fix(gateway): preserve context during manual compression

[dyreckt]

What does this PR do?

Preserves the caller's contextvars when the gateway /compress command moves _compress_context() to a worker thread.

The manual compression path used loop.run_in_executor() with a plain lambda. Executor workers do not inherit the caller context, so multiplexed gateway state such as the profile-specific secret scope disappeared in the worker. Auxiliary compression could then report a configured provider credential as missing even though it resolved correctly in the routed profile.

asyncio.to_thread() is the smallest canonical fix because it retains the non-blocking worker boundary while propagating the current context.

Related Issue

No issue filed.

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 🔒 Security fix
• 📝 Documentation update
• ✅ Tests (adding or improving test coverage)
• ♻️ Refactor (no behavior change)
• 🎯 New skill (bundled or hub)

Changes Made

• Replace the manual compression run_in_executor() call in gateway/slash_commands.py with context-preserving asyncio.to_thread().
• Add a regression test in tests/gateway/test_compress_command.py proving that caller context is visible inside the compression worker.

How to Test

1. Run uv run --extra dev pytest tests/gateway/test_compress_command.py::test_compress_command_preserves_caller_context_in_worker -q.
2. Run uv run --extra dev pytest tests/gateway/test_compress_command.py -q.
3. Run the gateway slash-command test group.

Before the fix, the regression test failed with:

assert [None] == ['profile-secret-scope']

After the fix:

12 passed in 0.45s

The broader gateway slash-command tests also passed: 133 passed.

Checklist

Code

• I've read the Contributing Guide
• My commit messages follow Conventional Commits
• I searched for existing PRs to make sure this isn't a duplicate
• My PR contains only changes related to this fix
• I've run pytest tests/ -q and all tests pass
• I've added tests for my changes
• I've tested on my platform: macOS

Documentation & Housekeeping

• Documentation update: N/A
• cli-config.yaml.example update: N/A
• CONTRIBUTING.md / AGENTS.md update: N/A
• Cross-platform impact considered: asyncio.to_thread() is standard Python and preserves the existing worker-thread behavior
• Tool descriptions/schemas update: N/A

[teknium1]

Thanks for isolating the manual /compress context-loss path. The proposed asyncio.to_thread() change correctly preserves ContextVars while retaining the existing default-executor boundary at gateway/slash_commands.py:3979.

Problems

• The same bug class remains in automatic session-hygiene compression: gateway/run.py:16156-16163 invokes _hyg_agent._compress_context(...) through plain run_in_executor(None, ...). Profile secrets are ContextVar-scoped and fail closed when no scope is present (agent/secret_scope.py:55-57, agent/secret_scope.py:166-174), so this sibling worker needs equivalent propagation.

Suggested changes

• Preserve context for the hygiene compression worker at gateway/run.py:16156 and add a regression test for that path. The existing gateway helper at gateway/run.py:20278-20287 shows the repository's explicit copy_context() executor pattern.

Automated hermes-sweeper review.

[dyreckt]

10-second summary

This PR is the session-hygiene sibling of the manual /compress context fix.

• The manual path is already fixed on main (651c5160b75). This PR originally covered that path too; the commit was dropped as redundant when rebasing onto current main.
• What's left: the hygiene auto-compression worker in gateway/run.py runs through a bare run_in_executor, so the caller's ContextVars are lost on the thread hop. Under gateway.multiplex_profiles the profile secret scope is gone in the worker, and the compressor's aux-client credential resolution fails closed (UnscopedSecretError) — the path the sweeper review flagged.
• The fix: copy_context() + ctx.run on the executor hop — same pattern as main's _run_in_executor_with_context.
• Test: regression test sets a ContextVar in the caller and asserts it reaches the worker. 14 passed locally; CI green on this head.

Related: #76882 closes the other secret-scope residuals (/insights, aux readers, camofox, startup guard); this PR covers the hygiene compression worker.

[teknium1]

Resolved on main: the hygiene run_in_executor hop now runs inside copy_context().run via #100950 (merge c5c9aa8d44), and the manual /compress path already goes through _run_in_executor_with_context on current main. Your July report of the same contextvar-loss class predates both — thanks @dyreckt. Closing as implemented on main.