Add canvas-specific intake validation for external plugins (#2319)

* Add canvas-aware checks to external plugin intake

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Copilot-Session: 0f03fd92-3bfa-4c67-a709-177fbd46c40e

* Potential fix for pull request finding

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

.github/ISSUE_TEMPLATE/external-plugin.yml

@@ -15,6 +15,8 @@ body:
         - Public submissions are **GitHub-only** in v1.
         - The plugin must live in a **public GitHub repository**.
         - Provide an immutable **ref**, **sha**, or both for review.
+        - If your plugin includes a canvas extension, include the **canvas** keyword.
+        - Canvas plugins are validated for `logo: "assets/preview.png"` using the submitted immutable **sha** or **ref**.
         - Do **not** open a PR that edits `plugins/external.json` directly.
   - type: input
     id: plugin-name
@@ -106,7 +108,7 @@ body:
     id: keywords
     attributes:
       label: Keywords
-      description: Comma-separated or newline-separated lowercase tags.
+      description: Comma-separated or newline-separated lowercase tags. Include `canvas` if the plugin contains a canvas extension.
       placeholder: |
         automation
         github

.github/workflows/external-plugin-command-router.yml

@@ -559,7 +559,11 @@ jobs:
               owner: context.repo.owner,
               repo: context.repo.repo,
               issueNumber: context.issue.number,
-              desiredLabels: new Set(['external-plugin', 'ready-for-review'])
+              desiredLabels: new Set([
+                'external-plugin',
+                'ready-for-review',
+                ...(labelNames.has('external-plugin-canvas') ? ['external-plugin-canvas'] : [])
+              ])
             });
 
             const marker = '<!-- external-plugin-mark-ready-override -->';

.github/workflows/setup-labels.yml

@@ -44,6 +44,10 @@ jobs:
                 color: 'FEF2C0',
                 description: 'Public external plugin submission'
               },
+              'external-plugin-canvas': {
+                color: '1D76DB',
+                description: 'External plugin submission includes a canvas extension'
+              },
               'hooks': {
                 color: 'C2E0C6',
                 description: 'PR touches hooks'