refactor(core): simplify scoped agent lifecycles

packages/core/agent-loop/README.md

@@ -8,16 +8,18 @@ This is the only package in the harness that contains concrete loop logic. Every
 
 ### Public API
 
-Lifecycle (scoped and dual-owned): programmatic creation and resume snapshot caller-owned identity/configuration data, obtain registry/store-owned capabilities for both unpublished IDs, mint `agent.ctx`, and install the ordered teardown skeleton before awaiting optional `setup`. `AgentFactory.createAgent(ownerCtx, options)` and `resume(ownerCtx, options)` receive caller ownership explicitly; the trace-bound `AgentLoop` receiver still supplies the dependency origin, so a caller that injects only `agents` can create an agent whose scope reaches the loop's `sessions`/`llm`/`tools`/`systemPrompt` surface. The caller owns cancellation and the returned handle, while AgentLoop remains a structural second owner because the live driver depends on that service surface: unloading the provider aborts pending load/setup, tears down live programmatic agents, and awaits the same quiescence and ID-release boundary before its dependencies disappear.
+Creation and resume are one rollback-covered transaction: construct a private session, concrete agent, and scoped context; await optional setup; enter both registries; announce `session/created` then `agent/created`; emit `agent/session-start`; and only then start the driver. Setup receives the full scoped `Context` as trusted same-process composition code and must not drive the unpublished agent. Ordinary typed identity and option inputs are borrowed under their readonly contract, while seed events and session metadata are validated and snapshotted because they cross the durable session boundary. An optional `AbortSignal` cancels only load/setup/publication and is detached before the returned handle becomes visible.
 
-The complete create transaction is factory-tracked before ID reservation/session validation, and both a factory placeholder and lifecycle-long caller sentinel exist before scope minting can reenter plugin lifecycle notifications. The caller sentinel adopts the exact reservation effects and always follows the memoized lifecycle boundary, including handle-first teardown followed by caller unload. Resume adds a load sentinel before persistence I/O; it waits for load settlement until `startOwned` synchronously returns a lifecycle/rollback disposer, then follows that disposer without a handoff gap. The ID capabilities reject competing `register`/`enter`/`prepare`/`create` calls and remain held through scope quiescence. A create hands one-read raw seed and metadata references synchronously to the session boundary, which rejects exotic shells and materializes accepted values in a single recursive pass; pre-cloning either value could incorrectly sanitize prototypes. Resume captures each loaded metadata field once. After setup resolves, the factory checks caller and provider liveness after constructing both registry entries but before the first announcement, after `session/created`, after `agent/created`, and again after `agent/session-start` before starting the driver, so synchronous getter- or listener-triggered teardown wins. A publication-wide barrier flips lifecycle liveness immediately but keeps both entries and `agent.ctx` intact until the current synchronous notification phase unwinds; only then does rollback revoke them. Registry/store entries claim IDs across caller-code commit windows, detach exact objects only, and reuse stable carriers for paired edges. Load/setup rejection or owner unload before announcement emits no creation edge; if teardown begins inside a creation or session-start listener, the already-started notifications are paired during rollback and no live or drivable publication survives. Teardown runs stop/drain (including outstanding idle-injection flushes) → unregister → detach session → unwind scope → release reservations. After quiescence, the caller sentinel and any resume-load sentinel disarm and remove their owner-fiber effects so a long-lived caller does not retain the completed agent and scope. Ordinary non-vetoing `agent/*` notifications go through `agentEvents(ctx, agent)`; the registry's paired disposal edge applies the same failure containment through its captured carrier. Per-step assembly goes through `assembleContextFor(agent)`, and the turn-end durability checkpoint goes through `ctx.sessions.flush(session)`.
+The caller fiber and the AgentLoop provider are co-owners. `AgentFactory.createAgent(ownerCtx, options)` and `resume(ownerCtx, options)` receive caller ownership explicitly, while the factory keeps its own dependency context for `sessions`/`llm`/`tools`/`systemPrompt`; this lets a caller inject only `agents` without shrinking the new agent's service surface. Caller unload, handle disposal, or provider unload converge on one memoized quiescence boundary. Provider shutdown waits both resource teardown and the public create/resume wrapper that observed deactivation, so no continuation can publish after dependencies disappear.
+
+IDs are caller-chosen and assumed globally unique; accidental UUID collisions are outside the supported model. Two concurrent operations with the same agent or session 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; IDs become 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: string, options?: AgentOptions, meta?: { cwd?: string }): ReactLoopAgent` — synchronous no-setup create, used directly by programs and by `cordis.yml`-configured agents. It creates a fresh per-run session id `${id}-session-<uuid>` with optional metadata; the uuid avoids colliding with a prior durable log. Each call is a new session (a deliberate demo simplification — a real resume-or-create policy is a TODO). Disposed with the calling fiber.
 
 `AgentLoop` also implements the `AgentFactory` seam and registers itself via `ctx.agents.setFactory(this)`, so plugins create/resume agents through `ctx.agents` (the interface):
 
-- `ctx.agents.create({ agentId, sessionId, meta?, seed?, agentOptions?, setup? }): Promise<AgentHandle>` — programmatic create on a caller-supplied `sessionId`, NOT `${id}-session`. It awaits the unpublished setup transaction before returning; `meta` carries cwd/lineage/seed-boundary metadata and `seed` reconstructs a forked child prefix after the session boundary validates and detaches each raw value in one pass. The resolved [`AgentHandle`](../agent/README.md) owns exact teardown.
-- `ctx.agents.resume({ agentId, resumeSessionId, agentOptions?, setup? }): Promise<AgentHandle>` — load a persisted session via `ctx.sessionPersistence` ([session persistence](../../../docs/rfc/implemented/architecture/2026-06-14-session-persistence.md)), reconstruct its history, then await setup against a fresh unpublished agent scope before rollback-covered publication. The live session id is the resumed id; turn numbering and derived history continue from the loaded log. Requires a session-persistence backend (NOT hard-injected — non-persistent demos still work; `resume` rejects with a clear error when persistence is absent). Returns an `AgentHandle`.
+- `ctx.agents.create({ agentId, sessionId, meta?, seed?, agentOptions?, setup?, signal? }): Promise<AgentHandle>` — programmatic create on a caller-supplied `sessionId`, NOT `${id}-session`. It awaits the unpublished setup transaction before returning; `meta` carries cwd/lineage/seed-boundary metadata and `seed` reconstructs a forked child prefix after the session boundary validates and snapshots the durable values. `signal` applies only until this promise settles. The resolved [`AgentHandle`](../agent/README.md) owns exact teardown.
+- `ctx.agents.resume({ agentId, resumeSessionId, agentOptions?, setup?, signal? }): Promise<AgentHandle>` — load a persisted session via `ctx.sessionPersistence` ([session persistence](../../../docs/rfc/implemented/architecture/2026-06-14-session-persistence.md)), reconstruct its history, then await setup against a fresh unpublished agent scope before rollback-covered publication. The live session id is the resumed id; turn numbering and derived history continue from the loaded log. Requires a session-persistence backend (NOT hard-injected — non-persistent demos still work; `resume` rejects with a clear error when persistence is absent). `signal` is creation-only. Returns an `AgentHandle`.
 
 The config-driven `ctx.agentLoop.create()` path keeps its agent owned by the loop fiber (it discards the handle). For a programmatic agent, the handle holder is the only consumer-facing teardown capability; AgentLoop provider unload is the independent structural teardown edge, not another handle exposed to application code.
 
@@ -44,7 +46,7 @@ Agents listed in config are auto-created at startup. `cwd` applies only to fresh
 
 - `ReactLoopAgent` — the concrete `Agent` implementation. Its inbox is a JavaScript native-private field, and one prepared session can be claimed by only one concrete driver. Everything observable happens through session events and the `agent/*` event taxonomy.
 
-`Inbox`, `runLoop`, and the instance-bound enable/start controls are package-internal. The package root does not export them, and the package exports map exposes no `./src/*` escape hatch; lifecycle owners create agents through `ctx.agents` rather than constructing or starting the driver internals. `ReactLoopAgent.send()` and running `steer()` materialize content plus resolved source once as detached, deeply frozen lossless JSON, then share that accepted record between `agent/queued` and the inbox; malformed data throws before either boundary.
+`Inbox`, `runLoop`, and the instance-bound publication/start controls are package-internal. The package root does not export them, and the package exports map exposes no `./src/*` escape hatch; lifecycle owners create agents through `ctx.agents` rather than constructing or starting the driver internals. `ReactLoopAgent.send()` and running `steer()` materialize content plus resolved source once as detached, deeply frozen lossless JSON, then share that accepted record between `agent/queued` and the inbox; malformed data throws before either boundary.
 
 ### Loop lifecycle (`loop.ts`)
 
@@ -91,7 +93,7 @@ forever:
   idle unless more queued
 ```
 
-Error containment: a throwing plugin ends the **turn**, never the loop. A malformed or throwing `agent/turn-stop` policy likewise fails the turn closed. A successful terminal stop stays authoritative through `turn/end` and `session/flush`, preventing their listeners from resurrecting steering through the late fallback. Dispose mid-turn emits `agent/status('disposed')` and ends with reason `disposed`. A step that hits the model's output-token ceiling makes the turn end `max-tokens` (the rule: any `max-tokens` step in the turn surfaces as `max-tokens`; `disposed`/`aborted`/`error` still take precedence) — distinct from a clean `completed` stop.
+Error containment: a throwing plugin ends the **turn**, never the loop. A throwing `agent/turn-stop` policy likewise fails the turn closed. A successful terminal stop stays authoritative through `turn/end` and `session/flush`, preventing their listeners from resurrecting steering through the late fallback. Dispose mid-turn emits `agent/status('disposed')` and ends with reason `disposed`. A step that hits the model's output-token ceiling makes the turn end `max-tokens` (the rule: any `max-tokens` step in the turn surfaces as `max-tokens`; `disposed`/`aborted`/`error` still take precedence) — distinct from a clean `completed` stop.
 
 Cancellation: `agent.cancel()` is the single public stop primitive — it clears the queued + steering FIFOs, aborts the in-flight step, and drives a turn-scoped marker the driver checks at every point a turn could start or continue (right after the idle wait, after the `running` flip, before each step, and at the continuation gate) so a turn about to start is dropped. A cancelled turn ends `aborted`; a queued-but-not-started prompt never runs and cannot be batched into the cancelled turn. The marker is reset once per loop iteration, so a cancel governs exactly one turn and never leaks onto a later prompt. (The loop still aborts its own per-step `AbortController` directly on disposal and from `cancel()`; that controller is loop-internal, not a public verb.)