Merge branch 'master' into worktree/fix-multi-select-custom-answer

.agents/notes/implemented/bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.i18n.yaml

@@ -0,0 +1,6 @@
+# Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
+# side as of the last confirmed-consistent state. Both languages carry equal authority;
+# after editing either side, bring the other along and re-record with:
+#   pnpm run verify-translation-pairing --write .agents/notes/implemented/bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.md
+2026-08-02-message-fork-actions-require-completed-turn-tail.md: f2e7fd67b65a6ce4a86ba3f4405f78842be8f234
+2026-08-02-message-fork-actions-require-completed-turn-tail.zh.md: 2c3feeaa3ef01dbde67faa73257520918996f9c8

.agents/notes/implemented/bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.md

@@ -0,0 +1,29 @@
+# Agent Note: Message fork actions require a completed turn tail
+
+Status: implemented
+
+English | [中文](2026-08-02-message-fork-actions-require-completed-turn-tail.zh.md)
+
+## Problem
+
+The Web conversation attached branch to the last assistant node with nonempty text in each turn. A later tool result, interrupted reasoning node, or terminal error did not take ownership because those rows have no content-text IconActions. The branch icon could therefore appear beneath an assistant response while more rows from the same turn remained below it. The Host correctly expanded that message anchor through the containing `turn/end`, but the placement made the action look like a message-level cut and the child visibly inherited the same-turn suffix.
+
+## Decision
+
+`ConversationSnapshot.turnEnds` retains the completed turn boundaries present in the raw event window. The conversation view walks transcript nodes through each boundary and enables branch only when the boundary's last node is a user message, a durable steering message, or a content-bearing assistant message. Open turns have no eligible message, and a later tool result, reasoning-only interruption, turn error, or other transcript node leaves branch unavailable on earlier messages. The unavailable control stays visible, focusable, and hoverable; `aria-disabled`, a tooltip, and `aria-describedby` explain the completed-tail requirement without sending a Host request. Copy and clock remain available under their existing message chrome, and the Host's completed-turn fork semantics remain unchanged.
+
+This narrows the message eligibility established by the earlier [Web session fork action decision](../feature/2026-07-27-web-session-fork-actions.md). Session-row forking still selects the latest completed turn, and eligible message actions still pass their event seq through the shared client runtime operation.
+
+## Alternatives considered
+
+**Cut the event log at the clicked assistant message.** Rejected because an assistant message can sit inside an open step and can contain tool calls whose results occur later. A raw prefix at that seq is not a balanced turn and may not be a valid provider transcript.
+
+**Infer completion from `running` or the next user message.** Rejected because retry and steering turns need not align with the next visible user bubble, and a paged window may omit that later bubble. The durable `turn/end` event is the authoritative completion fact.
+
+**Hide branch from every interrupted turn.** Rejected because an aborted turn is durably closed and its final interrupted text can be the true transcript tail. Eligibility depends on the completed boundary and node order, not the outcome kind.
+
+**Hide ineligible message controls.** Rejected because a disappearing control does not explain the boundary requirement and shifts otherwise stable message chrome. A focusable unavailable control preserves the affordance while preventing the request.
+
+## Consequences
+
+An enabled branch icon denotes the same completed-turn boundary that the Host will copy. In the reported response → tool → interrupted Think shape, the response keeps copy, clock, and a disabled branch control that explains why it cannot act. This change deliberately does not provide same-turn transcript editing or a retry-before-turn operation; the Session-row action remains available when a reader wants to copy the latest completed turn in full. Runtime tests pin boundary projection and reference stability, while conversation tests cover assistant, user-only, and durable-steering tails plus unavailable controls caused by later tool and interrupted reasoning rows.

.agents/notes/implemented/bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.zh.md

@@ -0,0 +1,29 @@
+# Agent Note: 消息 fork 操作要求消息位于已完成轮次尾部
+
+Status: implemented
+
+[English](2026-08-02-message-fork-actions-require-completed-turn-tail.md) | 中文
+
+## 问题
+
+Web 会话把分支操作挂到每个轮次中最后一个文本非空的 assistant 节点上。如果后面还有工具结果、被中断的推理（reasoning）节点或终态错误，这些行也不会接管操作，因为它们没有内容文本 IconActions。因此，分支图标可能出现在 assistant 响应下方，而同一轮次的更多行仍位于其后。Host 会正确地把该消息锚点扩展到其所在的 `turn/end`，但图标位置使操作看起来像在消息级截断，子会话又会明显继承同轮次的后缀。
+
+## 决策
+
+`ConversationSnapshot.turnEnds` 保留原始事件窗口中的已完成轮次边界。会话视图按各边界遍历 transcript（文本记录）节点，仅当边界的最后一个节点是用户消息、持久 steering（中途引导）消息或含内容的 assistant 消息时才启用分支操作。开放轮次没有符合条件的消息；如果后面还有工具结果、只有推理内容的中断、轮次错误或其他 transcript 节点，较早消息上的分支操作会保持不可用。不可用的控件仍然可见、可聚焦、可悬停；`aria-disabled`、tooltip 与 `aria-describedby` 会说明已完成尾部这一要求，且不会发送 Host 请求。复制和时钟仍可在既有消息 chrome 下使用，Host 按已完成轮次 fork 的语义保持不变。
+
+本决策收紧了较早的 [Web 会话 fork 操作决策](../feature/2026-07-27-web-session-fork-actions.md)所定义的消息资格。Session 行 fork 仍选择最新的已完成轮次；符合条件的消息操作仍通过共享 client 运行时操作传递其事件 seq。
+
+## 考虑过的替代方案
+
+**在点击的 assistant 消息处截断事件日志。** 不予采纳：assistant 消息可能位于尚未结束的步骤内，也可能包含结果随后才出现的工具调用。以该 seq 截取的原始前缀并不是结构完整的轮次，也可能不是有效的提供方 transcript。
+
+**从 `running` 或下一条用户消息推断完成状态。** 不予采纳：重试轮次与 steering 轮次不一定和下一个可见用户气泡对齐，分页窗口也可能省略该气泡。持久 `turn/end` 事件才是权威的完成事实。
+
+**对每个被中断轮次隐藏分支。** 不予采纳：已中止的轮次会持久关闭，其最终的中断文本可能正是真正的 transcript 尾部。资格取决于已完成边界与节点顺序，而非结果类别。
+
+**隐藏不符合条件的消息控件。** 不予采纳：消失的控件无法说明边界要求，还会让本应稳定的消息 chrome 发生位移。保留可聚焦但不可用的控件，既能维持操作提示，也能阻止请求。
+
+## 后果
+
+启用的分支图标现在表示的已完成轮次边界与 Host 实际复制的边界一致。在所报告的「响应 → 工具 → 被中断的 Think」形态中，响应仍保留复制、时钟，以及一个说明无法操作原因的禁用分支控件。本变更刻意不提供同轮次 transcript 编辑，也不提供轮次前重试操作；当读者希望完整复制最新的已完成轮次时，仍可使用 Session 行操作。运行时测试固定边界投影和引用稳定性，会话测试则覆盖 assistant 尾部、纯用户消息尾部、持久 steering 尾部，以及后续工具行和被中断推理行导致的不可用控件。

.agents/notes/implemented/feature/2026-07-27-web-session-fork-actions.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-07-27-web-session-fork-actions.md
-2026-07-27-web-session-fork-actions.md: 58960169a2e499d953840e5769e7689b5cd48047
-2026-07-27-web-session-fork-actions.zh.md: ea2f9030f672f00fb91bce3546836689a7d41004
+2026-07-27-web-session-fork-actions.md: 578e59ec92e003fe5c8cdfe951a595f3a7371ecf
+2026-07-27-web-session-fork-actions.zh.md: d90124f6e6e164b0a1e0fce734f52976630cd848

.agents/notes/implemented/feature/2026-07-27-web-session-fork-actions.md

@@ -10,7 +10,9 @@ The Session store already provides a fork primitive that creates a child session
 
 ## Decision
 
-The Web Session-row menu and message IconActions share the client runtime's `sessions.fork` action. A Session row passes `{ sessionId, increaseTitle: true }`, so it forks at the source session's last completed turn; a user message or settled assistant content message passes `{ sessionId, atSeq: node.seq, increaseTitle: true }`, so it forks at the turn containing that event. Only the client consumes `increaseTitle`: after adding the child session to its local list, the client increments a trailing `(N)` or `（N）` in the source session's persisted title without changing bracket style, appends ` (1)` to an unnumbered title, and skips the rename when no persisted title exists; the Host fork request still contains only `sessionId` and the optional `atSeq`. The caller opens the child only after the rename succeeds; a fork or rename failure leaves the source session and current selection unchanged, while a child created before a rename failure remains in the list.
+The message-eligibility portion of this decision is narrowed by the [completed-turn-tail decision](../bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.md); the shared runtime action, injection ownership, title handling, and peer-list decisions remain current.
+
+The Web Session-row menu and message IconActions share the client runtime's `sessions.fork` action. A Session row passes `{ sessionId, increaseTitle: true }`, so it forks at the source session's last completed turn; an eligible completed-turn-tail message passes `{ sessionId, atSeq: node.seq, increaseTitle: true }`, so it forks at the turn ending at that message. Only the client consumes `increaseTitle`: after adding the child session to its local list, the client increments a trailing `(N)` or `（N）` in the source session's persisted title without changing bracket style, appends ` (1)` to an unnumbered title, and skips the rename when no persisted title exists; the Host fork request still contains only `sessionId` and the optional `atSeq`. The caller opens the child only after the rename succeeds; a fork or rename failure leaves the source session and current selection unchanged, while a child created before a rename failure remains in the list.
 
 `forkAt(seq)` touches the session service only in ui-conversation's apply injection layer; message components report only the event `seq`. Session rows likewise initiate the operation only through ui-workspace's injected callback. Neither presentation package owns session mutation state or duplicates the host's boundary evaluation.
 
@@ -28,6 +30,6 @@ Session lineage is not projected into a list hierarchy. WorkSpace mode displays
 
 ## Consequences
 
-Users can create forks from Session rows, user messages, or settled assistant content messages; all three entry points ultimately use the same runtime/host operation. Message entry points preserve the exact event boundary, while the list entry point preserves the “latest completed turn” shortcut. Successive fork titles increment through `(1)`, `(2)`, and so on instead of repeatedly appending `(1)`; titles with fullwidth parentheses retain that style. Every fork child immediately appears as an ordinary peer row, so the list no longer needs session expansion state, recursive nodes, or twist controls.
+Users can create forks from Session rows or eligible completed-turn-tail messages; both entry points ultimately use the same runtime/host operation. Message entry points preserve the exact event boundary, while the list entry point preserves the “latest completed turn” shortcut. Successive fork titles increment through `(1)`, `(2)`, and so on instead of repeatedly appending `(1)`; titles with fullwidth parentheses retain that style. Every fork child immediately appears as an ordinary peer row, so the list no longer needs session expansion state, recursive nodes, or twist controls.
 
-Fork and child-rename failures stay silent and preserve the source selection, preventing a derivation action from disrupting the current reading position; this tradeoff also means the UI does not yet expose a failure reason or retry entry point. Package tests separately pin the two message `seq` paths, title increments, and the peer-list derivation; `apps/web/tests/message-actions.e2e.ts` exercises assistant-message branching and Session-row menu branching through the assembled application.
+Fork and child-rename failures stay silent and preserve the source selection, preventing a derivation action from disrupting the current reading position; this tradeoff also means the UI does not yet expose a failure reason or retry entry point. Package tests pin eligible message `seq` forwarding, title increments, and the peer-list derivation; `apps/web/tests/message-actions.e2e.ts` exercises assistant-message branching and Session-row menu branching through the assembled application.

.agents/notes/implemented/feature/2026-07-27-web-session-fork-actions.zh.md

@@ -10,7 +10,9 @@ Session store 已提供按完成轮前缀创建子会话的 fork 原语，但 We
 
 ## Decision
 
-Web 的 session 行菜单与消息 IconActions 共用 client runtime 的 `sessions.fork` 操作。Session 行传 `{ sessionId, increaseTitle: true }`，因此在源会话最后一个已完成轮次处分支；用户消息与已定稿 assistant 内容消息传 `{ sessionId, atSeq: node.seq, increaseTitle: true }`，因此在包含该事件的轮次处分支。`increaseTitle` 只由 client 消费：子会话进入本地列表后，client 把源会话持久化标题尾部的 `(N)` 或 `（N）` 递增并保留括号样式，无编号时追加 ` (1)`，没有持久化标题时不改名；Host fork 请求仍只有 `sessionId` 与可选的 `atSeq`。改名成功后调用方才打开子会话；fork 或改名失败时保持源会话与当前选择不变，改名失败时已创建的子会话仍留在列表中。
+本决策中的消息资格部分由[已完成轮次尾部决策](../bug-fix/2026-08-02-message-fork-actions-require-completed-turn-tail.md)收紧；共享运行时操作、注入归属、标题处理和同级列表决策仍然有效。
+
+Web 的 session 行菜单与消息 IconActions 共用 client runtime 的 `sessions.fork` 操作。Session 行传 `{ sessionId, increaseTitle: true }`，因此在源会话最后一个已完成轮次处分支；符合条件且位于已完成轮次尾部的消息传 `{ sessionId, atSeq: node.seq, increaseTitle: true }`，因此在以该消息结束的轮次处分支。`increaseTitle` 只由 client 消费：子会话进入本地列表后，client 把源会话持久化标题尾部的 `(N)` 或 `（N）` 递增并保留括号样式，无编号时追加 ` (1)`，没有持久化标题时不改名；Host fork 请求仍只有 `sessionId` 与可选的 `atSeq`。改名成功后调用方才打开子会话；fork 或改名失败时保持源会话与当前选择不变，改名失败时已创建的子会话仍留在列表中。
 
 `forkAt(seq)` 只在 ui-conversation 的 apply 注入层接触 session 服务，消息组件只回传事件 `seq`。Session 行同理只通过 ui-workspace 的注入回调发起操作；两个呈现包都不持有 session mutation 状态，也不复制 host 的边界求值。
 
@@ -28,6 +30,6 @@ Session lineage 不投影成列表层级。WorkSpace 模式按 `WorkspaceView.se
 
 ## Consequences
 
-用户可从 session 行、用户消息或已定稿 assistant 内容消息创建分支，三处最终走同一个 runtime/host 操作；消息点位保留精确事件边界，列表点位保留「最新完成轮」快捷语义。连续 fork 的标题按 `(1)`、`(2)` 递增，而不是重复追加 `(1)`；全角括号标题保持全角样式。所有 fork 子会话立即作为普通同级行出现，列表不再需要 session 展开状态、递归节点或 twist 控件。
+用户可从 session 行或符合条件的已完成轮次尾部消息创建分支，两处最终走同一个 runtime/host 操作；消息点位保留精确事件边界，列表点位保留「最新完成轮」快捷语义。连续 fork 的标题按 `(1)`、`(2)` 递增，而不是重复追加 `(1)`；全角括号标题保持全角样式。所有 fork 子会话立即作为普通同级行出现，列表不再需要 session 展开状态、递归节点或 twist 控件。
 
-Fork 与子会话改名失败都保持静默并保留源选择，避免一个派生操作破坏当前阅读位置；该取舍也意味着 UI 暂不提供失败原因或重试入口。Package tests 分别钉住两种消息 `seq`、标题递增与同级列表派生，`apps/web/tests/message-actions.e2e.ts` 通过装配后的应用执行 assistant 消息分支与 session 行菜单分支。
+Fork 与子会话改名失败都保持静默并保留源选择，避免一个派生操作破坏当前阅读位置；该取舍也意味着 UI 暂不提供失败原因或重试入口。包级测试固定符合条件的消息 `seq` 转发、标题递增与同级列表派生，`apps/web/tests/message-actions.e2e.ts` 通过装配后的应用执行 assistant 消息分支与 session 行菜单分支。