/diagnose
Diagnose a defect before fixing. Reproduce the failure first (Step 0), then Is/Is Not, then Five Whys, then a Hypothesis. Run before writing any fix code. Lazy diagnosis ships brittle fixes.
/diagnoseType it bare, or paste it with loose context after — Claude figures out the rest.
Bugs get fixed on guesses. The wrong cause gets patched. The class comes back a week later.
A short trace from failure to root cause. You fix the class once instead of the instance three times.
Takes in
- A failing test or error log
- A bug ticket or screenshot
Returns
- Reproduce step
- Is/Is Not table
- Five Whys chain
- Hypothesis with a read-only test
What it does
Structured defect diagnosis. Run /diagnose before writing any fix code. I walk you through 7 steps:
The output separates "I fixed it" from a real cure. Without a repro, "I fixed it" has no counterpart. The repro is the surface every next step operates on.
Read the full skill
The complete instructions live at .claude/skills/diagnose/SKILL.md in your repo after bassclef-sync. Open with your editor for phases, rules, and worked examples.
Where in the SDLC
Also relevant in: Test, Ship.
Why this phase: Fires before writing any fix code. Any observed failure.
Related
- Skills catalog — browse all skills grouped by lifecycle phase
- Tier system — what each tier gives you
FAQ
Terms from bassclef vocabulary that appear on this page.
- load-bearing
- A part of the system that other parts depend on — remove it and downstream things break. Bassclef uses the word for artifacts that other artifacts read: a canvas is load-bearing when a spec cites it, a spec is load-bearing when Builder uses it. Plain equivalent: 'actually used' or 'counted on'.
- hook
- A shell script bassclef wires into Claude Code's tool-invocation lifecycle. Hooks fire at events like PreToolUse (before an Edit lands) or SessionStart (when a session opens). Hooks enforce rules mechanically — a rule says 'don't do X'; a hook fires and BLOCKs if X happens.
- rule
- A markdown file auto-loaded into every session's context. Rules pin discipline the agent applies to every response (plain-English writing, blocked-items protocol, temperance gates). Different from a hook — rules are steering; hooks are enforcement.
- skill
- A user-invocable command (like `/kiss` or `/temperance`) that runs a specific bassclef workflow. Every skill lives at `.claude/skills/<name>/SKILL.md` with frontmatter + procedure. Adopters type the slash command; Claude Code loads the skill and runs it.
- bassclef-upstream
- The private repo where bassclef substrate is authored. Ships to a public `bassclef` npm package + a public `bassclef-web` docs site. Adopters read the public tier; the operator maintains upstream.
Shipped by @kingofrock · Read the essays
/build
Take a plan from /launch and ship it. One builder per user story. Runs /verify. Opens PRs. Gates prod on a human. Refuses auth, schema, security, and tenant work. Two modes — full and degrade-with-note.
/pattern-review
Review code through the lens of world-class engineering patterns — GoF, Fowler, SOLID, DDD. Flag violations and suggest improvements. Complements /architect-review which is system-level.