## Why Recent `main` CI had repeated flakes in the plugin fixture tests: - `codex-core::all suite::plugins::explicit_plugin_mentions_inject_plugin_guidance` failed in runs [24909500958](https://github.com/openai/codex/actions/runs/24909500958), [24908076251](https://github.com/openai/codex/actions/runs/24908076251), [24906197645](https://github.com/openai/codex/actions/runs/24906197645), and [24898949647](https://github.com/openai/codex/actions/runs/24898949647). - `codex-core::all suite::plugins::plugin_mcp_tools_are_listed` failed in runs [24909500958](https://github.com/openai/codex/actions/runs/24909500958), [24908076251](https://github.com/openai/codex/actions/runs/24908076251), and [24898949647](https://github.com/openai/codex/actions/runs/24898949647). The failures were in the same plugin/MCP fixture family: assertions expected sample plugin guidance or tool inventory, but the test could observe the session before the sample MCP server had finished startup. ## Root Cause `explicit_plugin_mentions_inject_plugin_guidance` submitted the user turn immediately after constructing the session. MCP startup is asynchronous, so on a slower or busier CI runner the prompt could be built before the sample plugin MCP server had reported its tools. That made the test depend on scheduler timing rather than the fixture being ready. `plugin_mcp_tools_are_listed` already needed the same readiness condition, but its wait logic was local to that test. ## What Changed - Added a shared `wait_for_sample_mcp_ready` helper for the plugin fixture tests. - Wait for `McpStartupComplete` before submitting the explicit plugin mention turn. - Reuse the same readiness helper in the MCP tool-listing test. ## Why This Should Be Reliable The tests now wait for the explicit readiness signal from the sample MCP server before asserting guidance or tools derived from that server. This removes the startup race while still exercising the real fixture path, so the assertions should only run after the plugin inventory is deterministic. ## Verification - `cargo test -p codex-core --test all plugins::` - GitHub CI for this PR is passing.
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Dependencies
Note that codex-core makes some assumptions about certain helper utilities being available in the environment. Currently, this support matrix is:
macOS
Expects /usr/bin/sandbox-exec to be present.
When using the workspace-write sandbox policy, the Seatbelt profile allows
writes under the configured writable roots while keeping .git (directory or
pointer file), the resolved gitdir: target, and .codex read-only.
Network access and filesystem read/write roots are controlled by
SandboxPolicy. Seatbelt consumes the resolved policy and enforces it.
Seatbelt also keeps the legacy default preferences read access
(user-preference-read) needed for cfprefs-backed macOS behavior.
Linux
Expects the binary containing codex-core to run the equivalent of codex sandbox linux (legacy alias: codex debug landlock) when arg0 is codex-linux-sandbox. See the codex-arg0 crate for details.
Legacy SandboxPolicy / sandbox_mode configs are still supported on Linux.
They can continue to use the legacy Landlock path when the split filesystem
policy is sandbox-equivalent to the legacy model after cwd resolution.
Split filesystem policies that need direct FileSystemSandboxPolicy
enforcement, such as read-only or denied carveouts under a broader writable
root, automatically route through bubblewrap. The legacy Landlock path is used
only when the split filesystem policy round-trips through the legacy
SandboxPolicy model without changing semantics. That includes overlapping
cases like /repo = write, /repo/a = none, /repo/a/b = write, where the
more specific writable child must reopen under a denied parent.
The Linux sandbox helper prefers the first bwrap found on PATH outside the
current working directory whenever it is available. If bwrap is present but
too old to support --argv0, the helper keeps using system bubblewrap and
switches to a no---argv0 compatibility path for the inner re-exec. If
bwrap is missing, it falls back to the vendored bubblewrap path compiled into
the binary and Codex surfaces a startup warning through its normal notification
path instead of printing directly from the sandbox helper. Codex also surfaces
a startup warning when bubblewrap cannot create user namespaces. WSL2 uses the
normal Linux bubblewrap path. WSL1 is not supported for bubblewrap sandboxing
because it cannot create the required user namespaces, so Codex rejects
sandboxed shell commands that would enter the bubblewrap path before invoking
bwrap.
Windows
Legacy SandboxPolicy / sandbox_mode configs are still supported on
Windows. Legacy read-only and workspace-write policies imply full
filesystem read access; exact readable roots are represented by split
filesystem policies instead.
The elevated Windows sandbox also supports:
- legacy
ReadOnlyandWorkspaceWritebehavior - split filesystem policies that need exact readable roots, exact writable roots, or extra read-only carveouts under writable roots
- backend-managed system read roots required for basic execution, such as
C:\Windows,C:\Program Files,C:\Program Files (x86), andC:\ProgramData, when a split filesystem policy requests platform defaults
The unelevated restricted-token backend still supports the legacy full-read
Windows model for legacy ReadOnly and WorkspaceWrite behavior. It also
supports a narrow split-filesystem subset: full-read split policies whose
writable roots still match the legacy WorkspaceWrite root set, but add extra
read-only carveouts under those writable roots.
New [permissions] / split filesystem policies remain supported on Windows
only when they can be enforced directly by the selected Windows backend or
round-trip through the legacy SandboxPolicy model without changing semantics.
Policies that would require direct explicit unreadable carveouts (none) or
reopened writable descendants under read-only carveouts still fail closed
instead of running with weaker enforcement.
All Platforms
Expects the binary containing codex-core to simulate the virtual
apply_patch CLI when arg1 is --codex-run-as-apply-patch. See the
codex-arg0 crate for details.