fix(skill-memory): reject ctx_skill_note when skill-memory is disabled in frontmatter

Counterpart to ctx_skill_recall's enabled-guard (greptile review, PR cortexkit#181):
without it, notes for skills that never opted in inserted successfully but
were permanently orphaned — recallSkillMemoryBlock returns "" when
frontmatter is disabled, while the agent saw a convincing 'Skill note
saved' response. Now returns an actionable error before any insert.

Red-checked: new regression test fails without the guard (orphan row
inserted + 'saved' response), passes with it (no row, 'not enabled').

Author: Tehan

packages/plugin/src/tools/ctx-skill-note/tools.test.ts

@@ -69,6 +69,43 @@ describe("ctx_skill_note tool", () => {
         }
     });
 
+    test("rejects note when skill-memory is disabled in frontmatter (no orphan insert)", async () => {
+        const db = makeDb();
+        const registry: SkillLoadRegistry = createSkillLoadRegistry();
+        try {
+            // Registry entry WITHOUT skill-memory opt-in (frontmatterConfig null —
+            // the shape the after-hook stores for skills that never enabled it).
+            registry.set(registryKey("ses_test", "tdd"), {
+                resolvedPath: "/home/user/.config/opencode/skills/tdd/SKILL.md",
+                tier: "global",
+                skillSource: "opencode-global",
+                skillId: "tdd",
+                loadedAt: Date.now(),
+                frontmatterConfig: null,
+            });
+
+            const t = createCtxSkillNoteTool({ db, skillLoadRegistry: registry });
+            const result = await t.execute(
+                {
+                    skill: "tdd",
+                    intent: "fix flaky test",
+                    kind: "gotcha",
+                    delta: "Always mock the clock",
+                },
+                toolContext(),
+            );
+            expect(result).toContain("not enabled");
+            expect(result).not.toContain("saved");
+            // No orphaned row inserted
+            const row = db
+                .prepare("SELECT COUNT(*) AS n FROM skill_memory WHERE skill_id = 'tdd'")
+                .get() as { n: number };
+            expect(row.n).toBe(0);
+        } finally {
+            closeQuietly(db);
+        }
+    });
+
     test("inserts note when skill is in registry", async () => {
         const db = makeDb();
         const registry: SkillLoadRegistry = createSkillLoadRegistry();

packages/plugin/src/tools/ctx-skill-note/tools.ts

@@ -85,6 +85,17 @@ export function createCtxSkillNoteTool(deps: CtxSkillNoteToolDeps): ToolDefiniti
                 );
             }
 
+            // Counterpart to ctx_skill_recall's enabled-guard: without it, notes for
+            // skills that never opted in would insert successfully but be permanently
+            // orphaned (recallSkillMemoryBlock returns "" when frontmatter is disabled),
+            // while the agent sees a convincing "Skill note saved" response.
+            if (!registryEntry.frontmatterConfig?.enabled) {
+                return (
+                    `skill-memory is not enabled for '${args.skill}', so this note would never be surfaced. ` +
+                    `To enable it, add \`skill-memory: { enabled: true }\` to the skill's SKILL.md frontmatter, reload the skill, then record the note.`
+                );
+            }
+
             // Use toolContext.directory (the session's working directory) rather than
             // a launch dir. This matches ctx_memory's pattern and correctly handles
             // `opencode -s` launched outside the project root.