Merge remote-tracking branch 'origin/master' into worktree/web-multimodal-image-input

# Conflicts:
#	packages/client/runtime/README.i18n.yaml
#	packages/client/ui-conversation/README.i18n.yaml
#	packages/client/ui-conversation/src/client/apply.ts
#	packages/client/ui-conversation/src/client/chat/AssistantMarkdown.tsx
#	packages/client/ui-conversation/src/client/chat/ChatView.tsx
#	packages/client/ui-conversation/src/client/chat/MessageItem.tsx
#	packages/client/ui-conversation/src/client/contract/slots.ts
#	packages/client/ui-conversation/tests/chat-view.spec.tsx
#	packages/host/apiproxy/README.i18n.yaml
#	packages/host/apiproxy/README.md
#	packages/host/apiproxy/README.zh.md
#	packages/host/apiproxy/src/api/sessions.ts

packages/client/connection/src/client/fixture.ts

@@ -1094,6 +1094,56 @@ export function createFixtureApi(options: FixtureOptions = {}): ApiProxy {
         const appended = logOf(sessionId).at(-1) as SessionEvent
         return ok(request, { title: normalized, seq: appended.seq })
       },
+      fork: (request) => {
+        const { sessionId, atSeq } = request.payload
+        const source = summaryOf(sessionId)
+        if (source === undefined) {
+          return err(request, {
+            code: 'session-not-found',
+            message: `no session ${sessionId}`,
+            details: { sessionId },
+          })
+        }
+        const log = logs.get(sessionId) ?? []
+        const lastSeq = log.at(-1)?.seq ?? -1
+        const anchoredBoundary = atSeq === undefined
+          ? undefined
+          : log.find(e => e.type === 'turn/end' && e.seq >= atSeq)
+        const boundary = anchoredBoundary
+          ?? (atSeq === undefined || atSeq > lastSeq
+            ? log.findLast(e => e.type === 'turn/end')
+            : undefined)
+        if (boundary === undefined) {
+          return err(request, {
+            code: 'fork-unavailable',
+            message: atSeq !== undefined && atSeq <= lastSeq
+              ? `session ${sessionId} has not completed the turn containing event ${String(atSeq)}`
+              : `session ${sessionId} has no completed turn`,
+            details: { sessionId },
+          })
+        }
+        let cut = boundary.seq + 1
+        while (cut < log.length && log[cut]?.type !== 'turn/start') cut++
+        const child: SessionSummary = {
+          sessionId: sid(`fx-${nextSession++}`), updatedAt: Date.now(), running: false, blank: false,
+          parentSessionId: sessionId,
+          ...source.cwd === undefined ? {} : { cwd: source.cwd },
+        }
+        logs.set(child.sessionId, log.slice(0, cut))
+        sessions.push(child)
+        emitHost({
+          type: 'host/session-added', sessionId: child.sessionId, blank: false,
+          parentSessionId: sessionId,
+          ...source.cwd === undefined ? {} : { cwd: source.cwd },
+        })
+        const workspace = workspaces.find(w => w.sessionIds.includes(sessionId))
+        if (workspace !== undefined) {
+          workspace.sessionIds = [child.sessionId, ...workspace.sessionIds]
+          workspace.updatedAt = new Date().toISOString()
+          emitHost({ type: 'host/workspace-changed', workspace: { ...workspace } })
+        }
+        return ok(request, { sessionId: child.sessionId })
+      },
       history: async (request) => {
         const log = logs.get(request.payload.sessionId) ?? []
         // Snapshot at request time, deliver after the transit delay (mirrors a real host under latency).
@@ -1690,6 +1740,7 @@ export class FixtureApiClient extends AbstractApiClient {
       case 'session.models': return this.api.sessions.models(request)
       case 'session.selectModel': return this.api.sessions.selectModel(request)
       case 'session.rename': return this.api.sessions.rename(request)
+      case 'session.fork': return this.api.sessions.fork(request)
       case 'session.prompt': return this.api.sessions.prompt(request)
       case 'session.attachment': return this.api.sessions.attachment(request)
       case 'session.updateQueue': return this.api.sessions.updateQueue(request)

packages/client/connection/tests/fake-api.ts

@@ -46,6 +46,7 @@ export class FakeApiClient implements IApiClient {
   onList: (payload: unknown) => Promise<RpcResponse<{ items: never[] }>> = () => Promise.resolve(ok({ items: [] }))
   onCreate: (payload: unknown) => Promise<RpcResponse<{ sessionId: SessionId }>> = () => Promise.resolve(ok({ sessionId: 'fk-new' as SessionId }))
   onRename: (payload: unknown) => Promise<RpcResponse<{ title: string; seq: number }>> = () => Promise.resolve(ok({ title: 'fk-renamed', seq: 0 }))
+  onFork: (payload: unknown) => Promise<RpcResponse<{ sessionId: SessionId }>> = () => Promise.resolve(ok({ sessionId: 'fk-fork' as SessionId }))
   onHistory: (payload: { sessionId: SessionId; beforeSeq?: number; maxMessages?: number })
   => Promise<RpcResponse<{ events: never[]; hasMore: boolean; modelTarget: ModelTarget }>> =
     () => Promise.resolve(ok({
@@ -101,6 +102,7 @@ export class FakeApiClient implements IApiClient {
     selectModel: (payload: ModelTarget & { sessionId: SessionId }) =>
       this.record('session.selectModel', payload, this.onSelectModel(payload)),
     rename: (payload: unknown) => this.record('session.rename', payload, this.onRename(payload)),
+    fork: (payload: unknown) => this.record('session.fork', payload, this.onFork(payload)),
     prompt: (payload: unknown) => this.record('session.prompt', payload, this.onPrompt(payload)),
     attachment: (payload: unknown) => this.record('session.attachment', payload, this.onAttachment(payload)),
     updateQueue: (payload: unknown) => this.record('session.updateQueue', payload, this.onUpdateQueue(payload)),