## Why
`parent_turn_id` identifies the immediate caller of a nested request, but not the
top-level turn that initiated a multi-level chain of work.
## What changed
- Add `root_turn_id` to turn state, submissions, and Responses API metadata.
- Propagate the root through spawned agents, delegated work, review sessions, and
turn-triggering inter-agent messages.
- Omit the root when background work has no user turn or combined input makes the
root ambiguous.
## Testing
Added coverage for nested agent resumes, reviews, mailbox delivery, steered input,
and reserved metadata handling.
GitOrigin-RevId: 60057db2ee81f4efefa946a9f63c74ff98b93929
## What changed
- Add `auto_review_enabled` to serialized turn metadata for regular and review turns.
- Derive the value from approval-policy routing and reserve the metadata key so client-provided metadata cannot override it.
## Testing
- Cover enabled metadata, reserved-key handling, Guardian review requests, and updated compaction request snapshots.
GitOrigin-RevId: 52773e2bf7d4be251f8466332de9f9c9869dd084
## What changed
- Add `responses_api_metadata` for product-owned key/value metadata included in
every Responses API turn metadata payload, including parent and subagent
requests.
- Limit the map to 16 entries, ASCII identifier keys of at most 64 bytes, and
values of at most 128 bytes. Reject reserved Codex metadata keys and ignore
this setting in project-local configuration.
- Give configured product metadata precedence over app-server client metadata
while keeping it out of metadata sent to external MCP servers.
## Testing
- Cover reserved-key validation, metadata precedence, MCP isolation, and
propagation to parent and subagent Responses API requests.
GitOrigin-RevId: a7be798294fde25145ab375a468321bb4e4a49f1
## What changed
- Add the effective permission profile as `sandbox_mode` in turn metadata for regular, prewarm, compaction, and detached memory requests.
- Reserve `sandbox_mode` so client-provided metadata cannot override the computed value.
## Testing
- Cover metadata headers and request bodies for read-only and danger-full-access modes.
GitOrigin-RevId: 13c690cc99bc2691023f281ca527af049bb1286f
## What changed
- Stop adding `code_mode_tool_names` to Responses Lite turn metadata.
- Keep `code_mode_tool_names` reserved so client metadata cannot reintroduce the removed, unbounded inventory.
- Use the opt-in `tool_namespaces_info` metadata, including each function's `code_mode_name`, when authoritative tool details are requested.
## Testing
- Update Responses Lite and code-mode tests to verify the opt-in namespace metadata and normalized code-mode names.
GitOrigin-RevId: cbfb9af984de71c7cc175d0cd47ae799a5275309
## What changed
- Add opt-in `tool_namespaces_info` metadata for Responses Lite turns when
`tool_registry.turn_metadata_includes_tool_info` is enabled.
- Describe each model-visible function's namespace, direct and deferred
exposure, Code Mode name, and harness or MCP ownership.
- Reject visible namespaces shared by different owners when strict collision
checking and tool inventory metadata are enabled.
- Keep tool inventories out of compatibility headers and metadata sent to MCP
servers.
## Testing
- Cover opt-in behavior, MCP exposure details, namespace ownership collisions,
reserved metadata handling, and Responses Lite request serialization.
GitOrigin-RevId: 6a6965d2ba98e29444fdfbb4ccec6aafcf0391e6
## What changed
- Add an `x-codex-routing-hint` header containing the request model and, when selected, the service tier.
- Send the hint on Responses HTTP requests, remote compaction requests, and WebSocket handshakes, including prewarm connections.
- Limit the header to Codex-backend authentication with the OpenAI provider, omitting it for API-key and provider-specific credential paths.
## Testing
- Cover routing hints for HTTP, remote compaction, WebSocket streaming, and tiered prewarming, along with the credential paths where the header must be absent.
GitOrigin-RevId: d8d415d7fadddecf9a132d05920b856a35ac9960
## What changed
- Propagate the initiating turn ID through agent spawns, follow-up tasks, reviews, and delegated Codex sessions.
- Add `parent_turn_id` to Responses client and turn metadata while keeping it out of external MCP metadata.
- Preserve parent-turn provenance across queued agent messages when their triggering parent is unambiguous.
## Testing
- Cover spawned, resumed, nested, reviewed, delegated, and WebSocket request metadata.
- Verify queued messages do not claim ambiguous or queue-only parent turns.
GitOrigin-RevId: 481fdebbe7df2031880fe259509273cce50b20a8
## Why
The Code Mode tool-name mapping is unbounded and can make HTTP and WebSocket
headers grow without limit.
## What changed
Omit `code_mode_tool_names` from the direct `x-codex-turn-metadata`
compatibility header while retaining it in the canonical
`client_metadata["x-codex-turn-metadata"]` payload.
GitOrigin-RevId: 494a30b6846e32ab44eb79b08dfec63360f563a7
## What changed
- Add `code_mode_tool_names` to Responses Lite turn metadata, mapping each normalized code-mode identifier to its structured `ToolName`.
- Reserve the metadata key against client overrides and omit it from metadata exposed to external MCP servers.
- Keep non-Lite requests and the legacy top-level client metadata unchanged.
## Testing
- Cover HTTP and WebSocket Responses Lite requests, including switching from a non-Lite model.
- Verify reserved-key handling and external MCP metadata filtering.
GitOrigin-RevId: b678afba13d57a91e26f5895aa37238fbb4cb276
## Why
Pre-sampling compaction intentionally uses the previous turn's model
when the compaction compatibility hash changes or when switching to a
model with a smaller context window. This keeps compaction aligned with
the settings that produced the history, but it can block the next turn
when a resumed ChatGPT thread still references a model slug that has
since been retired. The Codex backend rejects that compaction request
before the user's currently selected model gets a chance to sample.
This PR lets those threads recover without changing previous-model
compaction behavior for API-key authentication or custom providers. It
is stacked on #31316, which is a behavior-preserving extraction of the
individual remote compaction attempts; this PR contains the fallback
behavior.
## What changed
- For automatic previous-model compaction, capture the selected model's
request context when using ChatGPT authentication with the OpenAI
provider and the selected model differs from the previous model.
- If the previous-model attempt returns an `InvalidRequest`, retry
compaction once with the selected model for both `/responses/compact`
and Responses Compaction V2.
- Complete history processing, lifecycle events, and token accounting
with the context of the model that successfully compacted the thread.
- If the fallback also fails, return the original previous-model error
so the retry does not change the user-visible failure.
- Record fallback attempts with reason, implementation, and outcome
telemetry.
- Leave API-key authentication, custom providers, same-model turns, and
non-`InvalidRequest` failures on their existing paths.
## Testing
- `just test -p codex-core -E 'test(pre_sampling_compact) |
test(model_unavailable_error)'` (10 tests)
- Added integration coverage for a resumed thread whose model was
renamed, a model downshift using Responses Compaction V2, and API-key
authentication with a custom provider.
## Description
Restore `thread_source` in `x-codex-turn-metadata`.
Inadvertently removed `thread_source` from `x-codex-turn-metadata` in
https://github.com/openai/codex/pull/27122 - didn't realize it was a
top-level thread app-server API field, not passed in
`responsesapi_client_metadata`.
This also reserves the key so `responsesapi_client_metadata` cannot
override it.
## What
Introduce a `CodexResponsesMetadata` struct that defines all the core
metadata we send to Responses API. Example fields are `thread_id`,
`turn_id`, `window_id`, etc.
Going forward, `client_metadata["x-codex-turn-metadata"]` will be the
canonical way Codex sends metadata to Responses API across both HTTP and
websocket transports.
For now, we continue to emit the existing top-level HTTP headers and
top-level `client_metadata` fields from the same
`CodexResponsesMetadata` struct for compatibility reasons.
Also, app-server clients who specify additional
`responsesapi_client_metadata` via `turn/start` and `turn/steer` will
have those fields merged into
`client_metadata["x-codex-turn-metadata"]`, but cannot override the
reserved fields that core uses (i.e. the fields in
`CodexResponsesMetadata`).
## Why
Responses API request instrumentation is the source of truth for
downstream Codex analytics that join requests by Codex IDs such as
session, thread, turn, and context window. Before this change, those
values were assembled through several request-specific paths: HTTP
request bodies, websocket handshake headers, websocket `response.create`
payloads, compaction requests, and the rich `x-codex-turn-metadata`
envelope all had their own wiring.
That made metadata propagation easy to drift across API-key/direct
Responses API requests, ChatGPT-auth/proxied requests, websocket
requests, and compaction requests. It also made additions like
`window_id` error-prone because a field could be added to one transport
projection but missed in another.
## What changed
- Added `CodexResponsesMetadata` as the core-owned snapshot for Codex
metadata sent to ResponsesAPI.
- Render `client_metadata["x-codex-turn-metadata"]`, flat
`client_metadata` projections, and direct compatibility headers from
that same snapshot.
- Include the known Codex-owned fields in the turn metadata blob,
including installation/session/thread/turn/window IDs, request kind,
lineage, sandbox/workspace metadata, timing, and compaction details.
- Treat app-server `responsesapi_client_metadata` as enrichment for the
Codex turn metadata blob while preventing those extras from overriding
Codex-owned fields.
- Use the same metadata path for normal turns, websocket prewarm, local
compaction, remote v1 compaction, and remote v2 compaction.
- Keep websocket connection-only preconnect metadata separate so
handshakes carry compatibility identity headers without inventing a fake
turn metadata blob.
## Verification
- `cargo check -p codex-core`
- `just fix -p codex-core`
Eddie Chen