docs(spec-grill): make Goal observability check explicit outside the 3-axis test

[sungjunlee]

Dogfooding finding (2026-05-23, PR #110; reduced scope 2026-05-31).

spec-grill now applies the 3-axis predicate test to Behaviors and Hard Constraints, and the Goal step already says a Goal should be an observable user/operator outcome. The remaining gap is explicit wording that Goals are not 3-axis predicates.

Goals are observable outcomes, not verifiable predicates. Forcing Goals through the 3-axis test produces awkward, over-precise prose.

Scope

Update skills/spec-grill/SKILL.md and/or skills/spec-grill/references/capabilities.md with the Goal check.

Proposed rule

• Behaviors and Hard Constraints must pass the 3-axis predicate test.
• Goals use a lighter check: can a user or operator observe this outcome in plain language without instrumentation?
• If yes, the Goal is committable.
• If no, sharpen the Goal, but do not force it through authority / distributional / manipulability axes.

Acceptance Criteria

• spec-grill docs explicitly state that Goals are outside the 3-axis predicate test.
• Goal-line check is documented as plain-language observability.
• Wording uses current spec-grill / spec/capabilities.md names, not retired backlog-charter paths.

[coderabbitai]

🔗 Related PRs

#99 - docs(backlog-charter): add good/bad verifiable-predicate examples (#95) [merged]
#110 - docs: dogfood spec/capabilities.md for dev-backlog itself (#105) [merged]
#160 - [codex] split spec charter and grill skills [merged]

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!

[sungjunlee]

2026-05-31 triage update: reduced scope. The current spec-grill SKILL already applies the 3-axis test only to Behaviors and Hard Constraints, and its Goal step says the Goal is an observable user/operator outcome. Keep this open only for the missing explicit wording: Goals are not 3-axis predicates; accept a Goal when it is observable in plain language without instrumentation, otherwise sharpen it. This is a small clarification, not a new design change.