blindspot

name	blindspot
description	Use before modifying unfamiliar or high-stakes code — when the user invokes /blindspot, inherits a module or codebase, asks "what am I missing?", or is about to change auth, billing, data migration, or concurrency code they didn't write. Not for routine changes in well-understood code.

Blindspot

Hunt unknown unknowns: the risks nobody thought to ask about. Output is a short ranked set of blindspot cards, each grounded in this codebase with a concrete next move — never a generic risk checklist.

Steps

1. Map the territory. Read the target module, its callers, its tests, and its config/env wiring. Blindspots live in the connections, not the file itself.
2. Sweep the classic hiding places against the actual code:
   • Hidden state and side effects (module-level mutables, caches, singletons)
   • Implicit invariants the code assumes but never checks (ordering, uniqueness, non-null)
   • Swallowed errors: catch blocks that hide failure, fallbacks that mask bugs
   • Concurrency and ordering: races, double-fires, retry without idempotency
   • Config/env coupling: behavior that changes across environments
   • AuthZ edges: who else can reach this path, what happens unauthenticated
   • Back-compat and migration traps: persisted data shaped by old code
3. Write blindspot cards. Each card:
   • What you likely don't know — one sentence
   • Evidence — file:line in this repo (no evidence, no card)
   • How it bites — the concrete failure scenario
   • Next move — a question to answer or a copyable fix prompt
4. Rank and cap. Order by blast-radius × likelihood. Max 7 cards — if you found 20, the bottom 13 are noise.
5. Hand off. If the user wants fixes, feed the cards into normal implementation flow (interview first if a card exposes a real decision).

Common mistakes

• Generic risks not grounded in this code ("consider adding error handling") — every card cites file:line or gets cut.
• Restating known unknowns the user already raised — the job is what they didn't ask.
• 20-card dumps — capping at 7 forces the ranking that makes the output usable.
• Reading only the target file — the callers and tests are where assumptions break.