fix(agent): unrunnable pipeline.buildCommand kills the task pre-agent while a build timeout degrades gracefully

[srbhsrkr]

Component

Agent (Python runtime)

Describe the bug

A pipeline.buildCommand whose executable does not exist in the agent container raises FileNotFoundError out of the pre-agent baseline build and kills the task before the agent ever runs. The surrounding code goes to considerable lengths to handle the analogous timeout case gracefully, so this looks like an oversight rather than a deliberate choice.

agent/src/repo.py:457-473:

try:
    result = run_cmd(build_argv, label="verify-build-pre", ..., timeout=BUILD_VERIFY_TIMEOUT_S, stream=True)
except subprocess.TimeoutExpired:
    log("WARN", f"Initial build ({build_cmd_str}) did not finish within ...  skipping baseline (not a regression)")

The comment above that block explains the reasoning for the timeout path at length — "a timeout means 'no usable baseline', NOT 'the agent broke it', so we treat it as no-known-regression and let the run proceed" — and notes that without the guard the task would "crash the whole task BEFORE the agent ever ran, so the issue got no PR and sat in Backlog — indistinguishable from a real failure."

A missing binary produces exactly that outcome, because only TimeoutExpired is caught.

Expected behavior

An unrunnable build command should be treated the same way as a timeout: log a warning, record "no usable baseline", and let the agent run. The misconfiguration should be surfaced on the PR (and ideally as an inert-gate note), not converted into a task failure.

Current behavior

The task dies during hydration with build_passed=null and no PR. Observed on task 01KZS2MS1BG7TDXHR7CDNMYM0A:

status        = FAILED
build_passed  = null
error_message = FileNotFoundError: [Errno 2] No such file or directory: 'pytest'

Total time to failure: ~20 seconds. The agent never started, so a single typo in a blueprint's buildCommand bricks every task against that repo until someone redeploys.

Reproduction steps

1. Onboard a repo with a pipeline.buildCommand naming a binary not present in the agent image, e.g. buildCommand: 'pytest tests/unit/' (the agent container's PATH leads with /app/.venv/bin, built uv sync --frozen --no-dev per agent/Dockerfile:104, so there is no pytest).
2. Submit any coding task against that repo.
3. Task fails in ~20s at hydration with the FileNotFoundError above; no PR, no agent turns.

Possible solution

Catch FileNotFoundError (and likely PermissionError/NotADirectoryError) alongside subprocess.TimeoutExpired in both the pre-agent baseline (agent/src/repo.py:457) and the post-agent gate (agent/src/post_hooks.py:187), mapping them onto the existing inert-gate path rather than a task failure — an unrunnable command verified nothing, which is the definition of inert already handled elsewhere in pipeline.py:1435-1441.

Arguably a misconfigured blueprint should also surface a distinct, non-retryable error classification so the operator knows to fix the blueprint rather than retry.