Merge remote-tracking branch 'origin/master' into fix/web-sources-scroll

packages/client/ui-conversation/src/client/chat/AssistantMarkdown.tsx

@@ -4,9 +4,10 @@
 // view groups them into tool rows through its keyed toolview slot (figma
 // step-summary flow). Shared by finalized nodes and the streaming partial;
 // the turn-level loading dots live in the chat view's tail, not here.
-// Finalized turn-tail content (text) nodes append IconActions once streaming
-// ends (`time` is omitted for mid-turn narration); Think / tool-head-only
-// nodes stay chrome-free.
+// Finalized content (text) nodes append IconActions once streaming ends
+// (`time` is omitted for mid-turn narration); their branch action is enabled
+// only when the node is also the completed turn's transcript tail. Think /
+// tool-head-only nodes stay chrome-free.
 
 import { memo, useMemo } from 'react'
 import type { AssistantBlock } from '@deepseek-ai/dsh-client-runtime/client'
@@ -28,8 +29,10 @@ export interface AssistantMarkdownProps {
   time?: number | undefined
   /** Event sequence used as the fork boundary; omitted while streaming. */
   seq?: number | undefined
-  /** Fork the session through the turn containing this finalized message. */
+  /** Fork the session through this finalized message's completed turn when eligible. */
   onFork?: ((seq: number) => void) | undefined
+  /** The message is not the transcript tail of a completed turn. */
+  forkUnavailable?: boolean | undefined
   /** The owning view's locale seat, passed down as a plain prop. */
   t: ChatViewSlotProps['t']
 }
@@ -76,7 +79,7 @@ function ThinkRow({ text, running, t }: { text: string; running: boolean; t: Ass
 }
 
 export const AssistantMarkdown = memo(function AssistantMarkdown({
-  blocks, streaming, interrupted, time, seq, onFork, t,
+  blocks, streaming, interrupted, time, seq, onFork, forkUnavailable, t,
 }: AssistantMarkdownProps) {
   // Stable per locale revision (t identity changes on switch): a fresh object
   // per render would rebuild MarkdownText's component table every chunk.
@@ -120,6 +123,7 @@ export const AssistantMarkdown = memo(function AssistantMarkdown({
           time={time}
           clock="end"
           onBranch={onFork === undefined || seq === undefined ? undefined : () => { onFork(seq) }}
+          branchUnavailable={forkUnavailable}
           className={css.actions}
           t={t}
         />

packages/client/ui-conversation/src/client/chat/ChatView.tsx

@@ -30,7 +30,7 @@ import type {
 import type { SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
 import { IconChevronDownOutline14 } from '@deepseek-ai/dsh-client-ui-primitives'
 import type { ChatViewSlotProps } from '../contract/slots.ts'
-import { assistantActionsSeqs, deriveChatFlow, type ChatFlowItem } from './chat-flow.ts'
+import { assistantActionsSeqs, deriveChatFlow, messageBranchSeqs, type ChatFlowItem } from './chat-flow.ts'
 import { AssistantMarkdown } from './AssistantMarkdown.tsx'
 import { GenericCommandCard } from './GenericCommandCard.tsx'
 import { GenericToolCard } from './GenericToolCard.tsx'
@@ -236,6 +236,7 @@ export function ChatView({
   useSession, useSessions, useStore, renderSlot, sessionId, openFile, loadOlder, inspectCall, chatScroll, forkAt, t,
 }: ChatViewSlotProps) {
   const nodes = useSession(s => s.nodes)
+  const turnEnds = useSession(s => s.turnEnds)
   const inbox = useSession(s => s.queue)
   // Workspace root off the session list row: path summaries display relative to it.
   const cwd = useSessions(s => s.byId[sessionId]?.cwd)
@@ -257,6 +258,7 @@ export function ChatView({
   // Only the last content assistant of each turn owns IconActions; mid-turn
   // text (before tools) omits `time` so AssistantMarkdown stays chrome-free.
   const actionSeqs = useMemo(() => assistantActionsSeqs(nodes), [nodes])
+  const branchSeqs = useMemo(() => messageBranchSeqs(nodes, turnEnds), [nodes, turnEnds])
 
   const listRef = useRef<HTMLDivElement | null>(null)
   const atBottomRef = useRef(true)
@@ -413,6 +415,7 @@ export function ChatView({
           time={actionSeqs.has(node.seq) ? node.time : undefined}
           seq={node.seq}
           onFork={forkAt}
+          forkUnavailable={!branchSeqs.has(node.seq)}
           t={t}
         />
       )
@@ -428,6 +431,7 @@ export function ChatView({
         node={node}
         retryActive={node.kind === 'model-retry' && node.seq === activeRetry}
         onFork={forkAt}
+        forkUnavailable={!branchSeqs.has(node.seq)}
         t={t}
       />
     )

packages/client/ui-conversation/src/client/chat/MessageIconActions.module.css

@@ -43,3 +43,23 @@
   background: var(--dsw-alias-interactive-bg-hover);
   color: var(--dsw-alias-label-secondary);
 }
+
+/* Unavailable stays focusable and hoverable so Tooltip can explain why. */
+.action[data-unavailable] {
+  cursor: default;
+  opacity: 0.4;
+}
+
+.action[data-unavailable]:hover {
+  background: transparent;
+  color: var(--dsw-alias-label-tertiary);
+}
+
+.visuallyHidden {
+  position: absolute;
+  width: 1px;
+  height: 1px;
+  overflow: hidden;
+  clip: rect(0 0 0 0);
+  white-space: nowrap;
+}

packages/client/ui-conversation/src/client/chat/MessageIconActions.tsx

@@ -1,7 +1,7 @@
 // Shared IconActions chrome for user, steering, and assistant messages: copy
 // live, optional branch wiring, and an optional date-aware clock.
 
-import { useCallback } from 'react'
+import { useCallback, useId } from 'react'
 import {
   IconBranchOutline16, IconCopyOutline16, Tooltip,
 } from '@deepseek-ai/dsh-client-ui-primitives'
@@ -17,9 +17,11 @@ export interface MessageIconActionsProps {
   time?: number | undefined
   /** Clock before icons (user) or after (assistant). */
   clock: 'start' | 'end'
-  /** Fork the session at this message. */
+  /** Fork the session at this message; omission hides the branch action. */
   onBranch?: (() => void) | undefined
-  /** Whether to render the branch action; defaults to true. */
+  /** The message is not a completed transcript tail, so branch stays visible but unavailable. */
+  branchUnavailable?: boolean | undefined
+  /** Additional branch visibility gate for transient message chrome; defaults to true. */
   showBranch?: boolean | undefined
   /** Parent layout class composed onto the actions row. */
   className?: string | undefined
@@ -33,9 +35,10 @@ export interface MessageIconActionsProps {
  * @returns The actions row element.
  */
 export function MessageIconActions({
-  text, time, clock, onBranch, showBranch = true, className, t,
+  text, time, clock, onBranch, branchUnavailable = false, showBranch = true, className, t,
 }: MessageIconActionsProps) {
   const day = useCalendarDay()
+  const reasonId = useId()
   const onCopy = useCallback(() => {
     void writeClipboard(text)
   }, [text])
@@ -52,13 +55,25 @@ export function MessageIconActions({
           <IconCopyOutline16 />
         </button>
       </Tooltip>
-      {showBranch && (
-        <Tooltip label={t('message.branch')} side="bottom">
-          <button type="button" className={css.action} aria-label={t('message.branch')} onClick={onBranch}>
+      {showBranch && onBranch !== undefined && (
+        <Tooltip label={branchUnavailable ? t('message.branchUnavailable') : t('message.branch')} side="bottom">
+          {/* Native disabled buttons do not deliver the hover/focus events Tooltip needs. */}
+          <button
+            type="button"
+            className={css.action}
+            aria-label={t('message.branch')}
+            aria-disabled={branchUnavailable || undefined}
+            aria-describedby={branchUnavailable ? reasonId : undefined}
+            data-unavailable={branchUnavailable || undefined}
+            onClick={branchUnavailable ? undefined : onBranch}
+          >
             <IconBranchOutline16 />
           </button>
         </Tooltip>
       )}
+      {showBranch && onBranch !== undefined && branchUnavailable && (
+        <span id={reasonId} className={css.visuallyHidden}>{t('message.branchUnavailable')}</span>
+      )}
       {clock === 'end' ? clockEl : null}
     </div>
   )

packages/client/ui-conversation/src/client/chat/MessageItem.tsx

@@ -26,8 +26,10 @@ export interface MessageItemProps {
     | TurnErrorNode
     | UnknownSurfaceNode
   retryActive?: boolean
-  /** Fork the session through the turn containing this message (user-bubble branch action). */
+  /** Fork through this message's completed turn when eligible. */
   onFork?: (seq: number) => void
+  /** The message is not the transcript tail of a completed turn. */
+  forkUnavailable?: boolean
   /** The owning view's locale seat, passed down as a plain prop. */
   t: ChatViewSlotProps['t']
 }
@@ -220,7 +222,7 @@ export function PendingSteeringBubble({ content, t }: {
 }
 
 export const MessageItem = memo(function MessageItem({
-  node, retryActive = false, onFork, t,
+  node, retryActive = false, onFork, forkUnavailable = false, t,
 }: MessageItemProps) {
   const truncated = (total: number): string => t('json.truncated', { total })
   switch (node.kind) {
@@ -236,6 +238,7 @@ export const MessageItem = memo(function MessageItem({
               time={node.time}
               clock="start"
               onBranch={onFork === undefined ? undefined : () => { onFork(node.seq) }}
+              branchUnavailable={forkUnavailable}
               className={css.actions}
               t={t}
             />

packages/client/ui-conversation/src/client/chat/chat-flow.ts

@@ -5,8 +5,8 @@
  * reuse the first notice's row while projecting the latest retry turn.
  * Item identity keys are stable across snapshots so the list parent can
  * subscribe to keys only while rows subscribe to content. IconActions ownership
- * (last content assistant per turn) is derived here too so ChatView and the
- * flow share one gate.
+ * and completed-turn branch points are derived here too so ChatView and the
+ * flow share their gates.
  */
 import type {
   AssistantBlock, ConversationNode, ToolResultNode,
@@ -47,6 +47,39 @@ export function assistantActionsSeqs(nodes: readonly ConversationNode[]): Readon
   return new Set(lastByTurn.values())
 }
 
+/**
+ * Seq set of message rows that may fork: the last transcript node of a
+ * completed turn, when that node owns message chrome. A later tool, reasoning,
+ * error, or other transcript node leaves the earlier message's branch action
+ * unavailable because the Host would include the whole turn.
+ * @param nodes - snapshot nodes in event order.
+ * @param turnEnds - completed turn boundaries retained from the event window.
+ * @returns Message seq values whose visible position matches the fork boundary.
+ */
+export function messageBranchSeqs(
+  nodes: readonly ConversationNode[],
+  turnEnds: ReadonlyMap<number, number>,
+): ReadonlySet<number> {
+  const result = new Set<number>()
+  const boundaries = [...turnEnds].sort((a, b) => a[1] - b[1])
+  let nodeIndex = 0
+  for (const [turn, endSeq] of boundaries) {
+    let tail: ConversationNode | undefined
+    while (nodeIndex < nodes.length) {
+      const candidate = nodes[nodeIndex]
+      if (candidate === undefined || candidate.seq > endSeq) break
+      tail = candidate
+      nodeIndex++
+    }
+    if (tail?.kind === 'user'
+      || (tail?.kind === 'steering' && tail.turn === turn)
+      || (tail?.kind === 'assistant' && tail.turn === turn && hasContentText(tail.blocks))) {
+      result.add(tail.seq)
+    }
+  }
+  return result
+}
+
 /**
  * Group finalized nodes into the step-summary flow.
  * @param nodes - snapshot nodes in human-transcript and durable-notice order.

packages/client/ui-conversation/src/client/contract/slots.ts

@@ -461,7 +461,7 @@ export interface ChatViewInjected {
     /** Last recorded offset, or null when pinned or never recorded. */
     read: () => number | null
   }
-  /** Fork the session through the turn containing the message at `seq`, then open the child. */
+  /** Fork through the completed turn ending at the eligible message `seq`, then open the child. */
   forkAt: (seq: number) => void
 }
 

packages/client/ui-conversation/src/client/locales.ts

@@ -59,6 +59,7 @@ export const zh = {
   'message.unknownBlock': '未知内容块',
   'message.stopped': '已停止',
   'message.branch': '在新对话中分支',
+  'message.branchUnavailable': '仅可从已完成轮次的最后一条消息分支',
   'message.retry.active': '正在重试模型请求',
   'message.retry.cancelled': '模型请求重试已取消',
   'message.retry.started': '已重试模型请求',
@@ -166,6 +167,7 @@ export const en = {
   'message.unknownBlock': 'Unknown content block',
   'message.stopped': 'Stopped',
   'message.branch': 'Branch into a new conversation',
+  'message.branchUnavailable': 'Available only on the last message of a completed turn',
   'message.retry.active': 'Retrying model request',
   'message.retry.cancelled': 'Model request retry cancelled',
   'message.retry.started': 'Retried model request',