fix: replace assert with runtime guards in tools/ and plugins/ (6 sites)

[JonthanaHanh]

Summary

Replace assert statements with explicit runtime guards in 5 files (6 sites) across tools/ and plugins/. Assert statements are stripped by python -O, silently removing invariant checks in production.

Changes

File	Line	Old	New
tools/tts_tool.py	3597	assert streamer is not None	if streamer is None: return
tools/tts_tool.py	3704	assert streamer is not None	if streamer is None: return
tools/computer_use/doctor.py	226	assert proc.stdin is not None and proc.stdout is not None	if ... raise RuntimeError(...)
tools/computer_use/browser_route.py	481	assert selected_tab is not None and self.state.target_id is not None	if ... return _refusal(...)
hermes_cli/session_recovery.py	1281	assert output is not None	if ... raise SessionRecoverySourceError(...)
plugins/platforms/buzz/adapter.py	131	assert spec is not None and spec.loader is not None	if ... raise ImportError(...)

Guard Selection Rationale

• tts_tool.py: _playback_worker and _enqueue_audio are closures where streamer is captured from the enclosing scope. Early return is the safest guard — if streamer is somehow None, the function has nothing to do.
• doctor.py: _mcp_rpc needs both stdin and stdout pipes to communicate with the MCP subprocess. RuntimeError is appropriate since this is a precondition for the function.
• browser_route.py: Returns a _refusal response matching the existing error pattern in this file — keeps the browser action pipeline consistent.
• session_recovery.py: Raises SessionRecoverySourceError which is the existing exception type for this module's error paths.
• buzz/adapter.py: Raises ImportError since the assert guards an importlib loading operation.

Test Plan

• python3 -c "import ast; ast.parse(open(f).read())" passes for all 5 files
• Existing tests pass (no behavioral change — guards only activate under python -O or edge-case None values)

[spfcraze]

This was generated by AI during triage.

Summary:
All six assert sites converted in this PR already carry open conversions in sibling PRs — #76617, #77778, #80861, and #80910 together cover every one — so this PR re-files conversions the series already carries.

Problems:

• hermes_cli/session_recovery.py, plugins/platforms/buzz/adapter.py, and tools/computer_use/browser_route.py are converted in open PR fix: replace assert statements with runtime guards (4 files) #76617, with fix: replace assert with runtime guards in buzz adapter and session recovery #77778 covering the first two again, fix: replace assert with runtime guards in computer_use (browser_route, doctor) #80861 covering browser_route and tools/computer_use/doctor.py, and fix: replace assert with runtime guard in tts_tool streaming playback #80910 covering both tools/tts_tool.py sites.
• The same session_recovery assert is converted in five open PRs — fix: replace assert with runtime guard in session recovery #73050, fix: replace assert statements with runtime guards #73800, fix: replace assert statements with runtime guards (4 files) #76617, fix: replace assert with runtime guards in buzz adapter and session recovery #77778, and this one.

Solution:
The six conversions already exist across the open series; carrying them in the siblings (#76617, #77778, #80861, #80910) instead of a parallel PR keeps each assert site to a single open conversion.

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Checked against 9f55696 — the tip of fix/assert-runtime-guards-tools-plugins when this was written.