fix: preserve snapshot indentation in diff formatter

Author: thymikee

src/__tests__/cli-diff.test.ts

@@ -76,9 +76,9 @@ test('diff snapshot renders human-readable unified diff text', async () => {
   const result = await runCliCapture(['diff', 'snapshot']);
   assert.equal(result.code, null);
   assert.equal(result.calls.length, 1);
-  assert.match(result.stdout, /^  @e2 \[window\]/m);
-  assert.match(result.stdout, /^- @e3 \[text\] "67"$/m);
-  assert.match(result.stdout, /^\+ @e3 \[text\] "134"$/m);
+  assert.match(result.stdout, /^@e2 \[window\]/m);
+  assert.match(result.stdout, /^-  @e3 \[text\] "67"$/m);
+  assert.match(result.stdout, /^\+  @e3 \[text\] "134"$/m);
   assert.match(result.stdout, /1 additions, 1 removals, 1 unchanged/);
   assert.equal(result.stderr, '');
 });

src/utils/__tests__/output.test.ts

@@ -19,9 +19,9 @@ test('formatSnapshotDiffText renders unified diff lines with summary', () => {
   });
 
   assert.doesNotMatch(text, /^@e0 \[application\]$/m);
-  assert.match(text, /^  @e2 \[window\]/m);
-  assert.match(text, /^- @e3 \[other\] "67"$/m);
-  assert.match(text, /^\+ @e3 \[other\] "134"$/m);
+  assert.match(text, /^@e2 \[window\]/m);
+  assert.match(text, /^-  @e3 \[other\] "67"$/m);
+  assert.match(text, /^\+  @e3 \[other\] "134"$/m);
   assert.match(text, /^  @e5 \[button\] "Increment"$/m);
   assert.doesNotMatch(text, /^  @e6 \[text\] "Footer"$/m);
   assert.match(text, /2 additions, 2 removals, 4 unchanged/);

src/utils/output.ts

@@ -87,9 +87,9 @@ export function formatSnapshotDiffText(data: Record<string, unknown>): string {
   const contextLines = applyContextWindow(rawLines, 1);
   const lines = contextLines.map((line) => {
     const text = typeof line.text === 'string' ? line.text : '';
-    if (line.kind === 'added') return `+ ${text.trimStart()}`;
-    if (line.kind === 'removed') return `- ${text.trimStart()}`;
-    return `  ${text.trimStart()}`;
+    if (line.kind === 'added') return text.startsWith(' ') ? `+${text}` : `+ ${text}`;
+    if (line.kind === 'removed') return text.startsWith(' ') ? `-${text}` : `- ${text}`;
+    return text;
   });
   const body = lines.length > 0 ? `${lines.join('\n')}\n` : '';
   return `${body}${additions} additions, ${removals} removals, ${unchanged} unchanged\n`;