## Why
Subagents inherit applied instruction snapshots, so later provider updates do not reach running descendants. Hosts need an explicit way to share current thread instructions across an agent tree.
## What changed
- Add `ThreadInstructionsProvider::share_with_subagents()`, defaulting to `false`. Opted-in descendants refresh instructions at their next model-request boundary.
- Retain shared providers across root unloads and descendant reloads. Let a resumed root replace the provider for surviving descendants, or preserve their last shared instructions when it supplies a non-sharing provider.
- Keep providers scoped to their root tree and preserve snapshot-only instructions for root forks and isolated sessions, including Guardian reviews.
## Testing
Add coverage for child and grandchild instruction updates and clearing, provider replacement after root restart, lazy descendant reloads, default snapshot inheritance, and isolation between roots and Guardian sessions.
GitOrigin-RevId: 44c9fb7fe9ae1f96156bdf3c47ab6c4a81bd65e9
## What changed
- Expose `ThreadInstructionsProvider` through `StartThreadOptions`. Load its snapshot at startup and model-request boundaries, composing it after global instructions and before repository instructions. Empty or blank output clears only the thread contribution.
- Reject thread instructions exceeding 10,000 estimated tokens independently of the repository instruction budget. Allow host-provided instructions without a filesystem source and rename the shared future type to `LoadInstructionsFuture`.
- Retain the provider across warm resumes; require hosts to supply it again for cold resumes and offline forks. Live forks and subagents inherit applied snapshots without inheriting the source thread's provider, including when the parent is unloaded during setup or reload.
- Include thread instructions in guardian reviewer inheritance and reuse decisions.
## Testing
Add coverage for composition and clearing, refresh within an active turn, size rejection before sampling, cancellation-safe refresh, fork and resume behavior, parent eviction, and reviewer reuse invalidation.
GitOrigin-RevId: 7be9a523cbbfd67704067dfd526188dad89a3c88
## Why
Running root threads retained their startup global instructions, so edits to global `AGENTS.md` files did not take effect during an active session.
## What changed
- Reload global instructions when capturing model-request context, including after tools within the same turn. Apply changes without repeating unchanged instructions or rediscovering repository instructions when the environment and trust level are unchanged.
- Preserve the last successful global instructions on read failures, suppress recurring warnings until recovery, and clear instructions when their source is removed or blank.
- Serialize refreshes and allow cancellation without blocking subsequent requests.
- Give new subagents the parent's applied instruction snapshot and update Guardian reviewer reuse to account for refreshed instructions.
## Testing
Add regression coverage for live edits and removal, read failures and recovery, warning suppression, cancellation, subagent inheritance, and Guardian reviewer reuse. Update resume, fork, and compaction tests to verify refreshed instructions.
GitOrigin-RevId: f7e9b399740fa4f45e482c070f6e901ee7cf85cd
## What changed
Rename the `UserInstructions` type to `Instructions` across the extension API,
its core API re-export, and all consumers. This keeps loading behavior and the
`LoadedUserInstructions` provider interface unchanged.
GitOrigin-RevId: 1ac236b34c31718e7aa38ff5eae5e9b179aeedd8
## 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`
vinh-gpt