diff --git a/design/INDEX.md b/design/INDEX.md
index 7fe92c9..78bdf0c 100644
--- a/design/INDEX.md
+++ b/design/INDEX.md
@@ -78,7 +78,7 @@ is the default.
 ## Contracts
 | id | consumer / lifetime | ratifying-test | link |
 |----|---------------------|----------------|------|
-| feature-acceptance   | brainstorm-gate / stable      | skills/brainstorm/SKILL.md         | design/contracts/0004-feature-acceptance.md |
+| feature-acceptance   | brainstorm-gate / stable      | CLAUDE.md                          | design/contracts/0004-feature-acceptance.md |
 | authoring-surface    | LLM author / stable           | crates/ailang-surface/tests/round_trip.rs       | design/contracts/0001-authoring-surface.md |
 | roundtrip-invariant  | every release / stable        | crates/ailang-surface/tests/round_trip.rs       | design/contracts/0009-roundtrip-invariant.md |
 | language-constraints | LLM author / stable           | crates/ailang-check/src/uniqueness.rs (in-source mod tests) | design/contracts/0015-language-constraints.md |
diff --git a/design/contracts/0004-feature-acceptance.md b/design/contracts/0004-feature-acceptance.md
index 1491f1d..8f5c345 100644
--- a/design/contracts/0004-feature-acceptance.md
+++ b/design/contracts/0004-feature-acceptance.md
@@ -73,4 +73,7 @@ Empirically: if a feature is proposed and the LLM does not produce it
 in unprompted code samples, the feature is proposed for the wrong
 reason. The orchestrator's job is to notice that and cut.
 
-Ratified by: `skills/brainstorm/SKILL.md`.
+Ratified by: `CLAUDE.md` § "Feature acceptance: LLM utility"
+(in-tree project discipline). The brainstorm skill, which lives in
+the `~/dev/skills/` plugin outside the repo, applies this criterion
+at spec time.