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codex/codex-rs/core
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jif c3a479620f Add selected-plugin precedence and attribution to the MCP catalog (#27884)
## Why

**In short:** this PR resolves already-discovered MCP registrations. It
does not read selected plugins or discover their MCP servers.

The resolved MCP catalog currently builds config and auto-discovered
plugin registrations before runtime contributors are applied. A
thread-selected plugin needs a distinct precedence tier in that same
initial resolution pass: otherwise a disabled lower-precedence winner
can leave stale name-level state behind, and the winning MCP tools
cannot be attributed to the selected package reliably.

This PR adds that catalog boundary before executor discovery is
connected.

## What changed

- Added an explicit selected-plugin registration tier between
auto-discovered plugins and explicit config.
- Collected selected-plugin contributions before the initial catalog
build, while leaving compatibility and generic extension overlays in
their existing runtime phase.
- Retained the winning plugin ID and display name directly on
plugin-owned catalog registrations.
- Derived MCP tool provenance from the winning catalog entry instead of
joining against local-only plugin summaries.
- Retained the winning selected server's tool approval policy in the
running connection manager, so a selected registration cannot inherit
approval behavior from a losing local plugin.
- Kept remembered approval session-scoped for selected plugins until
there is an authority-aware persistence contract; Codex will not write
approval back to an unrelated local plugin.
- Preserved existing name-level disabled vetoes for discovered plugins
and config, while keeping a selected package's own disabled registration
scoped to that registration.
- Preserved deterministic selection order and existing config,
compatibility, and extension precedence.

The resulting order is:

```text
auto-discovered plugin
  < selected plugin
  < explicit config
  < compatibility registration
  < extension overlay
```

## Behavior and scope

This is a catalog and provenance change only. No production host
contributes selected-plugin MCP registrations yet, so existing local MCP
behavior remains unchanged.

The stacked follow-up, #27870, installs the executor plugin provider
that produces these registrations. App-server activation remains a
separate final step.

## Verification

Focused tests cover precedence, deterministic selected-plugin conflicts,
disabled-veto behavior across catalog phases, managed requirements
before selected-plugin resolution, winning-server approval policy, and
attribution when local and selected packages share an ID or server name.
CI owns execution of the test suite.
c3a479620f ยท 2026-06-15 11:10:51 +02:00
History
..

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 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 bundled codex-resources/bwrap binary shipped with Codex 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 ReadOnly and WorkspaceWrite behavior
  • 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), and C:\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.