refactor(gui): dissolve the tool ring into per-view keyed slots

Four rounds of structural rework on the conversation surface, converging
on one registration model for the whole client:

- Review fixes: open() leaves the inject factory (SessionsService owns
  the semantic); ConversationService mounts via ctx.plugin(); the
  bespoke view registry retires into the 'conversation.view' list slot.
- Ring alignment: createChatView factory retired (components get
  everything through checkable shares at the register call site); the
  hand-rolled t/i18n threading is deleted wholesale — a future
  framework-level i18n will supply t as a standard prop keyed by slot
  name, so no interim manual channel.
- Toolview dissolution: ToolViewRegistry / ToolViewResolver /
  ToolViewOutlet / ctx.toolviews retire. Tool rows are entries of the
  'conversation.chat.toolview' keyed slot (scope: session) declared by
  the chat entry; ToolRowOwnerProps is the unified owner payload;
  GenericToolCard becomes the call-site fallback; registrants are plain
  plugins (inject ['slots','conversation'] as the load-order seam);
  session-dimension dispatch moves into components (useSessions reads
  parentId); trajectory/waterfall gain same-shape slots the day they
  render tool rows (RendersCheck rejects empty declarations). Slot
  names mirror the composition path (<domain>.<entry>.<hole>).
- Staging follows current: cell()/binding() are pure resolution
  (render-safe); the constructor subscribes to the list store and
  followCurrent opens the event window when the current session
  changes — staging IS the open signal, business verbs are the timing,
  React render/commit is decoupled from window lifecycle. A masked
  current (projection gap) keeps the stage untouched so deferred
  teardown semantics survive reconnects.

Agent Note: .agents/notes/implemented/architecture/
2026-07-23-toolview-dissolution.md (bilingual pair) records the
decision, the four rejected alternatives, and the accepted semantic
changes; the web client architecture note and packages/client/AGENTS.md
carry the current-state narrative.

Verified: typecheck 0, duplication 0 clones (478 files), full coverage
run 6190 passed with zero threshold errors, knip 0, doc-sync 24/24,
client aggregate tsc 0, render-count checks (one commit per chunk, zero
row re-renders under streaming) green.

packages/client/runtime/README.md

@@ -13,6 +13,6 @@ None; this package neither assembles nor sends a provider request.
 ## Known Limitations and Deferred Work
 
 - **`loader.unload` is a stub (throws not-implemented)** — the full chain (fiber dispose → registration cascade → style removal) lands with the HMR project.
-- **Scope teardown is watch-approximated** — the most recently resolved binding stands in for "who is watching"; a removed-while-watched session's scope survives until the watch moves away, not until true observer count reaches zero.
+- **Scope teardown is stage-driven, single-occupant today** — the staged session follows `list.current` exactly (staging is the open signal: the event window opens ⟺ the session is on stage); a removed-while-staged session's scope survives frozen until the stage moves on, not until true observer count reaches zero. Resolution (`cell()`/`binding()`/`scope()`) is pure addressing, render-safe. The staged state can widen to a multi-pane list when concurrent panes land.
 - **Value imports of this package from plugin bundles must use the `/client` subpath** — the bare package name is not in the loader externals table and inlines a second module instance, whose private scope-tag Symbol never matches (the empty-state P0 postmortem).
 - **`SessionSummary.title` is a display projection** — the wire summary carries no title yet; the cwd basename stands in, then the raw id.

packages/client/runtime/src/client/index.ts

@@ -51,7 +51,7 @@ export type { SessionId } from '@deepseek-ai/dsh-client-connection/client'
  */
 export type ClientContext = Context
 
-/** The conversation-snapshot selector hook (ConvViewProps/ToolViewProps take this). */
+/** The conversation-snapshot selector hook (ConvViewProps/ToolRowProps take this). */
 export type UseConversationSession = SnapshotSelectorHook<ConversationSnapshot>
 
 /**

packages/client/runtime/src/client/sessions/service.ts

@@ -5,13 +5,14 @@
  * slot-parity design), session scope tree (mintScope pattern: no-op plugin
  * Fiber + ctx.extend scope tag), stable SessionBinding cache, ancestry walk.
  *
- * Scope lifecycle is watch-driven: a scope is minted lazily on first
- * resolution; a session leaving the list tears its scope down only when
- * nobody is watching it. "Watched" is approximated as the most recently
- * resolved binding id — SessionProvider re-resolves on every selection
- * change (keyed remount), so a switch away always re-evaluates the deferred
- * teardown; a host-side death without list removal keeps the scope (frozen
- * read-only view).
+ * Scope lifecycle is stage-driven: a scope is minted lazily on first
+ * resolution (pure — resolution has no side effects and is render-safe);
+ * the event window and deferred teardown key off the STAGED session, which
+ * follows `list.current` exactly. Staging is the open signal: the window
+ * opens ⟺ the session is on stage (today the stage is `current`; the staged
+ * state can widen to a multi-pane list later). A session leaving the list
+ * tears its scope down immediately unless it is the staged one, whose scope
+ * survives frozen (read-only view) until the stage moves on.
  */
 import type { Context, Fiber } from 'cordis'
 import type { IApiClient, SessionId } from '@deepseek-ai/dsh-client-connection/client'
@@ -97,9 +98,14 @@ export class SessionsService {
   private readonly selection: SnapshotStore<{ sessionId?: SessionId }>
 
   private readonly scopes = new Map<SessionId, ScopeRecord>()
-  /** Most recently resolved binding id — the watch approximation for deferred teardown. */
+  /**
+   * The staged session id — follows `list.current` exactly, holding its last
+   * defined value across masked gaps (a transiently absent selection blanks
+   * `current` without moving the stage, so reconnect re-pulls and removals
+   * keep the staged scope's frozen view alive until the stage moves on).
+   */
   private watched: SessionId | undefined
-  /** Removed-while-watched sessions whose teardown waits for the watch to move away. */
+  /** Removed-while-staged sessions whose teardown waits for the stage to move away. */
   private readonly deferredRemovals = new Set<SessionId>()
 
   /**
@@ -115,6 +121,13 @@ export class SessionsService {
     // The manager owns wire truth; the store is its projection. Manager
     // notifications are already microtask-batched.
     this.manager.subscribe(() => { this.projectList() })
+    // Stage follower: every current write (open() and projection alike)
+    // re-evaluates staging, so startup restore (persisted selection validated
+    // by the projection) and reconnect resurfacing open their window with no
+    // dedicated code path. Safe to run synchronously inside the store notify:
+    // the follower writes no list state — session.open()'s synchronous prefix
+    // touches only session-side state and its own microtask-batched notifier.
+    this.list.subscribe(() => { this.followCurrent() })
     rootCtx.reflect.provide('sessions', this, undefined)
   }
 
@@ -152,35 +165,50 @@ export class SessionsService {
   }
 
   /**
-   * Resolve the stable session binding (SessionProvider's resolveBinding feed).
+   * Resolve the stable session binding (scope-addressed assembly feed). Pure
+   * resolution — no staging, no window side effects.
    * @param id - session id.
    * @returns binding, or undefined for a session neither listed nor already scoped.
    */
   binding(id: SessionId): SessionBinding | undefined {
-    const record = this.resolve(id)
-    if (record === undefined) return undefined
-    if (this.watched !== id) {
-      this.watched = id
-      this.sweepDeferred()
-    }
-    return record.binding
+    return this.resolve(id)?.binding
   }
 
   /**
    * Resolve the render-layer session cell (SessionProvider's feed through
-   * the renderer host; ctx never enters the render layer). Marks the session
-   * watched, same as {@link SessionsService.binding}.
+   * the renderer host; ctx never enters the render layer). Pure resolution —
+   * render-safe: SessionProvider calls this during render, so no staging, no
+   * window side effects (StrictMode double-invokes and concurrent discarded
+   * passes must stay free).
    * @param id - session id.
    * @returns cell, or undefined for a session neither listed nor already scoped.
    */
   cell(id: string): SessionCell | undefined {
-    const record = this.resolve(id as SessionId)
-    if (record === undefined) return undefined
-    if (this.watched !== id) {
-      this.watched = id as SessionId
-      this.sweepDeferred()
+    return this.resolve(id as SessionId)?.cell
+  }
+
+  /**
+   * Move the stage to the list's current session: sweep teardowns deferred
+   * behind the previous occupant and pull the new occupant's history window.
+   * Staging IS the open signal — the window opens ⟺ the session is on stage
+   * — and open() is idempotent (an in-flight or completed open no-ops; a
+   * failed one retries the next time current is touched).
+   */
+  private followCurrent(): void {
+    const current = this.list.getSnapshot().current
+    // A masked gap (current blanked while the selection's session is
+    // transiently absent) holds the stage: tearing down on the gap would
+    // destroy exactly the frozen scope the mask exists to preserve.
+    if (current === undefined || current === this.watched) return
+    this.watched = current
+    this.sweepDeferred()
+    const record = this.resolve(current)
+    /* v8 ignore next 3 -- defensive: current is always a listed id (open()
+     * validates and the projection masks absent selections), so resolve
+     * cannot miss; kept so a future current writer cannot crash the notify. */
+    if (record !== undefined) {
+      void record.binding.session.open()
     }
-    return record.cell
   }
 
   /**
@@ -246,7 +274,7 @@ export class SessionsService {
     this.pruneScopes(byId)
   }
 
-  /** Tear down scopes for removed sessions nobody watches; the watched one defers until the watch moves. */
+  /** Tear down scopes for removed sessions off stage; the staged one defers until the stage moves. */
   private pruneScopes(byId: Record<SessionId, SessionSummary>): void {
     for (const [id, record] of this.scopes) {
       if (byId[id] !== undefined) continue
@@ -268,11 +296,11 @@ export class SessionsService {
     this.rootCtx.get('slots')?.pruneStoreScope(id)
   }
 
-  /** Run deferred teardowns whose session is no longer watched (called when the watch moves). */
+  /** Run deferred teardowns whose session is no longer staged (called when the stage moves). */
   private sweepDeferred(): void {
     for (const id of [...this.deferredRemovals]) {
-      /* v8 ignore next -- defensive: only the watched id ever defers, and every
-       * watch move sweeps first, so the set cannot contain the id the watch just
+      /* v8 ignore next -- defensive: only the staged id ever defers, and every
+       * stage move sweeps first, so the set cannot contain the id the stage just
        * moved to; kept as a guard against future extra sweep call sites. */
       if (id === this.watched) continue
       // Still absent from the list? (A re-added id cancels the deferred teardown.)

packages/client/runtime/tests/sessions-service.spec.ts

@@ -2,8 +2,9 @@
  * SessionsService: list store projection (manager → {ids, byId, current}
  * with derived titles), the migrated current-selection account (open
  * validation, persisted mask semantics, cell resolution), scope-tree
- * lifecycle (lazy mint / frozen survival / removed teardown with watch
- * deferral), binding identity, ancestry walk, create.
+ * lifecycle (lazy mint / frozen survival / removed teardown with staged
+ * deferral — the stage follows list.current), binding identity, ancestry
+ * walk, create.
  */
 import { Context } from 'cordis'
 import { afterEach, describe, expect, it, vi } from 'vitest'
@@ -76,21 +77,21 @@ describe('scope tree', () => {
     expect(binding?.ctx).toBe(scoped)
   })
 
-  it('tears down an unwatched removed session but defers the watched one until the watch moves', async () => {
+  it('tears down an off-stage removed session but defers the staged one until the stage moves', async () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }, { id: 's2' }])
     const ctx1 = b.svc.scope(sid('s1'))
-    b.svc.binding(sid('s1')) // s1 is watched
-    b.svc.scope(sid('s2')) // s2 scoped but not watched
+    b.svc.open(sid('s1')) // s1 staged (current)
+    b.svc.scope(sid('s2')) // s2 scoped but off stage
 
-    await feedList(b, [{ id: 's1' }]) // s2 removed, unwatched: torn down
+    await feedList(b, [{ id: 's1' }]) // s2 removed, off stage: torn down
     expect(b.svc.scope(sid('s2'))).toBeUndefined()
 
-    await feedList(b, []) // s1 removed while watched: deferred, scope survives
+    await feedList(b, []) // s1 removed while staged (current masks): deferred, scope survives
     expect(b.svc.scope(sid('s1'))).toBe(ctx1)
 
     await feedList(b, [{ id: 's3' }])
-    b.svc.binding(sid('s3')) // watch moves: deferred teardown sweeps s1
+    b.svc.open(sid('s3')) // stage moves: deferred teardown sweeps s1
     expect(b.svc.scope(sid('s1'))).toBeUndefined()
   })
 
@@ -106,10 +107,10 @@ describe('scope tree', () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }])
     const scoped = b.svc.scope(sid('s1'))
-    b.svc.binding(sid('s1'))
-    await feedList(b, []) // removed while watched → deferred
-    await feedList(b, [{ id: 's1' }, { id: 's2' }]) // reappears
-    b.svc.binding(sid('s2')) // watch moves; sweep must NOT tear down the re-listed s1
+    b.svc.open(sid('s1'))
+    await feedList(b, []) // removed while staged → deferred
+    await feedList(b, [{ id: 's1' }, { id: 's2' }]) // reappears (current resurfaces, stage unchanged)
+    b.svc.open(sid('s2')) // stage moves; sweep must NOT tear down the re-listed s1
     expect(b.svc.scope(sid('s1'))).toBe(scoped)
   })
 })
@@ -168,15 +169,52 @@ describe('cell (render-layer session kit)', () => {
     expect(b.svc.cell('ghost')).toBeUndefined()
   })
 
-  it('moves the watch like binding(): switching cells sweeps a deferred removal', async () => {
+  it('cell()/binding() are pure resolution: no staging, no deferred sweep', async () => {
     const b = bench()
-    await feedList(b, [{ id: 's1' }])
-    b.svc.cell('s1') // watched
-    await feedList(b, []) // removed while watched → deferred, scope survives
+    await feedList(b, [{ id: 's1' }, { id: 's2' }])
+    b.svc.open(sid('s1')) // staged
+    b.svc.cell('s2') // resolution only — must NOT move the stage
+    b.svc.binding(sid('s2'))
+    await feedList(b, [{ id: 's2' }]) // s1 removed: still staged → deferred, scope survives
     expect(b.svc.scope(sid('s1'))).toBeDefined()
-    await feedList(b, [{ id: 's2' }])
-    b.svc.cell('s2') // watch moves → sweep tears s1 down
-    expect(b.svc.scope(sid('s1'))).toBeUndefined()
+  })
+
+  it('staging (current write) opens the session event window; resolution and re-staging do not re-pull', async () => {
+    const b = bench()
+    await feedList(b, [{ id: 's1' }, { id: 's2' }])
+    const historyCalls = () => b.api.calls.filter(c => c.method === 'session.history')
+    // Resolution is addressing, not staging: no window pull.
+    b.svc.scope(sid('s1'))
+    b.svc.cell('s1')
+    b.svc.binding(sid('s1'))
+    expect(historyCalls()).toHaveLength(0)
+    b.svc.open(sid('s1'))
+    expect(historyCalls().map(c => (c.payload as { sessionId: string }).sessionId)).toEqual(['s1'])
+    // Same current again: no second pull.
+    b.svc.open(sid('s1'))
+    expect(historyCalls()).toHaveLength(1)
+    // Stage moves: the new occupant opens.
+    b.svc.open(sid('s2'))
+    expect(historyCalls().map(c => (c.payload as { sessionId: string }).sessionId)).toEqual(['s1', 's2'])
+  })
+
+  it('startup restore: a persisted selection validated by the first projection opens its window unprompted', async () => {
+    const storage = new Map<string, string>([
+      ['dsh.sessions.current', JSON.stringify({ sessionId: 's1' })],
+    ])
+    vi.stubGlobal('localStorage', {
+      getItem: (k: string) => storage.get(k) ?? null,
+      setItem: (k: string, v: string) => { storage.set(k, v) },
+    })
+    try {
+      const b = bench()
+      expect(b.api.calls.filter(c => c.method === 'session.history')).toHaveLength(0)
+      await feedList(b, [{ id: 's1' }]) // projection validates the persisted id → current lands → stage follows
+      const historyCalls = b.api.calls.filter(c => c.method === 'session.history')
+      expect(historyCalls.map(c => (c.payload as { sessionId: string }).sessionId)).toEqual(['s1'])
+    } finally {
+      vi.unstubAllGlobals()
+    }
   })
 })
 
@@ -187,12 +225,13 @@ describe('slot-store scope prune hook', () => {
     b.ctx.reflect.provide('slots', { pruneStoreScope })
     await feedList(b, [{ id: 's1' }, { id: 's2' }])
     b.svc.scope(sid('s1'))
-    b.svc.binding(sid('s2')) // s2 watched
-    await feedList(b, []) // s1 unwatched → immediate drop; s2 watched → deferred
+    b.svc.scope(sid('s2'))
+    b.svc.open(sid('s2')) // s2 staged
+    await feedList(b, []) // s1 off stage → immediate drop; s2 staged → deferred
     expect(pruneStoreScope).toHaveBeenCalledWith('s1')
     expect(pruneStoreScope).not.toHaveBeenCalledWith('s2')
     await feedList(b, [{ id: 's3' }])
-    b.svc.binding(sid('s3')) // watch moves → deferred sweep drops s2
+    b.svc.open(sid('s3')) // stage moves → deferred sweep drops s2
     expect(pruneStoreScope).toHaveBeenCalledWith('s2')
   })
 
@@ -242,44 +281,46 @@ describe('coverage tails (branch duals)', () => {
     expect(byId[sid('empty-cwd')]?.title).toBe('empty-cwd')
   })
 
-  it('binding for an unknown session returns undefined without moving the watch', async () => {
+  it('binding for an unknown session returns undefined and leaves the staged scope intact', async () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }])
-    b.svc.binding(sid('s1'))
+    b.svc.open(sid('s1'))
     expect(b.svc.binding(sid('ghost'))).toBeUndefined()
-    // Watch unchanged: removing s1 defers (still watched), proving the ghost lookup did not steal the watch.
+    // Stage unchanged: removing s1 defers (still staged), proving the ghost lookup touched nothing.
     await feedList(b, [])
     expect(b.svc.scope(sid('s1'))).toBeDefined()
   })
 
-  it('sweep skips the id that is itself still watched and tolerates a scope record already gone', async () => {
+  it('a masked current gap holds the stage (no teardown, no re-open) until the stage moves', async () => {
     const b = bench()
     await feedList(b, [{ id: 's1' }])
-    b.svc.binding(sid('s1'))
-    await feedList(b, []) // deferred removal of the watched id
-    // Re-resolving the SAME watched id: sweep runs but must skip it (watched-continue branch).
-    expect(b.svc.binding(sid('s1'))).toBeDefined()
+    b.svc.open(sid('s1'))
+    const historyCalls = () => b.api.calls.filter(c => c.method === 'session.history')
+    expect(historyCalls()).toHaveLength(1)
+    await feedList(b, []) // removed while staged: current masks to undefined, stage holds → deferred
     expect(b.svc.scope(sid('s1'))).toBeDefined()
+    // Resurfacing re-projects current = s1: same stage occupant, no second pull.
+    await feedList(b, [{ id: 's1' }])
+    expect(historyCalls()).toHaveLength(1)
+    expect(b.svc.list.getSnapshot().current).toBe('s1')
   })
 
-  it('sweep hits both deferral edges: watched-id skip and an already-vacated scope record', async () => {
+  it('sweep hits both deferral edges: staged-id skip and an already-vacated scope record', async () => {
     const b = bench()
     await feedList(b, [{ id: 'a' }, { id: 'b' }])
-    b.svc.binding(sid('a'))
-    b.svc.binding(sid('b')) // watch: b; both scoped
-    await feedList(b, []) // a removed unwatched → torn immediately; b removed watched → deferred
-    // Move the watch to a THIRD id while b stays deferred: sweep now walks a
-    // set containing b (torn) — and the watched-continue branch fires when the
-    // deferral set still holds the current watch target.
+    b.svc.scope(sid('a'))
+    b.svc.open(sid('b')) // stage: b; both scoped
+    await feedList(b, []) // a removed off stage → torn immediately; b removed staged → deferred
+    // Move the stage to a THIRD id while b stays deferred: sweep walks a set
+    // containing b (torn).
     await feedList(b, [{ id: 'c' }])
-    b.svc.binding(sid('c'))
+    b.svc.open(sid('c'))
     expect(b.svc.scope(sid('b'))).toBeUndefined()
-    // Deferral for an id whose record was never minted: force-add via removed
-    // list state (scope teardown raced) — sweep must tolerate the missing record.
-    await feedList(b, [])
-    b.svc.binding(sid('c')) // c now watched+removed → deferred
+    // Deferral for an id whose record was never minted: force the deferral
+    // via removed list state — sweep must tolerate the missing record.
+    await feedList(b, []) // c removed while staged → deferred (scope exists)
     await feedList(b, [{ id: 'd' }])
-    b.svc.binding(sid('d')) // sweep tears c
+    b.svc.open(sid('d')) // sweep tears c
     expect(b.svc.scope(sid('c'))).toBeUndefined()
   })