refactor(flags): migrate external skills flag (#27685)

packages/opencode/test/skill/skill.test.ts

@@ -29,6 +29,19 @@ const itWithoutClaudeCodeSkills = testEffect(
     node,
   ),
 )
+const itWithoutExternalSkills = testEffect(
+  Layer.mergeAll(
+    Skill.layer.pipe(
+      Layer.provide(Discovery.defaultLayer),
+      Layer.provide(Config.defaultLayer),
+      Layer.provide(Bus.layer),
+      Layer.provide(AppFileSystem.defaultLayer),
+      Layer.provide(Global.layer),
+      Layer.provide(RuntimeFlags.layer({ disableExternalSkills: true })),
+    ),
+    node,
+  ),
+)
 
 async function createGlobalSkill(homeDir: string) {
   const skillDir = path.join(homeDir, ".claude", "skills", "global-test-skill")
@@ -420,6 +433,53 @@ description: A skill in the .agents/skills directory.
     ),
   )
 
+  itWithoutExternalSkills.live("skips external skill directories when disabled", () =>
+    provideTmpdirInstance(
+      (dir) =>
+        Effect.gen(function* () {
+          yield* Effect.promise(() =>
+            Promise.all([
+              Bun.write(
+                path.join(dir, ".claude", "skills", "claude-skill", "SKILL.md"),
+                `---
+name: claude-skill
+description: A skill in the .claude/skills directory.
+---
+
+# Claude Skill
+`,
+              ),
+              Bun.write(
+                path.join(dir, ".agents", "skills", "agent-skill", "SKILL.md"),
+                `---
+name: agent-skill
+description: A skill in the .agents/skills directory.
+---
+
+# Agent Skill
+`,
+              ),
+              Bun.write(
+                path.join(dir, ".opencode", "skill", "opencode-skill", "SKILL.md"),
+                `---
+name: opencode-skill
+description: A skill in the .opencode/skill directory.
+---
+
+# OpenCode Skill
+`,
+              ),
+            ]),
+          )
+
+          const skill = yield* Skill.Service
+          const list = (yield* skill.all()).filter((s) => s.location !== "<built-in>")
+          expect(list.map((s) => s.name)).toEqual(["opencode-skill"])
+        }),
+      { git: true },
+    ),
+  )
+
   it.live("properly resolves directories that skills live in", () =>
     provideTmpdirInstance(
       (dir) =>