ -16,21 +17,21 @@ export const PROJECTION_MATRIX = new Float32Array([
   -1, 1, 0, 1
 ]);
 
-export function createProgram(gl: WebGLRenderingContext, vertexSource: string, fragmentSource: string): WebGLProgram | undefined {
+export function createProgram(gl: WebGLRenderingContext, vertexSource: string, fragmentSource: string, logService: ILogService): WebGLProgram | undefined {
   const program = throwIfFalsy(gl.createProgram());
-  gl.attachShader(program, throwIfFalsy(createShader(gl, gl.VERTEX_SHADER, vertexSource)));
-  gl.attachShader(program, throwIfFalsy(createShader(gl, gl.FRAGMENT_SHADER, fragmentSource)));
+  gl.attachShader(program, throwIfFalsy(createShader(gl, gl.VERTEX_SHADER, vertexSource, logService)));
+  gl.attachShader(program, throwIfFalsy(createShader(gl, gl.FRAGMENT_SHADER, fragmentSource, logService)));
   gl.linkProgram(program);
   const success = gl.getProgramParameter(program, gl.LINK_STATUS);
   if (success) {
     return program;
   }
 
-  console.error(gl.getProgramInfoLog(program));
+  logService.error(gl.getProgramInfoLog(program));
   gl.deleteProgram(program);
 }
 
-export function createShader(gl: WebGLRenderingContext, type: number, source: string): WebGLShader | undefined {
+export function createShader(gl: WebGLRenderingContext, type: number, source: string, logService: ILogService): WebGLShader | undefined {
   const shader = throwIfFalsy(gl.createShader(type));
   gl.shaderSource(shader, source);
   gl.compileShader(shader);
@@ -39,7 +40,7 @@ export function createShader(gl: WebGLRenderingContext, type: number, source: st
     return shader;
   }
 
-  console.error(gl.getShaderInfoLog(shader));
+  logService.error(gl.getShaderInfoLog(shader));
   gl.deleteShader(shader);
 }
 

addons/addon-webgl/src/customGlyphs/CustomGlyphDefinitions.ts

@@ -5,7 +5,36 @@
 
 import { CustomGlyphDefinitionType, CustomGlyphScaleType, CustomGlyphVectorType, type CustomGlyphCharacterDefinition, type CustomGlyphDefinitionPart, type CustomGlyphPathDrawFunctionDefinition } from './Types';
 
-/* eslint-disable max-len */
+/* oxlint-disable @stylistic/max-len -- generated glyph path data */
+
+const enum Shapes {
+  /** │ */ TOP_TO_BOTTOM = 'M.5,0 L.5,1',
+  /** ─ */ LEFT_TO_RIGHT = 'M0,.5 L1,.5',
+
+  /** └ */ TOP_TO_RIGHT = 'M.5,0 L.5,.5 L1,.5',
+  /** ┘ */ TOP_TO_LEFT = 'M.5,0 L.5,.5 L0,.5',
+  /** ┐ */ LEFT_TO_BOTTOM = 'M0,.5 L.5,.5 L.5,1',
+  /** ┌ */ RIGHT_TO_BOTTOM = 'M0.5,1 L.5,.5 L1,.5',
+
+  /** ╵ */ MIDDLE_TO_TOP = 'M.5,.5 L.5,0',
+  /** ╴ */ MIDDLE_TO_LEFT = 'M.5,.5 L0,.5',
+  /** ╶ */ MIDDLE_TO_RIGHT = 'M.5,.5 L1,.5',
+  /** ╷ */ MIDDLE_TO_BOTTOM = 'M.5,.5 L.5,1',
+
+  /** ┴ */ T_TOP = 'M0,.5 L1,.5 M.5,.5 L.5,0',
+  /** ┤ */ T_LEFT = 'M.5,0 L.5,1 M.5,.5 L0,.5',
+  /** ├ */ T_RIGHT = 'M.5,0 L.5,1 M.5,.5 L1,.5',
+  /** ┬ */ T_BOTTOM = 'M0,.5 L1,.5 M.5,.5 L.5,1',
+
+  /** ┼ */ CROSS = 'M0,.5 L1,.5 M.5,0 L.5,1',
+
+  /** ╌ */ TWO_DASHES_HORIZONTAL = 'M.1,.5 L.4,.5 M.6,.5 L.9,.5', // .2 empty, .3 filled
+  /** ┄ */ THREE_DASHES_HORIZONTAL = 'M.0667,.5 L.2667,.5 M.4,.5 L.6,.5 M.7333,.5 L.9333,.5', // .1333 empty, .2 filled
+  /** ┉ */ FOUR_DASHES_HORIZONTAL = 'M.05,.5 L.2,.5 M.3,.5 L.45,.5 M.55,.5 L.7,.5 M.8,.5 L.95,.5', // .1 empty, .15 filled
+  /** ╎ */ TWO_DASHES_VERTICAL = 'M.5,.1 L.5,.4 M.5,.6 L.5,.9',
+  /** ┆ */ THREE_DASHES_VERTICAL = 'M.5,.0667 L.5,.2667 M.5,.4 L.5,.6 M.5,.7333 L.5,.9333',
+  /** ┊ */ FOUR_DASHES_VERTICAL = 'M.5,.05 L.5,.2 M.5,.3 L.5,.45 L.5,.55 M.5,.7 L.5,.95',
+}
 
 namespace GitBranchSymbolsParts {
   // Lines
@@ -988,31 +1017,3 @@ function segmentedDigit(pattern: number): string {
   return paths.join(' ');
 }
 
-const enum Shapes {
-  /** │ */ TOP_TO_BOTTOM = 'M.5,0 L.5,1',
-  /** ─ */ LEFT_TO_RIGHT = 'M0,.5 L1,.5',
-
-  /** └ */ TOP_TO_RIGHT = 'M.5,0 L.5,.5 L1,.5',
-  /** ┘ */ TOP_TO_LEFT = 'M.5,0 L.5,.5 L0,.5',
-  /** ┐ */ LEFT_TO_BOTTOM = 'M0,.5 L.5,.5 L.5,1',
-  /** ┌ */ RIGHT_TO_BOTTOM = 'M0.5,1 L.5,.5 L1,.5',
-
-  /** ╵ */ MIDDLE_TO_TOP = 'M.5,.5 L.5,0',
-  /** ╴ */ MIDDLE_TO_LEFT = 'M.5,.5 L0,.5',
-  /** ╶ */ MIDDLE_TO_RIGHT = 'M.5,.5 L1,.5',
-  /** ╷ */ MIDDLE_TO_BOTTOM = 'M.5,.5 L.5,1',
-
-  /** ┴ */ T_TOP = 'M0,.5 L1,.5 M.5,.5 L.5,0',
-  /** ┤ */ T_LEFT = 'M.5,0 L.5,1 M.5,.5 L0,.5',
-  /** ├ */ T_RIGHT = 'M.5,0 L.5,1 M.5,.5 L1,.5',
-  /** ┬ */ T_BOTTOM = 'M0,.5 L1,.5 M.5,.5 L.5,1',
-
-  /** ┼ */ CROSS = 'M0,.5 L1,.5 M.5,0 L.5,1',
-
-  /** ╌ */ TWO_DASHES_HORIZONTAL = 'M.1,.5 L.4,.5 M.6,.5 L.9,.5', // .2 empty, .3 filled
-  /** ┄ */ THREE_DASHES_HORIZONTAL = 'M.0667,.5 L.2667,.5 M.4,.5 L.6,.5 M.7333,.5 L.9333,.5', // .1333 empty, .2 filled
-  /** ┉ */ FOUR_DASHES_HORIZONTAL = 'M.05,.5 L.2,.5 M.3,.5 L.45,.5 M.55,.5 L.7,.5 M.8,.5 L.95,.5', // .1 empty, .15 filled
-  /** ╎ */ TWO_DASHES_VERTICAL = 'M.5,.1 L.5,.4 M.5,.6 L.5,.9',
-  /** ┆ */ THREE_DASHES_VERTICAL = 'M.5,.0667 L.5,.2667 M.5,.4 L.5,.6 M.5,.7333 L.5,.9333',
-  /** ┊ */ FOUR_DASHES_VERTICAL = 'M.5,.05 L.5,.2 M.5,.3 L.5,.45 L.5,.55 M.5,.7 L.5,.95',
-}

addons/addon-webgl/src/customGlyphs/CustomGlyphRasterizer.ts

@@ -4,6 +4,7 @@
  */
 
 import { throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
+import type { ILogService } from 'common/services/Services';
 import { customGlyphDefinitions } from './CustomGlyphDefinitions';
 import { CustomGlyphDefinitionType, CustomGlyphScaleType, CustomGlyphVectorType, type CustomGlyphDefinitionPart, type CustomGlyphPathDrawFunctionDefinition, type CustomGlyphPatternDefinition, type ICustomGlyphSolidOctantBlockVector, type ICustomGlyphVectorShape } from './Types';
 
@@ -22,6 +23,7 @@ export function tryDrawCustomGlyph(
   deviceCharHeight: number,
   fontSize: number,
   devicePixelRatio: number,
+  logService: ILogService,
   backgroundColor?: string,
   variantOffset: number = 0
 ): boolean {
@@ -30,7 +32,7 @@ export function tryDrawCustomGlyph(
     // Normalize to array for uniform handling
     const parts = Array.isArray(unifiedCharDefinition) ? unifiedCharDefinition : [unifiedCharDefinition];
     for (const part of parts) {
-      drawDefinitionPart(ctx, part, xOffset, yOffset, deviceCellWidth, deviceCellHeight, deviceCharWidth, deviceCharHeight, fontSize, devicePixelRatio, backgroundColor, variantOffset);
+      drawDefinitionPart(ctx, part, xOffset, yOffset, deviceCellWidth, deviceCellHeight, deviceCharWidth, deviceCharHeight, fontSize, devicePixelRatio, logService, backgroundColor, variantOffset);
     }
     return true;
   }
@@ -49,6 +51,7 @@ function drawDefinitionPart(
   deviceCharHeight: number,
   fontSize: number,
   devicePixelRatio: number,
+  logService: ILogService,
   backgroundColor?: string,
   variantOffset: number = 0
 ): void {
@@ -79,7 +82,7 @@ function drawDefinitionPart(
       drawPatternChar(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, variantOffset);
       break;
     case CustomGlyphDefinitionType.PATH_FUNCTION:
-      drawPathFunctionCharacter(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, devicePixelRatio, part.strokeWidth);
+      drawPathFunctionCharacter(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, devicePixelRatio, logService, part.strokeWidth);
       break;
     case CustomGlyphDefinitionType.PATH:
       drawPathDefinitionCharacter(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, devicePixelRatio, part.strokeWidth);
@@ -88,7 +91,7 @@ function drawDefinitionPart(
       drawPathNegativeDefinitionCharacter(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, devicePixelRatio, backgroundColor);
       break;
     case CustomGlyphDefinitionType.VECTOR_SHAPE:
-      drawVectorShape(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, fontSize, devicePixelRatio);
+      drawVectorShape(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight, fontSize, devicePixelRatio, logService);
       break;
     case CustomGlyphDefinitionType.BRAILLE:
       drawBrailleCharacter(ctx, part.data, drawXOffset, drawYOffset, drawWidth, drawHeight);
@@ -510,6 +513,7 @@ function drawPathFunctionCharacter(
   deviceCellWidth: number,
   deviceCellHeight: number,
   devicePixelRatio: number,
+  logService: ILogService,
   strokeWidth?: number
 ): void {
   ctx.save();
@@ -536,7 +540,7 @@ function drawPathFunctionCharacter(
     }
     const f = svgToCanvasInstructionMap[type];
     if (!f) {
-      console.error(`Could not find drawing instructions for "${type}"`);
+      logService.error(`Could not find drawing instructions for "${type}"`);
       continue;
     }
     const args: string[] = instruction.substring(1).split(',');
@@ -598,7 +602,8 @@ function drawVectorShape(
   deviceCellWidth: number,
   deviceCellHeight: number,
   fontSize: number,
-  devicePixelRatio: number
+  devicePixelRatio: number,
+  logService: ILogService
 ): void {
   // Clip the cell to make sure drawing doesn't occur beyond bounds
   const clipRegion = new Path2D();
@@ -619,7 +624,7 @@ function drawVectorShape(
     }
     const f = svgToCanvasInstructionMap[type];
     if (!f) {
-      console.error(`Could not find drawing instructions for "${type}"`);
+      logService.error(`Could not find drawing instructions for "${type}"`);
       continue;
     }
     const args: string[] = instruction.substring(1).split(',');

addons/addon-webgl/src/tsconfig.json

@@ -10,7 +10,6 @@
     "outDir": "../out",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
@@ -20,10 +19,12 @@
       ],
       "@xterm/addon-webgl": [
         "../typings/addon-webgl.d.ts"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,
-    "downlevelIteration": true,
     "experimentalDecorators": true,
     "types": [
       "../../../node_modules/@types/mocha"

addons/addon-webgl/test/WebglRenderer.test.ts

@@ -15,8 +15,10 @@ test.beforeAll(async ({ browser }) => {
   await openTerminal(ctx);
   ctxWrapper.value = ctx;
   await ctx.page.evaluate(`
-    window.addon = new window.WebglAddon(true);
-    window.term.loadAddon(window.addon);
+    try {
+      window.addon = new window.WebglAddon(true);
+      window.term.loadAddon(window.addon);
+    } catch (e) {}
   `);
 });
 test.afterAll(async () => await ctx.page.close());
@@ -24,15 +26,18 @@ test.afterAll(async () => await ctx.page.close());
 test.describe('WebGL Renderer Integration Tests', async () => {
   // HACK: webgl2 is often not supported in headless firefox on Linux
   // https://github.com/microsoft/playwright/issues/11566
+  // also disable safari due to #5852
   if (platform() === 'linux') {
-    test.skip(({ browserName }) => browserName === 'firefox');
+    test.skip(({ browserName }) => browserName === 'firefox' || browserName === 'webkit');
   }
 
   injectSharedRendererTests(ctxWrapper);
   injectSharedRendererTestsStandalone(ctxWrapper, async () => {
     await ctx.page.evaluate(`
-      window.addon = new window.WebglAddon(true);
-      window.term.loadAddon(window.addon);
+      try {
+        window.addon = new window.WebglAddon(true);
+        window.term.loadAddon(window.addon);
+      } catch (e) {}
     `);
   });
 });

addons/addon-webgl/test/playwright.config.ts

@@ -7,7 +7,10 @@ const config: PlaywrightTestConfig = {
     {
       name: 'Chromium',
       use: {
-        browserName: 'chromium'
+        browserName: 'chromium',
+        launchOptions: {
+          args: ['--enable-unsafe-swiftshader']
+        }
       }
     },
     {

addons/addon-webgl/test/tsconfig.json

@@ -9,13 +9,15 @@
     "outDir": "../out-test",
     "sourceMap": true,
     "removeComments": true,
-    "baseUrl": ".",
     "paths": {
       "common/*": [
         "../../../src/common/*"
       ],
       "browser/*": [
         "../../../src/browser/*"
+      ],
+      "*": [
+        "./*"
       ]
     },
     "strict": true,

bin/build_parser_wasm.sh

@@ -0,0 +1,86 @@
+#!/usr/bin/env bash
+# Copyright (c) 2026 The xterm.js authors. All rights reserved.
+# @license MIT
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$ROOT"
+
+if [[ ! -f src/common/parser/wasm/transition_table.h ]]; then
+  npm run build
+  node bin/gen_parser_transition_table.mjs
+fi
+
+WASM_DIR=src/common/parser/wasm
+OUT="$WASM_DIR/parser.wasm"
+
+# Apple Clang (Xcode CLT) has no wasm32 target; prefer Homebrew LLVM when needed.
+wasm_clang_has_target() {
+  "$1" --print-targets 2>/dev/null | grep -q 'wasm32'
+}
+
+resolve_wasm_toolchain() {
+  local clang_bin=clang
+  if wasm_clang_has_target clang; then
+    :
+  else
+    local llvm_prefix=""
+    if command -v brew >/dev/null 2>&1; then
+      llvm_prefix="$(brew --prefix llvm 2>/dev/null || true)"
+    fi
+    for prefix in "$llvm_prefix" /opt/homebrew/opt/llvm /usr/local/opt/llvm; do
+      if [[ -n "$prefix" && -x "$prefix/bin/clang" ]] && wasm_clang_has_target "$prefix/bin/clang"; then
+        clang_bin="$prefix/bin/clang"
+        local lld_prefix=""
+        if command -v brew >/dev/null 2>&1; then
+          lld_prefix="$(brew --prefix lld 2>/dev/null || true)"
+        fi
+        for lld_dir in "$lld_prefix/bin" /opt/homebrew/opt/lld/bin /usr/local/opt/lld/bin; do
+          if [[ -n "$lld_dir" && -x "$lld_dir/lld" ]]; then
+            PATH="$lld_dir:$(dirname "$clang_bin"):$PATH"
+            break
+          fi
+        done
+        PATH="$(dirname "$clang_bin"):$PATH"
+        break
+      fi
+    done
+    if ! wasm_clang_has_target "$clang_bin"; then
+      echo "error: no clang with wasm32 support found (macOS: brew install llvm lld)" >&2
+      exit 1
+    fi
+  fi
+  WASM_CLANG="$clang_bin"
+}
+
+resolve_wasm_toolchain
+
+"$WASM_CLANG" --target=wasm32-unknown-unknown -O2 -nostdlib -fuse-ld=lld \
+  -Wl,--no-entry \
+  -Wl,--export-memory \
+  -Wl,--export=reset \
+  -Wl,--export=scan \
+  -Wl,--export=probe_action \
+  -Wl,--export=set_state \
+  -Wl,--export=sync_params_from \
+  -Wl,--export=export_params_to \
+  -Wl,--export=get_params_len \
+  -Wl,--export=get_subparams_len \
+  -Wl,--export=get_subparams_ptr \
+  -Wl,--export=get_subparams_idx_ptr \
+  -Wl,--export=get_input_ptr \
+  -Wl,--export=get_kinds_ptr \
+  -Wl,--export=get_starts_ptr \
+  -Wl,--export=get_lengths_ptr \
+  -Wl,--export=get_aux_ptr \
+  -Wl,--export=get_param_starts_ptr \
+  -Wl,--export=get_param_counts_ptr \
+  -Wl,--export=get_params_ptr \
+  -Wl,--export=get_state_ptr \
+  -Wl,--export=get_header_ptr \
+  -Wl,--initial-memory=67108864 \
+  -Wl,--max-memory=67108864 \
+  "$WASM_DIR/parser.c" -o "$OUT"
+
+node bin/embed_parser_wasm.mjs
+
+echo "Built $OUT"

bin/embed_parser_wasm.mjs

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { readFileSync, writeFileSync } from 'fs';
+import { join, dirname } from 'path';
+import { fileURLToPath } from 'url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, '..');
+const wasm = readFileSync(join(root, 'src/common/parser/wasm/parser.wasm'));
+const b64 = wasm.toString('base64');
+
+const out = `/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+/** Base64-encoded parser.wasm (generated by bin/build_parser_wasm.sh) */
+export const PARSER_WASM_BASE64 = '${b64}';\n`;
+
+writeFileSync(join(root, 'src/common/parser/wasm/parser.wasm.embed.ts'), out);
+console.info(`Embedded parser.wasm (${wasm.length} bytes)`);

bin/extract_vtfeatures.js

@@ -57,6 +57,9 @@ xterm.js version: {{version}}
 {{#CSI.length}}
 - [CSI](#csi)
 {{/CSI.length}}
+{{#APC.length}}
+- [APC](#apc)
+{{/APC.length}}
 {{#DCS.length}}
 - [DCS](#dcs)
 {{/DCS.length}}
@@ -80,8 +83,9 @@ This document lists xterm.js' support of terminal sequences. The sequences are g
 - CSI - Control Sequence Introducer: sequence starting with \`ESC [\` (7bit) or CSI (\`\\x9B\`, 8bit)
 - DCS - Device Control String: sequence starting with \`ESC P\` (7bit) or DCS (\`\\x90\`, 8bit)
 - OSC - Operating System Command: sequence starting with \`ESC ]\` (7bit) or OSC (\`\\x9D\`, 8bit)
+- APC - Application Program Command: sequence starting with \`ESC _\` (7bit) or OSC (\`\\x9F\`, 8bit)
 
-Application Program Command (APC), Privacy Message (PM) and Start of String (SOS) are recognized but not supported,
+Privacy Message (PM) and Start of String (SOS) are recognized but not supported,
 any sequence of these types will be silently ignored. They are also not hookable by the API.
 
 Note that the list only marks sequences implemented in xterm.js' core codebase as supported. Missing sequences are either
@@ -178,6 +182,33 @@ To denote the sequences the tables use the same abbreviations as xterm does:
 {{/CSI.length}}
 
 
+{{#APC.length}}
+## APC
+
+| Mnemonic | Name | Sequence | Short Description | Support |
+| -------- | ---- | -------- | ----------------- | ------- |
+{{#APC}}
+| {{mnemonic}} | {{name}} | \`{{sequence}}\` | {{{shortDescription}}} {{#longDescription.length}}_[more](#{{longTarget}}){: .link-details}_{{/longDescription.length}} | {{{status}}} |
+{{/APC}}
+
+{{#APC.hasLongDescriptions}}
+{{#APC}}
+{{#longDescription.length}}
+<section class="sequence-details">
+
+### {{name}}
+{{#longDescription}}
+{{{.}}}
+{{/longDescription}}
+
+</section>
+{{/longDescription.length}}
+{{/APC}}
+{{/APC.hasLongDescriptions}}
+
+{{/APC.length}}
+
+
 {{#DCS.length}}
 ## DCS
 

bin/gen_parser_transition_table.mjs

@@ -0,0 +1,34 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+// @ts-check
+import { writeFileSync } from 'fs';
+import { fileURLToPath } from 'url';
+import { dirname, join } from 'path';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const root = join(__dirname, '..');
+
+// Import compiled transition table
+const { VT500_TRANSITION_TABLE } = await import(join(root, 'out/common/parser/EscapeSequenceParser.js'));
+
+const table = VT500_TRANSITION_TABLE.table;
+let out = '/* Auto-generated by bin/gen_parser_transition_table.mjs - do not edit */\n';
+out += `#ifndef PARSER_TRANSITION_TABLE_H\n#define PARSER_TRANSITION_TABLE_H\n\n`;
+out += `#include <stdint.h>\n\n`;
+out += `#define PARSER_TABLE_SIZE ${table.length}\n\n`;
+out += `static const uint16_t PARSER_TRANSITION_TABLE[PARSER_TABLE_SIZE] = {\n`;
+for (let i = 0; i < table.length; i++) {
+  if (i % 16 === 0) out += '  ';
+  out += `0x${table[i].toString(16)}`;
+  out += i < table.length - 1 ? ', ' : '';
+  if (i % 16 === 15) out += '\n';
+}
+if (table.length % 16 !== 0) out += '\n';
+out += `};\n\n#endif\n`;
+
+const headerPath = join(root, 'src/common/parser/wasm/transition_table.h');
+writeFileSync(headerPath, out);
+console.info(`Wrote ${headerPath} (${table.length} entries)`);

bin/lint_changes.js

@@ -33,17 +33,47 @@ if (files.length === 0) {
 
 console.log(`Linting ${files.length} changed file(s)...`);
 
-const eslintArgs = ['--max-warnings', '0', '--no-warn-ignored'];
-if (fix) {
-  eslintArgs.push('--fix');
+const cwd = path.join(__dirname, '..');
+const isWin = process.platform === 'win32';
+
+/**
+ * @param {string} command
+ * @param {string[]} args
+ * @returns {Promise<void>}
+ */
+function run(command, args) {
+  return new Promise(/** @type {(resolve: () => void, reject: (reason: Error) => void) => void} */ ((resolve, reject) => {
+    const child = spawn(command, args, {
+      stdio: 'inherit',
+      cwd,
+      shell: isWin
+    });
+    child.on('close', code => {
+      if (code === 0) {
+        resolve();
+      } else {
+        reject(new Error(`${command} exited with code ${code}`));
+      }
+    });
+  }));
 }
-eslintArgs.push(...files);
 
-const eslint = process.platform === 'win32' ? 'eslint.cmd' : 'eslint';
-const child = spawn(eslint, eslintArgs, {
-  stdio: 'inherit',
-  cwd: path.join(__dirname, '..'),
-  shell: process.platform === 'win32'
+async function main() {
+  const oxlintArgs = ['--type-aware', '--max-warnings', '0'];
+  if (fix) {
+    oxlintArgs.push('--fix');
+  }
+  oxlintArgs.push(...files);
+
+  const oxlint = isWin ? 'oxlint.cmd' : 'oxlint';
+  await run(oxlint, oxlintArgs);
+
+  const eslintArgs = ['--config', 'eslint.config.naming.mjs', '--max-warnings', '0', ...files];
+  const eslint = isWin ? 'eslint.cmd' : 'eslint';
+  await run(eslint, eslintArgs);
+}
+
+main().catch(err => {
+  console.error(err.message);
+  process.exit(1);
 });
-
-child.on('close', code => process.exit(code ?? 0));

bin/setup-full.mjs

@@ -0,0 +1,138 @@
+// @ts-check
+
+import { cpSync, existsSync, lstatSync, readFileSync } from 'node:fs';
+import { spawnSync } from 'node:child_process';
+import { basename, dirname, resolve, sep } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const repoRoot = resolve(dirname(fileURLToPath(import.meta.url)), '../..');
+const nodeModulesPath = resolve(repoRoot, 'node_modules');
+const npmExecutable = process.platform === 'win32' ? 'npm.cmd' : 'npm';
+
+/** @typedef {{ folder: string; reason: string }} Candidate */
+
+/** @param {string} message */
+function log(message) {
+  console.info(`[setup-fast] ${message}`);
+}
+
+/** @param {string[]} args */
+function runNpm(args) {
+  log(`Running: npm ${args.join(' ')}`);
+  const result = spawnSync(npmExecutable, args, {
+    cwd: repoRoot,
+    stdio: 'inherit'
+  });
+  if (result.error) {
+    throw result.error;
+  }
+  if ((result.status ?? 1) !== 0) {
+    process.exit(result.status ?? 1);
+  }
+}
+
+/**
+ * @param {Candidate[]} candidates
+ * @param {string | undefined} folder
+ * @param {string} reason
+ */
+function addCandidate(candidates, folder, reason) {
+  if (!folder) {
+    return;
+  }
+  if (candidates.some(candidate => candidate.folder === folder)) {
+    return;
+  }
+  candidates.push({ folder, reason });
+  log(`Candidate found (${reason}): ${folder}`);
+}
+
+function detectMainSiblingFolder() {
+  const currentFolderName = basename(repoRoot);
+  if (!currentFolderName.startsWith('xterm.js') || currentFolderName === 'xterm.js') {
+    log(`Current folder is "${currentFolderName}", skipping xterm.js sibling lookup.`);
+    return undefined;
+  }
+  const siblingFolder = resolve(dirname(repoRoot), 'xterm.js');
+  log(`Current folder is "${currentFolderName}", sibling main folder candidate: ${siblingFolder}`);
+  return siblingFolder;
+}
+
+function detectWorktreeMainFolder() {
+  const gitPath = resolve(repoRoot, '.git');
+  if (!existsSync(gitPath)) {
+    log('No .git entry found at repo root.');
+    return undefined;
+  }
+  const gitStat = lstatSync(gitPath);
+  if (!gitStat.isFile()) {
+    log('.git is not a file, this repo does not appear to be a worktree checkout.');
+    return undefined;
+  }
+  const gitFileContent = readFileSync(gitPath, 'utf8').trim();
+  const gitDirMatch = /^gitdir:\s*(.+)$/m.exec(gitFileContent);
+  if (!gitDirMatch) {
+    log('Could not parse gitdir from .git file.');
+    return undefined;
+  }
+
+  const gitDirPath = resolve(repoRoot, gitDirMatch[1].trim());
+  log(`Parsed gitdir from .git file: ${gitDirPath}`);
+
+  const normalizedGitDirPath = gitDirPath.replace(/\\/g, '/');
+  const worktreeMarker = '/.git/worktrees/';
+  const markerIndex = normalizedGitDirPath.indexOf(worktreeMarker);
+  if (markerIndex === -1) {
+    log('gitdir path does not contain /.git/worktrees/, skipping worktree main folder lookup.');
+    return undefined;
+  }
+
+  const normalizedMainFolder = normalizedGitDirPath.slice(0, markerIndex);
+  const mainFolder = sep === '/' ? normalizedMainFolder : normalizedMainFolder.split('/').join(sep);
+  log(`Worktree main folder candidate: ${mainFolder}`);
+  return mainFolder;
+}
+
+function resolveSourceFolder() {
+  /** @type {Candidate[]} */
+  const candidates = [];
+  addCandidate(candidates, detectMainSiblingFolder(), 'xterm.js sibling');
+  addCandidate(candidates, detectWorktreeMainFolder(), 'worktree main repo');
+
+  for (const candidate of candidates) {
+    const candidateNodeModulesPath = resolve(candidate.folder, 'node_modules');
+    if (existsSync(candidateNodeModulesPath)) {
+      log(`Using candidate (${candidate.reason}) with node_modules: ${candidate.folder}`);
+      return candidate.folder;
+    }
+    log(`Candidate skipped (${candidate.reason}), node_modules missing: ${candidateNodeModulesPath}`);
+  }
+
+  log('No candidate folder with node_modules was found.');
+  return undefined;
+}
+
+if (!existsSync(nodeModulesPath)) {
+  log(`node_modules missing: ${nodeModulesPath}`);
+  const sourceFolder = resolveSourceFolder();
+  if (sourceFolder) {
+    const sourceNodeModulesPath = resolve(sourceFolder, 'node_modules');
+    log(`Copying node_modules from ${sourceNodeModulesPath} to ${nodeModulesPath}`);
+    try {
+      cpSync(sourceNodeModulesPath, nodeModulesPath, { recursive: true });
+      log('node_modules copy completed.');
+    } catch (error) {
+      const message = error instanceof Error ? error.message : String(error);
+      log(`node_modules copy failed: ${message}`);
+      log('Falling back to npm ci.');
+      runNpm(['ci']);
+    }
+  } else {
+    log('No source folder available, running npm ci.');
+    runNpm(['ci']);
+  }
+} else {
+  log(`node_modules already exists: ${nodeModulesPath}`);
+}
+
+runNpm(['run', 'setup']);

bin/test_unit.js

@@ -8,7 +8,7 @@ const path = require('path');
 
 const COVERAGE_LINES_THRESHOLD = 40;
 
-// Add `out` to the NODE_PATH so absolute paths can be resolved.
+// Add `out-esbuild` to NODE_PATH so addon path-mapped imports (common/*, browser/*) resolve.
 const env = { ...process.env };
 env.NODE_PATH = path.resolve(__dirname, '../out-esbuild');