fix(syntax): reject bare apis-container bodies and cross-mode duplicate api names

Bare bodies inside apis {} silently discarded their text with no error,
producing a do-nothing block. They now throw a ParseError naming the entry
and pointing at the response {} section. Duplicate-name detection for
dataApis moved from an incremental, order-dependent check (only saw prior
entries in the array) to a single post-parse pass over the whole ast.dataApis,
so it catches cross-mode duplicates (apis {} vs ssr { api }) regardless of
declaration order.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

packages/syntax/src/api-sections.ts

@@ -172,8 +172,6 @@ export function hasRequestSection(source: string): boolean {
   return scanTopLevelBlocks(source, SECTION_NAMES).has("request");
 }
 
-const emptySections: ApiSections = { parameters: [], body: [], response: "", error: "" };
-
 /** Shape of an entry parsed from an `apis { }` container body. */
 export interface ApiEntry {
   mode: "any";
@@ -206,6 +204,12 @@ export function parseApiEntries(source: string): ApiEntry[] {
     }
     const path = lx.readPath();
     const entryBody = lx.readBalancedBraces();
+    const sections = parseApiSections(entryBody);
+    if (sections === null) {
+      throw new LexError(
+        `Api entry "${nameToken.value}" has a bare body; declare a "response { }" section instead`,
+      );
+    }
 
     entries.push({
       mode: "any",
@@ -213,7 +217,7 @@ export function parseApiEntries(source: string): ApiEntry[] {
       method: methodToken.value.toUpperCase(),
       path,
       body: "",
-      sections: parseApiSections(entryBody) ?? emptySections,
+      sections,
     });
   }
 

packages/syntax/src/parser.ts

@@ -853,12 +853,7 @@ export function parse(source: string): PageAst {
         case "apis": {
           lx.next();
           const body = lx.readBalancedBraces();
-          for (const entry of parseApiEntries(body)) {
-            if (dataApis.some((block) => block.name === entry.name)) {
-              throw new ParseError(`Duplicate api entry "${entry.name}" in apis block`);
-            }
-            dataApis.push(entry);
-          }
+          dataApis.push(...parseApiEntries(body));
           break;
         }
         default:
@@ -951,6 +946,15 @@ export function parse(source: string): PageAst {
       visited.add(name);
     };
     for (const name of namedLoads.keys()) visitLoad(name);
+
+    const seenApiNames = new Set<string>();
+    for (const block of dataApis) {
+      if (seenApiNames.has(block.name)) {
+        throw new ParseError(`Duplicate api entry "${block.name}"`, "WRN-API-DUPLICATE");
+      }
+      seenApiNames.add(block.name);
+    }
+
     return {
       type: "page",
       imports,

packages/syntax/test/apis-block.test.ts

@@ -69,3 +69,47 @@ test("duplicate names inside one container are rejected", () => {
     ),
   ).toThrow(/duplicate/i);
 });
+
+test("a bare body inside apis {} is a parse error naming response", () => {
+  expect(() => parse(page(`    bare GET /api/z { return data }`))).toThrow(/response/i);
+});
+
+test("apis entry followed by an ssr api of the same name is rejected", () => {
+  const src = `page Repro {
+  apis {
+    foo GET /api/foo { response { return data } }
+  }
+
+  ssr {
+    api foo GET /api/foo { return data }
+  }
+
+  view { <main>x</main> }
+}
+`;
+  expect(() => parse(src)).toThrow(/duplicate/i);
+});
+
+test("ssr api followed by an apis entry of the same name is rejected", () => {
+  const src = `page Repro {
+  ssr {
+    api foo GET /api/foo { return data }
+  }
+
+  apis {
+    foo GET /api/foo { response { return data } }
+  }
+
+  view { <main>x</main> }
+}
+`;
+  expect(() => parse(src)).toThrow(/duplicate/i);
+});
+
+test("an explicit empty response section is accepted, unlike a bare body", () => {
+  const ast = parse(page(`    empty GET /api/e { response { } }`));
+
+  const block = ast.dataApis[0]!;
+  expect(block.name).toBe("empty");
+  expect(block.sections?.response.trim()).toBe("");
+});