Commit 50027bb3ad2912f9127304392a2c85ad5ab9a4ba | the-knife

author	Julius Marminge <julius0216@outlook.com> 2026-09-05 00:15:36-07:00
committer	GitHub <noreply@github.com> 2026-09-05 00:15:36-07:00
log	50027bb3ad2912f9127304392a2c85ad5ab9a4ba
tree	4cf4b0444d0a6ff7cb23a276fee7469f99e0c6ce
parent	3e1333319aacff96856a3c161b8787ff6b0ddd6b
signature	Signed by PGP key B5690EEEBB952194

fix(mobile): keep highlighting review diffs after a long line (#9911)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

2 files changed, 38 insertions(+), 15 deletions(-)

apps
- mobile
  - src
    features
    diffs
    nativeReviewDiffHighlighter.test.ts
    nativeReviewDiffHighlighter.ts

apps/mobile/src/features/diffs/nativeReviewDiffHighlighter.test.ts+29-7

 @@ -257,13 +257,13 @@ describe.each(["native", "javascript"] as const)("%s highlighting budgets", (eng
     expect(result.tokensByRowId["line-1"]?.some((token) => token.color !== null)).toBe(true);
   });
-  it("keeps long lines and unknown following syntax plain until the next hunk", async () => {
+  it("keeps only the long line plain and resumes highlighting after it", async () => {
     const longLine = `${"x".repeat(1_001)} /*`;
     const rows = [
       line(1, "export const before = 1;"),
       line(2, longLine),
       { kind: "comment", id: "note", commentText: "Check this", fileId: TYPESCRIPT_FILE.id },
-      line(3, "inside the comment */"),
+      line(3, "export const inside = 'x';"),
       makeHunk("next-hunk"),
       line(100, "export const after = 2;"),
     ] satisfies ReadonlyArray<NativeReviewDiffRow>;
 @@ -274,14 +274,36 @@ describe.each(["native", "javascript"] as const)("%s highlighting budgets", (eng
     expect(result.tokensByRowId["line-2"]).toEqual([
       { content: longLine, color: null, fontStyle: null },
     ]);
-    expect(result.tokensByRowId["line-3"]).toEqual([
+    for (const id of ["line-1", "line-3", "line-100"]) {
-      { content: "inside the comment */", color: null, fontStyle: null },
+      expect(result.tokensByRowId[id]?.some((token) => token.color !== null)).toBe(true);
-    ]);
+    }
-    expect(result.tokensByRowId["line-1"]?.some((token) => token.color !== null)).toBe(true);
-    expect(result.tokensByRowId["line-100"]?.some((token) => token.color !== null)).toBe(true);
     expect(tokenization.calls.some((code) => code.includes(longLine))).toBe(false);
   });
+  it("highlights the rows after a long line the same regardless of the first window", async () => {
+    const rows = [
+      line(1, "export const before = 1;"),
+      line(2, `const data = "${"x".repeat(1_050)}";`),
+      line(3, "export const inside = 'x';"),
+      line(4, "export const after = 2;"),
+    ];
+    const spanning = await highlightRows(rows);
+    const afterLongLine = await highlightNativeReviewDiffVisibleRows({
+      rows,
+      files: [TYPESCRIPT_FILE],
+      scheme: "dark",
+      engine,
+      firstRowIndex: 2,
+      lastRowIndex: 3,
+      overscanRows: 0,
+    });
+    for (const id of ["line-3", "line-4"]) {
+      expect(spanning.tokensByRowId[id]?.some((token) => token.color !== null)).toBe(true);
+      expect(afterLongLine.tokensByRowId[id]).toEqual(spanning.tokensByRowId[id]);
+    }
+  });
   it("preserves multiline grammar and row mapping across character-limited batches", async () => {
     const opening = line(1, "const message = `open");
     const body = Array.from({ length: 40 }, (_, index) => line(index + 2, "inside ".repeat(45)));

apps/mobile/src/features/diffs/nativeReviewDiffHighlighter.ts+9-8

 @@ -247,15 +247,16 @@ function createHighlighterHandle(
       while (start < lines.length) {
         if (signal?.aborted) return [];
-        // Skipping this line leaves its ending grammar state unknown. Keep the
+        // Skipping this line leaves its ending grammar state unknown. Resume
-        // rest of this contiguous segment plain instead of guessing its syntax.
+        // from a fresh state rather than leaving the rest of the segment plain:
+        // highlighted rows are cached for the sheet's lifetime, so a plain tail
+        // would stick, and which rows it covered would depend on where the
+        // first visible window happened to start.
         if (lines[start]!.length > NATIVE_REVIEW_DIFF_TOKENIZE_MAX_LINE_LENGTH) {
-          highlighted.push(
+          highlighted.push([{ content: lines[start] || " ", color: null, fontStyle: null }]);
-            ...lines
+          grammarState = undefined;
-              .slice(start)
+          start += 1;
-              .map((content) => [{ content: content || " ", color: null, fontStyle: null }]),
+          continue;
-          );
-          break;
         }
         let end = start;