fix(marketplace): close client contract gaps

tests/unit/coding-plugin-marketplace-contract.test.ts

@@ -121,6 +121,16 @@ describe('Marketplace Release A package contract', () => {
     expect(Object.isFrozen(definition.tools[0]?.outputSchema)).toBe(true);
   });
 
+  it('accepts only the canonical asynchronous job execution mode', () => {
+    const job = structuredClone(HOSTED_CAPABILITY) as Record<string, unknown>;
+    (job.tools as Array<Record<string, unknown>>)[0]!.executionMode = 'job';
+    expect(parse(job).tools[0]?.executionMode).toBe('job');
+
+    const accepted = structuredClone(HOSTED_CAPABILITY) as Record<string, unknown>;
+    (accepted.tools as Array<Record<string, unknown>>)[0]!.executionMode = 'accepted';
+    expect(() => parse(accepted)).toThrow(CodingPluginManifestError);
+  });
+
   it('requires the exact capability manifest path even for direct parsing', () => {
     const root = structuredClone(ROOT) as Record<string, unknown>;
     const extensions = root.extensions as Record<string, unknown>;