Deep Debug Skill

Adversarial hypothesis-driven debugging. Given a bug, generate competing hypotheses across orthogonal dimensions, judge each independently (two-pass blind), run discriminating probes that falsify the weaker, fix the survivor with test-first discipline, and escalate to architectural review after 3 failed attempts. Output is a verified fix with a failing-test-now-passes proof, OR an honest termination label naming why the bug resisted a code-level fix.

Execution Model

All operations use Claude Code primitives. These contracts are non-negotiable:

• All data passed to agents via files, never inline. Evidence, hypothesis lists, probe specs, known-hypothesis IDs — all written to disk before the agent prompt. Inline data is silently truncated.
• State written before agent spawn, not after. spawn_time_iso is written to state.json before the Agent tool call. Spawn failure records spawn_failed status. Resume uses persisted state, never in-memory reconstruction.
• Structured output is the contract; free-text is ignored. Every judge, probe-verdict, and validator produces machine-parseable structured lines. Coordinator reads only structured fields. Unparseable output triggers fail-safe classification (disputed, never rejected). Hypothesis output files MUST contain STRUCTURED_OUTPUT_START/STRUCTURED_OUTPUT_END markers; files without these markers are treated as failed.
• No coordinator self-review of anything load-bearing. Hypothesis plausibility, evidence tier, rebuttal verdicts, probe winner classification — all delegated to independent agents. The coordinator orchestrates; it does not evaluate.
• Termination labels are honest. One of 7 defined labels. Never "probably fixed," never "looks right," never "no critical bugs remain." A fix is Fixed — reproducing test now passes only when the failing test exists, passes with the change, and the full suite is clean.
• Hard ceilings are absolute. max_cycles = 3, max_probes_per_cycle = 3, fix_attempt_count ≤ 3. Three fix attempts is evidence the hypothesis space is wrong — Phase 7 architectural escalation is mandatory, never optional.

Shared contracts: this skill inherits the four execution-model contracts (files-not-inline, state-before-agent-spawn, structured-output, independence-invariant) from _shared/execution-model-contracts.md. The items listed above are the skill-specific elaborations; the shared file is authoritative for the base contracts.

Pressure awareness: this skill applies the pressure circuit breakers from _shared/pressure-awareness.md. After 3 probes with no hypothesis falsification, regenerate the hypothesis space rather than probing a 4th time. The existing max_cycles = 3 and fix_attempt_count ≤ 3 ceilings serve as the same-approach ceiling; this contract adds the diminishing-returns check between probe cycles.