## What changed
Extend `mcp_connection_sharing` to pool compatible local stdio connections that negotiate MCP `2026-07-28`. Keep legacy servers and servers that request input during startup private.
Preserve each chat's tool catalog and route input requests to the calling chat. Release connections independently for each chat, shutting down the shared server after the final release, and retire pooled connections on forced refresh without interrupting other chats.
## Testing
Add pool, runtime, app-server, and core scenario tests covering protocol gating, startup cancellation, refresh, final-release shutdown, and separate tool visibility and simultaneous input responses across chats sharing one process.
GitOrigin-RevId: 896b107267a20ec1bffccdefca6c40fe2945a022
## What changed
Add an optional `NetworkPolicyMetadataProvider` to the MCP runtime. Advertise `codex/network-policy-meta` only to trusted ChatGPT origins when a provider is available, and attach policy metadata only when the sending session also advertises support.
Strip caller-supplied policy metadata and derive restrictions from the call's captured permission profile and server environment. Resolve metadata against each session's capabilities, including after recovery, while retaining one policy snapshot per call. Fail the call before sending if policy resolution fails. Existing runtime callers leave the provider unset.
## Testing
Add tests for capability negotiation, trusted-origin restrictions, forged metadata removal, both tool dispatch paths, and policy snapshot reuse. Add HTTP session-recovery coverage for changing capabilities and policy-resolution failures while preserving caller metadata and read-only restrictions.
GitOrigin-RevId: 4b978f986abc0475fc67659be98fc01a2d6ce7cd
## What changed
Add `experimentalDisablePredictionMcp` to `thread/fork` and `disableMcp` to `thread/sample`. Disable MCP servers when requested and the inherited history contains incremental tools on Responses Lite. The fork option requires `experimentalPredictionMode: true`.
Apply disablement through a thread-local policy that excludes configured MCP servers and runtime contributions, including after MCP refresh. Preserve the inherited history prefix and append tool-removal instructions without changing the parent's tools.
## Testing
Add coverage for prediction forks with legacy and paginated history, flag validation, conditional disablement, MCP refresh, and sample/fork request parity. Add a request-history snapshot covering preserved history, tool removal across child turns, and unchanged parent tools.
GitOrigin-RevId: e31d602480e6550ed130d8152f538b8668280fa0
## Why
A remote primary environment could supply its working directory and workspace roots to host plugins and MCP processes, breaking relative MCP executable resolution and applying the wrong workspace permissions.
## What changed
- Build host configuration from the local environment, falling back to the session's host working directory and runtime workspace roots when no local environment is selected. Preserve explicitly empty local roots.
- Use the same host configuration for MCP startup and refresh, and refresh MCP state when runtime workspace roots change.
- Keep repository skill discovery paired with the primary executor's working directory and filesystem.
- Box skill warmup and turn context construction futures to reduce enclosing future sizes.
## Testing
Extend the MCP integration test to cover a remote primary with populated, empty, or absent local roots; relative executable resolution before and after refresh; workspace-root revocation; and remote repository skill discovery.
GitOrigin-RevId: 21a73c90507b55fd94261e7bf348695ff8466a24
## What changed
Capture each environment's effective Windows sandbox backend in the MCP runtime and include it as `useMxc` in sandbox state metadata for supporting servers. Use the server's captured environment selection, including local fallback, so the local MXC preference does not leak into attached environments. Default missing backend information to `false`.
## Testing
Extend tests to cover MXC metadata handoff, attachment isolation, local fallback without a selected local environment, and preservation of captured backend settings across runtime refreshes.
GitOrigin-RevId: f559bffeff383838334e5a475b1eab608d571fa1
## What changed
- Instrument MCP OAuth loads, saves, deletes, fallback cleanup, and refresh persistence with credential-free storage metrics, distinguishing configured policy from operations on a pinned store.
- Retain the originating client across background tasks, blocking storage operations, and session recovery, including recovery after startup found no credentials.
- Preserve typed keyring and lock error categories for metrics and remove raw error details from storage warnings.
## Testing
Add tests for policy and pinned-store outcomes, best-effort cleanup failures, wrapped lock errors, and successful or failed refresh persistence without duplicate observations. Add recovery tests that verify client attribution after anonymous startup and across threads with different originators.
GitOrigin-RevId: 5ea4528bcdcf500c8ffdf1d9c7008ea52112c726
## Why
Cached executor MCP declarations must not gain access to host environment credentials when reconnecting to an executor that lacks environment credential resolution.
## What changed
- Retain credential policy through MCP registration, catalog materialization, and runtime setup. Derive selected HTTP plugin policy from the plugin's source environment.
- Reject host bearer-token fallback and transports requiring host environment headers or helpers for executor-owned declarations. Preserve host-configured credential resolution.
- Include credential policy in connection and tool catalog cache identities, and avoid reading host environment values for executor-only identities.
## Testing
Add regression coverage for legacy executors, cached declarations after a capability downgrade, policy preservation through catalog rebuilds, and connection and tool cache isolation.
GitOrigin-RevId: 2d5b85e4e98668c637c538cbe528914c936bd831
## What changed
Prepare each MCP call from the selected server's current client and catalog instead of building a full runtime binding. Match the advertised tool by server, tool name, and connector ID, and enforce current tool filters and model visibility.
Preserve the advertised `callable_namespace` and `callable_name` while using current schema, annotations, approval metadata, timeout, and permission authority for execution.
GitOrigin-RevId: 703a90926fc72bd446d83ac974162aee6439f363
## Why
MCP requests requiring user input previously failed in subagents with guidance to ask the parent agent, blocking browser sign-in, form input, and interactive tool approval in the child thread.
## What changed
Remove the root-only MCP elicitation guard and `allow_user_interaction` plumbing so subagents can surface prompts and wait for responses under the existing approval policy and automatic review rules. Connector authentication can now return retry guidance after acceptance or preserve the original failure when declined.
Keep legacy tool approvals through `request_user_input` restricted to the root thread.
## Testing
Update unit and integration coverage for subagent prompt resolution, form responses, connector authentication acceptance and decline, automatic approval, strict review, and approval-policy updates on reused connections. Update the browser sign-in scenario snapshot to show the subagent continuing after an accepted response.
GitOrigin-RevId: c226fc6dfde724ed22b91dc04dd32bbc15245bee
## Why
Environment settings saved for the next turn must not change MCP tool availability during the active turn.
## What changed
- Use one captured environment snapshot for MCP policy evaluation and runtime publication, including selections that are still starting or have failed.
- Compare both captured selections and ready environment handles when deciding whether to refresh the runtime, and rebuild the startup configuration when resolved selections change.
- Preserve the configuration origin of failed selections so MCP authority evaluation retains whether configuration comes from the thread.
- Box the MCP refresh future to keep it off the sampling request's stack.
## Testing
Add a regression test that updates the environment MCP policy while a turn waits for user input, verifies the tool remains visible when that turn resumes, and verifies it disappears on the next turn. Extend snapshot tests to cover starting and failed selections.
GitOrigin-RevId: cc2744b5137be69f000d70b0c7009b14079f39ae
## Why
Updating environment selections while a turn is running must not redirect its tools or prevent its pending environment setup from completing.
## What changed
- Store future environment selections separately from active environments, and activate them when preparing new work with no task running.
- Keep turn contexts and MCP workspace roots tied to the active environment snapshot. Report saved selections through thread settings and `environment_selections()`.
- Route environment configuration and failure callbacks to matching active or future selections so each can finish setup independently.
- Stop the running task before manual compaction adopts the saved environments.
## Testing
Add regression tests that preserve a running task's working directory and workspace roots, then adopt the saved selection for the next task. Add remote environment coverage showing that future setup can complete while the active turn waits, with each turn receiving its own capability roots.
GitOrigin-RevId: 09a6b90131d2ab2441ce2fe9b0368a3668889f31
## Why
MCP requests that need human input, including browser sign-in, must be handled by the root thread. Subagents need guidance to hand these blockers to their parent without prompting the user or automatically accepting requests that require input.
## What changed
- Reject interactive MCP elicitations and tool approval prompts in subagents with guidance to ask the parent and wait before retrying.
- Recognize browser authentication and `codex_requires_user_input` metadata even when the form schema is empty, while preserving automatic permission approvals and review decisions.
- Carry user-interaction eligibility through MCP runtime creation and connection reuse, and guard prompt registration.
- Preserve connector authentication diagnostics alongside handoff guidance, subject to normal tool-output limits.
## Testing
Add unit and integration coverage for blocked subagent prompts, root browser authentication, automatic approval and review, connection reuse, and authentication diagnostic preservation and truncation. Add a request-history snapshot for browser-auth handoff guidance.
GitOrigin-RevId: 83e146b6e5c1a2a22a34681ad45615f504b3c96c
## What changed
- Apply `disabled_plugin_ids` to plugin skills, recommendations, hooks, and MCP servers without modifying shared plugin state.
- Activate selection changes when the next task starts, keeping pending settings from changing the active runtime.
- Hide app tools contributed only by disabled plugins from model tool catalogs and search. Preserve connectors shared with enabled plugins and existing direct Apps RPC behavior.
- Include plugin identity in MCP approval keys and use that identity when persisting plugin tool approvals.
## Testing
Add regression coverage for disabling and re-enabling plugin skills and tools, deferred activation of settings, shared connector ownership, selected plugin servers, executor hooks, and plugin-specific approval keys and persistence.
GitOrigin-RevId: 1153ff6aa7ab6953d50e838da05203904ecd2956
## Why
Session isolation relied on Guardian source attribution. An explicit policy lets callers control inherited capabilities independently of how a session is attributed.
## What changed
- Add `SessionIsolation` with default `Inherit` and opt-in `Isolated` modes, captured at session startup through `ExtensionDataInit`.
- Use the policy to control inherited instructions, extensions, execution rules, and MCP resources. Isolated sessions retain managed execution rules and omit executor-discovered MCP servers.
- Explicitly isolate Guardian reviewers while preserving source-based fallback for older callers and saved reviewers.
## Testing
Extend delegate tests to cover isolation independently of attribution, update execution-policy coverage to supply the explicit policy, and assert that managed reviewers do not inherit the parent's configured MCP tools.
GitOrigin-RevId: f0ab42fa2f0237860ec661e72693ab191216afbf
## What changed
- Count remote executor MCP discovery attempts, including refreshes, with `success` and `error` outcomes.
- Count each discovered server by name and report whether it was found or unavailable before policy and startup filtering.
GitOrigin-RevId: b912aa64b606e6243cce79df0fe85d485a2c3547
## What changed
- Fetch ChatGPT account access and attach `cyber_trusted_access` under
`openai/entitlementContext` when an installed or selected plugin explicitly
requests it from a local, read-only stdio tool with no arguments.
- Reject caller-supplied entitlement context on direct MCP calls, and fall back
to an `unknown` status when access cannot be verified or the account changes
during the lookup.
- Count entitlement lookup time against the MCP tool-call timeout.
## Testing
- Cover eligible calls plus unowned, remote, HTTP, mutable, argument-bearing,
API-key, undeclared, direct, and account-switch cases in core and app-server
integration tests.
GitOrigin-RevId: 303b61585ef4530276c373d914a2d0ccef1f4ac2
## Why
Tool execution can use an environment whose sandbox configuration differs from the turn-wide configuration. Sandbox selection and process setup need to follow the environment that owns the tool request.
## What changed
- Source Windows sandbox level, legacy Landlock mode, and Windows private desktop settings from the selected turn environment across tool orchestration, unified exec, patch application, and zsh fork escalation.
- Preserve Windows sandbox level overrides in restorable thread settings and invalidate MCP configuration when that level changes.
## Testing
- Add a resume test that verifies an elevated Windows sandbox override survives thread restoration.
GitOrigin-RevId: 9d8fc46404919f5ae97c9ed712c0932a1f095e36
## Why
MCP servers attached to executor environments must retain their owner's
permission profile instead of inheriting the thread-wide sandbox authority.
## What changed
- Resolve and capture a permission profile for each enabled MCP server when
publishing the runtime, and reject calls or elicitations when that authority
is unavailable.
- Use the captured server profile for tool approval decisions, elicitation, and
sandbox metadata, including after runtime refreshes.
- Materialize `:workspace_roots` from `PathUri` values so permissions preserve
the path convention of remote executor environments.
- Give threadless app discovery and resource reads an explicit default
permission profile.
## Testing
Added coverage for per-server elicitation authority, unresolved attachments,
runtime refreshes, restricted tool calls, and foreign-platform workspace roots.
GitOrigin-RevId: 6b188d4b08b29e9971ff7aa68a7785a0cdf9e394
## Why
Model requirements must be evaluated against the permissions that will apply
after a settings update. Validating against the current profile can reject a
valid model-and-permission update or allow a later permission-only update to
invalidate the selected model.
## What changed
- Group model, reasoning, service-tier, personality, and approval inputs into
`StepSettings`, with a single apply-and-validate path.
- Apply permission and environment changes before validating step settings, so
auto-review requirements use the proposed effective permissions.
- Revalidate existing step settings when permission or environment changes alter
their constraints, and commit the update only when the complete candidate is
valid.
## Testing
Added unit and integration coverage for atomic model/permission updates,
permission-only revalidation, environment-derived constraints, and both
standalone and turn-start settings operations.
GitOrigin-RevId: f50dfbd300484a09acc51ee4607278f300ca1cd9
## What changed
- Add Windows sandbox mode, private-desktop behavior, and legacy Landlock selection to each `EnvironmentConfig`.
- Centralize sandbox context construction on `TurnEnvironment`, preserving environment-owned permissions, paths, and backend settings while applying additional permission grants.
- Use the environment-derived context for project instructions, capability discovery, file uploads, and filesystem-oriented tools.
## Testing
- Verify capability discovery uses the selected environment's permission profile and sandbox backends when they differ from the thread defaults.
GitOrigin-RevId: 7ae2fed90c8ada950f2e8431e571e9b2c793c291
## Why
Internal Guardian reviews must remain independent of parent-session customization while still honoring managed execution and environment restrictions.
## What changed
- Apply the restricted Guardian session path to both internal and subagent review sources.
- Start internal reviews without inherited user instructions, extensions, MCP servers, or multi-agent behavior.
- Preserve managed execution policy and selected environment constraints while exposing only the allowed review tools. Honor shell feature restrictions across every selected environment and retain code mode when enabled.
## Testing
- Cover internal review isolation from parent state and managed instructions.
- Cover optional tool filtering, managed shell restrictions, code mode, and secondary environment profiles.
GitOrigin-RevId: edbf7d8a6fe3ee8213a1c75bc8ec331a1cf49006
## What changed
Pass the session source associated with each MCP configuration snapshot into
selected-environment server projection. This keeps Guardian reviewer isolation
decisions aligned with the snapshot being projected instead of rereading the
session's mutable configuration.
GitOrigin-RevId: 61fd891fec13f62cfea9886d13e2f94f6f60922f
## Why
Executor-owned MCP configuration can include required servers that are unavailable. Guardian review sessions should not attempt to discover those servers or let them block an approval review.
## What changed
- Skip projecting MCP servers from selected executors when the session source is a Guardian reviewer.
- Preserve executor MCP discovery for regular thread sessions.
## Testing
Added an app-server integration test that configures an unreachable required executor MCP server and verifies that Guardian can still review an escalated command and return its decision.
GitOrigin-RevId: 5b712a3ee04e6896d5ca0cff39a32dd8e0fe0132
## What changed
- Preserve the `required` setting on HTTP MCP servers discovered from a selected executor.
- Cover delayed startup for a required executor MCP server and verify its tool is available on the first turn.
GitOrigin-RevId: df66e12233b8e1aaa7744e29c154157af8dc4776
## What changed
- Read `mcp_servers` configuration and requirements from each selected remote
executor and add eligible HTTP servers to the thread's MCP runtime.
- Bind discovered servers to the thread's concrete executor snapshot and apply
environment MCP policy and requirements. Discovery is best effort, and
executor-local servers are not treated as required at startup.
- Ignore unsupported stdio servers and HTTP configurations that depend on
environment-provided headers or header helpers.
## Testing
- Added an app-server integration test covering discovery, authenticated HTTP
tool invocation, requirements enforcement, and exclusion of stdio servers.
GitOrigin-RevId: 6e1cdcebdbb1cc21a5a2285fbc5617d8d5997182
## What changed
- Carry selected plugin identities from MCP discovery into per-turn extension data, limited to capability roots that are ready for the turn.
- Annotate executor skill catalog entries with the matching plugin ID and `user` scope.
- Include that attribution in `skill_invocation` analytics for both explicit and implicit executor skill invocations.
## Testing
- Extend the executor skills app-server test to verify plugin ID, skill scope, and invocation type for explicit and implicit analytics events.
GitOrigin-RevId: 9345600ae29bcb8eb894fffd2d6f7b05f22ebf74
## What changed
- Store `TurnEnvironmentSelection` directly on each resolved `TurnEnvironment`
instead of copying its environment ID, working directory, and workspace roots
into separate fields.
- Update environment resolution, tool execution, approvals, and related tests to
access selection state through the retained value.
GitOrigin-RevId: ab723d21e112b8af5bcaf1f772a5e376553312bc
## What changed
- Make `ThreadEnvironments` the source of truth for live environment selections and use it when building configuration snapshots, permission profiles, per-turn configuration, and MCP refresh inputs.
- Keep settings previews side-effect free while applying accepted environment updates consistently to subsequent turns.
- Move `EnvironmentConfig` into `codex-protocol` so environment ownership no longer depends on a core-only type.
## Testing
- Cover environment previews and snapshots, accepted and rejected steer updates, and active-turn environment stability.
GitOrigin-RevId: 7bcf8fb5df1215f720e4e9c419541a51a871aa5e
## What changed
- Add `http_headers_helper` configuration for local streamable HTTP MCP servers. The configured shell command runs once per connection and returns a JSON object of headers that is cached across requests.
- Apply helper headers to MCP startup and OAuth flows while restricting them to the server origin, stopping redirects, rejecting reserved or duplicate headers, and enforcing output and execution limits.
- Reject helpers for remote or managed-disabled servers, use the local environment working directory, and redact helper commands from `codex mcp list` and `codex mcp get` output.
## Testing
- Cover configuration validation, helper lifecycle and output parsing, origin isolation, OAuth discovery and token refresh, managed requirements, environment selection, and CLI redaction.
GitOrigin-RevId: 84e0e26ce75520b0869d37c72b1678e033bd6818
## Why
Standard MCP forms can require user-entered values even when tool permissions are
otherwise auto-approved in full-access sessions.
## What changed
- Recognize the `openai/standard-form-input` client extension and surface
non-approval forms in full-access, user-initiated root threads.
- Keep approval forms, automation and subagent threads, headless sessions, and
clients without the capability on their existing decline or review paths.
- Treat the capability as client-only so it is not advertised to MCP servers,
and enable it after session startup so required servers cannot block startup
waiting for form input.
## Testing
Add unit and app-server coverage for accepted form round trips, declined cases,
approval metadata safeguards, resumed threads, and extension filtering.
GitOrigin-RevId: 053bfe397a5c79eceef90a81d13e2aca6353af43
## Why
Subagents can reuse cached MCP tool definitions without starting every optional
server before any of its tools are used.
## What changed
- Defer startup for subagent-owned, optional MCP servers when their cache has at
least one visible, allowed tool, and trigger startup on the first operation
that needs the live client.
- Keep root sessions, required servers, selected plugin servers, and explicit
reconnects eager.
- Exclude empty catalogs from cache eligibility and keep dormant servers out of
the initial startup summary.
## Testing
- Extend MCP tool-cache coverage for eager root startup, unused and filtered
subagent servers, deferred startup status events, and startup that survives an
interrupted first tool call.
GitOrigin-RevId: e7528ff08312583a6747cbc6550ea5b6eabda9a6
## What changed
- Add `session_source()` to `McpServerContributionContext` for thread-scoped MCP resolution.
- Propagate each thread's `SessionSource` through initial setup, per-step resolution, and runtime refreshes.
## Testing
- Verify global contexts omit the source while thread-scoped contexts retain it.
- Verify MCP contributors observe distinct sources for a root thread and its spawned subagent.
GitOrigin-RevId: 23da1509858e023fbd9e2d179034ddc83553f17b
## Why
App-server clients need to advertise structured MCP extension settings, including supported MCP App UI MIME types, rather than only opting into OpenAI form elicitation with a boolean.
## What changed
- Add an `extensions` map to initialize capabilities and preserve `mcpServerOpenaiFormElicitation` as a legacy alias for `openai/form`.
- Capture the declared extension profile when a thread is started, resumed, or forked, propagate it to subagents, and advertise it to downstream MCP servers during initialization.
- Keep the profile stable for the lifetime of the loaded session instead of changing it on later turns or direct tool calls.
## Testing
- Cover extension conversion, downstream MCP initialization, session isolation, legacy form support, and subagent inheritance.
GitOrigin-RevId: fbcedbb74ce788e574b0f884a4c45c4cedb9de54
## What changed
- Apply the session's current approval policy whenever per-turn configuration is built.
- Have review threads inherit the parent turn's full permission settings and approval reviewer.
- Add coverage for settings updated after session startup, including the approval policy, permission profile, and approval reviewer.
GitOrigin-RevId: bff050c6de157dd65d62f7b49651bef3f426ee3f
## Why
Threads can configure the same MCP server name with different runtimes. Tool calls
must use the runtime associated with the thread that issued the call.
## What changed
- Route MCP readiness checks and call preparation through the invoking session.
- Add regression coverage that alternates calls between two threads and verifies
that each thread continues using its own MCP server process and configuration.
GitOrigin-RevId: 5735f7b29a579f545351385ab01a575e35ead01e
## Why
Executor capability discovery can traverse plugin and skill roots, including
symlinks. Under restricted filesystem permissions, discovery must not expose
files outside the permitted paths.
## What changed
- Pass each environment's filesystem sandbox context through capability root
discovery and apply it to metadata, directory walks, and file reads.
- Enable discovery for restricted sessions so permitted executor skills remain
available while inaccessible roots and symlink targets are omitted.
- Key discovery caches by sandbox context and reject sandboxed discovery on
executors that do not advertise support for it.
- Split requests with more than 128 roots into supported-size batches.
## Testing
- Cover permitted and denied external symlink targets.
- Verify restricted skill listing excludes inaccessible skills.
- Verify cache separation across permission contexts and discovery of 129 roots.
GitOrigin-RevId: 44d16468ca003403bdb8b71a04ae8c9ff94ed494
## What changed
- Track the authentication state used by each published MCP runtime and mark the runtime dirty when the auth mode, account details, or token changes.
- Refresh plugin auth mode before evaluating pending MCP work, and rebuild the initial MCP projection if authentication changes during session startup.
- Carry one auth snapshot through runtime construction so plugin discovery and MCP connections use consistent credentials.
## Testing
- Add a regression test that replaces an API key, reloads authentication, and verifies that MCP refresh publishes a runtime using the new credentials.
GitOrigin-RevId: 219c2f7a157f53b5467116e18bfe70a8c3dca695
## Why
After a remote plugin install refreshes the Apps tool catalog, a later MCP
runtime publication must not restore the catalog from the previous connection.
## What changed
- Rebuild the MCP runtime with fresh connections when hard-refreshing Apps
tools, using the latest desired runtime configuration.
- Refresh the Apps catalog on the newly published connection so subsequent
runtime updates retain it.
## Testing
Extend the remote plugin install test to verify that both newly available and
missing Apps tools remain consistent after an unrelated runtime configuration
refresh.
GitOrigin-RevId: 5b675d53d56379ab67fab09512fc2ad0ffcb8535
## 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
## What changed
- Use `McpConnectionSet` as the primary name for the collection of active MCP
server connections throughout `codex-mcp` and its callers.
- Keep `McpConnectionManager` as a backward-compatible type alias.
GitOrigin-RevId: 9753838b4fd0a0b6429a9c4af0c077137616f388
## What changed
- Let deferred environments provide selected capability roots with their ready signal.
- Validate that those roots have unique, non-empty IDs, belong to the registering environment, and stay within the root limit.
- Include roots from ready turn environments when resolving MCP contributions, and refresh the MCP runtime when the selected root set changes.
- Expose the exact ready root set to MCP contributors so executor plugins become available with their environment.
## Testing
- Cover ready-root propagation, validation failures, replacement isolation, reconnection, and MCP plugin availability refresh.
GitOrigin-RevId: ec3498aab1164824025094e96a9b1063b7b731ad
## Why
Generic plugin guidance is currently emitted only with initial context
from host plugin state. An executor-selected plugin can become available
later in the same turn, making its skills and tools usable without ever
telling the model how plugin capabilities should be used.
## What
- project every ready selected plugin package, including skill-only
plugins
- carry plugin availability with the exact MCP runtime projection while
preserving MCP manager reuse when servers and connectors are unchanged
- move generic plugin guidance from the static initial-context path into
persisted World State
- recognize legacy and retained plugin fragments so resume and
compaction do not duplicate guidance
## Testing
- `just test -p codex-mcp-extension`
- `just test -p codex-core plugins_instructions`
- `just test -p codex-core
plugin_availability_change_reuses_the_mcp_manager`
- `just test -p codex-app-server --test all selected_capabilit`
## Why
Selected plugin metadata is stable, but MCP processes are live runtime
state. They need different lifetimes:
- the MCP extension caches manifest, MCP, and connector declarations for
each stable selected root;
- each model step projects that cached metadata through the roots that
resolved as ready for that exact step;
- the MCP manager is rebuilt only when that availability projection
changes.
This matches executor skills: both features consume the same resolved
step roots instead of inferring readiness from the turn's selected
environments.
## Behavior
```text
E1 not ready for this step
-> no E1 MCP servers or connectors
-> cached plugin metadata stays in ext/mcp
E1 becomes ready
-> reuse cached metadata
-> publish one MCP runtime containing E1 capabilities
same ready roots on the next step
-> reuse the exact runtime; no rediscovery and no MCP restart
resume
-> create new extension thread state and a new MCP runtime
```
All model-facing consumers use the same step snapshot:
```text
resolved selected roots
|
v
extension MCP/connector projection
|
v
{ MCP config, connector snapshot, MCP manager }
|
+-> advertise model tools
+-> build app/connector tools
+-> execute MCP calls
```
## Cache contract
The existing MCP extension owns a cache keyed by the full
`SelectedCapabilityRoot`:
```rust
let state = thread_store.get_or_init(SelectedExecutorPluginMcpState::default);
```
The cache lives with extension thread state. Environment availability
filters projection but does not invalidate metadata. Resume creates new
thread state. There is no file watcher or executor generation because
contents behind a stable environment/root are assumed stable.
## What changes
- Keeps executor plugin discovery and cached metadata in `ext/mcp`.
- Caches MCP and connector declarations together per selected root.
- Uses the step's already-resolved capability roots, including lazy
environments that are not turn environments.
- Reuses the current MCP runtime when the ready-root projection is
unchanged.
- Uses the same step MCP manager and connector snapshot for
model-visible tools and execution.
- Resolves direct thread-scoped MCP requests from the current
selected-root projection.
## Deliberately out of scope
- `app/list` remains based on the latest global host-plugin state; this
PR does not make its response or notifications thread-specific.
- `required = true` startup semantics do not apply to delayed executor
MCP activation.
- No filesystem/content invalidation.
- No transport-disconnect watcher.
- No executor generations or environment replacement semantics.
- No client sharing across complete manager replacements.
## Stack
1. Extension-owned World State sections.
2. Project executor skills through World State.
3. Pin one MCP runtime to each model step.
4. **This PR:** project selected MCP and connector state from
extension-owned metadata.
5. Integration coverage for selected capability availability and resume.
## Verification
-
`selected_plugin_servers_use_managed_requirements_for_the_selected_root_id`
- The stacked integration PR covers unavailable to ready activation,
unchanged-runtime reuse, skills, MCP tools, connector attribution, and
cold resume.
## 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.
Charlie Marsh