fix(session-projection): advance the view dedup baseline on every change

The change feed stamped lastView only when a listener was subscribed, so a
value change during a listener-free window (HMR swap) froze the baseline
and a later transition back to the old value was silently deduplicated.
The baseline now advances on every changed state, heard or not; broadcast
still only happens with listeners. Docs, catalog, and the feature note
follow the corrected semantics.

.agents/notes/implemented/feature/2026-08-30-web-turn-rail-outline-jump.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-08-30-web-turn-rail-outline-jump.md
-2026-08-30-web-turn-rail-outline-jump.md: 7fa2ba4ee2a09a78b277b238d215413e60dc9a54
-2026-08-30-web-turn-rail-outline-jump.zh.md: 544c43715217e1beda925eb6919cfbd3d5df3907
+2026-08-30-web-turn-rail-outline-jump.md: b2803aebf54c342c08da92131db7617b28ad1620
+2026-08-30-web-turn-rail-outline-jump.zh.md: 547e708a76e2205f7e2a1c83c9b3330975136393

.agents/notes/implemented/feature/2026-08-30-web-turn-rail-outline-jump.md

@@ -14,7 +14,7 @@ Three cooperating pieces, each useful alone.
 
 **Data: the `turnOutline` session projection.** `packages/session/session-turn-outline` registers one pure fold on `ctx.sessionProjections`: every `turn/start` appends an entry (skipping boundaries that do not advance the turn number, keeping the outline strictly increasing), the turn's first human `user/message` fills the prompt preview, and the newest text-bearing `assistant/message` buffers a response draft that `turn/end` commits (`turn/end` itself carries no text). Preview budgets mirror the rail card's clamps — one prompt line at 50 characters, up to three response lines at 120, an ellipsis marking a clip — and match the loaded-turn previews so a turn shows the same words before and after its events load. The wire value is the bare entry array so draft-only state changes keep its identity, and the feed's identity gate (below) then holds pushes to three per turn: boundary, prompt, settled response. The value rides the existing projection carriers — tail-page seed, `session/projection` control frames, projcache — and the web-app bundle mounts the plugin. `seq` is the `turn/start` event seq: the loop logs it before the turn's prompt and steps, so paging a window back through that seq loads the whole turn.
 
-**Change-feed identity gate (session-projection).** The registry's change feed previously fired on every changed state reference of a client-visible unit; it now also compares the raw `view` output against the last delivered one and stays quiet when `Object.is`-identical. This is what lets a unit buffer working fields (the response draft) in state behind an identity-stable projection instead of pushing its whole value per streamed assistant message; units whose views build fresh objects per call are unaffected. The alternative — value-equality dedup in the carrier by serialized comparison — was rejected as it pays a full serialization per quiet change.
+**Change-feed identity gate (session-projection).** The registry's change feed previously fired on every changed state reference of a client-visible unit; it now also compares the raw `view` output against the unit's previous projection and stays quiet when `Object.is`-identical; the baseline advances on every change, heard or not, so a later listener generation still sees every value transition. This is what lets a unit buffer working fields (the response draft) in state behind an identity-stable projection instead of pushing its whole value per streamed assistant message; units whose views build fresh objects per call are unaffected. The alternative — value-equality dedup in the carrier by serialized comparison — was rejected as it pays a full serialization per quiet change.
 
 **Paging: `Session.loadThrough(seq)`.** The session-controller client gains a jump loader beside `loadOlder()`: it loops the existing prepend pager in 200-message pages (`JUMP_PAGE_MESSAGES`) until `baseSeq <= seq`, lowers a shared low-water target when called again mid-jump, stops on a page that leaves `baseSeq` unmoved (the no-progress guard against an empty page still claiming history), and reports busy through the existing `loadingOlder` snapshot bit. No wire change: seqs are dense, so the client computes everything from `beforeSeq` arithmetic.
 

.agents/notes/implemented/feature/2026-08-30-web-turn-rail-outline-jump.zh.md

@@ -14,7 +14,7 @@ Web 聊天的轮次导航栏从已加载的事件窗口推导刻度，而窗口
 
 **数据：`turnOutline` 会话投影。** `packages/session/session-turn-outline` 在 `ctx.sessionProjections` 上注册一个纯 fold：每个 `turn/start` 追加一个条目（跳过未推进轮次号的边界，保持大纲严格递增），该轮首条人类 `user/message` 填入提示词预览，最新一条带文本的 `assistant/message` 缓冲为回复草稿、由 `turn/end` 提交（`turn/end` 自身不带文本）。预览预算对齐导航卡片的截断——提示词一行 50 字符、回复至多三行 120 字符、被裁剪时补省略号——并与已加载轮次的预览一致，同一轮在事件载入前后显示相同的文字。wire 值是裸条目数组，纯草稿的状态变化因此保持其身份，配合下述变更流身份门把推送压到每轮三次：开轮、提示词、落定回复。值搭现有投影载体——尾页 seed、`session/projection` 控制帧、projcache——web-app bundle 挂载该插件。`seq` 是 `turn/start` 事件的 seq：loop 先记它再记该轮的提示词与步骤，窗口向后分页越过该 seq 即载入整轮。
 
-**变更流身份门（session-projection）。** 注册表的变更流此前对客户端可见单元的每次状态引用变化都触发；现在还会把原始 `view` 输出与上一次交付的值比较，`Object.is` 相同即保持安静。正是它让单元可以把工作字段（回复草稿）缓冲在身份稳定投影之后的状态里，而不是每条流式助手消息都推送整值；view 每次新建对象的单元不受影响。备选——在载体侧按序列化比较去重——被否决，因为每次安静变化都要付一次完整序列化。
+**变更流身份门（session-projection）。** 注册表的变更流此前对客户端可见单元的每次状态引用变化都触发；现在还会把原始 `view` 输出与该单元上一次投影值比较，`Object.is` 相同即保持安静；基线随每次变更前进、有无监听者都一样，后来的监听器换代仍能看到每次值转变。正是它让单元可以把工作字段（回复草稿）缓冲在身份稳定投影之后的状态里，而不是每条流式助手消息都推送整值；view 每次新建对象的单元不受影响。备选——在载体侧按序列化比较去重——被否决，因为每次安静变化都要付一次完整序列化。
 
 **分页：`Session.loadThrough(seq)`。** session-controller 客户端在 `loadOlder()` 旁新增跳转加载器：按 200 条 message 一页（`JUMP_PAGE_MESSAGES`）循环现有 prepend 分页器直到 `baseSeq <= seq`，跳转中再次调用会下调共享低水位目标，遇到 `baseSeq` 未动的页即停（对空页仍声称有历史的无进展守卫），忙碌状态复用现有 `loadingOlder` 快照位。零 wire 改动：seq 稠密，客户端仅凭 `beforeSeq` 算术即可。
 

docs/subsystems/session-projection.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/subsystems/session-projection.md
-session-projection.md: ee6b301bde49986fb24e75a8de7fec7b7fc41688
-session-projection.zh.md: 36b6c874b440165ec56dddc938aff030fcc69b49
+session-projection.md: b7709b8d6254166afff08688c463161998731864
+session-projection.zh.md: 71da679e0cf50e6527889fd209a43291371ce313

docs/subsystems/session-projection.md

@@ -86,9 +86,9 @@ interface ProjectionSnapshot {
  * Change-feed listener: one unit's served value changed for one session.
  * `value` is the schema-validated `view` output; `seq` is the unit's
  * watermark at emission (the seq of the event that caused the change). A
- * changed state whose raw `view` output is `Object.is`-identical to the last
- * delivered one does not fire, so a unit can buffer working fields in state
- * behind an identity-stable projection.
+ * changed state whose raw `view` output is `Object.is`-identical to the
+ * unit's previous projection does not fire, so a unit can buffer working
+ * fields in state behind an identity-stable projection.
  */
 type ProjectionChangeListener = (
   session: Session,
@@ -98,7 +98,7 @@ type ProjectionChangeListener = (
 ) => void
 ```
 
-`snapshot(session)` is fully synchronous: a carrier reads it in the same tick as its page slice, so `asOfSeq` covers both reads at one sequence number. It returns only client views, and every value passes its unit's `viewSchema` before return. `stateOf(session, key)` reads one live host state without computing unrelated views; callers must not mutate the borrowed reference. The change feed fires once per client-visible unit whose state *reference* changed for each committed event — unless the raw `view` output is `Object.is`-identical to the last value the feed delivered, so a unit can buffer working fields in state behind an identity-stable projection; `apply` must return the same reference when its state did not change.
+`snapshot(session)` is fully synchronous: a carrier reads it in the same tick as its page slice, so `asOfSeq` covers both reads at one sequence number. It returns only client views, and every value passes its unit's `viewSchema` before return. `stateOf(session, key)` reads one live host state without computing unrelated views; callers must not mutate the borrowed reference. The change feed fires once per client-visible unit whose state *reference* changed for each committed event — unless the raw `view` output is `Object.is`-identical to the unit's previous projection (the baseline advances with every change, heard or not), so a unit can buffer working fields in state behind an identity-stable projection and a later listener generation still sees every value transition; `apply` must return the same reference when its state did not change.
 
 ## The registry: `ctx.sessionProjections`
 
@@ -180,7 +180,7 @@ Source: [`packages/session/session-projection-cache/src/index.ts`](../../package
 
 ### `ctx.sessionProjections` — `SessionProjectionRegistry`
 
-`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit's `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the last delivered one (identity-stable projections stay quiet). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin's key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject(['sessionProjections'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.
+`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit's `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the unit's previous projection (identity-stable projections stay quiet; the baseline advances with every change, heard or not). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin's key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject(['sessionProjections'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.
 
 ```ts cordis-catalog
 /**

docs/subsystems/session-projection.zh.md

@@ -86,9 +86,9 @@ interface ProjectionSnapshot {
  * Change-feed listener: one unit's served value changed for one session.
  * `value` is the schema-validated `view` output; `seq` is the unit's
  * watermark at emission (the seq of the event that caused the change). A
- * changed state whose raw `view` output is `Object.is`-identical to the last
- * delivered one does not fire, so a unit can buffer working fields in state
- * behind an identity-stable projection.
+ * changed state whose raw `view` output is `Object.is`-identical to the
+ * unit's previous projection does not fire, so a unit can buffer working
+ * fields in state behind an identity-stable projection.
  */
 type ProjectionChangeListener = (
   session: Session,
@@ -98,7 +98,7 @@ type ProjectionChangeListener = (
 ) => void
 ```
 
-`snapshot(session)` 完全同步：载体在切出页面切片的同一 tick 内读取它，因此 `asOfSeq` 使两次读取使用同一个序号。它只返回客户端视图，并在返回前通过各单元的 `viewSchema` 校验。`stateOf(session, key)` 可在不计算无关视图的情况下读取一份实时 host 状态；调用方不得修改这一借用引用。对于每个已提交事件，变更流会为每个状态*引用*已变化的客户端可见单元触发一次——除非原始 `view` 输出与变更流上一次交付的值 `Object.is` 相同，因此单元可以把工作字段缓冲在状态里，用身份稳定的投影保持安静；状态未变时，`apply` 必须返回同一引用。
+`snapshot(session)` 完全同步：载体在切出页面切片的同一 tick 内读取它，因此 `asOfSeq` 使两次读取使用同一个序号。它只返回客户端视图，并在返回前通过各单元的 `viewSchema` 校验。`stateOf(session, key)` 可在不计算无关视图的情况下读取一份实时 host 状态；调用方不得修改这一借用引用。对于每个已提交事件，变更流会为每个状态*引用*已变化的客户端可见单元触发一次——除非原始 `view` 输出与该单元上一次投影值 `Object.is` 相同（基线随每次变更前进，无论有无监听者），因此单元可以把工作字段缓冲在状态里，用身份稳定的投影保持安静，后来的监听者也不会错过任何值变化；状态未变时，`apply` 必须返回同一引用。
 
 ## 注册表：`ctx.sessionProjections`
 
@@ -180,7 +180,7 @@ Source: [`packages/session/session-projection-cache/src/index.ts`](../../package
 
 ### `ctx.sessionProjections` — `SessionProjectionRegistry`
 
-`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit's `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the last delivered one (identity-stable projections stay quiet). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin's key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject(['sessionProjections'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.
+`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit's `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the unit's previous projection (identity-stable projections stay quiet; the baseline advances with every change, heard or not). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin's key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject(['sessionProjections'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.
 
 ```ts cordis-catalog
 /**

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

@@ -1574,7 +1574,7 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
   {
     key: 'sessionProjections',
     summary: '`ctx.sessionProjections`: the projection unit table and its drive.',
-    description: '`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit\'s `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the last delivered one (identity-stable projections stay quiet). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin\'s key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject([\'sessionProjections\'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.',
+    description: '`ctx.sessionProjections`: the projection unit table and its drive. The service subscribes to `session/event` once; every committed event passes every registered unit\'s `apply` (eager drive), and a changed state reference in a client-visible unit notifies the change feed with the schema-validated view — unless the raw view output is `Object.is`-identical to the unit\'s previous projection (identity-stable projections stay quiet; the baseline advances with every change, heard or not). Cells build lazily — a unit registered after events flowed, or a session older than the registry, folds `init` over the in-memory log on first touch (event or read). Registration is an effect (disposer rides the calling fiber): an unloaded domain plugin\'s key disappears from snapshots and clients read it as capability absence. A host reader either declares `sessionProjections` in its plugin `inject` or fails explicitly when the registry or required key is absent. Contributors may preserve optional registration through `ctx.inject([\'sessionProjections\'], ...)`. Registrants sharing a key share one unit and are counted: the same tool package mounted in N agent presets registers N times, and the key survives until the last one unloads.',
     methods: [
       {
         signature: 'register< K extends keyof SessionProjectionMap, S extends SessionProjectionStateMap[K], >( definition: Omit<ProjectionDefinition<K, S>, \'wire\'> & { wire: NonNullable<ProjectionDefinition<K, S>[\'wire\']> }, ): () => void',

packages/session/session-projection/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/session/session-projection/README.md
-README.md: 0268f05ef49c27082478e19941e5b3888cbce46e
-README.zh.md: 286aeebf0ffdf5b5d1c4eeadc00d9df64c26daf7
+README.md: c498d6f163d704467f035f07e3da1ce1d484a163
+README.zh.md: eff47a64f2547e56642527cffb05e219d18397bf

packages/session/session-projection/README.md

@@ -78,7 +78,7 @@ This section explains the drive machinery and the unit contract; the observable
 
 ### Design concept
 
-The package is the Service Definition and drive role of a capability seam: the framework drives, the domain computes. The registry subscribes to `session/event` once; every committed event passes every registered unit's `apply` eagerly (cells build lazily on first touch). The change feed is gated on `Object.is` twice — a unit that returns the same state reference costs one call and nothing downstream, and a changed state whose raw `view` output is identical to the last delivered one stays quiet (so a unit can buffer working fields behind an identity-stable projection). Carriers read `snapshot()` in the same tick as their page slice, which is what makes `asOfSeq` one consistent cut; an accidentally async view returns a Promise and fails `wire.viewSchema.parse`.
+The package is the Service Definition and drive role of a capability seam: the framework drives, the domain computes. The registry subscribes to `session/event` once; every committed event passes every registered unit's `apply` eagerly (cells build lazily on first touch). The change feed is gated on `Object.is` twice — a unit that returns the same state reference costs one call and nothing downstream, and a changed state whose raw `view` output is identical to the unit's previous projection stays quiet, with the baseline advancing on every change, heard or not (so a unit can buffer working fields behind an identity-stable projection without silencing later listener generations). Carriers read `snapshot()` in the same tick as their page slice, which is what makes `asOfSeq` one consistent cut; an accidentally async view returns a Promise and fails `wire.viewSchema.parse`.
 
 ### Source map
 

packages/session/session-projection/README.zh.md

@@ -78,7 +78,7 @@ const { asOfSeq, values } = ctx.sessionProjections.snapshot(session)
 
 ### 设计理念
 
-本包是能力 seam 的 Service Definition 与驱动角色：框架负责驱动，领域负责计算。注册表只订阅一次 `session/event`；每个已提交事件都会主动经过每个已注册单元的 `apply`（cell 在首次触达时惰性构建）。变更流以 `Object.is` 把关两道——返回同一状态引用的单元只花一次调用、不产生任何下游工作；状态已变但原始 `view` 输出与上次交付相同的单元同样保持安静（单元因此可以把工作字段缓冲在身份稳定的投影之后）。载体在切出页面切片的同一 tick 内读取 `snapshot()`，`asOfSeq` 之所以是一个一致切面正系于此；误写成异步的 view 会返回 Promise，并被 `wire.viewSchema.parse` 拒绝。
+本包是能力 seam 的 Service Definition 与驱动角色：框架负责驱动，领域负责计算。注册表只订阅一次 `session/event`；每个已提交事件都会主动经过每个已注册单元的 `apply`（cell 在首次触达时惰性构建）。变更流以 `Object.is` 把关两道——返回同一状态引用的单元只花一次调用、不产生任何下游工作；状态已变但原始 `view` 输出与该单元上一次投影值相同的同样保持安静，且基线随每次变更前进、有无监听者都一样（单元因此可以把工作字段缓冲在身份稳定的投影之后，而不会静默掉后来监听者的值变化）。载体在切出页面切片的同一 tick 内读取 `snapshot()`，`asOfSeq` 之所以是一个一致切面正系于此；误写成异步的 view 会返回 Promise，并被 `wire.viewSchema.parse` 拒绝。
 
 ### 源码地图
 

packages/session/session-projection/src/index.ts

@@ -86,9 +86,9 @@ export interface ProjectionDefinition<
  * Change-feed listener: one unit's served value changed for one session.
  * `value` is the schema-validated `view` output; `seq` is the unit's
  * watermark at emission (the seq of the event that caused the change). A
- * changed state whose raw `view` output is `Object.is`-identical to the last
- * delivered one does not fire, so a unit can buffer working fields in state
- * behind an identity-stable projection.
+ * changed state whose raw `view` output is `Object.is`-identical to the
+ * unit's previous projection does not fire, so a unit can buffer working
+ * fields in state behind an identity-stable projection.
  */
 export type ProjectionChangeListener = (
   session: Session,
@@ -145,10 +145,11 @@ interface UnitCell {
   /** Seq of the last event passed through `apply` (regardless of change). */
   observedSeq: number
   /**
-   * Raw (pre-validation) `view` output the change feed last delivered, when
-   * it has delivered one. A changed state whose raw view is `Object.is` to
-   * this stays quiet, so a unit can buffer working fields in state by
-   * keeping its wire projection identity-stable.
+   * Raw (pre-validation) `view` output of the last changed state, stamped
+   * whether or not a listener heard it. A changed state whose raw view is
+   * `Object.is` to this stays quiet, so a unit can buffer working fields in
+   * state by keeping its wire projection identity-stable — and a listener
+   * subscribing later still sees every value transition since this baseline.
    */
   lastView?: { raw: unknown }
 }
@@ -177,7 +178,8 @@ interface Registration {
  * every registered unit's `apply` (eager drive), and a changed state
  * reference in a client-visible unit notifies the change feed with the
  * schema-validated view — unless the raw view output is `Object.is`-identical
- * to the last delivered one (identity-stable projections stay quiet).
+ * to the unit's previous projection (identity-stable projections stay quiet;
+ * the baseline advances with every change, heard or not).
  * Cells build lazily — a unit registered after events flowed, or a session
  * older than the registry, folds `init` over the in-memory log on first
  * touch (event or read). Registration is an effect (disposer rides the
@@ -639,13 +641,17 @@ export class SessionProjectionRegistry extends Service {
       const changed = !Object.is(next, cell.state)
       cell.state = next
       cell.observedSeq = event.seq
-      if (changed && registration.def.wire !== undefined && this.listeners.size > 0) {
+      if (changed && registration.def.wire !== undefined) {
         // Identity gate on the raw view: a changed state whose projection is
-        // reference-identical to the last delivered one stays quiet, so a
-        // unit can buffer working fields without spamming the feed.
+        // reference-identical to the previous one stays quiet, so a unit can
+        // buffer working fields without spamming the feed. The baseline is
+        // stamped on every change — listeners or none — so a later listener
+        // generation cannot be silenced by a value the unobserved state
+        // passed through and returned to.
         const raw = registration.def.wire.view(cell.state)
-        if (cell.lastView !== undefined && Object.is(cell.lastView.raw, raw)) continue
+        const identical = cell.lastView !== undefined && Object.is(cell.lastView.raw, raw)
         cell.lastView = { raw }
+        if (identical || this.listeners.size === 0) continue
         const value = registration.def.wire.viewSchema.parse(raw)
         for (const listener of this.listeners) {
           listener(session, registration.def.key as Extract<keyof SessionProjectionMap, string>, value, event.seq)

packages/session/session-projection/tests/registry.spec.ts

@@ -20,11 +20,13 @@ declare module '@deepseek-ai/dsh-session-projection/types' {
     'test/marks': MarksState
     'test/count': number
     'test/buffered': { marks: string[]; draft: string }
+    'test/label': string
   }
 
   interface SessionProjectionMap {
     'test/marks': { marks: string[] }
     'test/buffered': string[]
+    'test/label': string
   }
 }
 
@@ -149,6 +151,38 @@ describe('SessionProjectionRegistry drive', () => {
     expect(ctx.sessionProjections.snapshot(session).values['test/buffered']).toEqual(['a', 'b'])
   })
 
+  it('advances the dedup baseline while unobserved, so a later listener hears a return to an old value', async () => {
+    const { ctx, session } = await harness()
+    // A primitive-valued view compares by value under Object.is (the title
+    // unit's shape), which is exactly where a stale baseline could silence a
+    // real transition.
+    ctx.sessionProjections.register({
+      key: 'test/label',
+      stateSchema: z.string(),
+      init: () => '',
+      apply: (state, event) => (event.type === 'test/mark' ? event.data.marks[0] ?? '' : state),
+      wire: { viewSchema: z.string(), view: state => state },
+      stateVersion: 1,
+    })
+    const first: string[] = []
+    const stop = ctx.sessionProjections.onChanged((_session, key, value) => {
+      if (key === 'test/label') first.push(value as string)
+    })
+    mark(session, ['A'])
+    stop()
+    // Unobserved transition away from 'A'…
+    mark(session, ['B'])
+    // …then a new listener generation subscribes and the value returns: with
+    // a baseline frozen at 'A' this delivery would be silenced.
+    const second: string[] = []
+    ctx.sessionProjections.onChanged((_session, key, value) => {
+      if (key === 'test/label') second.push(value as string)
+    })
+    mark(session, ['A'])
+    expect(first).toEqual(['A'])
+    expect(second).toEqual(['A'])
+  })
+
   it('drives independently per session (cells are per-session watermarks)', async () => {
     const { ctx, session } = await harness()
     const other = ctx.sessions.create()