**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.
## Summary
- add shared `ModeKind` helpers for display names, TUI visibility, and
`request_user_input` availability
- derive TUI mode filtering/labels from shared `ModeKind` metadata
instead of local hardcoded matches
- derive `request_user_input` availability text and unavailable error
mode names from shared mode metadata
- replace hardcoded known mode names in the Default collaboration-mode
template with `{{KNOWN_MODE_NAMES}}` and fill it from
`TUI_VISIBLE_COLLABORATION_MODES`
- add regression tests for mode metadata sync and placeholder
replacement
## Notes
- `cargo test -p codex-core` integration target (`tests/all`) still
shows pre-existing env-specific failures in this environment due missing
`test_stdio_server` binary resolution; core unit tests are green.
## Codex author
`codex resume 019c26ff-dfe7-7173-bc04-c9e1fff1e447`
## Summary
This PR updates `request_user_input` behavior and Default-mode guidance
to match current collaboration-mode semantics and reduce model
confusion.
## Why
- `request_user_input` should be explicitly documented as **Plan-only**.
- Tool description and runtime availability checks should be driven by
the **same centralized mode policy**.
- Default mode prompt needed stronger execution guidance and explicit
instruction that `request_user_input` is unavailable.
- Error messages should report the **actual mode name** (not aliases
that can read as misleading).
## What changed
- Centralized `request_user_input` mode policy in `core` handler logic:
- Added a single allowed-modes config (`Plan` only).
- Reused that policy for:
- runtime rejection messaging
- tool description text
- Updated tool description to include availability constraint:
- `"This tool is only available in Plan mode."`
- Updated runtime rejection behavior:
- `Default` -> `"request_user_input is unavailable in Default mode"`
- `Execute` -> `"request_user_input is unavailable in Execute mode"`
- `PairProgramming` -> `"request_user_input is unavailable in Pair
Programming mode"`
- Strengthened Default collaboration prompt:
- Added explicit execution-first behavior
- Added assumptions-first guidance
- Added explicit `request_user_input` unavailability instruction
- Added concise progress-reporting expectations
- Simplified formatting implementation:
- Inlined allowed-mode name collection into `format_allowed_modes()`
- Kept `format_allowed_modes()` output for 3+ modes as CSV style
(`modes: a,b,c`)
## Summary
This PR simplifies collaboration modes to the visible set `default |
plan`, while preserving backward compatibility for older partners that
may still send legacy mode
names.
Specifically:
- Renames the old Code behavior to **Default**.
- Keeps **Plan** as-is.
- Removes **Custom** mode behavior (fallbacks now resolve to Default).
- Keeps `PairProgramming` and `Execute` internally for compatibility
plumbing, while removing them from schema/API and UI visibility.
- Adds legacy input aliasing so older clients can still send old mode
names.
## What Changed
1. Mode enum and compatibility
- `ModeKind` now uses `Plan` + `Default` as active/public modes.
- `ModeKind::Default` deserialization accepts legacy values:
- `code`
- `pair_programming`
- `execute`
- `custom`
- `PairProgramming` and `Execute` variants remain in code but are hidden
from protocol/schema generation.
- `Custom` variant is removed; previous custom fallbacks now map to
`Default`.
2. Collaboration presets and templates
- Built-in presets now return only:
- `Plan`
- `Default`
- Template rename:
- `core/templates/collaboration_mode/code.md` -> `default.md`
- `execute.md` and `pair_programming.md` remain on disk but are not
surfaced in visible preset lists.
3. TUI updates
- Updated user-facing naming and prompts from “Code” to “Default”.
- Updated mode-cycle and indicator behavior to reflect only visible
`Plan` and `Default`.
- Updated corresponding tests and snapshots.
4. request_user_input behavior
- `request_user_input` remains allowed only in `Plan` mode.
- Rejection messaging now consistently treats non-plan modes as
`Default`.
5. Schemas
- Regenerated config and app-server schemas.
- Public schema types now advertise mode values as:
- `plan`
- `default`
## Backward Compatibility Notes
- Incoming legacy mode names (`code`, `pair_programming`, `execute`,
`custom`) are accepted and coerced to `default`.
- Outgoing/public schema surfaces intentionally expose only `plan |
default`.
- This allows tolerant ingestion of older partner payloads while
standardizing new integrations on the reduced mode set.
## Codex author
`codex fork 019c1fae-693b-7840-b16e-9ad38ea0bd00`
## Summary
- Replace the “Hard interaction rule” with a clearer “Response
constraints” section that enumerates the allowed exceptions for Plan
Mode replies.
- Remove the stray Phase 1 exception line about simple questions.
- Update plan content requirements to ask for a brief summary section
and generalize API/type wording.
# External (non-OpenAI) Pull Request Requirements
Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
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If your PR conforms to our contribution guidelines, replace this text
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Include a link to a bug report or enhancement request.
# External (non-OpenAI) Pull Request Requirements
Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
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If your PR conforms to our contribution guidelines, replace this text
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# External (non-OpenAI) Pull Request Requirements
Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
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If your PR conforms to our contribution guidelines, replace this text
with a detailed and high quality description of your changes.
Include a link to a bug report or enhancement request.
## Summary
- Stream proposed plans in Plan Mode using `<proposed_plan>` tags parsed
in core, emitting plan deltas plus a plan `ThreadItem`, while stripping
tags from normal assistant output.
- Persist plan items and rebuild them on resume so proposed plans show
in thread history.
- Wire plan items/deltas through app-server protocol v2 and render a
dedicated proposed-plan view in the TUI, including the “Implement this
plan?” prompt only when a plan item is present.
## Changes
### Core (`codex-rs/core`)
- Added a generic, line-based tag parser that buffers each line until it
can disprove a tag prefix; implements auto-close on `finish()` for
unterminated tags. `codex-rs/core/src/tagged_block_parser.rs`
- Refactored proposed plan parsing to wrap the generic parser.
`codex-rs/core/src/proposed_plan_parser.rs`
- In plan mode, stream assistant deltas as:
- **Normal text** → `AgentMessageContentDelta`
- **Plan text** → `PlanDelta` + `TurnItem::Plan` start/completion
(`codex-rs/core/src/codex.rs`)
- Final plan item content is derived from the completed assistant
message (authoritative), not necessarily the concatenated deltas.
- Strips `<proposed_plan>` blocks from assistant text in plan mode so
tags don’t appear in normal messages.
(`codex-rs/core/src/stream_events_utils.rs`)
- Persist `ItemCompleted` events only for plan items for rollout replay.
(`codex-rs/core/src/rollout/policy.rs`)
- Guard `update_plan` tool in Plan Mode with a clear error message.
(`codex-rs/core/src/tools/handlers/plan.rs`)
- Updated Plan Mode prompt to:
- keep `<proposed_plan>` out of non-final reasoning/preambles
- require exact tag formatting
- allow only one `<proposed_plan>` block per turn
(`codex-rs/core/templates/collaboration_mode/plan.md`)
### Protocol / App-server protocol
- Added `TurnItem::Plan` and `PlanDeltaEvent` to core protocol items.
(`codex-rs/protocol/src/items.rs`, `codex-rs/protocol/src/protocol.rs`)
- Added v2 `ThreadItem::Plan` and `PlanDeltaNotification` with
EXPERIMENTAL markers and note that deltas may not match the final plan
item. (`codex-rs/app-server-protocol/src/protocol/v2.rs`)
- Added plan delta route in app-server protocol common mapping.
(`codex-rs/app-server-protocol/src/protocol/common.rs`)
- Rebuild plan items from persisted `ItemCompleted` events on resume.
(`codex-rs/app-server-protocol/src/protocol/thread_history.rs`)
### App-server
- Forward plan deltas to v2 clients and map core plan items to v2 plan
items. (`codex-rs/app-server/src/bespoke_event_handling.rs`,
`codex-rs/app-server/src/codex_message_processor.rs`)
- Added v2 plan item tests.
(`codex-rs/app-server/tests/suite/v2/plan_item.rs`)
### TUI
- Added a dedicated proposed plan history cell with special background
and padding, and moved “• Proposed Plan” outside the highlighted block.
(`codex-rs/tui/src/history_cell.rs`, `codex-rs/tui/src/style.rs`)
- Only show “Implement this plan?” when a plan item exists.
(`codex-rs/tui/src/chatwidget.rs`,
`codex-rs/tui/src/chatwidget/tests.rs`)
<img width="831" height="847" alt="Screenshot 2026-01-29 at 7 06 24 PM"
src="https://github.com/user-attachments/assets/69794c8c-f96b-4d36-92ef-c1f5c3a8f286"
/>
### Docs / Misc
- Updated protocol docs to mention plan deltas.
(`codex-rs/docs/protocol_v1.md`)
- Minor plumbing updates in exec/debug clients to tolerate plan deltas.
(`codex-rs/debug-client/src/reader.rs`, `codex-rs/exec/...`)
## Tests
- Added core integration tests:
- Plan mode strips plan from agent messages.
- Missing `</proposed_plan>` closes at end-of-message.
(`codex-rs/core/tests/suite/items.rs`)
- Added unit tests for generic tag parser (prefix buffering, non-tag
lines, auto-close). (`codex-rs/core/src/tagged_block_parser.rs`)
- Existing app-server plan item tests in v2.
(`codex-rs/app-server/tests/suite/v2/plan_item.rs`)
## Notes / Behavior
- Plan output no longer appears in standard assistant text in Plan Mode;
it streams via `PlanDelta` and completes as a `TurnItem::Plan`.
- The final plan item content is authoritative and may diverge from
streamed deltas (documented as experimental).
- Reasoning summaries are not filtered; prompt instructs the model not
to include `<proposed_plan>` outside the final plan message.
## Codex Author
`codex fork 019bec2d-b09d-7450-b292-d7bcdddcdbfb`
## Summary
- Tightens Plan Mode to encourage exploration-first behavior and more
back-and-forth alignment.
- Adds a required TL;DR checkpoint before drafting the full plan.
- Clarifies client behavior that can cause premature “Implement this
plan?” prompts.
## What changed
- Require at least one targeted non-mutating exploration pass before the
first user question.
- Insert a TL;DR checkpoint between Phase 2 (intent) and Phase 3
(implementation).
- TL;DR checkpoint guidance:
- Label: “Proposed Plan (TL;DR)”
- Format: 3–5 bullets using `- `
- Options: exactly one option, “Approve”
- `isOther: true`, with explicit guidance that “None of the above” is
the edit path in the current UI.
- Require the final plan to include a TL;DR consistent with the approved
checkpoint.
## Why
- In Plan Mode, any normal assistant message at turn completion is
treated as plan content by the client. This can trigger premature
“Implement this plan?” prompts.
- The TL;DR checkpoint aligns on direction before Codex drafts a long,
decision-complete plan.
## Testing
- Manual: built the local CLI and verified the flow now explores first,
presents a TL;DR checkpoint, and only drafts the full plan after
approval.
---------
Co-authored-by: Nick Baumann <@openai.com>
## Summary
Let's dial in this api contract in a bit more with more robust fallback
behavior when model_instructions_template is false.
Switches to a more explicit template / variables structure, with more
fallbacks.
## Testing
- [x] Adding unit tests
- [x] Tested locally
## Summary
Add personality instructions so we can let users try it out, in tandem
with making it an experimental feature
## Testing
- [x] Tested locally
# External (non-OpenAI) Pull Request Requirements
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# External (non-OpenAI) Pull Request Requirements
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# External (non-OpenAI) Pull Request Requirements
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# External (non-OpenAI) Pull Request Requirements
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# External (non-OpenAI) Pull Request Requirements
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# External (non-OpenAI) Pull Request Requirements
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Reproduce with a prompt like this with collab enabled:
```
Examine the code at <some subdirectory with a deeply nested project>. Find the most urgent issue to resolve and describe it to me.
```
Existing behavior causes the top-level agent to busy wait on subagents.
# External (non-OpenAI) Pull Request Requirements
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Include a link to a bug report or enhancement request.
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## Summary
Introduces the concept of a config model_personality. I would consider
this an MVP for testing out the feature. There are a number of
follow-ups to this PR:
- More sophisticated templating with validation
- In-product experience to manage this
## Testing
- [x] Testing locally
### Summary
* Added instruction on using `request_user_input`
* Added the output to be json with `plan` key and the actual plan as the
value.
* Remove `PLAN.md` write because that gets into sandbox issue. We can
add it back later.
# External (non-OpenAI) Pull Request Requirements
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Adding a prompt for collab tools. This is only for internal use and the
prompt won't be gated for now as it is not stable yet.
The goal of this PR is to provide the tool required to iterate on the
prompt
This PR does the following:
- Add compact prefix to the summary
- Change the compaction prompt
- Allow multiple compaction for long running tasks
- Filter out summary messages on the following compaction
Considerations:
- Filtering out the summary message isn't the most clean
- Theoretically, we can end up in infinite compaction loop if the user
messages > compaction limit . However, that's not possible in today's
code because we have hard cap on user messages.
- We need to address having multiple user messages because it confuses
the model.
Testing:
- Making sure that after compact we always end up with one user message
(task) and one summary, even on multiple compaction.
* Removed sandbox risk categories; feedback indicates that these are not
that useful and "less is more"
* Tweaked the assessment prompt to generate terser answers
* Fixed bug in orchestrator that prevents this feature from being
exposed in the extension
