Merge remote-tracking branch 'origin/fix/human-transcript-projection' into fix/web-transcript-projection

# Conflicts:
#	packages/client/ui-conversation/README.i18n.yaml

.agents/notes/implemented/architecture/2026-07-25-web-client-session-scope-and-provide-channel.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/architecture/2026-07-25-web-client-session-scope-and-provide-channel.md
-2026-07-25-web-client-session-scope-and-provide-channel.md: 4496e3786ed4adb6e60dfd5cfad72e989657f649
-2026-07-25-web-client-session-scope-and-provide-channel.zh.md: 768dada95aacdb358115d496f45e7fc0eece0151
+2026-07-25-web-client-session-scope-and-provide-channel.md: d19b256b834110d3cbb540cc0e039e61c693e98c
+2026-07-25-web-client-session-scope-and-provide-channel.zh.md: 1f88dd2065eaba7282ae3ed9e82d6872fdfb8497

.agents/notes/implemented/architecture/2026-07-25-web-client-session-scope-and-provide-channel.md

@@ -90,10 +90,10 @@ The sole provisioning path by which session slot components fetch their own sess
 Slot scope is the closed set `root | session-maybe | session`:
 
 - `root` receives only the global standard kit, with no session identity or provisioning.
-- `session-maybe` follows the current session, but the component instance does not change key when the id appears, disappears, or changes; with no session, `sessionId`, the results of `useSession`/`useInput`, and `inputActions` may all be absent. The unkeyed root `SessionMaybeProvider` drives these updates by subscribing to the runtime's atomic `currentProvide` projection — selection moves and provider-roster changes publish through the same source, so a roster change under a stable current id republishes the mounted bundle instead of stranding entries on an obsolete hook/prop schema — while `SessionMaybeProvideInfo` uses the static key map to retain the complete hook/prop shape even with no session.
+- `session-maybe` follows the current session with ADOPTION identity (the only behavior — there is no hold-identity-forever mode): an incarnation born session-less keeps its React instance across the arrival of the FIRST session (the blank shell adopts it — no remount, the DOM survives), and from then on behaves exactly like a strict session entry — switching to a different session remounts, and dropping back to no-session remounts into a fresh blank incarnation that will adopt again. Component-local per-session state therefore clears by construction; state that must survive a switch belongs in session-bound sources (machine, store, hooks). With no session, `sessionId`, the results of `useSession`/`useInput`, and `inputActions` may all be absent. The unkeyed root `SessionMaybeProvider` drives these updates by subscribing to the runtime's atomic `currentProvide` projection — selection moves and provider-roster changes publish through the same source, so a roster change under a stable current id republishes the mounted bundle instead of stranding entries on an obsolete hook/prop schema — while `SessionMaybeProvideInfo` uses the static key map to retain the complete hook/prop shape even with no session; the per-entry adoption bookkeeping (incarnation-counter key) lives in the renderer's `SessionMaybeEntry`.
 - `session` guarantees that `sessionId`, every hook source, and every prop exist; each strict entry's error boundary is keyed by `sessionId`, so switching sessions recreates that entry and its session store.
 
-`conversation` is the resident `session-maybe` shell: `ConversationRoot`, HeroShell, the Workspace picker, the composer stack, and the overlay chain's fallback frame retain their React instances across the no-session → blank-session switch; `conversation.session` carries only the strict-session header/view, while the composer and every input slot also stay strict `session`. With no session, the composer stack places the presentation-only `DisabledInputBar` directly; once a session appears, the input body is swapped for the strictly bound InputBar; the textarea may be rebuilt, while the Hero and the layout skeleton are not. The blank → engaging/active transition stays inside the same strict-session subtree, and the InputBar is never rebuilt on a phase flip.
+`conversation` is the resident `session-maybe` shell: `ConversationRoot`, HeroShell, the Workspace picker, the composer stack, and the overlay chain's fallback frame retain their React instances across the no-session → blank-session switch; `conversation.session` carries only the strict-session header/view. The composer bar (`conversation.composer.bar`) is itself `session-maybe`: with no session it renders inert (machine faces absent, `disabled` owner prop), and the same instance — textarea included — goes live when a session appears; the remaining input slots stay strict `session` and dispatch nothing until then. The blank → engaging/active transition never rebuilds the InputBar on a phase flip.
 
 - The runtime's first built-in entry: the `'session'` hook — `useSession` itself rides the same mechanism, no special-casing.
 - Concurrent discipline: the render plane reads only from the hooks compartment (uSES consistency guarantee); props-compartment callbacks are used only in event-handler space; descriptor resolution is render-safe (idempotent caching, with prune reaping residue from abandoned renders).

.agents/notes/implemented/architecture/2026-07-25-web-client-session-scope-and-provide-channel.zh.md

@@ -90,10 +90,10 @@ session slot 组件「自己拿 session 数据」的唯一供数路径。插件
 slot scope 是闭集 `root | session-maybe | session`：
 
 - `root` 只拿全局标准件，不接收 session 身份或供数。
-- `session-maybe` 跟随 current session，但组件实例不因 id 有无或切换而换 key；无 session 时 `sessionId`、`useSession`/`useInput` 的选择结果及 `inputActions` 均可缺省。根部无 key 的 `SessionMaybeProvider` 通过订阅 runtime 的原子 `currentProvide` 投影驱动这条更新——选择移动与 provider 名册变化经同一 source 发布，current id 不变时的名册变化也会重发已挂载 bundle，而不是把 entry 困在过期的 hook/prop 形状上——`SessionMaybeProvideInfo` 靠静态键表在无 session 时仍保留完整 hook/prop 形状。
+- `session-maybe` 以**收养（adoption）身份语义**跟随 current session（唯一行为——不存在「永久保持实例」模式）：空态出生的化身在**第一个** session 到来时保持 React 实例（空壳收养它——不重挂，DOM 存活）；此后行为与严格 session entry 完全一致——切到不同 session 重挂，跌回无 session 也重挂为崭新的空态化身（之后再次收养）。因此组件本地的 per-session 状态**由构造保证**随切换清零；需要活过切换的状态必须住 session 绑定的源（machine、store、hooks）。无 session 时 `sessionId`、`useSession`/`useInput` 的选择结果及 `inputActions` 均可缺省。根部无 key 的 `SessionMaybeProvider` 通过订阅 runtime 的原子 `currentProvide` 投影驱动这条更新——选择移动与 provider 名册变化经同一 source 发布，current id 不变时的名册变化也会重发已挂载 bundle，而不是把 entry 困在过期的 hook/prop 形状上——`SessionMaybeProvideInfo` 靠静态键表在无 session 时仍保留完整 hook/prop 形状；逐 entry 的收养记账（化身计数 key）住在 renderer 的 `SessionMaybeEntry`。
 - `session` 保证 `sessionId`、所有 hook source 与 props 均存在；每个严格 entry 的错误边界以 `sessionId` 为 key，切换 session 会重建该 entry 及其 session store。
 
-`conversation` 是 `session-maybe` 的常驻外壳：`ConversationRoot`、HeroShell、Workspace picker、composer stack 与 overlay chain 的 fallback 外框在无 session → blank session 的切换中保持 React 实例；`conversation.session` 只承载严格 session 的 header/view，composer 与各输入 slot 也保持严格 `session`。无 session 时 composer stack 直接放纯展示的 `DisabledInputBar`，session 出现后把输入体换成严格绑定的 InputBar；textarea 允许重建，Hero 与布局骨架不重建。blank → engaging/active 仍在同一严格 session subtree 内，InputBar 不因 phase 翻转而重建。
+`conversation` 是 `session-maybe` 的常驻外壳：`ConversationRoot`、HeroShell、Workspace picker、composer stack 与 overlay chain 的 fallback 外框在无 session → blank session 的切换中保持 React 实例；`conversation.session` 只承载严格 session 的 header/view。composer bar（`conversation.composer.bar`）本身即为 `session-maybe`：无 session 时以惰性态渲染（machine face 缺席、`disabled` owner prop），session 出现后同一实例（含 textarea）转为 live；其余输入 slot 保持严格 `session`，在此之前不分发任何条目。blank → engaging/active 的 InputBar 不因 phase 翻转而重建。
 
 - runtime 内建第一条：`'session'` hook——`useSession` 本身走同一机制，无特判。
 - Concurrent 纪律：渲染平面只从 hooks 格读（uSES 一致性保证）；props 格回调只在事件 handler 空间用；描述符解析 render-safe（幂等缓存、废弃渲染残留由 prune 收尸）。

.agents/notes/implemented/architecture/2026-07-25-web-input-machine-and-slash-pipeline.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/architecture/2026-07-25-web-input-machine-and-slash-pipeline.md
-2026-07-25-web-input-machine-and-slash-pipeline.md: f446f42c9e202afcb404c7a551a4f715228bb8e5
-2026-07-25-web-input-machine-and-slash-pipeline.zh.md: 8f5e449bb878811b70bc5bc29e4a09bbc1a33bfa
+2026-07-25-web-input-machine-and-slash-pipeline.md: 92bb91c3e892d928cedf18ec57c725a116b6ffc8
+2026-07-25-web-input-machine-and-slash-pipeline.zh.md: 5bee6df52f16d935aa4f4ccff8627a2d43d44c8c

.agents/notes/implemented/architecture/2026-07-25-web-input-machine-and-slash-pipeline.md

@@ -70,7 +70,7 @@ A trigger/menu/pick pipeline with zero knowledge of "commands":
 
 - The hub (trigger/decoration registries + send orchestration) takes the slash/command services as optional `ctx.get()` dependencies: without ui-slash or the command surfaces, input still sends and receives normally — graceful degradation.
 - Each materialized Session has exactly one `SessionInputShell` (the facade), created and torn down with the session scope; with no session, no input machine is built. `ConversationRoot` is itself the `session-maybe` resident shell, holding HeroShell, the Workspace picker, the composer stack, and the chain-fallback frame.
-- With no session the shell renders the presentation-only `DisabledInputBar`; once `connectWorkspace` returns a blank session, only the input body is swapped for the strict-session InputBar. The textarea may be rebuilt here, while `ConversationRoot`, the Hero, and the layout skeleton hold; blank → engaging/active stays the same session-bound InputBar, with the textarea never rebuilt on a phase flip.
+- The composer bar is one `session-maybe` slot entry rendered unconditionally: with no session the same InputBar renders inert (machine faces absent, `disabled` owner prop), and once `connectWorkspace` returns a blank session the same instance goes live — the textarea DOM survives the no-session → blank transition and every later phase flip; `ConversationRoot`, the Hero, and the layout skeleton hold throughout.
 - ConversationRoot's Hero criterion is `sessionId === undefined || (composerPhase === 'blank' && (openState === 'open' || openState === 'loading'))`. The first submit enters engaging synchronously, and a failure keeps the composer and the error context rather than falling back to the blank Hero; the sidebar's blank bit flips false only after a prompt is successfully accepted.
 - Sending unifies in the hub defaultSink: after an optimistic draft clear it goes only through `session.prompt {mode:'queue'|'steer'}`; backfill happens only when it fails and the live draft is still empty — a user who has kept typing is never overwritten. No Draft materialize or attach transaction exists.
 - When the blank Hero re-picks the Workspace, the shell calls `connectWorkspace`; if the target session differs, the non-empty draft moves from the current shell to the target shell before the new id is opened, and the old blank session survives but is no longer current.

.agents/notes/implemented/architecture/2026-07-25-web-input-machine-and-slash-pipeline.zh.md

@@ -70,7 +70,7 @@ occurrence 表与 chip 三投影：
 
 - hub（trigger/decoration 注册表 + 发送编排）对 slash/command 服务是可选 `ctx.get()` 依赖：无 ui-slash/命令面时输入正常收发，优雅降级。
 - 每个实体 Session 只有一个 `SessionInputShell`（facade），随 session scope 创建和拆除；无 session 时不造 input machine。`ConversationRoot` 自身是 `session-maybe` 常驻外壳，持有 HeroShell、Workspace picker、composer stack 与 chain fallback 外框。
-- 无 session 时外壳渲染纯展示的 `DisabledInputBar`；`connectWorkspace` 返回 blank session 后，仅输入体换成严格 session 的 InputBar。这里允许 textarea 重建，`ConversationRoot`、Hero 与布局骨架保持；blank → engaging/active 仍是同一 session-bound InputBar，textarea 不因 phase 翻转而重建。
+- composer bar 是一个无条件渲染的 `session-maybe` slot entry：无 session 时同一个 InputBar 以惰性态渲染（machine face 缺席、`disabled` owner prop），`connectWorkspace` 返回 blank session 后同一实例转为 live——textarea DOM 在无 session → blank 切换及其后每次 phase 翻转中都不重建；`ConversationRoot`、Hero 与布局骨架全程保持。
 - ConversationRoot 的 Hero 判据是 `sessionId === undefined || (composerPhase === 'blank' && (openState === 'open' || openState === 'loading'))`。首次 submit 同步进入 engaging，失败也保留 composer 与错误上下文，不退回 blank Hero；sidebar 的 blank 位只在 prompt 成功受理后翻 false。
 - 发送统一在 hub defaultSink：乐观清稿后只走 `session.prompt {mode:'queue'|'steer'}`；失败且 live draft 仍为空才回填，用户已经继续输入则不覆盖。不存在 Draft materialize 或 attach 事务。
 - blank Hero 改选 Workspace 时，外壳调用 `connectWorkspace`；目标 session 不同时把非空 draft 从当前 shell 搬到目标 shell，再 open 新 id，旧 blank session 留存但不再 current。

.agents/notes/implemented/architecture/2026-07-30-session-end-seed-log-boundary.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/architecture/2026-07-30-session-end-seed-log-boundary.md
+2026-07-30-session-end-seed-log-boundary.md: 837531ba0bd3ecf404eb47ee933438546c682a54
+2026-07-30-session-end-seed-log-boundary.zh.md: 33680c1845364de62e5b53ead13de418a389f908

.agents/notes/implemented/architecture/2026-07-30-session-end-seed-log-boundary.md

@@ -0,0 +1,55 @@
+# Agent Note: the end-seed log boundary
+
+Status: implemented
+
+English | [中文](2026-07-30-session-end-seed-log-boundary.zh.md)
+
+## Problem
+
+A plugin that owns a standalone open/close bracket in the session log cannot tell a dead marker from a live one. `compact/start` … `compact/end` is the shipped case: on picking up a log whose last compaction event is an unmatched `compact/start`, "the previous writer died mid-compaction" and "a compaction is running right now" are byte-identical stored history. The owner must either refuse to compact a log that is actually free (wedging the session) or proceed over one that is genuinely busy.
+
+Nothing in the log marked where inherited history ended. `session/created`, `session/disposed`, and `session/flush` are cordis runtime signals, not log events; `agent/session-start` is emit-only. `Session.firstLiveSeq` already held the answer exactly — the seq of this lifecycle's first own write — but only in memory, so a consumer reading stored bytes could not see it.
+
+Crash repair does not close the gap and must not: `interruptedTurnClosers` synthesizes turn, step, and tool boundaries because core owns that vocabulary, and `compact/*` belongs to the compaction seam. A core repair pass that closed plugin brackets would put every plugin's bracket semantics in core.
+
+## Decision
+
+`Session`'s constructor appends the log-only `session/end-seed` event immediately after a non-empty constructor seed, as the seeded session's first live write at the seq `firstLiveSeq` names. The event is the durable projection of that field: `firstLiveSeq` answers where this lifecycle's writes start for a consumer holding the object, while `session/end-seed` answers the same question for one holding only stored bytes. Its payload is empty — position and `time` carry the whole meaning — and it is not a `SurfaceEventType`, so it produces no message and cannot perturb derived history.
+
+A bracket owner reads it positionally: an unmatched opening marker before `session/end-seed` has a smaller seq, came from the constructor seed, and belongs to a lifecycle that has ended. Core writes the boundary and reads nothing from it; each bracket's vocabulary stays with its owning plugin, so no core predicate helper ships without a consumer to shape it.
+
+The constructor is the placement because it is the single waist every seeded session passes through. All six entry points reach it: `agents.resume()`, config-driven startup on a persisted id (`restoreOrCreateConfigured`), `sessions.fork()`, a subagent fork child, `coordinator.adopt()`'s live-prefix path, and a bare `sessions.create(id, {seed})`. A boundary written at persistence load would miss both fork paths — and a forked child inheriting a still-running parent's open `compact/start` is precisely the case that must be classifiable. A boundary written at loop start would miss `fork()` and `adopt()`, and would have to fire on `SessionStartSource: 'startup'`, which is what a fork child publishes, so that field would stop discriminating.
+
+Two guards keep the marker from becoming noise. An empty seed writes nothing because there is no seed to end. A seed already ending in one is not re-marked, which makes the write idempotent. Idempotence is load-bearing rather than tidiness — `agentFor()` resumes a cold session on first touch, so merely opening one in a client is a pickup, and without the guard browsing would grow a log by one event per visit.
+
+## Persistence needs no changes
+
+The constructor append happens before `enter()`, so the session has no store attachment: the marker never publishes on `session/event`, exactly like the seed events before it. It is instead part of the log `initFor` captures as the creation seed, and persists through the ordinary seed path — `onCreated`'s `createCore` + `appendCore`, or the ownerless-claim suffix write. A consumer that watches the firehose therefore never sees the boundary and must read it from the log.
+
+Consequences for the seam: `load()` stays a pure read, with no revision bump, no `commitRepair` on a balanced log, and no durable mark left by a rejected `append`. **Attaching is not a pure read**, though — a pickup now writes where nothing was written before, so a read-only or full disk fails at `session/created` rather than at the first real turn. That is the one cost this placement adds, and it is narrower than the load-path version's (which failed the load itself).
+
+A crash before the seed write reaches disk loses the boundary, and that costs nothing: the pending batch is written in order, so a lost boundary means every event after it is lost too. The next pickup reads the same bytes the previous one did, appends its own boundary, and classifies the bracket identically. In-process consumers should prefer `firstLiveSeq`, which is exact before any write.
+
+## Scope of the guarantee
+
+The predicate holds for a bracket *this* session inherited, not as a liveness signal about other writers. A concurrently live session may hold an open bracket over the same stored history while its own boundary sits elsewhere. A consumer that must tolerate concurrent writers needs a liveness signal beyond the log and cannot omit it on the strength of this event.
+
+## Alternatives considered
+
+**A boundary written by the persistence coordinator's cold-load path.** Built first, as the [`session/resumed` boundary](../../rejected/architecture/2026-07-29-session-resumed-log-boundary.md), and abandoned before merge. It covers no fork, which is the one case where the inherited bracket's owner may still be running. Because the marker was minted at load it also had to be a durable write on a read path, which spread cost across the seam: a revision bump on every cold load, a `commitRepair` batch on a balanced log with nothing to repair, a stored-time floor to keep the clamp monotonic, and a load that failed against a read-only store.
+
+**A boundary appended at loop start.** The loop calls `resumeWith`, so it covers the resume paths, but it misses `fork()` and `adopt()` entirely, and the event would have to fire on `'startup'` — the source a fork child publishes — so `SessionStartSource` would stop discriminating. It also publishes the session before the marker is appended, so a `session/created` listener could observe a seeded log with no boundary.
+
+**Reusing `header.seedLength`.** It is the durable *fork-lineage* boundary and deliberately keeps the original fork value across a resume, where the constructor seed is the whole stored log. The two facts differ and conflating them would lose both.
+
+**Crash repair closing `compact/*` alongside turn boundaries.** Rejected: it moves every plugin's bracket semantics into core's repair pass, and core cannot know what closing another package's bracket should record.
+
+## Consequences
+
+Bought: one boundary, written in one place, correct for all six seeded-start paths — including the fork gap the persistence-layer version could not reach. The persistence packages keep a pure read path. `firstLiveSeq` gains a durable twin rather than a second, competing notion of the same boundary.
+
+Cost: a seeded session's log is one event longer, which moved seq expectations in tests across nine packages (session, agent-loop, persistence contract, jsonl, session-query, session-title, subagent-inprocess, telemetry, token-meter). Two of those updates are load-bearing rather than mechanical: telemetry's adoption tests now assert the boundary IS exported, because it is this lifecycle's own write, and the property suite's replay invariant is restated as "seed reproduced verbatim, plus one log-only boundary" with idempotence added as its own property.
+
+`session/end-seed` joins the on-disk vocabulary. Under the pre-release stance (`SESSION_FORMAT_VERSION` pinned at `0`, no compatibility promise) older logs simply lack it, and a log without a boundary correctly classifies nothing as constructor-seed history.
+
+Not built here: no plugin reads the boundary yet. Wiring the compaction seam's staleness check to it is the follow-up that motivated this boundary; the predicate helper belongs with that seam, where a real consumer decides its shape, rather than shipping into core untested against one.

.agents/notes/implemented/architecture/2026-07-30-session-end-seed-log-boundary.zh.md

@@ -0,0 +1,55 @@
+# Agent Note: 种子结束日志边界
+
+Status: implemented
+
+[English](2026-07-30-session-end-seed-log-boundary.md) | 中文
+
+## Problem
+
+拥有独立开／闭括号的插件无法区分一个已死的标记和一个存活的标记。`compact/start` … `compact/end` 就是已发布的实例：当接手一份日志、而它最后的压缩事件是一个未配对的 `compact/start` 时，"上一个写入方在压缩中途死掉了"与"此刻正有一次压缩在运行"在存储历史中是逐字节相同的。所有方只能二选一：拒绝压缩一份其实空闲的日志（把会话卡死），或者在一份确实繁忙的日志上继续压缩。
+
+日志中没有任何东西标出继承历史在哪里结束。`session/created`、`session/disposed` 与 `session/flush` 是 cordis 运行时信号，不是日志事件；`agent/session-start` 只发射不落盘。`Session.firstLiveSeq` 本来就精确地持有这个答案——本生命周期第一次自有写入的 seq——但只存在于内存中，因此读取存储字节的消费方看不到它。
+
+崩溃修复既没有填上这个缺口，也不应该去填：`interruptedTurnClosers` 合成轮次、步骤与工具边界，是因为核心拥有那套词汇表，而 `compact/*` 属于压缩 seam。一个会关闭插件括号的核心修复流程，等于把每个插件的括号语义都搬进核心。
+
+## Decision
+
+`Session` 的构造函数紧接非空构造种子之后追加仅日志事件 `session/end-seed`，作为带种子会话的第一次实时写入，位置正是 `firstLiveSeq` 指出的 seq。该事件是那个字段的持久投影：`firstLiveSeq` 为持有对象的消费方回答本生命周期的写入从哪里开始，`session/end-seed` 则为只持有存储字节的消费方回答同一问题。它的 payload 为空——位置与 `time` 承载全部含义——并且不是 `SurfaceEventType`，因此不产生消息，也无法扰动派生历史。
+
+括号所有方按位置读取它：在 `session/end-seed` 之前的未配对开启标记具有更小的 seq，来自构造种子，并且属于一个已结束的生命周期。核心写入该边界但不从中读取任何内容；每个括号的词汇表仍归其所属插件，因此在没有消费方来塑形之前，核心不会先发布谓词辅助函数。
+
+选择构造函数，是因为它是每一个带种子会话都必经的唯一收窄处。全部六个入口都会到达它：`agents.resume()`、在已持久化 id 上的配置驱动启动（`restoreOrCreateConfigured`）、`sessions.fork()`、子代理 fork 子会话、`coordinator.adopt()` 的实时前缀路径，以及裸的 `sessions.create(id, {seed})`。在持久化加载时写入的边界会漏掉两条 fork 路径——而一个继承了仍在运行的父会话开放 `compact/start` 的 fork 子会话，恰恰是必须可判定的场景。在 loop 启动时写入的边界会漏掉 `fork()` 与 `adopt()`，并且不得不在 `SessionStartSource: 'startup'` 上触发——那正是 fork 子会话发布的取值，于是该字段将不再具有区分力。
+
+两条守卫让这个标记不至于变成噪声。空种子不写入任何内容，因为没有种子需要结束。种子本身已以该事件结尾时不会重复标记，这让写入具备幂等性。幂等性是承重的，而不是为了整洁——`agentFor()` 会在首次触碰时恢复一个冷会话，因此在客户端里仅仅打开一个会话就是一次接手；没有这条守卫，浏览会让日志每访问一次就增长一个事件。
+
+## 持久化无需任何改动
+
+构造函数中的 append 发生在 `enter()` 之前，因此会话尚无 store attachment：该标记不会在 `session/event` 上发布，与它之前的种子事件完全一样。它属于 `initFor` 捕获的那份创建种子，并通过普通的种子路径落盘——`onCreated` 的 `createCore` + `appendCore`，或无主认领的后缀写入。因此监听 firehose 的消费方永远看不到这条边界，必须从日志中读取它。
+
+对 seam 的影响：`load()` 仍是纯读取，没有 revision 递增，对平衡日志不走 `commitRepair`，被拒绝的 `append` 也不留下持久标记。但**接手不是纯读取**——如今一次拾起会在此前完全无写入的路径上产生写入，因此只读存储或磁盘写满会在 `session/created` 处报错，而不是在第一个真实轮次处。这是本放置方式新增的唯一成本，并且比加载路径方案的成本更窄（后者会让加载本身失败）。
+
+若崩溃发生在种子写入到达磁盘之前，边界会丢失，而这没有代价：待处理批次按序写入，所以丢掉一个边界意味着它之后的每个事件也一起丢掉。下一次接手读到的字节与上一次相同，会追加自己的边界，并对括号作出完全相同的判定。进程内消费方应优先使用 `firstLiveSeq`，它在任何写入之前就是精确的。
+
+## 保证的适用范围
+
+该谓词对*本*会话继承的括号成立，而不是关于其他写入方的存活信号。一个并发存活的会话可能在同一段存储历史上持有开放括号，而它自己的边界在别处。必须容忍并发写入方的消费方需要日志之外的存活信号，不能仅凭这个事件就省掉它。
+
+## Alternatives considered
+
+**由持久化协调器的冷加载路径写入边界。** 最先实现的方案，即 [`session/resumed` 边界](../../rejected/architecture/2026-07-29-session-resumed-log-boundary.md)，在合并前被放弃。它完全覆盖不到 fork，而 fork 恰恰是继承括号的所有方可能仍然存活的那一种情形。由于标记是在加载时铸造的，它还必须在读取路径上做持久写入，这把成本铺开到整个 seam：每次冷加载都递增 revision、对一份无需修复的平衡日志也要走 `commitRepair`、需要一个已存储时间下限来维持钳制的单调性，以及加载在只读存储上会失败。
+
+**在 loop 启动时追加边界。** loop 调用 `resumeWith`，因此覆盖恢复路径，但完全漏掉 `fork()` 与 `adopt()`，而且事件不得不在 `'startup'` 上触发——那是 fork 子会话发布的来源——于是 `SessionStartSource` 将不再具有区分力。它还会在追加标记之前就发布会话，因此 `session/created` 监听方可能观察到一份没有边界的带种子日志。
+
+**复用 `header.seedLength`。** 它是持久的 *fork 血缘*边界，并且刻意在恢复时保留原始 fork 取值——而恢复时构造种子是整份存储日志。这两个事实并不相同，混同会同时失去两者。
+
+**让崩溃修复连同轮次边界一起关闭 `compact/*`。** 否决：这会把每个插件的括号语义搬进核心的修复流程，而核心无法知道关闭另一个包的括号应该记录什么。
+
+## Consequences
+
+买到的：一条边界，在一处写入，对全部六条带种子启动路径都正确——包括持久化层方案触及不到的 fork 缺口。持久化各包保留纯读取路径。`firstLiveSeq` 获得一个持久孪生体，而不是关于同一边界的第二套彼此竞争的概念。
+
+代价：带种子会话的日志长了一个事件，这在九个包（session、agent-loop、持久化契约、jsonl、session-query、session-title、subagent-inprocess、telemetry、token-meter）里挪动了 seq 期望。其中两处更新是承重的而非机械的：telemetry 的收养测试现在断言该边界*会*被导出，因为它是本生命周期的自有写入；而属性测试套件的重放不变式被重述为"种子逐字节复现，外加一个仅日志边界"，并把幂等性补成一条独立属性。
+
+`session/end-seed` 加入了落盘词汇表。在预发布立场下（`SESSION_FORMAT_VERSION` 固定为 `0`，不作兼容承诺），更旧的日志只是没有它，而没有边界的日志会正确地判定没有任何内容属于构造种子历史。
+
+此处未做：还没有任何插件读取该边界。把压缩 seam 的陈旧性检查接到它上面，是催生这条边界的后续工作；谓词辅助函数应当归属那个 seam——在那里由真实消费方决定它的形状——而不是未经真实消费方检验就先落进核心。