# BF-246 LLM Tier Recovery Health Probe Build Report

**Date:** 2026-04-29
**Status:** Complete
**Prompt:** `prompts/bf-246-llm-tier-recovery-deadlock.md`
**Builder:** GitHub Copilot

## Files Changed

- `src/probos/cognitive/llm_client.py`
  - Added stored health probe task attributes, start/loop/stop methods, transition emission, and close-time cancellation.
- `src/probos/config.py`
  - Added `SystemConfig.health_probe_interval_seconds` with a `>= 5.0` validator.
- `src/probos/startup/finalize.py`
  - Wired the LLM health probe at startup with public `runtime.emit_event`.
- `tests/test_bf246_llm_health_probe.py`
  - Added 9 focused BF-246 tests.
- `PROGRESS.md`, `docs/development/roadmap.md`
  - Updated BF-246 tracking.
- `prompts/build-reports/bf-246-llm-tier-recovery-deadlock-build.md`
  - Added this build report.

## Sections Implemented

- `### Section 1: Add health probe to OpenAICompatibleClient.__init__ and methods` - added `_health_probe_task`, `_health_probe_emit`, `start_health_probe()`, `_health_probe_loop()`, `stop_health_probe()`, and `close()` cancellation.
- `### Section 2: Add health_probe_interval_seconds to config` - added root `SystemConfig.health_probe_interval_seconds` and validator rejecting values below `5.0`.
- `### Section 3: Wire the health probe at startup` - started the probe in `finalize_startup()` and passed public `runtime.emit_event` as the emitter.
- `### Section 4: Verify shutdown cancellation` - verified shutdown calls `runtime.llm_client.close()` in `src/probos/startup/shutdown.py`; `close()` now cancels the probe.
- `## Tests` - implemented all 9 requested tests in `tests/test_bf246_llm_health_probe.py`.
- `## Tracking` - updated project trackers and this build report.

## Post-Build Section Audit

- `## Problem`, `## Prior Art`, `## Root Cause`, and `## Why This Works` - addressed by adding a request-flow-independent probe while preserving fallback skip and BF-240 dwell-time logic.
- `### Section 1` - implemented in `llm_client.py`.
- `### Section 2` - implemented in `config.py`.
- `### Section 3` - implemented in `startup/finalize.py`.
- `### Section 4` - shutdown close path verified and covered by `test_close_cancels_probe`.
- `## Tests` - all 9 test cases implemented.
- `## What This Does NOT Change` - no dwell-time, fallback skip, proactive loop, or event dataclass changes.
- `## Tracking` - trackers updated.
- `## Acceptance Criteria` - focused and adjacent regression gates passed; full serial suite deferred to final sweep gate per 2026-04-29 revised execution instruction.

## Tests

- `d:/ProbOS/.venv/Scripts/pytest.exe tests/test_bf246_llm_health_probe.py -v -n 0`
  - Result: 9 passed.
- `d:/ProbOS/.venv/Scripts/pytest.exe tests/test_config.py tests/test_llm_client.py tests/test_bf069_llm_health.py -q -n 0`
  - Result: 78 passed.

## Deviations from Prompt

- `_health_probe_loop()` re-raises `asyncio.CancelledError` rather than returning, preserving the repository async cancellation discipline while `stop_health_probe()` still awaits and handles task cancellation.
- Full-suite `-n 0` is being reserved for the final sweep gate per the revised execution instruction because xdist is known to produce environmental failures and serial full-suite runs are slow.
