fix(acp): correct Claude refusal attribution

src/main/acp/runtime-events.test.ts

@@ -29,6 +29,37 @@ describe('ACP runtime event normalization', () => {
     })
   })
 
+  it('rewrites Claude Code policy attribution only for assistant messages', () => {
+    const text =
+      'API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy (https://www.anthropic.com/legal/aup). Try rephrasing the request in a new session or change your model.'
+    const notification: SessionNotification = {
+      sessionId: 'session-1',
+      update: {
+        sessionUpdate: 'agent_message_chunk',
+        content: { type: 'text', text }
+      }
+    }
+
+    expect(toAcpRuntimeEvent(notification, 'event-refusal', 1710000000000, true).text).toBe(
+      'The selected model declined to complete this response under its safety policy. Try rephrasing the request in a new session or change your model.'
+    )
+    expect(toAcpRuntimeEvent(notification, 'event-other-agent', 1710000000000).text).toBe(text)
+    expect(
+      toAcpRuntimeEvent(
+        {
+          sessionId: 'session-1',
+          update: {
+            sessionUpdate: 'user_message_chunk',
+            content: { type: 'text', text }
+          }
+        },
+        'event-user-refusal',
+        1710000000000,
+        true
+      ).text
+    ).toBe(text)
+  })
+
   it('preserves bounded assistant image chunks through the runtime fallback transport', () => {
     const notification: SessionNotification = {
       sessionId: 'session-1',

src/main/acp/runtime-events.ts

@@ -2,6 +2,7 @@ import type { ContentBlock, SessionNotification, ToolCallContent } from '@agentc
 
 import {
   ACP_MESSAGE_IMAGE_EVENT_TEXT,
+  normalizeClaudeCodeRefusalText,
   sanitizeAcpMessageImage,
   type AcpRuntimeEvent
 } from '../../shared/acp'
@@ -119,9 +120,15 @@ const contentToText = (content: ContentBlock): string => {
 // Image notifications can carry megabytes of base64. Keep only bounded display data on the event;
 // the internal text sentinel lets the existing runtime projection forward image-only messages.
 const normalizeMessageContent = (
-  content: ContentBlock
+  content: ContentBlock,
+  normalizeClaudeCodeRefusal = false
 ): Pick<AcpRuntimeEvent, 'text' | 'image'> => {
-  if (content.type !== 'image') return { text: contentToText(content) }
+  if (content.type !== 'image') {
+    const text = contentToText(content)
+    return {
+      text: normalizeClaudeCodeRefusal ? normalizeClaudeCodeRefusalText(text) : text
+    }
+  }
 
   const image = sanitizeAcpMessageImage(content)
 
@@ -230,7 +237,8 @@ const projectToolDetailPayload = (update: ToolCallUpdate): Partial<AcpRuntimeEve
 const toAcpRuntimeEvent = (
   notification: SessionNotification,
   id: string,
-  timestamp = Date.now()
+  timestamp = Date.now(),
+  normalizeClaudeCodeRefusal = false
 ): AcpRuntimeEvent => {
   const { sessionId, update } = notification
   const base = {
@@ -244,7 +252,7 @@ const toAcpRuntimeEvent = (
   // Group protocol update variants into the small set of event kinds the UI renders.
   switch (update.sessionUpdate) {
     case 'agent_message_chunk': {
-      const messageContent = normalizeMessageContent(update.content)
+      const messageContent = normalizeMessageContent(update.content, normalizeClaudeCodeRefusal)
 
       return {
         ...base,

src/main/acp/runtime.ts

@@ -2804,6 +2804,9 @@ class AcpRuntime {
     this.applySessionUpdateEffects(
       this.sessionUpdateProjector.project(notification, {
         kind: 'runtime',
+        framework:
+          this.sessionRegistry.lookup(sessionId)?.aggregate.snapshot().frameworkId ??
+          this.framework.id,
         appSessionId,
         eventId: this.nextEventId(),
         visible,

src/main/acp/session-update-projector.test.ts

@@ -75,6 +75,41 @@ describe('AcpSessionUpdateProjector', () => {
     expect(projector.project(notification, { ...routing, reconnectPending: true })).toEqual([])
   })
 
+  it('removes Claude Code policy attribution from visible refusal messages', () => {
+    const projector = new AcpSessionUpdateProjector()
+    const [context, refresh, visible] = projector.project(
+      {
+        sessionId: 'session-1',
+        update: {
+          sessionUpdate: 'agent_message_chunk',
+          content: {
+            type: 'text',
+            text: 'API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy (https://www.anthropic.com/legal/aup). Try rephrasing.'
+          }
+        }
+      },
+      {
+        kind: 'runtime',
+        framework: 'claude-code',
+        eventId: 'event-refusal',
+        visible: true,
+        reconnectPending: false,
+        mcpServerNames: []
+      }
+    )
+
+    expect([context.kind, refresh.kind, visible.kind]).toEqual([
+      'context-observation',
+      'context-refresh',
+      'visible-event'
+    ])
+    expect(visible).toMatchObject({
+      event: {
+        text: 'The selected model declined to complete this response under its safety policy. Try rephrasing.'
+      }
+    })
+  })
+
   it('projects hidden current-mode updates while a reconnect suppresses stale context effects', () => {
     const projector = new AcpSessionUpdateProjector()
     const notification: SessionNotification = {

src/main/acp/session-update-projector.ts

@@ -14,6 +14,7 @@ import {
 
 type RuntimeProjectionRouting = Readonly<{
   kind: 'runtime'
+  framework?: PermissionToolContext['framework']
   appSessionId?: string
   eventId: string
   timestamp?: number
@@ -138,7 +139,12 @@ class AcpSessionUpdateProjector {
     }
 
     const projection = this.codexSkillActivity.projectWithContext(
-      toAcpRuntimeEvent(routed, routing.eventId, routing.timestamp)
+      toAcpRuntimeEvent(
+        routed,
+        routing.eventId,
+        routing.timestamp,
+        routing.framework === 'claude-code'
+      )
     )
     const event = deepFreeze(projection.event)
     if (event.contextUsage && routing.reconnectPending) return Object.freeze([])

src/main/tasks/task-runner.ts

@@ -1,5 +1,9 @@
 import type { AcpRuntimeEvent } from '../../shared/acp'
-import { getAcpRuntimeEventImage, getAcpRuntimeEventText } from '../../shared/acp'
+import {
+  getAcpRuntimeEventImage,
+  getAcpRuntimeEventText,
+  normalizeClaudeCodeRefusalText
+} from '../../shared/acp'
 import type {
   ArtifactFile,
   FinalizeRunArtifactsRequest,
@@ -553,7 +557,13 @@ class TaskRunner {
       (event) => event.kind === 'message' && event.role === 'assistant'
     )
     const terminalStopEvent = [...events].reverse().find((event) => event.kind === 'stop')
-    const output = assistantEvents.map((event) => getAcpRuntimeEventText(event) ?? '').join('')
+    const streamedOutput = assistantEvents
+      .map((event) => getAcpRuntimeEventText(event) ?? '')
+      .join('')
+    const output =
+      session.agentFrameworkId === 'claude-code'
+        ? normalizeClaudeCodeRefusalText(streamedOutput)
+        : streamedOutput
     const images = assistantEvents
       .map((event) => {
         const image = getAcpRuntimeEventImage(event)

src/renderer/src/stores/session-store.test.ts

@@ -381,6 +381,35 @@ describe('session store', () => {
     expect(session.activeRun).toBeUndefined()
   })
 
+  it('normalizes a Claude refusal prefix after streamed chunks are merged', () => {
+    useSessionStore.getState().appendUserMessage({
+      sessionId: 'transport-session-1',
+      content: 'Search the web',
+      agentFrameworkId: 'claude-code'
+    })
+    useSessionStore.getState().appendAgentMessageChunk({
+      sessionId: 'transport-session-1',
+      streamId: 'assistant-message-1',
+      eventId: 'event-1',
+      content: 'API Error: Claude Code is unable to respond to this request, '
+    })
+    useSessionStore.getState().appendAgentMessageChunk({
+      sessionId: 'transport-session-1',
+      streamId: 'assistant-message-1',
+      eventId: 'event-2',
+      content:
+        'which appears to violate our Usage Policy (https://www.anthropic.com/legal/aup). Try rephrasing.'
+    })
+
+    const session = useSessionStore.getState().sessions[0]
+    expect(session.messages[1]?.content).toBe(
+      'The selected model declined to complete this response under its safety policy. Try rephrasing.'
+    )
+    expect(toPersistedSession(session).messages[1]?.content).toBe(
+      'The selected model declined to complete this response under its safety policy. Try rephrasing.'
+    )
+  })
+
   it('attaches whole-turn usage only to the final agent message for the active prompt', () => {
     useSessionStore.getState().appendUserMessage({
       sessionId: 'transport-session-1',

src/renderer/src/stores/session-store.ts

@@ -10,6 +10,7 @@ import type { ArtifactFile } from '../../../shared/artifacts'
 import { sanitizeActivityGroupTitle } from '../../../shared/activity-groups'
 import {
   MAX_ACP_SESSION_IMAGE_BYTES,
+  normalizeClaudeCodeRefusalText,
   sanitizeAcpMessageImage,
   type AcpContextUsage,
   type AcpMessageImage,
@@ -1471,6 +1472,12 @@ export const useSessionStore = create<SessionStore>((set, get) => ({
     const existingMessage = session.messages.find(
       (message) => message.role === 'agent' && message.streamId === streamId
     )
+    const mergedContent = (current = ''): string => {
+      const text = `${current}${content}`
+      return session.agentFrameworkId === 'claude-code'
+        ? normalizeClaudeCodeRefusalText(text)
+        : text
+    }
     const messageId = existingMessage?.id ?? createMessageId()
     const now = Date.now()
 
@@ -1493,7 +1500,7 @@ export const useSessionStore = create<SessionStore>((set, get) => ({
               message.id === existingMessage.id
                 ? {
                     ...message,
-                    content: `${message.content}${content}`,
+                    content: mergedContent(message.content),
                     images: sanitizedImage
                       ? sanitizeMessageImages([
                           ...(message.images ?? []),
@@ -1513,7 +1520,7 @@ export const useSessionStore = create<SessionStore>((set, get) => ({
         const agentMessage: ChatMessage = {
           id: messageId,
           role: 'agent',
-          content,
+          content: mergedContent(),
           status: 'streaming',
           streamId,
           responseToMessageId,

src/shared/acp.ts

@@ -382,6 +382,16 @@ export const getAcpRuntimeEventText = (event: AcpRuntimeEvent): string | undefin
     ? undefined
     : event.text
 
+const CLAUDE_CODE_USAGE_POLICY_REFUSAL_PREFIX =
+  'API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy (https://www.anthropic.com/legal/aup).'
+const PROVIDER_NEUTRAL_REFUSAL_PREFIX =
+  'The selected model declined to complete this response under its safety policy.'
+
+export const normalizeClaudeCodeRefusalText = (text: string): string =>
+  text.startsWith(CLAUDE_CODE_USAGE_POLICY_REFUSAL_PREFIX)
+    ? `${PROVIDER_NEUTRAL_REFUSAL_PREFIX}${text.slice(CLAUDE_CODE_USAGE_POLICY_REFUSAL_PREFIX.length)}`
+    : text
+
 export type AcpPermissionScope = 'once' | 'session' | 'project' | 'global'
 export type AcpPermissionGrantScope = Exclude<AcpPermissionScope, 'once'>