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audit-feature-interaction

Testing & Quality
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Analyze feature interaction pairs and triples for concurrent defects

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Source SKILL.md: https://github.com/ben-manes/caffeine/blob/HEAD/.claude/skills/audit-feature-interaction/SKILL.md

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Analyze the cache for defects arising from multiple features operating simultaneously on the same entry.

Assume at least one feature interaction bug exists. If your analysis yields zero findings, re-examine the top-priority pairs below — explain specifically why no interleaving produces a bug.

Priority ranking (from confirmed historical bugs):

  1. Refresh + expiration (D+B) — most-bugged interaction historically
  2. Reference collection + any feature (C+*) — value reference visibility
  3. Async completion + any feature (F+*) — future lifecycle edge cases
  4. Eviction + weight change (A+H) — counter drift during transitions

Features: A. Eviction (size/weight limit exceeded) B. Expiration (afterAccess, afterWrite, variable) C. Reference collection (weak key, weak value, soft value GC) D. Refresh (automatic reload) E. Loading (CacheLoader / computeIfAbsent) F. Async completion (CompletableFuture values) G. Listener notification (removal listener, eviction listener) H. Weight change (Weigher returning different weight for new value)

For each pair (A,B), (A,C), ..., (G,H) — 28 pairs total:

  1. Can both features trigger simultaneously on the same entry?
  2. If yes, construct the most adversarial interleaving.
  3. Trace step-by-step: correct processing? notifications? final state? cleanup?

After all pairs, identify highest-risk TRIPLE interactions:

  • Eviction + expiration + listener exception
  • Refresh + async completion + GC collection
  • Weight change + eviction + compute

High-risk pairwise combinations:

  • Eviction during refresh (entry evicted while refreshing)
  • Expiration during compute (entry expires mid-computation)
  • GC during async completion (future completes after weak ref collected)
  • Weight change during eviction
  • Listener exception during any other feature

For each defect: state the features involved, provide the interleaving, state the incorrect behavior.