bazel: run sharded rust integration tests (#21057)

## Why

Bazel CI was not actually exercising some sharded Rust integration-test
targets on macOS. The `rules_rust` sharding wrapper expects a symlink
runfiles tree, but this repo runs Bazel with `--noenable_runfiles`. In
that configuration the wrapper could fail to find the generated test
binary, produce an empty test list, and exit successfully. That made
targets such as `//codex-rs/core:core-all-test` look green even when
Cargo CI could still catch failures in the same Rust tests.

The coverage gap appears to have been introduced by
[#18082](https://github.com/openai/codex/pull/18082), which enabled
rules_rust native sharding on `//codex-rs/core:core-all-test` and the
other large Rust test labels. The manifest-runfiles setup itself
predates that change in
[#10098](https://github.com/openai/codex/pull/10098), but #18082 is
where the affected integration tests started running through the
incompatible rules_rust sharding wrapper.
[#18913](https://github.com/openai/codex/pull/18913) fixed the same
class of issue for wrapped unit-test shards, but integration-test shards
were still going through the rules_rust wrapper until this PR.

We still do not have the V8/code-mode pieces stable under the Bazel CI
cross-compile setup, so this keeps those tests out of Bazel while
restoring coverage for the rest of the sharded Rust integration suites.
Cargo CI remains responsible for V8/code-mode coverage for now.

This change did uncover a real failing core test on `main`:
`approved_folder_write_request_permissions_unblocks_later_apply_patch`.
That fix is split into
[#21060](https://github.com/openai/codex/pull/21060), which enables the
`apply_patch` tool in the test, teaches the aggregate core test binary
to dispatch the sandboxed filesystem helper, canonicalizes the macOS
temp patch target, and isolates the core test harness from managed
local/enterprise config. Keeping that fix separate lets this PR stay
focused on restoring Bazel coverage while documenting the first failure
it exposed.

## What changed

- Build sharded Rust integration tests as manual `*-bin` binaries and
run them through the existing manifest-aware `workspace_root_test`
launcher.
- Keep Bazel sharding on the launcher target so Rust test cases are
still distributed by stable test-name hashing.
- Configure Bazel CI to skip Rust tests whose names contain
`suite::code_mode::`.
- Exclude the standalone `codex-rs/code-mode` and `codex-rs/v8-poc`
unit-test targets from `bazel.yml`.

## Verification

- `bazel query --output=build //codex-rs/core:core-all-test` now shows
`workspace_root_test` wrapping `//codex-rs/core:core-all-test-bin`.
- `bazel test --test_output=all --nocache_test_results
--test_sharding_strategy=disabled //codex-rs/core:core-all-test
--test_filter=suite::request_permissions_tool::approved_folder_write_request_permissions_unblocks_later_apply_patch`
runs the actual Rust test body and passes.
- `bazel test --test_output=errors --nocache_test_results
--test_env=CODEX_BAZEL_TEST_SKIP_FILTERS=suite::code_mode::
//codex-rs/core:core-all-test` runs the sharded target with code-mode
skipped and passes overall locally, with one flaky attempt retried by
the existing `flaky = True` setting.

.github/workflows/bazel.yml

@@ -18,9 +18,9 @@ concurrency:
 jobs:
   test:
     # PRs use a fast Windows cross-compiled test leg for pre-merge signal.
-    # Post-merge pushes to main also run the native Windows test job below,
-    # which keeps V8/code-mode coverage without putting PR latency back on the
-    # critical path.
+    # Post-merge pushes to main also run the native Windows test job below for
+    # broader Windows signal without putting PR latency back on the critical
+    # path. Cargo CI owns V8/code-mode test coverage for now.
     timeout-minutes: 30
     strategy:
       fail-fast: false
@@ -46,8 +46,8 @@ jobs:
 
           # Windows fast path: build the windows-gnullvm binaries with Linux
           # RBE, then run the resulting Windows tests on the Windows runner.
-          # The main-only native Windows job below preserves full V8/code-mode
-          # coverage post-merge.
+          # Cargo CI preserves V8/code-mode coverage while Bazel CI keeps broad
+          # non-code-mode signal.
           - os: windows-latest
             target: x86_64-pc-windows-gnullvm
     runs-on: ${{ matrix.os }}
@@ -88,6 +88,11 @@ jobs:
             # path. V8 consumers under `//codex-rs/...` still participate
             # transitively through `//...`.
             -//third_party/v8:all
+            # V8-backed code-mode tests are covered by Cargo CI. Bazel CI
+            # cross-compiles in several legs, and those tests are not stable in
+            # that setup yet.
+            -//codex-rs/code-mode:code-mode-unit-tests
+            -//codex-rs/v8-poc:v8-poc-unit-tests
           )
 
           bazel_wrapper_args=(
@@ -105,15 +110,6 @@ jobs:
               --windows-cross-compile
               --remote-download-toplevel
             )
-            # Tradeoff: the Linux-RBE-built windows-gnullvm V8 archive
-            # currently crashes during direct V8/code-mode smoke tests on the
-            # Windows runner. Keep the broader fast Windows suite in PR CI and
-            # rely on the main-only native Windows job below for full
-            # V8/code-mode signal while we investigate the cross-built archive.
-            bazel_targets+=(
-              -//codex-rs/code-mode:code-mode-unit-tests
-              -//codex-rs/v8-poc:v8-poc-unit-tests
-            )
           fi
 
           ./.github/scripts/run-bazel-ci.sh \
@@ -144,9 +140,8 @@ jobs:
 
   test-windows-native-main:
     # Native Windows Bazel tests are slower and frequently approach the
-    # 30-minute PR budget, but they provide the full V8/code-mode signal that
-    # the fast cross-compiled PR leg intentionally trades away. Run this only
-    # for post-merge commits to main and give it a larger timeout.
+    # 30-minute PR budget. Run this only for post-merge commits to main and give
+    # it a larger timeout.
     if: github.event_name == 'push' && github.ref == 'refs/heads/main'
     timeout-minutes: 40
     runs-on: windows-latest
@@ -174,6 +169,11 @@ jobs:
             # path. V8 consumers under `//codex-rs/...` still participate
             # transitively through `//...`.
             -//third_party/v8:all
+            # Keep this aligned with the main Bazel job. The native Windows
+            # job preserves broad post-merge coverage, but code-mode/V8 tests
+            # are covered by Cargo CI rather than Bazel for now.
+            -//codex-rs/code-mode:code-mode-unit-tests
+            -//codex-rs/v8-poc:v8-poc-unit-tests
           )
 
           bazel_test_args=(