fix(agents): stop repeat polls of dead PTY sessions

[ousamabenyounes]

Summary

• Track PTY session IDs after write_stdin receives a deterministic PTY session not found result.
• Short-circuit repeated empty polls for the same dead session with a terminal/non-retryable tool result.
• Add regression coverage for the repeated dead-session poll path.

Issue

Fix #867

Test verification (RED -> GREEN)

RED, test-only on upstream main:

$ uv run pytest tests/test_agent_factory_shell.py::test_wrap_write_stdin_blocks_repeat_empty_poll_after_dead_pty
FAILED tests/test_agent_factory_shell.py::test_wrap_write_stdin_blocks_repeat_empty_poll_after_dead_pty
IndexError: pop from empty list

GREEN, after fix:

$ uv run pytest tests/test_agent_factory_shell.py::test_wrap_write_stdin_blocks_repeat_empty_poll_after_dead_pty
1 passed in 2.45s

Additional targeted validation:

$ uv run pytest tests/test_agent_factory_shell.py
4 passed in 2.37s

$ uv run ruff format --check strix/agents/factory.py tests/test_agent_factory_shell.py
2 files already formatted

$ uv run ruff check strix/agents/factory.py tests/test_agent_factory_shell.py
All checks passed!

$ uv run mypy strix/agents/factory.py
Success: no issues found in 1 source file

$ uv run bandit strix/agents/factory.py -c pyproject.toml
No issues identified.

Full-suite baseline comparison:

upstream main: uv run pytest -q -> 2 failed, 339 passed
this branch:   uv run pytest    -> 2 failed, 340 passed

The remaining pytest failures are pre-existing in tests/test_runner_root_prompt.py with AttributeError: 'types.SimpleNamespace' object has no attribute 'runtime'.

Full Ruff baseline comparison:

upstream main: uv run ruff format --check . -> 4 files would be reformatted
this branch:   uv run ruff format --check . -> 4 files would be reformatted

upstream main: uv run ruff check . -> 2 PLC0415 lazy-import errors
this branch:   uv run ruff check . -> 2 PLC0415 lazy-import errors

[greptile-apps]

Greptile Summary

Prevents repeated polling of PTY sessions that have deterministically disappeared.

• Records numeric session IDs returned by write_stdin as not found.
• Short-circuits subsequent empty polls for recorded sessions with a terminal, non-retryable result.
• Adds regression coverage confirming that the underlying tool is invoked only once for repeated dead-session polls.

Confidence Score: 5/5

The PR appears safe to merge, with the dead-session polling behavior covered by a focused regression test.

The cache is confined to the configured write-stdin wrapper, activates only after a string result reports a missing numeric PTY session, and suppresses only later empty polls for that recorded ID; no concrete reachable regression was established.

Important Files Changed

Filename	Overview
strix/agents/factory.py	Adds wrapper-local tracking of missing PTY sessions and suppresses repeated empty polls after a deterministic not-found result; no actionable defect was established.
tests/test_agent_factory_shell.py	Adds focused regression coverage verifying that a repeated empty poll for a known-dead PTY does not invoke the underlying tool again.

_{Reviews (1): Last reviewed commit: "fix(agents): stop repeat polls of dead P..." | Re-trigger Greptile}

[5hy7xz92nd-oss]

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