diff --git a/packages/extension/skills/autoresearch/SKILL.md b/packages/extension/skills/autoresearch/SKILL.md
index 301a3781..fa047dcc 100644
--- a/packages/extension/skills/autoresearch/SKILL.md
+++ b/packages/extension/skills/autoresearch/SKILL.md
@@ -18,8 +18,12 @@ vault_contract:
 > is the `autoresearch` primary agent card).
 
 **Entry points:** the `autoresearch` primary agent (Tab-switch into research mode —
-its prompt embeds this spine), direct invocation of this skill, or the standing line in
-the user's autoresearch kickoff prompts. All three lead here; this file is the protocol.
+its first action invokes the `director-core` skill, the canonical loop protocol),
+direct invocation of this skill, or the standing line in the user's autoresearch
+kickoff prompts. All three lead here; this skill is the research-mode instantiation —
+it carries what director-core deliberately does not (the spec-gate review budget, the
+checkout registry, the probe/experiment boundary). Where this file and director-core
+appear to conflict, director-core wins; report the conflict, never resolve it by edit.
 
 The operating principle: **the context window is a cache; the vault is the database.**
 Every piece of load-bearing state lives in a vault note; the context window holds only the
diff --git a/packages/extension/test/fixtures/internal-skill-registry.json b/packages/extension/test/fixtures/internal-skill-registry.json
new file mode 100644
index 00000000..7dee890f
--- /dev/null
+++ b/packages/extension/test/fixtures/internal-skill-registry.json
@@ -0,0 +1,5 @@
+[
+  "develop",
+  "director-core",
+  "implement-issue"
+]
diff --git a/packages/extension/test/skill_reference_closure.test.ts b/packages/extension/test/skill_reference_closure.test.ts
new file mode 100644
index 00000000..219744fc
--- /dev/null
+++ b/packages/extension/test/skill_reference_closure.test.ts
@@ -0,0 +1,101 @@
+// Skill-reference closure (#537) — every skill-invocation directive in the
+// agent cards must resolve against the repo's public skills plus a committed
+// registry of internally-homed skills. Born from the 2026-08-23 outage: both
+// mode cards' first action invokes `director-core`, but the server's staging
+// allowlist omitted it, and runtime died with "skill director-core
+// unavailable". CI must catch what staging forgot.
+import { describe, it, expect } from "vitest";
+import { readFileSync, existsSync, readdirSync } from "node:fs";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+const HERE = path.dirname(fileURLToPath(import.meta.url));
+const EXT = path.join(HERE, "..");
+const AGENTS_DIR = path.join(EXT, "agents");
+const SKILLS_DIR = path.join(EXT, "skills");
+const REGISTRY_PATH = path.join(HERE, "fixtures", "internal-skill-registry.json");
+
+// The live armonissima team mount — canonical home of the registry's skills;
+// absent on machines without the mount (same conditional as mode_cards.test.ts).
+const ARMONISSIMA_SKILLS = path.join(
+  process.env.HOME ?? "",
+  ".amico",
+  "vaults",
+  "armonissima",
+  "skills",
+);
+
+const registry: string[] = JSON.parse(readFileSync(REGISTRY_PATH, "utf8")) as string[];
+
+/**
+ * Skill-invocation directives in a card: "the `X` skill", "invoke the `X`",
+ * "invoke the **`X`**". Deliberately narrow — this is an invocation contract,
+ * not every mention.
+ */
+function skillDirectives(text: string): string[] {
+  const names = new Set<string>();
+  for (const m of text.matchAll(/`([a-z][a-z0-9-]+)`\s+skill\b/g)) names.add(m[1]!);
+  for (const m of text.matchAll(/invoke the (?:\*\*)?`([a-z][a-z0-9-]+)`/gi))
+    names.add(m[1]!);
+  return [...names];
+}
+
+const cards = readdirSync(AGENTS_DIR).filter((f) => f.endsWith(".md"));
+
+// Repo public skills + the committed internal registry = the resolvable set.
+const repoSkills = readdirSync(SKILLS_DIR).filter((f) =>
+  existsSync(path.join(SKILLS_DIR, f, "SKILL.md")),
+);
+const resolvable = new Set<string>([...repoSkills, ...registry]);
+
+describe("skill-reference closure — agent card directives resolve", () => {
+  it("the card set is non-empty (guard against a vacuous suite)", () => {
+    expect(cards.length).toBeGreaterThan(0);
+  });
+
+  it("cards carry at least one skill directive (guard against a vacuous scan)", () => {
+    const all = cards.flatMap((c) =>
+      skillDirectives(readFileSync(path.join(AGENTS_DIR, c), "utf8")),
+    );
+    expect(all.length).toBeGreaterThan(0);
+  });
+
+  for (const card of cards) {
+    it(`${card}: every skill directive resolves`, () => {
+      const text = readFileSync(path.join(AGENTS_DIR, card), "utf8");
+      const directives = skillDirectives(text);
+      for (const name of directives) {
+        expect(
+          resolvable.has(name),
+          `${card} invokes "${name}" — not in repo skills nor the internal registry`,
+        ).toBe(true);
+      }
+    });
+  }
+});
+
+describe("skill-reference closure — internal registry", () => {
+  it("the registry is non-empty and duplicate-free (guard against a vacuous check)", () => {
+    expect(registry.length).toBeGreaterThan(0);
+    expect(new Set(registry).size).toBe(registry.length);
+  });
+
+  it("registry entries are not shadows of repo skills (registry = internal-only)", () => {
+    for (const name of registry) {
+      expect(
+        repoSkills.includes(name),
+        `"${name}" exists in repo skills — remove it from the internal registry`,
+      ).toBe(false);
+    }
+  });
+
+  it("every registry entry exists in the team mount when the mount is present", () => {
+    if (!existsSync(ARMONISSIMA_SKILLS)) return; // mount absent: registry is the record
+    for (const name of registry) {
+      expect(
+        existsSync(path.join(ARMONISSIMA_SKILLS, name, "SKILL.md")),
+        `registry entry "${name}" has no SKILL.md in the armonissima mount`,
+      ).toBe(true);
+    }
+  });
+});