Merge branch 'codex/simp-ui-identity-residue' into codex/simp-hide-concrete-agent-loop

# Conflicts:
#	packages/core/agent-loop/README.md

packages/core/agent-loop/README.md

@@ -14,7 +14,7 @@ The caller fiber and the AgentLoop provider are co-owners. `AgentFactory.createA
 
 Each agent and its session share one caller-chosen `SessionId`, assumed globally unique; accidental UUID collisions are outside the supported model. Two concurrent operations with the same id may both prepare, but the final `enter()` calls arbitrate publication and every loser rolls its private resources back. Each detach is bound to the exact entered object, so a stale disposer cannot remove a later same-id replacement. A detach requested during a synchronous creation notification waits for that dispatch to unwind, preserving created/disposed pairing. Teardown runs stop and drain (including outstanding idle-injection flushes) → detach agent → detach session → unwind scope; the id becomes reusable at detach even if private scope cleanup is still finishing. Ordinary non-vetoing `agent/*` notifications go through `agentEvents(ctx, agent)`, per-step assembly goes through `assembleContextFor(agent)`, and turn-end durability checkpoints go through `ctx.sessions.flush(session)`.
 
-- `ctx.agentLoop.create(id: SessionId, options?: AgentOptions, meta?: { cwd?: string }): Agent` — synchronous no-setup create under the exact shared agent/session id, disposed with the calling fiber. Declarative config treats `agents[].id` as a stable label and normally mints `${label}-session-<uuid>` before calling this boundary; an app may instead supply an exact fresh `sessionId` when another coupled component must bind to it. `resumeSessionId` loads and registers the exact persisted id and is mutually exclusive with `sessionId`. This keeps default fresh restarts collision-free without retaining a second live routing identity.
+- `ctx.agentLoop.create(id: SessionId, options?: AgentOptions, meta?: { cwd?: string }): Agent` — synchronous no-setup create under the exact shared agent/session id, disposed with the calling fiber. Declarative config treats `agents[].id` as a stable label and normally mints `${label}-session-<uuid>` before calling this boundary. An app may instead supply a stable exact `sessionId`: first use creates it, while a remount with persistence already present resumes its materialized history. `resumeSessionId` requires and loads an existing persisted id and is mutually exclusive with `sessionId`. This keeps default fresh restarts collision-free without retaining a second live routing identity.
 
 `AgentLoop` also implements the `AgentFactory` seam and registers itself via `ctx.agents.setFactory(this)`, so plugins create/resume agents through `ctx.agents` (the interface):
 
@@ -33,7 +33,7 @@ The config-driven `ctx.agentLoop.create()` path keeps its agent owned by the loo
 interface Config {
   agents: Array<{
     id: string                 // required stable label; prefixes fresh combined ids
-    sessionId?: string         // optional exact identity for a fresh session
+    sessionId?: string         // optional exact resume-or-create identity
     model?: string
     resumeSessionId?: string   // load this persisted session instead of creating one
     cwd?: string               // optional workspace cwd for the fresh session
@@ -41,7 +41,7 @@ interface Config {
 }
 ```
 
-Agents listed in config are auto-created at startup. `cwd` and optional `sessionId` apply only to fresh config-created sessions; `resumeSessionId` keeps the persisted session header. Config agents have no per-agent persona field: they use `dsh-system-prompt`'s deployment default, while programmatic factory callers can register an agent-scoped `deployment:persona` shadow in `setup`. The plugin registers the built-in `model`/`cwd` prompt variables on `ctx.systemPrompt`, resolved per step from `assembleContextFor(agent)` — the helper couples the typed agent with its matching scope selector. These are runtime facts of the agents THIS loop drives, unlike the `harness:identity` and default `deployment:persona` sections, which live on `dsh-system-prompt` so they survive a swapped loop plugin.
+Agents listed in config are auto-created at startup. `cwd` seeds a fresh config-created session; a materialized exact `sessionId` remount and an explicit `resumeSessionId` keep the persisted session header. Config agents have no per-agent persona field: they use `dsh-system-prompt`'s deployment default, while programmatic factory callers can register an agent-scoped `deployment:persona` shadow in `setup`. The plugin registers the built-in `model`/`cwd` prompt variables on `ctx.systemPrompt`, resolved per step from `assembleContextFor(agent)` — the helper couples the typed agent with its matching scope selector. These are runtime facts of the agents THIS loop drives, unlike the `harness:identity` and default `deployment:persona` sections, which live on `dsh-system-prompt` so they survive a swapped loop plugin.
 
 ### Internal concrete driver
 

packages/core/agent-loop/src/index.ts

@@ -325,7 +325,7 @@ export interface Config {
   agents: (AgentOptions & {
     /** Stable config label used in logs and as the fresh combined-id prefix. */
     id: string
-    /** Optional exact identity for a fresh session; absent lets the loop mint one from the label. */
+    /** Optional stable identity; remounts resume its materialized history, while first use creates it fresh. */
     sessionId?: SessionId
     /** Optional workspace for a fresh session. */
     cwd?: string
@@ -363,8 +363,17 @@ export class AgentLoop extends Service implements AgentFactory {
     ctx.systemPrompt.variable('cwd', context => context.agent?.session.header.cwd)
 
     for (const { id, sessionId, cwd, resumeSessionId, ...options } of config.agents) {
+      const meta = cwd === undefined ? {} : { cwd }
       if (resumeSessionId === undefined || resumeSessionId === '') {
-        this.create(sessionId ?? SessionId(`${id}-session-${randomUUID()}`), options, cwd === undefined ? {} : { cwd })
+        const configuredId = sessionId ?? SessionId(`${id}-session-${randomUUID()}`)
+        const persistence = sessionId === undefined ? undefined : ctx.get('sessionPersistence')
+        if (persistence === undefined) {
+          this.create(configuredId, options, meta)
+        } else {
+          void this.restoreOrCreateConfigured(ctx, persistence, configuredId, options, meta).catch((error: unknown) => {
+            ctx.logger.warn(`agent "${id}": config-driven restore of "${configuredId}" failed: ${String(error)}`)
+          })
+        }
         continue
       }
       if (sessionId !== undefined) {
@@ -384,6 +393,22 @@ export class AgentLoop extends Service implements AgentFactory {
     }
   }
 
+  /** Restore a materialized exact config identity on remount, or create it on first use. */
+  private async restoreOrCreateConfigured(
+    ownerCtx: Context,
+    persistence: SessionPersistence,
+    sessionId: SessionId,
+    agentOptions: AgentOptions,
+    meta: Pick<SessionHeader, 'cwd'>,
+  ): Promise<void> {
+    const exists = (await persistence.list()).some(header => header.id === sessionId)
+    if (exists) {
+      await this.resumeWith(ownerCtx, persistence, { resumeSessionId: sessionId, agentOptions })
+      return
+    }
+    this.create(sessionId, agentOptions, meta)
+  }
+
   /**
    * Create an agent and session under one caller-supplied identity, owned by
    * the accessing fiber. Constructor-driven config calls mint a fresh combined

packages/core/agent-loop/tests/config-session-id.spec.ts

@@ -55,6 +55,43 @@ describe('config-driven session id', () => {
     await conflicting.fiber.dispose()
   })
 
+  it('restores a materialized exact id across an AgentLoop-only reload', async () => {
+    const root = await mkdtemp(join(tmpdir(), 'dsh-cfg-exact-reload-'))
+    dirs.push(root)
+    const ctx = await makeCoreContext()
+    await ctx.plugin(SessionPersistenceJsonl, { root })
+    ctx.llm.registerAdapter(['mock'], new MockAdapter([textResponse('first'), textResponse('second')]))
+    const config = { agents: [{ id: 'main', sessionId: SessionId('stdio-exact-reload'), model: 'mock' }] }
+
+    const firstLoop = await ctx.plugin(AgentLoop, config)
+    let first: Agent | undefined
+    for (let i = 0; i < 50 && first === undefined; i++) {
+      await new Promise(resolve => setTimeout(resolve, 5))
+      first = ctx.agents.get(SessionId('stdio-exact-reload'))
+    }
+    expect(first).toBeDefined()
+    first!.send([{ type: 'text', text: 'remember me' }], { source: { kind: 'user' } })
+    await waitForIdle(ctx, first!)
+    await firstLoop.dispose()
+
+    const secondLoop = await ctx.plugin(AgentLoop, config)
+    let second: Agent | undefined
+    for (let i = 0; i < 50 && second === undefined; i++) {
+      await new Promise(resolve => setTimeout(resolve, 5))
+      second = ctx.agents.get(SessionId('stdio-exact-reload'))
+    }
+    expect(second).toBeDefined()
+    expect(JSON.stringify(second!.session.deriveMessages())).toContain('remember me')
+    second!.send([{ type: 'text', text: 'continue' }], { source: { kind: 'user' } })
+    await waitForIdle(ctx, second!)
+    await ctx.sessions.flush(second!.session)
+    const loaded = await ctx.sessionPersistence.load(SessionId('stdio-exact-reload'))
+    expect(loaded.events.filter(event => event.type === 'turn/start')).toHaveLength(2)
+
+    await secondLoop.dispose()
+    await ctx.fiber.dispose()
+  })
+
   it('identity-nests the deferred resume fiber under its labeled owner effect', async () => {
     const ctx = new Context()
     await ctx.plugin(LlmService)