go-systematic-debugginglisted

# Go Systematic Debugging Use [Implementation / Validation / Closeout](../../../docs/spec-first-workflow/phases/implementation-validation-closeout.md) for authorized repair. Work causally: classify `diagnosis_only` or `fix_authorized`, reconstruct the affected invariant and hypothesis set from the symptom, volatile evidence, callers, state transitions, and sibling paths, then reproduce with controls and trace to the first broken invariant. Match the observed symptom to [the reference selector](references/index.md) and load one reference only when it can change the next discriminating experiment or repair owner. Test the highest-information hypothesis one at a time and disposition it as rejected, supported, or blocked; continue until one causal chain is supported by reproduction or current incident evidence and survives the smallest available falsification, or a named blocker prevents the next experiment. In `fix_authorized`, the repair gate opens only after that diagnosis observable exists; repair only the earliest owner and replay the signal. Route accepted feature work to `go-coder`; hand timeout, retry, degradation, or overload policy to `go-reliability`. Return evidence, hypothesis dispositions, the supported root cause or explicit unproven state, results, and the next experiment or blocker. Missing causal proof keeps diagnosis open and cannot justify repair.