Spec Failure Domain Analysis

Run this skill during spec review to catch common omissions before implementation.

When to Use

• After drafting FR/NFR/StR requirements
• Before spec-to-plan (part of its readiness gate)
• During peer review of specifications

Checklist

1. Extension Points (Trust Boundaries)

For each callback, hook, observer, or plugin interface:

• Is failure behavior defined? Options:
  • Strict: Failure aborts operation (data integrity)
  • Resilient: Failure is logged/suppressed (availability)
  • Configurable: User chooses policy

2. Entity Identity

For each core domain entity (State, Event, User, etc.):

• Is the uniqueness key explicit?
  • Bad: "A set of states"
  • Good: "States unique by name property"

3. Evaluation Purity

For each user-supplied logic (guards, filters, validators):

• Are side-effects constrained?
  • Document if read-only is required for simulation/reasoning

4. Topological Robustness

For each graph/tree algorithm (search, path-finding):

• Is termination guaranteed on cycles?
• Are worst-case structures considered? (deep nesting, disconnected nodes)

Output

Document any missing constraints as proposed additions:

• NFR: Non-functional (resilience, performance)
• StR: Structural (integrity, purity)
• FR: Functional (if behavior is undefined)