Commit Graph

22 Commits

  • [mcp] Expand tool search to custom MCPs. (#16944)
    - [x] Expand tool search to custom MCPs.
    - [x] Rename several variables/fields to be more generic.
    
    Updated tool & server name lifecycles:
    
    **Raw Identity**
    
    ToolInfo.server_name is raw MCP server name.
    ToolInfo.tool.name is raw MCP tool name.
    MCP calls route back to raw via parse_tool_name() returning
    (tool.server_name, tool.tool.name).
    mcpServerStatus/list now groups by raw server and keys tools by
    Tool.name: mod.rs:599
    App-server just forwards that grouped raw snapshot:
    codex_message_processor.rs:5245
    
    **Callable Names**
    
    On list-tools, we create provisional callable_namespace / callable_name:
    mcp_connection_manager.rs:1556
    For non-app MCP, provisional callable name starts as raw tool name.
    For codex-apps, provisional callable name is sanitized and strips
    connector name/id prefix; namespace includes connector name.
    Then qualify_tools() sanitizes callable namespace + name to ASCII alnum
    / _ only: mcp_tool_names.rs:128
    Note: this is stricter than Responses API. Hyphen is currently replaced
    with _ for code-mode compatibility.
    
    **Collision Handling**
    
    We do initially collapse example-server and example_server to the same
    base.
    Then qualify_tools() detects distinct raw namespace identities behind
    the same sanitized namespace and appends a hash to the callable
    namespace: mcp_tool_names.rs:137
    Same idea for tool-name collisions: hash suffix goes on callable tool
    name.
    Final list_all_tools() map key is callable_namespace + callable_name:
    mcp_connection_manager.rs:769
    
    **Direct Model Tools**
    
    Direct MCP tool declarations use the full qualified sanitized key as the
    Responses function name.
    The raw rmcp Tool is converted but renamed for model exposure.
    
    **Tool Search / Deferred**
    
    Tool search result namespace = final ToolInfo.callable_namespace:
    tool_search.rs:85
    Tool search result nested name = final ToolInfo.callable_name:
    tool_search.rs:86
    Deferred tool handler is registered as "{namespace}:{name}":
    tool_registry_plan.rs:248
    When a function call comes back, core recombines namespace + name, looks
    up the full qualified key, and gets the raw server/tool for MCP
    execution: codex.rs:4353
    
    **Separate Legacy Snapshot**
    
    collect_mcp_snapshot_from_manager_with_detail() still returns a map
    keyed by qualified callable name.
    mcpServerStatus/list no longer uses that; it uses
    McpServerStatusSnapshot, which is raw-inventory shaped.
  • Forward app-server turn clientMetadata to Responses (#16009)
    ## Summary
    App-server v2 already receives turn-scoped `clientMetadata`, but the
    Rust app-server was dropping it before the outbound Responses request.
    This change keeps the fix lightweight by threading that metadata through
    the existing turn-metadata path rather than inventing a new transport.
    
    ## What we're trying to do and why
    We want turn-scoped metadata from the app-server protocol layer,
    especially fields like Hermes/GAAS run IDs, to survive all the way to
    the actual Responses API request so it is visible in downstream
    websocket request logging and analytics.
    
    The specific bug was:
    - app-server protocol uses camelCase `clientMetadata`
    - Responses transport already has an existing turn metadata carrier:
    `x-codex-turn-metadata`
    - websocket transport already rewrites that header into
    `request.request_body.client_metadata["x-codex-turn-metadata"]`
    - but the Rust app-server never parsed or stored `clientMetadata`, so
    nothing from the app-server request was making it into that existing
    path
    
    This PR fixes that without adding a new header or a second metadata
    channel.
    
    ## How we did it
    ### Protocol surface
    - Add optional `clientMetadata` to v2 `TurnStartParams` and
    `TurnSteerParams`
    - Regenerate the JSON schema / TypeScript fixtures
    - Update app-server docs to describe the field and its behavior
    
    ### Runtime plumbing
    - Add a dedicated core op for app-server user input carrying turn-scoped
    metadata: `Op::UserInputWithClientMetadata`
    - Wire `turn/start` and `turn/steer` through that op / signature path
    instead of dropping the metadata at the message-processor boundary
    - Store the metadata in `TurnMetadataState`
    
    ### Transport behavior
    - Reuse the existing serialized `x-codex-turn-metadata` payload
    - Merge the new app-server `clientMetadata` into that JSON additively
    - Do **not** replace built-in reserved fields already present in the
    turn metadata payload
    - Keep websocket behavior unchanged at the outer shape level: it still
    sends only `client_metadata["x-codex-turn-metadata"]`, but that JSON
    string now contains the merged fields
    - Keep HTTP fallback behavior unchanged except that the existing
    `x-codex-turn-metadata` header now includes the merged fields too
    
    ### Request shape before / after
    Before, a websocket `response.create` looked like:
    ```json
    {
      "type": "response.create",
      "client_metadata": {
        "x-codex-turn-metadata": "{\"session_id\":\"...\",\"turn_id\":\"...\"}"
      }
    }
    ```
    Even if the app-server caller supplied `clientMetadata`, it was not
    represented there.
    
    After, the same request shape is preserved, but the serialized payload
    now includes the new turn-scoped fields:
    ```json
    {
      "type": "response.create",
      "client_metadata": {
        "x-codex-turn-metadata": "{\"session_id\":\"...\",\"turn_id\":\"...\",\"fiber_run_id\":\"fiber-start-123\",\"origin\":\"gaas\"}"
      }
    }
    ```
    
    ## Validation
    ### Targeted tests added / updated
    - protocol round-trip coverage for `clientMetadata` on `turn/start` and
    `turn/steer`
    - protocol round-trip coverage for `Op::UserInputWithClientMetadata`
    - `TurnMetadataState` merge test proving client metadata is added
    without overwriting reserved built-in fields
    - websocket request-shape test proving outbound `response.create`
    contains merged metadata inside
    `client_metadata["x-codex-turn-metadata"]`
    - app-server integration tests proving:
    - `turn/start` forwards `clientMetadata` into the outbound Responses
    request path
      - websocket warmup + real turn request both behave correctly
      - `turn/steer` updates the follow-up request metadata
    
    ### Commands run
    - `just write-app-server-schema`
    - `cargo test -p codex-app-server-protocol`
    - `cargo test -p codex-protocol`
    - `cargo test -p codex-core
    turn_metadata_state_merges_client_metadata_without_replacing_reserved_fields
    --lib`
    - `cargo test -p codex-core --test all
    responses_websocket_preserves_custom_turn_metadata_fields`
    - `cargo test -p codex-app-server --test all client_metadata`
    - `cargo test -p codex-app-server --test all
    turn_start_forwards_client_metadata_to_responses_websocket_request_body_v2
    -- --nocapture`
    - `just fmt`
    - `just fix -p codex-core -p codex-protocol -p codex-app-server-protocol
    -p codex-app-server`
    - `just fix -p codex-exec -p codex-tui-app-server`
    - `just argument-comment-lint`
    
    ### Full suite note
    `cargo test` in `codex-rs` still fails in:
    -
    `suite::v2::turn_interrupt::turn_interrupt_resolves_pending_command_approval_request`
    
    I verified that same failure on a clean detached `HEAD` worktree with an
    isolated `CARGO_TARGET_DIR`, so it is not caused by this patch.
  • remove temporary ownership re-exports (#16626)
    Stacked on #16508.
    
    This removes the temporary `codex-core` / `codex-login` re-export shims
    from the ownership split and rewrites callsites to import directly from
    `codex-model-provider-info`, `codex-models-manager`, `codex-api`,
    `codex-protocol`, `codex-feedback`, and `codex-response-debug-context`.
    
    No behavior change intended; this is the mechanical import cleanup layer
    split out from the ownership move.
    
    ---------
    
    Co-authored-by: Codex <noreply@openai.com>
  • extract models manager and related ownership from core (#16508)
    ## Summary
    - split `models-manager` out of `core` and add `ModelsManagerConfig`
    plus `Config::to_models_manager_config()` so model metadata paths stop
    depending on `core::Config`
    - move login-owned/auth-owned code out of `core` into `codex-login`,
    move model provider config into `codex-model-provider-info`, move API
    bridge mapping into `codex-api`, move protocol-owned types/impls into
    `codex-protocol`, and move response debug helpers into a dedicated
    `response-debug-context` crate
    - move feedback tag emission into `codex-feedback`, relocate tests to
    the crates that now own the code, and keep broad temporary re-exports so
    this PR avoids a giant import-only rewrite
    
    ## Major moves and decisions
    - created `codex-models-manager` as the owner for model
    cache/catalog/config/model info logic, including the new
    `ModelsManagerConfig` struct
    - created `codex-model-provider-info` as the owner for provider config
    parsing/defaults and kept temporary `codex-login`/`codex-core`
    re-exports for old import paths
    - moved `api_bridge` error mapping + `CoreAuthProvider` into
    `codex-api`, while `codex-login::api_bridge` temporarily re-exports
    those symbols and keeps the `auth_provider_from_auth` wrapper
    - moved `auth_env_telemetry` and `provider_auth` ownership to
    `codex-login`
    - moved `CodexErr` ownership to `codex-protocol::error`, plus
    `StreamOutput`, `bytes_to_string_smart`, and network policy helpers to
    protocol-owned modules
    - created `codex-response-debug-context` for
    `extract_response_debug_context`, `telemetry_transport_error_message`,
    and related response-debug plumbing instead of leaving that behavior in
    `core`
    - moved `FeedbackRequestTags`, `emit_feedback_request_tags`, and
    `emit_feedback_request_tags_with_auth_env` to `codex-feedback`
    - deferred removal of temporary re-exports and the mechanical import
    rewrites to a stacked follow-up PR so this PR stays reviewable
    
    ## Test moves
    - moved auth refresh coverage from `core/tests/suite/auth_refresh.rs` to
    `login/tests/suite/auth_refresh.rs`
    - moved text encoding coverage from
    `core/tests/suite/text_encoding_fix.rs` to
    `protocol/src/exec_output_tests.rs`
    - moved model info override coverage from
    `core/tests/suite/model_info_overrides.rs` to
    `models-manager/src/model_info_overrides_tests.rs`
    
    ---------
    
    Co-authored-by: Codex <noreply@openai.com>
  • core: remove cross-crate re-exports from lib.rs (#16512)
    ## Why
    
    `codex-core` was re-exporting APIs owned by sibling `codex-*` crates,
    which made downstream crates depend on `codex-core` as a proxy module
    instead of the actual owner crate.
    
    Removing those forwards makes crate boundaries explicit and lets leaf
    crates drop unnecessary `codex-core` dependencies. In this PR, this
    reduces the dependency on `codex-core` to `codex-login` in the following
    files:
    
    ```
    codex-rs/backend-client/Cargo.toml
    codex-rs/mcp-server/tests/common/Cargo.toml
    ```
    
    ## What
    
    - Remove `codex-rs/core/src/lib.rs` re-exports for symbols owned by
    `codex-login`, `codex-mcp`, `codex-rollout`, `codex-analytics`,
    `codex-protocol`, `codex-shell-command`, `codex-sandboxing`,
    `codex-tools`, and `codex-utils-path`.
    - Delete the `default_client` forwarding shim in `codex-rs/core`.
    - Update in-crate and downstream callsites to import directly from the
    owning `codex-*` crate.
    - Add direct Cargo dependencies where callsites now target the owner
    crate, and remove `codex-core` from `codex-rs/backend-client`.
  • [plugins] Add a flag for tool search. (#15722)
    - [x] Add a flag for tool search.
  • Split features into codex-features crate (#15253)
    - Split the feature system into a new `codex-features` crate.
    - Cut `codex-core` and workspace consumers over to the new config and
    warning APIs.
    
    Co-authored-by: Ahmed Ibrahim <219906144+aibrahim-oai@users.noreply.github.com>
    Co-authored-by: Codex <noreply@openai.com>
  • Plumb MCP turn metadata through _meta (#15190)
    ## Summary
    
    Some background. We're looking to instrument GA turns end to end. Right
    now a big gap is grouping mcp tool calls with their codex sessions. We
    send session id and turn id headers to the responses call but not the
    mcp/wham calls.
    
    Ideally we could pass the args as headers like with responses, but given
    the setup of the rmcp client, we can't send as headers without either
    changing the rmcp package upstream to allow per request headers or
    introducing a mutex which break concurrency. An earlier attempt made the
    assumption that we had 1 client per thread, which allowed us to set
    headers at the start of a turn. @pakrym mentioned that this assumption
    might break in the near future.
    
    So the solution now is to package the turn metadata/session id into the
    _meta field in the post body and pull out in codex-backend.
    
    - send turn metadata to MCP servers via `tools/call` `_meta` instead of
    assuming per-thread request headers on shared clients
    - preserve the existing `_codex_apps` metadata while adding
    `x-codex-turn-metadata` for all MCP tool calls
    - extend tests to cover both custom MCP servers and the codex apps
    search flow
    
    ---------
    
    Co-authored-by: Codex <noreply@openai.com>
  • [apps] Improve search tool fallback. (#14732)
    - [x] Bypass tool search and stuff tool specs directly into model
    context when either a. Tool search is not available for the model or b.
    There are not that many tools to search for.
  • [apps] Add tool call meta. (#14647)
    - [x] Add resource_uri and other things to _meta to shortcut resource
    lookup and speed things up.
  • Normalize MCP tool names to code-mode safe form (#14605)
    Code mode doesn't allow `-` in names and it's better if function names
    and code-mode names are the same.
  • feat: search_tool migrate to bring you own tool of Responses API (#14274)
    ## Why
    
    to support a new bring your own search tool in Responses
    API(https://developers.openai.com/api/docs/guides/tools-tool-search#client-executed-tool-search)
    we migrating our bm25 search tool to use official way to execute search
    on client and communicate additional tools to the model.
    
    ## What
    - replace the legacy `search_tool_bm25` flow with client-executed
    `tool_search`
    - add protocol, SSE, history, and normalization support for
    `tool_search_call` and `tool_search_output`
    - return namespaced Codex Apps search results and wire namespaced
    follow-up tool calls back into MCP dispatch
  • [apps] Fix apps enablement condition. (#14011)
    - [x] Fix apps enablement condition to check both the feature flag and
    that the user is not an API key user.
  • add @plugin mentions (#13510)
    ## Note-- added plugin mentions via @, but that conflicts with file
    mentions
    
    depends and builds upon #13433.
    
    - introduces explicit `@plugin` mentions. this injects the plugin's mcp
    servers, app names, and skill name format into turn context as a dev
    message.
    - we do not yet have UI for these mentions, so we currently parse raw
    text (as opposed to skills and apps which have UI chips, autocomplete,
    etc.) this depends on a `plugins/list` app-server endpoint we can feed
    the UI with, which is upcoming
    - also annotate mcp and app tool descriptions with the plugin(s) they
    come from. this gives the model a first class way of understanding what
    tools come from which plugins, which will help implicit invocation.
    
    ### Tests
    Added and updated tests, unit and integration. Also confirmed locally a
    raw `@plugin` injects the dev message, and the model knows about its
    apps, mcps, and skills.
  • config: enforce enterprise feature requirements (#13388)
    ## Why
    
    Enterprises can already constrain approvals, sandboxing, and web search
    through `requirements.toml` and MDM, but feature flags were still only
    configurable as managed defaults. That meant an enterprise could suggest
    feature values, but it could not actually pin them.
    
    This change closes that gap and makes enterprise feature requirements
    behave like the other constrained settings. The effective feature set
    now stays consistent with enterprise requirements during config load,
    when config writes are validated, and when runtime code mutates feature
    flags later in the session.
    
    It also tightens the runtime API for managed features. `ManagedFeatures`
    now follows the same constraint-oriented shape as `Constrained<T>`
    instead of exposing panic-prone mutation helpers, and production code
    can no longer construct it through an unconstrained `From<Features>`
    path.
    
    The PR also hardens the `compact_resume_fork` integration coverage on
    Windows. After the feature-management changes,
    `compact_resume_after_second_compaction_preserves_history` was
    overflowing the libtest/Tokio thread stacks on Windows, so the test now
    uses an explicit larger-stack harness as a pragmatic mitigation. That
    may not be the ideal root-cause fix, and it merits a parallel
    investigation into whether part of the async future chain should be
    boxed to reduce stack pressure instead.
    
    ## What Changed
    
    Enterprises can now pin feature values in `requirements.toml` with the
    requirements-side `features` table:
    
    ```toml
    [features]
    personality = true
    unified_exec = false
    ```
    
    Only canonical feature keys are allowed in the requirements `features`
    table; omitted keys remain unconstrained.
    
    - Added a requirements-side pinned feature map to
    `ConfigRequirementsToml`, threaded it through source-preserving
    requirements merge and normalization in `codex-config`, and made the
    TOML surface use `[features]` (while still accepting legacy
    `[feature_requirements]` for compatibility).
    - Exposed `featureRequirements` from `configRequirements/read`,
    regenerated the JSON/TypeScript schema artifacts, and updated the
    app-server README.
    - Wrapped the effective feature set in `ManagedFeatures`, backed by
    `ConstrainedWithSource<Features>`, and changed its API to mirror
    `Constrained<T>`: `can_set(...)`, `set(...) -> ConstraintResult<()>`,
    and result-returning `enable` / `disable` / `set_enabled` helpers.
    - Removed the legacy-usage and bulk-map passthroughs from
    `ManagedFeatures`; callers that need those behaviors now mutate a plain
    `Features` value and reapply it through `set(...)`, so the constrained
    wrapper remains the enforcement boundary.
    - Removed the production loophole for constructing unconstrained
    `ManagedFeatures`. Non-test code now creates it through the configured
    feature-loading path, and `impl From<Features> for ManagedFeatures` is
    restricted to `#[cfg(test)]`.
    - Rejected legacy feature aliases in enterprise feature requirements,
    and return a load error when a pinned combination cannot survive
    dependency normalization.
    - Validated config writes against enterprise feature requirements before
    persisting changes, including explicit conflicting writes and
    profile-specific feature states that normalize into invalid
    combinations.
    - Updated runtime and TUI feature-toggle paths to use the constrained
    setter API and to persist or apply the effective post-constraint value
    rather than the requested value.
    - Updated the `core_test_support` Bazel target to include the bundled
    core model-catalog fixtures in its runtime data, so helper code that
    resolves `core/models.json` through runfiles works in remote Bazel test
    environments.
    - Renamed the core config test coverage to emphasize that effective
    feature values are normalized at runtime, while conflicting persisted
    config writes are rejected.
    - Ran `compact_resume_after_second_compaction_preserves_history` inside
    an explicit 8 MiB test thread and Tokio runtime worker stack, following
    the existing larger-stack integration-test pattern, to keep the Windows
    `compact_resume_fork` test slice from aborting while a parallel
    investigation continues into whether some of the underlying async
    futures should be boxed.
    
    ## Verification
    
    - `cargo test -p codex-config`
    - `cargo test -p codex-core feature_requirements_ -- --nocapture`
    - `cargo test -p codex-core
    load_requirements_toml_produces_expected_constraints -- --nocapture`
    - `cargo test -p codex-core
    compact_resume_after_second_compaction_preserves_history -- --nocapture`
    - `cargo test -p codex-core compact_resume_fork -- --nocapture`
    - Re-ran the built `codex-core` `tests/all` binary with
    `RUST_MIN_STACK=262144` for
    `compact_resume_after_second_compaction_preserves_history` to confirm
    the explicit-stack harness fixes the deterministic low-stack repro.
    - `cargo test -p codex-core`
    - This still fails locally in unrelated integration areas that expect
    the `codex` / `test_stdio_server` binaries or hit existing `search_tool`
    wiremock mismatches.
    
    ## Docs
    
    `developers.openai.com/codex` should document the requirements-side
    `[features]` table for enterprise and MDM-managed configuration,
    including that it only accepts canonical feature keys and that
    conflicting config writes are rejected.
  • Add oauth_resource handling for MCP login flows (#12866)
    Addresses bug https://github.com/openai/codex/issues/12589
    
    Builds on community PR #12763.
    
    This adds `oauth_resource` support for MCP `streamable_http` servers and
    wires it through the relevant config and login paths. It fixes the bug
    where the configured OAuth resource was not reliably included in the
    authorization request, causing MCP login to omit the expected
    `resource` parameter.
  • chore: remove codex-core public protocol/shell re-exports (#12432)
    ## Why
    
    `codex-rs/core/src/lib.rs` re-exported a broad set of types and modules
    from `codex-protocol` and `codex-shell-command`. That made it easy for
    workspace crates to import those APIs through `codex-core`, which in
    turn hides dependency edges and makes it harder to reduce compile-time
    coupling over time.
    
    This change removes those public re-exports so call sites must import
    from the source crates directly. Even when a crate still depends on
    `codex-core` today, this makes dependency boundaries explicit and
    unblocks future work to drop `codex-core` dependencies where possible.
    
    ## What Changed
    
    - Removed public re-exports from `codex-rs/core/src/lib.rs` for:
    - `codex_protocol::protocol` and related protocol/model types (including
    `InitialHistory`)
      - `codex_protocol::config_types` (`protocol_config_types`)
    - `codex_shell_command::{bash, is_dangerous_command, is_safe_command,
    parse_command, powershell}`
    - Migrated workspace Rust call sites to import directly from:
      - `codex_protocol::protocol`
      - `codex_protocol::config_types`
      - `codex_protocol::models`
      - `codex_shell_command`
    - Added explicit `Cargo.toml` dependencies (`codex-protocol` /
    `codex-shell-command`) in crates that now import those crates directly.
    - Kept `codex-core` internal modules compiling by using `pub(crate)`
    aliases in `core/src/lib.rs` (internal-only, not part of the public
    API).
    - Updated the two utility crates that can already drop a `codex-core`
    dependency edge entirely:
      - `codex-utils-approval-presets`
      - `codex-utils-cli`
    
    ## Verification
    
    - `cargo test -p codex-utils-approval-presets`
    - `cargo test -p codex-utils-cli`
    - `cargo check --workspace --all-targets`
    - `just clippy`
  • feat: persist and restore codex app's tools after search (#11780)
    ### What changed
    1. Removed per-turn MCP selection reset in `core/src/tasks/mod.rs`.
    2. Added `SessionState::set_mcp_tool_selection(Vec<String>)` in
    `core/src/state/session.rs` for authoritative restore behavior (deduped,
    order-preserving, empty clears).
    3. Added rollout parsing in `core/src/codex.rs` to recover
    `active_selected_tools` from prior `search_tool_bm25` outputs:
       - tracks matching `call_id`s
       - parses function output text JSON
       - extracts `active_selected_tools`
       - latest valid payload wins
       - malformed/non-matching payloads are ignored
    4. Applied restore logic to resumed and forked startup paths in
    `core/src/codex.rs`.
    5. Updated instruction text to session/thread scope in
    `core/templates/search_tool/tool_description.md`.
    6. Expanded tests in `core/tests/suite/search_tool.rs`, plus unit
    coverage in:
       - `core/src/codex.rs`
       - `core/src/state/session.rs`
    
    ### Behavior after change
    1. Search activates matched tools.
    2. Additional searches union into active selection.
    3. Selection survives new turns in the same thread.
    4. Resume/fork restores selection from rollout history.
    5. Separate threads do not inherit selection unless forked.
  • core: limit search_tool_bm25 to Apps and clarify discovery guidance (#11669)
    ## Summary
    - Limit `search_tool_bm25` indexing to `codex_apps` tools only, so
    non-Apps MCP servers are no longer discoverable through this search
    path.
    - Move search-tool discovery guidance into the `search_tool_bm25` tool
    description (via template include) instead of injecting it as a separate
    developer message.
    - Update Apps discovery guidance wording to clarify when to use
    `search_tool_bm25` for Apps-backed systems (for example Slack, Google
    Drive, Jira, Notion) and when to call tools directly.
    - Remove dead `core` helper code (`filter_codex_apps_mcp_tools` and
    `codex_apps_connector_id`) that is no longer used after the
    tool-selection refactor.
    - Update `core` search-tool tests to assert codex-apps-only behavior and
    to validate guidance from the tool description.
    
    ## Validation
    -  `just fmt`
    -  `cargo test -p codex-core search_tool`
    - ⚠️ `cargo test -p codex-core` was attempted, but the run repeatedly
    stalled on
    `tools::js_repl::tests::js_repl_can_attach_image_via_view_image_tool`.
    
    ## Tickets
    - None
  • Consolidate search_tool feature into apps (#11509)
    ## Summary
    - Remove `Feature::SearchTool` and the `search_tool` config key from the
    feature registry/schema.
    - Gate `search_tool_bm25` exposure via `Feature::Apps` in
    `core/src/tools/spec.rs`.
    - Update MCP selection logic in `core/src/codex.rs` to use
    `Feature::Apps` for search-tool behavior.
    - Update `core/tests/suite/search_tool.rs` to enable `Feature::Apps`.
    - Regenerate `core/config.schema.json` via `just write-config-schema`.
    
    ## Testing
    - `just fmt`
    - `cargo test -p codex-core --test all suite::search_tool::`
    
    ## Tickets
    - None
  • feat: search_tool (#10657)
    **Why We Did This**
    - The goal is to reduce MCP tool context pollution by not exposing the
    full MCP tool list up front
    - It forces an explicit discovery step (`search_tool_bm25`) so the model
    narrows tool scope before making MCP calls, which helps relevance and
    lowers prompt/tool clutter.
    
    **What It Changed**
    - Added a new experimental feature flag `search_tool` in
    `core/src/features.rs:90` and `core/src/features.rs:430`.
    - Added config/schema support for that flag in
    `core/config.schema.json:214` and `core/config.schema.json:1235`.
    - Added BM25 dependency (`bm25`) in `Cargo.toml:129` and
    `core/Cargo.toml:23`.
    - Added new tool handler `search_tool_bm25` in
    `core/src/tools/handlers/search_tool_bm25.rs:18`.
    - Registered the handler and tool spec in
    `core/src/tools/handlers/mod.rs:11` and `core/src/tools/spec.rs:780` and
    `core/src/tools/spec.rs:1344`.
    - Extended `ToolsConfig` to carry `search_tool` enablement in
    `core/src/tools/spec.rs:32` and `core/src/tools/spec.rs:56`.
    - Injected dedicated developer instructions for tool-discovery workflow
    in `core/src/codex.rs:483` and `core/src/codex.rs:1976`, using
    `core/templates/search_tool/developer_instructions.md:1`.
    - Added session state to store one-shot selected MCP tools in
    `core/src/state/session.rs:27` and `core/src/state/session.rs:131`.
    - Added filtering so when feature is enabled, only selected MCP tools
    are exposed on the next request (then consumed) in
    `core/src/codex.rs:3800` and `core/src/codex.rs:3843`.
    - Added E2E suite coverage for
    enablement/instructions/hide-until-search/one-turn-selection in
    `core/tests/suite/search_tool.rs:72`,
    `core/tests/suite/search_tool.rs:109`,
    `core/tests/suite/search_tool.rs:147`, and
    `core/tests/suite/search_tool.rs:218`.
    - Refactored test helper utilities to support config-driven tool
    collection in `core/tests/suite/tools.rs:281`.
    
    **Net Behavioral Effect**
    - With `search_tool` **off**: existing MCP behavior (tools exposed
    normally).
    - With `search_tool` **on**: MCP tools start hidden, model must call
    `search_tool_bm25`, and only returned `selected_tools` are available for
    the next model call.