refactor(ui): split mounted diff row views

.changeset/quiet-row-facade.md

@@ -0,0 +1,2 @@
+---
+---

.changeset/tidy-mounted-rows.md

@@ -0,0 +1,2 @@
+---
+---

docs/browser-review-seam-audit.md

@@ -109,13 +109,13 @@ whether a client needs more than that is Phase 5's first question.
   _Repaid (Phase 1 PR 2, model side)_: `splitLineCount`/`unifiedLineCount` carried on
   `ReviewFileV1` by `core/review/document.ts`; the browser consumes them in Phase 5.
 - **A8. Empty-diff explanation — 3 variants with different precedence.** Terminal
-  `renderRows.tsx` `diffMessage` (rename-pure first), web `ReviewStream.tsx` (binary first),
+  `plannedRowText.ts` `diffMessage` (rename-pure first), web `ReviewStream.tsx` (binary first),
   `staticDiffPager.ts` (extra cases). Same file can explain itself differently per client.
   Fix: `reviewEmptyDiffReason(file)` in core.
   _Repaid (Phase 1 PR 2)_: `reviewEmptyDiffReason` in `core/review/document.ts` with one canonical
   precedence — what the change _is_ outranks how it is stored (`rename-only` -> `binary` ->
   `too-large` -> `new-file` -> `deleted-file` -> `no-hunks`), the review stream's existing order.
-  `renderRows.tsx` and `staticDiffPager.ts` keep their own wording and share the reason; fixture
+  `plannedRowText.ts` and `staticDiffPager.ts` keep their own wording and share the reason; fixture
   `binary-rename-with-no-rows`. The static pager's own order put storage first, so a renamed
   binary or oversized rename now reports as a rename there too.
 - **A9. STML tag vocabulary — parse shared, tag semantics forked.** Terminal

docs/extension-architecture.md

@@ -128,10 +128,13 @@ clusters, with context and gap lines sharing one range list under both side
 keys — and the one span transform that repaints backgrounds without changing
 text. `src/ui/diff/rowStyle.ts` resolves tones against the actual line
 background with the word-diff minimum-contrast guarantee.
-`src/ui/diff/renderRows.tsx` applies the transform per rendered cell, which
-keeps highlights out of `buildDiffSectionRowPlan`, its caches, and every
-geometry measurement: a highlight change is a repaint, never a re-plan. The
-static pager never runs extension code, so highlights are interactive-only.
+`src/ui/diff/CodeRowView.tsx` applies the transform through the cell painter,
+which keeps highlights out of `buildDiffSectionRowPlan`, its caches, and every
+geometry measurement: a highlight change is a repaint, never a re-plan.
+`src/ui/diff/DiffRowView.tsx` remains only the memoized dispatch facade; raw-row
+adaptation there supports the public OpenTUI and extension current-line surfaces, while
+`src/ui/diff/cursorHighlight.ts` owns stable-key cursor matching. The static pager never
+runs extension code, so highlights are interactive-only.
 
 Agent attention marks (`hunk session highlight add` / `clear`) join this same
 pipeline rather than growing a second one: `useTerminalReview.ts` validates

src/opentui/HunkDiffBody.tsx

@@ -3,7 +3,7 @@ import { DEFAULT_TAB_WIDTH } from "../core/run/tabWidth";
 import { findMaxLineNumber } from "../ui/diff/codeColumns";
 import { buildSplitRows, buildStackRows } from "../ui/diff/diffRows";
 import { diffMessage, fitText } from "../ui/diff/plannedRowText";
-import { DiffRowView } from "../ui/diff/renderRows";
+import { DiffRowView } from "../ui/diff/DiffRowView";
 import { useHighlightedDiff } from "../ui/diff/useHighlightedDiff";
 import { resolveTheme } from "../ui/themes";
 import { toInternalDiffFile } from "./model";

src/ui/components/panes/DiffPane.tsx

@@ -27,7 +27,8 @@ import {
 } from "../../../core/review/state";
 import type { FileSourceStatus } from "../../diff/expandCollapsedRows";
 import type { ActiveAddNoteAffordance } from "../../diff/DiffSectionBody";
-import { isNestedRowMouseAction, type CursorHighlight } from "../../diff/renderRows";
+import type { CursorHighlight } from "../../diff/cursorHighlight";
+import { isNestedRowMouseAction } from "../../diff/rowMouseActions";
 import type { DraftReviewNote } from "../../lib/reviewNoteMapping";
 import {
   createVisibleAgentNote,

src/ui/components/panes/DiffSection.tsx

@@ -4,7 +4,7 @@ import type { LayoutMode } from "../../../core/run/commandInputs";
 import type { UserNoteLineTarget } from "../../../core/liveComments";
 import type { FileSourceStatus } from "../../diff/expandCollapsedRows";
 import { DiffSectionBody, type ActiveAddNoteAffordance } from "../../diff/DiffSectionBody";
-import type { CursorHighlight } from "../../diff/renderRows";
+import type { CursorHighlight } from "../../diff/cursorHighlight";
 import type { VisibleBodyBounds } from "../../diff/rowWindowing";
 import type { DiffSectionGeometry } from "../../diff/diffSectionGeometry";
 import type { DiffSectionRowPlan } from "../../diff/diffSectionRowPlan";

src/ui/components/panes/FileView.tsx

@@ -9,7 +9,7 @@ import type {
 } from "../../../extension-api/types";
 import type { AppTheme } from "../../themes";
 import type { DiffSectionGeometry } from "../../diff/diffSectionGeometry";
-import { plannedRowMatchesCursor, type CursorHighlight } from "../../diff/renderRows";
+import { plannedRowMatchesCursor, type CursorHighlight } from "../../diff/cursorHighlight";
 import { cursorLineHighlightBg } from "../../diff/rowStyle";
 import { resolveVisibleRowIndexWindow, type VisibleBodyBounds } from "../../diff/rowWindowing";
 import { reviewRowId } from "../../lib/ids";

src/ui/components/ui-components.test.tsx

@@ -36,7 +36,7 @@ const { DiffFileHeaderRow } = await import("./panes/DiffFileHeaderRow");
 const { DiffSectionBody } = await import("../diff/DiffSectionBody");
 const { measurePlannedRenderedRowHeight, measureRenderedRowHeight } =
   await import("../diff/codeRowLayout");
-const { DiffRowView } = await import("../diff/renderRows");
+const { DiffRowView } = await import("../diff/DiffRowView");
 
 function createTestDiffFile(
   id: string,

src/ui/diff/CodeCellView.test.tsx

@@ -11,7 +11,7 @@ import {
 import { legacyPlannedDiffRow, planCodeRowLayout } from "./codeRowLayout";
 import type { DiffRow } from "./diffRows";
 import { lineHighlightPaintKey, type LineHighlightPaintIndex } from "./lineHighlightPaint";
-import { DiffRowView } from "./renderRows";
+import { DiffRowView } from "./DiffRowView";
 import { resolveTheme, withTransparentSurfaces } from "../themes";
 
 /** Capture one code-row component and always release its OpenTUI renderer. */

src/ui/diff/CodeRowView.test.tsx

@@ -0,0 +1,71 @@
+import { expect, test } from "bun:test";
+import { testRender } from "@opentui/react/test-utils";
+import { act } from "react";
+import { capturedTestColorToHex } from "../../../test/helpers/test-color-helpers";
+import { resolveTheme } from "../themes";
+import { CodeRowView, type PlannedCodeReviewRow } from "./CodeRowView";
+import { cursorLineHighlightBg, selectionHighlightBg, stackCellPalette } from "./rowStyle";
+
+/** Return the normalized background painted behind matching captured text. */
+function backgroundForText(
+  capture: ReturnType<Awaited<ReturnType<typeof testRender>>["captureSpans"]>,
+  text: string,
+) {
+  const span = capture.lines
+    .flatMap((line) => line.spans)
+    .find((candidate) => candidate.text.includes(text));
+  return capturedTestColorToHex(span?.bg)?.toLowerCase();
+}
+
+test("CodeRowView gives copy selection precedence over cursor paint", async () => {
+  const theme = resolveTheme("github-dark-default", null);
+  const plannedRow: PlannedCodeReviewRow = {
+    kind: "diff-row",
+    key: "diff-row:precedence",
+    stableKey: "line:0:new:1",
+    fileId: "paint",
+    hunkIndex: 0,
+    row: {
+      type: "stack-line",
+      key: "precedence",
+      fileId: "paint",
+      hunkIndex: 0,
+      cell: {
+        kind: "addition",
+        sign: "+",
+        newLineNumber: 1,
+        spans: [{ text: "selected" }],
+      },
+    },
+  };
+  const setup = await testRender(
+    <CodeRowView
+      plannedRow={plannedRow}
+      width={16}
+      lineNumberDigits={1}
+      showLineNumbers={false}
+      wrapLines={false}
+      codeHorizontalOffset={0}
+      theme={theme}
+      selected={false}
+      copySelectedRowRange={{ startCol: 0, endCol: Number.MAX_SAFE_INTEGER }}
+      cursorHighlight={{ stableKey: plannedRow.stableKey, side: "new", style: "row" }}
+    />,
+    { width: 20, height: 2 },
+  );
+
+  try {
+    await act(async () => {
+      await setup.renderOnce();
+    });
+    const background = backgroundForText(setup.captureSpans(), "selected");
+    const baseBackground = stackCellPalette("addition", theme).contentBg;
+
+    expect(background).toBe(selectionHighlightBg(baseBackground, theme).toLowerCase());
+    expect(background).not.toBe(cursorLineHighlightBg(baseBackground, theme).toLowerCase());
+  } finally {
+    await act(async () => {
+      setup.renderer.destroy();
+    });
+  }
+});