## Why
Client-created response items enter history without IDs, so their
identity is lost across rollout persistence and resume. IDs should be
assigned once at the history-recording boundary, while IDs returned by
the server must remain unchanged.
The Responses API validates item IDs using type-specific prefixes.
Locally generated IDs therefore use the matching prefix plus a
hyphenated UUIDv7, keeping them valid while distinguishable from
server-generated IDs. Because this changes persisted history and
provider request shapes, the behavior is opt-in behind the
under-development `item_ids` feature. Compaction triggers remain request
controls whose API shape does not accept an ID.
## What changed
- Register the disabled-by-default `item_ids` feature and expose it in
`config.schema.json`.
- Make supported optional `ResponseItem` IDs serializable and expose
them in the generated app-server schemas.
- When `item_ids` is enabled, assign an ID during conversation-history
preparation if an item has no ID.
- Generate type-prefixed, hyphenated UUIDv7 IDs using the Responses API
item conventions.
- Preserve existing server IDs without rewriting them.
- Persist assigned IDs in rollouts and include them in subsequent
Responses requests.
- Remove the unsupported ID field from `CompactionTrigger` and document
why it has no ID.
- Add integration coverage for enabled ID persistence, preservation of
server IDs, and omission of generated IDs while the feature is disabled.
`prepare_conversation_items_for_history` is the single response-item ID
allocation boundary.
## Test plan
- `just test -p codex-features`
- `just test -p codex-core
response_item_ids_persist_across_resume_and_preserve_server_ids`
- `just test -p codex-core
non_openai_responses_requests_omit_item_turn_metadata`
- `just test -p codex-core
resize_all_images_prepares_failures_before_history_insertion`
- `just test -p codex-protocol`
- `just test -p codex-app-server-protocol`
- `just test -p codex-api azure_default_store_attaches_ids_and_headers`
## Why
`ResponseItem` variants do not have a consistent internal ID shape: some
variants carry required IDs, some carry optional IDs, and some cannot
represent an ID at all. The existing fields also use inconsistent serde,
TypeScript, and JSON-schema annotations. A single enum-level access path
is needed before history recording can assign and retain IDs.
This PR establishes that internal model only. It intentionally does not
generate or serialize IDs; allocation and wire persistence are isolated
in the stacked follow-up.
## What changed
- Give every concrete `ResponseItem` variant an `Option<String>` ID
field.
- Apply the same internal-only annotations to every ID field:
`#[serde(default, skip_serializing)]`, `#[ts(skip)]`, and
`#[schemars(skip)]`.
- Add `ResponseItem::id()` and `ResponseItem::set_id()` as the shared
accessors.
- Preserve IDs when history items are rewritten for truncation.
- Adapt consumers that previously assumed reasoning and image-generation
IDs were required.
- Regenerate app-server schemas so the hidden fields are represented
consistently.
The serde catch-all `ResponseItem::Other` remains ID-less because it
must remain a unit variant.
## Test plan
- `cargo check --tests -p codex-core -p codex-api -p codex-rollout-trace
-p codex-image-generation-extension`
- `just test -p codex-protocol`
- `just test -p codex-app-server-protocol`
- `just test -p codex-api -p codex-rollout-trace -p
codex-image-generation-extension`
- `just test -p codex-core event_mapping`
## Why
Stop sending duplicate `session_id`/`thread_id` headers. We only want
the hyphenated forms as `_` is rejected by some proxies
Related discussion here:
https://openai.slack.com/archives/C095U48JNL9/p1778508316923179
## What
- Keep `session-id` and `thread-id`
- Remove the underscore aliases
## Why
Some consumers expect conventional hyphenated HTTP headers. Codex
already sends the session and thread IDs on outbound Responses requests,
but it only uses the underscore spellings today, which makes those IDs
harder to consume in systems that normalize or reject underscore header
names.
Full context here:
https://openai.slack.com/archives/C08KCGLSPSQ/p1778248578422369
## What changed
- `build_session_headers` now emits both `session_id` and `session-id`
when a session ID is present.
- It does the same for `thread_id` and `thread-id`.
- Added regression coverage in `codex-api/tests/clients.rs` and
`core/tests/suite/client.rs` so both the lower-level client tests and
the end-to-end request tests assert the two header spellings are
present.
## Test plan
- Added header assertions in `codex-api/tests/clients.rs`.
- Added request-header assertions in `core/tests/suite/client.rs` for
both the `/v1/responses` and `/api/codex/responses` request paths.
## Summary
Related to
https://openai.slack.com/archives/C095U48JNL9/p1777537279707449
TLDR:
We update the meaning of session ids and thread ids:
* thread_id stays as now
* session_id become a shared id between every thread under a /root
thread (i.e. every sub-agent share the same session id)
This PR introduces an explicit `SessionId` and threads it through the
protocol/client boundary so `session_id` and `thread_id` can diverge
when they need to, while preserving compatibility for older serialized
`session_configured` events.
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
- reduce public module visibility across Rust crates, preferring private
or crate-private modules with explicit crate-root public exports
- update external call sites and tests to use the intended public crate
APIs instead of reaching through module trees
- add the module visibility guideline to AGENTS.md
## Validation
- `cargo check --workspace --all-targets --message-format=short` passed
before the final fix/format pass
- `just fix` completed successfully
- `just fmt` completed successfully
- `git diff --check` passed
## Why
to support a new bring your own search tool in Responses
API(https://developers.openai.com/api/docs/guides/tools-tool-search#client-executed-tool-search)
we migrating our bm25 search tool to use official way to execute search
on client and communicate additional tools to the model.
## What
- replace the legacy `search_tool_bm25` flow with client-executed
`tool_search`
- add protocol, SSE, history, and normalization support for
`tool_search_call` and `tool_search_output`
- return namespaced Codex Apps search results and wire namespaced
follow-up tool calls back into MCP dispatch
### What
add wiring for `phase` field on `ResponseItem::Message` to lay
groundwork for differentiating model preambles and final messages.
currently optional.
follows pattern in #9698.
updated schemas with `just write-app-server-schema` so we can see type
changes.
### Tests
Updated existing tests for SSE parsing and hydrating from history
Adds a new feature
`enable_request_compression` that will compress using zstd requests to
the codex-backend. Currently only enabled for codex-backend so only enabled for openai providers when using chatgpt::auth even when the feature is enabled
Added a new info log line too for evaluating the compression ratio and
overhead off compressing before requesting. You can enable with
`RUST_LOG=$RUST_LOG,codex_client::transport=info`
```
2026-01-06T00:09:48.272113Z INFO codex_client::transport: Compressed request body with zstd pre_compression_bytes=28914 post_compression_bytes=11485 compression_duration_ms=0
```
Fix this: https://github.com/openai/codex/issues/8479
The issue is that chat completion API expect all the tool calls in a
single assistant message and then all the tool call output in a single
response message
pakrym-oaiandGitHub
jif-oaiandGitHub
Anton PanasenkoandGitHub
sayan-oaiandGitHub
Channing CongerandGitHub