fix: honor the teardown order on owner unload; make the structured commit unconditional

Adversarial-review findings (own reviewer agent), each verified and pinned:

B1: agents.register() returned a wrapper lambda, so the factory composite's
yield could not identity-nest it — on OWNER unload the unregistration (and
agent/disposed) disposed as a concurrent sibling, firing mid-drain while
the final turn was still closing (pre-existing on master; this branch's
docs re-assert the order, so it must be true). register() now returns the
EXACT cordis effect disposer (the Scope.rawDispose move); the composite
nests it and owner unload runs stop/drain -> unregister -> detach -> scope
like every other path. Regression test pins turn-end before disposed
before detach on owner unload.

B2: the structured two-phase commit could promote a stale stage when a
later capture call REUSED the orphaned stage's call id with a body that
never staged (denied downstream, or invalid args throwing pre-stage). The
runtime's pre-execute listener now clears any stale stage unconditionally
when a new capture call enters the pipeline — only a call's own body can
stage for its commit; the call-id mismatch guard becomes a defensive
second layer. Repro test: blocked capture then same-id invalid call.

C1: an explicit empty toolFilter config now fails at plugin LOAD (the
check is self-contained) instead of killing every delegation at child
setup. C2: Scope.dispose/ScopeHost.dispose @returns state the single-shot
repeat-call semantics honestly.

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

@@ -170,6 +170,40 @@ describe('agent scope lifecycle', () => {
     expect(heard).toEqual(['a1:2'])
   })
 
+  it('owner unload honors the documented teardown order: unregistration AFTER the drain, before detach', async () => {
+    const ctx = await harness()
+    let handle!: ReturnType<typeof ctx.agents.create>
+    const owner = await ctx.plugin(Object.assign((inner: Context) => {
+      handle = inner.agents.create({ agentId: AgentId('o1'), sessionId: SessionId('o1-s'), agentOptions: { model: 'mock' } })
+    }, { inject: ['agents'] }))
+    const { agent } = handle
+
+    const order: string[] = []
+    ctx.on('session/event', (_s, event) => {
+      if (event.type === 'turn/end') order.push('turn-end')
+    })
+    ctx.on('agent/disposed', () => {
+      order.push(`disposed(listed=${ctx.agents.get(AgentId('o1')) !== undefined})`)
+      order.push(`session-still-stored=${ctx.sessions.get(SessionId('o1-s')) !== undefined}`)
+    })
+
+    // Open a turn so the drain has real work: the loop must finish it BEFORE
+    // the registry entry goes away (the agent/disposed contract: "its fiber
+    // and any in-flight turn have been torn down"). Wait for the turn to be
+    // OPEN in the log — a dispose landing in the pre-step window would drop
+    // the queued prompt without ever opening a turn.
+    const turnOpen = new Promise<void>((resolve) => {
+      const off = ctx.on('session/event', (_s, event) => {
+        if (event.type === 'turn/start') { off(); resolve() }
+      })
+    })
+    agent.send(text('work'))
+    await turnOpen
+    await owner.dispose()
+    expect(order).toEqual(['turn-end', 'disposed(listed=false)', 'session-still-stored=true'])
+    expect(ctx.sessions.get(SessionId('o1-s'))).toBeUndefined()
+  })
+
   it('handle.dispose() during owner unload still awaits true quiescence (shared boundary)', async () => {
     const ctx = await harness()
     let handle!: ReturnType<typeof ctx.agents.create>

packages/core/agent/src/index.ts

@@ -208,9 +208,16 @@ export class AgentRegistry extends Service {
    * (calling through `agent.ctx` scopes EFFECTS; dispatch scoping always
    * requires passing the carrier). Returns the disposer.
    * @param agent - the already-constructed agent to record in the store.
-   * @returns the disposer that removes the agent and emits `agent/disposed`.
+   * @returns the EXACT Cordis effect disposer (single-shot; a repeat call
+   *   returns undefined without awaiting an in-flight teardown). Exact
+   *   identity is load-bearing: a composite (generator) effect that owns a
+   *   teardown ORDER — the agent factory's lifecycle chain — must yield THIS
+   *   function so Cordis nests the unregistration at that yield position;
+   *   yielding a wrapper would leave it disposing as a concurrent sibling on
+   *   owner unload, unregistering the agent (and emitting `agent/disposed`)
+   *   while its final turn is still draining.
    */
-  register(agent: Agent): () => void {
+  register(agent: Agent): () => Promise<void> | void {
     const dispose = this.ctx.effect(function* (this: AgentRegistry) {
       if (this.store.has(agent.id)) {
         throw new Error(`agent "${agent.id}" is already registered`)
@@ -242,9 +249,7 @@ export class AgentRegistry extends Service {
       }
       this.ctx.emit(scopeTarget(agent, agent), 'agent/created', agent)
     }.bind(this), 'agents.register()')
-    // ctx.effect's disposer returns Promise<void>; our disposer API is
-    // synchronous fire-and-forget — discard the (always-resolved) promise.
-    return () => void dispose()
+    return dispose
   }
 
   /**

packages/core/scope/src/index.ts

@@ -83,7 +83,12 @@ export interface Scope {
    * returns undefined the second time; this wrapper Promise-normalizes it).
    * After disposal the scoped context is inert — a further registration
    * through it throws Cordis's INACTIVE_EFFECT.
-   * @returns resolves when every registration's disposer has settled.
+   * @returns for the call that initiates teardown: resolves when every
+   *   registration's disposer has settled. A repeat/racing call resolves
+   *   immediately WITHOUT awaiting the in-flight teardown (the underlying
+   *   Cordis disposer is single-shot) — a caller needing a shared quiescence
+   *   boundary across racing disposers keeps its own completion promise (the
+   *   agent factory's pattern).
    */
   dispose(): Promise<void>
 }
@@ -250,7 +255,8 @@ export interface ScopeHost {
   mint(key: ScopeKey): Scope
   /**
    * Dispose the host fiber and with it every scope minted through it.
-   * @returns resolves when all collected disposers have settled.
+   * @returns resolves when all collected disposers have settled (first call;
+   *   a repeat call resolves immediately — single-shot, like Scope.dispose).
    */
   dispose(): Promise<void>
 }