Gateway: ack skipped hook transforms with 204

src/gateway/hooks-mapping.test.ts

@@ -74,6 +74,61 @@ describe("hooks mapping", () => {
     }
   });
 
+  it("treats null transform as a handled skip", async () => {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), "clawdis-hooks-skip-"));
+    const modPath = path.join(dir, "transform.mjs");
+    fs.writeFileSync(modPath, "export default () => null;");
+
+    const mappings = resolveHookMappings({
+      transformsDir: dir,
+      mappings: [
+        {
+          match: { path: "skip" },
+          action: "agent",
+          transform: { module: "transform.mjs" },
+        },
+      ],
+    });
+
+    const result = await applyHookMappings(mappings, {
+      payload: {},
+      headers: {},
+      url: new URL("http://127.0.0.1:18789/hooks/skip"),
+      path: "skip",
+    });
+
+    expect(result?.ok).toBe(true);
+    if (result?.ok) {
+      expect(result.action).toBeNull();
+      expect("skipped" in result).toBe(true);
+    }
+  });
+
+  it("prefers explicit mappings over presets", async () => {
+    const mappings = resolveHookMappings({
+      presets: ["gmail"],
+      mappings: [
+        {
+          id: "override",
+          match: { path: "gmail" },
+          action: "agent",
+          messageTemplate: "Override subject: {{messages[0].subject}}",
+        },
+      ],
+    });
+    const result = await applyHookMappings(mappings, {
+      payload: { messages: [{ subject: "Hello" }] },
+      headers: {},
+      url: baseUrl,
+      path: "gmail",
+    });
+    expect(result?.ok).toBe(true);
+    if (result?.ok) {
+      expect(result.action.kind).toBe("agent");
+      expect(result.action.message).toBe("Override subject: Hello");
+    }
+  });
+
   it("rejects missing message", async () => {
     const mappings = resolveHookMappings({
       mappings: [{ match: { path: "noop" }, action: "agent" }],

src/gateway/hooks-mapping.ts

@@ -70,6 +70,7 @@ export type HookAction =
 
 export type HookMappingResult =
   | { ok: true; action: HookAction }
+  | { ok: true; action: null; skipped: true }
   | { ok: false; error: string };
 
 const hookPresetMappings: Record<string, HookMappingConfig[]> = {
@@ -145,7 +146,9 @@ export async function applyHookMappings(
     if (mapping.transform) {
       const transform = await loadTransform(mapping.transform);
       override = await transform(ctx);
-      if (override === null) return null;
+      if (override === null) {
+        return { ok: true, action: null, skipped: true };
+      }
     }
 
     const merged = mergeAction(base.action, override, mapping.action);

src/gateway/server.ts

@@ -1706,6 +1706,11 @@ export async function startGatewayServer(
             sendJson(res, 400, { ok: false, error: mapped.error });
             return true;
           }
+          if (mapped.action === null) {
+            res.statusCode = 204;
+            res.end();
+            return true;
+          }
           if (mapped.action.kind === "wake") {
             dispatchWakeHook({
               text: mapped.action.text,