Skill: api/compatibility-check

Purpose

Determine whether an API change is:

• backward-compatible
• conditionally compatible
• breaking

And make that status explicit before shipping.

---

Inputs

• Old contract
• New contract
• Known consumers (if available)

---

Outputs

• Compatibility assessment:
  • compatible / breaking / unsafe
• Explicit list of breaking changes (if any)
• Recommendation:
  • proceed
  • version
  • block

---

Non-goals

• Modifying contracts
• Updating clients
• Implementing migrations

---

Workflow

1. Compare old vs new contract shapes.
2. Identify removed or behaviorally changed fields.
3. Assess consumer impact.
4. Emit a clear compatibility verdict.

---

Checks

• All removals and type changes enumerated
• Verdict is explicit and justified

---

Failure modes

• Missing baseline contract → block and request one.
• Ambiguous change → recommend meta/spec-sculptor.

---

Telemetry

Log:

• skill: api/compatibility-check
• verdict
• affected_consumers
• outcome