Merge PR #941 dependency into manual compaction stack

# Conflicts:
#	docs/cordis-catalog/services.md
#	docs/core-data-structures/session.i18n.yaml
#	packages/host/apiproxy/README.i18n.yaml
#	packages/host/apiproxy/src/api-proxy.ts
#	packages/ui/tui/src/index.ts

.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

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+# 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。

.agents/notes/proposed/architecture/2026-07-29-durable-last-activity-index.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/proposed/architecture/2026-07-29-durable-last-activity-index.md
+2026-07-29-durable-last-activity-index.md: 0938e7ea2aa817818ed552fd8b702795840b547a
+2026-07-29-durable-last-activity-index.zh.md: 647bce817444c77ac3cd6f51385472fff745212f

.agents/notes/proposed/architecture/2026-07-29-durable-last-activity-index.md

@@ -0,0 +1,66 @@
+# Agent Note: Record last activity in the session index
+
+Status: proposed
+
+English | [中文](2026-07-29-durable-last-activity-index.zh.md)
+
+## Problem
+
+A cold (persisted, unattached) session has no stored answer to "when was this last worked in". `dsh-host-apiproxy`'s `summarizeCold()` therefore approximates it with the log file's mtime where one exists — `locate()` resolves a per-session artifact for JSONL and `undefined` for SQLite, whose cold sessions fall back to `createdAt` — and the web client sorts its session tree by the resulting `updatedAt`. The two backends are wrong in opposite directions: JSONL reads too new, SQLite too old.
+
+mtime answers a different question: when the artifact was last written. Every durable write refreshes it, including writes that are not activity — a truncate-repair of a torn tail, the synthetic closers that balance an interrupted turn, and the [`session/end-seed` boundary](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md) a seeded session appends. (A `flush` with nothing pending is not among them: the coordinator returns without reaching the backend.) The visible consequence is stable and wrong in one direction: a session touched without being worked in promotes itself above sessions the user actually worked in afterwards, and each touch re-promotes it. "Touched" is broader than "resumed" — `dsh-host-apiproxy`'s `agentFor()` resumes a cold session on first touch, and `sessions.history` reaches it when the web client merely opens one, so ordinary browsing is enough.
+
+The attached projection has a real fix — `lastActivityTime()` skips boundaries — but it needs the event log, and the cold path deliberately does not read one. Reading the log to compute `updatedAt` would defeat the header-only listing that keeps `list()` scaling with session count rather than log size.
+
+The [boundary change](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md) raised the frequency of this defect, because a pickup now writes where nothing was written before; `dsh-host-apiproxy`'s README records it under Known Limitations. It did not introduce the approximation, and removing the approximation is a durable-format decision, which is why it is scoped here rather than there.
+
+## Proposal
+
+Store last-activity time where a listing already reads — the session index — so `summarizeCold()` can serve it without opening the log. The coordinator computes the value, because it sees every append and already owns per-id state; backends persist it. That makes it a new `PersistenceBackend` contract element rather than backend-local bookkeeping, and keeps one definition of "activity" shared with the in-log `lastActivityTime()`.
+
+The two shipped backends have opposite constraints, and the proposal is deliberately asymmetric about them:
+
+- **SQLite** gets a column on `sessions`, written in the same transaction as `appendBatch`, at the cost of a monotonic `SCHEMA_VERSION` bump.
+- **JSONL cannot host a mutable header field.** The header is line 1, written once during materialization, and the log is opened for append forever after; `jsonl.spec.ts` pins that committed bytes are never rewritten. A per-append header field would violate an asserted durability invariant, not merely complicate the writer. A per-session sidecar file is the shape to compare against leaving JSONL approximate.
+
+Three questions must be answered before implementation, and none of them is settled here:
+
+**Which events count as activity?** `lastActivityTime()` answers this for the log by excluding `session/end-seed`. A stored field encodes the rule at write time, where the writer sees one batch rather than the whole log. The two must not drift, or the attached and cold surfaces will disagree about the same session.
+
+**How do pre-field logs behave?** Existing artifacts have no value. Falling back to mtime keeps them at today's accuracy; falling back to `createdAt` is honest but reorders every existing session in the picker and the tree.
+
+**Is a sidecar acceptable for JSONL?** It reintroduces a second file per session that can disagree with the log, which the single-artifact design avoided.
+
+## Alternatives considered
+
+**Read the log on the cold path.** Correct by construction and needs no format change, but it defeats the header-only listing: `list()` would scale with total log size, and the web session tree fans out over every session in the store. This is the option the mtime approximation exists to avoid.
+
+**Keep mtime and exclude boundary writes from it.** Rejected as impossible rather than undesirable: mtime is the filesystem's, not the backend's. Nothing short of restoring the timestamp after every boundary write would preserve it, and that races any concurrent reader and lies about the artifact.
+
+**Write the boundary only when repair occurred.** Would reduce the frequency, and the [boundary note](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md) already rejected it: the predicate must hold for an orderly restart too. Trading a correctness invariant for timestamp accuracy is the wrong direction.
+
+**Derive activity from a projection cache.** `session-projection-cache` already folds tails past a watermark, so a last-activity unit would ride existing machinery. Rejected as the primary shape because the cache is an optional composition entry; a listing served only when a cache plugin is mounted makes ordering depend on composition.
+
+## Acceptance criteria
+
+- `SessionSummary.updatedAt` for a cold session equals the same value the attached projection reports for that session, verified by resuming, quitting without a turn, and asserting the order is unchanged across both paths.
+- A resumed-then-abandoned session does not sort above a session worked in afterwards, in the web session tree and the TUI resume picker, pinned by an assembled snapshot rather than unit tests alone.
+- The activity rule has one definition: a test proves the stored field and `lastActivityTime()` agree over a log containing boundaries, closers, and a plain turn.
+- Pre-field artifacts load and list without error under the chosen fallback, with the fallback's ordering consequence asserted.
+- SQLite's `SCHEMA_VERSION` bump rejects the old on-disk version per the repo's no-migration stance.
+
+## Risks
+
+**Two definitions of activity drift.** The stored field is computed per batch, the projection over a whole log. A new event type classified one way at write time and the other at read time yields a session whose cold and attached orderings disagree — a bug that only appears after a restart, which is where it is hardest to notice.
+
+**A JSONL sidecar can disagree with its log.** A crash between the log append and the sidecar write leaves a stale value with no torn-tail marker to repair it. Every consumer would need to treat the sidecar as a hint, which is close to what mtime already is.
+
+**The fallback reorders existing sessions.** Whichever fallback is chosen, users with existing logs see their picker and tree reorder once on upgrade. `createdAt` makes that reordering large.
+
+**Cost may exceed the defect.** The defect is a misordering of abandoned sessions. If the honest answer for JSONL is "keep the approximation", this note's outcome may be documenting that decision rather than implementing a field — and that is an acceptable outcome.
+
+## Related
+
+- [The end-seed log boundary](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md) — one of the non-activity writes mtime counts; `dsh-session` owns `lastActivityTime()`, the in-log projection a stored field must agree with.
+- [Session persistence](../../implemented/architecture/2026-06-14-session-persistence.md) — the append-only and never-rewrite invariants that rule out a mutable JSONL header field.
+- [Shared persistence write coordinator](../../implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md) — the append path a stored field would hook into.

.agents/notes/proposed/architecture/2026-07-29-durable-last-activity-index.zh.md

@@ -0,0 +1,66 @@
+# Agent Note: 在会话索引中记录最后活动
+
+Status: proposed
+
+[English](2026-07-29-durable-last-activity-index.md) | 中文
+
+## 问题
+
+一个冷会话（已持久化、未附加）对「上次是什么时候在这里面工作过」没有任何已存储的答案。因此 `dsh-host-apiproxy` 的 `summarizeCold()` 在存在日志文件时用它的 mtime 来近似它——`locate()` 为 JSONL 解析出一个逐会话产物，为 SQLite 解析出 `undefined`，而 SQLite 的冷会话会回退到 `createdAt`——而 web 客户端就按由此得到的 `updatedAt` 为自己的会话树排序。这两个后端错的方向正好相反：JSONL 读出来偏新，SQLite 偏旧。
+
+mtime 回答的是另一个问题：这份产物上次是什么时候被写入的。每一次持久写入都会刷新它，包括那些并不是活动的写入：一次对撕裂尾部的截断修复、用来平衡被中断的轮次的那些合成 closer，以及带种子的会话会追加的 [`session/end-seed` 边界](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)。（没有待处理内容的 `flush` 不在其中：协调器在到达后端之前就返回了。）用户可见的后果是稳定的，而且只朝一个方向错：一个被触碰过却没有在里面工作过的会话，会把自己排到用户此后真正工作过的那些会话之前，而且每次触碰都会重新把它排上去一次。「触碰」比「恢复」的范围更宽——`dsh-host-apiproxy` 的 `agentFor()` 会在首次触碰时恢复一个冷会话，而 web 客户端仅仅打开一个会话时 `sessions.history` 就会到达它，因此普通的浏览就够了。
+
+已附加会话的那个投影有真正的修复办法（`lastActivityTime()` 会跳过边界），但它需要事件日志，而冷路径有意不去读日志。为计算 `updatedAt` 而读取日志，会让只读 header 的列举失去意义，而正是它让 `list()` 的开销随会话数量而非日志体量增长。
+
+[边界那次变更](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)提高了这个缺陷的出现频率，因为一次拾起如今会在此前完全无写入的路径上产生写入；`dsh-host-apiproxy` 的 README 已在 Known Limitations 中记录该项。它并没有引入这套近似做法，而移除这套近似是一项持久格式决策，因此它的范围划在本文，而不是那里。
+
+## 提案
+
+把最后活动时间存到列举本就会读取的地方，也就是会话索引，这样 `summarizeCold()` 无需打开日志就能给出答案。该值由协调器计算，因为它看得到每一次追加，而且本就拥有每 id 状态；由后端负责持久化。这样它就成为 `PersistenceBackend` 契约中新增的一个要素，而不是各后端本地的账目，同时让「活动」只保留一个定义，与日志内的 `lastActivityTime()` 共用。
+
+两个已交付的后端受到的约束正好相反，本提案对它们有意采取不对称的处理：
+
+- **SQLite** 在 `sessions` 表上得到一列，与 `appendBatch` 在同一个事务中写入，代价是一次单调的 `SCHEMA_VERSION` 递增。
+- **JSONL 无法承载一个可变的 header 字段。** header 就是第 1 行，在物化时一次写就，此后这份日志永远以追加方式打开；`jsonl.spec.ts` 钉住了「已提交的字节绝不重写」。一个每次追加都要改的 header 字段，违反的是一条被断言的持久性不变式，而不只是让写入方变复杂。要与「让 JSONL 保持近似」相比较的形态，是每会话一个伴随文件。
+
+实现之前必须回答三个问题，本文对它们都没有定论：
+
+**哪些事件算作活动？** 对日志而言，`lastActivityTime()` 通过排除 `session/end-seed` 回答了这个问题。一个已存储字段是在写入时编码这条规则的，而写入方在那里只看到一个批次，不是整份日志。两者不得发生漂移，否则已附加表层与冷表层会对同一个会话给出彼此矛盾的答案。
+
+**该字段引入之前的日志表现如何？** 既有产物里没有这个值。回退到 mtime 能让它们保持今天的准确度；回退到 `createdAt` 是诚实的，但会把选择器和会话树里每一个既有会话都重新排一次序。
+
+**对 JSONL 来说伴随文件可以接受吗？** 它重新引入了每会话第二个文件，而该文件可能与日志不一致，这正是单产物设计所避开的。
+
+## 考虑过的替代方案
+
+**在冷路径上读取日志。** 它按构造就是正确的，也不需要改动格式，但会让只读 header 的列举失去意义：`list()` 的开销将随日志总体量增长，而 web 会话树会扇出到存储中的每一个会话。mtime 近似的存在，正是为了避开这个选项。
+
+**保留 mtime，但把边界的写入排除在它之外。** 否决的理由是做不到，而不是不合意：mtime 属于文件系统，不属于后端。除了在每次边界写入之后把时间戳复原，没有别的办法能保住它，而那样做会与任何并发读取方产生竞态，也会对这份产物撒谎。
+
+**仅在确实发生了修复时才写入边界。** 这能降低出现频率，而[边界 Agent Note](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)已经否决过它：谓词对有序重启同样必须成立。用一条正确性不变式去换时间戳的准确度，方向是错的。
+
+**从投影缓存派生活动时间。** `session-projection-cache` 本就会折叠水位线之后的尾部，因此一个最后活动单元可以搭乘既有机制。它作为主形态被否决，因为该缓存是一个可选的组合项；只有挂载了缓存插件才提供的列举，会让排序取决于如何组合。
+
+## 验收标准
+
+- 冷会话的 `SessionSummary.updatedAt` 等于已附加会话的投影为同一个会话报告的那个值；验证方式是恢复、不跑轮次就退出，并断言两条路径上的顺序都没有变化。
+- 在 web 会话树和 TUI 恢复选择器中，一个恢复后即被弃置的会话不会排到此后工作过的会话之前；由一份组装后的快照钉住，而不是只靠单元测试。
+- 活动规则只有一个定义：一个测试证明，在一份同时包含边界、closer 和一个普通轮次的日志上，已存储字段与 `lastActivityTime()` 的结果一致。
+- 在选定的回退方案下，该字段引入之前的产物能够无错误地加载和列举，并且该回退在排序上的后果有断言覆盖。
+- 按本仓库不做迁移的立场，SQLite 的 `SCHEMA_VERSION` 递增会拒绝旧的磁盘版本。
+
+## 风险
+
+**「活动」的两个定义发生漂移。** 已存储字段按批次计算，而投影在整份日志上计算。一种新事件类型若在写入时按一种方式归类、在读取时按另一种方式归类，就会产生一个冷排序与已附加排序彼此矛盾的会话；这个缺陷只在重启之后才显现，而那正是最难被注意到的地方。
+
+**JSONL 的伴随文件可能与它的日志不一致。** 在日志追加与伴随文件写入之间发生崩溃，会留下一个陈旧的值，而且没有撕裂尾部标记可用来修复它。每个消费方都得把伴随文件当作一条提示来对待，而这与 mtime 今天的地位已经很接近了。
+
+**回退方案会让既有会话重新排序。** 无论选定哪种回退，持有既有日志的用户都会在升级时看到自己的选择器和会话树重新排一次序。选 `createdAt` 会让这次重排的幅度很大。
+
+**代价可能超过这个缺陷本身。** 该缺陷是被弃置会话的排序出错。如果对 JSONL 来说诚实的答案是「保留这套近似」，那么本文的结局可能是记录下这个决定，而不是实现一个字段，而这也是一个可以接受的结局。
+
+## 相关
+
+- [种子结束日志边界](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)——mtime 会计入的非活动写入之一；`dsh-session` 拥有 `lastActivityTime()`，也就是一个已存储字段必须与之保持一致的那个日志内投影。
+- [会话持久化](../../implemented/architecture/2026-06-14-session-persistence.md)——仅追加与绝不重写这两条不变式，正是它们排除了可变的 JSONL header 字段。
+- [共享持久化写入协调器](../../implemented/architecture/2026-06-18-shared-persistence-write-coordinator.md)——一个已存储字段将挂入的那条追加路径。

.agents/notes/rejected/architecture/2026-07-29-session-resumed-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/rejected/architecture/2026-07-29-session-resumed-log-boundary.md
+2026-07-29-session-resumed-log-boundary.md: 877b0c780f4c92983d2762243fac4e26d945887a
+2026-07-29-session-resumed-log-boundary.zh.md: a6f6ecc0d3f3a349f1a438eec0a84f27f8f649b2

.agents/notes/rejected/architecture/2026-07-29-session-resumed-log-boundary.md

@@ -0,0 +1,51 @@
+# Agent Note: Record the resume process boundary in the session log
+
+Status: rejected — the boundary belongs at the seeded-`Session` constructor, which also covers fork and replay; superseded by [the end-seed boundary](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)
+
+English | [中文](2026-07-29-session-resumed-log-boundary.zh.md)
+
+## Problem
+
+A session's durable log gave no evidence that it had changed processes. `session/created`, `session/disposed`, and `session/flush` are cordis runtime signals rather than `SessionEventMap` members, and `agent/session-start` carries a `SessionStartSource` but is emit-only and never logged. Reading a stored log therefore gave no hint that anything had been resumed.
+
+That gap makes one class of question unanswerable. A plugin that owns a standalone open/close pair in the log — compaction's `compact/start` … `compact/end` is the only one today — must distinguish an unmatched opening marker left by a process that died mid-operation from one an operation is holding right now. Those two states are **byte-identical in stored history**. Without a boundary the owner has to choose between refusing forever (an unmatched marker wedges the operation permanently, and because automatic compaction failure is warn-and-continue the user-visible result is that compaction silently stops working until the context window overflows) and proceeding always (which defeats the point of holding a lock).
+
+The pressure to fix this is immediate: moving `compact/start` to its real time point, before summarization, widens the crash window from a few microseconds of synchronous appends to the length of a whole model call, so orphaned brackets go from rare to routine.
+
+## Proposal
+
+`@deepseek-ai/dsh-session-persistence` declares one log-only `session/resumed` with an empty payload and appends exactly one at the end of every cold load, in the same `commitRepair` batch as any crash-repair closers and positioned after them — so every event before the boundary has a smaller seq and was written by a writer that is no longer tracking this log. Ownership lands narrowly on `loadCore()`, the cold-load path reached by `load()` and by `adopt()`. `loadLiveSnapshot()` appends nothing, and the non-mutating `inspect()`/`readFrom()` reads never write one.
+
+The predicate a bracket owner evaluates is purely a function of the log: an unmatched opening marker with a `session/resumed` after it is stale, and one with no `session/resumed` after it is live.
+
+`time` is `Date.now()` floored at the log's greatest `time`, deliberately unlike the synthetic closers, which reuse the last real event's timestamp so repair output stays a deterministic function of stored history. The wall clock is not monotonic — an NTP step, a VM restore, or a log copied from a machine that was ahead can put it behind events already stored — so the floor keeps every cross-boundary duration non-negative. The floor is durable, because the clamped boundary is stored and joins the log's maximum: one future-dated event pins every later boundary in that log to the same instant until wall time passes it.
+
+**The predicate distinguishes process succession, not concurrent writers.** `load()`'s liveness guard is `ctx.sessions.get(id)`, which only sees sessions live in *this* runtime, and no backend takes a cross-process per-session lock. So process B cold-loading a session A currently owns writes a boundary after A's still-open bracket. A consumer that must tolerate concurrent writers still needs a liveness signal beyond the log.
+
+## Why this was rejected
+
+Two reasons, found while reviewing where the marker belonged.
+
+**It covers no fork.** `sessions.fork()` and a subagent fork child construct a seeded session without touching persistence, so neither gets a boundary. A forked child inherits its parent's prefix verbatim — including an open `compact/start` the parent is still holding — which is the one case where the inherited bracket's owner is demonstrably alive. The predicate was unavailable exactly where it was most needed.
+
+**Minting the marker at load made a read path a durable write.** Every consequence the review surfaced traced to that: a revision bump on every cold load, a `commitRepair` batch on a balanced log with nothing to repair, the durable time floor above, a load that fails against a read-only store, and a marked log after a resume the caller then cancelled. None of these are wrong given the placement; they are the placement's cost.
+
+The successor keeps the problem statement and the concurrent-writer scope limit unchanged, and moves the write to `Session`'s constructor — the single waist all six seeded-start paths pass through, fork included. Because the marker then rides the ordinary seed-persistence path, the whole durable-write surface above disappears.
+
+## Alternatives considered
+
+**Use `Session.firstLiveSeq` as the staleness predicate.** Dismissed here on the grounds that it is documented as deliberately not persisted, so the same stored log yields different answers in different processes and a read-only reader cannot evaluate it at all. That reasoning was sound about the field and wrong about the conclusion: the fix is to persist a projection of it rather than to compute the boundary somewhere else. This is the alternative that became the successor.
+
+**Declare the event in core (`dsh-session`).** Rejected here because "the constructor cannot distinguish resume from fork or replay." That is true and turned out not to matter — the distinction is not needed, since inherited history is dead history in all three cases.
+
+**Teach `interruptedTurnClosers` to close `compact/*`.** Rejected: `compact/*` is plugin-owned vocabulary and core must not know it. Core closes turn, step, and tool boundaries — the relations it owns. The successor keeps this rejection.
+
+**Lazy self-repair: the owner appends a synthetic closing marker when it finds an orphan.** A write inside a read-shaped check, and it needs an invariant exception for a numbered owner whose turn has already closed.
+
+**A merge-extensible repair-contributor registry in core.** The right shape once a second consumer exists; with one consumer today, `packages/AGENTS.md` says not to split a seam preemptively.
+
+**Write the boundary only when repair actually occurred.** Rejected: the predicate must hold for an orderly restart too, where there is nothing to repair. The successor keeps this rejection.
+
+## Related
+
+The cold-session `updatedAt` skew this proposal documented is scoped in [the last-activity-index Agent Note](../../proposed/architecture/2026-07-29-durable-last-activity-index.md). That defect predates this proposal and survives its rejection: it is caused by mtime counting every durable write, not by any one boundary.

.agents/notes/rejected/architecture/2026-07-29-session-resumed-log-boundary.zh.md

@@ -0,0 +1,51 @@
+# Agent Note: 在会话日志中记录恢复的进程边界
+
+Status: rejected — 边界应当落在带种子 `Session` 的构造函数上，那里同时覆盖 fork 与回放；由[种子结束边界](../../implemented/architecture/2026-07-30-session-end-seed-log-boundary.md)取代
+
+[English](2026-07-29-session-resumed-log-boundary.md) | 中文
+
+## Problem
+
+会话的持久日志此前无法证明它换过进程。`session/created`、`session/disposed` 和 `session/flush` 是 cordis 运行时信号，而不是 `SessionEventMap` 成员；`agent/session-start` 虽然携带 `SessionStartSource`，却只用于 emit，从不记录。因此，读取一份已存储日志得不到任何关于「曾经发生过恢复」的线索。
+
+这一空缺让一类问题无法回答。在日志中拥有独立开始／结束事件对的插件必须区分两种未匹配的起始标记：一种由某个在操作中途死亡的进程留下，另一种正被当前某项操作持有；今天符合这一形态的只有压缩的 `compact/start` … `compact/end`。这两种状态**在已存储历史中逐字节相同**。没有边界，所有方只能在两种做法之间选择：永远拒绝（一个未匹配的标记会永久卡住该操作，而自动压缩失败采取警告并继续的策略，因此用户可见的结果是压缩静默停止工作，直到上下文窗口溢出），或者始终继续（这让持有锁失去了意义）。
+
+修复它的压力是即刻的：把 `compact/start` 移到摘要生成之前这个真实的时间点，会把崩溃窗口从几微秒的同步追加扩大为一整次模型调用的时长，孤儿括号也就从罕见变为常态。
+
+## Proposal
+
+`@deepseek-ai/dsh-session-persistence` 声明唯一一个纯日志事件 `session/resumed`，其载荷为空，并在每次冷加载结束时恰好追加一条：与崩溃修复产生的 closers 同处一个 `commitRepair` 批次，且排在它们之后。因此，该边界之前的每个事件都有更小的 seq，并且都是由一个不再追踪这份日志的写入方写下的。所有权狭窄地落在 `loadCore()`，也就是 `load()` 与 `adopt()` 到达的冷加载路径。`loadLiveSnapshot()` 不追加任何内容，非变更性的 `inspect()`／`readFrom()` 读取也从不写入。
+
+括号所有方求值的谓词纯粹是日志的函数：未匹配的起始标记之后有 `session/resumed` 的就是陈旧的，之后没有的就是存活的。
+
+`time` 取 `Date.now()` 并以日志的最大 `time` 为下限，刻意区别于合成 closers——后者复用最后一个真实事件的时间戳，以便修复输出始终是已存储历史的确定性函数。挂钟并非单调：一次 NTP 跳变、一次虚拟机恢复，或一份从走快的机器上拷来的日志，都可能让它落在已存储事件之后，因此这个下限让跨边界的时长都非负。该下限是持久的，因为被钳制的边界本身会被存储并加入日志的最大值：一个未来时间的事件会把该日志中之后的每个边界都钉在同一时刻，直到挂钟时间越过它。
+
+**该谓词区分的是进程接替，不是并发写入方。** `load()` 的存活性守卫是 `ctx.sessions.get(id)`，它只看到*本*运行时中存活的会话，而且没有任何后端会取跨进程的按会话锁。因此，进程 B 冷加载一个 A 当前拥有的会话时，会在 A 仍然开放的括号之后写入一个边界。必须容忍并发写入方的消费方仍然需要日志之外的存活信号。
+
+## 为什么被否决
+
+两个原因，都是在复审标记应当落在何处时发现的。
+
+**它完全覆盖不到 fork。** `sessions.fork()` 与子代理 fork 子会话在不触及持久化的情况下构造带种子会话，因此两者都拿不到边界。fork 子会话会逐字节继承父会话的前缀——包括父会话仍然持有的开放 `compact/start`——而这恰恰是继承括号的所有方明显还活着的唯一情形。谓词偏偏在最需要它的地方不可用。
+
+**在加载时铸造标记，把读取路径变成了持久写入。** 复审暴露出的每一项后果都源于此：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`、上文那个持久时间下限、加载在只读存储上会失败，以及调用方随后取消的恢复也已留下标记。这些在该放置方式下都不算错，它们就是该放置方式的成本。
+
+取代方案保留问题陈述与并发写入方的适用范围限制不变，并把写入移到 `Session` 的构造函数——全部六条带种子启动路径（含 fork）必经的唯一收窄处。由于标记随后走普通的种子持久化路径，上述整个持久写入面就消失了。
+
+## Alternatives considered
+
+**用 `Session.firstLiveSeq` 作为陈旧性谓词。** 此处以「文档明确它有意不做持久化，因此同一份已存储日志在不同进程中会给出不同答案，而只读读取方根本无法对它求值」为理由否决。这个推理对字段本身是成立的，但结论错了：正确的修法是持久化它的一个投影，而不是把边界挪到别处去算。这条替代方案正是后来的取代方案。
+
+**在核心（`dsh-session`）中声明该事件。** 此处以「构造函数无法把恢复与 fork 或回放区分开」为理由否决。这句话是对的，但事实证明它无关紧要——并不需要这种区分，因为在这三种情形下继承历史都是死历史。
+
+**教 `interruptedTurnClosers` 关闭 `compact/*`。** 否决：`compact/*` 是插件所属词汇，核心不得知道它。核心只关闭轮次、步骤和工具边界，也就是它自己拥有的关系。取代方案保留这条否决。
+
+**惰性自修复：所有方发现孤儿时自行追加一条合成的关闭标记。** 这是在一次形似读取的检查中执行写入，而且需要为一个带轮次编号、其轮次却已经关闭的所有方开一个不变式例外。
+
+**在核心中建一个可合并扩展的修复贡献方注册表。** 一旦出现第二个消费方，这就是正确的形状；今天只有一个消费方，而 `packages/AGENTS.md` 要求不要预先拆分 seam。
+
+**仅在确实发生了修复时才写入边界。** 否决：该谓词对有序重启同样必须成立，而那时没有任何东西需要修复。取代方案保留这条否决。
+
+## 相关
+
+本提案记录过的冷会话 `updatedAt` 偏斜，范围界定在[最后活动索引 Agent Note](../../proposed/architecture/2026-07-29-durable-last-activity-index.md)。该缺陷早于本提案存在，并且在本提案被否决后依然存在：它的成因是 mtime 会计入每一次持久写入，而不是某一个边界。

apps/web/tests/live-interactions.e2e.ts

@@ -167,6 +167,9 @@ describe('web e2e: live-turn interactions (cancel / error / retry)', () => {
     // "no crash, composer recovers, turn logged as error".
     await expect.poll(() => page.locator('textarea').first().isEnabled(), { timeout: 10_000 }).toBe(true)
     expect(await page.locator('[data-streaming="true"]').count()).toBe(0)
+    // The blank workspace also has an enabled composer. Wait for the driven
+    // session's only visible message before capturing its no-error-copy state.
+    await expect.poll(() => page.getByText(PROMPT, { exact: true }).first().isVisible(), { timeout: 10_000 }).toBe(true)
     // Golden of the same gap: the prompt bubble alone, no error copy in the
     // tree — the diff that changes when web-error-surface lands.
     const snapshot = await captureStableAria(page, '[class*="centerCol"]', scaffold!.workspaceCwd)

docs/cordis-catalog/services.md

@@ -1590,7 +1590,7 @@ fork(source: SessionForkSource, boundary?: number, childSessionId?: SessionId):
 
 Types: [CreateSessionOptions](../core-data-structures/persistence.md) · [Session](../core-data-structures/session.md) · [SessionId](../core-data-structures/core.md)
 
-Source: [`packages/core/session/src/index.ts:696`](../../packages/core/session/src/index.ts)
+Source: [`packages/core/session/src/index.ts:714`](../../packages/core/session/src/index.ts)
 
 ## `ctx.sessionTitle` — `SessionTitleService`
 
@@ -2197,7 +2197,7 @@ The concrete provider retains pi-tui, focus, and terminal lifecycle state. Plugi
 abstract openOverlay(request: TuiOverlayRequest): TuiOverlaySession
 ```
 
-Source: [`packages/ui/tui/src/index.ts:248`](../../packages/ui/tui/src/index.ts)
+Source: [`packages/ui/tui/src/index.ts:249`](../../packages/ui/tui/src/index.ts)
 
 ## `ctx.typert` — `TypertRegistry`
 

docs/core-data-structures/session.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 docs/core-data-structures/session.md
-session.md: 0c89f69ec0ccb893bb785e4f717cfd8ccb754514
-session.zh.md: 7c966ee2c779954d863b53c45e29be28458e675f
+session.md: 5389c2e2114094df5afdca25afd904b2cbbf8270
+session.zh.md: 29c4853213dfc886155e3f8d0991fa161e05c71a

docs/core-data-structures/session.md

@@ -91,6 +91,29 @@ interface SessionEventMap {
    * It is log-only; the latest snapshot reconstructs the request header.
    */
   'request/header': { header: EpochHeader; reason: RequestHeaderReason }
+  /**
+   * Marks the end of a constructor seed. Events before it have smaller seq
+   * values and came from the seed (resume, fork, or replay); this lifecycle
+   * produced none of them. This log-only event is the durable projection of
+   * {@link Session.firstLiveSeq}. Its payload is empty — position and `time`
+   * carry the meaning.
+   *
+   * Locate the LAST one in stored history. A seed already ending in one is not
+   * re-marked, so reopening an untouched session does not grow its log per
+   * pickup and the event need not be at the current `firstLiveSeq`.
+   *
+   * `Session`'s constructor is the only legitimate writer. The invariant
+   * companion deliberately constrains nothing here, so a plugin appending one
+   * would silently classify every live bracket before it as seed history.
+   *
+   * An owner of a standalone open/close bracket (`compact/start` …
+   * `compact/end`) reads it because seed history and live work are otherwise
+   * byte-identical: an unmatched opening marker before this event belongs to
+   * an ended lifecycle, whatever ended it. NOT a liveness signal about other
+   * writers — a concurrently live session holds its own boundary elsewhere,
+   * so tolerating concurrent writers needs a signal beyond the log.
+   */
+  'session/end-seed': Record<string, never>
 }
 ```
 
@@ -320,14 +343,25 @@ declare class Session {
   get id(): SessionId;
   /**
    * The first seq appended IN THIS PROCESS: the length of the constructor
-   * seed (0 without one). Events below it entered through construction —
-   * replay, fork, or resume — and were never published on the `session/event`
-   * firehose (constructor seeds do not emit), so consumers that replay the
-   * log as a publication substitute (telemetry adoption) start here. Distinct
-   * from `header.seedLength`, the DURABLE fork-lineage boundary: a resumed
-   * session's constructor seed is its full stored log, while its header keeps
-   * the original fork value — this field is the in-process construction fact
-   * and is deliberately not persisted.
+   * seed (0 without one). Events with smaller seq values entered through
+   * construction — replay, fork, or resume — and were never published on the
+   * `session/event` firehose (constructor seeds do not emit), so consumers
+   * that replay the log as a publication substitute (telemetry adoption)
+   * start here. Distinct from `header.seedLength`, the DURABLE fork-lineage
+   * boundary: a resumed session's constructor seed is its full stored log,
+   * while its header keeps the original fork value — this field is the
+   * in-process construction fact.
+   *
+   * Not persisted itself: a seeded session projects it into the log as the
+   * `session/end-seed` event, which is what a consumer reading STORED history
+   * reads. Locate the LAST such event, not necessarily one at this seq — a
+   * seed already ending in one is not re-marked, so reopening an untouched
+   * session leaves that event at a smaller seq than `firstLiveSeq`. Prefer
+   * this field in-process: it is exact before the marker reaches storage.
+   *
+   * When this lifecycle appends the marker, it occupies this seq before the
+   * store attaches and therefore does not publish either. Otherwise this seq
+   * holds an ordinary published write.
    */
   readonly firstLiveSeq: number;
   constructor(id: SessionId, seed?: readonly SessionEvent[], header?: SessionHeader);
@@ -508,6 +542,16 @@ A turn encloses one model-loop execution, not the whole session log. Idle inject
 
 The optional `dsh-session/invariant` companion enforces the relations owned by core: turn and step numbering, execution-event enclosure, and same-step tool call/result pairing. Merge-extensible event relations belong to the plugin that declares them, so core does not reject an unknown event merely because no turn is open. See [the standalone-event decision](../../.agents/notes/implemented/simplification/2026-07-28-remove-synthetic-log-only-turns.md).
 
+## The end-seed boundary: `session/end-seed`
+
+A seeded session — resume, fork, or replay — appends this log-only event immediately after its constructor seed, as its first live write. Events before it have smaller seq values and came from the seed. It is the durable projection of `firstLiveSeq`: that field answers where this lifecycle's writes start for a consumer holding the object, while the event answers the same question for one holding only stored bytes. The payload is empty, so position and `time` carry the whole meaning, and it produces no message. `Session`'s constructor is the only legitimate writer.
+
+An empty seed writes nothing, and a seed already ending in `session/end-seed` is not re-marked, so reopening an untouched session does not grow its log per pickup. Locate the LAST `session/end-seed` in stored history rather than assuming one exists at `firstLiveSeq`: after a pickup with no work, the event has a smaller seq than the next lifecycle's `firstLiveSeq`.
+
+It exists because seed history and live work are otherwise byte-identical, which defeats any plugin owning a standalone open/close bracket: an unmatched `compact/start` reads the same whether the writer crashed mid-compaction or is compacting right now. An opening marker before `session/end-seed` came from the constructor seed and belongs to an ended lifecycle, whatever ended it (a crash, a succeeding process, or a fork out of a still-running parent), so its owner may treat it as dead. That covers only brackets *this* session inherited: a concurrently live session holding an open bracket over the same history has its own boundary elsewhere, so tolerating concurrent writers needs a liveness signal beyond the log. Core writes the boundary and reads nothing from it — a bracket's vocabulary stays with its owning plugin, which is why crash repair closes turn/step/tool boundaries and never `compact/*`.
+
+Activity ordering excludes the boundary through `lastActivityTime(events)`: picking a session up is not work, and lazy resume means browsing writes one, so a resume picker or session list ordering by log tail would float every opened session to the top.
+
 ## Plugin-contributed log-only events
 
 A plugin may declaration-merge extra `SessionEventMap` types. These are **log-only**: NOT `SurfaceEventType`s (they carry no `surfaceOp` and contribute nothing to derived history). Their owner decides whether they belong to an open execution turn or may stand between turns, and enforces any relation in its own invariant companion. The full per-event enumeration — core and plugin-contributed alike, with payloads and provenance — is the generated [persistence log event catalog](../persistence-catalog.md); the compaction seam's `compact/*` semantics are discussed on [compaction.md](compaction.md).

docs/core-data-structures/session.zh.md

@@ -91,6 +91,29 @@ interface SessionEventMap {
    * It is log-only; the latest snapshot reconstructs the request header.
    */
   'request/header': { header: EpochHeader; reason: RequestHeaderReason }
+  /**
+   * Marks the end of a constructor seed. Events before it have smaller seq
+   * values and came from the seed (resume, fork, or replay); this lifecycle
+   * produced none of them. This log-only event is the durable projection of
+   * {@link Session.firstLiveSeq}. Its payload is empty — position and `time`
+   * carry the meaning.
+   *
+   * Locate the LAST one in stored history. A seed already ending in one is not
+   * re-marked, so reopening an untouched session does not grow its log per
+   * pickup and the event need not be at the current `firstLiveSeq`.
+   *
+   * `Session`'s constructor is the only legitimate writer. The invariant
+   * companion deliberately constrains nothing here, so a plugin appending one
+   * would silently classify every live bracket before it as seed history.
+   *
+   * An owner of a standalone open/close bracket (`compact/start` …
+   * `compact/end`) reads it because seed history and live work are otherwise
+   * byte-identical: an unmatched opening marker before this event belongs to
+   * an ended lifecycle, whatever ended it. NOT a liveness signal about other
+   * writers — a concurrently live session holds its own boundary elsewhere,
+   * so tolerating concurrent writers needs a signal beyond the log.
+   */
+  'session/end-seed': Record<string, never>
 }
 ```
 
@@ -322,14 +345,25 @@ declare class Session {
   get id(): SessionId;
   /**
    * The first seq appended IN THIS PROCESS: the length of the constructor
-   * seed (0 without one). Events below it entered through construction —
-   * replay, fork, or resume — and were never published on the `session/event`
-   * firehose (constructor seeds do not emit), so consumers that replay the
-   * log as a publication substitute (telemetry adoption) start here. Distinct
-   * from `header.seedLength`, the DURABLE fork-lineage boundary: a resumed
-   * session's constructor seed is its full stored log, while its header keeps
-   * the original fork value — this field is the in-process construction fact
-   * and is deliberately not persisted.
+   * seed (0 without one). Events with smaller seq values entered through
+   * construction — replay, fork, or resume — and were never published on the
+   * `session/event` firehose (constructor seeds do not emit), so consumers
+   * that replay the log as a publication substitute (telemetry adoption)
+   * start here. Distinct from `header.seedLength`, the DURABLE fork-lineage
+   * boundary: a resumed session's constructor seed is its full stored log,
+   * while its header keeps the original fork value — this field is the
+   * in-process construction fact.
+   *
+   * Not persisted itself: a seeded session projects it into the log as the
+   * `session/end-seed` event, which is what a consumer reading STORED history
+   * reads. Locate the LAST such event, not necessarily one at this seq — a
+   * seed already ending in one is not re-marked, so reopening an untouched
+   * session leaves that event at a smaller seq than `firstLiveSeq`. Prefer
+   * this field in-process: it is exact before the marker reaches storage.
+   *
+   * When this lifecycle appends the marker, it occupies this seq before the
+   * store attaches and therefore does not publish either. Otherwise this seq
+   * holds an ordinary published write.
    */
   readonly firstLiveSeq: number;
   constructor(id: SessionId, seed?: readonly SessionEvent[], header?: SessionHeader);
@@ -512,6 +546,16 @@ interface TurnEndReasonMap {
 
 可选的 `dsh-session/invariant` 配套插件会强制核心拥有的关系：轮次与步骤编号、执行事件封闭，以及同一步骤内的工具调用／结果配对。可合并扩展事件的关系由声明它的插件拥有，因此核心不会仅因没有开放轮次就拒绝未知事件。见[独立事件决策](../../.agents/notes/implemented/simplification/2026-07-28-remove-synthetic-log-only-turns.md)。
 
+## 种子结束边界：`session/end-seed`
+
+带种子的会话（恢复、fork 或回放）紧接构造种子之后追加这个仅日志事件，作为自己的第一次实时写入。在它之前的事件具有更小的 seq，且来自种子。它是 `firstLiveSeq` 的持久投影：该字段为持有对象的消费方回答本生命周期的写入从哪里开始，该事件则为只持有存储字节的消费方回答同一问题。payload 为空，因此位置与 `time` 承载全部含义，且不产生任何消息。`Session` 的构造函数是唯一合法的写入方。
+
+空种子不写入任何内容；种子本身已以 `session/end-seed` 结尾时不会重复标记，因此重新打开一个未被改动的会话不会每次拾起都增长日志。应定位存储历史中的最后一条 `session/end-seed`，而不是假定 `firstLiveSeq` 处一定有一条：在一次没有产生工作的拾起之后，该事件的 seq 会小于下一个生命周期的 `firstLiveSeq`。
+
+它之所以必要，是因为种子历史与实时工作在字节层面完全相同，这会让任何拥有独立开／闭括号的插件失效：一个未配对的 `compact/start`，无论写入方是在压缩中途崩溃、还是此刻正在压缩，读起来都一样。在 `session/end-seed` 之前的开启标记来自构造种子，并且属于一个已结束的生命周期，无论结束原因为何（崩溃、进程接替，或从仍在运行的父会话 fork 出来），因此其所有方可以视之为已死。这只覆盖*本*会话继承的括号：另一个并发存活的会话可能在同一段历史上持有开放括号，而它自己的边界在别处，因此容忍并发写入方还需要日志之外的存活信号。核心写入该边界但不从中读取任何内容——括号的词汇表仍归其所属插件，这也正是崩溃修复只关闭轮次／步骤／工具边界而从不处理 `compact/*` 的原因。
+
+活动排序通过 `lastActivityTime(events)` 排除该边界：接手会话不算工作，而惰性恢复意味着浏览就会写入一个，因此按日志尾部排序的恢复选择器或会话列表会把每个打开过的会话顶到最前。
+
 ## 插件贡献的仅日志事件
 
 插件可以通过 declaration merging 添加额外的 `SessionEventMap` 类型。这些是**仅日志**事件：不是 `SurfaceEventType`（不携带 `surfaceOp`，不参与派生历史）。事件所有方决定它们属于一个开放的执行轮次，还是可以独立位于轮次之间，并在自己的不变量配套插件中强制所需关系。完整的逐事件枚举（核心与插件贡献的，含 payload 与溯源信息）见生成的[持久化日志事件目录](../persistence-catalog.md)；压缩 seam 的 `compact/*` 语义在 [compaction.md](compaction.md) 中讨论。

docs/persistence-catalog.md

@@ -78,7 +78,7 @@ export type SessionEvent<T extends SessionEventType = SessionEventType> = {
 }[T]
 ```
 
-Sources: [`packages/core/session/src/types.ts:256`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:263`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:292`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:324`](../packages/core/session/src/types.ts)
+Sources: [`packages/core/session/src/types.ts:279`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:286`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:315`](../packages/core/session/src/types.ts) · [`packages/core/session/src/types.ts:347`](../packages/core/session/src/types.ts)
 
 ## Events
 
@@ -404,6 +404,36 @@ Source: [`packages/sandbox/sandbox-policy/src/session-mode.ts:33`](../packages/s
 
 ### `session/*`
 
+#### `session/end-seed` — log-only
+
+```ts persistence-catalog
+/**
+ * Marks the end of a constructor seed. Events before it have smaller seq
+ * values and came from the seed (resume, fork, or replay); this lifecycle
+ * produced none of them. This log-only event is the durable projection of
+ * {@link Session.firstLiveSeq}. Its payload is empty — position and `time`
+ * carry the meaning.
+ *
+ * Locate the LAST one in stored history. A seed already ending in one is not
+ * re-marked, so reopening an untouched session does not grow its log per
+ * pickup and the event need not be at the current `firstLiveSeq`.
+ *
+ * `Session`'s constructor is the only legitimate writer. The invariant
+ * companion deliberately constrains nothing here, so a plugin appending one
+ * would silently classify every live bracket before it as seed history.
+ *
+ * An owner of a standalone open/close bracket (`compact/start` …
+ * `compact/end`) reads it because seed history and live work are otherwise
+ * byte-identical: an unmatched opening marker before this event belongs to
+ * an ended lifecycle, whatever ended it. NOT a liveness signal about other
+ * writers — a concurrently live session holds its own boundary elsewhere,
+ * so tolerating concurrent writers needs a signal beyond the log.
+ */
+'session/end-seed': Record<string, never>
+```
+
+Source: [`packages/core/session/src/types.ts:275`](../packages/core/session/src/types.ts)
+
 #### `session/title` — log-only
 
 ```ts persistence-catalog

examples/acp-agent/tests/snapshots/subagent-fork/session.1.jsonl

@@ -1,6 +1,6 @@
 {"type":"session","version":0,"id":"ada8966c-9fa3-441b-8721-37ff1e795e6a","createdAt":1783352137161,"cwd":"{{cwd}}","parentSession":"96cf59c9-b347-48b9-b234-a5200913ad05","seedLength":38,"delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352134837,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
-{"type":"user/message","seq":1,"time":1783352134838,"data":{"content":[{"type":"text","text":"Remember this fact for later: the project codeword is MARMALADE. Reply with the single word OK and stop. Do not use any tools."}],"source":{"kind":"user"},"role":"user","id":"917c2f1a-be80-4f54-86e8-c94fe6859bdd"},"surfaceOp":"append"}
+{"type":"user/message","seq":1,"time":1783352134838,"data":{"content":[{"type":"text","text":"Remember this fact for later: the project codeword is MARMALADE. Reply with the single word OK and stop. Do not use any tools."}],"source":{"kind":"user"},"role":"user","id":"ecede90b-f918-4b3c-81cc-aefcc375d269"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352134838,"data":{"title":"Remember this fact for later:","messageSeqs":[1],"source":{"kind":"fallback"}}}
 {"type":"step/start","seq":3,"time":1783352134840,"data":{"turn":1,"step":1}}
 {"type":"request/header","seq":4,"time":1783352134840,"data":{"header":{"config":{"provider":"deepseek","model":"deepseek-v4-flash"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}
@@ -12,21 +12,22 @@
 {"type":"assistant/chunk","seq":32,"time":1783352135771,"data":{"turn":1,"step":1,"chunk":{"type":"block-end","index":1,"block":{"type":"text","text":"OK"}}}}
 {"type":"assistant/chunk","seq":33,"time":1783352135771,"data":{"turn":1,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":2885,"outputTokens":25,"cacheReadTokens":0,"reasoningTokens":23}}}}
 {"type":"assistant/chunk","seq":34,"time":1783352135771,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}
-{"type":"assistant/message","seq":35,"time":1783352135773,"data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"reasoning","text":"The user wants me to remember the codeword \"MARMALADE\" and reply with just \"OK\"."},{"type":"text","text":"OK"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"5927ef74-0269-4474-a6c0-45c09c1adac5"},"usage":{"inputTokens":2885,"outputTokens":25,"cacheReadTokens":0,"reasoningTokens":23}},"sourceEventSeqs":[5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34],"surfaceOp":"append"}
+{"type":"assistant/message","seq":35,"time":1783352135773,"data":{"turn":1,"step":1,"message":{"role":"assistant","content":[{"type":"reasoning","text":"The user wants me to remember the codeword \"MARMALADE\" and reply with just \"OK\"."},{"type":"text","text":"OK"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"d6c3a4bf-20e0-459f-9bc9-945f6650b5f1"},"usage":{"inputTokens":2885,"outputTokens":25,"cacheReadTokens":0,"reasoningTokens":23}},"sourceEventSeqs":[5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34],"surfaceOp":"append"}
 {"type":"step/end","seq":36,"time":1783352135773,"data":{"turn":1,"step":1}}
 {"type":"turn/end","seq":37,"time":1783352135773,"data":{"turn":1,"reason":{"kind":"completed"}}}
-{"type":"turn/start","seq":38,"time":1783352137162,"data":{"turn":2,"trigger":{"kind":"message","source":{"kind":"user"}}}}
-{"type":"user/message","seq":39,"time":1783352137163,"data":{"content":[{"type":"text","text":"What is the project codeword mentioned earlier in this conversation? Reply with exactly that one word and nothing else."}],"source":{"kind":"user"},"role":"user","id":"840f1fca-2577-47c1-acee-c47125098882"},"surfaceOp":"append"}
-{"type":"step/start","seq":40,"time":1783352137163,"data":{"turn":2,"step":1}}
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examples/acp-agent/tests/snapshots/subagent-mixed/session.2.jsonl

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examples/headless-agent/tests/semantic-checkpoint-snapshots/tool-outcome-unknown/session.expected.jsonl

@@ -7,15 +7,16 @@
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examples/headless-agent/tests/subagent-inheritance-snapshots/parent-override/parent.expected.jsonl

@@ -3,26 +3,27 @@
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-{"type":"assistant/chunk","seq":9,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
-{"type":"assistant/chunk","seq":10,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"tool-call-delta","index":0,"id":"delegate-write","name":"subagent","argumentsDelta":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}}
-{"type":"assistant/chunk","seq":11,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}}}
-{"type":"assistant/chunk","seq":12,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
-{"type":"assistant/chunk","seq":13,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
-{"type":"assistant/message","seq":14,"time":0,"data":{"turn":2,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[9,10,11,12,13],"surfaceOp":"append"}
-{"type":"tool/call","seq":15,"time":0,"data":{"turn":2,"step":1,"callId":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}
-{"type":"tool/result","seq":16,"time":0,"data":{"turn":2,"step":1,"message":{"source":{"kind":"tool","callId":"delegate-write"},"content":[{"type":"tool-result","toolCallId":"delegate-write","content":[{"type":"text","text":"CHILD_DENIED [sandbox: file access denied under read-only mode]"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[15],"surfaceOp":"append"}
-{"type":"step/end","seq":17,"time":0,"data":{"turn":2,"step":1}}
-{"type":"step/start","seq":18,"time":0,"data":{"turn":2,"step":2}}
-{"type":"assistant/chunk","seq":19,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}
-{"type":"assistant/chunk","seq":20,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"text-delta","index":0,"text":"The delegated child was denied by the sandbox. PARENT_DONE"}}}
-{"type":"assistant/chunk","seq":21,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"The delegated child was denied by the sandbox. PARENT_DONE"}}}}
-{"type":"assistant/chunk","seq":22,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
-{"type":"assistant/chunk","seq":23,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}
-{"type":"assistant/message","seq":24,"time":0,"data":{"turn":2,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"The delegated child was denied by the sandbox. PARENT_DONE"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[19,20,21,22,23],"surfaceOp":"append"}
-{"type":"step/end","seq":25,"time":0,"data":{"turn":2,"step":2}}
-{"type":"turn/end","seq":26,"time":0,"data":{"turn":2,"reason":{"kind":"completed"}}}
+{"type":"session/end-seed","seq":4,"time":0,"data":{}}
+{"type":"turn/start","seq":5,"time":0,"data":{"turn":2,"trigger":{"kind":"message","source":{"kind":"user"}}}}
+{"type":"user/message","seq":6,"time":0,"data":{"content":[{"type":"text","text":"Delegate the write probe to a subagent."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}
+{"type":"session/title","seq":7,"time":0,"data":{"title":"Tighten this session to read-only.","messageSeqs":[1],"source":{"kind":"fallback"}}}
+{"type":"step/start","seq":8,"time":0,"data":{"turn":2,"step":1}}
+{"type":"request/header","seq":9,"time":0,"data":{"header":{"config":{"provider":"deepseek","model":"deepseek-v4-flash"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}
+{"type":"assistant/chunk","seq":10,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"tool-call"}}}
+{"type":"assistant/chunk","seq":11,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"tool-call-delta","index":0,"id":"delegate-write","name":"subagent","argumentsDelta":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}}
+{"type":"assistant/chunk","seq":12,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"block-end","index":0,"block":{"type":"tool-call","id":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}}}
+{"type":"assistant/chunk","seq":13,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
+{"type":"assistant/chunk","seq":14,"time":0,"data":{"turn":2,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
+{"type":"assistant/message","seq":15,"time":0,"data":{"turn":2,"step":1,"message":{"role":"assistant","content":[{"type":"tool-call","id":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[10,11,12,13,14],"surfaceOp":"append"}
+{"type":"tool/call","seq":16,"time":0,"data":{"turn":2,"step":1,"callId":"delegate-write","name":"subagent","arguments":"{\"description\": \"Delegated write probe\", \"prompt\": \"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE.\"}"}}
+{"type":"tool/result","seq":17,"time":0,"data":{"turn":2,"step":1,"message":{"source":{"kind":"tool","callId":"delegate-write"},"content":[{"type":"tool-result","toolCallId":"delegate-write","content":[{"type":"text","text":"CHILD_DENIED [sandbox: file access denied under read-only mode]"}],"isError":false}],"role":"user","id":"{{sessionId}}"}},"sourceEventSeqs":[16],"surfaceOp":"append"}
+{"type":"step/end","seq":18,"time":0,"data":{"turn":2,"step":1}}
+{"type":"step/start","seq":19,"time":0,"data":{"turn":2,"step":2}}
+{"type":"assistant/chunk","seq":20,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}
+{"type":"assistant/chunk","seq":21,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"text-delta","index":0,"text":"The delegated child was denied by the sandbox. PARENT_DONE"}}}
+{"type":"assistant/chunk","seq":22,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"block-end","index":0,"block":{"type":"text","text":"The delegated child was denied by the sandbox. PARENT_DONE"}}}}
+{"type":"assistant/chunk","seq":23,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"usage","usage":{"inputTokens":10,"outputTokens":5}}}}
+{"type":"assistant/chunk","seq":24,"time":0,"data":{"turn":2,"step":2,"chunk":{"type":"finish","reason":{"kind":"stop"}}}}
+{"type":"assistant/message","seq":25,"time":0,"data":{"turn":2,"step":2,"message":{"role":"assistant","content":[{"type":"text","text":"The delegated child was denied by the sandbox. PARENT_DONE"}],"source":{"kind":"model","provider":"deepseek","model":"deepseek-v4-flash"},"id":"{{sessionId}}"},"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[20,21,22,23,24],"surfaceOp":"append"}
+{"type":"step/end","seq":26,"time":0,"data":{"turn":2,"step":2}}
+{"type":"turn/end","seq":27,"time":0,"data":{"turn":2,"reason":{"kind":"completed"}}}

packages/cordis/tool-cordis/src/api-catalog.ts

@@ -2177,7 +2177,7 @@ export const TYPE_API: readonly TypeApiEntry[] = [
   },
   {
     name: 'SessionEventMap',
-    declaration: 'export interface SessionEventMap {\n    \'turn/start\': {\n        turn: number;\n        trigger: TurnTrigger;\n    };\n    \'turn/end\': {\n        turn: number;\n        reason: TurnEndReason;\n    };\n    \'step/start\': {\n        turn: number;\n        step: number;\n    };\n    \'step/end\': {\n        turn: number;\n        step: number;\n    };\n    \'user/message\': UserMessage;\n    \'assistant/chunk\': {\n        turn: number;\n        step: number;\n        chunk: StreamChunk;\n    };\n    \'assistant/message\': {\n        turn: number;\n        step: number;\n        message: AssistantMessage;\n        usage?: TokenUsage;\n    };\n    \'tool/call\': {\n        turn: number;\n        step: number;\n        callId: CallId;\n        name: string;\n        arguments: string;\n    };\n    \'tool/result\': {\n        turn: number;\n        step: number;\n        message: ToolResultMessage;\n        error?: {\n            name: string;\n            code: string;\n        };\n        meta?: JsonValue;\n    };\n    \'steering/message\': {\n        turn: number;\n        message: UserMessage;\n    };\n    \'todo/write\': {\n        todos: TodoItem[];\n    };\n    \'request/header\': {\n        header: EpochHeader;\n        reason: RequestHeaderReason;\n    };\n}',
+    declaration: 'export interface SessionEventMap {\n    \'turn/start\': {\n        turn: number;\n        trigger: TurnTrigger;\n    };\n    \'turn/end\': {\n        turn: number;\n        reason: TurnEndReason;\n    };\n    \'step/start\': {\n        turn: number;\n        step: number;\n    };\n    \'step/end\': {\n        turn: number;\n        step: number;\n    };\n    \'user/message\': UserMessage;\n    \'assistant/chunk\': {\n        turn: number;\n        step: number;\n        chunk: StreamChunk;\n    };\n    \'assistant/message\': {\n        turn: number;\n        step: number;\n        message: AssistantMessage;\n        usage?: TokenUsage;\n    };\n    \'tool/call\': {\n        turn: number;\n        step: number;\n        callId: CallId;\n        name: string;\n        arguments: string;\n    };\n    \'tool/result\': {\n        turn: number;\n        step: number;\n        message: ToolResultMessage;\n        error?: {\n            name: string;\n            code: string;\n        };\n        meta?: JsonValue;\n    };\n    \'steering/message\': {\n        turn: number;\n        message: UserMessage;\n    };\n    \'todo/write\': {\n        todos: TodoItem[];\n    };\n    \'request/header\': {\n        header: EpochHeader;\n        reason: RequestHeaderReason;\n    };\n    \'session/end-seed\': Record<string, never>;\n}',
   },
   {
     name: 'SessionEventMetadataFilter',

packages/core/agent-loop/tests/loop.spec.ts

@@ -1221,8 +1221,9 @@ describe('agent loop', () => {
 
     const replayed = ctx.sessions.create(SessionId('replayed'), { seed: [...agent.session.events] })
     expect(replayed.deriveMessages()).toEqual(agent.session.deriveMessages())
-    // event-by-event identity of types
-    expect(replayed.events.map(e => e.type)).toEqual(
+    // event-by-event identity of types over the inherited prefix
+    expect(replayed.events.slice(0, agent.session.seq).map(e => e.type)).toEqual(
       agent.session.events.map(e => e.type))
+    expect(replayed.events.at(-1)?.type).toBe('session/end-seed')
   })
 })

packages/core/agent-loop/tests/resume.spec.ts

@@ -283,7 +283,8 @@ describe('the session-persistence Agent Note: AgentLoop factory create/resume',
       agentOptions: { provider: 'mock', model: 'mock' },
       setup: async (agentCtx) => {
         expect(agentCtx.agent?.id).toBe(sessionId)
-        expect(agentCtx.agent?.session.events).toHaveLength(2)
+        // The two persisted events plus the end-seed marker.
+        expect(agentCtx.agent?.session.events).toHaveLength(3)
         agentCtx.on('session/created', () => void order.push('setup-listener:session/created'))
         agentCtx.on('agent/created', () => void order.push('setup-listener:agent/created'))
         order.push('setup:start')
@@ -585,7 +586,10 @@ describe('the session-persistence Agent Note: AgentLoop factory create/resume',
     const a2 = (await ctx2.agents.resume({ resumeSessionId: SessionId('sess-resume') })).agent
     // The resumed session carries the prior history…
     expect(a2.session.id).toBe('sess-resume')
-    expect(a2.session.events.length).toBe(events1.length)
+    // …followed by one end-seed event marking the constructor seed.
+    expect(a2.session.events.length).toBe(events1.length + 1)
+    expect(a2.session.firstLiveSeq).toBe(events1.length)
+    expect(a2.session.events.at(-1)?.type).toBe('session/end-seed')
     const replay = new Session(SessionId('replay'), events1)
     expect(a2.session.deriveMessages()).toEqual(replay.deriveMessages())
 

packages/core/session/src/index.ts

@@ -23,7 +23,7 @@ export * from './types.ts'
 export type { AssistantMessage, ToolResultMessage, UserMessage } from '@deepseek-ai/dsh-llm'
 export { isJsonValue, snapshotJsonValue } from './json.ts'
 export type { JsonValue } from './json.ts'
-export { interruptedTurnClosers, TOOL_NOT_STARTED, TOOL_OUTCOME_UNKNOWN } from './repair.ts'
+export { interruptedTurnClosers, lastActivityTime, TOOL_NOT_STARTED, TOOL_OUTCOME_UNKNOWN } from './repair.ts'
 export { decodeStorageRecord, packChunkRuns } from './chunk-rows.ts'
 export type { ChunkRow, StorageRecord } from './chunk-rows.ts'
 export type { SessionSurface, SurfaceFoldReplacement, SurfaceFoldResult } from './surface.ts'
@@ -382,14 +382,25 @@ export class Session {
 
   /**
    * The first seq appended IN THIS PROCESS: the length of the constructor
-   * seed (0 without one). Events below it entered through construction —
-   * replay, fork, or resume — and were never published on the `session/event`
-   * firehose (constructor seeds do not emit), so consumers that replay the
-   * log as a publication substitute (telemetry adoption) start here. Distinct
-   * from `header.seedLength`, the DURABLE fork-lineage boundary: a resumed
-   * session's constructor seed is its full stored log, while its header keeps
-   * the original fork value — this field is the in-process construction fact
-   * and is deliberately not persisted.
+   * seed (0 without one). Events with smaller seq values entered through
+   * construction — replay, fork, or resume — and were never published on the
+   * `session/event` firehose (constructor seeds do not emit), so consumers
+   * that replay the log as a publication substitute (telemetry adoption)
+   * start here. Distinct from `header.seedLength`, the DURABLE fork-lineage
+   * boundary: a resumed session's constructor seed is its full stored log,
+   * while its header keeps the original fork value — this field is the
+   * in-process construction fact.
+   *
+   * Not persisted itself: a seeded session projects it into the log as the
+   * `session/end-seed` event, which is what a consumer reading STORED history
+   * reads. Locate the LAST such event, not necessarily one at this seq — a
+   * seed already ending in one is not re-marked, so reopening an untouched
+   * session leaves that event at a smaller seq than `firstLiveSeq`. Prefer
+   * this field in-process: it is exact before the marker reaches storage.
+   *
+   * When this lifecycle appends the marker, it occupies this seq before the
+   * store attaches and therefore does not publish either. Otherwise this seq
+   * holds an ordinary published write.
    */
   readonly firstLiveSeq: number
 
@@ -427,6 +438,13 @@ export class Session {
     }
     this.firstLiveSeq = this.log.length
     this.header = snapshotSessionHeader(id, header)
+    // Appended here so the marker is already in `events` when a backend
+    // captures the creation seed: no load-time write. Re-marking is skipped
+    // because a cold session is resumed on first touch, so repeatedly opening
+    // one must not grow its log per open.
+    if (this.firstLiveSeq > 0 && this.log.at(-1)?.type !== 'session/end-seed') {
+      this.append('session/end-seed', {})
+    }
   }
 
   /** Cached immutable public snapshot of the private append-only log. */

packages/core/session/src/invariant.ts

@@ -144,6 +144,9 @@ function validateEvent(
     }
     case 'user/message':
       break
+    case 'session/end-seed':
+      // Unconstrained: an unbalanced seed legally puts it inside an open turn.
+      break
     case 'steering/message':
     case 'todo/write':
     case 'request/header': {

packages/core/session/src/repair.ts

@@ -1,7 +1,10 @@
 /**
  * Crash-recovery repair for an interrupted session log. It preserves a fully
  * written final turn and supplies the missing tool, step, and turn boundaries
- * needed to resume with a provider-valid transcript.
+ * needed to resume with a provider-valid transcript, plus the activity-time
+ * read that must skip the end-seed boundary — which this module does
+ * not write (`Session`'s constructor does) but whose synthetic closers can
+ * inherit that boundary's timestamp, the one real coupling between the two.
  * @module @deepseek-ai/dsh-session/repair
  */
 
@@ -9,6 +12,22 @@ import { MessageId, freezeMessage, type CallId } from '@deepseek-ai/dsh-llm'
 import type { ToolResultMessage } from '@deepseek-ai/dsh-llm'
 import type { SessionEvent } from './types.ts'
 
+/**
+ * The `time` of the log's last event representing actual work, skipping the
+ * `session/end-seed` boundary — picking a session up is not activity, so
+ * activity ordering must exclude it.
+ *
+ * Excluded by type, so a pickup time still leaks when a boundary is the last
+ * event of an open turn: {@link interruptedTurnClosers} copies it onto the
+ * synthetic `turn/end`, which this counts as work. Reachable only by seeding an
+ * unbalanced log directly — `load()` balances first.
+ * @param events - the log to scan, in seq order.
+ * @returns the latest non-boundary event's `time`, or undefined when there is none.
+ */
+export function lastActivityTime(events: readonly SessionEvent[]): number | undefined {
+  return events.findLast(event => event.type !== 'session/end-seed')?.time
+}
+
 /** Recovery code for an assistant tool request that never reached a recorded call start. */
 export const TOOL_NOT_STARTED = 'TOOL_NOT_STARTED'
 

packages/core/session/src/types.ts

@@ -250,6 +250,29 @@ export interface SessionEventMap {
    * It is log-only; the latest snapshot reconstructs the request header.
    */
   'request/header': { header: EpochHeader; reason: RequestHeaderReason }
+  /**
+   * Marks the end of a constructor seed. Events before it have smaller seq
+   * values and came from the seed (resume, fork, or replay); this lifecycle
+   * produced none of them. This log-only event is the durable projection of
+   * {@link Session.firstLiveSeq}. Its payload is empty — position and `time`
+   * carry the meaning.
+   *
+   * Locate the LAST one in stored history. A seed already ending in one is not
+   * re-marked, so reopening an untouched session does not grow its log per
+   * pickup and the event need not be at the current `firstLiveSeq`.
+   *
+   * `Session`'s constructor is the only legitimate writer. The invariant
+   * companion deliberately constrains nothing here, so a plugin appending one
+   * would silently classify every live bracket before it as seed history.
+   *
+   * An owner of a standalone open/close bracket (`compact/start` …
+   * `compact/end`) reads it because seed history and live work are otherwise
+   * byte-identical: an unmatched opening marker before this event belongs to
+   * an ended lifecycle, whatever ended it. NOT a liveness signal about other
+   * writers — a concurrently live session holds its own boundary elsewhere,
+   * so tolerating concurrent writers needs a signal beyond the log.
+   */
+  'session/end-seed': Record<string, never>
 }
 
 /** The appendable event-type keys of {@link SessionEventMap}, plugin-merged extensions included. */

packages/core/session/tests/fork.spec.ts

@@ -7,6 +7,8 @@ import type { SessionEvent, TurnEndReason } from '@deepseek-ai/dsh-session'
 declare module '@deepseek-ai/dsh-session' {
   interface SessionEventMap {
     'test/log-only': { value: string }
+    /** Stands in for a plugin's open/close bracket (`compact/start`). */
+    'test/bracket-open': { id: string }
   }
 }
 
@@ -50,6 +52,14 @@ function lastSeq(session: Session): number {
   return event.seq
 }
 
+/** A seeded child's constructor seed: its log minus the end-seed marker. */
+function inherited(session: Session): readonly SessionEvent[] {
+  const events = session.events
+  const last = events.at(-1)
+  if (last?.type !== 'session/end-seed') throw new Error('seeded child is missing its end-seed marker')
+  return events.slice(0, -1)
+}
+
 describe('SessionStore.fork', () => {
   it('forks an empty live session as an empty child with lineage metadata', async () => {
     const { ctx, sessions } = await setup()
@@ -73,7 +83,7 @@ describe('SessionStore.fork', () => {
 
     const child = sessions.fork(SessionId('parent'), undefined, SessionId('child'))
 
-    expect(child.events).toEqual(source.events)
+    expect(inherited(child)).toEqual(source.events)
     expect(child.events).not.toBe(source.events)
     expect(child.events[1]).not.toBe(source.events[1])
     expect(() => {
@@ -97,8 +107,8 @@ describe('SessionStore.fork', () => {
 
     const child = sessions.fork(source, undefined, SessionId('log-only-child'))
 
-    expect(child.events).toEqual(source.events)
-    expect(child.events.at(-1)).toMatchObject({
+    expect(inherited(child)).toEqual(source.events)
+    expect(inherited(child).at(-1)).toMatchObject({
       type: 'test/log-only',
       data: { value: 'after execution' },
     })
@@ -114,7 +124,7 @@ describe('SessionStore.fork', () => {
 
     const child = sessions.fork(source, firstBoundary, SessionId('child-from-first'))
 
-    expect(child.events).toEqual(source.events.slice(0, firstBoundary + 1))
+    expect(inherited(child)).toEqual(source.events.slice(0, firstBoundary + 1))
     expect(child.header.seedLength).toBe(firstBoundary + 1)
     expect(child.deriveMessages()).toEqual([{
       id: expect.any(String) as unknown,
@@ -141,11 +151,32 @@ describe('SessionStore.fork', () => {
 
       const child = sessions.fork(source, lastSeq(source), SessionId(`child-${reason.kind}`))
 
-      expect(child.events.at(-1)?.type).toBe('turn/end')
+      expect(inherited(child).at(-1)?.type).toBe('turn/end')
       expect(child.header.seedLength).toBe(source.events.length)
     }
   })
 
+  it('marks a bracket the child inherited from a still-running parent', async () => {
+    // The constructor placement's central claim, unreachable from the
+    // persistence load path.
+    const { ctx, sessions } = await setup()
+    const parent = ctx.sessions.create(SessionId('bracket-parent'), { meta: { cwd: '/workspace' } })
+    appendClosedTurn(parent, 1, 'work')
+    const open = parent.append('test/bracket-open', { id: 'op-1' })
+
+    const child = sessions.fork(parent, undefined, SessionId('bracket-child'))
+
+    // Parent: no end-seed event follows the bracket, so its owner treats it as live.
+    expect(parent.events.at(-1)).toBe(open)
+    expect(parent.events.some(event => event.type === 'session/end-seed')).toBe(false)
+    // Child: the same bracket is before end-seed, so it belongs to the seed.
+    const boundary = child.events.at(-1)
+    expect(boundary).toMatchObject({ type: 'session/end-seed' })
+    expect(boundary!.seq).toBeGreaterThan(open.seq)
+    expect(child.firstLiveSeq).toBe(open.seq + 1)
+    expect(inherited(child).at(-1)).toMatchObject({ type: 'test/bracket-open', data: { id: 'op-1' } })
+  })
+
   it('rejects invalid boundaries before creating a child', async () => {
     const { ctx, sessions } = await setup()
     const empty = ctx.sessions.create(SessionId('empty'))

packages/core/session/tests/invariant.spec.ts

@@ -382,6 +382,24 @@ describe('session-log invariants', () => {
       .toThrow(/turn 1 is still open/)
   })
 
+  it('accepts end-seed whether or not a turn is open', async () => {
+    const { ctx } = await setup()
+    // Balanced seed: between turns.
+    expect(() => ctx.sessions.create(SessionId('inherited-between-turns'), { seed: [
+      { type: 'turn/start', seq: 0, time: 1, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
+      { type: 'turn/end', seq: 1, time: 2, data: { turn: 1, reason: { kind: 'completed' } } },
+    ] })).not.toThrow()
+    // Unbalanced seed: inside the open turn, which the relation permits.
+    const open = ctx.sessions.create(SessionId('inherited-inside-open-turn'), { seed: [
+      { type: 'turn/start', seq: 0, time: 1, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
+    ] })
+    expect(open.events.map(event => event.type)).toEqual(['turn/start', 'session/end-seed'])
+    // Still open afterwards: the boundary moves no cursor.
+    expect(() => open.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } }))
+      .toThrow(/turn 1 is still open/)
+    expect(() => open.append('turn/end', { turn: 1, reason: { kind: 'completed' } })).not.toThrow()
+  })
+
   it('removes all listeners when the companion is disposed', async () => {
     const { ctx, fiber } = await setup()
     const session = ctx.sessions.create()

packages/core/session/tests/properties.spec.ts

@@ -112,7 +112,19 @@ describe('Session properties', () => {
       const original = build(events)
       const replayed = new Session(SessionId(`replay-${counter++}`), [...original.events])
       expect(replayed.deriveMessages()).toEqual(original.deriveMessages())
-      expect(replayed.seq).toBe(original.seq)
+      // A non-empty replay grows by exactly one log-only boundary.
+      expect(replayed.events.slice(0, original.seq)).toEqual(original.events)
+      expect(replayed.seq).toBe(original.seq === 0 ? 0 : original.seq + 1)
+    }))
+  })
+
+  it('replaying a log that already ends in end-seed adds no further marker', () => {
+    fc.assert(fc.property(logArb, (events) => {
+      const original = build(events)
+      const once = new Session(SessionId(`idem-a-${counter++}`), [...original.events])
+      const twice = new Session(SessionId(`idem-b-${counter++}`), [...once.events])
+      // Lazy resume makes browsing a pickup, so this must not grow per open.
+      expect(twice.events).toEqual(once.events)
     }))
   })
 

packages/core/session/tests/repair.spec.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import { CallId , createMessage, createToolResultMessage } from '@deepseek-ai/dsh-llm'
-import { interruptedTurnClosers, TOOL_NOT_STARTED, TOOL_OUTCOME_UNKNOWN } from '../src/index.ts'
+import { interruptedTurnClosers, lastActivityTime, TOOL_NOT_STARTED, TOOL_OUTCOME_UNKNOWN } from '../src/index.ts'
 import type { SessionEvent, SurfaceEvent } from '../src/index.ts'
 
 /**
@@ -273,3 +273,44 @@ describe('interruptedTurnClosers', () => {
     expect(closers.map(e => e.type)).toEqual(['step/end', 'turn/end'])
   })
 })
+
+describe('lastActivityTime', () => {
+  const endSeedAt = (seq: number, time: number): SessionEvent =>
+    ({ type: 'session/end-seed', seq, time, data: {} })
+
+  it('has no answer for an empty log', () => {
+    expect(lastActivityTime([])).toBeUndefined()
+  })
+
+  it('reports the log tail when no boundary is present', () => {
+    const events: SessionEvent[] = [
+      userTurnStart(1, 0),
+      { type: 'turn/end', seq: 1, time: 500, data: { turn: 1, reason: { kind: 'completed' } } },
+    ]
+    expect(lastActivityTime(events)).toBe(500)
+  })
+
+  it('skips a trailing boundary in favour of the last real work', () => {
+    const events: SessionEvent[] = [
+      userTurnStart(1, 0),
+      { type: 'turn/end', seq: 1, time: 500, data: { turn: 1, reason: { kind: 'completed' } } },
+      endSeedAt(2, 9_000),
+    ]
+    // Resumed long after the work, but never worked in again.
+    expect(lastActivityTime(events)).toBe(500)
+  })
+
+  it('reports work appended after end-seed', () => {
+    const events: SessionEvent[] = [
+      userTurnStart(1, 0),
+      endSeedAt(1, 9_000),
+      { type: 'turn/end', seq: 2, time: 9_500, data: { turn: 1, reason: { kind: 'completed' } } },
+    ]
+    expect(lastActivityTime(events)).toBe(9_500)
+  })
+
+  it('has no answer for a log of nothing but boundaries', () => {
+    // Unreachable via the constructor, but the projection is a pure function.
+    expect(lastActivityTime([endSeedAt(0, 1), endSeedAt(1, 2)])).toBeUndefined()
+  })
+})

packages/core/session/tests/session.spec.ts

@@ -112,7 +112,7 @@ describe('Session', () => {
     session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
     session.append('turn/end', { turn: 1, reason: { kind: 'aborted' } })
     const replayed = new Session(SessionId('aborted-replay'), structuredClone(session.events))
-    expect(replayed.events).toEqual(session.events)
+    expect(replayed.events.slice(0, -1)).toEqual(session.events)
     const turnEnd = replayed.events.findLast(event => event.type === 'turn/end')
     expect(turnEnd?.type === 'turn/end' && turnEnd.data.reason).toEqual({ kind: 'aborted' })
   })
@@ -188,7 +188,10 @@ describe('Session', () => {
 
     const replayed = new Session(SessionId('s3-replay'), [...original.events])
     expect(replayed.deriveMessages()).toEqual(original.deriveMessages())
-    expect(replayed.seq).toBe(original.seq)
+    // The seed verbatim, plus the end-seed event the constructor appends.
+    expect(replayed.events.slice(0, original.seq)).toEqual(original.events)
+    expect(replayed.seq).toBe(original.seq + 1)
+    expect(replayed.firstLiveSeq).toBe(original.seq)
   })
 
   it('rejects pre-provider request headers and assistant messages on seed/load', () => {
@@ -217,7 +220,7 @@ describe('Session', () => {
     const unrelatedPrimitiveData = {
       type: 'plugin/event', seq: 0, time: 1, data: null,
     } as unknown as SessionEvent
-    expect(new Session(SessionId('primitive-plugin-data'), [unrelatedPrimitiveData]).events)
+    expect(new Session(SessionId('primitive-plugin-data'), [unrelatedPrimitiveData]).events.slice(0, 1))
       .toEqual([unrelatedPrimitiveData])
   })
 
@@ -522,7 +525,8 @@ describe('Session', () => {
       { type: 'turn/end' as const, seq: 2, time: 3, data: { turn: 1, reason: { kind: 'completed' as const } } },
     ] as SessionEvent[]
     const session = new Session(SessionId('seed-ok'), goodSeed)
-    expect(session.events).toHaveLength(3)
+    expect(session.events.slice(0, 3)).toEqual(goodSeed)
+    expect(session.firstLiveSeq).toBe(3)
   })
 
   it('reads each seed array entry once so validation and storage use the same event', () => {
@@ -546,7 +550,7 @@ describe('Session', () => {
     const session = new Session(SessionId('seed-entry-snapshot'), seed)
 
     expect(reads).toBe(1)
-    expect(session.events).toEqual([accepted])
+    expect(session.events.slice(0, 1)).toEqual([accepted])
   })
 
   it('reads a nested seed-data getter once and stores its first JSON value', () => {
@@ -624,7 +628,7 @@ describe('Session', () => {
 
     const session = new Session(SessionId('seed-null-prototype'), [event])
 
-    expect(session.events).toEqual([{ ...event }])
+    expect(session.events.slice(0, 1)).toEqual([{ ...event }])
   })
 
   it('reads a nested seed-metadata getter once and stores its first JSON value', () => {
@@ -1647,6 +1651,7 @@ describe('todo/write event', () => {
     const replayed = new Session(SessionId('t4-replay'), [...original.events])
     expect(replayed.events.findLast(e => e.type === 'todo/write')!.data.todos)
       .toEqual([{ content: 'only', status: 'completed' }])
-    expect(replayed.seq).toBe(original.seq)
+    expect(replayed.events.slice(0, original.seq)).toEqual(original.events)
+    expect(replayed.firstLiveSeq).toBe(original.seq)
   })
 })

packages/host/apiproxy/README.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 packages/host/apiproxy/README.md
-README.md: 8efb47acca08e6179aa2fbfbe705550c7ed45561
-README.zh.md: 69ccc5c36334e5f5b573ea9fd1608df56714e67a
+README.md: d839563319350ed91eee769fb05b6a9ee2391265
+README.zh.md: 3a3021f1770f2629e8667aa33886712c5d5d002b

packages/host/apiproxy/README.md

@@ -46,3 +46,4 @@ None; this package neither assembles nor sends a provider request.
 - **Reserved seams stay out of `RpcMethodMap`** — `session.fork`, `prompt.mode: 'inject'`, `task.list`, `host.listModels`, and a describe `hostInstanceId` are documented reservations; an unknown method fails loud at envelope parse rather than getting a not-implemented code.
 - **No protocol version field** — client and host ship together; `host.describe` gains a version negotiation field only when an independently released client exists.
 - **Linux native picker requires desktop tooling** — under the `native` capability, `host.pickDirectory` reports an actionable error when neither Zenity nor KDialog is installed; the browse backend is the composition-level fallback (see the [native backend README](../directory-picker-native/README.md)).
+- **A cold session's `updatedAt` counts a mere pickup as a write (per-file backends only)** — the attached projection excludes the `session/end-seed` boundary, because picking a session up is not activity, but a cold session's `updatedAt` is its log file's mtime and every durable write refreshes that, the boundary included. `agentFor()` resumes a cold session on first touch, so merely opening one in a client writes it. This applies only where `locate()` resolves a per-session artifact, i.e. JSONL; SQLite returns `undefined`, so its cold sessions fall back to `createdAt` and are skewed the other way — too old rather than too new — independently of this boundary. A session touched without being worked in therefore sorts newer than its last real activity until it attaches. Separating the two needs a log read, which is exactly what the mtime path exists to avoid; a stored last-activity field in the index would fix it at the source, scoped in the [last-activity-index Agent Note](../../../.agents/notes/proposed/architecture/2026-07-29-durable-last-activity-index.md).

packages/host/apiproxy/README.zh.md

@@ -46,3 +46,4 @@ Workspace 列表与 Session 列表是相互独立的重连基线。`workspace.cr
 - **预留 seam 不进入 `RpcMethodMap`**：`session.fork`、`prompt.mode: 'inject'`、`task.list`、`host.listModels` 和描述字段 `hostInstanceId` 都是已记录的预留项；未知方法会在信封解析时直接失败，而不会返回「尚未实现」错误码。
 - **没有协议版本字段**：客户端与宿主一同发布；只有出现独立发布的客户端后，`host.describe` 才会增加版本协商字段。
 - **Linux 原生选择器依赖桌面工具**：在 `native` 能力下，Zenity 和 KDialog 均未安装时，`host.pickDirectory` 会给出包含解决建议的错误提示；组合层面的回退是 browse 后端（见 [native 后端 README](../directory-picker-native/README.md)）。
+- **冷会话的 `updatedAt` 会把一次单纯的拾起算作写入（仅逐文件后端）**：已附加投影排除了 `session/end-seed` 边界，因为接手一个会话不算活动；但冷会话的 `updatedAt` 取自其日志文件的 mtime，而每一次持久写入都会刷新它，包括这条边界。`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会写入它。这只适用于 `locate()` 能解析出逐会话产物的场景，即 JSONL；SQLite 返回 `undefined`，因此它的冷会话回退到 `createdAt`，偏差方向相反——偏旧而不是偏新——且与这条边界无关。于是一个被触碰过却没有在里面工作过的会话，在重新附加之前会排在它最后一次真实活动之后。要把两者区分开需要读取日志，而这恰恰是 mtime 路径存在的目的；在索引中存储一个最后活动字段可以从源头修好它，范围见[最后活动索引 Agent Note](../../../.agents/notes/proposed/architecture/2026-07-29-durable-last-activity-index.md)。

packages/host/apiproxy/src/api-proxy.ts

@@ -14,7 +14,7 @@ import type {
 import { createUserMessage, ReasoningEffortId } from '@deepseek-ai/dsh-llm'
 import { errorChain } from '@deepseek-ai/dsh-llm'
 import type { MessageSource } from '@deepseek-ai/dsh-llm'
-import { isAppendSurfaceEvent } from '@deepseek-ai/dsh-session'
+import { isAppendSurfaceEvent, lastActivityTime } from '@deepseek-ai/dsh-session'
 import type { Session, SessionEvent, SessionHeader, SessionId, UserMessage } from '@deepseek-ai/dsh-session'
 import type { SessionPersistence } from '@deepseek-ai/dsh-session-persistence'
 import type { Workspace, WorkspaceRecord } from '@deepseek-ai/dsh-workspace'
@@ -169,7 +169,9 @@ function sessionBlank(session: Session): boolean {
 function summarize(session: Session, running: boolean): SessionSummary {
   return {
     sessionId: session.id,
-    updatedAt: session.events.at(-1)?.time ?? session.header.createdAt,
+    // Excludes end-seed: a resumed-but-untouched session
+    // must not sort as freshly worked in.
+    updatedAt: lastActivityTime(session.events) ?? session.header.createdAt,
     running,
     blank: sessionBlank(session),
     ...session.header.parentSession === undefined ? {} : { parentSessionId: session.header.parentSession },

packages/host/apiproxy/src/api/sessions.ts

@@ -133,7 +133,11 @@ export type QueueAction =
 /** Session list entry (v1 builds no index: list does readdir+stat). */
 export interface SessionSummary {
   sessionId: SessionId
-  /** Persisted file mtime. */
+  /**
+   * Last activity. Attached: the last non-`session/end-seed` event, since a
+   * pickup is not activity. Cold: the log's mtime, or `createdAt` for a backend
+   * with no per-session file (README Known Limitations covers the skew).
+   */
   updatedAt: number
   /** Status of the attached agent; always false for cold (unattached) sessions. */
   running: boolean

packages/host/apiproxy/tests/api-proxy-cold.spec.ts

@@ -78,6 +78,42 @@ describe('sessions.list cold merge', () => {
   })
 })
 
+describe('attached updatedAt excludes end-seed', () => {
+  it('reports the last real work, not the pickup, so a resumed-untouched session does not float', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(UserInteractionService)
+    await ctx.plugin(AgentRegistry)
+    const api = createApiProxy(ctx, { provider: 'p', model: 'm', cwd: '/tmp', workspaceRoot: '/tmp' })
+
+    // Old work, resumed just now: the log tail would report the pickup.
+    const worked = 1_000_000
+    const resumed = ctx.sessions.create(sid('resumed-untouched'), {
+      seed: [
+        { type: 'turn/start', seq: 0, time: worked, data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } } },
+        { type: 'turn/end', seq: 1, time: worked, data: { turn: 1, reason: { kind: 'completed' } } },
+      ],
+      meta: { cwd: '/proj', createdAt: 500 },
+    })
+    ctx.agents.register({ id: resumed.id, session: resumed, status: 'idle', ctx } as Agent)
+    const boundary = resumed.events.at(-1)
+    expect(boundary?.type).toBe('session/end-seed')
+    expect(boundary?.time).toBeGreaterThan(worked)
+
+    const listed = await api.sessions.list(request({}))
+    if (!listed.result.ok) throw new Error('list failed')
+    const summary = listed.result.value.items.find(item => item.sessionId === 'resumed-untouched')
+    expect(summary?.updatedAt).toBe(worked)
+
+    // Real work appended after end-seed does move it.
+    resumed.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } })
+    const after = await api.sessions.list(request({}))
+    if (!after.result.ok) throw new Error('list failed')
+    const moved = after.result.value.items.find(item => item.sessionId === 'resumed-untouched')
+    expect(moved?.updatedAt).toBeGreaterThan(worked)
+  })
+})
+
 describe('degenerate composition (no persistence, no factory)', () => {
   it('list skips the cold merge and resume maps a non-not-found failure to internal', async () => {
     const ctx = new Context()

packages/llm/token-meter/tests/token-meter.spec.ts

@@ -417,7 +417,8 @@ describe('replay anchors and surface folds', () => {
     expect(after.surfaceDeltaTokens).toBeLessThan(0)
     expectSurfaceTotal(after)
     expect(before.nodes).toHaveLength(2)
-    expect(before.logRevision).toBe(original.events.length)
+    // The earlier snapshot still reports the log it measured: seed + boundary.
+    expect(before.logRevision).toBe(original.events.length + 1)
     expect(before.surfaceDeltaTokens).toBeGreaterThan(0)
   })
 
@@ -677,13 +678,15 @@ describe('malformed replay and listener lifecycle', () => {
       content: [{ type: 'text', text: 'one' }],
       source: { kind: 'user' },
     }), { surfaceOp: 'append' })
-    expect(revisions).toEqual([2])
-    expect(activeMeter.measure(session).logRevision).toBe(2)
+    // Seed, end-seed, then one live append. Only the last event published:
+    // end-seed predates store attachment, like the seed.
+    expect(revisions).toEqual([3])
+    expect(activeMeter.measure(session).logRevision).toBe(3)
 
     await firstFiber.dispose()
     const secondFiber = await ctx.plugin(TokenMeterService)
     activeMeter = ctx.tokenMeter
-    expect(activeMeter.measure(session).logRevision).toBe(2)
+    expect(activeMeter.measure(session).logRevision).toBe(3)
     await secondFiber.dispose()
   })
 })

packages/session-persistence/session-persistence-jsonl/tests/jsonl.spec.ts

@@ -378,7 +378,9 @@ describe('SessionPersistenceJsonl: durability and crash semantics', () => {
     await ctx.sessions.flush(child)
     const loaded = await ctx.sessionPersistence.load(child.id)
 
-    expect(loaded.events).toEqual(source.events)
+    // The constructor seed reaches disk verbatim, then the child's end-seed.
+    expect(loaded.events.slice(0, source.events.length)).toEqual(source.events)
+    expect(loaded.events.at(-1)).toMatchObject({ type: 'session/end-seed', seq: source.events.length })
     expect(loaded.meta).toMatchObject({
       id: SessionId('persist-child'),
       cwd: '/workspace',

packages/session-persistence/session-persistence/tests/coordinator-contract.ts

@@ -218,7 +218,9 @@ export function runCoordinatorContract(name: string, makeFixture: () => Promise<
         live.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
         await ctx.sessions.flush(live)
         const loaded = await ctx.sessionPersistence.load(id)
-        expect(loaded.events.map(event => event.type)).toEqual(['turn/start', 'turn/end'])
+        // The constructor's end-seed event persisted between the stored
+        // turn/start and the turn/end appended live.
+        expect(loaded.events.map(event => event.type)).toEqual(['turn/start', 'session/end-seed', 'turn/end'])
         expect(loaded.events.at(-1)).toMatchObject({
           type: 'turn/end',
           data: { reason: { kind: 'completed' } },
@@ -477,11 +479,14 @@ export function runCoordinatorContract(name: string, makeFixture: () => Promise<
         const forked = ctx.sessions.create(SessionId('forked'), { seed, meta: { cwd: WORK } })
         await ctx.sessions.flush(forked) // onCreated persisted the seed
         const loaded = await ctx.sessionPersistence.load(SessionId('forked'))
-        expect(loaded.events).toEqual(seed)
+        // Fork is where the marker earns its keep: the inherited prefix may
+        // carry a bracket the still-running parent owns.
+        expect(loaded.events.slice(0, seed.length)).toEqual(seed)
+        expect(loaded.events.at(-1)).toMatchObject({ type: 'session/end-seed', seq: seed.length })
         // A flush with no NEW events must not double-write.
         await ctx.sessions.flush(forked)
         const reloaded = await ctx.sessionPersistence.load(SessionId('forked'))
-        expect(reloaded.events).toEqual(seed)
+        expect(reloaded.events).toEqual(loaded.events)
       } finally {
         await fiber.dispose()
         await fix.cleanup()
@@ -510,7 +515,9 @@ export function runCoordinatorContract(name: string, makeFixture: () => Promise<
         await second.ctx.sessions.flush(s2)
 
         const reloaded = await second.ctx.sessionPersistence.load(SessionId('resumed'))
-        expect(reloaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5, 6, 7])
+        // 0-5 the resumed seed, 6 end-seed, 7-8 the new turn.
+        expect(reloaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5, 6, 7, 8])
+        expect(reloaded.events[6]).toMatchObject({ type: 'session/end-seed' })
       } finally {
         await second.fiber.dispose()
         await fix.cleanup()
@@ -791,7 +798,9 @@ export function runCoordinatorContract(name: string, makeFixture: () => Promise<
         const live = ctx.sessions.create(SessionId('lazy-claim'), { seed: oneTurnLog(), meta: { cwd: WORK } })
         await expect(ctx.sessions.flush(live)).resolves.toBeUndefined()
         const loaded = await ctx.sessionPersistence.load(SessionId('lazy-claim'))
-        expect(loaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5])
+        // Seeded 0-5 plus the constructor's end-seed event at 6.
+        expect(loaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5, 6])
+        expect(loaded.events.at(-1)).toMatchObject({ type: 'session/end-seed' })
       } finally {
         await fiber.dispose()
         await fix.cleanup()
@@ -844,7 +853,9 @@ export function runCoordinatorContract(name: string, makeFixture: () => Promise<
         }, { inject: ['sessions'] }))
         await ctx.sessions.flush(cont)
         const loaded = await ctx.sessionPersistence.load(SessionId('claim'))
-        expect(loaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5, 6, 7])
+        // 6-7 the claimed suffix; 8 end-seed after the whole seed.
+        expect(loaded.events.map(e => e.seq)).toEqual([0, 1, 2, 3, 4, 5, 6, 7, 8])
+        expect(loaded.events.at(-1)).toMatchObject({ type: 'session/end-seed' })
         expect(loaded.meta).toEqual(durableMeta)
         expect(loaded.meta.createdAt).toBe(1000)
 

packages/session-query/session-query-sqlite/tests/sqlite.spec.ts

@@ -1077,8 +1077,9 @@ describe('SQLite reconciliation and source lifecycle', () => {
     await expect(ctx.sessionQuery.searchEvents({ sessionId: live.id, query: 'needle' }))
       .rejects.toThrow(expectCode('SESSION_QUERY_INDEX_FAILED'))
     db.exec('PRAGMA query_only = OFF')
+    // seq 2: one-event seed, end-seed, then the live message.
     await expect(ctx.sessionQuery.searchEvents({ sessionId: live.id, query: 'needle' }))
-      .resolves.toMatchObject({ items: [{ seq: 1 }] })
+      .resolves.toMatchObject({ items: [{ seq: 2 }] })
   })
 })
 

packages/session-title/session-title/tests/service-contracts.spec.ts

@@ -185,6 +185,8 @@ describe('SessionTitleService configuration and refresh boundaries', () => {
       'turn/start',
       'user/message',
       'turn/end',
+      // The seeded constructor's end-seed marker.
+      'session/end-seed',
       'session/title',
     ])
     expect(ctx.sessionTitle.get(session)?.messageSeqs).toEqual([source.seq])

packages/subagent/subagent-inprocess/tests/inheritance.spec.ts

@@ -126,9 +126,10 @@ describe('in-process policy inheritance', () => {
 
       expect(child.session.header.seedLength).toBe(1)
       expect(child.session.firstLiveSeq).toBe(seed.length)
+      // seq 1 is the constructor's end-seed marker.
       expect(child.session.events.filter(event => event.type === 'sandbox/mode')).toMatchObject([
         { seq: 0, data: { mode: 'workspace-write' } },
-        { seq: 1, data: { mode: 'read-only', source: 'delegation' } },
+        { seq: 2, data: { mode: 'read-only', source: 'delegation' } },
       ])
       await expect(readFile(blocked, 'utf8')).rejects.toMatchObject({ code: 'ENOENT' })
       expect(ctx.sandboxPolicy.overrideOf(child.session)).toBe('read-only')

packages/telemetry/session-telemetry/tests/telemetry.spec.ts

@@ -186,10 +186,12 @@ describe('TelemetryCoordinator adoption', () => {
 
     const seqs = backend.ledger().map(r => [r.attributes['session.id'], r.attributes['event.seq']])
     expect(seqs).toEqual(expect.arrayContaining([['seed-parent', 0], ['seed-parent', 1]]))
-    expect(seqs.filter(([id]) => id === 'seeded')).toEqual([['seeded', 2]])
+    // 2 end-seed, 3 turn/end: both this lifecycle's own writes, while
+    // inherited 0-1 stay with the parent stream.
+    expect(seqs.filter(([id]) => id === 'seeded')).toEqual([['seeded', 2], ['seeded', 3]])
   })
 
-  it('resume shape: a full-log seed exports nothing yet still rebuilds the chunk projection', async () => {
+  it('resume shape: a full-log seed exports only its own end-seed and rebuilds the chunk projection', async () => {
     const backend = new FakeBackend()
     const ctx = new Context()
     await ctx.plugin(SessionStore)
@@ -205,14 +207,16 @@ describe('TelemetryCoordinator adoption', () => {
     const ofResumed = () => backend.ledger()
       .filter(r => r.attributes['session.id'] === 'resumed')
       .map(r => r.attributes['event.seq'])
-    expect(ofResumed()).toEqual([])
+    // Nothing inherited is re-exported; seq 2 is this session's own first
+    // write — the end-seed event its constructor appended after the seed.
+    expect(ofResumed()).toEqual([2])
     // The seed fed the projection: the (turn 1, step 1) first chunk already
     // shipped from the original process, so its continuation is re-dropped…
     resumed.append('assistant/chunk', { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'continuation' } })
-    expect(ofResumed()).toEqual([])
+    expect(ofResumed()).toEqual([2])
     // …while a new step's first chunk exports normally.
     resumed.append('assistant/chunk', { turn: 1, step: 2, chunk: { type: 'text-delta', index: 0, text: 'next step' } })
-    expect(ofResumed()).toEqual([3])
+    expect(ofResumed()).toEqual([2, 4])
   })
 
   it('stamps session.seed_length from the header so receivers can stitch fork streams', async () => {

packages/ui/tui/src/components/dialogs.ts

@@ -23,6 +23,7 @@ import {
   type AgentLlmTarget,
 } from '@deepseek-ai/dsh-agent'
 import type { LlmModelInfo, LlmModelReasoningInfo, ReasoningEffortId } from '@deepseek-ai/dsh-llm'
+import { lastActivityTime } from '@deepseek-ai/dsh-session'
 import type { SessionId } from '@deepseek-ai/dsh-session'
 import { foldGoal, type GoalPhase } from '@deepseek-ai/dsh-goal'
 import { foldSessionTitle } from '@deepseek-ai/dsh-session-title'
@@ -512,7 +513,8 @@ export function summarizeResumeCandidate(
   return {
     record,
     title,
-    lastActivityAt: snapshot.events.at(-1)?.time ?? snapshot.session.createdAt,
+    // Excludes a prior pickup's boundary, or every browsed session floats up.
+    lastActivityAt: lastActivityTime(snapshot.events) ?? snapshot.session.createdAt,
     lastTurn: resumeTurnLabel(snapshot),
     currentWorkspace: record.header.cwd === cwd,
     workspaceLabel: formatWorkspace(record.header.cwd),

packages/ui/tui/src/index.ts

@@ -36,6 +36,7 @@ import type {} from '@deepseek-ai/dsh-llm-retry'
 import { renderPrompt } from '@deepseek-ai/dsh-system-prompt'
 import {
   isReplacementSurfaceEvent,
+  lastActivityTime,
   SessionId,
   type SessionEvent,
   type UserMessage,
@@ -1008,7 +1009,7 @@ export function createTuiChat(
     const systemPrompt = displayText(renderPrompt(assembly)) || '(empty)'
     const registeredTools = assembly.tools.map(tool => displayText(tool.name)).join(', ') || '(none)'
     const events = agent.session.events
-    const latestActivity = events.at(-1)?.time ?? agent.session.header.createdAt
+    const latestActivity = lastActivityTime(events) ?? agent.session.header.createdAt
     const usedContext = Math.max(0, Math.round(ctx.tokenMeter.measure(agent.session).totalTokens))
     let context = `${formatDiagnosticNumber(usedContext)} used · capacity unknown`
     const contextWindow = modelController.contextWindow()

packages/ui/tui/tests/snapshots/status-diagnostics-narrow.expected.txt

@@ -48,7 +48,7 @@ buffer
 17| "│                                                      │"
   style 0-0 dim
   style 55-55 dim
-18| "│  Agent:      idle · 7 events · 1 turn · 1 step · 1   │"
+18| "│  Agent:      idle · 8 events · 1 turn · 1 step · 1   │"
   style 0-0 dim
   style 3-12 dim
   style 55-55 dim

packages/ui/tui/tests/snapshots/status-diagnostics.expected.txt

@@ -45,7 +45,7 @@ buffer
 16| "│                                                                                │"
   style 0-0 dim
   style 81-81 dim
-17| "│  Agent:      idle · 7 events · 1 turn · 1 step · 1 tool call                   │"
+17| "│  Agent:      idle · 8 events · 1 turn · 1 step · 1 tool call                   │"
   style 0-0 dim
   style 3-12 dim
   style 81-81 dim

packages/ui/tui/tests/tui.snapshot.ts

@@ -878,6 +878,9 @@ describe('TUI terminal-state snapshots', () => {
         { type: 'step/end', seq: 5, time: Date.parse(`${day}T00:00:06Z`), data: { turn: 1, step: 1 } },
         { type: 'turn/end', seq: 6, time: Date.parse(`${day}T00:00:07Z`), data: { turn: 1, reason: { kind: 'completed' } } },
         { type: 'session/title', seq: 7, time: Date.parse(`${day}T00:00:08Z`), data: { title, messageSeqs: [1], source: { kind: 'fallback' } } },
+        // A prior pickup, dated well after the work: the picker must still
+        // show the work's date, not the pickup's.
+        { type: 'session/end-seed', seq: 8, time: Date.parse('2026-07-23T07:59:00.000Z'), data: {} },
       ],
     })
     const harness = await setupSnapshot({
@@ -947,6 +950,12 @@ describe('TUI terminal-state snapshots', () => {
           messageSeqs: [1],
           source: { kind: 'fallback' },
         })
+        // Renders over a boundary-bearing log. It cannot pin the exclusion:
+        // `/status` appends its own `command/run` first, so the boundary is
+        // never the tail here. The other two call sites pin it.
+        dateNow.mockReturnValue(Date.parse('2026-07-22T10:10:11.000Z'))
+        session.append('session/end-seed', {})
+        dateNow.mockReturnValue(Date.parse('2026-07-22T09:10:11.000Z'))
       },
     }, { columns: 92, rows: 32 })
     await renderAfter(harness, () => {