## Why
Removing the selected working directory can prevent filesystem sandbox helpers from launching, even when the requested absolute paths remain accessible. Permission rules must stay anchored to the selected directory while those operations continue.
## What changed
- Require a policy `cwd` in `FileSystemSandboxContext` and launch filesystem helpers from the filesystem root while preserving the policy directory and workspace roots.
- Carry explicit `policyContext` in filesystem RPCs, preserving legacy wire fields and resolving omitted directories from older clients at executor ingress.
- Keep permission paths as executor file URIs and validate host compatibility where they are enforced.
- Bind Windows relative denial globs to the policy directory before changing the helper's launch directory, preserving home-relative patterns.
## Testing
Add regression coverage for `apply_patch` after working-directory removal, legacy RPC directory fallbacks, cross-platform permission URI transport, and Windows relative read denials. The patch regression verifies that an allowed file is updated while an explicitly denied file remains unreadable and unchanged.
GitOrigin-RevId: b0f4db722b27cb72ec129fc297c85732afac11f7
## Why
MXC is a sandbox implementation, not a restricted-token sandbox level. Executor requests need to represent that choice separately from `WindowsSandboxLevel`.
## What changed
- Introduce `WindowsSandboxSelection` for executor sandbox contexts and remove `Mxc` from `WindowsSandboxLevel`.
- Preserve the `windowsSandboxLevel` wire field and its serialized values for compatibility.
- Share sandbox selection between executor process launches and filesystem helpers, and use the new selection in capability discovery and skill reads.
- Disable Windows sandbox selection for executor paths that do not use Windows path conventions.
## Testing
Extend coverage for MXC wire serialization, Windows skill-read sandbox checks, and capability discovery with distinct permissions. Exercise remote filesystem write restrictions with both restricted-token and MXC sandboxes, including rejection when native MXC is unavailable.
GitOrigin-RevId: 266211377bcb138a0dc75861e9ff2225fa37a53d
## What changed
- Run capability discovery for roots with the same sandbox context in one sandbox helper invocation.
- Keep roots with different sandbox permissions isolated, and fall back to per-root discovery if the batched invocation fails.
## Testing
- Add coverage for single-launch batching, fallback after a sandbox launch failure, and roots with different permission profiles.
GitOrigin-RevId: a6e185a8edfd028fc3639b7c6c3cc7da342b6fe3
## Why
Filesystem permission paths can use a convention that differs from the host
running Codex. Converting them immediately to native absolute paths can change
the meaning of ambiguous paths such as `/C:/secret` or Windows UNC paths.
## What changed
- Store literal filesystem permission paths as `PathUri` values through the
runtime policy and execution protocol.
- Keep legacy string-based serialization at explicit protocol boundaries and
reject conversions that cannot be represented losslessly.
- Encode native paths as opaque URIs when a normal file URI would imply the
wrong path convention.
## Testing
Added coverage for cross-platform and ambiguous path round trips, UNC path
variants, permission-profile serialization, and deny-policy enforcement.
GitOrigin-RevId: 5247713796d1f2bb4e02f94eb9fc82d4698060f0
## Why
Executor capability discovery can traverse plugin and skill roots, including
symlinks. Under restricted filesystem permissions, discovery must not expose
files outside the permitted paths.
## What changed
- Pass each environment's filesystem sandbox context through capability root
discovery and apply it to metadata, directory walks, and file reads.
- Enable discovery for restricted sessions so permitted executor skills remain
available while inaccessible roots and symlink targets are omitted.
- Key discovery caches by sandbox context and reject sandboxed discovery on
executors that do not advertise support for it.
- Split requests with more than 128 roots into supported-size batches.
## Testing
- Cover permitted and denied external symlink targets.
- Verify restricted skill listing excludes inaccessible skills.
- Verify cache separation across permission contexts and discovery of 129 roots.
GitOrigin-RevId: 44d16468ca003403bdb8b71a04ae8c9ff94ed494
## Why
Selected capability roots can contribute plugins, MCP servers, connectors, and
skills. Discovering each contribution separately requires repeated access to the
executor filesystem.
## What changed
- Add the `capabilityRoots/discoverV1` exec-server RPC to scan selected roots and
materialize recognized plugin manifests, configuration files, skill
instructions, and skill metadata in one bounded request.
- Add the opt-in `executor_capability_discovery` feature, with a thread-scoped
cache and per-step snapshot shared by MCP and skill discovery.
- Parse MCP, connector, and skill contributions from the materialized snapshot,
including serving cached skill instructions without another filesystem read.
## Testing
- Cover discovery limits, manifest precedence, root-local failures, cache reuse,
plugin contributions, and parity with the existing environment skill loader.
GitOrigin-RevId: f98fd2321cafb58c596db02da1f83c09d8eb375d
