debug-my-harness

Diagnose harness misbehavior from the flight recorder — the local, append-only ledger
at .vigiles/runs.jsonl that vigiles writes as your harness runs. It records what actually
happened, so you debug from evidence instead of guessing.

What's in the ledger

One JSON record per line, each with a kind:

• hook — a compiled-hook gate decision: {event, decision: allow|deny|ask, mode: enforce|observe, rule, cmd, reason}.
• agent — a subagent tool-contract decision: {name, tool, allowed, reason} (a false = the agent went outside its lane).
• skill — a skill activation: {name, fired}.
• eval — a measured metric: {name, metric, value} (e.g. trigger-rate recall/precision).
• capability-diff — a blast-radius change: {pr, added, removed, widened}.

Instructions

Step 1: Read the ledger

Read .vigiles/runs.jsonl (JSONL — one record per line; tolerate a torn last line). If it's
absent or empty, say so — there's nothing recorded yet; suggest running the harness (or
vigiles audit) first. Do NOT fabricate records.

Step 2: Answer the specific question, evidence-first

Match the user's question to the ledger:

• "Why did skill X stop firing / why does the wrong one run?" — count skill fires by
  name over time. If X's fire-rate dropped, look for a sibling that fired on the same kinds
  of prompts (a selection collision) and check their descriptions for overlap. Recommend
  differentiating or merging the descriptions.
• "Why didn't my hook block that?" — find hook records for the event. A decision: allow on something that should be denied, or mode: observe (shadow, never blocks), or
  the absence of any record, tells you which. Recommend flipping observe→enforce or
  fixing the gate logic.
• "Did a subagent misbehave?" — list agent records with allowed: false: the agent
  reached for a tool outside its declared contract. Point at the contract to tighten or widen.
• "Is it getting worse?" — compare eval metric values (recall/precision) across runs;
  a downward trend is drift (often after a harness/model upgrade).

Step 3: Recommend a fix, tied to the evidence

Prefer promoting an ignored-but-decidable rule from prose to a deterministic gate: a
repeated agent violation or a rule the agent keeps breaking → a compiled hook or a tighter
tool-contract (the strengthen skill can help). A description collision → differentiate the
skill descriptions. Always cite the specific records you based the diagnosis on.

Step 4: Offer the next step

If the fix is a spec change, hand off to edit-spec. If it's promoting guidance to a linter
rule, hand off to strengthen. If a behavioral claim needs measuring (does the skill fire
now?), hand off to test-harness (measureTriggerRate).