fix(type-generator): treat empty/un-rendered definitions.json as no metric views

packages/appkit/src/type-generator/mv-registry/config.ts

@@ -46,11 +46,17 @@ function compareKeys(a: string, b: string): number {
  * Read {@link METRIC_CONFIG_FILE} from a metric-views folder
  * (`config/metric-views/`).
  *
- * Returns `null` if the file does not exist (the metric-view path is
- * additive — apps without definitions.json must not be penalized). There is
- * deliberately no fallback to a legacy filename.
+ * Returns `null` if the file does not exist, is empty, or has not been rendered
+ * yet (the metric-view path is additive — apps without a defined
+ * definitions.json must not be penalized). The template ships definitions.json
+ * wrapped in a `{{if .plugins.analytics}}` guard, so scaffolding without the
+ * analytics plugin leaves the file empty, and running typegen against the raw
+ * (un-rendered) template leaves the literal `{{...}}` in place — neither is a
+ * misconfiguration, so both are treated the same as an absent file rather than
+ * a fatal parse error. There is deliberately no fallback to a legacy filename.
  *
- * Throws on JSON parse errors so misconfiguration surfaces loudly.
+ * Throws on JSON parse errors in a *non-empty, rendered* file so genuine
+ * misconfiguration still surfaces loudly.
  */
 export async function readMetricConfig(
   metricViewsFolder: string,
@@ -66,6 +72,14 @@ export async function readMetricConfig(
     throw err;
   }
 
+  // An empty file (analytics plugin off → the `{{if}}` guard renders nothing)
+  // or an un-rendered template (raw `{{...}}` left in place during typegen on
+  // the template itself) means "no metric views" — treat like an absent file.
+  const trimmed = raw.trim();
+  if (trimmed === "" || trimmed.startsWith("{{")) {
+    return null;
+  }
+
   let parsed: unknown;
   try {
     parsed = JSON.parse(raw);

packages/appkit/src/type-generator/tests/mv-registry.test.ts

@@ -94,6 +94,29 @@ describe("readMetricConfig", () => {
     expect(await readMetricConfig(tmpDir)).toBeNull();
   });
 
+  test("returns null for an empty definitions.json (analytics plugin off)", async () => {
+    // The template wraps definitions.json in `{{if .plugins.analytics}}`, so
+    // scaffolding without the analytics plugin renders an empty file. That's
+    // "no metric views", not a parse error.
+    await fs.writeFile(path.join(tmpDir, "definitions.json"), "");
+    expect(await readMetricConfig(tmpDir)).toBeNull();
+  });
+
+  test("returns null for a whitespace-only definitions.json", async () => {
+    await fs.writeFile(path.join(tmpDir, "definitions.json"), "\n  \n");
+    expect(await readMetricConfig(tmpDir)).toBeNull();
+  });
+
+  test("returns null for an un-rendered template definitions.json", async () => {
+    // Running typegen against the raw template (e.g. npm-install warmup before
+    // `appkit setup`) leaves the Go-template guard literal in place.
+    await fs.writeFile(
+      path.join(tmpDir, "definitions.json"),
+      '{{if .plugins.analytics -}}\n{ "metricViews": {} }\n{{- end}}\n',
+    );
+    expect(await readMetricConfig(tmpDir)).toBeNull();
+  });
+
   test("parses a valid definitions.json", async () => {
     await fs.writeFile(
       path.join(tmpDir, "definitions.json"),