diff --git a/src/oauth/account-import/google-antigravity-adapter.ts b/src/oauth/account-import/google-antigravity-adapter.ts
index 4c62e4c022e..b40d2a49c7e 100644
--- a/src/oauth/account-import/google-antigravity-adapter.ts
+++ b/src/oauth/account-import/google-antigravity-adapter.ts
@@ -52,7 +52,11 @@ export function createAntigravityAccountImportAdapter(
       const providerEmail = safeProviderEmail(credential.email);
       if (!providerEmail) return { status: "failed", code: "credential_rejected" };
       if (providerEmail !== record.email) return { status: "failed", code: "identity_mismatch" };
-      if (typeof credential.projectId !== "string" || credential.projectId.length === 0) {
+      // Automatic discovery takes precedence; record.projectId serves as operator-supplied fallback
+      const resolvedProjectId = (typeof credential.projectId === "string" && credential.projectId.length > 0)
+        ? credential.projectId
+        : record.projectId;
+      if (typeof resolvedProjectId !== "string" || resolvedProjectId.length === 0) {
         return { status: "failed", code: "missing_project" };
       }
 
@@ -61,6 +65,7 @@ export function createAntigravityAccountImportAdapter(
         const disposition = await deps.upsert({
           ...credential,
           email: providerEmail,
+          projectId: resolvedProjectId,
           source: "credential-file",
         });
         return disposition === "updated"
diff --git a/src/oauth/account-import/parser.ts b/src/oauth/account-import/parser.ts
index 7023ab79f4d..f69c21330b6 100644
--- a/src/oauth/account-import/parser.ts
+++ b/src/oauth/account-import/parser.ts
@@ -1,13 +1,14 @@
 import {
   ACCOUNT_IMPORT_MAX_BYTES,
   ACCOUNT_IMPORT_MAX_EMAIL_LENGTH,
+  ACCOUNT_IMPORT_MAX_PROJECT_ID_LENGTH,
   ACCOUNT_IMPORT_MAX_RECORDS,
   ACCOUNT_IMPORT_MAX_REFRESH_TOKEN_BYTES,
   type ParsedCockpitRecord,
 } from "./types";
 
 const encoder = new TextEncoder();
-const ALLOWED_RECORD_KEYS = new Set(["email", "refresh_token", "tags", "notes"]);
+const ALLOWED_RECORD_KEYS = new Set(["email", "refresh_token", "project_id", "tags", "notes"]);
 
 export type CockpitDocumentParseResult =
   | { ok: true; records: ParsedCockpitRecord[] }
@@ -50,17 +51,27 @@ function validMetadata(record: Record<string, unknown>): boolean {
   return record.notes === undefined || typeof record.notes === "string";
 }
 
+function validProjectId(value: unknown): value is string | undefined {
+  if (value === undefined) return true;
+  if (typeof value !== "string") return false;
+  const trimmed = value.trim();
+  if (trimmed.length === 0 || trimmed.length > ACCOUNT_IMPORT_MAX_PROJECT_ID_LENGTH) return false;
+  return /^[a-z0-9][a-z0-9_.-]*[a-z0-9]$/i.test(trimmed);
+}
+
 function parseRecord(value: unknown, index: number): ParsedCockpitRecord {
   if (!isPlainRecord(value)) return { index, code: "invalid_record" };
   if (Object.keys(value).some(key => !ALLOWED_RECORD_KEYS.has(key))) return { index, code: "invalid_record" };
-  if (!validEmail(value.email) || !validRefreshToken(value.refresh_token) || !validMetadata(value)) {
+  if (!validEmail(value.email) || !validRefreshToken(value.refresh_token) || !validProjectId(value.project_id) || !validMetadata(value)) {
     return { index, code: "invalid_record" };
   }
+  const projectId = typeof value.project_id === "string" ? value.project_id.trim() : undefined;
   return {
     index,
     record: {
       email: value.email.toLowerCase(),
       refreshToken: value.refresh_token,
+      ...(projectId ? { projectId } : {}),
     },
   };
 }
diff --git a/src/oauth/account-import/types.ts b/src/oauth/account-import/types.ts
index 5330bd5bb62..ce88bcab160 100644
--- a/src/oauth/account-import/types.ts
+++ b/src/oauth/account-import/types.ts
@@ -11,6 +11,7 @@ export const ACCOUNT_IMPORT_MAX_REQUEST_BYTES = ACCOUNT_IMPORT_MAX_BYTES + 1024;
 export const ACCOUNT_IMPORT_DEADLINE_MS = 600_000;
 export const ACCOUNT_IMPORT_MAX_RECORDS = 25;
 export const ACCOUNT_IMPORT_MAX_EMAIL_LENGTH = 254;
+export const ACCOUNT_IMPORT_MAX_PROJECT_ID_LENGTH = 64;
 export const ACCOUNT_IMPORT_MAX_REFRESH_TOKEN_BYTES = 16 * 1024;
 
 export type AccountImportStatus = "imported" | "updated" | "failed" | "unsupported";
@@ -65,6 +66,7 @@ export function throwIfAccountImportAborted(signal?: AbortSignal): void {
 export interface CockpitAccountRecord {
   email: string;
   refreshToken: string;
+  projectId?: string;
 }
 
 export type ParsedCockpitRecord =
diff --git a/tests/server/account-import.test.ts b/tests/server/account-import.test.ts
index 51732607396..10797d3f326 100644
--- a/tests/server/account-import.test.ts
+++ b/tests/server/account-import.test.ts
@@ -55,6 +55,11 @@ describe("Cockpit account-import parser", () => {
       record({ email: `${"a".repeat(250)}@x.io` }),
       record({ refresh_token: "token\ncontrol" }),
       record({ refresh_token: "x".repeat(16 * 1024 + 1) }),
+      record({ project_id: "" }),
+      record({ project_id: 123 }),
+      record({ project_id: "invalid project with spaces" }),
+      record({ project_id: "-leading-hyphen" }),
+      record({ project_id: "x".repeat(65) }),
       "not-an-object",
     ]);
     expect(parsed.ok).toBe(true);
@@ -87,6 +92,39 @@ describe("Cockpit account-import service and adapter", () => {
       .toEqual({ ok: false, status: 400, code: "unsupported_format" });
   });
 
+  test("propagates optional project_id from document through importAccounts to persistence when discovery yields none", async () => {
+    let capturedCredential: any = null;
+    const adapter = createAntigravityAccountImportAdapter({
+      validate: async () => ({
+        access: "access-valid",
+        refresh: "refresh-valid",
+        expires: Date.now() + 60_000,
+        email: "fallback@example.com",
+        projectId: undefined,
+      }),
+      upsert: async (cred) => {
+        capturedCredential = cred;
+        return "inserted";
+      },
+    });
+
+    const result = await importAccounts({
+      provider: ACCOUNT_IMPORT_PROVIDER,
+      format: ACCOUNT_IMPORT_FORMAT,
+      document: [
+        record({ email: "fallback@example.com", refresh_token: "refresh-valid", project_id: "aicode-consumers" }),
+      ],
+    }, { resolveAdapter: () => ({ ok: true, adapter }) });
+
+    expect(result.ok).toBe(true);
+    if (result.ok) {
+      expect(result.result.importedCount).toBe(1);
+      expect(result.result.failedCount).toBe(0);
+    }
+    expect(capturedCredential).not.toBeNull();
+    expect(capturedCredential?.projectId).toBe("aicode-consumers");
+  });
+
   test("processes valid records sequentially and exposes only fixed result fields", async () => {
     let active = 0;
     let highWater = 0;