## Why
Suspending a locally controlled agent tree must preserve unfinished turns and child results that arrive during teardown so they remain available after recovery.
## What changed
- Add `ThreadManager::suspend_agent_tree` to stop durable trees, close their writers, and return unfinished root and named V2 child turn IDs plus any pending root wake.
- Persist terminal child results before suspension succeeds, including results queued for evicted parents. Report failed or unconfirmed writes.
- Add `load_suspended_agent` to restore named V2 descendants through their recorded ancestors without starting model turns.
- Allow empty `continue_turn_if_idle` input to wake on saved results, guarded by the preceding turn ID. Keep mail queued until task registration so suspension can preserve it.
## Testing
Add coverage for completion and wake races, child errors, parent writer failures, evicted parents, descendant restoration, repeated suspension after caller cancellation, and ephemeral roots remaining active.
GitOrigin-RevId: 3041791f51bff2555210f6b2d2443f9f05f68330
## What changed
- Initialize item and context-window ID generators per thread, reuse the stored window on resume, and give history reconstruction a separate item generator.
- Recover item ordinals from checkpoint replacement history, guardian history, and retained context without lowering the cursor established by earlier records.
- Stamp compaction resume metadata with the next item ordinal in append order, tracking the cursor in local and in-memory thread stores.
## Testing
Extend the history ordinal test to verify that a checkpoint records the cursor at its position in a batch, excluding later allocations.
GitOrigin-RevId: 7121b747a039dc5477235078702137d1ff74e789
## What changed
- Add `CodexThread::agent_tree_id()` to identify a loaded agent tree. The root and native children share an ID; loading a new tree produces a new ID even when reusing a persisted thread ID.
- Add `EnvironmentManager::remove_environment()` to unregister an environment while preserving existing handles and the default environment ID.
## Testing
Extend tests to check tree IDs across child creation, forks, warm reuse, and cold reloads, and to verify environment removal and re-registration.
GitOrigin-RevId: 43944ed6766374508d9862cd5d333bc4cb67c338
## What changed
Store a shared `ContextWindowIdGenerator` in `LocalAgentRuntime` and pass it into each session. Use it for both initial context window IDs and subsequent window advances, retaining UUID v7 allocation by default.
Make `AutoCompactWindow` accept caller-provided IDs instead of allocating them directly.
## Testing
Update the window boundary test to verify that advancing installs the supplied ID while preserving the first and previous window IDs.
GitOrigin-RevId: a9da4232fe6ab9a53b75e239cb412ceae0fe3216
## What changed
Introduce `ItemIdGenerator` and pass the runtime-owned generator through sessions, model clients, history, hooks, tool outputs, and memory requests. Keep UUIDv7 generation as the default and replace direct calls to `ResponseItemId::new` with the shared callable.
Preserve existing item IDs and backfill missing or empty IDs through the same generator, including forked history before reconstruction and persistence.
## Testing
Extend coverage for UUIDv7 IDs on user messages, agent messages, and additional tools, and assert that forked model context matches the backfilled items persisted to history.
GitOrigin-RevId: 0dd9ccf0f46f0f1005a6acfc740133b03ce82259
## Why
Reloading an evicted sub-agent disabled its rollout tracing, leaving later turns out of the trace. Replacement Code Mode sessions could also reuse cell IDs from earlier sessions.
## What changed
- Reattach reloaded children to the root rollout trace and emit `ThreadResumed` without duplicating `ThreadStarted`.
- Reopen existing threads during replay, preserving their identity and history while clearing stale runtime cell and terminal process mappings.
- Allocate Code Mode cell generations across sessions for both gRPC and stdio hosts to prevent ID reuse after reload.
- Record an aborted trace when session startup fails before the session loop begins.
## Testing
Add regression coverage for child eviction and reload, including a failed reload, continued inference tracing, distinct cell IDs, and preserved mail and follow-up context. Extend replay tests for history preservation and reused runtime handles, and host tests for cell IDs across session replacement and reconnection.
GitOrigin-RevId: 6c146c04b5cda9295afb7d973c0d5474b363a822
## Why
Agent tree shutdown previously returned a generic error without identifying which operation or thread failed, making cleanup failures difficult to diagnose.
## What changed
- Add `AgentTreeShutdown::wait_detailed()` and public report types while preserving the existing `wait()` result and error message.
- Record operation, optional thread ID, and either an abandoned teardown guard or a failed phase with a payload-free error category across session cleanup, child spawn cleanup, and resident eviction.
- Give each tree a correlation ID, log each failure, and retain up to 64 failures with a count of additional failures omitted. Record failures before releasing tree membership so all completed waiters observe the same report.
## Testing
Add unit coverage for aborted and completed teardown, cloned guard context, concurrent and repeated waiters, omitted failure counts, and report formatting without raw error payloads. Extend integration coverage for successful tree shutdown and persistence writer failures, including compatibility with `wait()`.
GitOrigin-RevId: 68784af28b63e875b00a55d78729f0cc5b01ac15
## Why
Spawn failures can share an error kind and message despite different causes, such as execution and residency capacity limits. Telemetry needs enough detail to distinguish these failures without using error messages or correlation IDs as metric labels.
## What changed
- Add `AgentErrorContext` annotations for capacity limits, registry rejections, runtime availability, and spawn stages. Preserve the first annotation so outer stages retain the more precise failure origin.
- Add bounded `detail` and `error_kind` labels to spawn failure metrics, using `unknown` when no context is available.
- Emit spawn failure trace events with these classifications and the call and turn IDs for both multi-agent versions.
## Testing
Add tests for distinct capacity and registry failure contexts, preservation of manager, fork, and shutdown errors, and metric aggregation across different error messages and correlation IDs. Verify that annotations preserve existing error kinds and user-visible messages.
GitOrigin-RevId: 5bbe3d32f6ce408622f38e559fddeab05b8ccb65
## Why
Unread queue-only messages prevented idle agents from unloading, and sending a
message to an evicted agent reloaded its session. Pending mail should not require
an idle recipient to occupy a loaded thread slot.
## What changed
- Retain queue-only mail in an in-memory runtime mailbox when a session unloads.
Queue new messages for locally evicted agents without reloading them or
starting a turn.
- Add `AgentControl::take_mailbox` and `AgentControl::watch_mailbox` so sessions
can consume retained mail and react to host mailbox notifications.
- Preserve message order across eviction, reload, and subsequent follow-ups.
Keep agents with outstanding durable sleep or turn-triggering mail loaded,
and discard retained mail when an agent is removed or its tree shuts down.
## Testing
Add integration coverage for retaining mail across eviction, sending while
unloaded, and ordering messages around a follow-up after reload. Add a host
controller test verifying that mailbox notifications wake `wait_agent` and
that the message is delivered exactly once.
GitOrigin-RevId: 4b55647f9ee9d1aaf3753f0688863bda81617327
## What changed
Expose `ThreadManager::request_agent_tree_shutdown` and an `AgentTreeShutdown::wait` handle. Requests reject new starts in the shared runtime, cancel pending startup, and signal every session in that tree, including delegates outside the thread registry. Waiting covers admitted operations and session teardown, and reports cleanup or persistence writer failures. Other root trees remain unaffected; registry removal and persistence handoff remain caller responsibilities.
Retain tree membership through startup, cancelled spawn cleanup, residency eviction, and completion watchers. Release persistence resources before returning startup failures, and stop completion watchers during tree shutdown without reporting shutdown as a child result.
## Testing
Add coverage for tree isolation, children removed from the registry, delegate teardown, cancellation during required MCP initialization, aborted teardown, persistence writer failures, and successful retry after a failed resume releases its writer.
GitOrigin-RevId: a109e25adf23d20baf7595891099947050c6b6b5
## What changed
- Add `ThreadManager::with_agent_control_factory` to select a host-owned controller asynchronously using the final thread ID for new and cold-resumed threads. Keep local control as the default, reuse live controllers on warm resume, and preserve parent controllers for internal sessions.
- Fail startup on factory errors or when a provided controller's identity does not match the session identity.
- Defer root service-tier updates to host controllers until thread registration succeeds, preventing failed starts from changing settings on a shared controller.
GitOrigin-RevId: 095afbecfee5d47329038d2a97d0cc0081f181df
## What changed
- Store `Arc<dyn AgentControl>` in session services and route agent tools, turn admission, usage accounting, completion notifications, and shared settings through the trait.
- Add `AgentControlInit` so delegated and guardian sessions inherit the parent's controller and local runtime.
- Move local registry and context helpers to `LocalAgentRuntime`, keep resume, close, inspection, and status subscriptions on the local controller, and simplify synchronous and infallible trait methods.
GitOrigin-RevId: ad3f213eb483ac524bde56d769f20a78f20989a0
## What changed
Extract `LocalAgentRuntime` from `LocalAgentControl` to hold the shared registry, residency state, execution limiter, rollout budget, service tier, instruction provider, and thread-manager bindings. Keep session identity on the controller handle.
Store the runtime in `SessionServices` and use it to bind controllers for child startup, resume, delegation, and guardian reviews. Route ownership checks and residency handling through the shared runtime, preserving registry identity across handles. Update existing test fixtures to keep the controller and runtime paired.
GitOrigin-RevId: 846094657cbdf736da3149f0a1c96b4e01423dfe
Bryan Ashley