## Why
Filesystem helpers intentionally run with a minimal environment that
excludes proxy variables. After filesystem operations started using the
Windows sandbox wrapper, the wrapper derived an empty proxy
configuration from that helper environment and compared it with the
persistent sandbox setup marker. When the marker contained proxy ports,
every filesystem operation appeared to require a firewall update, which
could launch elevated setup, show a UAC or loader dialog, and fail
operations such as `apply_patch` with error 1223.
Filesystem helpers do not use network access, so they should preserve
the proxy/firewall state established by normal sandboxed process
launches.
## What changed
- Add an explicit Windows sandbox proxy-settings mode for reconciling or
preserving persistent proxy state.
- Use preserve mode for filesystem helpers while normal process launches
continue to reconcile proxy settings from their environment.
- Carry the selected proxy state consistently through setup validation,
elevated setup, and non-elevated ACL refreshes.
- Cover wrapper argument propagation and marker-derived proxy
preservation.
## Validation
- `cargo build -p codex-cli --bin codex`
- `just test -p codex-windows-sandbox
preserving_proxy_settings_uses_the_existing_marker`
- `just test -p codex-windows-sandbox windows_wrapper_args_round_trip`
- `just test -p codex-windows-sandbox
setup_request_prefers_explicit_proxy_settings`
- `just test -p codex-sandboxing transform_for_direct_spawn_windows`
- `just test -p codex-exec-server fs_sandbox::tests`
- Ran the same sandboxed `fs/writeFile` reproduction against published
`0.142.0-alpha.6` and the new CLI. The published CLI launched elevated
setup and failed with `ShellExecuteExW ... 1223`; the new CLI completed
without elevation.
Related to #28359.
## Why
Managed network configures commands to use local HTTP and SOCKS proxies.
For commands delegated to the exec server, the proxy environment and the
sandbox policy were prepared separately. On macOS, that meant a command
could receive `HTTPS_PROXY=http://127.0.0.1:43123` while Seatbelt still
denied access to port `43123`.
## What changed
`NetworkProxy` now prepares the command environment and sandbox context
together from the same runtime snapshot:
```text
Prepared managed network
├── command environment: HTTPS_PROXY=http://127.0.0.1:43123
└── sandbox context: allow outbound to 127.0.0.1:43123
```
That context travels with remote exec requests. The exec server
preserves the managed proxy and CA environment, and macOS Seatbelt
allows only the prepared loopback proxy ports without enabling broad
network access or local binding.
The protocol field is optional and the existing enforcement flag remains
in place, preserving compatibility with callers that do not send the new
context.
## 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.
## Why
PR #29108 lets the orchestrator send sandbox intent with `process/start`
without wrapping the command for its own operating system.
This PR completes that boundary by making the executor interpret and
enforce the intent using its own filesystem paths and sandbox
implementation.
For example, a macOS TUI targeting a Linux devbox sends `/bin/bash -lc
pwd`. The Linux executor turns that into its own `codex-linux-sandbox
... /bin/bash -lc pwd` launch.
## What changes
- Keep `process/start` unchanged when no sandbox intent is present.
- Convert sandbox `PathUri` values into native paths on the executor.
- Bind symbolic `:workspace_roots` permissions to the executor's native
sandbox cwd.
- Select the sandbox implementation on the executor and wrap the
original command immediately before spawning it.
- Reject sandbox-required execution before spawning when the executor
cannot enforce the intent.
- Pass exec-server runtime paths into process creation so Linux can
locate `codex-linux-sandbox`.
The boundary is therefore:
```text
orchestrator executor
original argv + sandbox intent -> select and enforce local sandbox
```
This PR intentionally treats a denied remote command as an ordinary
command failure. Draft follow-up #29424 carries a semantic
`sandboxDenied` result back to unified exec for the existing approval
and retry flow.
## Platform scope
Linux and macOS use their existing direct-spawn sandbox transforms.
Windows sandboxed remote process launch is intentionally unsupported in
this PR. The current Windows direct-spawn wrapper does not correctly
preserve arbitrary argv, TTY behavior, or pass the full child
environment out of band. The executor rejects the request instead of
running it incorrectly or unsandboxed.
## Known follow-ups
- The transported permission profile can still contain
orchestrator-materialized helper or explicit paths. A `TODO(jif)` marks
where the executor boundary should receive pre-host-materialization
permission intent.
- The sandbox wrapper currently replaces a requested custom inner
`arg0`. A `TODO(jif)` marks where this must be preserved or rejected
explicitly.
- Draft PR #29424 contains the deferred sandbox-denial classification
and approval/retry behavior.
## Rollout assumption
This executor-sandbox stack is unreleased and its client and executor
are expected to move together. This PR does not add mixed-version
negotiation with older exec servers.
