fix(mongodb): label sampled date and ObjectId fields with BSON types

apps/desktop/src/lib/mongo/mongoCompletion.ts

@@ -2331,10 +2331,13 @@ function collectFieldTypes(value: unknown, prefix: string, out: Map<string, Set<
   }
 }
 
+const LEGACY_ISODATE_PATTERN = /^ISODate\("[^"]*"\)$/;
+
 function describeMongoValueType(value: unknown): string {
   if (value == null) return "null";
   if (Array.isArray(value)) return "array";
   if (value instanceof Date) return "date";
+  if (typeof value === "string" && LEGACY_ISODATE_PATTERN.test(value)) return "date";
   return mongoExtendedJsonValueType(value) ?? (typeof value === "object" ? "object" : typeof value);
 }
 

apps/desktop/src/stores/__tests__/connectionStore.mongoCompletionFields.spec.ts

@@ -102,4 +102,78 @@ describe("connectionStore listMongoCompletionFields", () => {
     expect(cached).toEqual(fields);
     expect(api.mongoFindDocuments).toHaveBeenCalledOnce();
   });
+
+  it("infers types from extended_documents when returned by mongoAggregateDocuments", async () => {
+    const api = {
+      mongoAggregateDocuments: vi.fn().mockResolvedValue({
+        documents: [{ _id: "65f0c0ffee00000000000001", createdAt: "2026-01-01T00:00:00Z", ref: "65f0c0ffee0000000000abcd" }],
+        extended_documents: [{ _id: { $oid: "65f0c0ffee00000000000001" }, createdAt: { $date: "2026-01-01T00:00:00Z" }, ref: { $oid: "65f0c0ffee0000000000abcd" } }],
+      }),
+      mongoFindDocuments: vi.fn(),
+    };
+    vi.doMock("@/lib/backend/tauriRuntime", () => ({ isTauriRuntime: () => false }));
+    vi.doMock("@/lib/backend/api", () => api);
+
+    const { useConnectionStore } = await import("@/stores/connectionStore");
+    const store = useConnectionStore();
+    const config = mongoConnection();
+    store.addEphemeralConnection(config);
+
+    const fields = await store.listMongoCompletionFields(config.id, "app", "users");
+
+    expect(fields).toEqual([
+      { name: "_id", type: "objectId" },
+      { name: "createdAt", type: "date" },
+      { name: "ref", type: "objectId" },
+    ]);
+  });
+
+  it("infers types from extended_documents when returned by mongoFindDocuments fallback", async () => {
+    const api = {
+      mongoAggregateDocuments: vi.fn().mockRejectedValue(new Error("Aggregation not supported")),
+      mongoFindDocuments: vi.fn().mockResolvedValue({
+        documents: [{ _id: "65f0c0ffee00000000000001", createdAt: "2026-01-01T00:00:00Z", ref: "65f0c0ffee0000000000abcd" }],
+        extended_documents: [{ _id: { $oid: "65f0c0ffee00000000000001" }, createdAt: { $date: "2026-01-01T00:00:00Z" }, ref: { $oid: "65f0c0ffee0000000000abcd" } }],
+      }),
+    };
+    vi.doMock("@/lib/backend/tauriRuntime", () => ({ isTauriRuntime: () => false }));
+    vi.doMock("@/lib/backend/api", () => api);
+
+    const { useConnectionStore } = await import("@/stores/connectionStore");
+    const store = useConnectionStore();
+    const config = mongoConnection();
+    store.addEphemeralConnection(config);
+
+    const fields = await store.listMongoCompletionFields(config.id, "app", "users");
+
+    expect(fields).toEqual([
+      { name: "_id", type: "objectId" },
+      { name: "createdAt", type: "date" },
+      { name: "ref", type: "objectId" },
+    ]);
+  });
+
+  it("falls back to documents when extended_documents is absent or length mismatches", async () => {
+    const api = {
+      mongoAggregateDocuments: vi.fn().mockResolvedValue({
+        documents: [{ _id: "1", fallbackField: "val" }],
+        extended_documents: [],
+      }),
+      mongoFindDocuments: vi.fn(),
+    };
+    vi.doMock("@/lib/backend/tauriRuntime", () => ({ isTauriRuntime: () => false }));
+    vi.doMock("@/lib/backend/api", () => api);
+
+    const { useConnectionStore } = await import("@/stores/connectionStore");
+    const store = useConnectionStore();
+    const config = mongoConnection();
+    store.addEphemeralConnection(config);
+
+    const fields = await store.listMongoCompletionFields(config.id, "app", "users");
+
+    expect(fields).toEqual([
+      { name: "_id", type: "string" },
+      { name: "fallbackField", type: "string" },
+    ]);
+  });
 });

apps/desktop/src/stores/connectionStore.ts

@@ -8817,7 +8817,8 @@ export const useConnectionStore = defineStore("connection", () => {
       } catch {
         result = await api.mongoFindDocuments(connectionId, database, collection, 0, 100, "{}");
       }
-      const fields = inferMongoCompletionFields(result.documents ?? []);
+      const sampled = result.extended_documents?.length === result.documents.length ? result.extended_documents : result.documents;
+      const fields = inferMongoCompletionFields(sampled ?? []);
       mongoCompletionFieldsCache.value[cacheKey] = fields;
       evictOldestCacheEntries(mongoCompletionFieldsCache.value, COMPLETION_CACHE_MAX);
       return fields;

packages/app-tests/mongoCompletion.test.ts

@@ -1779,6 +1779,35 @@ test("treats extended JSON wrappers as scalars, not subdocuments", () => {
   assert.ok(inferred.find((field) => field.name === "profile.email" && field.type === "string"));
 });
 
+test("infers BSON types from extended JSON values and legacy ISODate strings", () => {
+  const inferred = inferMongoCompletionFields([
+    {
+      createdAt: { $date: "2026-01-01T00:00:00Z" },
+      ref: { $oid: "65f0c0ffee0000000000abcd" },
+      price: { $numberDecimal: "1.5" },
+    },
+  ]);
+
+  for (const phantom of ["createdAt.$date", "ref.$oid", "price.$numberDecimal"]) {
+    assert.equal(
+      inferred.some((field) => field.name === phantom),
+      false,
+      phantom,
+    );
+  }
+
+  assert.equal(inferred.find((field) => field.name === "createdAt")?.type, "date");
+  assert.equal(inferred.find((field) => field.name === "ref")?.type, "objectId");
+  assert.equal(inferred.find((field) => field.name === "price")?.type, "decimal128");
+
+  const legacyInferred = inferMongoCompletionFields([
+    {
+      createdAt: 'ISODate("2026-01-01T00:00:00Z")',
+    },
+  ]);
+  assert.equal(legacyInferred.find((field) => field.name === "createdAt")?.type, "date");
+});
+
 test("infers dotted MongoDB fields from sampled documents", () => {
   const inferred = inferMongoCompletionFields([
     { _id: "1", profile: { email: "a@example.com" }, tags: ["a"] },