## Why
Proxy HTTP 503 responses can contain plain-text or HTML bodies instead of gRPC frames. These responses should reach the existing session admission retry logic as `Unavailable` errors.
## What changed
Strip body data from HTTP 503 responses to `OpenSession`, preserving headers and trailers so tonic can honor an explicit gRPC status or infer `Unavailable` when none is present. Keep this handling scoped to session admission and retain the existing five-attempt retry limit.
## Testing
Extend admission tests to cover bounded retries for plain-text 503 responses, recovery after an HTML 503 response, and an explicit `Internal` gRPC status that prevents retries.
GitOrigin-RevId: c996e13506464e8b65bae06172324bcbadb1f394
## Why
Session-opening failures were returned as strings, preventing callers from inspecting the terminal gRPC admission status directly.
## What changed
- Add `GrpcCodeModeSessionProvider::open_session` returning `GrpcSessionOpenError`, distinguishing admission status codes, admission timeouts, and other setup failures.
- Keep string errors for the existing `CodeModeSessionProvider` trait API.
- Re-export `ProcessOwnedGrpcCodeModeSessionProvider` from `codex-core`.
## Testing
Extend admission tests to assert terminal status codes, cover exhausted `ResourceExhausted` retries, and verify that `DeadlineExceeded` is not retried.
GitOrigin-RevId: 9d7f2e733e12b8bb7def368fa5fc5a09ea2a374e
## Why
Some hosts assign a worker per connection. Idle connection eviction can prevent a quiet session from reaching the worker holding its lease, while retaining a connection after the last session closes unnecessarily keeps that worker allocated.
## What changed
- Disable the HTTP connection pool idle timeout for gRPC code-mode connections.
- Cache URL-based clients weakly and let live sessions own the shared client, releasing their ownership on closure or failure even while the provider remains alive.
- Acquire clients for deferred RPCs only when needed and return the session error if the client has already been released.
## Testing
Add regression tests that verify connection reuse and stored state after 120 seconds of inactivity, and connection closure after the last shared session fails while the provider and session handles remain alive.
GitOrigin-RevId: bd1ff00c4003c03ed173c23dd2ed373ed354ab65
## Why
Shared hosts serve independent chats and their subagents. Larger callback workloads need room for unrelated work and control messages, while gRPC completion bursts can exhaust HTTP/2's small-DATA-frame budget and disconnect shared sessions.
## What changed
- Raise the active-cell limit from 128 to 2,048 and the pending delegate callback limit from 1,024 to 4,096. Expand request and transport queues to leave room for completion bursts and control traffic.
- Negotiate larger callback budgets through the stdio `delegate-capacity-4096` capability and gRPC `max_pending_delegate_calls` field. Preserve the 1,024-callback budget for legacy clients and enforce both session and shared host limits on gRPC.
- Limit concurrent gRPC completion RPCs to 64 across a provider's sessions, allowing queued completions to be canceled without waiting for delivery capacity.
## Testing
Add stdio and gRPC integration tests covering 256 cells and 4,096 callbacks across shared sessions while unrelated work completes. Add tests for callback budget isolation and reuse, rejection of zero capacity, and cancellation of queued completions. Include an ignored resource-intensive test for full host capacity.
GitOrigin-RevId: e85bfa24cc46cc8a735b464d80adf8066a6a6d3a
## Why
Host-side truncation can bound Code Mode output before it crosses the transport, including script errors that would otherwise exceed the frame limit.
## What changed
- Negotiate server-side output truncation for stdio and gRPC sessions, with client-side fallback for older hosts.
- Forward output budgets for execution, waiting, and termination when server-side truncation is selected. Avoid truncating host-formatted output or appending script errors a second time.
- Preserve the negotiated mode across reconnects and reject hosts that cannot maintain it.
## Testing
Add transport and integration coverage for output budgets, oversized script errors, reconnect compatibility, and preservation of output-limit notices with a zero-token budget.
GitOrigin-RevId: 2075101e4845eca64f45491c27a3b326788645c8
## What changed
- Add `GetProcessMetrics` and provider sampling APIs for process ID, start time, cumulative CPU time, and resident memory, exposed through `ThreadManager` without creating a thread or session.
- Distinguish unsupported collection, a locally absent host, and sampling failures. Process-owned providers never start or replace a host when sampling.
- Bound gRPC sampling to one second without retries or explicit connection resets. Run optional collectors on a detached worker with at most one collection in flight, so stalled collection cannot block the HTTP/2 driver or runtime shutdown.
## Testing
Add coverage for snapshots, collector errors and panics, deadlines, overload, and shutdown with a stuck collector. Extend lifecycle tests to check that sampling preserves session state and keepalive behavior without starting or restarting local hosts.
GitOrigin-RevId: eeafe275891d0464636f28a29345a87aed1a12dc
## Why
Automatic gRPC reconnection could spawn a replacement host while dispatching an RPC for an existing session. Host loss must remain visible so recovery can report lost state without replaying execution or completed external effects.
## What changed
- Bind each local host channel to one child process and allow only `OpenSession` to replace a dead host.
- Add caller-owned transport support to `GrpcCodeModeSessionProvider` and map local transport failures to `Unavailable` so initial connection failures use the existing bounded admission retries.
## Testing
Add regression coverage for child exit during initial connection and between channel selection and dispatch, concurrent session recovery, and child reaping after teardown. An integration test kills the host after a command completes and verifies that recovery reports the reset, clears stored state, and leaves the command's external effect unchanged.
Increase the remote MCP stalled-handshake test's initialization timeout and mock response delay to let requests reach the server on loaded CI workers.
GitOrigin-RevId: 4ffd810e4cfcfb7a56e606816aa867bc206a09b6
## 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
## What changed
Add session options for client- or server-owned output truncation and optional `max_output_tokens` budgets for wait and terminate observations. Introduce `TerminateRequest` and update session implementations and callers to use it.
Extend the stdio and gRPC schemas with optional truncation settings and budgets, and define the `bounded-output-v1` capability. Existing sessions retain client-side truncation; providers reject server mode by default. This change defines the contracts without enabling server-side truncation.
## Testing
Extend protocol serialization coverage for `outputTruncation: "server"` while preserving existing wire shapes when optional fields are absent.
GitOrigin-RevId: 22145897ea16d385c5ba9e7549109f7a669fceb4
## Why
Sessions sharing a transport can be admitted to different hosts. Each session needs its own routing token so subsequent RPCs reach the host holding its state.
## What changed
- Capture the optional `x-code-mode-route` metadata from successful `OpenSession` responses and attach it to subsequent session RPCs. Reject tokens longer than 256 bytes and keep new admission attempts free of existing session routes.
- Invalidate a routed session when an `Unavailable` response explicitly sets `x-code-mode-route-lost: true`, allowing a later operation to reopen it without replaying the failed execution. Ordinary `Unavailable` responses preserve the session.
- Allow up to five admission attempts for `Unavailable` and `ResourceExhausted`, with an immediate first retry followed by jittered exponential backoff.
- Order session failure with shutdown so late callback errors cannot cancel an in-flight `CloseSession` RPC.
## Testing
Add regression coverage for independent routing on a shared provider, route-loss recovery without execution replay, preservation of unaffected session state, and callback failures racing shutdown. Extend admission tests to verify the five-attempt limit and recovery tests to distinguish explicit route loss from ordinary unavailability.
GitOrigin-RevId: 5d60ef1afa56beb8c70ba7ab27865128225b0d3d
## Why
Transient admission errors or connection resets can prevent a code-mode session from opening before any execution starts.
## What changed
- Retry `OpenSession` and the initial lease message on `Unavailable` or `ResourceExhausted`, with at most three attempts and 100 ms and 200 ms delays within a single startup deadline.
- Classify HTTP connection and request failures as `Unavailable` so admission can recover from connection resets, while preserving error sources.
- Keep retries limited to initial admission so established executions are never replayed.
## Testing
Add gRPC integration tests covering transient status recovery, the retry limit, immediate failure for non-retryable statuses, and successful session execution after a connection reset.
GitOrigin-RevId: 3b654bcd377a5addf7c3ed58bb1c72a449b2f7f7
## What changed
Add an optional `preempt` signal to `CodeModeSession::execute` and `CodeModeSession::wait` so callers can end an observation early while the cell continues running and remains available for later waits.
Support the signal in the in-process runtime and across both remote transports: `operation/yield` with the negotiated `yield-observation` capability for stdio, and `YieldObservation` for gRPC. Preserve signals received before gRPC observation registration, and retain normal timeout behavior for older hosts that lack support.
## Testing
Add runtime and transport tests covering early execute and wait yields followed by successful cell completion, yields before observation registration, and suppression of yield frames for older stdio hosts.
GitOrigin-RevId: 3f8049d8f0582be6b8f0832cc03f2d974a0b8f18
## Why
A delegate bound at session creation cannot provide different callbacks for cells sharing that session. Each execution needs to retain its own delegate across yields and release it when the cell is cleaned up.
## What changed
- Pass `CodeModeSessionDelegate` to `execute` instead of session creation.
- Route tool calls, notifications, and cell closure callbacks through the execution's delegate in the in-process runtime and the gRPC and stdio transports.
- Retain delegates with pending executions and live cells, releasing them through closure and cancellation cleanup.
## Testing
Add coverage for distinct delegates across yielded cells, gRPC callbacks before cell admission, and delegate release after completion or abandoned execution cleanup. Update transport tests to verify callbacks reach the owning cell's delegate.
GitOrigin-RevId: 7469f52104b993e790a40c65fb800ad02b7fd606
## What changed
- Inject W3C `traceparent` metadata into code-mode session and execution requests.
- Carry each execution's trace context on streamed tool callbacks so callback and nested-tool spans remain connected across the gRPC boundary.
- Preserve the relevant spans when execution, callback, and dispatch work moves into spawned tasks.
GitOrigin-RevId: 6482963cb9b2e2f0ea27f1345bba208b70a80d0b
## What changed
- Reopen a cached code-mode session when its gRPC host stops, while
serializing concurrent reconnection attempts and coordinating shutdown.
- Scope cell IDs to the new host generation so callbacks remain consistent
and stale `wait` or `terminate` requests are rejected.
- Accept both `unix://` and `unix:` endpoints for gRPC hosts on Unix systems.
## Testing
- Cover host restart recovery, concurrent execution after reconnection,
generation-aware callbacks and cell operations, stale cell rejection, and
Unix socket execution.
GitOrigin-RevId: 548e168fdcef7f7d54bd32262e614886bf7bdd32
## What changed
- Build URL-based gRPC code-mode connections with `HttpClientFactory` so they support the application's outbound proxy and custom CA configuration.
- Accept `http` and `https` origins while rejecting endpoints with unsupported schemes, paths, queries, or fragments.
- Preserve custom tonic channel injection and gRPC frame-size limits through the new transport adapter.
GitOrigin-RevId: 142f0b572b3ab0154e8fe860cb304752a9af5784
## What changed
- Subscribe each gRPC code-mode session to nested tool calls and forward tool and notification callbacks to its delegate.
- Complete tool calls through the host while bounding oversized results and errors.
- Track callback ownership and cancellation so completed cells drain notifications, terminated cells cancel them, and shutdown revokes outstanding work.
- Validate callback identifiers, cell ownership, enabled tools, and pending callback limits without serializing independent callbacks or sessions.
## Testing
- Add integration and state tests for callback forwarding, completion ordering, cancellation, malformed callbacks, delegate panics, oversized results, and concurrent work.
GitOrigin-RevId: 005afbb90eea0eb77d746b930a1a96ca6dfcd4e7
## What changed
- Add `GrpcCodeModeSessionProvider` for opening code-mode sessions over HTTP/2 or an existing `tonic` channel.
- Support execution, waiting, termination, per-session limits, cell-closure callbacks, and graceful shutdown over the gRPC protocol.
- Bound transport waits and error messages, validate host identifiers and responses, and clean up abandoned executions and observers.
## Testing
- Add end-to-end TCP tests covering session persistence, cancellation, concurrent waits, shutdown, cell cleanup, and independent yield limits.
- Add unit coverage for protocol conversion, deadlines, and session lifecycle state.
GitOrigin-RevId: d4729ce608ad4b42a99744b07e1f230e46cb24ec
Sean Huang