Merge origin/master into web-permission-sandbox

39 conflicts resolved per the reattachment plan (missions worktree-projbiz
0728-1859): baseline wins for deleted packages (host/runtime, old ui/acp,
ui-sidebar Rows/tree) and retired specs; unions for wire-layer exports and
client summary fields; the approval takeover, waitingApprovals tracking, and
PendingApproval domain face carry over onto the master structure. The two
new host specs follow the runtime->apiproxy rename. Dead PR-side wiring
(ConversationInjected permissions/setPermission spread, InputBar controls
prop, boot.ts sandbox composition) resolves to master and its replacement
lands in follow-up commits.

packages/client/runtime/src/client/agents/scope.ts

@@ -0,0 +1,70 @@
+/**
+ * Client Agent-scope primitive: mint a Cordis context tagged with the owning
+ * Agent's identity. The mechanism mirrors the host `dsh-scope` architecture
+ * (no-op plugin fiber + context tag + `Context.filter` routing predicate);
+ * the shape deliberately diverges: the filter lives on the actx itself
+ * instead of a separate carrier object, so scoped dispatch is plain cordis —
+ * `actx.bail(actx, event, payload)` / `actx.emit(actx, ...)` — with no
+ * wrapper. The host needs a detached carrier because its dispatch subject is
+ * the business Agent object; client scope events carry only ids, so the
+ * actx is the natural subject. The second divergence stands: the scope key
+ * is the branded `SessionId` (value compared), not an object identity — the
+ * agent and its session share one id (1:1, same axis; no separate AgentId
+ * brand), and a client scope's identity IS that wire id. Third divergence,
+ * deliberate: the client scopes the Agent IDENTITY, not a live Agent object
+ * — a cold session's host Agent is already disposed while its client actx
+ * stays alive for history viewing.
+ */
+import { Context as CordisContext } from 'cordis'
+import type { Context, Fiber } from 'cordis'
+import type { SessionId } from '@deepseek-ai/dsh-client-connection/client'
+
+/** Context tag written by {@link createScope}. */
+const kScope = Symbol('dsh.client.scope')
+
+/** A minted Agent scope and its disposal boundary. */
+export interface AgentScopeHandle {
+  /**
+   * Tagged context: scope-owned registrations and scoped dispatch both go
+   * through it (passing it as the dispatch subject routes to this agent's
+   * tagged listeners plus every untagged one).
+   */
+  ctx: Context
+  /** Backing fiber (dispose tears down every scope-owned registration). */
+  fiber: Fiber
+}
+
+/** Shared no-op plugin backing each Agent scope fiber. */
+function agentScope(): void {}
+
+/**
+ * Mint an Agent scope under `ctx`: a no-op plugin fiber whose context
+ * carries the agent tag and the dispatch filter — untagged listeners are
+ * admitted globally, tagged listeners only for a matching agent.
+ * Registrations through the returned ctx dispose with the fiber.
+ * @param ctx - client root context the scope fiber mounts under.
+ * @param key - owning agent identity (the routing tag; agent id === session id).
+ * @returns the tagged context and its backing fiber.
+ */
+export function createScope(ctx: Context, key: SessionId): AgentScopeHandle {
+  const fiber = ctx.plugin(agentScope)
+  return {
+    fiber,
+    ctx: fiber.ctx.extend({
+      [kScope]: key,
+      [CordisContext.filter](listenerCtx: Context): boolean {
+        const tag = scopeOf(listenerCtx)
+        return tag === undefined || tag === key
+      },
+    }),
+  }
+}
+
+/**
+ * Read the nearest agent tag inherited by a context.
+ * @param ctx - any client context.
+ * @returns its agent identity (the session id), or undefined for root contexts.
+ */
+export function scopeOf(ctx: Context): SessionId | undefined {
+  return (ctx as Context & { [kScope]?: SessionId })[kScope]
+}

packages/client/runtime/src/client/contract/store.ts

@@ -161,11 +161,7 @@ function deepFreeze(value: unknown): void {
   }
 }
 
-// ---- defineStore shell (slot terminal design §4) ----
-// The type authority is ui-slots' store family (create(scopeKey?) and
-// clearPersisted() included); this module houses only the engine-backed
-// implementation. The one engine-side widening left: instances expose the
-// raw engine store for framework/test surfaces.
+// ui-slots owns the contract; this module supplies the engine implementation.
 
 /** A live engine instance: the contract instance plus the raw engine store. */
 export interface EngineStoreInstance<T, A extends ActionsDecl<T>> extends StoreInstance<T, A> {

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

@@ -1,43 +1,45 @@
-/**
- * Browser half: the whole runtime contract surface (api-contracts v3 §4) —
- * SlotsService (declaration ledger + renderer seam + store axis, built-in
- * 'root'), SessionsService (list store + current selection + scope tree +
- * object layer), and the cordis Context/Events merges. apply mounts
- * ctx.slots + ctx.sessions and wires the connection stream loop into the
- * object layer. A static-arrival entry: the web shell bundles this module
- * and mounts it through the host graph (module loading lives in
- * @deepseek-ai/dsh-client-modules, entry governance in the vendored Loader).
- */
+/** Browser runtime services for slots, sessions, workspaces, and connection-stream delivery. */
 import type { Context } from 'cordis'
 import type { ConnectionHandle, SessionId } from '@deepseek-ai/dsh-client-connection/client'
-import type { SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
+import type { MaybeSnapshotSelectorHook, SnapshotSelectorHook } from '@deepseek-ai/dsh-client-ui-slots'
 import { SlotsService } from './slots.ts'
 import { SessionsService } from './sessions/service.ts'
 import type { SessionListState } from './sessions/service.ts'
+import { WorkspacesService } from './workspaces/service.ts'
 import type { ConversationSnapshot, RunningToolCall, ToolResultNode } from './sessions/conversation.ts'
+import type { UseProjection } from './sessions/projection-store.ts'
 
 export { SlotsService } from './slots.ts'
-// RootOwnerProps rides the 'root' SlotMap row (both migrated here from
-// ui-layout: the framework slot is declared by the framework package).
 export type { RootOwnerProps } from './slots.ts'
-export { SessionsService, scopeOf } from './sessions/service.ts'
+export { SessionCreateError, SessionsService, scopeOf, workspaceTitleOf } from './sessions/service.ts'
+export { createScope } from './agents/scope.ts'
+export type { AgentScopeHandle } from './agents/scope.ts'
+export { WorkspaceCreateError, WorkspacesService } from './workspaces/service.ts'
 export type { Session } from './sessions/session.ts'
-export type { SessionBinding, SessionListState, SessionSummary } from './sessions/service.ts'
-// The snapshot-store engine lives here since the store migration (the data
-// layer owns its substrate; web-react is React glue only). The './client'
-// main export is the single serving door — no store subpath.
+export type {
+  SessionBinding, SessionListState, SessionProvideContribution, SessionProvideDescriptor, SessionSummary,
+} from './sessions/service.ts'
+export type { SessionListPhase } from './sessions/manager.ts'
+export type { WorkspaceListPhase } from './workspaces/manager.ts'
+export type { WorkspaceListState } from './workspaces/service.ts'
+export type { WorkspaceId, WorkspaceView } from '@deepseek-ai/dsh-client-connection/client'
+// Runtime owns the snapshot store; web-react only binds it to React.
 export { createSnapshotStore, defineStore, shallowEqual } from './contract/store.ts'
 export type {
   EngineStoreHandle, EngineStoreInstance, ObservableSnapshot, SnapshotStore,
 } from './contract/store.ts'
 export type {
-  AssistantBlock, AssistantMessageNode, ContextMessageNode, ConversationNode, ConversationSnapshot,
-  RunningToolCall, SteeringMessageNode,
-  ToolResultNode, UnknownSurfaceNode, UserMessageNode,
+  AssistantBlock, AssistantMessageNode, CodeSubCall, CommandNode, ComposerPhase, ContextMessageNode, ConversationNode,
+  ConversationSnapshot, QueuedMessage, RunningToolCall,
+  SteeringMessageNode, TodoItem, ToolResultNode, UnknownSurfaceNode, UserMessageNode,
 } from './sessions/conversation.ts'
-// PendingWait is a value export: tests construct fixture waits directly.
 export { PendingWait } from './sessions/pending.ts'
 export type { PendingInteraction, PendingKind, PendingPayloads } from './sessions/pending.ts'
+// Projection value store (session-projection RFC, push model): host-computed
+// whole values per key; domains ship projection support with zero client code.
+export type {
+  ProjectionsBaseline, ProjectionValueStore, SessionProjectionMap, UseProjection,
+} from './sessions/projection-store.ts'
 export type { PermissionOption, SessionId } from '@deepseek-ai/dsh-client-connection/client'
 
 /** The permission select material as the object layer serves it to UI plugins. */
@@ -48,16 +50,7 @@ export interface PermissionSelect {
   currentValue: string
 }
 
-// ---- Narrowed aliases (the single narrowing point of the slot type chain:
-// ui-slots/web-react stay generic and dependency-inverted; the client-tree
-// concrete types live here, where their subjects live) ----
-
-/**
- * The client cordis context face: the base Context plus the service keys
- * this package's declaration merge contributes (slots/sessions/loader) and
- * every later plugin's merge. A plain alias — the merges land on Context
- * itself inside the client program; the name marks intent at consumer seams.
- */
+/** Client-side Cordis context after declaration merging. */
 export type ClientContext = Context
 
 /** The conversation-snapshot selector hook (ConvViewProps/ToolRowProps take this). */
@@ -77,15 +70,25 @@ declare module '@deepseek-ai/dsh-client-ui-slots' {
    * every session-scope slot component receives these from the framework.
    */
   interface SessionStandardProps {
-    /** Selector hook over this session's conversation snapshot. */
     useSession: SnapshotSelectorHook<ConversationSnapshot>
     /** The framework-resolved session id (owners never pass it). */
     sessionId: SessionId
+    /** The fifth framework hook seat: key-addressed projection reader (undefined = capability absent). */
+    useProjection: UseProjection
   }
-  /** Global standard kit, real members: the session-list hook every slot component receives. */
+  /** Standard kit for slots that remain mounted while current session changes. */
+  interface SessionMaybeStandardProps {
+    useSession: MaybeSnapshotSelectorHook<ConversationSnapshot>
+    /** Current session id; absent in the no-session state. */
+    sessionId: SessionId | undefined
+    /** Key-addressed projection reader; every key reads absent while no session is current. */
+    useProjection: UseProjection
+  }
+  /** Props injected into every global slot component. */
   interface GlobalStandardProps {
-    /** Selector hook over the session list snapshot (`current` included — the arbitrated selection seat). */
     useSessions: SnapshotSelectorHook<SessionListState>
+    /** Selector hook over real Workspaces and their independent baseline lifecycle. */
+    useWorkspaces: SnapshotSelectorHook<import('./workspaces/service.ts').WorkspaceListState>
   }
 }
 
@@ -97,28 +100,57 @@ declare module 'cordis' {
      * @param key - the mutated SlotMap key.
      */
     'slots/changed'(key: string): void
+    /**
+     * The host command registry changed (host/commands-changed passthrough).
+     * Pure invalidation signal: subscribers refetch `command.list` in the
+     * background rather than diffing.
+     * @mode emit
+     */
+    'commands/changed'(): void
+    /**
+     * A connection generation was (re-)established. Wire-derived caches must
+     * treat their state as stale and repull (commands directory; the queue
+     * mirrors reset themselves through the session resync path).
+     * @mode emit
+     */
+    'connection/reset'(): void
   }
   interface Context {
     slots: import('./slots.ts').SlotsService
     sessions: import('./sessions/service.ts').SessionsService
+    workspaces: import('./workspaces/service.ts').WorkspacesService
   }
 }
 
 /** Required services: the wire handle mounted by the connection plugin. */
 export const inject = ['connection']
 
-/**
- * Client plugin body: mount slots + sessions, start the stream loop.
- * @param ctx - client cordis context.
+/** Mounts the browser runtime services and connection stream.
+ * @param ctx - Client Cordis context.
  */
 export function apply(ctx: Context): void {
   ctx.plugin(SlotsService)
   const connection = ctx.get('connection') as ConnectionHandle
   const sessions = new SessionsService(ctx, connection.api)
+  const workspaces = new WorkspacesService(ctx, connection.api, sessions)
+  ctx.effect(
+    () => workspaces.startInitialSelection(),
+    'runtime: initial Workspace selection',
+  )
   const loop = connection.start({
-    onMuxEnvelope: (envelope) => { sessions.manager.handleMuxEnvelope(envelope) },
-    onHostEnvelope: (envelope) => { sessions.manager.handleHostEnvelope(envelope) },
-    onConnected: () => { sessions.manager.handleConnected() },
+    onMuxEnvelope: (envelope) => { sessions.handleMuxEnvelope(envelope) },
+    onHostEnvelope: (envelope) => {
+      sessions.handleHostEnvelope(envelope)
+      workspaces.handleHostEnvelope(envelope)
+      // Typed-event bridge: the session layer ignores registry frames (no
+      // session routing); consumers (command directory caches) subscribe on ctx.
+      if (envelope.payload.type === 'host/commands-changed') ctx.emit('commands/changed')
+    },
+    onConnected: () => {
+      sessions.handleConnected()
+      workspaces.handleConnected()
+      ctx.emit('connection/reset')
+    },
   })
   ctx.effect(() => () => { loop.stop() }, 'runtime: connection stream loop')
 }

packages/client/runtime/src/client/ordered-baseline.ts

@@ -0,0 +1,43 @@
+/**
+ * Merge an authoritative baseline without moving identities already visible to
+ * the client. Baseline-only identities are inserted relative to the nearest
+ * following known identity; identities absent from the baseline are removed.
+ *
+ * @param current - the established client order.
+ * @param baseline - the latest authoritative rows.
+ * @param keyOf - stable identity selector.
+ * @returns baseline-valued rows with the established relative order retained.
+ */
+export function mergeOrderedBaseline<T>(
+  current: readonly T[],
+  baseline: readonly T[],
+  keyOf: (value: T) => unknown,
+): T[] {
+  const baselineByKey = new Map<unknown, T>()
+  for (const value of baseline) baselineByKey.set(keyOf(value), value)
+
+  const merged = current
+    .map(value => baselineByKey.get(keyOf(value)))
+    .filter((value): value is T => value !== undefined)
+  const mergedKeys = new Set(merged.map(keyOf))
+
+  for (let index = 0; index < baseline.length; index++) {
+    const value = baseline[index]
+    /* v8 ignore next -- dense-array guard: index is bounded by baseline.length. */
+    if (value === undefined || mergedKeys.has(keyOf(value))) continue
+    let insertion = merged.length
+    for (let following = index + 1; following < baseline.length; following++) {
+      const candidate = baseline[following]
+      /* v8 ignore next -- dense-array guard: following is bounded by baseline.length. */
+      if (candidate === undefined) continue
+      const known = merged.findIndex(item => keyOf(item) === keyOf(candidate))
+      if (known !== -1) {
+        insertion = known
+        break
+      }
+    }
+    merged.splice(insertion, 0, value)
+    mergedKeys.add(keyOf(value))
+  }
+  return merged
+}

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

@@ -3,10 +3,16 @@
 // substructures keep their references (the React.memo premise). callId/approvalId stay plain
 // string here (narrow to real brands when convenient).
 
+import type { CommandId } from '@deepseek-ai/dsh-commands/brand'
 import type { ContentBlock } from '@deepseek-ai/dsh-llm/types'
-import type { RpcError, SessionId, ToolCallView, ToolResultView } from '@deepseek-ai/dsh-client-connection/client'
+import type { TodoItem } from '@deepseek-ai/dsh-session/types'
+import type {
+  RpcError, SessionId, ToolCallView, ToolResultView,
+} from '@deepseek-ai/dsh-client-connection/client'
 import type { PendingInteraction } from './pending.ts'
 
+export type { TodoItem }
+
 /** Assistant content blocks sorted by what the UI cares about
  *  (text body / collapsible reasoning / tool-call card head / other fallback). */
 export type AssistantBlock =
@@ -82,7 +88,6 @@ export interface ContextMessageNode {
   time: number
   content: readonly ContentBlock[]
   source: unknown
-  meta?: unknown
 }
 
 /** A tool result paired (when in-window) with its call head. */
@@ -116,6 +121,31 @@ export interface UnknownSurfaceNode {
   data: unknown
 }
 
+/**
+ * One slash-command lifecycle folded from the log-only `command/run` /
+ * `command/done` pair (paired by commandId, mirroring tool call↔result).
+ * Log-only events never enter the surface fold, so the FoldAdapter indexes
+ * them separately and merges the nodes into the flow by seq. A window cut
+ * between the pair soft-falls like tool pairs: a done with no in-window run
+ * still builds a node (name/args null), and a run with no done renders as
+ * still executing.
+ */
+export interface CommandNode {
+  kind: 'command'
+  /** Seq of the command/run event; the done event's seq when only the done is in-window. */
+  seq: number
+  /** Unix epoch ms of the anchoring event. */
+  time: number
+  /** Pairing id minted by the host executor. */
+  commandId: CommandId
+  /** Command name (run payload's structured field); null when the run fell outside the window. */
+  name: string | null
+  /** Verbatim rawInput after the name, separator whitespace included (run payload); null when the run fell outside the window. */
+  args: string | null
+  /** Settlement outcome (done payload); null while the command is still executing. */
+  outcome: { kind: 'success' | 'error'; text?: string } | null
+}
+
 /** Finalized conversation node union (kind discriminates; seq is the React key). */
 export type ConversationNode =
   | UserMessageNode
@@ -123,8 +153,24 @@ export type ConversationNode =
   | SteeringMessageNode
   | ContextMessageNode
   | ToolResultNode
+  | CommandNode
   | UnknownSurfaceNode
 
+/**
+ * One `run_code` sub-dispatch materialized in the native call-block shapes so
+ * every consumer (tool rows, details panel) renders it through the exact
+ * components that render a native call: a started-but-unsettled sub-call is a
+ * {@link RunningToolCall} (rows derive the running state from the shape,
+ * exactly as for native calls) and its `tool/code-dispatch` settlement
+ * replaces it in place with the {@link ToolResultNode} form. Never part of
+ * the surface `nodes` flow — sub-calls live under their parent via
+ * {@link ConversationSnapshot.codeDispatches}. `callId` is the deterministic
+ * sub-call id (`<parent>:code:<n>`); the call side carries the sub-tool name
+ * and its JSON-stringified logged arguments; `content`/`isError` are the
+ * settled sub-call's complete logged outcome.
+ */
+export type CodeSubCall = RunningToolCall | ToolResultNode
+
 /** In-flight tool card material: tool/call seen, tool/result not yet. */
 export interface RunningToolCall {
   callId: string
@@ -139,6 +185,12 @@ export interface RunningToolCall {
 }
 
 
+/** One queued-message row mirrored from `session/queued` frames (key: the enqueueing prompt's rpcId when wire-sourced). */
+export interface QueuedMessage {
+  readonly key: string
+  readonly preview: string
+}
+
 /** In-progress assistant output (chunk accumulator product). */
 export interface PartialAssistant {
   turn: number
@@ -149,6 +201,28 @@ export interface PartialAssistant {
 /** History-open lifecycle of a Session window. */
 export type OpenState = 'cold' | 'loading' | 'open' | 'error'
 
+/**
+ * Input-area shape of an OPEN session, derived at snapshot assembly (the one
+ * place that knows the predicate — consumers switch, never re-derive):
+ *
+ * - `blank`: no activity ever (no nodes, no partial, not running, no pending
+ *   waits, no prompt attempt) — the UI renders the blank-session guidance
+ *   hero.
+ * - `engaging`: the first prompt was initiated but no content landed yet —
+ *   the UI holds the composer through the accept → running → first-event
+ *   frames. Entered synchronously before prompt()'s first await.
+ * - `active`: content exists (nodes, partial, running turn, or pending
+ *   waits) — the ordinary conversation view.
+ *
+ * Monotone within a session object: blank → engaging → active, no returns.
+ * A failed first prompt stays `engaging` (composer + error strip — retry
+ * semantics; bouncing back to the hero would discard the error context).
+ * Sessions whose window is not open (`loading`/`error`) are outside phase
+ * jurisdiction: consumers branch on {@link ConversationSnapshot.openState}
+ * first (phase still reports `active`-ish facts but must not be rendered).
+ */
+export type ComposerPhase = 'blank' | 'engaging' | 'active'
+
 /** Send/stop failure surfaced in the input error strip; op picks the user-facing copy (发送失败 vs 停止失败). */
 export interface PromptError {
   op: 'send' | 'stop'
@@ -164,8 +238,19 @@ export interface ConversationSnapshot {
   foldDegraded: boolean
   partial: PartialAssistant | null
   runningCalls: readonly RunningToolCall[]
+  /**
+   * `run_code` sub-dispatches grouped under their parent callId, in dispatch
+   * order. Populated from in-window `tool/code-dispatch` events (live and
+   * replay identically); the per-parent array reference is stable across
+   * unrelated snapshot swaps (memo premise, same regime as `nodes`).
+   */
+  codeDispatches: ReadonlyMap<string, readonly CodeSubCall[]>
   pending: readonly PendingInteraction[]
+  /** Read-only inbox mirror (session/queued frames + mux-open baseline; cleared by the leave-running flip). */
+  queue: readonly QueuedMessage[]
   running: boolean
+  /** Input-area shape (see {@link ComposerPhase}); derived here, switched on by consumers. */
+  composerPhase: ComposerPhase
   /** Set after host/session-removed; the UI grays out and disables input. */
   removed: boolean
   openState: OpenState
@@ -173,5 +258,16 @@ export interface ConversationSnapshot {
   hasMore: boolean
   loadingOlder: boolean
   promptError: PromptError | null
+  /**
+   * Whether this session still has an empty log (no user message yet).
+   * Mirrors the host summary's derived blank bit: seeded from `session.list`
+   * / the `host/session-added` frame, flipped false by the first ACCEPTED
+   * prompt locally (on the RPC success response — acceptance proves the
+   * user message is in the host log; a rejected first prompt keeps the
+   * session blank and reusable) and by any `running: true` status remotely,
+   * and re-aligned by every list re-pull (the summary stays authoritative).
+   * Blank sessions are hidden from session lists and reused by New Session.
+   */
+  blank: boolean
   lastAgentError: string | null
 }

packages/client/runtime/src/client/sessions/fold-adapter.ts

@@ -8,8 +8,9 @@ import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 // go through it — the package root points at lib/index.js (needs a build) which the vite
 // browser bundle cannot resolve; surface.ts has no Node dependencies.
 import { SurfaceManager, isSurfaceEligibleType } from '@deepseek-ai/dsh-session/surface'
+import type { CommandId } from '@deepseek-ai/dsh-commands/brand'
 import type { ToolCallView, ToolEventView, ToolResultView } from '@deepseek-ai/dsh-client-connection/client'
-import type { ConversationNode } from './conversation.ts'
+import type { CommandNode, ConversationNode } from './conversation.ts'
 import { toAssistantBlocks } from './conversation.ts'
 
 /** In-window tool/call index entry (result-card backfill + runningCalls material). */
@@ -24,10 +25,10 @@ export interface CallIndexEntry {
   callView: ToolCallView | null
 }
 
-/** Non-surface-eligible sentinel event (safely skipped by surfaceOpOf's undefined branch).
- *  'noop/padding' is not a real event type on purpose: a genuine type with fake data would
- *  surface as garbage the day anyone adds handling for it (design §D.1; the cast is the one
- *  place a synthetic event enters the window). */
+/** Non-surface sentinel used to preserve paged-window sequence offsets.
+ * `noop/padding` is deliberately not a real event type, so it cannot acquire
+ * surface behavior; this cast is the only synthetic event entry point.
+ */
 function paddingEvent(seq: number): SessionEvent {
   return { type: 'noop/padding', seq, time: 0, data: {} } as unknown as SessionEvent
 }
@@ -40,6 +41,14 @@ function materializeNode(
 ): ConversationNode {
   switch (event.type) {
     case 'user/message':
+      // Injected context (plugin/goal source) folds to a context node, not a
+      // user message; only a direct human prompt is a user node.
+      if (event.data.source.kind !== 'user') {
+        return {
+          kind: 'context', seq: event.seq, time: event.time,
+          content: event.data.content, source: event.data.source,
+        }
+      }
       return {
         kind: 'user', seq: event.seq, time: event.time,
         content: event.data.content, source: event.data.source,
@@ -48,34 +57,30 @@ function materializeNode(
       return {
         kind: 'assistant', seq: event.seq, time: event.time,
         turn: event.data.turn, step: event.data.step,
-        blocks: toAssistantBlocks(event.data.content), usage: event.data.usage,
+        blocks: toAssistantBlocks(event.data.message.content), usage: event.data.usage,
       }
     case 'steering/message':
       return {
         kind: 'steering', seq: event.seq, time: event.time, turn: event.data.turn,
-        content: event.data.content, source: event.data.source,
-      }
-    case 'context/message':
-      return {
-        kind: 'context', seq: event.seq, time: event.time,
-        content: event.data.content, source: event.data.source,
-        meta: event.data.meta,
+        content: event.data.message.content, source: event.data.message.source,
       }
     case 'tool/result': {
-      const call = callIndex.get(String(event.data.callId))
+      const result = event.data.message.content[0]
+      const callId = String(event.data.message.source.callId)
+      const call = callIndex.get(callId)
       return {
         kind: 'tool-result', seq: event.seq, time: event.time,
-        callId: String(event.data.callId),
+        callId,
         call: call ? { name: call.name, argsRaw: call.argsRaw } : null,
         callTime: call?.time ?? null,
-        content: event.data.content, isError: event.data.isError,
+        content: result.content, isError: result.isError === true,
         ...(event.data.error !== undefined ? { error: event.data.error } : {}),
         meta: event.data.meta,
         callView: call?.callView ?? null,
         resultView,
       }
     }
-    /* v8 ignore next 2 -- defensive arm: fold output only carries the five
+    /* v8 ignore next 2 -- defensive arm: fold output only carries the four
     surface-eligible types, and each has a case above; reachable only if core
     adds an eligible type. */
     default:
@@ -97,6 +102,15 @@ export class FoldAdapter {
   private callIdx = new Map<string, CallIndexEntry>()
   /** Wire result views keyed by the tool/result event's seq (views ride the envelope, not the event). */
   private resultViews = new Map<number, ToolResultView>()
+  /**
+   * Command lifecycle nodes by commandId (insertion = run order). The
+   * `command/run`/`command/done` pair is log-only, so the surface fold never
+   * emits it; this index folds the pair (done settles its run's node in
+   * place) and nodes() merges the products into the flow by seq. Window cuts
+   * soft-fall like tool pairs: a done with no in-window run still builds a
+   * node.
+   */
+  private commandIdx = new Map<string, CommandNode>()
   /** Window revision (bumped on reset/append) keying the nodes() result cache: an unchanged
    *  window returns the previous ARRAY reference, not just cached elements — the snapshot's
    *  reference-stability contract (§A.9.4) starts here. */
@@ -126,10 +140,14 @@ export class FoldAdapter {
     this.degraded = false
     this.callIdx = new Map()
     this.resultViews.clear()
+    this.commandIdx = new Map()
     for (let i = 0; i < events.length; i++) {
       const event = events[i]
       /* v8 ignore next -- dense-array guard: i stays within events.length, so the undefined arm needs a sparse array no caller builds. */
-      if (event !== undefined) this.indexCall(event, views?.[i])
+      if (event !== undefined) {
+        this.indexCall(event, views?.[i])
+        this.indexCommand(event)
+      }
     }
   }
 
@@ -143,6 +161,7 @@ export class FoldAdapter {
     this.rev++
     this.padded.push(event)
     this.indexCall(event, view)
+    this.indexCommand(event)
   }
 
   /**
@@ -178,7 +197,23 @@ export class FoldAdapter {
       this.nodeCache.set(seq, node)
       out.push(node)
     }
-    const value = { nodes: out, degraded: this.degraded }
+    // Command nodes fold outside the surface (log-only events); merge by seq.
+    // Both inputs are seq-ascending (surface order and run-index insertion
+    // order share the log order), so one linear merge keeps flow order.
+    let nodes = out
+    if (this.commandIdx.size > 0) {
+      nodes = []
+      const commands = [...this.commandIdx.values()]
+      let next = 0
+      for (const node of out) {
+        for (let cmd = commands[next]; cmd !== undefined && cmd.seq < node.seq; cmd = commands[++next]) {
+          nodes.push(cmd)
+        }
+        nodes.push(node)
+      }
+      for (let cmd = commands[next]; cmd !== undefined; cmd = commands[++next]) nodes.push(cmd)
+    }
+    const value = { nodes, degraded: this.degraded }
     this.nodesResult = { rev: this.rev, value }
     return value
   }
@@ -193,6 +228,36 @@ export class FoldAdapter {
     return seqs
   }
 
+  /** Fold one command lifecycle event into its node (run mints, done settles in place; done-only soft-falls). */
+  private indexCommand(event: SessionEvent): void {
+    // Log-only plugin events: the host-side dsh-commands declaration cannot
+    // enter the client program, so this wire consumer narrows structurally
+    // (the same posture as tool/code-dispatch in session.ts).
+    if ((event.type as string) === 'command/run') {
+      const data = event.data as unknown as { commandId: CommandId; name: string; args: string }
+      this.commandIdx.set(data.commandId, {
+        kind: 'command', seq: event.seq, time: event.time,
+        commandId: data.commandId, name: data.name, args: data.args, outcome: null,
+      })
+      return
+    }
+    if ((event.type as string) !== 'command/done') return
+    const data = event.data as unknown as { commandId: CommandId; kind: 'success' | 'error'; text?: string }
+    const run = this.commandIdx.get(data.commandId)
+    const outcome = { kind: data.kind, ...data.text === undefined ? {} : { text: data.text } }
+    if (run === undefined) {
+      // Cross-window cut: the run page fell out of the window — build the
+      // node from the done alone (same soft-fall as a call-less tool result).
+      this.commandIdx.set(data.commandId, {
+        kind: 'command', seq: event.seq, time: event.time,
+        commandId: data.commandId, name: null, args: null, outcome,
+      })
+      return
+    }
+    // Settle in place: a fresh node object (published references stay immutable).
+    this.commandIdx.set(data.commandId, { ...run, outcome })
+  }
+
   private indexCall(event: SessionEvent, view?: ToolEventView): void {
     if (event.type === 'tool/result') {
       if (view?.for === 'result') this.resultViews.set(event.seq, view.view)

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

@@ -1,6 +1,6 @@
 // flattenLineage: summaries -> flat list with lineage indentation (pure function).
-// Roots sort by updatedAt desc, DFS expansion with children in the same order; orphaned lineage
-// degrades to root level; cycles fail soft and emit as roots.
+// The input order is authoritative; lineage only makes each child adjacent to its parent.
+// Orphaned lineage degrades to root level; cycles fail soft and emit as roots.
 
 import type { SessionId, SessionSummary } from '@deepseek-ai/dsh-client-connection/client'
 
@@ -15,6 +15,8 @@ export interface SessionListEntry {
   title?: string
   updatedAt: number
   running: boolean
+  /** Empty-log bit mirrored from the summary; lists hide blank sessions (filtering stays with the consumer). */
+  blank: boolean
   parentSessionId?: SessionId
   cwd?: string
   /** An approval question is pending on this session (mux-frame derived; the sidebar's amber dot). */
@@ -24,8 +26,9 @@ export interface SessionListEntry {
 }
 
 /**
- * summaries -> flat list with lineage indentation (pure; roots by updatedAt
- * desc, DFS children in the same order, orphans degrade to roots).
+ * Summaries -> flat list with lineage indentation. Root and sibling order
+ * follows the established input order; this projection never re-sorts a
+ * hydrated list from mutable timestamps.
  * @param summaries - the host's session.list items.
  * @param waitingApproval - sessions with a pending approval question (manager-owned live fact; absent = false).
  * @returns display rows in render order.
@@ -46,9 +49,6 @@ export function flattenLineage(summaries: readonly TitledSessionSummary[], waiti
     }
   }
 
-  const byUpdatedDesc = (a: TitledSessionSummary, b: TitledSessionSummary): number => b.updatedAt - a.updatedAt
-  roots.sort(byUpdatedDesc)
-
   const out: SessionListEntry[] = []
   const visited = new Set<SessionId>()
   const walk = (s: TitledSessionSummary, depth: number): void => {
@@ -60,7 +60,6 @@ export function flattenLineage(summaries: readonly TitledSessionSummary[], waiti
     out.push({ ...s, waitingApproval: waitingApproval?.has(s.sessionId) ?? false, depth })
     const kids = children.get(s.sessionId)
     if (kids === undefined) return
-    kids.sort(byUpdatedDesc)
     for (const kid of kids) walk(kid, depth + 1)
   }
   for (const root of roots) walk(root, 0)

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

@@ -2,31 +2,52 @@
 // dispatch entry + list state, constructed and held by SessionsService (one per client runtime).
 // List data never enters zustand; React connects via subscribe/getListSnapshot.
 
-import type { IApiClient, HostFrame, MuxFrame, RpcError, RpcRequest, RpcResult, SessionId, SessionSummary } from '@deepseek-ai/dsh-client-connection/client'
+import type { IApiClient, HostFrame, MuxFrame, RpcError, RpcRequest, RpcResult, SessionId, SessionSummary, WorkspaceId } from '@deepseek-ai/dsh-client-connection/client'
 // Value import from the inline-safe wire layer (not the connection plugin):
 // plugin-to-plugin value imports are a bundle purity error.
 import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
+import { mergeOrderedBaseline } from '../ordered-baseline.ts'
 import type { SessionListEntry, TitledSessionSummary } from './lineage.ts'
 import { flattenLineage } from './lineage.ts'
+// Type-only merge edge: the title domain's client-namespace outlet declares
+// the 'title' projection key this manager projects into list rows (and any
+// useProjection('title') consumer reads). Zero value imports by construction.
+import type {} from '@deepseek-ai/dsh-session-title/client'
 import { Notifier } from './notifier.ts'
+import { ProjectionValueStore } from './projection-store.ts'
 import { Session } from './session.ts'
 
+/**
+ * List arrival lifecycle, orthogonal to the pull-activity `state` axis:
+ * `pending` (no successful pull yet — an empty items array means "nothing
+ * arrived", not "nothing exists") → `ready` (at least one pull landed).
+ * Monotone: `ready` never steps back — later pull failures and reconnect
+ * re-pulls ride the `state`/`error` axis, which is where failure is modeled
+ * (no `error` phase here; that would duplicate `state`).
+ */
+export type SessionListPhase = 'pending' | 'ready'
+
 /** Immutable session-list snapshot for useSessionList. */
 export interface SessionListSnapshot {
   items: readonly SessionListEntry[]
+  /** Selected Session id (validated against items; masked to undefined while its session is off the list). */
+  current: SessionId | undefined
   state: 'idle' | 'loading' | 'error'
+  /** Arrival lifecycle (see {@link SessionListPhase}); `state` stays the pull-activity axis. */
+  phase: SessionListPhase
   error: RpcError | null
 }
 
+type SessionListMutation =
+  | { kind: 'upsert'; summary: SessionSummary }
+  | { kind: 'remove'; sessionId: SessionId }
+  | { kind: 'status'; sessionId: SessionId; running: boolean }
+  /** Local first-send flip: the sender clears blank without waiting for a host frame. */
+  | { kind: 'engaged'; sessionId: SessionId }
+
 /** Per-session cap for pre-instantiation approval/question buffering (low-frequency frames; a few dozen covers any real backlog). */
 const PENDING_BUFFER_CAP = 32
 
-/** Latest title control snapshot retained independently of list/instance arrival. */
-interface SessionTitleSnapshot {
-  title: string
-  eventSeq: number
-  updatedAt: number
-}
 
 /** Instance cluster + frame entry + the session list (see the web client architecture RFC). */
 export class SessionManager {
@@ -41,11 +62,21 @@ export class SessionManager {
    *  because the sidebar must light up for sessions never instantiated. Cleared per connection
    *  generation — the reopen replay re-adds still-pending questions — and on session-removed. */
   private readonly waitingApprovals = new Map<SessionId, Set<string>>()
-  private readonly titleSnapshots = new Map<SessionId, SessionTitleSnapshot>()
+  /** Per-session projection value stores, retained independently of instance arrival (the
+   *  title-snapshot precedent, generalized): push frames land here whether or not the Session
+   *  is instantiated (list rows read the 'title' key), and an instantiated Session adopts the
+   *  same store so history-baseline seeding and frames converge on one row set. */
+  private readonly projectionStores = new Map<SessionId, ProjectionValueStore>()
   private summaries: SessionSummary[] = []
   private listState: 'idle' | 'loading' | 'error' = 'idle'
+  /** Arrival phase; the pending → ready edge fires on the first successful pull (see SessionListPhase). */
+  private listPhase: SessionListPhase = 'pending'
   private listError: RpcError | null = null
   private listInflight: Promise<void> | null = null
+  /** Mutations arriving after a list request starts are replayed over its response. */
+  private listMutations: SessionListMutation[] | null = null
+
+  private selected: SessionId | undefined
 
   private listSnapshotCache: SessionListSnapshot
   /** Entry-identity cache (§C.2 reference stability): list rebuilds reuse the previous entry
@@ -57,12 +88,50 @@ export class SessionManager {
     this.listSnapshotCache = this.buildListSnapshot()
   })
 
-  constructor(private readonly api: IApiClient) {
+  /**
+   * @param api - shared wire client.
+   * @param restoredSelection - persisted real-Session selection candidate.
+   */
+  constructor(
+    private readonly api: IApiClient,
+    restoredSelection?: SessionId,
+  ) {
+    this.selected = restoredSelection
     this.listSnapshotCache = this.buildListSnapshot()
   }
 
+  // ---- Selection ----
+
+  /**
+   * Select a listed Session.
+   * @param sessionId - listed Session id.
+   */
+  select(sessionId: SessionId): void {
+    if (!this.summaries.some(summary => summary.sessionId === sessionId)) {
+      throw new Error(`sessions.select: unknown session ${sessionId}`)
+    }
+    this.selected = sessionId
+    this.notifier.notifyNow()
+  }
+
+  /** Clear the selection (the layout falls to the no-session view state). */
+  clearSelection(): void {
+    this.selected = undefined
+    this.notifier.notifyNow()
+  }
+
   // ---- Instance management ----
 
+  /**
+   * Drop a session instance (scope-prune companion, decision 12: instance
+   * and scope share one lifecycle). The host session log is the durable
+   * truth — a later get() lazily rebuilds and open() backfills history.
+   * @param sessionId - the session to drop.
+   */
+  drop(sessionId: SessionId): void {
+    this.sessions.delete(sessionId)
+  }
+
   /**
    * Lazy build: return the existing instance or construct one (no auto-open —
    * open is triggered by the container's select callback).
@@ -72,21 +141,53 @@ export class SessionManager {
   get(sessionId: SessionId): Session {
     let session = this.sessions.get(sessionId)
     if (session === undefined) {
-      session = new Session(sessionId, this.api)
+      session = this.createSession(sessionId)
       this.sessions.set(sessionId, session)
-      // Sync the running bit from the list snapshot into the new instance (consistency when the list precedes open).
-      const summary = this.summaries.find(s => s.sessionId === sessionId)
-      if (summary !== undefined) session.handleRunning(summary.running)
-      // Replay approval/question frames buffered before instantiation (rpcId verbatim, same semantics as the subscribed baseline replay).
+      // Replay approval/question/queued frames buffered before instantiation (rpcId
+      // verbatim, same semantics as the subscribed baseline replay). Replay happens
+      // BEFORE the running-bit sync: a not-running summary must sweep replayed queue
+      // rows the same way a live status flip would (their retirement events dropped
+      // while the session was uninstantiated).
       const buffered = this.pendingBuffers.get(sessionId)
       if (buffered !== undefined) {
         this.pendingBuffers.delete(sessionId)
         for (const envelope of buffered) session.handleMuxEnvelope(envelope.rpcId, envelope.payload)
       }
+      // Sync the running and blank bits from the list snapshot into the new
+      // instance (consistency when the list precedes open).
+      const summary = this.summaries.find(s => s.sessionId === sessionId)
+      if (summary !== undefined) {
+        session.handleBlank(summary.blank)
+        session.handleRunning(summary.running)
+      }
     }
     return session
   }
 
+  private createSession(sessionId: SessionId): Session {
+    return new Session(sessionId, this.api, {
+      // The sender's local first-send flip mirrors into the list row so the
+      // session surfaces (lists filter on blank) before any host frame lands.
+      onEngaged: (engaged) => {
+        this.recordMutation({ kind: 'engaged', sessionId: engaged.sessionId })
+      },
+      projections: this.projectionStore(sessionId),
+    })
+  }
+
+  /** Resident per-session projection store (create-on-demand; outlives instantiation). */
+  private projectionStore(sessionId: SessionId): ProjectionValueStore {
+    let store = this.projectionStores.get(sessionId)
+    if (store === undefined) {
+      store = new ProjectionValueStore()
+      // List rows project off store keys (title); any-key changes re-enter
+      // the manager's own batched rebuild channel.
+      store.subscribeAny(() => { this.notifier.markDirty() })
+      this.projectionStores.set(sessionId, store)
+    }
+    return store
+  }
+
   // ---- List surface ----
 
   /** Full refresh via session.list (single-flight: an in-flight call is reused). */
@@ -94,15 +195,28 @@ export class SessionManager {
     if (this.listInflight !== null) return this.listInflight
     this.listState = 'loading'
     this.listError = null
+    const established = this.summaries
+    const mutations: SessionListMutation[] = []
+    this.listMutations = mutations
     this.notifier.markDirty()
     this.listInflight = (async () => {
       try {
         const { result } = await this.api.sessions.list({})
         if (result.ok) {
-          this.summaries = result.value.items
+          let summaries = this.listPhase === 'pending'
+            ? result.value.items
+            : mergeOrderedBaseline(established, result.value.items, summary => summary.sessionId)
+          for (const mutation of mutations) summaries = applyMutation(summaries, mutation)
+          this.summaries = summaries
           this.listState = 'idle'
-          // Push running bits down to instantiated Sessions (the list is the authoritative summary source).
-          for (const s of this.summaries) this.sessions.get(s.sessionId)?.handleRunning(s.running)
+          this.listPhase = 'ready'
+          // Push running/blank bits down to instantiated Sessions (the list is the authoritative summary source).
+          for (const s of this.summaries) {
+            const session = this.sessions.get(s.sessionId)
+            if (session === undefined) continue
+            session.handleBlank(s.blank)
+            session.handleRunning(s.running)
+          }
         } else {
           this.listState = 'error'
           this.listError = result.error
@@ -113,6 +227,7 @@ export class SessionManager {
         /* v8 ignore next -- the `? null` arm is unreachable: transportError always returns ok:false. */
         this.listError = folded.ok ? null : folded.error
       } finally {
+        this.listMutations = null
         this.listInflight = null
         this.notifier.markDirty()
       }
@@ -122,19 +237,38 @@ export class SessionManager {
 
   /**
    * Contract session.create; on success merge into summaries immediately (no
-   * wait for the next refresh).
-   * @param cwd - optional working directory for the new session.
+   * wait for the next refresh). A created session is blank by definition
+   * (entity birth precedes the first message).
+   * @param opts - target workspace or working directory, plus an optional caller-owned id.
    * @returns the create result.
    */
-  async create(cwd?: string): Promise<RpcResult<{ sessionId: SessionId }>> {
+  async create(
+    opts: { workspaceId?: WorkspaceId; cwd?: string; sessionId?: SessionId } = {},
+  ): Promise<RpcResult<{ sessionId: SessionId }>> {
     try {
-      const { result } = await this.api.sessions.create(cwd === undefined ? {} : { cwd })
-      if (result.ok && !this.summaries.some(s => s.sessionId === result.value.sessionId)) {
-        this.summaries = [
-          { sessionId: result.value.sessionId, updatedAt: Date.now(), running: false, ...(cwd !== undefined ? { cwd } : {}) },
-          ...this.summaries,
-        ]
-        this.notifier.markDirty()
+      const shared = opts.sessionId === undefined ? {} : { sessionId: opts.sessionId }
+      const payload = opts.workspaceId !== undefined
+        ? { workspaceId: opts.workspaceId, ...shared }
+        : { ...(opts.cwd === undefined ? {} : { cwd: opts.cwd }), ...shared }
+      const { result } = await this.api.sessions.create(payload)
+      if (result.ok) {
+        this.recordMutation({ kind: 'upsert', summary: {
+          sessionId: result.value.sessionId, updatedAt: Date.now(), running: false, blank: true,
+          ...(opts.cwd !== undefined ? { cwd: opts.cwd } : {}),
+        } })
+      } else {
+        const publishedSessionId = workspaceAttachSessionId(result.error)
+        // Publication precedes attachment. The error's id is a real Session,
+        // so expose it immediately as Ungrouped while the caller keeps the
+        // prompt buffer and decides whether to retry attachment.
+        if (publishedSessionId !== undefined) {
+          this.recordMutation({ kind: 'upsert', summary: {
+            sessionId: publishedSessionId,
+            updatedAt: Date.now(),
+            running: false,
+            blank: true,
+          } })
+        }
       }
       return result
     } catch (error) {
@@ -142,6 +276,23 @@ export class SessionManager {
     }
   }
 
+  /**
+   * Insert-or-enrich a locally synthesized summary: a new id prepends; an
+   * existing entry only gains fields it lacks (the session-added frame and the
+   * create() echo race — whichever lands second must fill the placeholder's
+   * missing cwd/parentSessionId, never overwrite list-refresh data).
+   */
+  private mergeSummary(summary: SessionSummary): void {
+    this.recordMutation({ kind: 'upsert', summary })
+  }
+
+  /** Apply immediately and retain for replay when a list response is in flight. */
+  private recordMutation(mutation: SessionListMutation): void {
+    this.listMutations?.push(mutation)
+    this.summaries = applyMutation(this.summaries, mutation)
+    this.notifier.markDirty()
+  }
+
   // ---- Subscription surface (for useSessionList) ----
 
   /**
@@ -173,22 +324,32 @@ export class SessionManager {
   handleMuxEnvelope(envelope: RpcRequest<MuxFrame>): void {
     const frame = envelope.payload
     if (frame.type === 'stream/error') return // Controller already treats this as stream failure
-    if (frame.type === 'session/title') {
-      const current = this.titleSnapshots.get(frame.sessionId)
-      if (current !== undefined && current.eventSeq >= frame.eventSeq) return
-      this.titleSnapshots.set(frame.sessionId, {
-        title: frame.title,
-        eventSeq: frame.eventSeq,
-        updatedAt: frame.updatedAt,
-      })
+    if (frame.type === 'session/projection') {
+      // Finished host-computed value: land it in the resident store whether or
+      // not the Session is instantiated (list rows read the 'title' key). The
+      // synchronous markDirty keeps the list snapshot same-tick fresh (the
+      // store's own any-key channel is microtask-batched).
+      this.projectionStore(frame.sessionId).apply(frame.key, frame.value, frame.seq)
       this.notifier.markDirty()
       return
     }
     if (frame.type === 'session/subscribed') {
-      const current = this.titleSnapshots.get(frame.sessionId)
-      if (current !== undefined && current.eventSeq > frame.lastSeq) {
-        this.titleSnapshots.delete(frame.sessionId)
-        this.notifier.markDirty()
+      // Rows past the host's durable baseline rode state a restart lost; drop
+      // them so last-wins cannot pin a phantom value over recomputed truth.
+      this.projectionStores.get(frame.sessionId)?.truncate(frame.lastSeq)
+      this.notifier.markDirty()
+      // New mux-generation baseline: buffered session/queued frames belong to
+      // the previous generation and the host is about to resend the live
+      // snapshot — drop them, or every reconnect appends a duplicate batch
+      // (and enough reconnects push real approval/question frames past the
+      // cap). Same re-baseline signal Session uses for its own mirror.
+      const buffered = this.pendingBuffers.get(frame.sessionId)
+      if (buffered !== undefined) {
+        const kept = buffered.filter(item => item.payload.type !== 'session/queued')
+        if (kept.length !== buffered.length) {
+          if (kept.length === 0) this.pendingBuffers.delete(frame.sessionId)
+          else this.pendingBuffers.set(frame.sessionId, kept)
+        }
       }
     }
     // List-level waiting-approval bit (the sidebar amber dot): tracked here for
@@ -209,13 +370,15 @@ export class SessionManager {
     }
     const session = this.sessions.get(frame.sessionId)
     if (session === undefined) {
-      // Approval/question frames never hit history: buffer for replay on instantiation;
-      // everything else drops (not instantiated — history fully backfills on open).
+      // Approval/question/queued frames never hit history: buffer for replay on
+      // instantiation; everything else drops (not instantiated — history fully
+      // backfills on open).
       switch (frame.type) {
         case 'approval/requested':
         case 'approval/resolved':
         case 'question/requested':
-        case 'question/resolved': {
+        case 'question/resolved':
+        case 'session/queued': {
           const buffer = this.pendingBuffers.get(frame.sessionId) ?? []
           buffer.push(envelope)
           if (buffer.length > PENDING_BUFFER_CAP) buffer.splice(0, buffer.length - PENDING_BUFFER_CAP)
@@ -237,32 +400,25 @@ export class SessionManager {
     const frame = envelope.payload
     switch (frame.type) {
       case 'host/session-added': {
-        if (!this.summaries.some(s => s.sessionId === frame.sessionId)) {
-          this.summaries = [
-            {
-              sessionId: frame.sessionId, updatedAt: Date.now(), running: false,
-              ...(frame.parentSessionId !== undefined ? { parentSessionId: frame.parentSessionId } : {}),
-            },
-            ...this.summaries,
-          ]
-          this.notifier.markDirty()
-        }
+        this.mergeSummary({
+          sessionId: frame.sessionId, updatedAt: Date.now(), running: false, blank: frame.blank,
+          ...(frame.parentSessionId !== undefined ? { parentSessionId: frame.parentSessionId } : {}),
+          ...(frame.cwd !== undefined ? { cwd: frame.cwd } : {}),
+        })
+        this.sessions.get(frame.sessionId)?.handleBlank(frame.blank)
         return
       }
       case 'host/session-removed': {
-        this.summaries = this.summaries.filter(s => s.sessionId !== frame.sessionId)
+        this.recordMutation({ kind: 'remove', sessionId: frame.sessionId })
         this.sessions.get(frame.sessionId)?.handleRemoved() // instance survives (resident-instance rule), only flagged in the snapshot
         this.pendingBuffers.delete(frame.sessionId) // a removed session's buffered frames must not replay on a future instantiation
         this.waitingApprovals.delete(frame.sessionId) // a removed session cannot wait on anyone
-        this.titleSnapshots.delete(frame.sessionId)
-        this.notifier.markDirty()
+        this.projectionStores.delete(frame.sessionId) // removed sessions drop their projection rows with the instance
         return
       }
       case 'host/session-status': {
-        this.summaries = this.summaries.map(s =>
-          s.sessionId === frame.sessionId && s.running !== frame.running ? { ...s, running: frame.running } : s)
+        this.recordMutation({ kind: 'status', sessionId: frame.sessionId, running: frame.running })
         this.sessions.get(frame.sessionId)?.handleRunning(frame.running)
-        this.notifier.markDirty()
         return
       }
       case 'host/agent-error': {
@@ -274,7 +430,7 @@ export class SessionManager {
     }
   }
 
-  /** After each connection generation (first connect included): refresh the list + resync opened instances (reconnect = rebuild). */
+  /** After each connection generation: refresh the session baseline and rebuild opened windows. */
   handleConnected(): void {
     // Approvals resolved while disconnected send no frame: drop the bits and
     // let the mux-open replay re-add every still-pending question.
@@ -288,16 +444,19 @@ export class SessionManager {
 
   private buildListSnapshot(): SessionListSnapshot {
     const merged: TitledSessionSummary[] = this.summaries.map((summary) => {
-      const title = this.titleSnapshots.get(summary.sessionId)
-      return title === undefined
-        ? summary
-        : { ...summary, title: title.title, updatedAt: Math.max(summary.updatedAt, title.updatedAt) }
+      // List rows read the generic 'title' projection key (host-computed unit
+      // value; the bespoke session/title frame is retired).
+      const title = this.projectionStores.get(summary.sessionId)?.get('title')
+      return typeof title === 'string' && title !== ''
+        ? { ...summary, title }
+        : summary
     })
     const fresh = flattenLineage(merged, new Set(this.waitingApprovals.keys()))
     const items = fresh.map((entry) => {
       const prev = this.entryCache.get(entry.sessionId)
       if (
         prev !== undefined && prev.updatedAt === entry.updatedAt && prev.running === entry.running
+        && prev.blank === entry.blank
         && prev.parentSessionId === entry.parentSessionId && prev.cwd === entry.cwd
         && prev.title === entry.title && prev.depth === entry.depth
         && prev.waitingApproval === entry.waitingApproval
@@ -310,6 +469,57 @@ export class SessionManager {
     }
     const sameOrder = items.length === this.itemsCache.length && items.every((e, i) => e === this.itemsCache[i])
     if (!sameOrder) this.itemsCache = items
-    return { items: this.itemsCache, state: this.listState, error: this.listError }
+    const selected = this.selected
+    const current = selected !== undefined && items.some(item => item.sessionId === selected)
+      ? selected
+      : undefined
+    return {
+      items: this.itemsCache,
+      current,
+      state: this.listState,
+      phase: this.listPhase,
+      error: this.listError,
+    }
   }
 }
+
+/** Apply one list mutation without deriving display order. */
+function applyMutation(summaries: readonly SessionSummary[], mutation: SessionListMutation): SessionSummary[] {
+  switch (mutation.kind) {
+    case 'upsert': {
+      const existing = summaries.find(summary => summary.sessionId === mutation.summary.sessionId)
+      if (existing === undefined) return [mutation.summary, ...summaries]
+      const filled: SessionSummary = {
+        ...existing,
+        // Blank only lowers: a stale true (session-added racing the local
+        // first send) never re-hides an already-surfaced session.
+        blank: existing.blank && mutation.summary.blank,
+        ...(existing.cwd === undefined && mutation.summary.cwd !== undefined ? { cwd: mutation.summary.cwd } : {}),
+        ...(existing.parentSessionId === undefined && mutation.summary.parentSessionId !== undefined
+          ? { parentSessionId: mutation.summary.parentSessionId } : {}),
+      }
+      if (filled.cwd === existing.cwd && filled.parentSessionId === existing.parentSessionId
+        && filled.blank === existing.blank) return [...summaries]
+      return summaries.map(summary => summary.sessionId === mutation.summary.sessionId ? filled : summary)
+    }
+    case 'remove':
+      return summaries.filter(summary => summary.sessionId !== mutation.sessionId)
+    case 'status':
+      // running:true doubles as the cross-端 blank flip (a blank session
+      // never runs, so the first running frame proves a message landed).
+      return summaries.map(summary => summary.sessionId === mutation.sessionId
+        && (summary.running !== mutation.running || (mutation.running && summary.blank))
+        ? { ...summary, running: mutation.running, blank: summary.blank && !mutation.running }
+        : summary)
+    case 'engaged':
+      return summaries.map(summary => summary.sessionId === mutation.sessionId && summary.blank
+        ? { ...summary, blank: false }
+        : summary)
+  }
+}
+
+/** Temporary source-plane bridge while the Host contract and client project build independently. */
+function workspaceAttachSessionId(error: RpcError): SessionId | undefined {
+  const candidate = error as unknown as { code: string; details: { sessionId?: SessionId } }
+  return candidate.code === 'workspace-attach-failed' ? candidate.details.sessionId : undefined
+}

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

@@ -3,11 +3,17 @@
 // the flush rebuilds the snapshot cache BEFORE notifying (useSyncExternalStore requires a stable
 // getSnapshot reference). With no listeners the rebuild is skipped and only the dirty bit is set
 // (keeps frame storms cheap); the next getSnapshot rebuilds lazily.
+//
+// Freshness and notification are SEPARATE bits: a pull (ensureFresh) between
+// markDirty and the scheduled flush rebuilds the snapshot but must not
+// swallow the notification — push subscribers (object-layer watchers) would
+// otherwise starve whenever any reader pulls first.
 
 /** Subscription + microtask-batched notification primitive (shared by Session and SessionManager). */
 export class Notifier {
   private listeners = new Set<() => void>()
   private dirty = false
+  private notifyPending = false
   private scheduled = false
 
   /** @param rebuild - snapshot rebuild function injected by the owner (writes the owner's snapshotCache). */
@@ -28,14 +34,18 @@ export class Notifier {
   /** State-change entry: mark dirty and schedule the batched flush. */
   markDirty(): void {
     this.dirty = true
+    this.notifyPending = true
     if (this.scheduled) return
     this.scheduled = true
     queueMicrotask(() => {
       this.scheduled = false
-      if (!this.dirty) return
-      if (this.listeners.size === 0) return // lazy: no subscribers, keep dirty for the next getSnapshot
-      this.dirty = false
-      this.rebuild()
+      if (!this.notifyPending) return
+      if (this.listeners.size === 0) return // lazy: no subscribers; dirty (if still set) rebuilds on next getSnapshot
+      this.notifyPending = false
+      if (this.dirty) {
+        this.dirty = false
+        this.rebuild()
+      }
       for (const listener of this.listeners) listener()
     })
   }
@@ -46,13 +56,18 @@ export class Notifier {
    */
   notifyNow(): void {
     this.dirty = true
+    this.notifyPending = true
     if (this.listeners.size === 0) return // lazy: same as markDirty, next getSnapshot rebuilds
+    this.notifyPending = false
     this.dirty = false
     this.rebuild()
     for (const listener of this.listeners) listener()
   }
 
-  /** Pre-getSnapshot check: rebuild synchronously when dirty (read path before first subscribe / while unobserved). */
+  /**
+   * Pre-getSnapshot check: rebuild synchronously when dirty (read path
+   * before first subscribe / while unobserved). Notification stays pending.
+   */
   ensureFresh(): void {
     if (!this.dirty) return
     this.dirty = false

packages/client/runtime/src/client/sessions/projection-store.ts

@@ -0,0 +1,183 @@
+/**
+ * Generic per-session projection value store (session-projection RFC, push
+ * model): the host is the only computation site; the client holds finished
+ * whole values per key — `key → { value, seq }` — seeded by the history tail
+ * page's projections block and updated by `session/projection` push frames,
+ * under the single rule **higher seq wins**. No client-side domain folding
+ * exists: a domain ships projection support with zero client code. Per-key
+ * bare observable faces feed `useProjection` (web-react binds them).
+ */
+import type { SessionProjectionMap } from '@deepseek-ai/dsh-session-projection/types'
+import type { ObservableSnapshot } from '../contract/store.ts'
+import { Notifier } from './notifier.ts'
+
+// The single projection type table, typed end to end (host unit, wire block,
+// client store, React hook) — the interface package's pure-type outlet
+// (`/types`, zero imports), never the package root: the root's dsh-agent →
+// dsh-session chain would drag the host `Context.sessions` merge into the
+// client program (one program must not hold both sides). No second
+// client-side "views" table (user ruling, RFC Alternatives).
+export type { SessionProjectionMap } from '@deepseek-ai/dsh-session-projection/types'
+
+/**
+ * The fifth framework hook seat (session-projection RFC): key-addressed
+ * projection reader delivered through the standard kit. `undefined` uniformly
+ * means capability absent — host unit unmounted, or no baseline/frame has
+ * carried the key yet. The selector overload mirrors useSession (per-key uSES
+ * binding; reference stability holds because a key's value reference changes
+ * only when a frame or baseline lands).
+ */
+export type UseProjection = {
+  <K extends Extract<keyof SessionProjectionMap, string>>(key: K): SessionProjectionMap[K] | undefined
+  <K extends Extract<keyof SessionProjectionMap, string>, S>(
+    key: K,
+    selector: (value: SessionProjectionMap[K] | undefined) => S,
+    eq?: (a: S, b: S) => boolean,
+  ): S
+}
+
+/**
+ * Tail-page projections baseline — structurally identical to the wire's
+ * `SessionProjectionsBlock` (apiproxy api layer), restated here so the
+ * React-free store depends only on the type table, not the wire package's
+ * response vocabulary.
+ */
+export interface ProjectionsBaseline {
+  /** The consistent-cut seq (equals the window tail seq by construction). */
+  asOfSeq: number
+  /** Whole current values by key; a registered key absent here means the capability is absent. */
+  values: Partial<SessionProjectionMap>
+}
+
+/** One key's row: the latest finished value and the seq it is consistent with. */
+interface Row {
+  value: unknown
+  seq: number
+}
+
+/** Per-key notification channel: the bare face plus its batching notifier. */
+interface Channel {
+  face: ObservableSnapshot<unknown>
+  notifier: Notifier
+}
+
+/**
+ * One session's projection values. Framework semantics, uniform across every
+ * key: a baseline seeds rows at its cut, a push frame updates one row, and in
+ * both paths a lower-or-equal seq loses — a replayed frame cannot regress a
+ * value, a stale baseline cannot overwrite a newer frame. A key the store has
+ * never seen reads `undefined` (capability absent). Faces are identity-stable
+ * per key (create-on-demand, cached) so the React side binds each exactly
+ * once; the store-level channel (`subscribeAny`) serves coarse consumers (the
+ * manager's list projection reads the `title` key).
+ */
+export class ProjectionValueStore {
+  private readonly rows = new Map<string, Row>()
+  private readonly channels = new Map<string, Channel>()
+  /** Coarse any-key channel (no snapshot cache to rebuild: reads hit rows directly). */
+  private readonly anyNotifier = new Notifier(() => {})
+
+  /**
+   * Key-addressed bare observable face (the useProjection resolution path).
+   * Always defined — absence is an `undefined` snapshot, never a missing
+   * face, so a component may subscribe before the key ever carries a value.
+   * @param key - projection key.
+   * @returns the identity-stable face for this key.
+   */
+  faceOf(key: string): ObservableSnapshot<unknown> {
+    return this.channel(key).face
+  }
+
+  /**
+   * Current whole value for a key (erased framework read; typed reads go
+   * through `useProjection`'s map lookup).
+   * @param key - projection key.
+   * @returns the value, or undefined while the key is absent.
+   */
+  get(key: string): unknown {
+    return this.rows.get(key)?.value
+  }
+
+  /**
+   * Subscribe to any-key changes (microtask-batched) — the manager's list
+   * rebuild channel.
+   * @param listener - change callback.
+   * @returns the unsubscribe function.
+   */
+  subscribeAny(listener: () => void): () => void {
+    return this.anyNotifier.subscribe(listener)
+  }
+
+  /**
+   * Apply one finished value (the `session/projection` push-frame path).
+   * @param key - projection key.
+   * @param value - whole value computed by the host unit.
+   * @param seq - the unit's watermark at emission.
+   */
+  apply(key: string, value: unknown, seq: number): void {
+    const row = this.rows.get(key)
+    if (row !== undefined && seq <= row.seq) return // higher seq wins; replays and stale frames drop
+    this.rows.set(key, { value, seq })
+    this.changed(key)
+  }
+
+  /**
+   * Seed from a history tail page's projections block: every carried key
+   * lands under the same seq rule as frames; a key the block omits is
+   * capability-absent as of the cut — its row clears unless a newer frame
+   * already superseded the cut (a stale baseline can neither overwrite nor
+   * clear newer values).
+   * @param baseline - the response's projections block.
+   */
+  seed(baseline: ProjectionsBaseline): void {
+    // Erased walk: the framework crosses the open key space; per-key typing
+    // is re-established at the consumer (useProjection's map lookup).
+    const values = baseline.values as Record<string, unknown>
+    for (const key of Object.keys(values)) this.apply(key, values[key], baseline.asOfSeq)
+    for (const [key, row] of this.rows) {
+      if (Object.hasOwn(values, key)) continue
+      if (row.seq > baseline.asOfSeq) continue
+      this.rows.delete(key)
+      this.changed(key)
+    }
+  }
+
+  /**
+   * Drop rows past a mux-generation baseline (`session/subscribed.lastSeq`):
+   * a row claiming knowledge beyond the host's own durable baseline rode
+   * state a restart lost — under last-wins it would wrongly outrank the
+   * host's recomputed (lower-seq) values forever. Durable replay and the next
+   * baseline re-seed whatever truly survived (the title-snapshot precedent,
+   * generalized).
+   * @param lastSeq - the subscribed frame's durable baseline seq.
+   */
+  truncate(lastSeq: number): void {
+    for (const [key, row] of this.rows) {
+      if (row.seq <= lastSeq) continue
+      this.rows.delete(key)
+      this.changed(key)
+    }
+  }
+
+  private changed(key: string): void {
+    this.channels.get(key)?.notifier.markDirty()
+    this.anyNotifier.markDirty()
+  }
+
+  private channel(key: string): Channel {
+    let channel = this.channels.get(key)
+    if (channel === undefined) {
+      // The notifier only batches (no snapshot cache to rebuild: faces read rows directly).
+      const notifier = new Notifier(() => {})
+      channel = {
+        notifier,
+        face: {
+          getSnapshot: () => this.rows.get(key)?.value,
+          subscribe: listener => notifier.subscribe(listener),
+        },
+      }
+      this.channels.set(key, channel)
+    }
+    return channel
+  }
+}

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

@@ -2,8 +2,9 @@
  * SessionsService: root sessions service — list snapshot store (manager
  * projection; carries `current`, the persisted selection every
  * session-scoped surface keys off — migrated here from ui-layout per the
- * slot-parity design), session scope tree (mintScope pattern: no-op plugin
- * Fiber + ctx.extend scope tag), stable SessionBinding cache, ancestry walk.
+ * slot-parity design), Agent scope tree (mintScope pattern: no-op plugin
+ * Fiber + ctx.extend scope tag; one scope per session, agent id === session
+ * id), stable SessionBinding cache, ancestry walk.
  *
  * Scope lifecycle is stage-driven: a scope is minted lazily on first
  * resolution (pure — resolution has no side effects and is render-safe);
@@ -15,11 +16,15 @@
  * 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'
-import type { SessionCell } from '@deepseek-ai/dsh-client-ui-slots'
+import type { IApiClient, RpcError, SessionId, WorkspaceId } from '@deepseek-ai/dsh-client-connection/client'
+import type {
+  HostObservable, SessionMaybeProvideInfo, SessionProvideInfo,
+} from '@deepseek-ai/dsh-client-ui-slots'
 import type { SnapshotStore } from '../contract/store.ts'
 import { createSnapshotStore } from '../contract/store.ts'
+import { createScope, scopeOf as scopeTagOf } from '../agents/scope.ts'
 import { SessionManager } from './manager.ts'
+import type { SessionListPhase } from './manager.ts'
 import type { Session } from './session.ts'
 
 /** Session list row projected from the host list RPC plus live stream increments. */
@@ -34,6 +39,13 @@ export interface SessionSummary {
   running: boolean
   /** An approval question is pending on this session (sidebar amber-dot state). */
   waitingApproval: boolean
+  /**
+   * Empty-log bit (host summary derivation mirror). New Session reuses a blank
+   * one targeting the same workspace. Filtering stays with the consumer: the
+   * store carries every row, while the Workspace browser shows only the
+   * selected blank entry.
+   */
+  blank: boolean
   updatedAt: number
 }
 
@@ -42,7 +54,29 @@ export interface SessionSummary {
  * the single useSessions standard hook reads list and selection together —
  * sidebar highlighting and SessionProvider share one fact source).
  */
-export interface SessionListState { ids: SessionId[]; byId: Record<SessionId, SessionSummary>; current: SessionId | undefined }
+export interface SessionListState {
+  ids: SessionId[]
+  byId: Record<SessionId, SessionSummary>
+  current: SessionId | undefined
+  /** Arrival lifecycle projected 1:1 from the manager snapshot (see SessionListPhase): empty-with-ready means "truly no sessions". */
+  phase: SessionListPhase
+}
+
+/** Structured session-create failure. */
+export class SessionCreateError extends Error {
+  override readonly name = 'SessionCreateError'
+
+  /**
+   * @param rpcError - Host business or folded transport error.
+   * @param requestedSessionId - caller-preallocated id used for later stream/list reconciliation.
+   */
+  constructor(
+    readonly rpcError: RpcError,
+    readonly requestedSessionId: SessionId | undefined,
+  ) {
+    super(`session create failed: ${rpcError.code}: ${rpcError.message}`)
+  }
+}
 
 /** Session assembly handle for SessionProvider/inject factories (identity-stable per session). */
 export interface SessionBinding {
@@ -51,21 +85,25 @@ export interface SessionBinding {
   readonly ctx: Context
 }
 
-/** Scope tag key (client counterpart of the host dsh-scope pattern). */
-const kScope = Symbol('dsh.client.scope')
+// Scope primitives live in ../agents/scope.ts (the client mirror of host
+// dsh-scope, keyed by Agent identity); re-exported here so existing
+// consumers keep their import site.
+export { scopeOf } from '../agents/scope.ts'
 
 /**
- * Read the session scope tag off a context.
- * @param ctx - any client context.
- * @returns the session id, or undefined on root contexts.
+ * Workspace display title of a session cwd: the path's last non-empty
+ * segment (both separators accepted; trailing separators ignored), or ''
+ * for separator-only paths — callers own their fallback (session id, raw
+ * cwd, default-directory copy). The repo-wide single basename derivation —
+ * every surface naming a workspace (picker rows, toggle labels, list titles)
+ * calls this instead of re-splitting paths.
+ * @param cwd - workspace directory path.
+ * @returns basename title, or '' when no non-empty segment exists.
  */
-export function scopeOf(ctx: Context): SessionId | undefined {
-  return (ctx as Context & { [kScope]?: SessionId })[kScope]
+export function workspaceTitleOf(cwd: string): string {
+  return cwd.replace(/[/\\]+$/, '').split(/[/\\]/).pop() ?? ''
 }
 
-/** Shared no-op plugin backing each session scope fiber. */
-function sessionScope(): void {}
-
 /**
  * Display title projection: durable title, project directory basename, then
  * the raw id.
@@ -73,8 +111,8 @@ function sessionScope(): void {}
 function displayTitleOf(title: string | undefined, cwd: string | undefined, id: SessionId): string {
   if (title !== undefined) return title
   if (cwd !== undefined && cwd !== '') {
-    const base = cwd.replace(/[/\\]+$/, '').split(/[/\\]/).pop()
-    if (base !== undefined && base !== '') return base
+    const base = workspaceTitleOf(cwd)
+    if (base !== '') return base
   }
   return id
 }
@@ -83,16 +121,45 @@ interface ScopeRecord {
   fiber: Fiber
   ctx: Context
   binding: SessionBinding
-  /** Render-layer standard kit (identity-stable per scope; the renderer's per-cell caches key off it). */
-  cell: SessionCell
+  /** Render-layer standard-props bundle (identity-stable per scope; the renderer's per-info caches key off it). */
+  provideInfo: SessionProvideInfo
+}
+
+/** One plugin's per-session standard-props contribution (see {@link SessionsService.provide}). */
+export interface SessionProvideContribution {
+  /** Bare observable sources, keyed by hook base name ('input' → useInput). */
+  hooks?: Record<string, HostObservable<unknown>>
+  /** Stable plain members (action callbacks etc.), spread into standard props verbatim. */
+  props?: Record<string, unknown>
+}
+
+/**
+ * Static declaration plus per-session resolver for one standard-kit
+ * contribution. The declared names let the renderer construct the same hook
+ * and prop surface while no session is current.
+ */
+export interface SessionProvideDescriptor {
+  /** Hook base names (`input` becomes `useInput`). */
+  hooks?: readonly string[]
+  /** Plain standard-prop names. */
+  props?: readonly string[]
+  /** Resolve every declared member for one definite session. */
+  resolve(binding: SessionBinding): SessionProvideContribution
 }
 
 /** Root sessions service: list store, current selection, object-layer manager, scope tree, bindings, ancestry. */
 export class SessionsService {
   /** List snapshot store (list RPC + host stream increments; re-pulled on reconnect) — the useSessions standard feed, current included. */
   readonly list: SnapshotStore<SessionListState>
-  /** The object-layer instance cluster and frame dispatch entry (wired to the connection by the runtime apply). */
-  readonly manager: SessionManager
+  /** The object-layer instance cluster and frame dispatch entry. */
+  private readonly manager: SessionManager
+  /**
+   * Atomic current-session provide projection: selection changes and
+   * provider-roster changes publish through this one source (the renderer
+   * host's `sessions.provide` feed), so a roster change under a stable
+   * current id republishes the bundle instead of stranding mounted entries.
+   */
+  readonly currentProvideInfo: HostObservable<SessionMaybeProvideInfo>
 
   /**
    * Persisted selection cell (the durable half of `list.current`). Private on
@@ -105,6 +172,14 @@ export class SessionsService {
   private readonly selection: SnapshotStore<{ sessionId?: SessionId }>
 
   private readonly scopes = new Map<SessionId, ScopeRecord>()
+  /** Registered per-session standard-props providers, in registration order. */
+  private readonly providers: SessionProvideDescriptor[] = []
+  /** Static no-session projection, rebuilt only when the provider roster changes. */
+  private maybeInfo: SessionMaybeProvideInfo
+  /** Latest published {@link SessionsService.currentProvideInfo} bundle (identity comparison dedupes republish). */
+  private currentProvideInfoSnapshot: SessionMaybeProvideInfo
+  /** currentProvideInfo subscribers (plain cell: bundles hold live Session sources, so no store freeze may touch them). */
+  private readonly currentProvideInfoListeners = new Set<() => void>()
   /**
    * The staged session id — follows `list.current` exactly, holding its last
    * defined value across masked gaps (a transiently absent selection blanks
@@ -119,12 +194,14 @@ export class SessionsService {
    * @param ctx - client root context (scope fibers mount under it).
    * @param api - wire client shared with every Session.
    */
-  constructor(private readonly rootCtx: Context, private readonly api: IApiClient) {
-    this.manager = new SessionManager(api)
+  constructor(private readonly rootCtx: Context, api: IApiClient) {
     this.selection = createSnapshotStore<{ sessionId?: SessionId }>(
       {},
       { persist: { name: 'dsh.sessions.current' } })
-    this.list = createSnapshotStore<SessionListState>({ ids: [], byId: {}, current: undefined })
+    this.manager = new SessionManager(api, this.selection.getSnapshot().sessionId)
+    this.list = createSnapshotStore<SessionListState>({
+      ids: [], byId: {}, current: undefined, phase: 'pending',
+    })
     // The manager owns wire truth; the store is its projection. Manager
     // notifications are already microtask-batched.
     this.manager.subscribe(() => { this.projectList() })
@@ -134,69 +211,211 @@ export class SessionsService {
     // 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() })
+    // The current-provide projection follows the same current writes.
+    this.list.subscribe(() => {
+      this.followCurrent()
+      this.updateCurrentProvideInfo()
+    })
+    // The runtime's own contribution comes first: useSession rides the same
+    // provide channel every plugin uses (no renderer special case).
+    this.providers.push({
+      hooks: ['session'],
+      resolve: binding => ({ hooks: { session: binding.session } }),
+    })
+    this.maybeInfo = this.materializeMaybeProvideInfo()
+    this.currentProvideInfoSnapshot = this.maybeInfo
+    this.currentProvideInfo = {
+      getSnapshot: () => this.currentProvideInfoSnapshot,
+      subscribe: (fn) => {
+        this.currentProvideInfoListeners.add(fn)
+        return () => { this.currentProvideInfoListeners.delete(fn) }
+      },
+    }
     rootCtx.reflect.provide('sessions', this, undefined)
   }
 
+  /**
+   * Register a per-session standard-props provider: every session-scope slot
+   * component receives the contributed members as standard props (`hooks`
+   * sources become `use<Name>` selector hooks on the render side; `props`
+   * spread verbatim). Contributions materialize lazily with the session's
+   * scope record and die with it. Registration order is resolution order;
+   * duplicate member names fail loud at materialization.
+   * @param descriptor - static member roster plus per-session resolver.
+   * @returns disposer removing the provider (already-materialized bundles keep their members until their scope drops).
+   */
+  provide(descriptor: SessionProvideDescriptor): () => void {
+    this.providers.push(descriptor)
+    // Scopes may already exist (boot order: the list lands and resolves
+    // scopes before later plugins register) — their bundles must include
+    // every provider by first render, so re-materialize on roster change.
+    this.rematerializeProvideBundles()
+    return () => {
+      const at = this.providers.indexOf(descriptor)
+      if (at >= 0) this.providers.splice(at, 1)
+      this.rematerializeProvideBundles()
+    }
+  }
+
+  /** Rebuild every live scope's standard-props bundle after a provider roster change. */
+  private rematerializeProvideBundles(): void {
+    this.maybeInfo = this.materializeMaybeProvideInfo()
+    for (const record of this.scopes.values()) {
+      record.provideInfo = this.materializeProvideInfo(record.binding)
+    }
+    this.updateCurrentProvideInfo()
+  }
+
+  /**
+   * Re-derive the current selection's provide bundle and publish it when it
+   * changed. Bundles are identity-stable per (scope, roster)
+   * materialization, so an identity compare is exact; synchronous notify —
+   * both call sites (list.subscribe, provide()) already sit behind their own
+   * batching or registration edges.
+   */
+  private updateCurrentProvideInfo(): void {
+    const next = this.maybeProvideInfo(this.list.getSnapshot().current)
+    if (next === this.currentProvideInfoSnapshot) return
+    this.currentProvideInfoSnapshot = next
+    for (const fn of [...this.currentProvideInfoListeners]) {
+      try {
+        fn()
+      } catch (error) {
+        // Contain subscriber failures: this notify runs inside the list
+        // notification, where a throwing render-side subscriber would starve
+        // later listeners and abort the projection pass that scheduled it.
+        console.error('sessions.currentProvideInfo subscriber failed:', error)
+      }
+    }
+  }
+
+  /** Build the static no-session kit and reject duplicate declared names. */
+  private materializeMaybeProvideInfo(): SessionMaybeProvideInfo {
+    const hooks: Record<string, undefined> = {}
+    const props: Record<string, undefined> = {}
+    for (const descriptor of this.providers) {
+      for (const name of descriptor.hooks ?? []) {
+        if (Object.hasOwn(hooks, name)) throw new Error(`sessions.provide: duplicate hook "${name}"`)
+        hooks[name] = undefined
+      }
+      for (const name of descriptor.props ?? []) {
+        if (Object.hasOwn(props, name)) throw new Error(`sessions.provide: duplicate prop "${name}"`)
+        props[name] = undefined
+      }
+    }
+    return { sessionId: undefined, hooks, props } // no projections face: every key reads absent without a session
+  }
+
+  /** Materialize the standard-props bundle for one session (fails loud on duplicate member names). */
+  private materializeProvideInfo(binding: SessionBinding): SessionProvideInfo {
+    const hooks: Record<string, HostObservable<unknown>> = {}
+    const props: Record<string, unknown> = {}
+    for (const descriptor of this.providers) {
+      const contribution = descriptor.resolve(binding)
+      const contributedHooks = contribution.hooks ?? {}
+      const contributedProps = contribution.props ?? {}
+      for (const name of Object.keys(contributedHooks)) {
+        if (!(descriptor.hooks ?? []).includes(name)) {
+          throw new Error(`sessions.provide: undeclared hook "${name}"`)
+        }
+      }
+      for (const name of Object.keys(contributedProps)) {
+        if (!(descriptor.props ?? []).includes(name)) {
+          throw new Error(`sessions.provide: undeclared prop "${name}"`)
+        }
+      }
+      for (const name of descriptor.hooks ?? []) {
+        const source = contributedHooks[name]
+        if (source === undefined) throw new Error(`sessions.provide: missing hook "${name}"`)
+        if (Object.hasOwn(hooks, name)) throw new Error(`sessions.provide: duplicate hook "${name}"`)
+        hooks[name] = source
+      }
+      for (const name of descriptor.props ?? []) {
+        if (!Object.hasOwn(contributedProps, name)) throw new Error(`sessions.provide: missing prop "${name}"`)
+        if (Object.hasOwn(props, name)) throw new Error(`sessions.provide: duplicate prop "${name}"`)
+        props[name] = contributedProps[name]
+      }
+    }
+    return {
+      sessionId: binding.sessionId,
+      hooks,
+      props,
+      // The useProjection seat: key-addressed bare value faces off the
+      // session's projection store (open key space — never a static roster member).
+      projections: { faceOf: key => binding.session.projections.faceOf(key) },
+    }
+  }
+
   /**
    * Select a session as current. Unknown ids fail loud instead of navigating
    * nowhere.
    * @param id - session id (must exist in the list store).
    */
   open(id: SessionId): void {
-    if (this.list.getSnapshot().byId[id] === undefined) {
-      throw new Error(`sessions.open: unknown session ${id}`)
-    }
-    this.selection.update((draft) => { draft.sessionId = id })
-    this.list.update((draft) => { draft.current = id })
+    this.manager.select(id)
   }
 
   /**
    * Clear the current selection so the layout shows the no-session empty
-   * state. Wipes the persisted selection too — a reload stays on empty until
-   * the user opens or starts a session. Staging holds the previous occupant
-   * across the blank (same masked-gap rule as a transient list miss).
+   * state (new-session affordance and the workspace preselection flow).
+   * Wipes the persisted selection too — a reload stays on empty until the
+   * user opens or starts a session. The staged scope keeps its frozen view
+   * per the masked-gap contract until the next open() moves the stage.
    */
   clear(): void {
-    this.selection.set({})
-    this.list.update((draft) => { draft.current = undefined })
+    this.manager.clearSelection()
   }
 
   /**
-   * Create a session on the host.
-   * @param opts - creation options (project directory).
-   * @returns the new session id.
+   * Refresh the real Session baseline, reusing an in-flight pull.
+   * @returns completion of the current or newly started baseline pull.
    */
-  async create(opts: { cwd?: string } = {}): Promise<SessionId> {
-    const result = await this.manager.create(opts.cwd)
-    if (!result.ok) throw new Error(`session create failed: ${result.error.code}: ${result.error.message}`)
+  refresh(): Promise<void> {
+    return this.manager.refreshList()
+  }
+
+  /**
+   * Route a mux stream envelope into the Session object layer.
+   * @param envelope - validated mux stream envelope.
+   */
+  handleMuxEnvelope(envelope: Parameters<SessionManager['handleMuxEnvelope']>[0]): void {
+    this.manager.handleMuxEnvelope(envelope)
+  }
+
+  /**
+   * Route a Host stream envelope into the Session object layer.
+   * @param envelope - validated Host stream envelope.
+   */
+  handleHostEnvelope(envelope: Parameters<SessionManager['handleHostEnvelope']>[0]): void {
+    this.manager.handleHostEnvelope(envelope)
+  }
+
+  /** Rebuild the Session baseline and every opened window after connection. */
+  handleConnected(): void {
+    this.manager.handleConnected()
+  }
+
+  /**
+   * Create a session on the host. Resolution guarantee: by the time the
+   * promise resolves, the created session is in the list store and
+   * {@link SessionsService.binding} resolves it — callers (New Session
+   * draft hand-off) may address the scope synchronously, without waiting a
+   * notifier flush. The synchronous projection below makes this structural
+   * rather than an accident of microtask ordering.
+   * @param opts - target workspace or directory and an optional preallocated id.
+   * @returns the new session id.
+   * @throws {SessionCreateError} with the requested id.
+   */
+  async create(opts: { workspaceId?: WorkspaceId; cwd?: string; sessionId?: SessionId } = {}): Promise<SessionId> {
+    const result = await this.manager.create(opts)
+    if (!result.ok) throw new SessionCreateError(result.error, opts.sessionId)
+    this.projectList()
     return result.value.sessionId
   }
 
   /**
-   * Create a workspace folder under the host process cwd and a session in it.
-   * Name is a single path segment (no separators); the host mkdir runs inside
-   * session.create. Caller opens the returned id when it wants the session staged.
-   * @param name - workspace folder basename.
-   * @returns the new session id.
-   */
-  async createWorkspace(name: string): Promise<SessionId> {
-    const trimmed = name.trim()
-    if (trimmed === '') throw new Error('sessions.createWorkspace: name is required')
-    if (/[/\\]/.test(trimmed)) {
-      throw new Error('sessions.createWorkspace: name must not contain path separators')
-    }
-    const { result } = await this.api.host.describe({})
-    if (!result.ok) {
-      throw new Error(`host.describe failed: ${result.error.code}: ${result.error.message}`)
-    }
-    const hostCwd = result.value.cwd.replace(/[/\\]+$/, '')
-    return this.create({ cwd: `${hostCwd}/${trimmed}` })
-  }
-
-  /**
-   * Resolve a session-scoped context view (use-and-discard).
-   * @param id - session id.
+   * Resolve an Agent-scoped context view (use-and-discard).
+   * @param id - session id (the agent identity — 1:1 same axis).
    * @returns scoped ctx, or undefined for a session neither listed nor already scoped.
    */
   scope(id: SessionId): Context | undefined {
@@ -204,7 +423,7 @@ export class SessionsService {
   }
 
   /**
-   * Read the session scope tag off a context. Service-method seam: fetch
+   * Read the Agent scope tag off a context. Service-method seam: fetch
    * bundles must reach scope resolution through ctx.sessions — a cross-bundle
    * value import of the standalone helper would inline a second module
    * instance whose private tag Symbol never matches.
@@ -212,7 +431,22 @@ export class SessionsService {
    * @returns the session id, or undefined on root contexts.
    */
   scopeOf(ctx: Context): SessionId | undefined {
-    return scopeOf(ctx)
+    return scopeTagOf(ctx)
+  }
+
+  /**
+   * Resolve the business Session behind an Agent-scoped context — the one
+   * hop every scoped consumer (event listeners, per-session controllers)
+   * takes from ctx-space into object-space (the client mirror of host
+   * `agent.session`). Same service-method seam as
+   * {@link SessionsService.scopeOf}.
+   * @param ctx - an Agent-scoped context.
+   * @returns the Session, or undefined when the ctx is untagged or its scope was pruned.
+   */
+  sessionOf(ctx: Context): Session | undefined {
+    const id = scopeTagOf(ctx)
+    if (id === undefined) return undefined
+    return this.scopes.get(id)?.binding.session
   }
 
   /**
@@ -226,16 +460,22 @@ export class SessionsService {
   }
 
   /**
-   * Resolve the render-layer session cell (SessionProvider's feed through
-   * 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.
+   * Resolve one session's render-layer standard-props bundle (ctx never
+   * enters the render layer; the renderer subscribes to
+   * {@link SessionsService.currentProvideInfo}). Pure resolution — render-safe:
+   * no staging, no window side effects (StrictMode double-invokes and
+   * concurrent discarded passes must stay free).
    */
-  cell(id: string): SessionCell | undefined {
-    return this.resolve(id as SessionId)?.cell
+  private provideInfo(id: string): SessionProvideInfo | undefined {
+    return this.resolve(id as SessionId)?.provideInfo
+  }
+
+  /**
+   * Resolve the current-session-optional standard kit. Unknown or absent ids
+   * return the static no-session projection rather than removing hook props.
+   */
+  private maybeProvideInfo(id: string | undefined): SessionMaybeProvideInfo {
+    return (id === undefined ? undefined : this.provideInfo(id)) ?? this.maybeInfo
   }
 
   /**
@@ -246,11 +486,12 @@ export class SessionsService {
    * failed one retries the next time current is touched).
    */
   private followCurrent(): void {
-    const current = this.list.getSnapshot().current
+    const snapshot = this.list.getSnapshot()
+    const current = snapshot.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
+    if (current === undefined || snapshot.byId[current] === undefined || current === this.watched) return
     this.watched = current
     this.sweepDeferred()
     const record = this.resolve(current)
@@ -280,30 +521,42 @@ export class SessionsService {
     return chain
   }
 
-  /** Lazily mint the scope + binding for a listed (or already-scoped) session. */
+  /**
+   * Lazily mint the scope + binding for an eligible session. Eligibility and
+   * prune share one predicate (decision 12): listed on the host — a scope is
+   * born when its session enters the client's view (list mirror row from the
+   * baseline pull, a create() echo, or the session-added frame) and dies with
+   * the prune when the row leaves.
+   */
   private resolve(id: SessionId): ScopeRecord | undefined {
     const existing = this.scopes.get(id)
     if (existing !== undefined) return existing
-    // Frozen scopes outlive the list; new scopes are only minted for listed sessions.
-    if (this.list.getSnapshot().byId[id] === undefined) return undefined
-    const fiber = this.rootCtx.plugin(sessionScope)
-    const ctx = fiber.ctx.extend({ [kScope]: id })
+    if (!this.eligible(id)) return undefined
+    const { fiber, ctx } = createScope(this.rootCtx, id)
     const session = this.manager.get(id)
+    // The Session owns its scoped dispatch point (host Agent.loopCtx mirror);
+    // mint and bind are one step so a live scope record implies a bound actx.
+    session.bindScope(ctx)
+    const binding: SessionBinding = { sessionId: id, session, ctx }
     const record: ScopeRecord = {
       fiber,
       ctx,
-      binding: { sessionId: id, session, ctx },
-      // Bare source form (store migration): the Session object IS the
-      // observable; the React side binds the useSession hook per cell.
-      cell: { sessionId: id, session },
+      binding,
+      // Sources are bare observables; React binds selector hooks at its own seam.
+      provideInfo: this.materializeProvideInfo(binding),
     }
     this.scopes.set(id, record)
     return record
   }
 
+  /** The one aliveness predicate shared by scope mint and prune: host-listed. */
+  private eligible(id: SessionId): boolean {
+    return this.list.getSnapshot().byId[id] !== undefined
+  }
+
   /** Project the manager's list snapshot into the store (title derivation is display-only). */
   private projectList(): void {
-    const items = this.manager.getListSnapshot().items
+    const { items, current, phase } = this.manager.getListSnapshot()
     const ids: SessionId[] = []
     const byId: Record<SessionId, SessionSummary> = {}
     for (const entry of items) {
@@ -313,24 +566,30 @@ export class SessionsService {
         displayTitle: displayTitleOf(entry.title, entry.cwd, entry.sessionId),
         running: entry.running,
         waitingApproval: entry.waitingApproval,
+        blank: entry.blank,
         updatedAt: entry.updatedAt,
         ...(entry.title !== undefined ? { title: entry.title } : {}),
         ...(entry.cwd !== undefined ? { cwd: entry.cwd } : {}),
         ...(entry.parentSessionId !== undefined ? { parentId: entry.parentSessionId } : {}),
       }
     }
-    // current = the persisted selection, masked while its session is absent
-    // (falls to the empty state; resurfaces if the session returns).
-    const selected = this.selection.getSnapshot().sessionId
-    const current = selected !== undefined && byId[selected] !== undefined ? selected : undefined
-    this.list.set({ ids, byId, current })
+    const persisted = this.selection.getSnapshot().sessionId
+    // No current (cleared, or masked gap) wipes the persisted cell — a reload
+    // stays on empty; the in-memory selection still resurfaces a masked id.
+    if (current === undefined) {
+      if (persisted !== undefined) this.selection.set({})
+    } else if (byId[current] !== undefined && persisted !== current) {
+      this.selection.set({ sessionId: current })
+    }
+    this.list.set({ ids, byId, current, phase })
     this.pruneScopes(byId)
   }
 
-  /** Tear down scopes for removed sessions off stage; the staged one defers until the stage moves. */
+  /** Tear down scope + instance for no-longer-eligible sessions off stage; the staged one defers until the stage moves. */
   private pruneScopes(byId: Record<SessionId, SessionSummary>): void {
+    void byId
     for (const [id, record] of this.scopes) {
-      if (byId[id] !== undefined) continue
+      if (this.eligible(id)) continue
       if (id === this.watched) {
         this.deferredRemovals.add(id)
         continue
@@ -341,12 +600,22 @@ export class SessionsService {
     }
   }
 
-  /** Dispose a scope fiber and its session-keyed slot-store instances together (single lifecycle axis). */
+  /**
+   * One teardown for the whole per-session axis (decision 12): the scope
+   * fiber (cascading every actx-registered effect: input shell, slash
+   * controller, popup, plugin stores, listeners), the session-keyed slot
+   * stores, and the Session instance itself — the host session log is the
+   * durable truth, a reopen lazily rebuilds and backfills via open().
+   */
   private dropScope(id: SessionId, record: ScopeRecord): void {
     void record.fiber.dispose()
+    // Release the Session's dispatch point with the scope it belongs to (a
+    // surviving instance — the live Intent — rebinds when resolve re-mints).
+    record.binding.session.unbindScope()
     // Optional lookup: slots and sessions are sibling services with no
     // declared dependency; a slots-less boot (object-layer tests) skips.
     this.rootCtx.get('slots')?.pruneStoreScope(id)
+    this.manager.drop(id)
   }
 
   /** Run deferred teardowns whose session is no longer staged (called when the stage moves). */
@@ -356,8 +625,8 @@ export class SessionsService {
        * 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.)
-      if (this.list.getSnapshot().byId[id] !== undefined) {
+      // Eligible again? (A re-added id cancels the deferred teardown.)
+      if (this.eligible(id)) {
         this.deferredRemovals.delete(id)
         continue
       }

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

@@ -1,8 +1,6 @@
-// Session: wraps every contract call that needs a sessionId + all conversation state for this
-// session (design §A.2/§A.9/§D.2/§D.3). Instances are resident (ruling 2): never destroyed once
-// created, they keep consuming mux frames in the background; React connects directly via
-// subscribe/getSnapshot.
+// Sessions remain resident after creation so they continue consuming mux frames off-screen.
 
+import type { Context } from 'cordis'
 import type { ContentBlock } from '@deepseek-ai/dsh-llm/types'
 import type { SessionEvent } from '@deepseek-ai/dsh-session/types'
 import type {
@@ -14,22 +12,62 @@ import type {
 import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
 import type { ObservableSnapshot } from '../contract/store.ts'
 import type {
-  ConversationNode, ConversationSnapshot, OpenState, PromptError, RunningToolCall,
+  CodeSubCall, ComposerPhase, ConversationNode, ConversationSnapshot, OpenState,
+  PromptError, QueuedMessage, RunningToolCall,
 } from './conversation.ts'
 import type { PendingInteraction } from './pending.ts'
 import { PendingWait } from './pending.ts'
 import { FoldAdapter } from './fold-adapter.ts'
 import { Notifier } from './notifier.ts'
 import { PartialAccumulator } from './partial.ts'
+import { ProjectionValueStore } from './projection-store.ts'
+import type { ProjectionsBaseline } from './projection-store.ts'
 
-/** Messages per page (F.4 ledger: promote to Config at graduation; every call site references this constant). */
+/** Messages requested per history page. */
 export const PAGE_MESSAGES = 50
 
+/** Manager-owned observers of a Session object's local state edges. */
+export interface SessionOptions {
+  /**
+   * First ACCEPTED prompt on a blank session (fires at most once, on the
+   * prompt RPC's success response): the manager mirrors the blank→false flip
+   * into its list row so the session surfaces without waiting for a host
+   * frame. Acceptance is the flip point because it proves the user message
+   * is in the host log; a rejected first prompt keeps the session blank
+   * (hidden, still reusable by connectWorkspace).
+   */
+  onEngaged?(session: Session): void
+  /**
+   * Manager-owned projection value store to adopt (frames route through the
+   * manager and values outlive instantiation); omitted, the Session owns a
+   * private store (bare object-layer construction).
+   */
+  projections?: ProjectionValueStore
+}
+
+/** Queue-row preview cap: the dock renders one line, the full content never leaves the host mirror. */
+const QUEUE_PREVIEW_CHARS = 200
+
+/** Internal inbox-mirror entry: the snapshot row plus the retirement-matching fields the frames carry. */
+interface QueuedEntry {
+  row: QueuedMessage
+  steering: boolean
+  /** JSON-serialized MessageSource (steering retirement matches by source, the host-mirror precedent). */
+  sourceJson: string
+}
+
+/** Single-line queue-row preview: text blocks flattened, non-text as tags, capped by code point. */
+function queuePreviewOf(content: readonly ContentBlock[]): string {
+  const flat = content
+    .map(block => (block.type === 'text' ? block.text : `[${block.type}]`))
+    .join(' ').replace(/\s+/g, ' ').trim()
+  const chars = Array.from(flat)
+  return chars.length > QUEUE_PREVIEW_CHARS ? `${chars.slice(0, QUEUE_PREVIEW_CHARS).join('')}…` : flat
+}
+
 /**
- * Per-session state owner: event window + fold + partial, snapshot out via
- * subscribe/getSnapshot (see the web client architecture RFC). Bare source
- * only (store migration): the React machinery binds the per-cell useSession
- * hook at its own seam — no selector hook member lives on the data layer.
+ * Owns a session's event window, derived conversation state, and observable
+ * snapshot. React bindings remain outside this data layer.
  */
 export class Session implements ObservableSnapshot<ConversationSnapshot> {
   // ---- Window and derived state (all private; the snapshot is the only read surface) ----
@@ -54,8 +92,7 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
    *  Derived from window events (turn/end sweep) — rebuilt by rebuildDerivedFromWindow like partial/openCalls. */
   private frozenNodes: ConversationNode[] = []
   private pending = new Map<string, PendingInteraction>()
-  // Revision counters + caches backing the snapshot's reference-stability contract (§A.9.4/§C.2,
-  // audit S5): buildSnapshot reuses the previous array when the revision is unchanged, so
+  // Revision counters preserve array identity when derived content is unchanged, so
   // React.memo children survive unrelated snapshot swaps (chunk storms must not re-render every
   // tool card and pending card). Mutation sites bump the matching revision. partial needs no
   // counter — PartialAccumulator.toPartial already returns a cached reference when unchanged.
@@ -63,28 +100,95 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   private callsCache: { rev: number; value: RunningToolCall[] } | null = null
   private pendingRev = 0
   private pendingCache: { rev: number; value: PendingInteraction[] } | null = null
+  /** Inbox mirror (session/queued frames + mux-open baseline). Queue frames never hit history,
+   *  so this is stream-only state: reconnect clears it and the fresh baseline re-populates. */
+  private queued: QueuedEntry[] = []
+  private queueRev = 0
+  private queueCache: { rev: number; value: QueuedMessage[] } | null = null
   private frozenRev = 0
   private nodesCache: { folded: readonly ConversationNode[]; frozenRev: number; value: readonly ConversationNode[] } | null = null
+  /** `run_code` sub-dispatches by parent callId (window-derived, like openCalls). Appends
+   *  copy-on-write the per-parent array so published snapshot references never mutate. */
+  private codeDispatches = new Map<string, readonly CodeSubCall[]>()
+  private dispatchesRev = 0
+  private dispatchesCache: { rev: number; value: ReadonlyMap<string, readonly CodeSubCall[]> } | null = null
   private running = false
+  /**
+   * Sticky send marker, private input of the composerPhase derivation: set
+   * synchronously before prompt()'s first await, never reset — the blank →
+   * engaging edge of the phase machine (see ComposerPhase).
+   */
+  private promptAttempted = false
+  /** Empty-log mirror (see ConversationSnapshot.blank); monotone false once flipped. */
+  private blankBit = false
   private removed = false
   private promptError: PromptError | null = null
   private lastAgentError: string | null = null
-  /** Buffer for live events arriving while open/resync is in flight (stitched by seq once history lands, §D.3). */
+  /** Live events buffered during open/resync and stitched by sequence once history lands. */
   private liveBuffer: { event: SessionEvent; view: ToolEventView | undefined }[] = []
-  /** Gap-repair (resync-lite) in flight: acceptLiveEvent detours to liveBuffer until the tail page lands (audit S3). */
+  /** Gap repair in flight; live events detour to the buffer until the tail page lands. */
   private stitching = false
   /** subscribed.lastSeq baseline (gap detection; null when no subscribed frame arrived — degrade to the liveBuffer dedup path). */
   private subscribedLastSeq: number | null = null
 
+  /**
+   * Per-session projection value store (session-projection RFC, push model):
+   * finished whole values computed on the host, seeded by the tail page's
+   * projections block and updated by `session/projection` frames under the
+   * one higher-seq-wins rule. Keys are read via `projections.faceOf(key)`
+   * (the useProjection resolution face); the conversation snapshot never
+   * carries projection values, and no client-side domain folding exists.
+   * Manager-owned when constructed through SessionManager (frames route and
+   * the store outlives instantiation, the title-snapshot precedent); a bare
+   * construction gets a private store.
+   */
+  readonly projections: ProjectionValueStore
+
   private snapshotCache: ConversationSnapshot
   private readonly notifier = new Notifier(() => {
     this.snapshotCache = this.buildSnapshot()
   })
+  /**
+   * Agent-scoped cordis context, bound once by SessionsService when it
+   * mints the scope (the client mirror of the host Agent's loopCtx). The
+   * Session dispatches its own scoped events through it; undefined means
+   * unbound (bare object-layer construction) or already pruned — both skip
+   * dispatch-dependent behavior rather than fail.
+   */
+  private actx: Context | undefined
 
-  constructor(readonly sessionId: SessionId, private readonly api: IApiClient) {
+  /**
+   * @param sessionId - Host session identity (client sessions are always Host-born).
+   * @param api - shared wire client.
+   * @param options - optional manager-owned state observers.
+   */
+  constructor(
+    readonly sessionId: SessionId,
+    private readonly api: IApiClient,
+    private readonly options: SessionOptions = {},
+  ) {
+    this.projections = options.projections ?? new ProjectionValueStore()
     this.snapshotCache = this.buildSnapshot()
   }
 
+  /**
+   * Bind the Agent-scoped context minted by SessionsService (single write;
+   * a second bind is a wiring error and throws). Direction stays one-way at
+   * the seam: consumers still reach the Session via `sessions.sessionOf`,
+   * while the Session holds its own dispatch point (host Agent.loopCtx
+   * mirror).
+   * @param actx - the agent's scoped context.
+   */
+  bindScope(actx: Context): void {
+    if (this.actx !== undefined) throw new Error(`session ${this.sessionId} already has a bound scope`)
+    this.actx = actx
+  }
+
+  /** Release the bound scope at prune time (a later rebind accompanies a freshly minted scope). */
+  unbindScope(): void {
+    this.actx = undefined
+  }
+
   // ---- Operations ----
 
   /**
@@ -96,6 +200,10 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   async prompt(content: ContentBlock[], mode: 'queue' | 'steer'): Promise<RpcResult<{ accepted: true }>> {
     this.promptError = null
     this.lastAgentError = null
+    // Synchronous, before the first await: the blank → engaging edge must be
+    // visible on the session area's very first frame when a caller sends
+    // ahead of navigation (first-send flow).
+    this.promptAttempted = true
     this.notifier.markDirty()
     let result: RpcResult<{ accepted: true }>
     try {
@@ -106,6 +214,18 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
     if (!result.ok) {
       this.promptError = { op: 'send', error: result.error }
       this.notifier.markDirty()
+      return result
+    }
+    // Blank flips on ACCEPTANCE, not attempt: an accepted prompt has logged
+    // its user/message on the host (events.length > 0 is fact, not
+    // optimism), while a rejected first prompt must keep the session blank
+    // — the client-side blank mirror only ever lowers, so flipping early on
+    // a failure would surface the session forever and strip its
+    // connectWorkspace reuse eligibility against the host's authority.
+    if (this.blankBit) {
+      this.blankBit = false
+      this.options.onEngaged?.(this)
+      this.notifier.markDirty()
     }
     return result
   }
@@ -207,6 +327,11 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
    *  in-flight open first — its history request rode the dead connection and must not settle
    *  the fresh generation into 'error' (audit S4). */
   async resync(): Promise<void> {
+    // The queue mirror is NOT cleared here: onConnected (which drives resync)
+    // races the mux frames — the fresh generation's baseline may have landed
+    // already, and the host never resends it. The mirror re-baselines on the
+    // session/subscribed frame instead (same stream as the queue snapshot
+    // that follows it, so ordering is guaranteed).
     if (this.openState === 'cold') return // never opened: no window to rebuild (doOpen flips to 'loading' synchronously, so cold implies no in-flight open)
     this.openGeneration++
     this.openPromise = null
@@ -255,12 +380,36 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   handleMuxEnvelope(rpcId: RpcId, frame: MuxFrame): void {
     switch (frame.type) {
       case 'session/event': {
+        this.retireQueued(frame.event)
         this.acceptLiveEvent(frame.event, frame.view)
         return
       }
+      case 'session/queued': {
+        const message = frame.message
+        // Row key: the enqueueing prompt's rpcId when it rode this wire (the
+        // provisional-echo reconciliation key); otherwise the frame envelope id.
+        const key = 'rpcId' in message.source ? String(message.source.rpcId) : `f:${rpcId}`
+        this.queued.push({
+          row: { key, preview: queuePreviewOf(message.content) },
+          steering: frame.steering,
+          sourceJson: JSON.stringify(message.source),
+        })
+        this.queueRev++
+        this.notifier.markDirty()
+        return
+      }
       case 'session/subscribed': {
         this.subscribedLastSeq = frame.lastSeq
-        return // pure baseline bookkeeping, no visible change
+        // New mux-generation baseline: the host pushes this session's queue
+        // snapshot AFTER the subscribed frame on the same stream, so the
+        // stale mirror clears here — race-free against onConnected/resync
+        // timing (clearing there could wipe a baseline that already landed).
+        if (this.queued.length > 0) {
+          this.queued = []
+          this.queueRev++
+          this.notifier.markDirty()
+        }
+        return
       }
       case 'approval/requested': {
         const { type: _type, sessionId: _sid, ...payload } = frame
@@ -297,11 +446,40 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
    * @param running - the new running state.
    */
   handleRunning(running: boolean): void {
+    // Leave-running sweep (host queuedMirror precedent): discard paths (cancel,
+    // terminal steering drop) have no per-entry frame, so ANY not-running signal
+    // with a nonempty mirror clears it — checked before the equality return so a
+    // stale replay on an already-idle session still sweeps.
+    if (!running && this.queued.length > 0) {
+      this.queued = []
+      this.queueRev++
+      this.notifier.markDirty()
+    }
+    // Turn-start conversion: a blank session never runs, so the first
+    // running:true proves another端's first message landed (设计稿 2.2).
+    if (running && this.blankBit) {
+      this.blankBit = false
+      this.notifier.markDirty()
+    }
     if (this.running === running) return
     this.running = running
     this.notifier.markDirty()
   }
 
+  /**
+   * Blank-bit relay from the authoritative summary source (list baseline and
+   * the session-added frame). Monotone: once any signal (local first send,
+   * running flip, an earlier summary) cleared it, a stale true never
+   * re-blanks.
+   * @param blank - the summary's derived empty-log bit.
+   */
+  handleBlank(blank: boolean): void {
+    if (blank === this.blankBit) return
+    if (blank && (this.promptAttempted || this.running)) return
+    this.blankBit = blank
+    this.notifier.markDirty()
+  }
+
   /** host/session-removed relay: flag the snapshot (instance survives — resident-instance rule). */
   handleRemoved(): void {
     this.removed = true
@@ -317,8 +495,7 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
     this.notifier.markDirty()
   }
 
-  /** Instance-eviction hook, reserved no-op (design §F.6): resident instances are never destroyed
-   *  in v1; an eviction policy lands here (unsubscribe, drop buffers) without touching call sites. */
+  /** No-op because session instances remain resident. */
   dispose(): void {}
 
   // ---- 私有 ----
@@ -350,13 +527,13 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         this.openError = result.error
         return
       }
-      this.installWindow(result.value.events, result.value.hasMore)
+      this.installWindow(result.value.events, result.value.hasMore, result.value.projections)
       // Gap detection (§D.3-4): baseline past the window tail and liveBuffer did not cover it -> pull the tail page once more.
       const tailSeq = this.windowTailSeq()
       if (this.subscribedLastSeq !== null && tailSeq !== null && this.subscribedLastSeq > tailSeq) {
         result = (await this.api.sessions.history({ sessionId: this.sessionId, maxMessages: PAGE_MESSAGES })).result
         if (generation !== this.openGeneration) return
-        if (result.ok) this.installWindow(result.value.events, result.value.hasMore)
+        if (result.ok) this.installWindow(result.value.events, result.value.hasMore, result.value.projections)
       }
       this.openState = 'open'
     } catch (error) {
@@ -373,14 +550,18 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
   /** Install the history window + stitch the liveBuffer (seq is the sole dedup key).
    *  Stitching MUST NOT route through acceptLiveEvent: openState is still 'loading' here
    *  (doOpen flips it after install), so recursing would push every buffered event straight
-   *  back into liveBuffer where nothing ever drains it — a silent drop loop (audit S1). */
-  private installWindow(entries: HistoryEntry[], hasMore: boolean): void {
+   *  back into liveBuffer where nothing ever drains it — a silent drop loop (audit S1).
+   *  A carried projections block seeds the value store (higher seq wins, so a stale
+   *  baseline cannot overwrite a newer push frame); the window events themselves are
+   *  never folded — the host is the only computation site. */
+  private installWindow(entries: HistoryEntry[], hasMore: boolean, projections?: ProjectionsBaseline): void {
     this.events = entries.map(e => e.event)
     this.views = entries.map(e => e.view)
     this.baseSeq = this.events[0]?.seq ?? 0
     this.hasMore = hasMore
     this.foldAdapter.reset(this.events, this.baseSeq, this.views)
     this.rebuildDerivedFromWindow()
+    if (projections !== undefined) this.projections.seed(projections)
     const buffered = this.liveBuffer
     this.liveBuffer = []
     for (const item of buffered) this.appendLive(item.event, item.view)
@@ -429,7 +610,7 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
       const { result } = await this.api.sessions.history({ sessionId: this.sessionId, maxMessages: PAGE_MESSAGES })
       // Failure or superseded by a full resync: drop — the resync path rebuilds and clears the buffer itself.
       if (result.ok && generation === this.openGeneration && this.openState === 'open') {
-        this.installWindow(result.value.events, result.value.hasMore)
+        this.installWindow(result.value.events, result.value.hasMore, result.value.projections)
       }
     } catch (error) {
       console.error('[web-runtime] gap repair failed:', error)
@@ -438,9 +619,89 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
     }
   }
 
+  /** Consumption-event retirement, mirroring the host queuedMirror rules: a message-triggered
+   *  turn/start claims the oldest non-steering entry; a steering/message drains the oldest
+   *  steering entry with the same source (loop-authored steering matches nothing and drops none). */
+  private retireQueued(event: SessionEvent): void {
+    if (this.queued.length === 0) return
+    let index = -1
+    if (event.type === 'turn/start') {
+      if (event.data.trigger.kind !== 'message') return
+      index = this.queued.findIndex(entry => !entry.steering)
+    } else if (event.type === 'steering/message') {
+      const source = JSON.stringify(event.data.message.source)
+      index = this.queued.findIndex(entry => entry.steering && entry.sourceJson === source)
+    } else {
+      return
+    }
+    if (index < 0) return
+    this.queued.splice(index, 1)
+    this.queueRev++
+    this.notifier.markDirty()
+  }
+
   /** Per-event side effects (right column of the §A.9 dispatch table):
    *  chunk accumulation / partial clear on finalize / openCalls add-remove. */
   private applyEventSideEffects(event: SessionEvent, view?: ToolEventView): void {
+    // The `tool/code-dispatch-start`/`tool/code-dispatch` pair is declared by
+    // the host-side dsh-tools plugin whose types cannot enter the client
+    // program (its host Context merges collide with the client's), so this
+    // wire consumer narrows them structurally — the same posture as every
+    // other cross-wire event payload.
+    if ((event.type as string) === 'tool/code-dispatch-start') {
+      // A started sub-dispatch enters the index as a RunningToolCall — the
+      // exact shape a native in-flight call renders from — under its parent
+      // run_code callId; it never joins the surface flow.
+      const data = event.data as unknown as {
+        parentCallId: string
+        subCallId: string
+        name: string
+        arguments: unknown
+      }
+      const running: CodeSubCall = {
+        callId: data.subCallId, name: data.name,
+        argsRaw: JSON.stringify(data.arguments),
+        turn: 0, step: 0, time: event.time, callView: null,
+      }
+      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
+      this.codeDispatches.set(data.parentCallId, [...siblings, running])
+      this.dispatchesRev++
+      return
+    }
+    if ((event.type as string) === 'tool/code-dispatch') {
+      // Settlement replaces the running entry in place (same array position,
+      // so parallel sub-calls keep their start order) with the
+      // ToolResultNode form; a settle with no observed start (history window
+      // cut mid-pair, or a pre-start-event log) appends directly.
+      const data = event.data as unknown as {
+        parentCallId: string
+        subCallId: string
+        name: string
+        arguments: unknown
+        isError: boolean
+        content: ContentBlock[]
+      }
+      const siblings = this.codeDispatches.get(data.parentCallId) ?? []
+      const at = siblings.findIndex(sub => sub.callId === data.subCallId)
+      const started = at === -1 ? undefined : siblings[at]
+      const settled: CodeSubCall = {
+        kind: 'tool-result', seq: event.seq, time: event.time,
+        callId: data.subCallId,
+        call: { name: data.name, argsRaw: JSON.stringify(data.arguments) },
+        // Duration source: the paired start's time when observed; null =
+        // unknown (settle-only window), matching the native tool-result
+        // contract so views never present a fabricated zero duration.
+        callTime: started === undefined ? null : started.time,
+        content: data.content, isError: data.isError,
+        callView: null, resultView: null,
+      }
+      this.codeDispatches.set(
+        data.parentCallId,
+        at === -1 ? [...siblings, settled] : siblings.map((sub, index) => (index === at ? settled : sub)),
+      )
+      this.dispatchesRev++
+      return
+    }
     switch (event.type) {
       case 'assistant/chunk': {
         const { turn, step, chunk } = event.data
@@ -466,7 +727,7 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         return
       }
       case 'tool/result': {
-        if (this.openCalls.delete(String(event.data.callId))) this.callsRev++
+        if (this.openCalls.delete(String(event.data.message.source.callId))) this.callsRev++
         return
       }
       case 'turn/end': {
@@ -520,6 +781,8 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
     this.callsRev++
     this.frozenNodes = []
     this.frozenRev++
+    this.codeDispatches = new Map()
+    this.dispatchesRev++
     for (let i = 0; i < this.events.length; i++) {
       const event = this.events[i]
       /* v8 ignore next -- dense-array guard: i stays within events.length, so the undefined arm needs a sparse array no caller builds. */
@@ -552,21 +815,50 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
     if (this.pendingCache === null || this.pendingCache.rev !== this.pendingRev) {
       this.pendingCache = { rev: this.pendingRev, value: [...this.pending.values()] }
     }
+    if (this.dispatchesCache === null || this.dispatchesCache.rev !== this.dispatchesRev) {
+      this.dispatchesCache = { rev: this.dispatchesRev, value: new Map(this.codeDispatches) }
+    }
+    if (this.queueCache === null || this.queueCache.rev !== this.queueRev) {
+      this.queueCache = { rev: this.queueRev, value: this.queued.map(entry => entry.row) }
+    }
+    const partial = this.partial?.toPartial() ?? null
     return {
       sessionId: this.sessionId,
       nodes,
       foldDegraded: degraded,
-      partial: this.partial?.toPartial() ?? null,
+      partial,
       runningCalls: this.callsCache.value,
       pending: this.pendingCache.value,
+      codeDispatches: this.dispatchesCache.value,
+      queue: this.queueCache.value,
       running: this.running,
+      composerPhase: derivePhase(
+        nodes.length > 0 || partial !== null || this.running || this.pendingCache.value.length > 0,
+        this.promptAttempted,
+      ),
       removed: this.removed,
       openState: this.openState,
       openError: this.openError,
       hasMore: this.hasMore,
       loadingOlder: this.loadingOlder,
       promptError: this.promptError,
+      blank: this.blankBit,
       lastAgentError: this.lastAgentError,
     }
   }
 }
+
+/**
+ * The composerPhase judgment — the single site that knows the predicate
+ * (consumers switch on the result, never re-derive). Monotone per session
+ * object: `hasContent` only grows within a window and `promptAttempted` is
+ * sticky, so blank → engaging → active never steps back; a failed first
+ * prompt stays engaging (retry semantics — see ComposerPhase).
+ * @param hasContent - any conversation material exists (nodes, partial, running turn, pending waits).
+ * @param promptAttempted - a prompt was initiated on this session object.
+ * @returns the derived phase.
+ */
+function derivePhase(hasContent: boolean, promptAttempted: boolean): ComposerPhase {
+  if (hasContent) return 'active'
+  return promptAttempted ? 'engaging' : 'blank'
+}

packages/client/runtime/src/client/slots.ts

@@ -235,19 +235,16 @@ export class SlotsService extends Service {
     }
   }
 
-  /** Build (once) the host face the installed renderer reads; sessions resolve lazily at first render. */
+  /** Build once after both object-layer services mount; per-session provide bundles still resolve lazily. */
   private hostFace(): SlotRendererHost {
     if (this._host !== undefined) return this._host
     const sessions = this.ctx.get('sessions')
     if (sessions === undefined) {
       throw new Error("renderSlot('root') before the sessions service mounted — boot order puts runtime apply first")
     }
-    // Identity-stable view: current rides the list snapshot (arbitrated), but
-    // the provider consumes it as its own observable; one cached object keeps
-    // the renderer's per-source hook cache stable.
-    const current = {
-      getSnapshot: () => sessions.list.getSnapshot().current as string | undefined,
-      subscribe: (fn: () => void) => sessions.list.subscribe(fn),
+    const workspaces = this.ctx.get('workspaces')
+    if (workspaces === undefined) {
+      throw new Error("renderSlot('root') before the workspaces service mounted — boot order puts runtime apply first")
     }
     this._host = {
       subscribe: (key, fn) => this._core.subscribe(key, fn),
@@ -259,9 +256,9 @@ export class SlotsService extends Service {
         entry.store === undefined ? undefined : this.resolveStore(entry.store as unknown as EngineStoreHandle, scopeKey),
       sessions: {
         list: sessions.list,
-        current,
-        cell: id => sessions.cell(id),
+        provideInfo: sessions.currentProvideInfo,
       },
+      workspaces: { list: workspaces.list },
     }
     return this._host
   }
@@ -270,13 +267,13 @@ export class SlotsService extends Service {
   private resolveStore(handle: EngineStoreHandle, sessionId: string | undefined): StoreInstanceLike {
     const record = this._stores.get(handle)
     if (record === undefined) throw new Error('store handle is not registered (entry unloaded, or the handle never went through register)')
-    const key = record.scope === 'session' ? sessionId : ROOT_INSTANCE_KEY
-    if (key === undefined) throw new Error('session-scoped store resolution requires a session id')
+    const key = record.scope === 'root' ? ROOT_INSTANCE_KEY : sessionId
+    if (key === undefined) throw new Error(`${record.scope} store resolution requires a session id`)
     let instance = record.instances.get(key)
     if (instance === undefined) {
       // Session instances get the scope key (the engine suffixes the persist
       // key per session); root instances stay keyless.
-      instance = record.scope === 'session' ? handle.create(key) : handle.create()
+      instance = record.scope === 'root' ? handle.create() : handle.create(key)
       record.instances.set(key, instance)
     }
     return instance

packages/client/runtime/src/client/workspaces/manager.ts

@@ -0,0 +1,289 @@
+/** Workspace baseline, incremental-frame, and unary-action owner. */
+
+import type {
+  HostFrame, IApiClient, RpcError, RpcRequest, RpcResult, SessionId, WorkspaceId, WorkspaceView,
+} from '@deepseek-ai/dsh-client-connection/client'
+import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
+import { mergeOrderedBaseline } from '../ordered-baseline.ts'
+import { Notifier } from '../sessions/notifier.ts'
+import { Workspace, type WorkspaceCreateInput } from './workspace.ts'
+
+/** Monotone workspace-list arrival lifecycle. */
+export type WorkspaceListPhase = 'pending' | 'ready'
+
+/** Immutable workspace-list snapshot. */
+export interface WorkspaceListSnapshot {
+  items: readonly WorkspaceView[]
+  state: 'idle' | 'loading' | 'error'
+  phase: WorkspaceListPhase
+  error: RpcError | null
+}
+
+type WorkspaceDelta =
+  | { type: 'upsert'; workspace: WorkspaceView }
+  | { type: 'remove'; workspaceId: WorkspaceId }
+
+/** Workspace object cluster driven by one list baseline and changed-frame upserts. */
+export class WorkspaceManager {
+  private items: Workspace[] = []
+  private itemViewsSource: readonly Workspace[] | null = null
+  private itemViewsCache: readonly WorkspaceView[] = []
+  private state: WorkspaceListSnapshot['state'] = 'idle'
+  private phase: WorkspaceListPhase = 'pending'
+  private error: RpcError | null = null
+  private inflight: Promise<void> | null = null
+  private refreshFrames: WorkspaceDelta[] | null = null
+  /**
+   * Ids this process has seen removed, kept for the connection's lifetime so
+   * a late changed frame or a stale baseline row cannot resurrect a deleted
+   * row. Correctness rests on Host ids never being reused (the registry mints
+   * a fresh `randomUUID` per record, including when the same directory is
+   * registered again) — a path-derived id scheme would turn these entries
+   * into permanent blindfolds and must clear them instead.
+   */
+  private readonly removedIds = new Set<WorkspaceId>()
+  private snapshotCache: WorkspaceListSnapshot
+  private readonly notifier = new Notifier(() => {
+    this.snapshotCache = this.buildSnapshot()
+  })
+
+  /** @param api - shared wire client. */
+  constructor(private readonly api: IApiClient) {
+    this.snapshotCache = this.buildSnapshot()
+  }
+
+  /**
+   * Refresh from workspace.list. The first successful response establishes
+   * Host order; later responses update membership and values without moving
+   * identities already visible to the client. Frames arriving during the RPC
+   * are replayed over its response.
+   * @returns the shared in-flight refresh.
+   */
+  refresh(): Promise<void> {
+    if (this.inflight !== null) return this.inflight
+    this.state = 'loading'
+    this.error = null
+    const established = this.itemViews()
+    const frames: WorkspaceDelta[] = []
+    this.refreshFrames = frames
+    this.notifier.markDirty()
+    this.inflight = (async () => {
+      try {
+        const { result } = await this.api.workspace.list({})
+        if (result.ok) {
+          let items = this.phase === 'pending'
+            ? result.value.items
+            : mergeOrderedBaseline(established, result.value.items, workspace => workspace.workspaceId)
+          items = items.filter(workspace => !this.removedIds.has(workspace.workspaceId))
+          for (const delta of frames) items = applyWorkspaceDelta(items, delta)
+          this.installViews(items)
+          this.state = 'idle'
+          this.phase = 'ready'
+        } else {
+          this.state = 'error'
+          this.error = result.error
+        }
+      } catch (error) {
+        this.state = 'error'
+        const folded = transportError<never>(error)
+        /* v8 ignore next -- transportError always returns the failure branch. */
+        this.error = folded.ok ? null : folded.error
+      } finally {
+        this.refreshFrames = null
+        this.inflight = null
+        this.notifier.markDirty()
+      }
+    })()
+    return this.inflight
+  }
+
+  /**
+   * Create or resolve a real Workspace, then publish its returned snapshot
+   * without waiting for the changed frame.
+   * @param input - name under workspaceRoot or an existing absolute path.
+   * @returns the wire result.
+   */
+  async create(input: WorkspaceCreateInput): Promise<RpcResult<{ workspace: WorkspaceView; created: boolean }>> {
+    const workspace = new Workspace(this.api, input)
+    const completion = workspace.materialize()
+    if (completion === undefined) throw new Error('a local Workspace must be materializable')
+    const result = await completion
+    if (result.ok) this.upsert(result.value.workspace, workspace)
+    return result
+  }
+
+  /**
+   * Rename a Workspace, then publish its returned snapshot without waiting
+   * for the changed frame.
+   * @param workspaceId - target workspace.
+   * @param title - new display title.
+   * @returns the wire result.
+   */
+  async rename(workspaceId: WorkspaceId, title: string): Promise<RpcResult<{ workspace: WorkspaceView }>> {
+    const { result } = await this.api.workspace.rename({ workspaceId, title })
+    if (result.ok) this.upsert(result.value.workspace)
+    return result
+  }
+
+  /**
+   * Delete a Workspace registration and remove its local projection from the
+   * unary response without waiting for the Host frame.
+   * @param workspaceId - target workspace.
+   * @returns the wire result.
+   */
+  async delete(workspaceId: WorkspaceId): Promise<RpcResult<{ deleted: true }>> {
+    const { result } = await this.api.workspace.delete({ workspaceId })
+    if (result.ok) this.remove(workspaceId, true)
+    return result
+  }
+
+  /**
+   * Move a session within its Workspace's manual order, then publish the
+   * returned snapshot without waiting for the changed frame.
+   * @param workspaceId - owning workspace.
+   * @param sessionId - accounted session to move.
+   * @param beforeSessionId - accounted anchor to insert before; omitted appends.
+   * @returns the wire result.
+   */
+  async insertSessionBefore(
+    workspaceId: WorkspaceId,
+    sessionId: SessionId,
+    beforeSessionId?: SessionId,
+  ): Promise<RpcResult<{ workspace: WorkspaceView }>> {
+    const { result } = await this.api.workspace.insertSessionBefore({
+      workspaceId, sessionId,
+      ...beforeSessionId === undefined ? {} : { beforeSessionId },
+    })
+    if (result.ok) this.upsert(result.value.workspace)
+    return result
+  }
+
+  /**
+   * Host-frame entry. Non-workspace frames are ignored so the runtime can
+   * fan one host stream out to both object managers.
+   * @param envelope - host stream envelope.
+   */
+  handleHostEnvelope(envelope: RpcRequest<HostFrame>): void {
+    if (envelope.payload.type === 'host/workspace-changed') this.upsert(envelope.payload.workspace)
+    else if (envelope.payload.type === 'host/workspace-removed') this.remove(envelope.payload.workspaceId)
+  }
+
+  /** Re-pull the baseline after each connection generation. */
+  handleConnected(): void {
+    void this.refresh()
+  }
+
+  /**
+   * Subscribe to workspace snapshot invalidation.
+   * @param listener - snapshot invalidation callback.
+   * @returns unsubscribe function.
+   */
+  subscribe(listener: () => void): () => void {
+    return this.notifier.subscribe(listener)
+  }
+
+  /**
+   * Read the cached workspace snapshot after flushing pending notifications.
+   * @returns the cached workspace snapshot.
+   */
+  getSnapshot(): WorkspaceListSnapshot {
+    this.notifier.ensureFresh()
+    return this.snapshotCache
+  }
+
+  private buildSnapshot(): WorkspaceListSnapshot {
+    return {
+      items: this.itemViews(),
+      state: this.state,
+      phase: this.phase,
+      error: this.error,
+    }
+  }
+
+  /** Upsert one Host view, optionally retaining the local object that materialized it. */
+  private upsert(view: WorkspaceView, identity?: Workspace): void {
+    if (this.removedIds.has(view.workspaceId)) return
+    this.refreshFrames?.push({ type: 'upsert', workspace: view })
+    const index = this.items.findIndex(item => item.getSnapshot().view?.workspaceId === view.workspaceId)
+    // Mutation responses and changed frames race (two carriers, no ordering):
+    // reject a snapshot strictly older than the installed projection so a
+    // late unary response cannot roll back a newer frame.
+    const installed = index === -1 ? undefined : this.items[index]?.getSnapshot().view
+    if (installed !== undefined && Date.parse(view.updatedAt) < Date.parse(installed.updatedAt)) return
+    if (identity !== undefined) {
+      this.items = index === -1
+        ? [identity, ...this.items]
+        : this.items.map((item, position) => position === index ? identity : item)
+    } else if (index === -1) {
+      this.items = [new Workspace(this.api, view), ...this.items]
+    } else {
+      this.items[index]?.adopt(view)
+      this.items = [...this.items]
+    }
+    this.notifier.markDirty()
+  }
+
+  /** Remove one id idempotently and retain a tombstone against late echoes. */
+  private remove(workspaceId: WorkspaceId, direct = false): void {
+    this.refreshFrames?.push({ type: 'remove', workspaceId })
+    this.removedIds.add(workspaceId)
+    const items = this.items.filter(item =>
+      item.getSnapshot().view?.workspaceId !== workspaceId)
+    if (items.length === this.items.length) {
+      // The Host frame may have removed the row first but left its batched
+      // notification pending. A successful unary echo still flushes that
+      // committed state before the user action resolves.
+      if (direct) this.notifier.notifyNow()
+      return
+    }
+    this.items = items
+    if (direct) this.notifier.notifyNow()
+    else this.notifier.markDirty()
+  }
+
+  private installViews(views: readonly WorkspaceView[]): void {
+    const existing = new Map(
+      this.items.flatMap((workspace) => {
+        const view = workspace.getSnapshot().view
+        return view === undefined ? [] : [[view.workspaceId, workspace] as const]
+      }),
+    )
+    const installed = new Map<WorkspaceView['workspaceId'], Workspace>()
+    for (const view of views) {
+      const duplicate = installed.get(view.workspaceId)
+      if (duplicate !== undefined) {
+        duplicate.adopt(view)
+        continue
+      }
+      const workspace = existing.get(view.workspaceId) ?? new Workspace(this.api, view)
+      workspace.adopt(view)
+      installed.set(view.workspaceId, workspace)
+    }
+    this.items = [...installed.values()]
+  }
+
+  private itemViews(): readonly WorkspaceView[] {
+    if (this.itemViewsSource === this.items) return this.itemViewsCache
+    this.itemViewsSource = this.items
+    this.itemViewsCache = this.items.flatMap((workspace) => {
+      const view = workspace.getSnapshot().view
+      return view === undefined ? [] : [view]
+    })
+    return this.itemViewsCache
+  }
+}
+
+/** Known ids retain their position; a newly created Workspace enters first. */
+function upsertWorkspace(items: readonly WorkspaceView[], workspace: WorkspaceView): WorkspaceView[] {
+  const index = items.findIndex(item => item.workspaceId === workspace.workspaceId)
+  return index === -1
+    ? [workspace, ...items]
+    : items.map((item, position) => position === index ? workspace : item)
+}
+
+/** Replay one ordered delta over a baseline: upsert in place, or drop the removed id. */
+function applyWorkspaceDelta(items: readonly WorkspaceView[], delta: WorkspaceDelta): WorkspaceView[] {
+  return delta.type === 'upsert'
+    ? upsertWorkspace(items, delta.workspace)
+    : items.filter(workspace => workspace.workspaceId !== delta.workspaceId)
+}

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

@@ -0,0 +1,291 @@
+/** WorkspacesService projects the Workspace object manager for UI consumers. */
+
+import type { Context } from 'cordis'
+import type {
+  IApiClient, RpcError, SessionId, WorkspaceId, WorkspaceView,
+} from '@deepseek-ai/dsh-client-connection/client'
+import type { SnapshotStore } from '../contract/store.ts'
+import { createSnapshotStore } from '../contract/store.ts'
+import type { SessionsService } from '../sessions/service.ts'
+import { WorkspaceManager, type WorkspaceListPhase } from './manager.ts'
+
+/** Workspace list plus the two-baseline readiness and default-target projection. */
+export interface WorkspaceListState {
+  items: readonly WorkspaceView[]
+  state: 'idle' | 'loading' | 'error'
+  phase: WorkspaceListPhase
+  error: RpcError | null
+  /** True only after both workspace.list and session.list have succeeded. */
+  baselinesReady: boolean
+  /** Most recently active Workspace, derived without changing `items` order. */
+  recentWorkspaceId: WorkspaceId | undefined
+}
+
+/** Structured create failure for UI flows that distinguish Host business errors. */
+export class WorkspaceCreateError extends Error {
+  constructor(readonly rpcError: RpcError) {
+    super(`workspace create failed: ${rpcError.code}: ${rpcError.message}`)
+    this.name = 'WorkspaceCreateError'
+  }
+}
+
+/** Real Workspace object layer and Host actions. */
+export class WorkspacesService {
+  /** UI-facing immutable projection; the manager remains wire truth. */
+  readonly list: SnapshotStore<WorkspaceListState>
+  /** Workspace baseline and frame owner. */
+  private readonly manager: WorkspaceManager
+  /** In-flight blank-session creates keyed by workspace (connectWorkspace coalescing). */
+  private readonly connecting = new Map<WorkspaceId, Promise<SessionId>>()
+  /** Guards the runtime-owned one-shot initial-selection subscription. */
+  private initialSelectionStarted = false
+
+  /**
+   * @param ctx - client root context.
+   * @param api - shared wire client.
+   * @param sessions - lower-level Session service used for recency and blank-session reuse.
+   */
+  constructor(ctx: Context, private readonly api: IApiClient, private readonly sessions: SessionsService) {
+    this.manager = new WorkspaceManager(api)
+    this.list = createSnapshotStore<WorkspaceListState>({
+      items: [], state: 'idle', phase: 'pending', error: null,
+      baselinesReady: false, recentWorkspaceId: undefined,
+    })
+    this.manager.subscribe(() => { this.project() })
+    this.sessions.list.subscribe(() => { this.project() })
+    ctx.reflect.provide('workspaces', this, undefined)
+  }
+
+  /**
+   * Resolve the session a New Session flow lands in once this Workspace is
+   * chosen: reuse the workspace's existing blank session when one is in the
+   * list mirror, else create a fresh one on the host (`session.create` births
+   * the full Session+Agent — the client holds no intermediate state). The
+   * caller owns navigation: take the returned id to `sessions.open`.
+   * Resolution guarantee (both arms): the returned id is already in the list
+   * store and `sessions.binding(id)` resolves synchronously — draft hand-off
+   * may write the new scope's machine before opening.
+   * @param workspaceId - chosen Workspace (must be in the workspace list).
+   * @returns the reused or newly created session id.
+   */
+  async connectWorkspace(workspaceId: WorkspaceId): Promise<SessionId> {
+    const workspace = this.list.getSnapshot().items.find(item => item.workspaceId === workspaceId)
+    if (workspace === undefined) throw new Error(`workspaces.connectWorkspace: unknown workspace ${workspaceId}`)
+    // Coalesce concurrent connects: a create's summary lands without cwd
+    // until the host frame arrives, so a second call inside that window
+    // would miss the reuse scan and mint another hidden blank session.
+    const inflight = this.connecting.get(workspaceId)
+    if (inflight !== undefined) return inflight
+    // Reuse: blank && same canonical cwd (workspace.path is the host realpath
+    // canon; summary cwd is the session header passthrough of the same canon).
+    const sessions = this.sessions.list.getSnapshot()
+    for (const id of sessions.ids) {
+      const summary = sessions.byId[id]
+      if (summary !== undefined && summary.blank && summary.cwd === workspace.path) return summary.id
+    }
+    const attempt = this.sessions.create({ workspaceId })
+      .finally(() => { this.connecting.delete(workspaceId) })
+    this.connecting.set(workspaceId, attempt)
+    return attempt
+  }
+
+  /**
+   * Follow the first complete Workspace/Session baseline and select a default
+   * session exactly once. A restored current session wins; otherwise the most
+   * recent Workspace is connected (reusing or creating its blank session).
+   * Later explicit clears stay cleared instead of retriggering this startup
+   * policy. A failed connect may retry on the next baseline projection.
+   * @returns disposer for the baseline subscription; late work cannot navigate after disposal.
+   */
+  startInitialSelection(): () => void {
+    if (this.initialSelectionStarted) {
+      throw new Error('workspaces.startInitialSelection: already started')
+    }
+    this.initialSelectionStarted = true
+    let state: 'waiting' | 'connecting' | 'done' = 'waiting'
+    let disposed = false
+    const reconcile = (): void => {
+      if (disposed || state !== 'waiting') return
+      const workspace = this.list.getSnapshot()
+      if (!workspace.baselinesReady) return
+      const current = this.sessions.list.getSnapshot().current
+      const target = workspace.recentWorkspaceId
+      if (current !== undefined || target === undefined) {
+        state = 'done'
+        return
+      }
+      state = 'connecting'
+      void this.connectWorkspace(target).then(
+        (sessionId) => {
+          if (disposed) return
+          if (this.sessions.list.getSnapshot().current === undefined) {
+            this.sessions.open(sessionId)
+          }
+          state = 'done'
+        },
+        (reason: unknown) => {
+          if (disposed) return
+          state = 'waiting'
+          console.warn('initial workspace selection failed:', reason)
+        },
+      )
+    }
+    const unsubscribe = this.list.subscribe(reconcile)
+    reconcile()
+    return () => {
+      disposed = true
+      unsubscribe()
+    }
+  }
+
+  /**
+   * The shared New Session action behind the shell entry points (sidebar
+   * button, workspace browser): resolve the target Workspace — explicit wins,
+   * else the recent-Workspace projection — connect its blank session and
+   * navigate there; with no Workspace at all, clear the selection into the
+   * New Session view state. Connect failures are non-fatal (console
+   * diagnostics; the current view stays usable).
+   * @param workspaceId - explicit target Workspace for scoped actions.
+   */
+  startSession(workspaceId?: WorkspaceId): void {
+    const target = workspaceId ?? this.list.getSnapshot().recentWorkspaceId
+    if (target === undefined) {
+      this.sessions.clear()
+      return
+    }
+    void this.connectWorkspace(target).then(
+      (sessionId) => { this.sessions.open(sessionId) },
+      (reason: unknown) => { console.warn('new session failed:', reason) },
+    )
+  }
+
+  /**
+   * Create a Workspace by name or register an existing path.
+   * @param input - exactly one Host create spelling.
+   * @returns the created or idempotently resolved Workspace.
+   */
+  async create(input: { name: string } | { path: string }): Promise<WorkspaceView> {
+    const result = await this.manager.create(input)
+    if (!result.ok) throw new WorkspaceCreateError(result.error)
+    return result.value.workspace
+  }
+
+  /**
+   * Open the Host's native directory picker.
+   * @returns the selected path, or null when the user cancelled.
+   */
+  async pickDirectory(): Promise<string | null> {
+    const response = await this.api.host.pickDirectory({})
+    if (!response.result.ok) {
+      throw new Error(`directory picker failed: ${response.result.error.message}`)
+    }
+    return response.result.value.path
+  }
+
+  /**
+   * Open a filesystem path with the Host operating system's default application.
+   * @param path - absolute or host-resolvable path.
+   */
+  async openPath(path: string): Promise<void> {
+    const response = await this.api.host.openPath({ path })
+    if (!response.result.ok) {
+      throw new Error(`path open failed: ${response.result.error.message}`)
+    }
+  }
+
+  /**
+   * Rename a Workspace.
+   * @param workspaceId - target workspace.
+   * @param title - new display title (trimmed non-empty by the Host).
+   * @returns the renamed Workspace view.
+   */
+  async rename(workspaceId: WorkspaceId, title: string): Promise<WorkspaceView> {
+    const result = await this.manager.rename(workspaceId, title)
+    if (!result.ok) throw new Error(`workspace rename failed: ${result.error.code}: ${result.error.message}`)
+    return result.value.workspace
+  }
+
+  /**
+   * Delete one Workspace registration. Sessions, session logs, and the
+   * directory remain Host-owned outside this operation.
+   * @param workspaceId - target workspace.
+   */
+  async delete(workspaceId: WorkspaceId): Promise<void> {
+    const result = await this.manager.delete(workspaceId)
+    if (!result.ok) throw new Error(`workspace delete failed: ${result.error.code}: ${result.error.message}`)
+  }
+
+  /**
+   * Move a session within its Workspace's manual order (DOM-insertBefore-like).
+   * @param workspaceId - owning workspace.
+   * @param sessionId - accounted session to move.
+   * @param beforeSessionId - accounted anchor to insert before; omitted appends.
+   * @returns the updated Workspace view.
+   */
+  async insertSessionBefore(
+    workspaceId: WorkspaceId,
+    sessionId: SessionId,
+    beforeSessionId?: SessionId,
+  ): Promise<WorkspaceView> {
+    const result = await this.manager.insertSessionBefore(workspaceId, sessionId, beforeSessionId)
+    if (!result.ok) throw new Error(`workspace move failed: ${result.error.code}: ${result.error.message}`)
+    return result.value.workspace
+  }
+
+  /**
+   * Refresh the workspace baseline, reusing an in-flight pull.
+   * @returns completion of the current or newly started workspace baseline pull.
+   */
+  refresh(): Promise<void> {
+    return this.manager.refresh()
+  }
+
+  /**
+   * Route a Host stream envelope into the Workspace object layer.
+   * @param envelope - validated Host stream envelope.
+   */
+  handleHostEnvelope(envelope: Parameters<WorkspaceManager['handleHostEnvelope']>[0]): void {
+    this.manager.handleHostEnvelope(envelope)
+  }
+
+  /** Rebuild the Workspace baseline after connection. */
+  handleConnected(): void {
+    this.manager.handleConnected()
+  }
+
+  private project(): void {
+    const workspace = this.manager.getSnapshot()
+    const sessions = this.sessions.list.getSnapshot()
+    const baselinesReady = workspace.phase === 'ready' && sessions.phase === 'ready'
+    this.list.set({
+      items: workspace.items,
+      state: workspace.state,
+      phase: workspace.phase,
+      error: workspace.error,
+      baselinesReady,
+      recentWorkspaceId: baselinesReady ? recentWorkspace(workspace.items, sessions.byId) : undefined,
+    })
+  }
+}
+
+/** Stable tie-breaking follows Host Workspace order. */
+function recentWorkspace(
+  workspaces: readonly WorkspaceView[],
+  sessions: ReturnType<SessionsService['list']['getSnapshot']>['byId'],
+): WorkspaceId | undefined {
+  let selected: WorkspaceId | undefined
+  let selectedTime = Number.NEGATIVE_INFINITY
+  for (const workspace of workspaces) {
+    let latest = Number.NEGATIVE_INFINITY
+    for (const sessionId of workspace.sessionIds) {
+      const session = sessions[sessionId]
+      if (session !== undefined) latest = Math.max(latest, session.updatedAt)
+    }
+    if (latest === Number.NEGATIVE_INFINITY) latest = Date.parse(workspace.createdAt)
+    if (selected === undefined || latest > selectedTime) {
+      selected = workspace.workspaceId
+      selectedTime = latest
+    }
+  }
+  return selected
+}

packages/client/runtime/src/client/workspaces/workspace.ts

@@ -0,0 +1,143 @@
+/** React-free Workspace entity with a client-local materialization lifecycle. */
+
+import type {
+  IApiClient, RpcResult, WorkspaceView,
+} from '@deepseek-ai/dsh-client-connection/client'
+import { transportError } from '@deepseek-ai/dsh-host-apiproxy/api'
+import type { ObservableSnapshot } from '../contract/store.ts'
+import { Notifier } from '../sessions/notifier.ts'
+
+/** Host input retained by a local Workspace until materialization succeeds. */
+export type WorkspaceCreateInput = { name: string } | { path: string }
+
+/** Observable state of a client-local Workspace intent. */
+export interface WorkspaceIntentSnapshot {
+  name: string
+  phase: 'ready' | 'creating'
+  error?: string
+}
+
+/** A Workspace is either a local intent or a materialized Host view. */
+export interface WorkspaceSnapshot {
+  view: WorkspaceView | undefined
+  intent: WorkspaceIntentSnapshot | undefined
+}
+
+interface WorkspaceIntent {
+  input: WorkspaceCreateInput
+  snapshot: WorkspaceIntentSnapshot
+}
+
+/**
+ * Observable Workspace object whose identity survives Host materialization.
+ * Local instances retain their create input and failure state; materialized
+ * instances expose the latest Host view.
+ */
+export class Workspace implements ObservableSnapshot<WorkspaceSnapshot> {
+  private view: WorkspaceView | undefined
+  private intent: WorkspaceIntent | undefined
+  private materialization: Promise<RpcResult<{ workspace: WorkspaceView; created: boolean }>> | null = null
+  private snapshotCache: WorkspaceSnapshot
+  private readonly notifier = new Notifier(() => {
+    this.snapshotCache = this.buildSnapshot()
+  })
+
+  /**
+   * @param api - shared wire client.
+   * @param source - local create input or an existing Host Workspace view.
+   */
+  constructor(private readonly api: IApiClient, source: WorkspaceCreateInput | WorkspaceView) {
+    if ('workspaceId' in source) {
+      this.view = source
+    } else {
+      this.intent = {
+        input: source,
+        snapshot: { name: intentName(source), phase: 'ready' },
+      }
+    }
+    this.snapshotCache = this.buildSnapshot()
+  }
+
+  /**
+   * Materialize this local Workspace through the Host create seam.
+   * Re-entry shares the in-flight completion; a materialized instance returns undefined.
+   * @returns the Host result, or undefined when this Workspace is already materialized.
+   */
+  materialize(): Promise<RpcResult<{ workspace: WorkspaceView; created: boolean }>> | undefined {
+    if (this.materialization !== null) return this.materialization
+    const intent = this.intent
+    if (intent === undefined) return undefined
+    intent.snapshot = { name: intent.snapshot.name, phase: 'creating' }
+    this.notifier.notifyNow()
+    const completion = this.completeMaterialization(intent).finally(() => {
+      if (this.materialization === completion) this.materialization = null
+    })
+    this.materialization = completion
+    return completion
+  }
+
+  /**
+   * Adopt a Host view without replacing this Workspace object.
+   * An existing materialized identity accepts updates only for the same Workspace id.
+   * @param view - latest Host projection.
+   */
+  adopt(view: WorkspaceView): void {
+    if (this.view !== undefined && this.view.workspaceId !== view.workspaceId) {
+      throw new Error('cannot adopt a different Workspace id')
+    }
+    this.view = view
+    this.intent = undefined
+    this.notifier.markDirty()
+  }
+
+  /**
+   * Subscribe to Workspace snapshot invalidation.
+   * @param listener - snapshot invalidation callback.
+   * @returns unsubscribe function.
+   */
+  subscribe(listener: () => void): () => void {
+    return this.notifier.subscribe(listener)
+  }
+
+  /**
+   * Read the cached Workspace snapshot after flushing pending notifications.
+   * @returns the cached Workspace snapshot.
+   */
+  getSnapshot(): WorkspaceSnapshot {
+    this.notifier.ensureFresh()
+    return this.snapshotCache
+  }
+
+  private async completeMaterialization(
+    intent: WorkspaceIntent,
+  ): Promise<RpcResult<{ workspace: WorkspaceView; created: boolean }>> {
+    let result: RpcResult<{ workspace: WorkspaceView; created: boolean }>
+    try {
+      result = (await this.api.workspace.create(intent.input)).result
+    } catch (error) {
+      result = transportError(error)
+    }
+    if (this.intent !== intent) return result
+    if (result.ok) {
+      this.adopt(result.value.workspace)
+    } else {
+      intent.snapshot = {
+        name: intent.snapshot.name,
+        phase: 'ready',
+        error: `${result.error.code}: ${result.error.message}`,
+      }
+      this.notifier.markDirty()
+    }
+    return result
+  }
+
+  private buildSnapshot(): WorkspaceSnapshot {
+    return { view: this.view, intent: this.intent?.snapshot }
+  }
+}
+
+function intentName(input: WorkspaceCreateInput): string {
+  if ('name' in input) return input.name
+  const trimmed = input.path.replace(/[\\/]+$/, '')
+  return trimmed.split(/[\\/]/).pop() ?? input.path
+}

packages/client/runtime/src/index.ts

@@ -1,11 +1,4 @@
-/**
- * Runtime plugin, node half. The implementation lives entirely in the client
- * half (src/client/ — SlotsService, SessionsService + object layer, and the
- * shell-held ClientLoader under ./loader); consumers import the /client or
- * /loader subpaths. The empty apply exists so the plugin appears in the host
- * Loader (lifecycle governance + dshClient discovery). Contract:
- * api-contracts v3 section 4.
- */
+/** Host loader entry for the browser runtime exported from `./client` and `./loader`. */
 
 /** Host plugin body — no host-side behavior for the runtime plugin. */
 export function apply(_ctx: unknown): void {}