## What changed
- Update the status heading from the latest usable reasoning line and retain it through tool activity and empty reasoning items. Keep completed reasoning in the expanded transcript only.
- Restore active reasoning after resume, thread switches, and session refreshes, including when earlier events have left the replay buffer.
- Default new embedded TUI threads to `model_reasoning_summary = "detailed"`, honoring explicit summary settings. Keep `concurrent_reasoning_summaries` opt-in and disable it when summaries are `none`.
- Persist the request's captured reasoning summary setting in context updates and local and remote compaction checkpoints.
- Animate status text with a smooth, grapheme-aware shimmer that respects terminal colors and reduced motion.
## Testing
Add regression coverage for reasoning status updates, transcript visibility, resume and buffered replay, outbound summary configuration, and summary settings across all three compaction modes. Add shimmer snapshots and checks for smooth brightness changes and Unicode grapheme preservation.
GitOrigin-RevId: 725c7de20f23166d7a3da6daeca617add5cbc600
## Why
Model settings can change between steps in the same turn. Token-budget defaults,
context-window limits, and model-visible guidance need to stay aligned with the
model captured for each step.
## What changed
- Preserve the turn's original token-budget preferences and resolve model-owned
defaults when each `StepContext` is created.
- Use the step's model to determine context-window availability and token-budget
guidance, while keeping explicit user settings unchanged.
- Emit one-time replacement or removal notices when context-window guidance
changes, including compatibility with previously persisted world-state
snapshots.
- Add `ModelInfo::usable_context_window()` to distinguish reserved-headroom
capacity from the resolved context window and auto-compaction limit.
## Testing
- Cover mid-turn model switches with model defaults, explicit settings, config
reloads, missing context windows, and missing destination guidance.
- Cover unchanged, replaced, removed, blank, and legacy guidance transitions.
GitOrigin-RevId: 91100a9f3625bef8a79ecd158eb028051c309eee
## Why
Thread settings can change while a turn is running, and delegated review or
compaction steps can select a different model. Each request needs a consistent
set of settings resolved against the model that will execute it.
## What changed
- Capture immutable resolved settings for each model step, including model
metadata, reasoning options, service tier, approvals, and personality.
- Keep in-flight steps on their captured settings while applying thread updates
to subsequent work.
- Resolve inherited reasoning summaries and filter service tiers against the
selected model and feature configuration for review and compaction steps.
## Testing
Added coverage for settings updates during paused turns, model changes,
previous-model compaction, review-model defaults, and service-tier filtering.
GitOrigin-RevId: fca4b3b305379f1bf26a5cac75ee0dd1747ac1f6
## Why
Thread settings can change while a turn is still active, including between sampling requests. Those updates should apply to the next turn instead of changing the model configuration partway through the current turn.
## What changed
- Snapshot the model, reasoning settings, service tier, approval settings, and model-attributed telemetry in `StepContext`.
- Build prompts, model requests, world state, tracing, and startup prewarms from that step-scoped snapshot.
- Share immutable model metadata between turn and step contexts.
## Testing
Added an integration test that pauses an active turn, updates its thread settings, and verifies that all requests in the active turn retain the original settings while the next turn uses the updates.
GitOrigin-RevId: c51352218e463dcc9b7338566d16742292c49fbf
## What changed
- Read the frozen MCP tool catalog directly from the step-scoped `McpBinding`
when building tool routers, plugin injections, and connector state.
- Remove the redundant `Vec<ToolInfo>` from `StepContext` and stop returning a
duplicate catalog from `built_tools`.
GitOrigin-RevId: d12d694e1224da3f6ccb1960868491f0d80c6e19
## What changed
- Make `McpRuntime` own the published MCP configuration, connections, elicitation routing, and selected capability roots for a thread.
- Capture immutable MCP bindings for model steps and tool calls so in-flight work keeps a consistent connection set and approval authority while refreshed state is published atomically.
- Mark MCP state dirty when relevant configuration, plugins, environments, authentication, or elicitation capabilities change, then rebuild it before the next sampling request or out-of-band MCP operation.
- Separate config reloads from server invalidation: `ReloadMcpConfig` applies resolved MCP inputs, while `RefreshMcpServers` requests reinitialization from the thread's latest state.
## Testing
- Cover refreshed state visibility for existing turns, stable step bindings, current approval authority, cancelled refresh retries, resource-client reconciliation, and Apps recovery between sampling requests.
GitOrigin-RevId: 59eabb1aa8dc083426bd18ef4d3630508f376401
## Why
Interrupting a turn while MCP tools were still starting could abort before the
submitted user input was recorded in conversation history.
## What changed
- Build and retain the MCP tool list and tool router as part of each step
snapshot, using the turn cancellation token during tool discovery.
- Record turn hooks and submitted input when cancellation occurs during startup
prewarming, pre-sampling compaction, or first-step capture.
- Reuse the captured router for sampling, compaction, and prompt debugging so
advertised and executable tools share the same request-scoped view.
## Testing
Add coverage that interrupts each affected MCP startup phase and verifies that
the user prompt remains in history before the turn-aborted marker.
GitOrigin-RevId: 6e96c6814357a55545d69b580e28f35933cfadf7
## What changed
- Remove the step-scoped `ExtensionData` argument from context, turn-input, and tool contributors.
- Pass the host's optional `McpResourceClient` through `ThreadStartInput` so extensions can retain session capabilities explicitly.
- Keep the MCP resource client in skills-owned session state for catalog loading and skill tools.
GitOrigin-RevId: bafa77bcd998aff408d6a396c5fd9ac268c4cce4
## What changed
- Add an `ExtensionData` store to each `StepContext`.
- Pass the step store to context, world-state, turn-input, and tool contributors so extensions can use capabilities bound to the current sampling step.
- Preserve the captured step context when rebuilding initial context during compaction.
GitOrigin-RevId: 51f3105d3a793f60534f122f9be8247c131c2ca5
## Why
Selected capability roots can contribute plugins, MCP servers, connectors, and
skills. Discovering each contribution separately requires repeated access to the
executor filesystem.
## What changed
- Add the `capabilityRoots/discoverV1` exec-server RPC to scan selected roots and
materialize recognized plugin manifests, configuration files, skill
instructions, and skill metadata in one bounded request.
- Add the opt-in `executor_capability_discovery` feature, with a thread-scoped
cache and per-step snapshot shared by MCP and skill discovery.
- Parse MCP, connector, and skill contributions from the materialized snapshot,
including serving cached skill instructions without another filesystem read.
## Testing
- Cover discovery limits, manifest precedence, root-local failures, cache reuse,
plugin contributions, and parity with the existing environment skill loader.
GitOrigin-RevId: f98fd2321cafb58c596db02da1f83c09d8eb375d
Follow-up to #30226.
## Why
#30226 makes Apps World State inspect the MCP tool list, while
tool-router construction reads the same list again later in the sampling
request. `list_all_tools()` walks the MCP clients and may reconnect or
wait for tools, so doing that work twice adds latency and lets context
and tool construction observe different MCP states for one request.
## What
- Add a lazy MCP tool snapshot to `StepContext`.
- Reuse that snapshot for Apps World State and tool-router construction.
- Let each new `StepContext` refresh naturally for the next sampling
request, without manager-level caching or invalidation.
## Testing
- `just test -p codex-core apps_instructions`
- `just test -p codex-core
apps_guidance_appears_after_background_recovery_within_a_turn`
## Why
An MCP refresh can replace the session's current manager while a model
step is still running. The step must execute calls through the same
manager whose tools it advertised.
## Boundary
```text
current session MCP runtime
|
| capture once for this model step
v
StepContext.mcp
- exact MCP config
- exact connection manager
- exact runtime environment context
```
```rust
pub struct McpRuntimeSnapshot {
config: Arc<McpConfig>,
manager: Arc<McpConnectionManager>,
runtime_context: McpRuntimeContext,
}
```
## Example
```text
step A captures runtime A and advertises A's tools
refresh publishes runtime B
step A tool call -> runtime A
next step -> runtime B
```
Capturing the snapshot is only an `Arc` clone. It does not restart MCPs
or make an RPC.
## What changes
- Captures one MCP runtime in `StepContext`.
- Uses it for tool planning, tool calls, resources, approvals, connector
attribution, and elicitation.
- Publishes replacement runtimes atomically.
- Lets an old runtime live only while an in-flight step or request still
holds its `Arc`.
Most of this diff is mechanical routing from the session-global manager
to `step_context.mcp`; it does not introduce selected-plugin discovery
yet.
## What does not change
- No plugin or extension migration.
- No new MCP cache policy.
- No environment file watching.
- No client sharing between separate managers.
## Stack
1. Extension-owned World State sections.
2. Project executor skills through World State.
3. **This PR:** pin one MCP runtime to each model step.
4. Project selected MCP/app/connector metadata by environment
availability.
5. One end-to-end integration scenario.
## Why
`selectedCapabilityRoots` is durable thread intent: “use this capability
root from environment `worker`.”
The important product assumption is:
> One environment ID always names the same logical executor and stable
contents.
`worker` does not silently change from executor A to an unrelated
executor B. The process-local connection handle for `worker` can still
be replaced while Codex is running, though, for example when
`environment/add` registers a fresh handle for the same logical
environment.
The thread should persist only the stable selection. Each model step
should pair that selection with the exact ready handle captured for that
step.
## The boundary
```text
persisted thread intent
plugin@1 -> environment "worker"
|
| capture the current step
v
model-step view
unavailable, or
plugin@1 + worker's exact captured ready handle
```
The environment ID is the stable identity and cache key. The
`Arc<Environment>` is only a process-local handle retained so consumers
of one model step use the same captured environment. It is never
persisted and it does not imply different environment contents.
## What changes
### Persist the stable selection
Selected roots are written into `SessionMeta` and restored with the
thread. Forked subagents inherit the same selections, including
bounded-history forks.
Only stable data is persisted: root ID, environment ID, and root path.
### Capture readiness together with the exact handle
The environment snapshot records:
```rust
environment_id -> Some(Arc<Environment>) // ready in this step
environment_id -> None // still starting in this step
```
This prevents readiness and execution from coming from different
registry snapshots.
For example:
```text
step snapshot: worker -> handle A, ready
environment/add: worker -> fresh handle B for the same logical environment
current step: plugin@1 still uses captured handle A
```
Without carrying handle A in the snapshot, the resolver could combine “A
was ready” with handle B and treat B as ready before it had finished
starting.
This does not change cache invalidation. Stable capability metadata
remains identified by environment ID and capability root. Replacing a
process-local handle under the same stable environment ID does not
invalidate or rediscover that metadata.
### Resolve availability per model step
- A ready captured environment produces resolved roots using its
captured handle.
- A starting, missing, or failed environment is omitted from that step.
- A selected lazy environment that is outside the turn's captured
environment set is asked to start, and a later step can observe it as
ready.
- No capability files are scanned here.
Transient transport disconnects remain the remote client's reconnect
concern. This PR models initial attachment/readiness; it does not add
live socket-connectivity state.
## Example
```text
thread selection: plugin@1 -> environment "worker"
step 1: worker is starting -> plugin@1 unavailable
step 2: worker is ready -> plugin@1 resolves through worker's captured handle
step 3: fresh local handle -> current step remains pinned; a later step captures its own view
```
Temporary unavailability does not discard the durable selection. Later
PRs can retain stable metadata caches while projecting only currently
available capabilities into model-visible World State.
## Compatibility
The app-server request shape does not change. Older rollouts without
`selected_capability_roots` deserialize to an empty list.
## Stack
1. **This PR:** persist stable selected roots and resolve them through
an exact model-step handle.
2. #29960: cache stable skill metadata and project available skills into
World State.
3. #29946: cache stable plugin declarations and manage the separate live
MCP runtime.
## Why
With deferred executors, a turn can begin before a remote environment
attaches. AGENTS.md discovery previously ran only during session setup,
so instructions from a later environment never reached the model or the
session instruction sources.
WorldState persistence has now landed, so this uses the durable
model-visible baseline directly instead of carrying a temporary
resume/fork compatibility path.
## What
- Add an `AgentsMdManager` in `SessionServices` to own host
instructions, loaded state, and refresh caching.
- When `DeferredExecutor` is enabled, refresh AGENTS.md when attached
environment selections change and freeze the result in the corresponding
`StepContext`.
- Represent AGENTS.md as a persisted WorldState section for every
session, with bounded initial, replacement, and removal updates.
- Remove duplicate AGENTS.md state and rendering from
`SessionConfiguration` and `TurnContext`.
- Build initial context, per-request updates, and compaction context
from the same step-scoped value.
- On resume and fork, compare current instructions with the restored
WorldState baseline and inject a replacement exactly once when they
differ.
Builds on #29833, #29835, and #29837.
## Tests
- Covers a remote environment becoming ready mid-turn, with AGENTS.md
appearing on the next request exactly once and updating canonical
instruction sources.
- Covers full, unchanged, replaced, and removed AGENTS.md WorldState
rendering.
- Covers changed instructions across cold resume and fork without
duplicate reinjection.
- Covers remote-v2 compaction retaining creation-time instructions in
the live session and cold resume appending one replacement when the
source changed.
- Ran focused `codex-core` AGENTS.md, WorldState, and context-update
test suites.
## Why
With deferred executors, an environment can become ready between two
sampling requests in the same turn. The model-visible environment
update, advertised tools, and eventual tool execution must all describe
the same request-time view.
Otherwise, a request built while only environment B is ready can
advertise a tool without an `environment_id`; if higher-priority
environment A becomes ready before execution, that call could silently
run in A instead.
This PR is stacked on #29527.
## Design
`run_turn` captures one `Arc<StepContext>` at each sampling-request
boundary. That step owns the request's `TurnContext` and environment
snapshot.
- World-state environment updates and tool planning borrow that same
step.
- `ToolCallRuntime` retains the `Arc` while asynchronous tool calls
execute.
- `ToolInvocation` carries the step to handlers; its temporary `turn`
compatibility field is derived from the same object.
- `ToolRouter` does not retain `StepContext`; it only uses it while
constructing the request's tool set.
- With `DeferredExecutor` disabled, step capture keeps using the
environments frozen at turn start.
Simply: every sampling request gets one consistent picture of its
environments, from what the model sees through where its tool calls run.
## What changed
- Build environment-dependent tool specs from the current request's
`StepContext`.
- Use that same step for unified exec, legacy shell, `apply_patch`,
`view_image`, and `request_permissions` execution.
- Hide environment-backed tools, including `request_permissions`, while
no environment is attached.
- Resolve legacy shell paths and metadata from the selected step
environment instead of the stale turn-start environment.
- Capture explicit steps at non-turn-loop boundaries such as compaction,
prompt debug, and startup prewarm.
- Reconcile prompt-debug history from the same step used to build its
tools.
## Follow-up
- Bind yielded code-mode cells to the tool runtime that created them, so
nested calls made after yielding continue to use the originating
request's `StepContext`.
## Test plan
- `just test -p codex-core
deferred_executor_updates_context_and_tools_after_startup`
- `just test -p codex-core
environment_count_controls_environment_backed_tools`
- `just test -p codex-core
build_prompt_input_includes_context_and_user_message`
## Why
Nonblocking environment snapshots allow a turn to reach the model while
a remote environment is still starting. The initial context can describe
that environment as still loading, but nothing currently refreshes the
model-visible environment context when startup finishes during the same
turn.
This adds the first request-scoped reconciliation slice on top of
#28683. It is gated by `DeferredExecutor` and intentionally updates only
model-visible environment context; tools and other environment-derived
state will migrate separately.
## What
- Add a minimal `StepContext` containing the environment snapshot
captured before each sampling request.
- Render attached environments with their resolved shell and starting
environments with `still loading`.
- Track the latest environment state recorded in model history and
append a bounded update only when it changes.
- Seed that baseline from full initial context so ready-at-start
environments are not duplicated.
- Clear the in-memory baseline when history is rewritten so replacement
history can be refreshed safely.
## Testing
- `just test -p codex-core deferred_executor`
- `just test -p codex-core
environment_context_baseline_deduplicates_until_history_is_replaced`
The integration coverage verifies that a pending environment reaches the
first request, the ready state reaches the next request, later requests
do not duplicate it, and ready-at-start environments remain
single-injected.
<details>
<summary>Live verification</summary>
- Connected to a real remote executor with startup deliberately delayed
and forced three sampling requests in one turn.
- Inspected the raw model inputs: request 1 showed the remote
environment as `still loading`, request 2 appended its ready shell and
cwd, and request 3 contained no duplicate ready update.
- With the feature disabled, startup waited for the delayed executor and
the first request contained only the ready environment.
- With a synchronously ready environment and the feature enabled, the
first request contained one environment context with no duplicate.
- Executed `pwd` and read a marker file through the remote process
runner; the command exited successfully and returned the remote cwd and
marker contents.
</details>
Felipe Coury