/fixing-code

description: Fix code defects with a reproducible feedback loop, root-cause diagnosis,
  minimal patch, regression test, and clean verification. Use when debugging, diagnosing,
  or resolving lint/test/build failures. NOT for test-suite cleanup without a production
  bug (use improving-tests), or code review findings without fixes (use reviewing-code).
name: fixing-code

Fix and Diagnose Code

Fix the requested defect or failing gate, one verified root cause at a time. Use the matching `writing-<lang>` skill for toolchain commands. The optional coding-posture plugin owns general debugging and fix procedure; this skill owns the defect evidence and regression contract. Do not load both just to repeat process steps.

Without write access, return proposed changes (file, change, reason) instead of applying them.

Hard rules

• Reproduce the failure when feasible. If it cannot be reproduced, patch only an evidenced contract violation; add regression coverage and report the reproduction gap. Otherwise ask for the missing artifact rather than patching a guess. Ask before adding temporary instrumentation.
• No destructive git (hard reset, clean, force push, checkout over local changes) and no `--no-verify`.
• Never disable assertions, skip fast tests, lower lint severity, or ignore files to make a check pass or run faster. Clear caches only when a stale cache is the diagnosed cause.
• Fix the requested failure first; ask before expanding to unrelated failures.

Outcome

• **Repro**: the fastest reliable failing signal, best a failing test at the behavior seam; otherwise a script, replayed payload, or small harness around the real path. If unavailable, report the gap and use evidenced contract violations instead.
• **Root cause**: traced from the failing boundary to the first bad state or contract mismatch, with evidence (`file:line`, symptom, tool).
• **Regression test** at the seam where the user saw the bug. If only a shallow seam exists, say so rather than adding a fake-confidence helper test.
• Remove temporary probes or promote them to regression tests.
• Browser-only symptoms go to browser-automation unless a cheaper CLI or unit signal exists.
• If a code-graph tool (GitNexus, codegraph) is installed and fresh, use it to find callers or impact before changing widely used code.

Done when the original repro passes, or its absence is reported with the contract evidence and a passing regression test. Report a missing test seam; without a repro, stop rather than patch when regression coverage is unavailable. Relevant build/test/lint checks must pass, or each check that did not run must be named with its reason.

Report

Root cause with evidence, changes (`path:line — fix`), and each check with pass, fail, or skipped and why. If blocked, name the missing artifact, access, or approval.

Platform additions

No target-specific additions.