## Why
Multi-agent V2 normally derives its mode instructions from reasoning
effort: Ultra enables proactive delegation, while other efforts require
an explicit request. Some deployments need to provide one configured
delegation policy that replaces those built-ins and remains stable when
reasoning effort changes.
## What changed
- Add `features.multi_agent_v2.multi_agent_mode_hint_text` alongside the
existing root and subagent hint settings.
- Treat any configured value, including an empty string, as
`MultiAgentMode::Custom(hint_text)`, so the configured text replaces the
built-in explicit-only and proactive policies.
- Persist the full custom variant and hint text in the turn-context
snapshot, so the durable comparison baseline detects both
reasoning-effort changes and configured policy-text changes.
- Preserve the existing explicit-only/proactive behavior when the
setting is absent.
- Replace the ambiguous `MultiAgentMode::None` variant with
`MultiAgentMode::Custom(String)` in new rollouts and API schemas. A
compatibility wire type maps legacy serialized `none` values to
`Custom("")` when resuming existing rollouts.
- Regenerate the config and app-server schemas.
## Configuration examples
The distinction is whether `multi_agent_mode_hint_text` is present. An
empty string is still a configured value and intentionally suppresses
the built-in mode instructions.
### Unset: preserve existing effort-derived behavior
```toml
[features.multi_agent_v2]
enabled = true
# multi_agent_mode_hint_text is omitted
```
- Ultra reasoning uses the built-in proactive delegation instructions.
- Other reasoning efforts use the built-in explicit-request-only
instructions.
### Empty: suppress all mode hint text
```toml
[features.multi_agent_v2]
enabled = true
multi_agent_mode_hint_text = ""
```
This selects effective mode `custom` at every reasoning effort and
injects an empty mode body, suppressing both built-in policies.
### Set: always use the configured text
```toml
[features.multi_agent_v2]
enabled = true
multi_agent_mode_hint_text = "Delegate to subagents when it will materially improve the result."
```
This selects effective mode `custom` at every reasoning effort and
injects the configured text verbatim instead of either built-in policy.
## Verification
- `just test -p codex-core multi_agent_mode`
- Covers a configured hint across High and Ultra reasoning efforts and
verifies the full custom hint is recorded for both turns.
- Covers an empty-string override suppressing both built-in instruction
bodies.
- `just test -p codex-protocol -p codex-app-server-protocol`
- Covers legacy `none` turn-context deserialization as `Custom("")` and
verifies the regenerated schemas.
Approval responses were keyed only by string ID and could return values the server did not offer. That allowed one approval kind to consume another kind’s waiter and trusted client-supplied persistence payloads too broadly.
Key pending approvals by request kind, record the exact accepted ReviewDecision values, and consume each waiter once before applying an amendment or continuing execution. Preserve ordinary session approval and the exact server-proposed restrictive network-deny path, while treating unoffered responses as denied.
Route delegated cancellation to the matching exec or patch waiter and keep Guardian-only reviews independent of the approval ledger. Add unit, integration, delegation, and telemetry coverage for exact payloads, kind isolation, cancellation, replay, and compatibility.
## Why
App-server deployments can consume structured JSON logs for operational
measurements without requiring an OTEL exporter. Existing tool-result
telemetry reports the handler outcome, but it does not separate time
spent waiting to dispatch from time spent executing the handler.
A compact completion event for the outer, direct tool call lets
consumers measure those phases and correlate them with a conversation
and turn. Code-mode calls are intentionally excluded so nested runtime
calls do not create overlapping events that are easy to double-count.
## What changed
- Added a
[`ToolCallTimingGuard`](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/core/src/tools/parallel.rs#L32)
around direct tool calls. Event-only strings and timing state are
captured only when the `codex_core::tools::parallel` `INFO` target is
enabled.
- Added a
[`codex.tool_call`](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/core/src/tools/parallel.rs#L313)
completion event with conversation, turn, tool, call, trace, dispatch,
handler, and total timing fields.
- Recorded the execution-start marker after the dispatch lock is
acquired. Event emission snapshots that marker once so a concurrently
starting dispatch cannot produce internally inconsistent fields.
- Limited the event to `ToolCallSource::Direct`; [unit
coverage](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/core/src/tools/parallel.rs#L365)
verifies code-mode calls are ignored.
- Added [cancellation
coverage](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/core/src/tools/parallel.rs#L408)
that holds the execution gate and verifies a call cancelled before
admission emits exactly one dispatch-only timing event.
- Added reusable
[`JsonLogCapture`](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/app-server/tests/common/json_logging.rs#L15)
support, a [JSON-logging-specific `TestAppServer`
constructor](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/app-server/tests/common/test_app_server.rs#L172),
and an [end-to-end app-server
test](https://github.com/openai/codex/blob/141110a73cff041c42fd51f47e363e83df1dde51/codex-rs/app-server/tests/suite/logging.rs#L52)
that drives a direct `exec_command` through the public v2 JSON-RPC API
and validates the emitted JSON event.
Exec-server-specific request and process timing remains in the stacked
PR #30901.
## Suggested logging filter
```bash
LOG_FORMAT=json \
RUST_LOG='warn,codex_core::tools::parallel=info' \
codex app-server
```
## Event example
Identifier and timing values are illustrative.
### `codex.tool_call`
```json
{
"timestamp": "2026-06-27T03:45:20.443Z",
"level": "INFO",
"fields": {
"message": "tool call completed",
"event.name": "codex.tool_call",
"trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
"conversation.id": "67e55044-10b1-426f-9247-bb680e5fe0c8",
"turn_id": "019f04f8-6ac2-78f1-8625-f04a6d35af18",
"tool_name": "exec_command",
"call_id": "call_7b8483",
"tool_source": "direct",
"execution_started": true,
"dispatch_duration_ms": 12,
"handler_duration_ms": 431,
"total_duration_ms": 443
},
"target": "codex_core::tools::parallel"
}
```
If execution never starts, `execution_started` is `false`,
`handler_duration_ms` is `0`, and `dispatch_duration_ms` covers the full
observed lifetime.
If a duration cannot be represented as an unsigned 64-bit millisecond
value, all three duration fields are omitted rather than populated with
a sentinel that could corrupt downstream calculations.
## Test plan
- `just test -p codex-core
tool_call_timing_guard_ignores_code_mode_source`
- `just test -p codex-core
cancellation_before_dispatch_admission_logs_dispatch_only_timing`
- `just test -p codex-app-server
app_server_emits_structured_tool_call_timing_event`
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/30334).
* __->__ #30334
## Summary
The Responses API may or may not send back metadata on response items.
So when comparing request data to the last response, we should discard
it and only consider the content. This change results in a higher
success rate of incremental requests.
Notably, there is one subtle change to the behavior here - we are
now ignoring metadata when comparing the previous request items to the
new request items as well. This should be fine, since the metadata is
explicitly out of scope for the comparison, regardless of whether the
item is an item from the request or response.
## Testing
- [x] Added unit test coverage for both cases of metadata existence and
absence.
## Why
Codex telemetry pipeline needs a per-request TTFT value. The existing
`codex.turn_ttft` is recorded once per turn, so it cannot represent
later inference requests in the same turn and can miss the beginning of
hidden reasoning.
This restores the low-volume per-request signal proposed in
https://github.com/bk-nvidia/codex/pull/3 without bringing back
per-WebSocket-event TRACE logging.
## What changed
- start a timer when each mapped Responses stream begins
- latch the timer on the first `response.output_item.added`, including
an empty hidden-reasoning item
- attach `ttft_ms` to the existing `codex.sse_event` /
`response.completed` telemetry record
- cover the new completion field with an integration test
## Semantics
The value is per inference request, not per turn. It measures
mapped-stream-to-first-output-item latency, matching the
customer-proposed metric. For HTTP, the stream is already established
before timing begins, so request setup and response-header latency are
excluded.
`response.output_item.added` is a client-visible proxy for the start of
hidden reasoning; this does not claim access to the server's internal
first raw-token timestamp.
## Validation
- `just test -p codex-otel` (47 passed)
- `just test -p codex-core process_sse_emits_completed_telemetry` (1
passed after the final timer-placement change)
- attempted `just test -p codex-core`: 2,855 passed and 53 failed
because of unrelated local-environment failures (missing
`test_stdio_server` fixture binary, shell startup noise, and
timing-sensitive tests); the focused telemetry test passed in that run
as well
## Why
[#30867](https://github.com/openai/codex/pull/30867) makes
`submit_inter_agent_communication` the common outbound sink for
multi-agent v2 communications. This follow-up uses that single point to
log every communication lifecycle without requiring new hooks as spawn,
messaging, follow-up, or result paths evolve.
For each communication, the logs need to identify its type, sender and
receiver threads, and content, while correlating the successful send
with receipt by the destination mailbox. The logging path must not query
externally supplied time providers because those calls can be expensive
for app-server clients.
## What changed
- Added structured `INFO` events on the OpenTelemetry-exported
`codex_otel.agent_communication` target for `spawn`, `message`,
`followup`, and `result` communications.
- Logged successful sends from `submit_inter_agent_communication` with
the communication kind, sender and receiver thread IDs, content, and
submission ID.
- Logged receives after the communication has been enqueued in the
receiver mailbox, using the same submission ID.
- Avoided time-provider calls and other asynchronous work in the logging
path.
- Narrowed ordinary spawn and send-input APIs to `Vec<UserInput>` so
`Op::InterAgentCommunication` cannot bypass the context-bearing
centralized path.
The refactor does not change submission IDs, capacity checks, last-task
bookkeeping, mailbox ordering, protocol types, rollout data, or
model-visible context.
## Event shape
Illustrative JSON representation of the two independently emitted
records:
```json
[
{
"event.name": "codex.agent_communication",
"communication_id": "019f20e1-40d1-7890-a123-456789abcdef",
"kind": "spawn",
"state": "send",
"sender_thread_id": "019f20df-fbe1-7890-a123-456789abcdef",
"receiver_thread_id": "019f20e1-3f79-7890-a123-456789abcdef",
"content": "inspect the repository"
},
{
"event.name": "codex.agent_communication",
"communication_id": "019f20e1-40d1-7890-a123-456789abcdef",
"state": "receive"
}
]
```
Consumers join the receive record to the send record by
`communication_id` for the immutable communication metadata.
## Testing
- Extended the existing end-to-end multi-agent v2 spawn test to verify
content, both thread IDs, and a correlated send/receive submission ID.
- Re-ran focused control and handler coverage for direct messages,
follow-up tasks, and completion results.
## Why
Multi-agent v2 communications currently use separate outbound paths:
direct messages, follow-up tasks, and completion results go through
`send_inter_agent_communication`, while a spawn's initial message goes
through the generic input submission path. That split makes it difficult
to add complete communication lifecycle logging in one place.
This refactor makes `submit_inter_agent_communication` the common sink
for those paths, preparing the follow-up observability work discussed in
[#30516](https://github.com/openai/codex/pull/30516).
## What changed
- Routed all current outbound `InterAgentCommunication` paths in
`AgentControl`—direct messages, follow-up tasks, completion results, and
multi-agent v2 spawn initial messages—through
`submit_inter_agent_communication`.
- Centralized the actual submission and last-task-message bookkeeping
there, providing one place for the follow-up PR to instrument
communication creation and successful enqueue.
- Left non-communication input handling and the multi-agent v1 spawn
flow unchanged.
## Testing
- `just test -p codex-core 'agent::control::tests::'` (51 passed)
- `just test -p codex-core
'suite::subagent_notifications::encrypted_multi_agent_v2_spawn_sends_agent_message_to_child'`
(passed)
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/30867).
* #30872
* __->__ #30867
## Why
The Bedrock GPT-5.6 catalog advertises `max`, but Codex treated it as an
opaque custom effort. That made the reasoning picker render it as
lowercase `max` while known efforts use productized labels.
Making `max` a known effort aligns catalog data, parsing, and UI
presentation without changing the `max` wire value or persisted
representation.
## What changed
- Add first-class `ReasoningEffort::Max` parsing and serialization.
- Use the typed effort in the Bedrock catalog and render it as `Max` in
the TUI.
- Preserve forward-compatible custom-effort coverage with a genuinely
unknown `future` value.
### Before
<img width="559" height="124" alt="Screenshot 2026-06-28 at 12 08 47 PM"
src="https://github.com/user-attachments/assets/7c43cf4f-020b-4605-9239-0a9c97eb7364"
/>
### After
<img width="558" height="107" alt="Screenshot 2026-06-28 at 12 09 10 PM"
src="https://github.com/user-attachments/assets/b9cc5ded-c940-43b4-b024-bba25abe0a17"
/>
## Summary
- restore the v1 clarification that requests for depth, research, or
investigation do not authorize subagent spawning
- restore guidance for keeping critical-path, urgent, tightly coupled,
or difficult work local
- update the focused v1 tool-search and spawn-description coverage
## Why
PR #27919 simplified the v1 `spawn_agent` prompt by removing its
delegation decision guidance. That left the authorization rule intact,
but removed the instructions that constrained what should be delegated
after spawning was authorized.
Restore those guardrails while preserving later support for explicit
delegation authorization from applicable AGENTS.md and skill
instructions. Multi-agent v2 prompts are unchanged.
## User impact
Models using the v1 multi-agent tool surface receive clearer guidance to
delegate independent side work while keeping blocking work on the main
rollout.
## Validation
- `just fmt`
- `git diff --check`
- tests not run locally per repository guidance; CI will validate the
focused coverage
## Summary
- add a false-by-default `include_skills_usage_instructions` model
metadata field
- enable the field for the bundled `gpt-5.5` model metadata
- consume the metadata in both core and extension skill rendering
- remove hardcoded legacy-model matching and its marker plumbing
## Summary
- enable the remote plugin feature by default
- promote the remote plugin feature from under development to stable
- preserve the existing `features.remote_plugin` override for explicitly
disabling it
- keep legacy disabled-path coverage explicit in TUI and app-server
tests
## Impact
Remote plugin functionality is enabled by default for configurations
that do not set the feature flag. The existing Codex backend
authentication gate still applies.
## Validation
- `just fmt`
- `just test -p codex-features`
- `just test -p codex-tui
plugins_popup_remote_section_fallback_states_snapshot`
- targeted `codex-app-server` plugin-list and skills-list tests
- `git diff --check`
The full TUI and app-server suites were also exercised locally. All
remote-plugin-related coverage passed; unrelated local
sandbox/test-binary failures remain outside this change.
## Why
Response item IDs represent stable conversation identity.
`ContextManager::for_prompt` repairs an unmatched call by synthesizing
an `"aborted"` output in the disposable prompt projection, but that
output previously had no ID. Assigning a fresh ID on every prompt build
would make retries and resumes change otherwise identical model context
and reduce prompt-cache reuse.
The concrete bug is that these normalization-created outputs bypass the
regular item-ID allocation path. Even with item IDs enabled, a prompt
could therefore contain an identified call paired with a synthetic
output whose `id` was missing. This change closes that gap by deriving
the output ID from the source call's item ID. For legacy calls that have
no item ID, the output remains ID-less because there is no stable source
identity to derive from.
The originating call already has a stable item ID under the item-ID
model introduced in #28814. A prompt-only output can therefore derive
stable identity from that call without mutating canonical history or
persisted rollouts. This addresses the failure exposed by #30311 while
keeping normalization read-only outside its detached prompt snapshot.
UUIDv5 is intentional here because it is the standard namespaced,
deterministic UUID construction. Using the output kind and source call
ID as the name produces the same UUID on every projection while keeping
output kinds in separate name domains. UUIDv7 would introduce randomness
and time, so keeping it stable would require persisting the synthetic
repair. UUIDv5 uses SHA-1 internally, but this is only an identity
mapping—not an authenticity or security boundary.
## What changed
- Derive a deterministic UUIDv5 ID for each synthesized call output from
the source call item ID.
- Use the Responses API prefix appropriate for function, custom-tool,
tool-search, and local-shell outputs.
- Preserve the existing insertion position immediately after the
unmatched call.
- Keep synthesized outputs prompt-only; no rollout, task-lifecycle,
compaction, or raw-response behavior changes.
## Testing
- `just test -p codex-core
for_prompt_assigns_stable_id_to_synthetic_output_without_reordering_history`
- `just test -p codex-core
synthetic_call_output_id_is_stable_across_resumes`
- `just test -p codex-core normalize_adds_missing_output`
- `just test -p codex-core response_item_ids`
## Summary
- Preserve the optional namespace on custom tool calls during response
deserialization and app-server replay.
- Use the namespaced tool identifier for streaming argument handling and
tool dispatch.
- Regenerate app-server protocol schemas.
- Add regression tests covering namespace serialization and routing.
## Testing
- Ran affected protocol and app-server test suites.
- Ran the full core test suite; two load-sensitive timing tests passed
when rerun individually.
- Ran Clippy and formatting checks.
- Verified with a local end-to-end app-server replay that the namespace
is preserved through the complete request/response flow.
## Why
Remote diff-root discovery is independent of world-state construction,
but it ran afterward and added filesystem metadata latency before the
first model request. Overlap the independent work so thread-cold turns
do not pay those waits serially.
## What
- Run `record_context_updates_and_set_reference_context_item` and
`turn_diff_display_roots` with `tokio::join!`.
- Reuse the same resolved display roots when constructing
`TurnDiffTracker`; no cache or behavior lifecycle changes are
introduced.
## Validation
A synthetic executor-skill benchmark with artificial network delay:
thread-cold model-request p50 improved from about 1.79 s to 1.58 s.
## Summary
- complete unified-exec processes from the ordered event stream instead
of issuing a final zero-wait `process/read`
- add optional executor sandbox-denial state to `process/exited`
- retain `process/read` as a retained-output and compatibility fallback
for receiver lag, sequence gaps, and legacy servers
- recover sandbox-denial state across transport reconnection
- cover the real `TestCodex` remote-exec path without adding a public
test-only event constructor
## Why
A successful one-shot tool call currently receives its output and
terminal notifications, then pays another wide-area `process/read` round
trip before returning. Staging traces showed that remote response wait
accounted for more than 99.8% of RPC time; local serialization,
queueing, and deserialization were below 0.6 ms.
## Measured impact
A direct staging A/B used the same build and route and changed only
completion mode. Each arm ran three times with 30 one-shot
`/usr/bin/true` calls per run. The table reports the median of the three
per-run percentiles.
| Metric | Final `process/read` | Pushed events | Change |
| --- | ---: | ---: | ---: |
| End-to-end completion p50 | 159.5 ms | 118.7 ms | -40.8 ms (-25.6%) |
| End-to-end completion p95 | 182.4 ms | 131.7 ms | -50.6 ms (-27.8%) |
| Completion-wait p50 | 80.1 ms | 41.5 ms | -38.5 ms (-48.1%) |
| Final `process/read` RPC p50 | 79.9 ms | eliminated | -79.9 ms |
TCP_NODELAY was enabled in both A/B arms, so its effect cancels out. The
successful, complete, in-order event path issued zero final
`process/read` calls.
## Compatibility and recovery
- new servers send `sandboxDenied` on `process/exited`
- legacy servers omit it, which triggers one compatibility
`process/read`
- broadcast lag or a sequence gap triggers a retained-output read
- recovery remains bounded by the server's existing 1 MiB
retained-output window
- complete, in-order event streams issue no completion read
- sandbox denial is attached to the exit event before consumers can
observe process completion
- server-first and client-first rollouts remain wire-compatible;
server-first realizes the latency win immediately
## Integration coverage
The `TestCodex` suite exercises four distinct remote-exec contracts:
- complete pushed output/exit/close with zero reads
- direct pushed sandbox denial with zero reads
- legacy missing denial metadata with exactly one compatibility read
- count-bounded replay eviction recovered from retained output without
duplication
## Validation
- `just test -p codex-core
exec_command_consumes_pushed_remote_process_events`: 4 passed
- `just test -p codex-core unified_exec::process_tests::`: 4 passed
- `just test -p codex-exec-server`: 294 passed, 2 skipped
- `just test -p codex-exec-server-protocol`: 5 passed
- `just test -p codex-rmcp-client`: 89 passed, 2 skipped
- focused Bazel `//codex-rs/core:core-all-test`: passed across 16 shards
- scoped `just fix` passed for core and exec-server
- `just fmt` passed
The complete workspace suite was not rerun; focused Cargo and Bazel
coverage passed for the changed behavior.
## Description
This PR adds canonical core `TurnItem` shapes for command execution,
dynamic tool calls, collab agent tool calls, and sub-agent activity, to
be stored in the rollout file soon.
It also teaches app-server protocol / `ThreadHistoryBuilder` how to
render those items, and adds the small legacy fanout helpers needed for
existing event-based consumers. No core producer or rollout persistence
behavior changes here, that will be done in a followup.
## Making ThreadHistoryBuilder stateless
This is the first PR in a stack to make `ThreadHistoryBuilder` stateless
enough that we can materialize app-server `ThreadItem`s from only a
given slice of `RolloutItem` history, without ever needing to replay the
whole thread from the beginning.
The persisted legacy `RolloutItem::EventMsg` records are mostly shaped
like live UI events, not like materialized `ThreadItem`s. They work if
we replay the full rollout in order, but they often do not contain
enough stable identity or complete item state to project an arbitrary
suffix on its own.
A few examples:
- `UserMessageEvent` and `AgentMessageEvent` have content, but
historically do not carry the persisted app-server item ID that should
become the SQLite primary key.
- `AgentReasoningEvent` and `AgentReasoningRawContentEvent` are
fragments. `ThreadHistoryBuilder` currently merges them into the last
reasoning item, which means a slice starting in the middle of reasoning
cannot know whether to append to an earlier item or create a new one.
- `WebSearchEndEvent`, `McpToolCallEndEvent`, collab end events, and
similar legacy events can often render a final-looking item, but they
usually rely on prior replay state to know which turn owns the item.
- Begin/end legacy events are partial views of one logical item. The
builder correlates them by `call_id` and mutates prior state to
synthesize the final `ThreadItem`.
That is the problem this direction fixes. A persisted canonical
lifecycle record looks much closer to the read model we actually want
later:
```rust
ItemCompletedEvent {
turn_id,
item: TurnItem { id, ...full snapshot... },
completed_at_ms,
}
```
Once rollout has explicit `turn_id`, stable `item.id`, and a canonical
completed item snapshot, the future SQLite projector can reduce only the
new rollout suffix and upsert the affected `thread_items` rows. It no
longer needs to synthesize `item-N`, infer item ownership from the
active turn, or replay earlier events just to reconstruct the current
item snapshot.
## What changed
- Added core `TurnItem` variants and item structs for command execution,
dynamic tool calls, collab agent tool calls, and sub-agent activity.
- Added conversions from those canonical items back into the legacy
event shapes where current consumers still need them.
- Added app-server v2 `ThreadItem` conversion for the new core item
variants.
- Taught `ThreadHistoryBuilder` and rollout persistence metrics to
recognize the new item variants.
## Follow-up
The next PR https://github.com/openai/codex/pull/30283 switches the live
core producers for these item families onto canonical `ItemStarted` /
`ItemCompleted` events.
### Summary
Release live thread persistence when a session ends because its
submission channel closes. This prevents a later same-process resume
from failing with `thread ... already has a live local writer`.
### Details
The issue is in the `codex-core` session teardown path used by Codex
hosts, rather than in Managed Agents API or exec-server itself.
Explicit shutdown already closes the `LiveThread`, which releases the
process-scoped writer held by `LocalThreadStore`. The
submission-channel-close fallback ran runtime and extension teardown but
skipped that persistence shutdown, leaving the thread ID registered as
having a live writer.
This change:
- closes the `LiveThread` on the channel-close fallback path;
- preserves the existing teardown order used by explicit shutdowns;
- extends the lifecycle regression test to assert that the thread store
receives `shutdown_thread`.
Context: [original
report](https://openai.slack.com/archives/C0B4NBHQGTV/p1782136364948039),
[recent occurrence
1](https://openai.slack.com/archives/C0B4NBHQGTV/p1782434817895839?thread_ts=1782136364.948039&cid=C0B4NBHQGTV),
[recent occurrence
2](https://openai.slack.com/archives/C0B4NBHQGTV/p1782335107474429?thread_ts=1782136364.948039&cid=C0B4NBHQGTV)
### Testing
- `just test -p codex-core
submission_loop_channel_close_runs_full_thread_teardown`
- `just test -p codex-core --lib` (1,989 passed; 3 skipped)
- `just fix -p codex-core`
- `just fmt`
- Native code review: no findings
I also attempted `just test -p codex-core`. The new regression passed;
79 unrelated integration tests failed in the local harness, primarily
because helper binaries such as `test_stdio_server` were unavailable,
plus local proxy/shell timing failures.
## Description
This adds stable optional `turnId` support to `thread/fork`. When
supplied, the fork copies persisted history through that terminal turn,
inclusive, and drops later turns from the new thread.
Omitting or passing `null` preserves the existing full-history fork
behavior, including the interruption marker when the stored source
history ends mid-turn.
## Why
We're deprecating `thread/rollback` and this will help certain UX use
cases work around it by using `thread/fork` + `turn_id` instead.
## Why
Admins need persistent defaults for the model, reasoning effort, and
service tier shown when the Desktop App creates a new thread. These are
initialization defaults rather than runtime constraints: the App should
use them to initialize its draft while still allowing a user to make an
explicit selection.
The app-server therefore needs to expose the managed values before
thread creation without changing `thread/start` behavior for other
clients.
## What changed
- Parse `model`, `model_reasoning_effort`, and `service_tier` from
`[models.new_thread]` in `requirements.toml`.
- Compose the `models` requirements through the existing
requirements-layer precedence rules.
- Expose the resolved values through `configRequirements/read` as
`requirements.models.newThread`.
- Add the corresponding app-server protocol types and regenerate the
JSON and TypeScript schema fixtures.
- Document the new `configRequirements/read` fields in the app-server
README.
## Scope
This PR is data plumbing only. It does not apply these values during
`thread/start` and does not change thread creation for existing
app-server clients, resumed or forked sessions, internal or subagent
sessions, `codex exec`, or the TUI. A companion Desktop App change owns
draft initialization, sends the effective settings for ordinary and
prewarmed starts, and preserves explicit user changes.
## Validation
- Requirements deserialization coverage for `[models.new_thread]`
- Requirements-layer precedence coverage
- App-server API mapping coverage
- `configRequirements/read` integration coverage
- Regenerated app-server JSON and TypeScript schema fixtures
## Description
This PR adds a new `historyMode = "legacy" | "paginated"` to `Thread`.
This will be stored in `SessionMeta` in the JSONL rollout file and as a
new column in the SQLite thread_metadata table, and exposed on
`thread/start` and on the `Thread` object in app-server.
## What changed
- Added canonical `ThreadHistoryMode` with `legacy` and `paginated`,
defaulting old and new SessionMeta to `legacy`.
- Carried `history_mode` through core session config, ThreadStore stored
metadata, local/in-memory stores, rollout metadata extraction, and the
existing SQLite `threads` table.
- Added experimental `historyMode` to app-server v2 `Thread` and
`thread/start`.
- Made paginated stored threads metadata-discoverable but unsupported
for legacy full-history reads, `load_history`, live resume, and create
paths.
- Regenerated app-server schema fixtures and added
protocol/state/thread-store/app-server coverage for persistence and
fail-closed behavior.
## Compatibility floor
Because users may be running various versions of Codex binaries on the
same machine (TUI, Codex App, etc.), we will need to establish a
compatibility floor for upcoming paginated threads, which will change
how thread storage reads and writes work.
The overall plan here:
```
Release N:
- Add historyMode to SessionMeta / Thread / SQLite metadata.
- Teach binaries to understand paginated threads.
- If a binary sees `historyMode="paginated"` but does not support the paginated contract, it refuses to resume/mutate the thread.
- Default remains `"legacy"`.
Release N+1:
- First-party clients start opting into paginated threads where appropriate.
- Internal dogfood / staged rollout.
- Measure old-client usage and paginated-thread unsupported errors.
Release N+2:
- Only after Release N+ is overwhelmingly deployed, make paginated the default.
- Accept that a small tail of N-1-or-older binaries may not understand paginated threads.
```
The important behavior change is fail-closed handling for a binary that
encounters a persisted `paginated` thread before it knows how to fully
support paginated history. In app-server, if a thread is `paginated`, we
will:
- allow metadata-only discovery paths like `thread/list` and
`thread/read(includeTurns=false)`, so clients can still see the thread
and inspect its `historyMode`
- reject legacy full-history/live-thread paths like
`thread/read(includeTurns=true)` and `thread/resume` with an unsupported
JSON-RPC error
- avoid silently treating an unknown or future `historyMode` as `legacy`
Under the hood, the ThreadStore layer also rejects legacy operations
that would need to load or replay the full thread history for a
paginated thread. That gives us the behavior we want for Release N:
future paginated threads are visible, but this binary fails closed
instead of trying to operate on them as if they were legacy threads.
## Why
MCP runtime reuse was keyed by every ready selected-capability
environment, even when an environment contributed no MCP servers or
connectors.
For example:
1. a global stdio MCP is running;
2. a selected remote environment contains only a skill;
3. that environment becomes ready;
4. the MCP and connector projection stays exactly the same;
5. Codex nevertheless rebuilds the MCP manager and restarts the global
stdio process.
That restart can interrupt active calls and discard process-local state
even though nothing about MCP changed.
## What changes
When selected-environment availability changes, Codex now resolves the
candidate MCP and connector projection before deciding whether to
replace the runtime:
- if the winning MCP servers or their ownership change, rebuild as
before;
- if the selected connector snapshot changes, rebuild as before;
- if an enabled MCP is explicitly bound to an environment whose
availability changed, rebuild as before;
- otherwise, keep the exact live manager and processes, and update only
the availability input remembered by the snapshot.
```text
ready selected environments: [] -> [skills-env]
resolved MCP servers: {global_probe} -> {global_probe}
resolved connectors: {} -> {}
result: reuse manager; keep the same process
```
The comparison uses the resolved winning servers and their sources, so
plugin/config ownership remains part of the runtime identity.
## Existing stack coverage
The integration PR directly below this one already covers both rebuild
boundaries: a selected MCP becomes callable and a selected connector
tool becomes model-visible when their environment becomes available. It
also verifies that an unchanged selected MCP runtime keeps its process.
This PR does not add another remote-attachment integration scenario for
the no-change optimization. `environment/add` returns before readiness,
and app-server does not currently expose a deterministic readiness
signal for an environment that contributes only skills. Keeping a
fixed-delay test would add flake risk; adding a new readiness API would
be outside this fix.
## Scope and assumptions
- This does not change skill discovery, World State rendering, or plugin
metadata caching.
- This does not add file watching or hot reload behavior.
- This does not change disconnect/reconnect handling.
- Selected environment IDs and their capability contents retain the
stack's existing stability assumption.
- Delayed `required = true` executor MCP behavior remains out of scope.
Chris Bookholt