types(acp): add missing parameter type annotations

[github-actions]

Summary

Add type annotations to parameters that were missing types in the ACP module.

Changes

• test_utils.py: Add IO[bytes] type annotation for stdout parameter in UnbufferedJsonRpcReader.__init__()
• token_streamer.py: Add Any type annotation for tool_call parameter in _handle_tool_call_streaming() (uses dynamic attribute access via getattr)

Related Issue

Addresses findings from #751

Testing

• Linting passes (make lint)
• Tests pass (make test - 1353 tests)

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This PR was automatically generated by the Code Quality Report workflow.

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🚀 Try this PR

uvx --python 3.12 git+https://github.com/OpenHands/OpenHands-CLI.git@fix/code-quality/add-return-type-hints

[enyst]

@OpenHands make an empty commit to kick off CI and /iterate to green and approved by the AI reviewer from pr-review workflow.

[openhands-ai]

I'm on it! enyst can track my progress at all-hands.dev

[all-hands-bot]

🟢 Good taste - Clean, focused type annotation additions.

Both annotations are correct:

• IO[bytes] for stdout is appropriate for the file-like object used with fileno()
• Any for tool_call is justified given the dynamic attribute access via getattr

[RISK ASSESSMENT]

• [Overall PR] ⚠️ Risk Assessment: 🟢 LOW

Type annotations in Python are purely for static analysis and have zero runtime impact. No behavior changes, no breaking changes, no security implications.

VERDICT:
✅ Worth merging: Improves type safety with zero risk.

KEY INSIGHT:
Using Any for dynamically-accessed objects is the pragmatic choice that preserves type checking elsewhere without forcing rigid type definitions where they don't fit.

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Workflow run: https://github.com/OpenHands/OpenHands-CLI/actions/runs/26401712227

[github-actions]

Coverage Report •

File	Stmts	Miss	Cover	Missing
openhands_cli/acp_impl/events
token_streamer.py	125	11	91%	149, 161, 165, 168, 173, 175, 177, 179, 244, 251, 271
TOTAL	7062	1011	85%

[openhands-ai]

Since my last summary, there have been no additional changes or actions.

• ✅ The requested PR work was fully addressed: an empty commit was pushed, CI was triggered, checks went green, and the AI reviewer approved the PR.
• ✅ All instructions were followed faithfully, including using the GitHub API/CLI, pushing only to the PR branch, and verifying final status.
• ✅ The changes were concise: only the requested empty commit was added; no code or unrelated files were modified.
• ✅ No extraneous changes need to be reverted.