fix(desktop): show full tool error details (#625)

Surface expanded error output for tool cards whose previews previously returned before rendering the result body. Keep successful Bash/Read/Edit/Write outputs hidden as before while exposing error details with wrapping and copy support.

Tested: cd desktop && bun run test -- src/components/chat/chatBlocks.test.tsx
Tested: bun test src/server/__tests__/conversations.test.ts -t "should switch from bypass permissions back to default without restarting" --timeout=20000
Tested: bun run verify
Confidence: high
Scope-risk: narrow

desktop/src/components/chat/ToolCallBlock.tsx

@@ -131,57 +131,94 @@ function renderPreview(
   t?: (key: TranslationKey, params?: Record<string, string | number>) => string,
 ) {
   const filePath = typeof obj.file_path === 'string' ? obj.file_path : 'file'
+  const resultText = getVisibleResultText(toolName, result)
+  const resultOutput = result && resultText ? renderResultOutput(result, resultText, t) : null
 
   if (toolName === 'Edit' && typeof obj.old_string === 'string' && typeof obj.new_string === 'string') {
-    return <DiffViewer filePath={filePath} oldString={obj.old_string} newString={obj.new_string} />
+    return (
+      <>
+        <DiffViewer filePath={filePath} oldString={obj.old_string} newString={obj.new_string} />
+        {resultOutput}
+      </>
+    )
   }
 
   if (toolName === 'Write' && typeof obj.content === 'string') {
-    return <DiffViewer filePath={filePath} oldString="" newString={obj.content} />
+    return (
+      <>
+        <DiffViewer filePath={filePath} oldString="" newString={obj.content} />
+        {resultOutput}
+      </>
+    )
   }
 
   if (toolName === 'Bash' && typeof obj.command === 'string') {
     return (
-      <TerminalChrome title={typeof obj.description === 'string' ? obj.description : filePath}>
+      <>
-        <div className="px-3 py-2.5 font-[var(--font-mono)] text-[11px] leading-[1.3] text-[var(--color-terminal-fg)]">
+        <TerminalChrome title={typeof obj.description === 'string' ? obj.description : filePath}>
-          <span className="text-[var(--color-terminal-accent)]">$</span> {obj.command}
+          <div className="px-3 py-2.5 font-[var(--font-mono)] text-[11px] leading-[1.3] text-[var(--color-terminal-fg)]">
-        </div>
+            <span className="text-[var(--color-terminal-accent)]">$</span> {obj.command}
-      </TerminalChrome>
+          </div>
+        </TerminalChrome>
+        {resultOutput}
+      </>
     )
   }
 
   if (toolName === 'Read') {
-    return null
+    return resultOutput
   }
 
-  if (result) {
+  if (resultOutput) return resultOutput
-    const text = extractTextContent(result.content)
-    if (text) {
-      return (
-        <>
-          <InlineImageGallery text={text} />
-          <div className={`overflow-hidden rounded-lg border ${
-            result.isError
-              ? 'border-[var(--color-error)]/20 bg-[var(--color-error-container)]/60'
-              : 'border-[var(--color-border)] bg-[var(--color-surface)]'
-          }`}>
-            <div className="flex items-center justify-between border-b border-[var(--color-border)]/60 px-3 py-2 text-[10px] uppercase tracking-[0.18em] text-[var(--color-outline)]">
-              <span>{result.isError ? t?.('tool.errorOutput') ?? 'Error Output' : t?.('tool.toolOutput') ?? 'Tool Output'}</span>
-              <CopyButton
-                text={text}
-                className="rounded-md border border-[var(--color-border)] px-2 py-1 text-[10px] normal-case tracking-normal text-[var(--color-text-tertiary)] transition-colors hover:text-[var(--color-text-primary)]"
-              />
-            </div>
-            <CodeViewer code={text} language="plaintext" maxLines={18} />
-          </div>
-        </>
-      )
-    }
-  }
 
   return null
 }
 
+function getVisibleResultText(
+  toolName: string,
+  result?: { content: unknown; isError: boolean } | null,
+): string | null {
+  if (!result) return null
+  const text = extractTextContent(result.content)
+  if (!text) return null
+
+  if (result.isError) return text
+  if (toolName === 'Bash' || toolName === 'Read' || toolName === 'Edit' || toolName === 'Write') return null
+  return text
+}
+
+function renderResultOutput(
+  result: { content: unknown; isError: boolean },
+  text: string,
+  t?: (key: TranslationKey, params?: Record<string, string | number>) => string,
+) {
+  return (
+    <>
+      <InlineImageGallery text={text} />
+      <div className={`overflow-hidden rounded-lg border ${
+        result.isError
+          ? 'border-[var(--color-error)]/20 bg-[var(--color-error-container)]/60'
+          : 'border-[var(--color-border)] bg-[var(--color-surface)]'
+      }`}>
+        <div className="flex items-center justify-between border-b border-[var(--color-border)]/60 px-3 py-2 text-[10px] uppercase tracking-[0.18em] text-[var(--color-outline)]">
+          <span>{result.isError ? t?.('tool.errorOutput') ?? 'Error Output' : t?.('tool.toolOutput') ?? 'Tool Output'}</span>
+          <CopyButton
+            text={text}
+            className="rounded-md border border-[var(--color-border)] px-2 py-1 text-[10px] normal-case tracking-normal text-[var(--color-text-tertiary)] transition-colors hover:text-[var(--color-text-primary)]"
+          />
+        </div>
+        {result.isError ? (
+          <pre className="max-h-[420px] overflow-auto whitespace-pre-wrap break-words bg-[var(--color-code-bg)] px-3 py-2 font-[var(--font-mono)] text-[12px] leading-[1.45] text-[var(--color-error)]">
+            {text}
+          </pre>
+        ) : (
+          <CodeViewer code={text} language="plaintext" maxLines={18} />
+        )}
+      </div>
+    </>
+  )
+}
+
 function renderDetails(
   toolName: string,
   obj: Record<string, unknown>,

desktop/src/components/chat/chatBlocks.test.tsx

@@ -159,6 +159,84 @@ describe('chat blocks', () => {
     expect(container.textContent).toContain('fatal: unrecognized argument: --no-stat')
   })
 
+  it('shows full bash error output when the tool block is expanded', () => {
+    const lines = Array.from({ length: 8 }, (_, index) => `detail line ${index + 1}`)
+    const fullError = [
+      '<tool_use_error>InputValidationError: Bash failed due to the following issues: The required parameter `description` is missing.',
+      ...lines,
+      'final remediation hint: provide a concise command description.',
+    ].join('\n')
+    const { container } = render(
+      <ToolCallBlock
+        toolName="Bash"
+        input={{ command: 'bun run check:server' }}
+        result={{ content: fullError, isError: true }}
+      />,
+    )
+
+    expect(container.textContent).toContain('InputValidationError')
+    expect(container.textContent).not.toContain('final remediation hint')
+
+    fireEvent.click(screen.getByRole('button'))
+
+    expect(container.textContent).toContain('Error Output')
+    expect(container.textContent).toContain('detail line 8')
+    expect(container.textContent).toContain('final remediation hint')
+  })
+
+  it('shows read tool validation errors when the tool block is expanded', () => {
+    const fullError = [
+      '<tool_use_error>InputValidationError: Read failed due to the following issues:',
+      'The required parameter `file_path` is missing.',
+      'The provided limit must be greater than 0.',
+    ].join('\n')
+    const { container } = render(
+      <ToolCallBlock
+        toolName="Read"
+        input={{}}
+        result={{ content: fullError, isError: true }}
+      />,
+    )
+
+    expect(container.textContent).toContain('Read')
+    expect(container.textContent).not.toContain('file_path')
+
+    fireEvent.click(screen.getByRole('button'))
+
+    expect(container.textContent).toContain('Error Output')
+    expect(container.textContent).toContain('file_path')
+    expect(container.textContent).toContain('limit must be greater than 0')
+  })
+
+  it('keeps edit previews while showing edit tool error output when expanded', () => {
+    const { container } = render(
+      <ToolCallBlock
+        toolName="Edit"
+        input={{
+          file_path: '/tmp/example.ts',
+          old_string: 'const enabled = false',
+          new_string: 'const enabled = true',
+        }}
+        result={{
+          content: [
+            'InputValidationError: Edit failed due to the following issues:',
+            'The provided old_string was not found in the file.',
+          ].join('\n'),
+          isError: true,
+        }}
+      />,
+    )
+
+    expect(container.textContent).toContain('Edit')
+    expect(container.textContent).not.toContain('old_string was not found')
+
+    fireEvent.click(screen.getByRole('button'))
+
+    expect(container.textContent).toContain('example.ts')
+    expect(container.textContent).toContain('Error Output')
+    expect(container.textContent).toContain('old_string was not found')
+  })
+
   it('expands tool errors so full Computer Use gate messages are readable', () => {
     const { container } = render(
       <ToolCallBlock