## Why
Agents need a clear default for writing remote-compatible integration
tests and reproducible commands for each supported runner.
## What
Expand the `remote-tests` skill with fixture guidance, skip selection,
and Docker and Wine commands. Add always-visible `AGENTS.md` guidance
that points new core and app-server tests toward automatic environment
fixtures.
Stacked on #29789.
## Why
Core tests should branch on the executor's operating system, not on
runner details such as Docker or Wine. This keeps platform behavior
stable as new test backends are added and reserves Wine-specific skips
for actual runner debt.
## What
- Add `TestTargetOs` and target/host-aware skip helpers while keeping
`TestEnvironment` internal.
- Replace topology enum access with remote predicates and a narrow
Docker accessor.
- Migrate OS-semantic Wine skips, preserve runner-specific gaps, and
document the skip taxonomy.
## Validation
- `just test -p core_test_support`
- `just test -p codex-core
remote_test_env_can_connect_and_use_filesystem`
- `bazel test //codex-rs/core:core-all-wine-exec-test
--test_output=errors` reached test execution; unrelated existing
view-image, path, and timing failures remain.
- `just test -p codex-core` and `just test` reached broad test
execution; this checkout has unrelated helper, sandbox, and timing
failures.
## Why
We want to exercise a linux app-server against a windows exec-server
without having to repeat every test case. This approach has slight
precedent in the remote docker test setup.
## What
Run the shared `codex-core` integration suite against Windows
exec-server behavior from Linux. This makes cross-OS path and shell
regressions visible while keeping unsupported cases owned by individual
tests.
- Add `local`, `docker`, and `wine-exec` test environment selection with
legacy Docker compatibility.
- Extend `codex_rust_crate` to generate a sharded Wine-exec variant
using a cross-built Windows server and pinned Bazel Wine/PowerShell
runtimes.
- Teach remote-aware helpers about Windows paths and track temporary
incompatibilities with source-local `skip_if_wine_exec!` calls and
follow-up reasons.