fix(daemon): Avoid replaying truncated session diffs

packages/cli/src/acp-integration/session/emitters/ToolCallEmitter.test.ts

@@ -231,6 +231,11 @@ describe('ToolCallEmitter', () => {
           _meta: { toolName: 'edit_file', provenance: 'builtin' },
         }),
       );
+      expect(sendUpdateSpy.mock.calls[0][0].rawOutput).toEqual({
+        fileName: '/test/file.ts',
+        originalContent: 'old content',
+        newContent: 'new content',
+      });
     });
 
     it('should not replay truncated session previews as full diffs', async () => {
@@ -266,6 +271,7 @@ describe('ToolCallEmitter', () => {
           _meta: { toolName: 'edit_file', provenance: 'builtin' },
         }),
       );
+      expect(sendUpdateSpy.mock.calls[0][0].rawOutput).toBeUndefined();
     });
 
     it('should transform message parts to content', async () => {

packages/cli/src/acp-integration/session/emitters/ToolCallEmitter.ts

@@ -171,7 +171,10 @@ export class ToolCallEmitter extends BaseEmitter {
     };
 
     // Add rawOutput from resultDisplay
-    if (params.resultDisplay !== undefined) {
+    if (
+      params.resultDisplay !== undefined &&
+      !this.isTruncatedSessionDiffDisplay(params.resultDisplay)
+    ) {
       (update as Record<string, unknown>)['rawOutput'] = params.resultDisplay;
     }
 
@@ -353,7 +356,7 @@ export class ToolCallEmitter extends BaseEmitter {
 
     // Check if this is a diff display (edit tool result)
     if ('fileName' in obj && 'newContent' in obj) {
-      if (obj['truncatedForSession'] === true) {
+      if (this.isTruncatedSessionDiffDisplay(resultDisplay)) {
         return {
           type: 'content',
           content: {
@@ -374,6 +377,17 @@ export class ToolCallEmitter extends BaseEmitter {
     return null;
   }
 
+  private isTruncatedSessionDiffDisplay(resultDisplay: unknown): boolean {
+    if (!resultDisplay || typeof resultDisplay !== 'object') return false;
+
+    const obj = resultDisplay as Record<string, unknown>;
+    return (
+      obj['truncatedForSession'] === true &&
+      'fileName' in obj &&
+      'newContent' in obj
+    );
+  }
+
   /**
    * Transforms Part[] to ToolCallContent[].
    * Extracts text from functionResponse parts and text parts.

packages/web-shell/client/adapters/transcriptToMessages.test.ts

@@ -2328,6 +2328,12 @@ describe('transcriptBlocksToDaemonMessages', () => {
     const tool =
       messages[0].role === 'tool_group' ? messages[0].tools[0] : undefined;
     expect(tool?.rawOutput).toBeUndefined();
+    expect(tool?.content).toEqual([
+      {
+        type: 'content',
+        content: { type: 'text', text: 'rendered elsewhere' },
+      },
+    ]);
   });
 
   it('mergeToolCall updates fields from completion block', () => {
@@ -2582,7 +2588,7 @@ describe('transcriptBlocksToDaemonMessages', () => {
     expect(execTool?.subContent).toBe('Running...');
   });
 
-  it('does not pass content, locations, or preview to DaemonMessageToolCall', () => {
+  it('passes content but not locations or preview to DaemonMessageToolCall', () => {
     const messages = transcriptBlocksToDaemonMessages([
       toolBlock('t1', 'tc1', 'completed', 1, {
         toolName: 'Edit',
@@ -2603,7 +2609,14 @@ describe('transcriptBlocksToDaemonMessages', () => {
       messages[0].role === 'tool_group' ? messages[0].tools[0] : undefined;
     expect(tool).toBeDefined();
     expect(tool?.callId).toBe('tc1');
-    expect('content' in tool!).toBe(false);
+    expect(tool?.content).toEqual([
+      {
+        type: 'diff',
+        path: '/path/file.ts',
+        oldText: 'old',
+        newText: 'new',
+      },
+    ]);
     expect('locations' in tool!).toBe(false);
     expect('preview' in tool!).toBe(false);
   });

packages/web-shell/client/adapters/transcriptToMessages.ts

@@ -15,6 +15,7 @@ import type {
 import type {
   DaemonMessage,
   DaemonMessageToolCall,
+  DaemonMessageToolCallContent,
   DaemonMessageToolCallStatus,
   DaemonMessageToolKind,
   DaemonMessageTodoItem,
@@ -645,6 +646,7 @@ function daemonToolBlockToToolCall(
 ): DaemonMessageToolCall {
   const rawOutput = getToolRawOutput(block);
   const isBackgroundAgent = isBackgroundAgentBlock(block, rawOutput);
+  const content = normalizeToolContent(block.content);
   const statusMap: Record<string, DaemonMessageToolCallStatus> = {
     running: 'in_progress',
     pending: 'pending',
@@ -676,6 +678,7 @@ function daemonToolBlockToToolCall(
     parentToolCallId: block.parentToolCallId,
     startTime: block.createdAt,
     endTime: isComplete && !isBackgroundAgent ? block.updatedAt : undefined,
+    ...(content ? { content } : {}),
   };
 }
 
@@ -813,6 +816,59 @@ function getToolRawOutput(block: DaemonToolTranscriptBlock): unknown {
   };
 }
 
+function normalizeToolContent(
+  value: unknown,
+): DaemonMessageToolCallContent[] | undefined {
+  if (!Array.isArray(value)) return undefined;
+
+  const content = value.flatMap((entry): DaemonMessageToolCallContent[] => {
+    const item = getRecord(entry);
+    if (!item) return [];
+
+    const type = item['type'];
+    if (type === 'content') {
+      const body = getRecord(item['content']);
+      if (!body || typeof body['type'] !== 'string') return [];
+      return [
+        {
+          type: 'content',
+          content: { ...body, type: body['type'] },
+        },
+      ];
+    }
+
+    if (type === 'diff') {
+      const newText = item['newText'];
+      if (typeof newText !== 'string') return [];
+
+      const path = item['path'];
+      const oldText = item['oldText'];
+      return [
+        {
+          type: 'diff',
+          ...(typeof path === 'string' ? { path } : {}),
+          ...(typeof oldText === 'string' ? { oldText } : {}),
+          newText,
+        },
+      ];
+    }
+
+    if (type === 'terminal') {
+      const terminalId = item['terminalId'];
+      return [
+        {
+          type: 'terminal',
+          ...(typeof terminalId === 'string' ? { terminalId } : {}),
+        },
+      ];
+    }
+
+    return [];
+  });
+
+  return content.length > 0 ? content : undefined;
+}
+
 function isAskUserQuestionBlock(block: DaemonToolTranscriptBlock): boolean {
   if (!block.toolName) return false;
   const normalized = block.toolName.toLowerCase();

packages/web-shell/client/components/messages/ToolGroup.test.tsx

@@ -39,6 +39,15 @@ function makeShellTool(
   };
 }
 
+function makeEditTool(overrides: Partial<ACPToolCall>): ACPToolCall {
+  return {
+    callId: 'call-edit-1',
+    toolName: 'edit',
+    status: 'completed',
+    ...overrides,
+  };
+}
+
 function renderTool(tool: ACPToolCall): HTMLElement {
   const container = document.createElement('div');
   document.body.appendChild(container);
@@ -104,6 +113,14 @@ function click(el: Element): void {
   });
 }
 
+function expandTool(container: HTMLElement): void {
+  const chevron = [...container.querySelectorAll('span')].find(
+    (s) => s.textContent === '▸',
+  );
+  expect(chevron).toBeTruthy();
+  click(chevron!.parentElement!);
+}
+
 describe('shell tool output expand toggle', () => {
   it('shows short output in full without an expand button', () => {
     const container = renderShellTool('one\ntwo\nthree');
@@ -347,3 +364,104 @@ describe('auto-collapse on finish', () => {
     expect(container.textContent).toContain('▾');
   });
 });
+
+describe('edit raw diff rendering', () => {
+  it('ignores truncated session rawOutput diffs', () => {
+    const fullDiff = '--- a/file.ts\n+++ b/file.ts\n@@ -1 +1 @@\n-old\n+new';
+
+    const normal = renderTool(
+      makeEditTool({
+        rawOutput: {
+          fileDiff: fullDiff,
+        },
+      }),
+    );
+    expandTool(normal);
+    expect(normal.textContent).toContain('old');
+    expect(normal.textContent).toContain('new');
+
+    const truncated = renderTool(
+      makeEditTool({
+        rawOutput: {
+          fileName: '/test/file.ts',
+          newContent: 'preview only',
+          fileDiff: fullDiff,
+          truncatedForSession: true,
+        },
+      }),
+    );
+    expect(truncated.textContent).not.toContain('old');
+    expect(truncated.textContent).not.toContain('new');
+  });
+
+  it('shows preview and suppresses truncated rawOutput diffs', () => {
+    const fullDiff = '--- a/file.ts\n+++ b/file.ts\n@@ -1 +1 @@\n-old\n+new';
+    const preview =
+      'Full diff omitted from saved session history for /test/file.ts.';
+    const container = renderTool(
+      makeEditTool({
+        content: [
+          {
+            type: 'content',
+            content: { type: 'text', text: preview },
+          },
+        ],
+        rawOutput: {
+          fileName: '/test/file.ts',
+          newContent: 'preview only',
+          fileDiff: fullDiff,
+          truncatedForSession: true,
+        },
+      }),
+    );
+
+    expandTool(container);
+    expect(container.textContent).toContain(preview);
+    expect(container.textContent).not.toContain('old');
+    expect(container.textContent).not.toContain('new');
+  });
+
+  it('renders truncated session preview text when no diff is available', () => {
+    const preview =
+      'Full diff omitted from saved session history for /test/file.ts.';
+    const container = renderTool(
+      makeEditTool({
+        content: [
+          {
+            type: 'content',
+            content: { type: 'text', text: preview },
+          },
+        ],
+      }),
+    );
+
+    expandTool(container);
+    expect(container.textContent).toContain(preview);
+  });
+
+  it('expands write preview text when no diff is available', () => {
+    const preview =
+      'Full diff omitted from saved session history for /test/file.ts.';
+    const container = renderTool(
+      makeEditTool({
+        toolName: 'write',
+        content: [
+          {
+            type: 'content',
+            content: { type: 'text', text: preview },
+          },
+        ],
+      }),
+    );
+
+    expect(container.querySelector('pre')).toBeNull();
+
+    const writeLabel = Array.from(container.querySelectorAll('span')).find(
+      (el) => el.textContent === 'WriteFile',
+    );
+    expect(writeLabel).toBeDefined();
+    click(writeLabel!);
+
+    expect(container.querySelector('pre')?.textContent).toBe(preview);
+  });
+});