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codex/codex-rs
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Felipe Coury 79359fb5e7 fix(tui_app_server): fix remote subagent switching and agent names (#15513)
## TL;DR

This PR changes the `tui_app_server` _path_ in the following ways:

- add missing feature to show agent names (shows only UUIDs today) 
- add `Cmd/Alt+Arrows` navigation between agent conversations

## Problem

When the TUI connects to a remote app server, collab agent tool-call
items (spawn, wait, delegate, etc.) render thread UUIDs instead of
human-readable agent names because the `ChatWidget` never receives
nickname/role metadata for receiver threads. Separately, keyboard
next/previous agent navigation silently does nothing when the local
`AgentNavigationState` cache has not yet been populated with subagent
threads that the remote server already knows about.

Both issues share a root cause: in the remote (app-server) code path the
TUI never proactively fetches thread metadata. In the local code path
this metadata arrives naturally via spawn events the TUI itself
orchestrates, but in the remote path those events were processed by a
different client and the TUI only sees the resulting collab tool-call
notifications.

## Mental model

Collab agent tool-call notifications reference receiver threads by id,
but carry no nickname or role. The TUI needs that metadata in two
places:

1. **Rendering** -- `ChatWidget` converts `CollabAgentToolCall` items
into history cells. Without metadata, agent status lines show raw UUIDs.
2. **Navigation** -- `AgentNavigationState` tracks known threads for the
`/agent` picker and keyboard cycling. Without entries for remote
subagents, next/previous has nowhere to go.

This change closes the gap with two complementary strategies:

- **Eager hydration**: when any notification carries
`receiver_thread_ids`, the TUI fetches metadata (`thread/read`) for
threads it has not yet cached before the notification is rendered.
- **Backfill on thread switch**: when the user resumes, forks, or starts
a new app-server thread, the TUI fetches the full `thread/loaded/list`,
walks the parent-child spawn tree, and registers every descendant
subagent in both the navigation cache and the `ChatWidget` metadata map.

A new `collab_agent_metadata` side-table in `ChatWidget` stores
nickname/role keyed by `ThreadId`, kept in sync by `App` whenever it
calls `upsert_agent_picker_thread`. The `replace_chat_widget` helper
re-seeds this map from `AgentNavigationState` so that thread switches
(which reconstruct the widget) do not lose previously discovered
metadata.

## Non-goals

- This change does not alter the local (non-app-server) collab code
path. That path already receives metadata via spawn events and is
unaffected.
- No new protocol messages are introduced. The change uses existing
`thread/read` and `thread/loaded/list` RPCs.
- No changes to how `AgentNavigationState` orders or cycles through
threads. The traversal logic is unchanged; only the population of
entries is extended.

## Tradeoffs

- **Extra RPCs on notification path**:
`hydrate_collab_agent_metadata_for_notification` issues a `thread/read`
for each unknown receiver thread before the notification is forwarded to
rendering. This adds latency on the notification path but only fires
once per thread (the result is cached). The alternative -- rendering
first and backfilling names later -- would cause visible flicker as
UUIDs are replaced with names.
- **Backfill fetches all loaded threads**:
`backfill_loaded_subagent_threads` fetches the full loaded-thread list
and walks the spawn tree even when the user may only care about one
subagent. This is simple and correct but O(loaded_threads) per thread
switch. For typical session sizes this is negligible; it could become a
concern for sessions with hundreds of subagents.
- **Metadata duplication**: agent nickname/role is now stored in both
`AgentNavigationState` (for picker/label) and
`ChatWidget::collab_agent_metadata` (for rendering). The two are kept in
sync through `upsert_agent_picker_thread` and `replace_chat_widget`, but
there is no compile-time enforcement of this coupling.

## Architecture

### New module: `app::loaded_threads`

Pure function `find_loaded_subagent_threads_for_primary` that takes a
flat list of `Thread` objects and a primary thread id, then walks the
`SessionSource::SubAgent` parent-child edges to collect all transitive
descendants. Returns a sorted vec of `LoadedSubagentThread` (thread_id +
nickname + role). No async, no side effects -- designed for unit
testing.

### New methods on `App`

| Method | Purpose |
|--------|---------|
| `collab_receiver_thread_ids` | Extracts `receiver_thread_ids` from
`ItemStarted` / `ItemCompleted` collab notifications |
| `hydrate_collab_agent_metadata_for_notification` | Fetches and caches
metadata for unknown receiver threads before a notification is rendered
|
| `backfill_loaded_subagent_threads` | Bulk-fetches all loaded threads
and registers descendants of the primary thread |
| `adjacent_thread_id_with_backfill` | Attempts navigation, falls back
to backfill if the cache has no adjacent entry |
| `replace_chat_widget` | Replaces the widget and re-seeds its metadata
map from `AgentNavigationState` |

### New state in `ChatWidget`

`collab_agent_metadata: HashMap<ThreadId, CollabAgentMetadata>` -- a
lookup table that rendering functions consult to attach human-readable
names to collab tool-call items. Populated externally by `App` via
`set_collab_agent_metadata`.

### New method on `AppServerSession`

`thread_loaded_list` -- thin wrapper around
`ClientRequest::ThreadLoadedList`.

## Observability

- `tracing::warn` on invalid thread ids during hydration and backfill.
- `tracing::warn` on failed `thread/read` or `thread/loaded/list` RPCs
(with thread id and error).
- No new metrics or feature flags.

## Tests

-
**`loaded_threads::tests::finds_loaded_subagent_tree_for_primary_thread`**
-- unit test for the spawn-tree walk: verifies child and grandchild are
included, unrelated threads are excluded, and metadata is carried
through.
-
**`app::tests::replace_chat_widget_reseeds_collab_agent_metadata_for_replay`**
-- integration test that creates a `ChatWidget`, replaces it via
`replace_chat_widget`, replays a collab wait notification, and asserts
the rendered history cell contains the agent name rather than a UUID.
- **Updated snapshot** `app_server_collab_wait_items_render_history` --
the existing collab wait rendering test now sets metadata before sending
notifications, so the snapshot shows `Robie [explorer]` / `Ada
[reviewer]` instead of raw thread ids.

---------

Co-authored-by: Eric Traut <etraut@openai.com>
79359fb5e7 · 2026-03-25 12:50:42 -06:00
History
..
2026-02-25 20:59:07 -08:00
2026-03-20 23:36:58 -07:00
2026-03-25 13:34:43 +00:00

Codex CLI (Rust Implementation)

We provide Codex CLI as a standalone, native executable to ensure a zero-dependency install.

Installing Codex

Today, the easiest way to install Codex is via npm:

npm i -g @openai/codex
codex

You can also install via Homebrew (brew install --cask codex) or download a platform-specific release directly from our GitHub Releases.

Documentation quickstart

What's new in the Rust CLI

The Rust implementation is now the maintained Codex CLI and serves as the default experience. It includes a number of features that the legacy TypeScript CLI never supported.

Config

Codex supports a rich set of configuration options. Note that the Rust CLI uses config.toml instead of config.json. See docs/config.md for details.

Model Context Protocol Support

MCP client

Codex CLI functions as an MCP client that allows the Codex CLI and IDE extension to connect to MCP servers on startup. See the configuration documentation for details.

MCP server (experimental)

Codex can be launched as an MCP server by running codex mcp-server. This allows other MCP clients to use Codex as a tool for another agent.

Use the @modelcontextprotocol/inspector to try it out:

npx @modelcontextprotocol/inspector codex mcp-server

Use codex mcp to add/list/get/remove MCP server launchers defined in config.toml, and codex mcp-server to run the MCP server directly.

Notifications

You can enable notifications by configuring a script that is run whenever the agent finishes a turn. The notify documentation includes a detailed example that explains how to get desktop notifications via terminal-notifier on macOS. When Codex detects that it is running under WSL 2 inside Windows Terminal (WT_SESSION is set), the TUI automatically falls back to native Windows toast notifications so approval prompts and completed turns surface even though Windows Terminal does not implement OSC 9.

codex exec to run Codex programmatically/non-interactively

To run Codex non-interactively, run codex exec PROMPT (you can also pass the prompt via stdin) and Codex will work on your task until it decides that it is done and exits. Output is printed to the terminal directly. You can set the RUST_LOG environment variable to see more about what's going on. Use codex exec --ephemeral ... to run without persisting session rollout files to disk.

Experimenting with the Codex Sandbox

To test to see what happens when a command is run under the sandbox provided by Codex, we provide the following subcommands in Codex CLI:

# macOS
codex sandbox macos [--full-auto] [--log-denials] [COMMAND]...

# Linux
codex sandbox linux [--full-auto] [COMMAND]...

# Windows
codex sandbox windows [--full-auto] [COMMAND]...

# Legacy aliases
codex debug seatbelt [--full-auto] [--log-denials] [COMMAND]...
codex debug landlock [--full-auto] [COMMAND]...

Selecting a sandbox policy via --sandbox

The Rust CLI exposes a dedicated --sandbox (-s) flag that lets you pick the sandbox policy without having to reach for the generic -c/--config option:

# Run Codex with the default, read-only sandbox
codex --sandbox read-only

# Allow the agent to write within the current workspace while still blocking network access
codex --sandbox workspace-write

# Danger! Disable sandboxing entirely (only do this if you are already running in a container or other isolated env)
codex --sandbox danger-full-access

The same setting can be persisted in ~/.codex/config.toml via the top-level sandbox_mode = "MODE" key, e.g. sandbox_mode = "workspace-write". In workspace-write, Codex also includes ~/.codex/memories in its writable roots so memory maintenance does not require an extra approval.

Code Organization

This folder is the root of a Cargo workspace. It contains quite a bit of experimental code, but here are the key crates:

  • core/ contains the business logic for Codex. Ultimately, we hope this to be a library crate that is generally useful for building other Rust/native applications that use Codex.
  • exec/ "headless" CLI for use in automation.
  • tui/ CLI that launches a fullscreen TUI built with Ratatui.
  • cli/ CLI multitool that provides the aforementioned CLIs via subcommands.

If you want to contribute or inspect behavior in detail, start by reading the module-level README.md files under each crate and run the project workspace from the top-level codex-rs directory so shared config, features, and build scripts stay aligned.