## Why
Extensions can observe thread and turn lifecycle events today, but there
was no single host-owned hook for changes to the effective thread
configuration. That makes features that need to react to model,
permission, or tool-suggest updates either depend on individual mutation
paths or risk going stale after runtime config refreshes.
This adds a typed config-change contributor so extension-owned state can
stay synchronized with the effective thread config while the host
remains responsible for deciding when config changed.
## What Changed
- Added `ConfigContributor<C>` to `codex_extension_api`, with
before/after immutable snapshots of the effective config plus
session/thread extension stores.
- Added registry builder/accessor support through `config_contributor`
and `config_contributors`.
- Emits config-change callbacks after committed updates from session
settings, per-turn setting updates, and `refresh_runtime_config`.
- Builds effective config snapshots only when config contributors are
registered, and suppresses no-op callbacks when the before/after
snapshots are equal.
- Added a core session regression test that verifies contributors
observe both model changes and user-layer runtime config changes,
including access to session and thread extension stores.
## Validation
Added `config_change_contributor_observes_effective_config_changes` in
`codex-rs/core/src/session/tests.rs` to cover the new contributor path.
## Summary
- add a scoped level_id to ExtensionData and expose it through
level_id()
- remove thread_id/turn_id parameters from extension contributor inputs
where the scoped ExtensionData already carries that identity
- move turn-scoped extension data onto TurnContext so token usage and
lifecycle contributors can share the same turn store
## Testing
- cargo check -p codex-extension-api -p codex-core --tests
- cargo test -p codex-extension-api
- cargo test -p codex-guardian
- cargo test -p codex-core --lib
record_token_usage_info_notifies_extension_contributors
- cargo test -p codex-core --lib
submission_loop_channel_close_emits_thread_stop_lifecycle
- cargo test -p codex-core --lib
submission_loop_channel_close_aborts_active_turn_before_thread_stop_lifecycle
- just fix -p codex-extension-api
- just fix -p codex-guardian
- just fix -p codex-core
- just fmt
## Note
- Attempted cargo test -p codex-core; it aborted in
agent::control::tests::spawn_agent_fork_last_n_turns_keeps_only_recent_turns
with the existing stack overflow before the full suite completed.
## Why
Extensions need a stable place to observe token accounting after Codex
folds model-provider usage into the session's cached `TokenUsageInfo`.
Without a contributor hook, extension-owned features that need last-turn
or cumulative token usage have to duplicate session plumbing or infer
state from client-facing `TokenCount` notifications.
## What changed
- Added `TokenUsageContributor` to `codex-extension-api`, passing
session/thread `ExtensionData`, `ThreadId`, turn id, and the current
`TokenUsageInfo`.
- Added registry builder/storage support for token-usage contributors.
- Invoked registered contributors from
`Session::record_token_usage_info` after the session token cache is
updated and before the client `TokenCount` notification is emitted.
## Testing
- Added `record_token_usage_info_notifies_extension_contributors`,
covering cumulative token usage updates and access to both extension
stores.
## Why
Extensions can already contribute prompt, tool, turn-item, and
thread-lifecycle behavior, but there was no explicit host-owned hook for
per-turn setup and cleanup. That makes extension-private turn state
awkward: an extension either has to stash it outside the turn lifecycle
or depend on core runtime objects.
This adds a small turn lifecycle boundary. Extensions receive stable
identifiers plus the existing session, thread, and turn `ExtensionData`
stores, while core keeps owning task scheduling, cancellation, and turn
teardown.
## What Changed
- Added `TurnLifecycleContributor` with `on_turn_start`, `on_turn_stop`,
and `on_turn_abort` callbacks in `codex-rs/ext/extension-api`.
- Added typed `TurnStartInput`, `TurnStopInput`, and `TurnAbortInput`
payloads that expose `thread_id`, `turn_id`, `session_store`,
`thread_store`, and `turn_store`.
- Registered and re-exported turn lifecycle contributors through
`ExtensionRegistry` and `ExtensionRegistryBuilder`.
- Wired `Session` to emit turn start, stop, and abort callbacks from the
existing turn/task lifecycle paths.
- Carried the turn-scoped `ExtensionData` through `RunningTask` and
`RemovedTask` so stop/abort callbacks receive the same turn store
created at turn start.
## Verification
- Not run locally.
## Why
Extensions that need thread-scoped state currently only get a start-time
callback. That is enough for seeding stores, but it leaves the host
without a shared extension seam for later thread rehydrate and flush
work as thread ownership evolves. This PR turns that start-only seam
into a host-owned thread lifecycle contributor contract so
extension-private state can stay behind the extension API instead of
leaking extra orchestration through core.
## What changed
- Replaced `ThreadStartContributor` with `ThreadLifecycleContributor`
and added typed lifecycle inputs for thread start, resume, and stop. The
contract lives in
[`contributors/thread_lifecycle.rs`](d0e9211f70/codex-rs/ext/extension-api/src/contributors/thread_lifecycle.rs (L1-L64)).
- Kept the existing start-time behavior intact by routing session
construction through `on_thread_start`.
- Invoked `on_thread_stop` during session shutdown before thread-scoped
extension state is dropped, while isolating contributor failures behind
warning logs.
- Migrated `git-attribution` and `guardian` onto the lifecycle
registration path.
- Renamed the extension registry plumbing from start-specific
contributors to lifecycle-specific contributors.
## Notes
`on_thread_resume` is introduced at the API boundary here so extensions
can target the final lifecycle shape; host resume dispatch can be wired
where that runtime path is finalized.
## Why
Extension tools were split across two public runtime contracts:
`codex-tool-api` exposed `ToolBundle` plus its own call/spec/error
types, while core native tools used `codex_tools::ToolExecutor`. That
made contributed tool specs and execution behavior easy to drift apart
and added another crate boundary for what should be one executable-tool
seam.
This PR makes `ToolExecutor` the single runtime contract and keeps
extension-specific pinning in `codex-extension-api`.
## Remaining todo
https://github.com/openai/codex/pull/22369/changes#diff-b935ea8245c3ce568a30cff660175fa6390b66b872ae409e1e2e965738250741R5
Either generic `Invocation` or sub-extract the `ToolCall` and clean
`ToolInvocation`
## What changed
- Removed the `codex-tool-api` workspace crate and its dependencies from
core and `codex-extension-api`.
- Made `codex_tools::ToolExecutor` object-safe with `async_trait` so
extension contributors can return a dyn executor.
- Added the extension-facing aliases under
`ext/extension-api/src/contributors/tools.rs`, including
`ExtensionToolExecutor = dyn ToolExecutor<ToolCall, Output =
ExtensionToolOutput>`.
- Changed `ToolContributor::tools` to return extension executors
directly instead of `ToolBundle`s.
- Updated core’s extension tool handler/registry/router path to adapt
those extension executors into the existing native `ToolInvocation`
runtime path.
- Added focused coverage for extension tools being registered,
model-visible, dispatchable, and not replacing built-in tools.
## Verification
- `cargo test -p codex-tools`
- `cargo test -p codex-extension-api`
## Why
`codex-extension-api` needs an approval hook that lets an installed
extension own a rendered approval-review prompt and produce the final
`ReviewDecision`. The prior interceptor stub only exposed a yes/no claim
and did not model the review result itself, which left the host with the
missing half of the control flow.
## What changed
- Replaces `ApprovalInterceptorContributor` with
[`ApprovalReviewContributor`](c49d17531e/codex-rs/ext/extension-api/src/contributors.rs (L43-L55)),
which may claim a rendered prompt and return an async `ReviewDecision`.
- Re-exports the new contributor and future types from `extension-api`.
- Adds registry support through `approval_review_contributor(...)` plus
[`ExtensionRegistry::approval_review(...)`](c49d17531e/codex-rs/ext/extension-api/src/registry.rs (L90-L101)),
which returns the first installed contributor that claims the prompt.
Part 1 of guardian as extension. This bind all the logic to spawn
another agent from an extension and it adds `ThreadId` in the start
thread collaborator
## Why
This is the next narrow step toward moving concrete tool families out of
core. After #22138 introduced `codex-tool-api`, we still needed a real
end-to-end seam that lets an extension own an executable tool definition
once and have core install it without the temporary `extension-api`
wrapper or a dependency on `codex-tools`.
`codex-tool-api` is the small extension-facing execution contract, while
`codex-tools` still has a different job: host-side shared tool metadata
and planning logic that is not “run this contributed tool”, like spec
shaping, namespaces, discovery, code-mode augmentation, and
MCP/dynamic-to-Responses API conversion
## What changed
- Moved the shared leaf tool-spec and JSON Schema types into
`codex-tool-api`, so the executable contract now lives with
[`ToolBundle`](c538758095/codex-rs/tool-api/src/bundle.rs (L19-L70)).
- Replaced the temporary extension-side tool wrapper with direct
`ToolBundle` use in `codex-extension-api`.
- Taught core to collect contributed bundles, include them in spec
planning, register them through
[`ToolRegistryBuilder::register_tool_bundle`](c538758095/codex-rs/core/src/tools/registry.rs (L653-L667)),
and dispatch them through the existing router/runtime path.
- Added focused coverage for contributed tools becoming model-visible
and dispatchable, plus spec-planning coverage for contributed function
and freeform tools.
## Verification
- Added `extension_tool_bundles_are_model_visible_and_dispatchable` in
`core/src/tools/router_tests.rs`.
- Added spec-plan coverage in `core/src/tools/spec_plan_tests.rs` for
contributed extension bundles.
## Related
- Follow-up to #22138
## Why
`codex-core` still owns a growing amount of product-specific behavior.
This PR starts the extraction path by introducing a small, typed
first-party extension seam: features can install the contribution
families they actually own, while the host keeps lifecycle and state
ownership instead of pushing a broad service locator into the API.
See the `examples/` for illustration
## Known limitations
* Tool contract definition will be shared with core
* Fragments must be extracted
* Missing some contributors
