fix(native-chat): render structured patches as diffs

src/renderer/src/components/native-chat/NativeChatToolRun.test.tsx

@@ -24,4 +24,28 @@ describe('NativeChatToolRun', () => {
     expect(screen.getByTitle('src/index.ts')).toHaveTextContent('src/index.ts')
     expect(screen.queryByTitle('{"file_path":"src/index.ts","offset":10}')).toBeNull()
   })
+
+  it('renders structured apply_patch changes as a reviewable diff instead of JSON', () => {
+    const blocks: NativeChatBlock[] = [
+      {
+        type: 'tool-call',
+        name: 'apply_patch',
+        input: {
+          changes: [
+            {
+              path: '/repo/src/app.ts',
+              kind: { type: 'update', move_path: null },
+              diff: '@@ -1 +1 @@\n-before\n+after'
+            }
+          ]
+        }
+      }
+    ]
+
+    const { container } = render(<NativeChatToolRun blocks={blocks} expandSignal />)
+
+    expect(screen.getByText('+after')).toBeInTheDocument()
+    expect(screen.getByText('-before')).toBeInTheDocument()
+    expect(container.querySelector('pre')).toBeNull()
+  })
 })

src/renderer/src/components/native-chat/native-chat-diff.test.ts

@@ -30,6 +30,39 @@ describe('diffFromToolCall', () => {
     ])
   })
 
+  it('reads structured apply_patch file changes as a diff', () => {
+    const diff = diffFromToolCall('apply_patch', {
+      changes: [
+        {
+          path: '/repo/src/app.ts',
+          kind: { type: 'update', move_path: null },
+          diff: '@@ -1,2 +1,2 @@\n const value = 1\n-old()\n+newValue()'
+        }
+      ]
+    })
+
+    expect(diff).toEqual([
+      { kind: 'meta', text: '--- /repo/src/app.ts' },
+      { kind: 'meta', text: '+++ /repo/src/app.ts' },
+      { kind: 'meta', text: '@@ -1,2 +1,2 @@' },
+      { kind: 'context', text: ' const value = 1' },
+      { kind: 'del', text: 'old()' },
+      { kind: 'add', text: 'newValue()' }
+    ])
+  })
+
+  it('reads direct apply_patch text as a diff', () => {
+    expect(
+      diffFromToolCall('apply_patch', {
+        patch: '@@ -1 +1 @@\n-before\n+after'
+      })
+    ).toEqual([
+      { kind: 'meta', text: '@@ -1 +1 @@' },
+      { kind: 'del', text: 'before' },
+      { kind: 'add', text: 'after' }
+    ])
+  })
+
   it('returns null when there is no old/new payload', () => {
     expect(diffFromToolCall('Edit', { file_path: '/x' })).toBeNull()
   })

src/shared/native-chat-diff.ts

@@ -80,6 +80,35 @@ function toLines(value: unknown, maxLines: number): { lines: string[]; truncated
   return { lines: bounded, truncated }
 }
 
+function patchTextFromToolInput(value: Record<string, unknown>): string | null {
+  if (typeof value.patch === 'string') {
+    return value.patch
+  }
+  if (typeof value.diff === 'string') {
+    return value.diff
+  }
+  if (!Array.isArray(value.changes)) {
+    return null
+  }
+  const sections = value.changes.flatMap((entry) => {
+    if (typeof entry !== 'object' || entry === null) {
+      return []
+    }
+    const change = entry as Record<string, unknown>
+    if (typeof change.diff !== 'string') {
+      return []
+    }
+    const path = typeof change.path === 'string' ? change.path : 'file'
+    const kind =
+      typeof change.kind === 'object' && change.kind !== null
+        ? (change.kind as Record<string, unknown>)
+        : null
+    const nextPath = kind && typeof kind.move_path === 'string' ? kind.move_path : path
+    return [`--- ${path}\n+++ ${nextPath}\n${change.diff}`]
+  })
+  return sections.length > 0 ? sections.join('\n') : null
+}
+
 export function diffFromToolCall(
   name: string,
   input: unknown,
@@ -89,6 +118,10 @@ export function diffFromToolCall(
     return null
   }
   const value = input as Record<string, unknown>
+  const patchText = patchTextFromToolInput(value)
+  if (patchText !== null) {
+    return diffFromText(patchText, maxLines)
+  }
   const oldLines = toLines(value.old_string ?? value.oldString ?? value.old, maxLines)
   const newLines = toLines(
     value.new_string ?? value.newString ?? value.new ?? value.content ?? value.file_text,