## Why #29113 moved remote sandbox setup and enforcement to the exec server. That gives the executor ownership of the platform-specific work: a Linux executor chooses and runs a Linux sandbox even when the Codex orchestrator is running on macOS or Windows. It also means the orchestrator no longer knows which concrete sandbox the executor selected. When that sandbox blocks a remote command, the orchestrator currently sees only a failed process and can treat the denial as an ordinary command failure. The existing sandbox approval and retry path is then skipped. This PR lets the executor report one portable fact: > This command probably failed because the executor sandbox blocked it. The executor keeps its concrete sandbox type private. The protocol sends only the semantic result. ## Example Suppose a local macOS Codex session asks a Linux devbox to write outside the allowed workspace. Before this PR: ```text Linux sandbox blocks the write -> remote process exits with "Permission denied" -> local orchestrator sees an ordinary command failure -> the normal sandbox approval and retry path can be skipped ``` With this PR: ```text Linux sandbox blocks the write -> executor reports sandboxDenied: true -> unified exec returns UnifiedExecError::SandboxDenied -> the existing approval prompt is shown -> an approved retry runs through the existing unsandboxed retry path ``` ## What changes ### The executor remembers its selected sandbox The prepared remote process now retains the executor-selected `SandboxType`. This value never crosses the executor boundary. Commands started without a sandbox retain `SandboxType::None` and are never reported as sandbox denials. ### The executor uses the existing denial heuristic The existing local denial heuristic moves from `codex-core` into the shared `codex-sandboxing` crate. When a sandboxed remote process exits, the executor: 1. waits the same short output grace period used by local unified exec; 2. reads the output currently available in the existing retained output buffer; 3. runs the existing heuristic using the exit code and common denial messages; 4. stores the yes/no result before publishing the process exit. This deliberately matches the old local unified-exec behavior. It does not add a new streaming classifier, another output buffer, or stronger output-retention guarantees. ### The protocol reports a portable boolean `process/read` gains `sandboxDenied`: ```json { "exited": true, "exitCode": 1, "closed": false, "sandboxDenied": true } ``` The field defaults to `false` when an older executor omits it. The response does not expose the executor sandbox implementation or executor-native paths. ### Unified exec uses the existing error path The exec-server client carries `sandboxDenied` into the unified process state. If it is true, unified exec returns the existing `SandboxDenied` error instead of trying to classify remote output using an orchestrator-side sandbox type. Remote process exit remains visible as soon as the process exits. This PR does not wait for stdout or stderr to close and does not change the existing process lifecycle. ## Scope This PR is intentionally limited to matching the existing local unified-exec behavior for the initial command execution path. It does not add: - incremental denial tracking across the full output stream; - new denial handling for commands completed later through `write_stdin`; - new guarantees for preserving the semantic flag during the narrow reconnect-recovery race. Those can be considered separately if the same behavior is added for local execution. ## Test coverage One remote end-to-end integration test covers the complete intended flow: ```text remote read-only sandbox -> denied write -> executor reports the denial -> Codex requests approval -> user approves -> retry succeeds on the remote executor ``` Existing lifecycle coverage continues to verify that remote process exit is reported before late output streams close.
codex-core
This crate implements the business logic for Codex. It is designed to be used by the various Codex UIs written in Rust.
Wine-exec integration tests
On x86-64 Linux, run the shared suite against the Windows exec server with
bazel test //codex-rs/core:core-all-wine-exec-test. Temporary blockers use a
source-local skip_if_wine_exec! call and reason.
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
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.