Close endpoint failure types across service and web boundaries

web/test/mutations.test.mjs

@@ -51,7 +51,7 @@ test('partial delete recovery preserves only unfinished identities', () => {
         path: 'uncertain',
         operation_id: 'uncertain-id',
         result: null,
-        error: 'transport interrupted'
+        error: 'object_store_unavailable'
       }
     ],
     () => ids.shift()

web/test/transport.test.mjs

@@ -132,6 +132,43 @@ test('shared fixtures decode through every JSON transport method', async () => {
   );
 });
 
+test('delete batch decoding enforces the typed item outcome', async () => {
+  const failureClient = new BrowserProductClient(async () =>
+    jsonResponse({
+      results: [
+        {
+          path: 'folder/file.txt',
+          operation_id: 'operation-1',
+          result: null,
+          error: 'database_unavailable'
+        }
+      ]
+    })
+  );
+  const failure = requireValue(
+    await failureClient.deleteBatch({ body: fixtures.delete_batch_request })
+  );
+  assert.equal(failure.results[0].error, 'database_unavailable');
+
+  const invalidClient = new BrowserProductClient(async () =>
+    jsonResponse({
+      results: [
+        {
+          path: 'folder/file.txt',
+          operation_id: 'operation-1',
+          result: 'succeeded',
+          error: 'object_store_unavailable'
+        }
+      ]
+    })
+  );
+  const invalid = await invalidClient.deleteBatch({
+    body: fixtures.delete_batch_request
+  });
+  assert.equal(invalid.ok, false);
+  assert.equal(invalid.failure.kind, 'unexpected-http');
+});
+
 test('declared, undeclared, and network failures remain distinct without retries', async () => {
   const declaredClient = new BrowserProductClient(async () =>
     jsonResponse(