## 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 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
Callbacks from the shared stdio host need to retain each execution's trace context after it yields, without keeping the execution span open until its background cell closes.
## What changed
Capture a W3C trace-context snapshot for each execution and restore it as the parent of tool callback and notification spans. Instrument delegate invocation and its returned future so the context is available on entry and across awaits.
## Testing
Add an integration test with overlapping yielded cells completed in reverse order. Cover sampled, unsampled, and untraced callers, trace isolation, callback and notification parentage, and execution spans finishing while callbacks remain blocked.
GitOrigin-RevId: 57924123d2c2f31bcfaf725688d8bba775235fa0
## What changed
- Add `CodeModeCellTiming` notifications for yielded executions, terminal waits, and unavailable cells, with thread, call, and cell identifiers.
- Measure how long completed results remain buffered before retrieval and carry `result_buffered_for` through the runtime, stdio protocol, and gRPC response metadata. Immediate delivery reports zero; waits without a completed result report no buffering measurement.
- Default missing buffering data to zero for compatibility with older hosts.
## Testing
Extend runtime tests to verify buffering duration with a paused clock and retrieval through termination. Add gRPC conversion tests for nanosecond precision, optional metadata, and the distinction between immediate delivery and no completed result.
GitOrigin-RevId: 60c0c5a3affa69ac3779bf1812fca50f5748af76
Set `CREATE_NO_WINDOW` when launching the code-mode host on Windows so the
child process does not create a console window.
GitOrigin-RevId: ce0d04d7f516d137bcaf5206140aaeaa23334022
## 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
## Why
Code mode wall time should measure the host operation itself, without including
client-side response delays or idle time between requests.
## What changed
- Measure each execute, wait, and terminate request in the code mode host.
- Carry the duration through the stdio and gRPC protocols and use it for
model-visible wall time.
- Emit a structured `codex.code_mode.host_timing` event correlated with the
conversation, turn, tool call, and cell.
## Testing
- Cover successful and failed execution timing, delayed response reads,
repeated waits, termination, and missing cells across stdio and gRPC.
- Verify timing survives protocol serialization and is reflected in app-server
model output and structured telemetry.
GitOrigin-RevId: d24af30c3fc5820521b4beba1f9970714dad6482
## What changed
- Accept only `http://` and `https://` gRPC endpoints for app server
`--code-mode-host` connections.
- Limit the standalone code-mode host to stdio and gRPC listeners.
- Remove the WebSocket session provider, dual-WebSocket negotiation, transport
lanes, and related dependencies and tests.
- Keep coverage for shared and prewarmed gRPC hosts and reject WebSocket host
URLs in CLI parsing tests.
GitOrigin-RevId: 8792604e79ffd54ce776074a4dc3f7d55e63752a
## What changed
Use a 30-second handshake timeout for locally spawned code-mode hosts while
retaining the existing 10-second timeout for WebSocket connections.
GitOrigin-RevId: de1801c062b5c71d4c7b2c33a53b51e0b672445e
## Why
Model-reachable child processes should not inherit Codex launch context.
## What changed
- Treat `OPENAI_FEDERATION_RULE_ID` and `OPENAI_IDENTITY_TOKEN_FILE` as non-inheritable environment variables, with case-insensitive matching.
- Remove them after shell environment policy overrides and before spawning commands across execution, MCP, hooks, Git helpers, and remote helper processes.
## Testing
- Cover inherited and explicitly configured variants, including mixed-case names.
- Verify the variables are absent from real child environments and app-server command and process execution.
GitOrigin-RevId: 2535527893985fef0995617f4c5b2462bea7c136
## Why
Code-mode WebSocket connections are latency-sensitive, so buffering small TCP
writes can delay request and response traffic.
## What changed
- Enable `TCP_NODELAY` on outbound remote-session WebSocket connections.
- Enable `TCP_NODELAY` on sockets accepted by the code-mode host, logging a
warning if the socket option cannot be set.
## Testing
- Add a listener test that connects to the host and verifies the accepted
socket has `TCP_NODELAY` enabled.
GitOrigin-RevId: e51c781c4b47c6a4ae1c32c93cd79768719a68d9
## What changed
- Add `create_session_with_limits` and session-scoped cell execution limits.
- Clamp execute and wait yield times to the session's `max_yield_time_ms`
without terminating the running cell.
- Negotiate support with remote code-mode hosts and include non-default limits
in `session/open`, while keeping unlimited sessions compatible with hosts and
providers that do not support limits.
## Testing
- Cover yield-time clamping, zero-timeout behavior, and isolation between
sessions.
- Cover wire serialization, capability negotiation, unsupported hosts, and
shared process-host execution.
GitOrigin-RevId: 9517321cd605bb87f93eeaa6ba331cc2e346e582
## Why
Code-mode `wait` and `terminate` requests can remain pending when the host
transport stalls.
## What changed
- Add a 60-second transport allowance to the runtime timeout for `wait`, and
apply the same transport deadline to `terminate`.
- Return a model-visible timeout error and invalidate the connection when the
deadline expires, so the next execution reconnects to the host.
## Testing
- Cover queued `wait` and `terminate` requests that exceed their deadlines.
- Verify that a timed-out `wait` reports the error and reconnects on the next
code-mode execution.
GitOrigin-RevId: 5d772e5a6f3793aa8865a1160639b851fd4824fb
## Why
Large nested-tool callbacks can occupy a WebSocket and delay unrelated session
operations on the same code-mode connection.
## What changed
- Negotiate the optional `dual-websocket-v1` capability and pair a second,
token-scoped WebSocket with the control connection.
- Route nested-tool callbacks and their results over the bulk socket while
keeping session operations, notifications, and execution responses on the
control socket. Reject messages sent on the wrong lane.
- Preserve the single-connection transport when the capability is unavailable,
and bound pairing, queued callbacks, and deferred cross-socket messages.
- Defer callbacks that arrive before their execution-started response, and
return delegate errors without disconnecting the connection.
## Testing
Add protocol, transport, driver, and WebSocket integration coverage for
capability negotiation, lane routing, pairing failures, out-of-order messages,
and progress during large concurrent tool results.
GitOrigin-RevId: fa4504653e7cbf3c4ec930ae57aa0a41345bad66
## What changed
- Move the V8 implementation into a dedicated `codex-code-mode-runtime` crate used by `codex-code-mode-host`, removing the embedded runtime fallback from the Codex process.
- Resolve the host executable from the active installation layout and check its availability before selecting tools.
- Fall back to direct tools with a one-time warning when optional code mode is unavailable. Keep `code_mode_only` and `disable_in_process_fallback` configurations fail-closed.
## Testing
- Cover host discovery for standalone and package layouts, including missing hosts and symlinks.
- Verify direct-tool fallback, one-time warnings, and fail-closed code-mode-only behavior.
GitOrigin-RevId: 5aa3c6f1db148b2231fc24089a2ee0e2b00dbddb
## What changed
- Allow `features.code_mode_host` to use a configuration table with
`disable_in_process_fallback`. When enabled, failure to start the standalone
host is returned as tool output instead of falling back to embedded V8.
- Preserve the existing fallback behavior by default and continue accepting the
boolean feature toggle.
- Limit displayed host paths in spawn errors to 512 bytes while retaining the
executable-bearing suffix and valid UTF-8 boundaries.
## Testing
- Cover boolean and table-based feature configuration, fallback-disabled host
failures, and bounded ASCII and UTF-8 error paths.
GitOrigin-RevId: ab3d014e79054c2f8beef9a658915f01cca197b2
## What changed
- Add `--code-mode-host ws://...` and `wss://...` support to `codex app-server`, gated by the `code_mode_host` feature. When omitted, app-server continues to start a local host.
- Share one remote WebSocket connection across the process's threads, using the configured HTTP client's proxy and TLS policy and preserving the existing framed host protocol.
- Reject invalid host URLs, bound WebSocket frame sizes, close connections cleanly, and return an error when a connection exceeds 1,024 pending delegate calls without disconnecting it.
## Testing
- Cover CLI validation, WebSocket protocol execution and shutdown, connection sharing across app-server threads, and delegate-call capacity recovery.
GitOrigin-RevId: 715e82d4d9db1e7e2f91b754a777dcab504e2ae4
## Why
Not every Codex distribution currently includes the
`codex-code-mode-host` companion binary. Enabling the process-host
feature should not make code mode unavailable on those surfaces while
packaging support is being completed.
## What changed
- Fall back to an in-process code-mode session only when spawning the
companion binary returns `io::ErrorKind::NotFound`.
- Keep permission, handshake, timeout, and other host failures visible
instead of silently falling back.
- Store the provider's owned-process/in-process choice as one
enum-backed state so later sessions reuse the fallback decision.
- Preserve the underlying spawn `io::Error` while retaining the host
path in the displayed error.
- Update provider, `CodeModeService`, and end-to-end coverage to verify
successful fallback execution.
## Test plan
- `just test -p codex-code-mode`
- `just test -p codex-core missing_process_host`
## Summary
- add `ProcessOwnedCodeModeSessionProvider` and logical session
generation/rebinding state
- add the supervised child-process connection, reader/writer tasks, and
driver state machine
- make dropped execute/wait/open callers cancellation-safe with explicit
ownership handoff and durable cleanup
- validate cell/delegate lifecycle state and reject invalid protocol
transitions
- add end-to-end stdio coverage for delegates, cancellation, frame
limits, child loss, stale generations, replacement, and long-lived
sessions
## Why
This final stage exposes the process-owned client only after the wire
protocol, host-safe runtime, and standalone host are independently in
place. Transport failure is fail-stop: the client closes local state,
cancels callbacks, reaps the child, and lazily rebuilds a fresh host
generation rather than transactionally recovering the old connection.
## Stack
This is **4 of 4** in the process-owned code-mode session stack.
- Depends on #30111
- Full stack: #30108 → #30110 → #30111 → this PR
## Validation
- `just test -p codex-code-mode -p codex-code-mode-host` — 86 passed
- `just fix -p codex-code-mode`
- `just fix -p codex-code-mode-host`
- `just bazel-lock-update`
- `just bazel-lock-check`
- `bazel test //codex-rs/code-mode:code-mode-unit-tests
//codex-rs/code-mode-host:code-mode-host-unit-tests
//codex-rs/code-mode-host:code-mode-host-stdio-test
//codex-rs/code-mode-protocol:code-mode-protocol-unit-tests` — 4/4
passed
- `just fmt`
pash-openai