[Bugfix #1142] Expose exitCode to cron conditions; let condition-true failure runs deliver alerts

[waleedkadous]

Summary

Fixes the two-layer bug in tower-cron.ts where (1) conditions referencing exitCode threw ReferenceError on every run, and (2) failure runs could never deliver alerts — making "alert me when this command fails" inexpressible.

Root Cause

• evaluateCondition() built new Function('output', 'return ' + condition) — only output was in scope, so condition: "exitCode != 0" threw ReferenceError every run (12k+ WARN lines in a real tower.log). The catch forced shouldNotify = false.
• runCommand() rejected on any non-zero exit, so the exit code was never available as data.
• The delivery gate if (shouldNotify && result === 'success') suppressed delivery on exactly the runs a monitoring task cares about.

Fix

• runCommand() resolves { output, exitCode }. A plain non-zero exit (numeric error.code, no kill signal) resolves with that exit code — it's data, not an error. Spawn failures and timeout/kills still reject, reported as exitCode -1 / 124 respectively.
• evaluateCondition(condition, output, exitCode = 0) exposes both variables to the condition. Output-only conditions are unchanged.
• Delivery gate: a task with a condition delivers exactly when the condition is truthy (including failed runs). A task without a condition keeps today's behavior — deliver only on exit 0 — so existing tasks don't start alert-spamming on flaky commands. Non-delivering failures keep the WARN log.
• last_result in cron_tasks still records success/failure by exit code — only delivery logic changed.
• Docs: the condition environment (output: string, exitCode: number) is now documented in the afx skill's ## afx cron section and a new ### afx cron section in agent-farm.md, in BOTH trees (instance + skeleton).

Test Plan

• 8 new regression tests in tower-cron.test.ts (34 total, all pass):
  • exitCode != 0 condition delivers on non-zero exit, no ReferenceError
  • exitCode != 0 condition does not deliver on clean exit
  • no-condition task does not deliver on non-zero exit (regression)
  • output-only conditions unchanged alongside exitCode (regression)
  • timeout reported as exitCode 124 — condition can still fire; without a condition it stays WARN-only
  • evaluateCondition unit coverage for exitCode scope + default
• Full suite: 3440 passed, 48 pre-existing skips. Root pnpm build passes.

Fixes #1142

🤖 Generated with Claude Code

[waleedkadous]

Architect Review

Nice, tight execution — this carries the issue's prescribed design faithfully, and the docs work goes beyond the ask in a good way.

Low-risk change (production diff is 37/22 in one file, tower-cron.ts; the rest is 204 lines of regression tests + doc sync in both trees). Verified against the issue:

• runCommand resolves {output, exitCode} for plain non-zero exits (exit code is data), still rejects only for spawn failure and timeout/kill — with the coreutils-style 124/-1 mapping in the catch. ✓
• evaluateCondition(condition, output, exitCode = 0) — backward-compatible default, output-only conditions untouched. ✓
• Delivery gate: condition-bearing tasks deliver on the condition alone; no-condition tasks keep exit-0-only delivery (no alert-spam regression). ✓
• last_result still records success/failure by exit code. ✓
• Docs: full .af-cron YAML format + condition environment documented in the afx skill AND agent-farm.md, both trees — the skeleton's agent-farm.md previously had no cron section at all, so this fills a real gap. ✓

One intentional semantic change worth naming for the record (it's documented, and correct): an output-only condition that evaluates true on a failed run now delivers, where before failure suppressed everything. That's the point of the fix — "condition alone decides" — just noting it's a behavior change for pre-existing condition-bearing tasks, not a pure bugfix.

CMAP unanimous (3× APPROVE/HIGH), CI 6/6 green.