diff --git a/addons/addon-search/src/SearchEngine.test.ts b/addons/addon-search/src/SearchEngine.test.ts
index b0054bd94..2c5cc9543 100644
--- a/addons/addon-search/src/SearchEngine.test.ts
+++ b/addons/addon-search/src/SearchEngine.test.ts
@@ -256,6 +256,12 @@ describe('SearchEngine', () => {
 
         assert.strictEqual(searchEngine.find('.*?', 0, 0, { regex: true }), undefined); // Empty matches should be ignored
       });
+
+      it('should ignore empty regex matches when searching backwards', async () => {
+        await writeP(terminal, 'Hello World');
+
+        assert.strictEqual(searchEngine.findPreviousWithSelection('.*?', { regex: true }), undefined);
+      });
     });
 
     describe('combined options', () => {
diff --git a/addons/addon-search/src/SearchLineCache.test.ts b/addons/addon-search/src/SearchLineCache.test.ts
index 77f64c81e..c8a39f49b 100644
--- a/addons/addon-search/src/SearchLineCache.test.ts
+++ b/addons/addon-search/src/SearchLineCache.test.ts
@@ -244,6 +244,17 @@ describe('SearchLineCache', () => {
       assert.equal(retrieved![1].length, 4);
     });
 
+    it('should lazily cache lowercased line text via SearchEngine usage', async () => {
+      await writeP(terminal, 'Hello WORLD');
+      cache.initLinesCache();
+      const entry = cache.translateBufferLineToStringWithWrap(0, true);
+      cache.setLineInCache(0, entry);
+      assert.equal(entry[2], undefined);
+      entry[2] = entry[0].toLowerCase();
+      cache.setLineInCache(0, entry);
+      assert.strictEqual(cache.getLineFromCache(0)?.[2], 'hello world');
+    });
+
     it('should handle unicode characters in cache entries', () => {
       const entry: LineCacheEntry = [
         'Hello 世界 🌍 测试',
diff --git a/addons/addon-search/src/SearchResultTracker.test.ts b/addons/addon-search/src/SearchResultTracker.test.ts
new file mode 100644
index 000000000..8f9d1822c
--- /dev/null
+++ b/addons/addon-search/src/SearchResultTracker.test.ts
@@ -0,0 +1,53 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+import { assert } from 'chai';
+import { SearchResultTracker } from './SearchResultTracker';
+import type { ISearchResult } from './SearchEngine';
+
+describe('SearchResultTracker', () => {
+  let tracker: SearchResultTracker;
+
+  beforeEach(() => {
+    tracker = new SearchResultTracker();
+  });
+
+  afterEach(() => {
+    tracker.dispose();
+  });
+
+  describe('updateResults', () => {
+    it('should store results without copying when within limit', () => {
+      const results: ISearchResult[] = [{ term: 'a', row: 0, col: 0, size: 1 }];
+      tracker.updateResults(results, 10);
+      assert.strictEqual(tracker.searchResults, results);
+    });
+  });
+
+  describe('findResultIndex', () => {
+    it('should return the index of a tracked result', () => {
+      const results: ISearchResult[] = [
+        { term: 'a', row: 0, col: 0, size: 1 },
+        { term: 'b', row: 0, col: 2, size: 1 }
+      ];
+      tracker.updateResults(results, 10);
+      assert.strictEqual(tracker.findResultIndex(results[1]), 1);
+    });
+
+    it('should return -1 when the result is not tracked', () => {
+      tracker.updateResults([{ term: 'a', row: 0, col: 0, size: 1 }], 10);
+      assert.strictEqual(tracker.findResultIndex({ term: 'z', row: 1, col: 0, size: 1 }), -1);
+    });
+  });
+
+  describe('fireResultsChanged', () => {
+    it('should not fire when decorations are disabled', () => {
+      let fired = false;
+      tracker.onDidChangeResults(() => fired = true);
+      tracker.updateResults([{ term: 'a', row: 0, col: 0, size: 1 }], 10);
+      tracker.fireResultsChanged(false);
+      assert.strictEqual(fired, false);
+    });
+  });
+});
diff --git a/addons/addon-search/src/SearchState.test.ts b/addons/addon-search/src/SearchState.test.ts
new file mode 100644
index 000000000..974c4b491
--- /dev/null
+++ b/addons/addon-search/src/SearchState.test.ts
@@ -0,0 +1,61 @@
+/**
+ * Copyright (c) 2026 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+import { assert } from 'chai';
+import { SearchState } from './SearchState';
+import type { ISearchOptions } from '@xterm/addon-search';
+
+const DECORATIONS_A: ISearchOptions = {
+  decorations: {
+    activeMatchColorOverviewRuler: '#ff0000',
+    matchOverviewRuler: '#00ffff'
+  }
+};
+
+const DECORATIONS_B: ISearchOptions = {
+  decorations: {
+    activeMatchColorOverviewRuler: '#00ff00',
+    matchOverviewRuler: '#00ffff'
+  }
+};
+
+describe('SearchState', () => {
+  let state: SearchState;
+
+  beforeEach(() => {
+    state = new SearchState();
+  });
+
+  describe('didOptionsChange', () => {
+    it('should detect caseSensitive changes', () => {
+      state.lastSearchOptions = { caseSensitive: false };
+      assert.strictEqual(state.didOptionsChange({ caseSensitive: true }), true);
+    });
+
+    it('should detect decoration option changes', () => {
+      state.lastSearchOptions = DECORATIONS_A;
+      assert.strictEqual(state.didOptionsChange(DECORATIONS_B), true);
+    });
+
+    it('should return false when semantic options are unchanged', () => {
+      const options: ISearchOptions = { caseSensitive: false, regex: false, wholeWord: false };
+      state.lastSearchOptions = options;
+      assert.strictEqual(state.didOptionsChange({ caseSensitive: false, regex: false, wholeWord: false }), false);
+    });
+  });
+
+  describe('shouldUpdateHighlighting', () => {
+    it('should update when options change for the same term', () => {
+      state.cachedSearchTerm = 'test';
+      state.lastSearchOptions = { caseSensitive: false, decorations: DECORATIONS_A.decorations };
+      assert.strictEqual(state.shouldUpdateHighlighting('test', { caseSensitive: true, decorations: DECORATIONS_A.decorations }), true);
+    });
+
+    it('should not update without decorations', () => {
+      state.cachedSearchTerm = 'test';
+      state.lastSearchOptions = { caseSensitive: false };
+      assert.strictEqual(state.shouldUpdateHighlighting('test', { caseSensitive: true }), false);
+    });
+  });
+});