## Description
This PR adds an optional `metadata` field to `ResponseItem` for
Responses API calls. Only mechanical plumbing, no actual values
populated and sent yet. Turns out just adding a new field to
`ResponseItem` has quite a large blast radius already.
This change is backwards compatible because `metadata` is optional and
omitted when absent, so existing response items and rollout history
without it still deserialize and requests that do not set it keep the
same wire shape. For provider compatibility, we strip out `metadata`
before non-OpenAI Responses requests so Azure and AWS Bedrock never see
this field.
My followup PR here will actually make use of it to start storing and
passing along `turn_id`: https://github.com/openai/codex/pull/28360
## What changed
- Added `ResponseItemMetadata` with optional `turn_id`, plus optional
`metadata` on Responses API item variants and inter-agent communication.
- Preserved item metadata through response-item rewrites such as
truncation, missing tool-output synthesis, compaction history
rebuilding, visible-history conversion, rollout/resume, and generated
app-server schemas/types.
- Strip item metadata from non-OpenAI Responses requests while
preserving it for OpenAI-shaped requests.
- Updated the mechanical fixture/test construction churn required by the
new optional field.
## Why
Importing large external-agent session histories currently starts a full
live Codex thread for every imported session. This initializes unrelated
runtime systems and repeats expensive transcript, metadata, hashing, and
ledger work.
On a 50-session, 238 MiB fixture, the existing path took roughly 70
seconds to complete the import and 77 seconds end to end.
## What changed
- Persist imported sessions directly through `ThreadStore` instead of
starting full live threads.
- Process imports through a bounded five-session pipeline.
- Parse, extract, and hash each source file in one pass.
- Move blocking source preparation onto the blocking thread pool.
- Reuse prepared content hashes and update the import ledger once per
batch.
- Avoid metadata readback for newly written rollouts.
- Preserve imported conversation history and visible thread metadata.
- Keep the implementation out of `codex-core` and avoid changes to the
public `ThreadStore` trait.
## Performance
For the same 50-session, 238 MiB fixture:
| Path | Import completion | End to end |
| --- | ---: | ---: |
| Existing import | 69.61s | 76.62s |
| This change | 5.95s | 6.58s |
All 50 sessions imported successfully with no warnings or contention
signals.
## Validation
- `just test -p codex-external-agent-sessions`
- `just test -p codex-app-server external_agent_config_import`
- Verified imports do not initialize unrelated required MCP servers.
- Verified previously imported source versions are skipped and changed
sources can be imported again.
- Verified imported rollouts remain readable through thread listing and
history APIs.
## Summary
Adds an optional `clientId` field to app-server v2 `UserInput` and
carries it through the core `UserInput` model so clients can correlate
echoed user input items without relying on payload equality.
## Details
- Adds `client_id: Option<String>` to core `UserInput` variants.
- Exposes the v2 app-server field as `clientId` on the wire and in
generated TypeScript.
- Preserves the id when converting between app-server v2 and core
protocol types.
- Regenerates app-server schema fixtures.
## Validation
- `just fmt`
- `just write-app-server-schema`
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-protocol`
- `just fix -p codex-app-server-protocol`
- `just fix -p codex-protocol`
- `git diff --check`
## Why
[Recent PR](https://github.com/openai/codex/pull/22709) removed
`trace_id` from `TurnContextItem`.
## What changed
- Add to `TurnStartedEvent` so rollout consumers can correlate turns
with telemetry traces.
- Note that the branch name is out of date because I originally re-added
to `TurnContextItem`, but we decided to move it to `TurnStartedEvent`.
## Verification
- `cargo test -p codex-protocol`
- `cargo test -p codex-core --lib
regular_turn_emits_turn_started_without_waiting_for_startup_prewarm`
- `cargo test -p codex-core --test all
emits_warning_when_resumed_model_differs`
- `cargo test -p codex-rollout`
- `cargo test -p codex-state`
## Summary
- Add optional image detail to user image inputs across core, app-server
v2, thread history/event mapping, and the generated app-server
schemas/types.
- Preserve requested detail when serializing Responses image inputs:
omitted detail stays on the existing `high` default, while explicit
`original` keeps local images on the original-resolution path.
- Support `high`/`original` consistently for tool image outputs,
including MCP `codex/imageDetail`, code-mode image helpers, and
`view_image`.
## Summary
- Support Claude Code `ai-title` / `aiTitle` records when detecting and
importing external agent sessions.
- Preserve existing `custom-title` / `customTitle` precedence; only fall
back to `aiTitle` when no custom title is present.
- Add coverage for both detection and import title selection, including
the custom-title-over-ai-title case.
## Testing
- `cargo test -p codex-external-agent-sessions`
- `just fix -p codex-external-agent-sessions`
## Summary
This extends external agent detection/import beyond config artifacts so
Codex can detect recent sessions files from the external agent home and
import them into Codex rollout history.
## What changed
- Added a focused `external_agent_sessions` module for:
- session discovery
- source-record parsing
- rollout construction
- import ledger tracking
- Wired session detection/import into the app-server external agent
config API.
- Added compaction handling so large imported sessions can be resumed
safely before the first follow-up turn.
## Testing
Added coverage for:
- recent-session detection
- custom-title handling
- recency filtering
- dedupe and re-detect-after-source-change behavior
- visible imported turn construction
- backward-compatible import payload deserialization
- end-to-end RPC import flow
- rejection of undetected session paths
- repeat-import behavior
- large-session compaction before first follow-up
Ran:
- `cargo test -p codex-app-server external_agent_config_import_ --test
all`
