## Why
With deferred executors, a turn can begin before a remote environment
attaches. AGENTS.md discovery previously ran only during session setup,
so instructions from a later environment never reached the model or the
session instruction sources.
WorldState persistence has now landed, so this uses the durable
model-visible baseline directly instead of carrying a temporary
resume/fork compatibility path.
## What
- Add an `AgentsMdManager` in `SessionServices` to own host
instructions, loaded state, and refresh caching.
- When `DeferredExecutor` is enabled, refresh AGENTS.md when attached
environment selections change and freeze the result in the corresponding
`StepContext`.
- Represent AGENTS.md as a persisted WorldState section for every
session, with bounded initial, replacement, and removal updates.
- Remove duplicate AGENTS.md state and rendering from
`SessionConfiguration` and `TurnContext`.
- Build initial context, per-request updates, and compaction context
from the same step-scoped value.
- On resume and fork, compare current instructions with the restored
WorldState baseline and inject a replacement exactly once when they
differ.
Builds on #29833, #29835, and #29837.
## Tests
- Covers a remote environment becoming ready mid-turn, with AGENTS.md
appearing on the next request exactly once and updating canonical
instruction sources.
- Covers full, unchanged, replaced, and removed AGENTS.md WorldState
rendering.
- Covers changed instructions across cold resume and fork without
duplicate reinjection.
- Covers remote-v2 compaction retaining creation-time instructions in
the live session and cold resume appending one replacement when the
source changed.
- Ran focused `codex-core` AGENTS.md, WorldState, and context-update
test suites.
## Why
When Codex uses a remote `ExecutorFileSystem`, every `get_metadata` call
is an exec-server round trip. Upward discovery currently pays those
round trips serially in two latency-sensitive places:
- session startup, while locating the configured project root before
loading `AGENTS.md`; and
- Git-root discovery, which runs before per-turn Git diff enrichment.
The goal is to remove the serial ancestor dependency without adding a
new filesystem RPC, JSON-RPC batch method, Git executable dependency, or
cache.
## Example
Assume this layout, with `.git` as the configured project-root marker:
```text
/workspace/repo/.git
/workspace/repo/AGENTS.md
/workspace/repo/crates/core/ <- cwd
```
The marker probes have this required precedence:
```text
1. /workspace/repo/crates/core/.git
2. /workspace/repo/crates/.git
3. /workspace/repo/.git
4. /workspace/.git
5. /.git
```
Previously, probe 2 was not sent until probe 1 returned, and probe 3 was
not sent until probe 2 returned. With this change, the client lazily
keeps up to eight ordinary `fs/getMetadata` requests in flight, but
consumes their results in the order above. Codex must still learn that
probes 1 and 2 are absent before accepting probe 3, so the nearest root
always wins. Once probe 3 succeeds, the client has its answer and stops
awaiting probes 4 and 5. Requests that were already sent may still
finish on the worker.
For the marker phase alone, with a 50 ms client-to-worker round trip and
fast local metadata calls, finding the root at probe 3 changes from
roughly three serialized round trips (150 ms) to one round trip plus
worker processing. The later `AGENTS.md` candidate phase remains
separate and ordered.
Only after `/workspace/repo` is selected does `AGENTS.md` discovery
check instruction candidates, in root-to-cwd order:
```text
/workspace/repo/AGENTS.override.md
/workspace/repo/AGENTS.md
/workspace/repo/crates/AGENTS.override.md
/workspace/repo/crates/AGENTS.md
/workspace/repo/crates/core/AGENTS.override.md
/workspace/repo/crates/core/AGENTS.md
```
The first configured candidate found in each directory wins. These
checks remain ordered and no instruction candidate above
`/workspace/repo` is issued. Git-root discovery uses the same bounded
lookup with only `.git` as the marker.
## What changed
- Added a client-side find-up helper that generates `ancestor x marker`
probes lazily, nearest directory first and configured marker order
within each directory.
- Uses an ordered concurrency window of eight scalar metadata requests.
This bounds executor load while preserving nearest-root and marker
precedence.
- Reuses the helper for both configured project-root discovery and
remote Git-root discovery.
- Keeps Git ancestor and marker construction in `AbsolutePathBuf`,
converting only each complete `.git` probe to `PathUri`. This preserves
native paths that require an opaque URI fallback, such as Windows
namespace paths.
- Preserves existing error behavior: `AGENTS.md` discovery propagates
non-`NotFound` metadata errors, while Git discovery treats a failed
marker probe as absent and continues upward.
- Reads each discovered `AGENTS.md` directly instead of statting it a
second time.
No filesystem trait or exec-server protocol method is added. An empty
`project_root_markers` list performs no ancestor-marker I/O and checks
instruction candidates only in `cwd`. This change also deliberately does
not cache roots across turns.
## Symlinks
Upward traversal remains **lexical**. The helper does not canonicalize
`cwd`; it appends marker names to the supplied path and walks that
path's textual parents. The filesystem performs the actual metadata/read
operation, and the current local and exec-server implementations follow
live symlink targets.
For example:
```text
/tmp/pkg -> /workspace/repo/packages/pkg
cwd = /tmp/pkg/src
actual Git marker = /workspace/repo/.git
```
The lexical probes are `/tmp/pkg/src/.git`, `/tmp/pkg/.git`,
`/tmp/.git`, and `/.git`. They do not jump from `/tmp/pkg` to the
target's parent `/workspace/repo`, so this spelling of `cwd` does not
discover `/workspace/repo/.git`. That is the existing behavior and is
unchanged by this PR.
Conversely, if `/tmp/repo -> /workspace/repo`, then probing
`/tmp/repo/.git` follows the directory symlink and finds
`/workspace/repo/.git`; the reported root remains the lexical path
`/tmp/repo`. A live symlink used directly as `.git`, another configured
marker, or `AGENTS.md` is also followed. A symlinked `AGENTS.md` is
loaded when its target is a regular file, while a broken symlink behaves
as `NotFound`.
## Why
Config layer provenance describes how effective configuration was
assembled, so it belongs with the config loader rather than in
app-server's serialized API types.
## What changed
- Moved `ConfigLayerSource`, `ConfigLayerMetadata`, and `ConfigLayer`
ownership into `codex-config`.
- Kept app-server's wire payloads unchanged and added explicit
conversions at the app boundary.
- Removed lower-level app-server-protocol dependencies from config
consumers.
## Stack
This is PR 3 of 6, stacked on [PR
#29721](https://github.com/openai/codex/pull/29721). Review only the
delta from `codex/split-auth-domain-types`. Next: [PR
#29723](https://github.com/openai/codex/pull/29723).
## Validation
- `codex-config` coverage passed.
- App-server config-manager and config RPC coverage passed.
## Why
No need to do path contortions when it's for our own logs.
## What
Follow up on a previous PR's nit and update the path-types skill for
future reference.
## Why
`child_agents_md` is a disabled, under-development experiment that adds
a second model-visible explanation of hierarchical `AGENTS.md` behavior.
Keeping it leaves unused prompt, configuration, documentation, and test
surface.
## What changed
- remove the `ChildAgentsMd` feature and `child_agents_md` config schema
entry
- remove the hierarchical prompt asset, export, and instruction
injection
- remove feature-specific tests and documentation
- keep the generic unstable-feature warning coverage using
`apply_patch_streaming_events`
Normal project `AGENTS.md` discovery and composition are unchanged.
## Testing
- `just test -p codex-features`
- `just test -p codex-prompts`
- `just test -p codex-core agents_md`
- `just test -p codex-core unstable_features_warning`
## Why
Make it possible to load AGENTS.md from remote exec-servers whose OS is
different than app-server.
## What
- keep `AGENTS.md` discovery and provenance as `PathUri`, with
root-aware parent and ancestor traversal
- expose lifecycle instruction sources as legacy app-server path strings
in events while retaining `PathUri` internally
- preserve and test mixed POSIX and Windows paths in model context and
TUI status output
- cover remote Windows loading end to end by seeding the Wine prefix
through host filesystem APIs
- fix bug in `PathUri`'s parent() implementation that would erase
Windows drive letters
## Why
app-server may run on a different OS from the selected exec-server
environment. Parsing that environment’s cwd with the Codex host’s path
rules prevents thread startup.
## What
Carry environment cwd values as `LegacyAppPathString` at the app-server
boundary and `PathUri` internally. Existing tool-call schemas and
relative-path behavior stay host-native; remaining local-only consumers
convert explicitly and leave follow-up TODOs.
The Wine integration test verifies app-server can start a thread and
complete an ordinary turn with a Windows environment cwd from Linux.
## Validation
- `bazel test //codex-rs/core/tests/remote_env_windows:smoke-test
--test_output=errors`
- focused app-server environment-selection and protocol schema tests
- scoped Clippy for `codex-core` and `codex-app-server-protocol`
## Why
Shell snapshots are currently session-scoped even though shell and cwd
are properties of a selected turn environment. That makes snapshot
refresh depend on separate session-cwd plumbing, prevents retained
environments from retaining their snapshot work, and can make snapshot
construction use a different shell than command execution.
This follows #27955 by making the retained thread-environment service
own environment snapshot lifecycles. Session configuration remains the
requested selection state, while `ThreadEnvironments` remains the source
of successfully resolved environments.
## What changed
- Configure the shell-snapshot builder before initial environment
resolution.
- Start each local environment snapshot task when its `TurnEnvironment`
is built and retain that shared task while environment ID and cwd still
match.
- Inherit retained environment snapshots into spawned child threads.
- Carry the selected `TurnEnvironment` through shell runtimes so
snapshot construction and command execution use the same
environment-specific shell and cwd.
- Load project instructions and warm plugins/skills after initial
environment resolution.
- Continue decoding invalid UTF-8 instruction files lossily without
emitting a startup warning.
- Keep requested selections in `SessionConfiguration`; failed or
duplicate resolutions only affect the resolved environment snapshot.
## Validation
- `cargo check -p codex-core --tests`
- `just test -p codex-home instructions` (6 passed)
- Focused environment, instruction, shell-snapshot, and user-shell tests
(84 passed)
- Focused shell-snapshot, user-shell, and unified-exec tests (126
passed; two event-timing tests passed on retry)
## Why
Selected execution environments are thread-scoped resources, but startup
and turn construction repeatedly resolved their IDs and working
directories. That discarded existing environment handles and shell
metadata even when a selection had not changed.
Session configuration updates also need to affect future turns without
changing the resolved environment set already captured by a running
turn.
## What changed
- Create a `ThreadEnvironments` service inside `Codex` from the spawned
`EnvironmentManager` and raw environment selections, then store it on
`SessionServices`.
- Split service construction from `update_selections`, allowing session
configuration updates to mutate the resolved set in place.
- Retain an existing `TurnEnvironment` when its environment ID and
working directory match; resolve only added or changed selections and
remove selections that are no longer present.
- Normalize duplicate IDs by keeping the first selection and skip
individual selections that fail to resolve instead of rejecting the
entire update.
- Give each `TurnContext` a cloned `TurnEnvironmentSnapshot`, so later
session configuration updates affect future turns without rewriting an
active turn.
- Reuse the service-owned environment manager and resolved snapshot for
startup work, MCP initialization, and child-thread spawning instead of
flowing resolved environments through spawn arguments.
## Test plan
- `cargo check -p codex-core --tests`
- `just test -p codex-core environment_selection`
- `just test -p codex-core turn_environments`
- `just test -p codex-core
session_update_settings_does_not_rewrite_sticky_environment_cwds`
- `just test -p codex-core
default_turn_does_not_overlay_legacy_fallback_cwd_onto_stored_thread_environments`
## Why
`PathUri::from_abs_path` can fail for absolute paths that do not have a
normal `file:` URI representation, forcing filesystem call sites to
handle a conversion error even though the original path can be preserved
losslessly.
## What
Make `from_abs_path` infallible and migrate its callers. Unrepresentable
paths use `file:///%00/bad/path/<base64>`, encoding Unix bytes or
Windows UTF-16LE; `to_abs_path` validates and decodes that fallback. The
leading encoded null reserves a namespace that cannot collide with a
real Unix or Windows path, and fallback URIs remain opaque to lexical
path operations.
## Validation
Added path-URI coverage for Unix null and non-UTF-8 paths, Windows
device/verbatim and non-Unicode paths, serialization, malformed
fallbacks, opaque lexical operations, invalid native payloads, and
literal `/bad/path` collision resistance.
## Why
Sandbox cwd values can cross app-server and exec-server host boundaries.
They should retain URI semantics until the receiving host validates them
instead of being interpreted early as native paths.
## What
- Carry `PathUri` through filesystem sandbox contexts, sandbox commands,
and transform inputs.
- Convert command and policy cwd once in `SandboxManager::transform`,
then keep launch requests native.
- Preserve sandbox cwd over remote filesystem transport and reject
non-native URIs without fallback.
- Cache paired native/URI turn-environment cwd values during migration,
with immutable access to keep them synchronized.
- Extend existing protocol, forwarding, transform, and core runtime
tests.
## Why
We already have the machinery to support multiple environments on a
single thread, but we only show the model the contents of `AGENTS.md`
files in the primary environment.
We should show the model all of the relevant project instructions when
we know there's more than one environment.
## Known Gaps
As discussed in the RFC, this implementation:
1. doesn't handle environments being added/removed to/from the thread
after its creation
2. it doesn't enforce an aggregate context budget across environments,
and instead applies the configured project maximum independently to each
environment
## Implementation
- Discover project instructions in environment order with an independent
byte budget per environment and preserve source provenance/order.
- Keep the legacy fragment byte-for-byte when exactly one environment
contributes project instructions; use environment-labeled sections when
two or more environments contribute.
- Freeze the complete rendered fragment in `LoadedAgentsMd`, insert it
directly into requests, and recognize both layouts in contextual and
memory filtering.
- Add exact rendering, independent-budget, source-order,
creation-snapshot, and consumer coverage without changing app-server
schemas.
## Why
We want to remove implicit use of `$CODEX_HOME` from `codex-core` and
make embedders responsible for supplying user-level instructions. This
also ensures user instructions load when no primary environment is
selected.
## What changed
Stacked on #27415, which makes `codex exec` surface thread-scoped
runtime warnings.
- Added `UserInstructionsProvider` to `codex-extension-api`, with
absolute source attribution and recoverable loading warnings.
- Added `codex-home` with the filesystem-backed provider for
`AGENTS.override.md` and `AGENTS.md`, preserving precedence, fallback,
trimming, lossy UTF-8 handling, and the existing uncapped global
instruction size.
- Removed global instruction loading from `Config` and require
`ThreadManager` callers to inject a provider.
- Load provider instructions once for each fresh root runtime, including
runtimes without a primary environment. Running sessions retain their
snapshot, while child agents inherit the parent snapshot without
invoking the provider.
- Keep provider instructions separate while loading project `AGENTS.md`,
then assemble the model-visible instructions with the existing ordering,
source attribution, warning, and turn-context behavior.
- Wired the Codex home provider through the CLI, app server, MCP server,
core facade, and thread-manager sample.
## Validation
- `just test -p codex-home -p codex-extension-api`
- `just test -p codex-core agents_md`
- `just test -p codex-core guardian`
- `just test -p codex-app-server
thread_start_without_selected_environment_includes_only_global_instruction_source`
- `just test -p codex-exec warning`
- `just bazel-lock-check`
## Why
We're moving exec-server to use PathUri for its internal path
representations.
## What
Move `ExecutorFileSystem` APIs to use `PathUri` instead of
`AbsolutePathBuf`. Future changes will convert higher-level parts of
exec-server.
## Intent
Follow up on #26205 by avoiding unnecessary filesystem canonicalization
during `AGENTS.md` discovery. The configured working directory is
already absolute, and canonicalization incorrectly switches symlinked
workspaces from their logical parent hierarchy to the target's
hierarchy.
## User-facing behavior
For a symlinked working directory such as:
```text
test-root/
|-- logical-repo/
| |-- AGENTS.md ("logical parent doc")
| `-- workspace ------------> physical-repo/workspace/
`-- physical-repo/
|-- AGENTS.md ("physical parent doc")
`-- workspace/
`-- AGENTS.md ("workspace doc")
```
Before this change, Codex canonicalized `logical-repo/workspace` to
`physical-repo/workspace` before discovery. It therefore loaded
`physical-repo/AGENTS.md` and `physical-repo/workspace/AGENTS.md`,
ignoring the instructions from the repository through which the user
entered the workspace.
After this change, ancestor discovery walks the configured logical path,
so Codex loads `logical-repo/AGENTS.md`. Opening
`logical-repo/workspace/AGENTS.md` still follows the symlink through the
host filesystem, so the workspace document is also loaded.
`physical-repo/AGENTS.md` is not loaded.
## Implementation
Use the logical absolute working directory when discovering project
instructions and reporting instruction sources. Filesystem reads still
follow the working-directory symlink, so an `AGENTS.md` in the target
workspace continues to load while ancestor discovery uses the symlink's
parents.
## Validation
Added integration coverage proving that discovery loads the logical
parent's instructions and the target workspace's instructions, but not
the target parent's instructions.
## Why
Workspace-specific `AGENTS.md` loading needs to use the selected
environment filesystem so remote workspaces and child agents read
instructions from their actual environment instead of the host
filesystem. The app-server should report the same instruction sources
the initialized thread actually loaded, rather than independently
rescanning configuration and filesystem state.
## What changed
- Introduce `LoadedAgentsMd` to retain ordered user, project, and
internal instructions with their provenance.
- Load and canonicalize workspace `AGENTS.md` paths through the primary
`EnvironmentManager` environment, then render the loaded instructions
when constructing turn context.
- Expose cached loaded instruction sources from initialized threads and
use them for app-server start, resume, and fork responses.
- Preserve global `CODEX_HOME` loading and separator behavior while
excluding empty project files that did not supply model-visible
instructions.
- Add integration coverage for CLI injection, selected-environment
provenance and rendering, empty environment selection, and cached
sources on loaded-thread resume.
## Validation
- `just test -p codex-core agents_md`
- `just test -p codex-core
selected_environment_sources_match_model_visible_instructions`
- `just test -p codex-exec agents_md`
- `just test -p codex-app-server instruction_sources`
- `just test -p codex-app-server --status-level fail`
## Why
`codex_core` is consistently a bottleneck for incremental builds during
iteration. The simplest fix is to make the crate smaller.
## Summary
`codex-core` owns several reusable prompt renderers and static prompt
assets, which makes the crate harder to split apart.
Rename `codex-review-prompts` to `codex-prompts` and move shared review,
goal, permissions, compaction, realtime, hierarchical AGENTS.md, and
`apply_patch` prompts into it. Move prompt-only tests and update
consumers and `CODEOWNERS`.
## Validation
- `just test -p codex-prompts -p codex-apply-patch`
- `just test -p codex-core prompt_caching`
- Bazel builds for the affected crates
Fixes#23223.
## Why
Malformed AGENTS instructions should not fail silently. The reported
issue had invalid UTF-8 in a global `AGENTS.md`; before this change,
Codex treated that decode failure like a missing file, so the personal
instructions disappeared without a user-visible explanation and the
rollout had no `# AGENTS.md instructions` block.
Project-level AGENTS files already used lossy decoding, so their
instructions still appeared, but invalid bytes were replaced without
telling the user. Global and project AGENTS files should behave
consistently: keep usable instruction text when possible, and surface a
diagnostic when bytes had to be replaced.
## What changed
Global `AGENTS.override.md` and `AGENTS.md` loading now reads bytes and
decodes with replacement characters on invalid UTF-8, matching
project-level AGENTS behavior. Both global and project AGENTS loading
now emit a startup warning when invalid UTF-8 is found, and both keep
the instruction text with invalid byte sequences replaced.
Missing files, non-file candidates, empty files, and the existing
`AGENTS.override.md` before `AGENTS.md` precedence keep their current
behavior.
## How users see it
The warnings flow through the existing startup warning surface.
App-server clients receive config-time startup warnings as
`configWarning` notifications during initialization, and thread startup
emits startup warnings as thread-scoped `warning` notifications.
Global AGENTS invalid UTF-8 warnings can appear on both surfaces.
Project-level AGENTS invalid UTF-8 warnings are discovered while
building thread instructions, so they appear as thread-scoped `warning`
notifications. Clients that render warning notifications in the
conversation surface show the message as a visible diagnostic instead of
silently hiding or altering instructions.
## Summary
- make `load_global_instructions` read through an `ExecutorFileSystem`
- call global AGENTS reads with explicit `LOCAL_FS` so they stay tied to
local codex-home state
## Validation
- `bazel test --bes_backend= --bes_results_url=
--test_filter=instruction_sources_include_global_before_agents_md_docs
//codex-rs/core:core-unit-tests` on `dev`
## Why
Config loading had become split across crates: `codex-config` owned the
config types and merge logic, while `codex-core` still owned the loader
that assembled the layer stack. This change consolidates that
responsibility in `codex-config`, so the crate that defines config
behavior also owns how configs are discovered and loaded.
To make that move possible without reintroducing the old dependency
cycle, the shell-environment policy types and helpers that
`codex-exec-server` needs now live in `codex-protocol` instead of
flowing through `codex-config`.
This also makes the migrated loader tests more deterministic on machines
that already have managed or system Codex config installed by letting
tests override the system config and requirements paths instead of
reading the host's `/etc/codex`.
## What Changed
- moved the config loader implementation from `codex-core` into
`codex-config::loader` and deleted the old `core::config_loader` module
instead of leaving a compatibility shim
- moved shell-environment policy types and helpers into
`codex-protocol`, then updated `codex-exec-server` and other downstream
crates to import them from their new home
- updated downstream callers to use loader/config APIs from
`codex-config`
- added test-only loader overrides for system config and requirements
paths so loader-focused tests do not depend on host-managed config state
- cleaned up now-unused dependency entries and platform-specific cfgs
that were surfaced by post-push CI
## Testing
- `cargo test -p codex-config`
- `cargo test -p codex-core config_loader_tests::`
- `cargo test -p codex-protocol -p codex-exec-server -p
codex-cloud-requirements -p codex-rmcp-client --lib`
- `cargo test --lib -p codex-app-server-client -p codex-exec`
- `cargo test --no-run --lib -p codex-app-server`
- `cargo test -p codex-linux-sandbox --lib`
- `cargo shear`
- `just bazel-lock-check`
## Notes
- I did not chase unrelated full-suite failures outside the migrated
loader surface.
- `cargo test -p codex-core --lib` still hits unrelated proxy-sensitive
failures on this machine, and Windows CI still shows unrelated
long-running/timeouting test noise outside the loader migration itself.
## Summary
`codex.emitImage` accepted arbitrary image MIME types for byte payloads
and data URLs. That allowed a value like `image/rgba` to be wrapped as
an `input_image`, even though it is not a supported encoded image
format, so the invalid image could reach the model-input path and
trigger output sanitization.
This results in a panic in debug builds because the output sanitization
is meant as a final safety net, not a primary means of rejecting invalid
image types. I've hit this case multiple times when executing certain
long-running tasks.
This PR rejects unsupported image MIME types before they are emitted
from `js_repl`.
## Changes
- Validate `codex.emitImage({ bytes, mimeType })` in the JS kernel so
only encoded PNG, JPEG, WebP, or GIF payloads are accepted.
- Apply the same MIME allowlist to direct image data URLs, including the
Rust host-side validation path.
- Clarify the JS REPL instructions so agents know byte payloads must
already be encoded as PNG/JPEG/WebP/GIF.
sayan-oai ·
jif ·
Adam Perry @ OpenAI ·
pakrym-oai ·
Eric Traut ·
starr-openai ·
Curtis 'Fjord' Hawthorne ·