Keep tour steps and code peeks clipped to their pinned lines

apps/review-desktop/code-oss/src/vs/review/common/reviewLens.test.ts

@@ -1,7 +1,7 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import { lensContextGaps } from './reviewLens.js';
-import type { IDocumentDiff } from '../../editor/common/diff/documentDiffProvider.js';
+import type { IDocumentContextGap, IDocumentDiff } from '../../editor/common/diff/documentDiffProvider.js';
 
 const plain: IDocumentDiff = { changes: [], moves: [], identical: false, quitEarly: false };
 test('a lens keeps disjoint attachments and hides the intervening code', () => {
@@ -34,6 +34,49 @@ test('a clipped outer fold leaves its nested fold usable in a code peek', () =>
 	assert.deepEqual(whole.filter(gap => gap.foldStateId).map(gap => gap.foldStateId), [1]);
 });
 
+// The head lines left on screen, as [from, to] runs.
+const shownLines = (gaps: readonly IDocumentContextGap[], lineCount: number) => {
+	const runs: [number, number][] = [];
+	for (let line = 1; line <= lineCount; line++) {
+		if (gaps.some(gap => gap.collapsed !== false && line >= gap.modifiedStart && line < gap.modifiedStart + gap.modifiedCount)) continue;
+		const last = runs.at(-1);
+		if (last && last[1] === line - 1) last[1] = line;
+		else runs.push([line, line]);
+	}
+	return runs;
+};
+const head = (fromLine: number, toLine: number) => [{ side: 'head' as const, file: 'a.ts', fromLine, toLine }];
+
+test('in an added file a lens shows the first and last lines of its enclosing scopes, not the whole file', () => {
+	// A 30-line added file: a class on lines 3-25 with a method on lines 10-18. Nothing is collapsed.
+	const added: IDocumentDiff = {
+		...plain,
+		sourceLineAlignment: Array.from({ length: 30 }, (_, i) => [null, i] as const),
+		contextScopes: { original: [], modified: [[2, 25], [9, 18]] },
+	};
+	assert.deepEqual(shownLines(lensContextGaps(added, 0, 30, head(13, 14)), 30), [[3, 3], [10, 18], [25, 25]]);
+	// The same, with a function on lines 27-29 folded.
+	const folded: IDocumentDiff = {
+		...added,
+		contextScopes: { original: [], modified: [[2, 25], [9, 18], [26, 29]] },
+		contextGaps: [{ originalStart: 1, originalCount: 0, modifiedStart: 27, modifiedCount: 3, collapsed: true }],
+	};
+	assert.deepEqual(shownLines(lensContextGaps(folded, 0, 30, head(13, 14)), 30), [[3, 3], [10, 18], [25, 25]]);
+});
+
+test('in a modified file a lens shows the whole run between collapsed bands', () => {
+	// A function on lines 5-20, with the code before and after it collapsed.
+	const modified: IDocumentDiff = {
+		...plain,
+		contextScopes: { original: [[4, 20]], modified: [[4, 20]] },
+		contextGaps: [
+			{ originalStart: 1, originalCount: 4, modifiedStart: 1, modifiedCount: 4, collapsed: true },
+			{ originalStart: 21, originalCount: 10, modifiedStart: 21, modifiedCount: 10, collapsed: true },
+		],
+	};
+	assert.deepEqual(shownLines(lensContextGaps(modified, 30, 30, head(15, 15)), 30), [[5, 20]]);
+});
+
 test('viewed folds never hide an unread counterpart, and do not overlap structural folds', async () => {
 	const { viewedContextGaps } = await import('./reviewLens.js');
 	const range = (side: 'base' | 'head', fromLine: number, toLine: number) => ({ side, file: 'a.ts', fromLine, toLine });

apps/review-desktop/code-oss/src/vs/review/common/reviewLens.ts

@@ -35,7 +35,10 @@ export function lensContextGaps(diff: IDocumentDiff, originalCount: number, modi
 			if (!open[start]) { start++; continue; }
 			let end = start + 1;
 			while (end < rows.length && open[end]) end++;
-			if (seeds.slice(start, end).some(Boolean)) context.fill(true, start, end);
+			// diffr never collapses inside added code, so no band bounds a run of
+			// only added lines (as in an added file). Keep only its seeds.
+			if (rows.slice(start, end).every(row => row[0] === null)) for (let index = start; index < end; index++) context[index] ||= seeds[index];
+			else if (seeds.slice(start, end).some(Boolean)) context.fill(true, start, end);
 			start = end;
 		}
 	}