diff --git a/changelog.d/fixes/8860-tokenrefresh-projectid.md b/changelog.d/fixes/8860-tokenrefresh-projectid.md
new file mode 100644
index 0000000000..3a091523cb
--- /dev/null
+++ b/changelog.d/fixes/8860-tokenrefresh-projectid.md
@@ -0,0 +1 @@
+- **Antigravity**: the shared token-refresh service now recovers a missing `projectId` too — #8842 fixed the executor path, but the Dashboard and the health check refresh through `open-sse/services/tokenRefresh.ts`, which kept returning credentials with an empty project and left those accounts on 422
diff --git a/config/quality/file-size-baseline.json b/config/quality/file-size-baseline.json
index 5acc9b8e5d..64f5b58f42 100644
--- a/config/quality/file-size-baseline.json
+++ b/config/quality/file-size-baseline.json
@@ -197,7 +197,7 @@
     "tests/unit/search-handler-extended.test.ts": 1071,
     "tests/unit/sse-auth.test.ts": 1600,
     "tests/unit/stream-utils.test.ts": 2445,
-    "tests/unit/token-refresh-service.test.ts": 1311,
+    "tests/unit/token-refresh-service.test.ts": 1378,
     "tests/unit/translator-openai-responses-req.test.ts": 1194,
     "tests/unit/translator-openai-to-gemini.test.ts": 1616,
     "tests/unit/translator-openai-to-kiro.test.ts": 1250,
@@ -409,5 +409,6 @@
   "_rebaseline_2026_07_27_v3849_train2": "Merge-train 2 (7 PRs) — owner-approved 2026-07-27. Single entry: chatCore.ts 4955->5006 (#8595, Responses multi-turn image compaction before the context hard-reject). Genuine irreducible growth at the existing compaction chokepoint in handleChatCore — the PR adds a last-resort retry against the concrete budget plus the estimateFinalInputTokens helper, both wired at the pre-existing call site rather than a new branch. Covered by tests/unit/8560-responses-image-compaction.test.ts (4 tests).",
   "_rebaseline_2026_07_27_v3849_train3": "Merge-train 3 (13 PRs) — owner-approved 2026-07-27. Both entries are genuine irreducible growth at existing chokepoints, not new branches: src/lib/db/apiKeys.ts 1518->1529 (#8805 cx/* ≡ codex/* API-key model permissions); open-sse/handlers/chatCore.ts 5006->5020 (#8806 real response payload into plugin onResponse hooks). Covered by tests/unit/db-apiKeys-crud.test.ts (4 new cases) and the two plugin-hook test files updated in #8806 respectively.",
   "_rebaseline_2026_07_28_8842_antigravity_projectid_refresh": "PR #8842 (fix/antigravity-projectid-refresh) own growth: open-sse/executors/antigravity.ts 1493->1528 (+35 = projectId discovery in refreshCredentials: import ensureAntigravityProjectAssigned + trim projectId + call ensureAntigravityProjectAssigned with 8s timeout + persistDiscoveredAntigravityProjectId + log success/failure). Irreducible wiring at the existing credential-refresh chokepoint. Covered by tests/unit/executor-antigravity.test.ts (4 new test cases).",
-  "_rebaseline_2026_07_28_8842_antigravity_test": "PR #8842 test growth: tests/unit/executor-antigravity.test.ts new testFrozen 1098 (4 new test cases for projectId discovery during refresh: discovers when empty, skips when set, handles failure, skips when access_token not a string). All above cap 1000 on day one."
+  "_rebaseline_2026_07_28_8842_antigravity_test": "PR #8842 test growth: tests/unit/executor-antigravity.test.ts new testFrozen 1098 (4 new test cases for projectId discovery during refresh: discovers when empty, skips when set, handles failure, skips when access_token not a string). All above cap 1000 on day one.",
+  "_rebaseline_2026_07_28_8860_tokenrefresh_projectid": "PR #8860 (fix/antigravity-projectid-centralized) own test growth: tests/unit/token-refresh-service.test.ts 1311->1378 (+67 = 4 cases covering projectId discovery on the tokenRefresh.ts path — the Dashboard/health-check refresh route, which #8842 did not reach since that fixed the executor path). Covered by the same file."
 }
diff --git a/open-sse/services/tokenRefresh.ts b/open-sse/services/tokenRefresh.ts
index 13c9e23677..b4a6e2afe7 100755
--- a/open-sse/services/tokenRefresh.ts
+++ b/open-sse/services/tokenRefresh.ts
@@ -45,6 +45,8 @@ import { refreshKimiCodingToken } from "./tokenRefresh/providers/kimiCoding.ts";
 import { refreshGitLabDuoToken } from "./tokenRefresh/providers/gitlabDuo.ts";
 import { refreshClaudeOAuthToken } from "./tokenRefresh/providers/claudeOAuth.ts";
 import { refreshGoogleToken } from "./tokenRefresh/providers/google.ts";
+import { ensureAntigravityProjectAssigned } from "./antigravityProjectBootstrap.ts";
+import { persistDiscoveredAntigravityProjectId } from "./antigravityProjectPersist.ts";
 import { refreshCodexToken } from "./tokenRefresh/providers/codex.ts";
 import { refreshKiroToken } from "./tokenRefresh/providers/kiro.ts";
 import { refreshQoderToken } from "./tokenRefresh/providers/qoder.ts";
@@ -275,8 +277,8 @@ async function _getAccessTokenInternal(provider, credentials, log, proxyConfig:
 
     case "gemini":
     case "antigravity":
-    case "agy":
-      return await refreshGoogleToken(
+    case "agy": {
+      const result = await refreshGoogleToken(
         credentials.refreshToken,
         PROVIDERS[provider].clientId,
         PROVIDERS[provider].clientSecret,
@@ -284,6 +286,45 @@ async function _getAccessTokenInternal(provider, credentials, log, proxyConfig:
         proxyConfig
       );
 
+      // Google One AI accounts get no projectId at OAuth exchange time.
+      // Recover it via loadCodeAssist so downstream routing works.
+      if (
+        result?.accessToken &&
+        (provider === "antigravity" || provider === "agy") &&
+        !(credentials.projectId || credentials.providerSpecificData?.projectId)
+      ) {
+        try {
+          const discovered = await ensureAntigravityProjectAssigned(
+            result.accessToken,
+            fetch
+          );
+          if (discovered) {
+            result.projectId = discovered;
+            result.providerSpecificData = {
+              ...(credentials.providerSpecificData || {}),
+              ...(result.providerSpecificData || {}),
+              projectId: discovered,
+            };
+            if (credentials.connectionId) {
+              await persistDiscoveredAntigravityProjectId(
+                credentials.connectionId,
+                discovered,
+                credentials.providerSpecificData
+              );
+            }
+            log?.info?.("TOKEN", "Antigravity projectId discovered during token refresh", {
+              projectId: discovered,
+            });
+          }
+        } catch (discoveryError) {
+          const msg = discoveryError instanceof Error ? discoveryError.message : String(discoveryError);
+          log?.warn?.("TOKEN", `Antigravity projectId discovery failed: ${msg}`);
+        }
+      }
+
+      return result;
+    }
+
     case "claude":
       return await refreshClaudeOAuthToken(credentials.refreshToken, log, proxyConfig);
 
diff --git a/tests/unit/token-refresh-service.test.ts b/tests/unit/token-refresh-service.test.ts
index eb75adb0d3..fdc7ef16c0 100644
--- a/tests/unit/token-refresh-service.test.ts
+++ b/tests/unit/token-refresh-service.test.ts
@@ -795,6 +795,73 @@ test("supportsTokenRefresh, isUnrecoverableRefreshError and formatProviderCreden
   assert.equal(formatProviderCredentials("missing-provider", {}, log), null);
 });
 
+test("getAccessToken discovers projectId for antigravity when stored value is empty", async () => {
+  const log = createLog();
+  const { clearAntigravityProjectCache } = await import("../../open-sse/services/antigravityProjectBootstrap.ts");
+  clearAntigravityProjectCache();
+
+  let fetchCalls: string[] = [];
+  await withMockedFetch(async (url, init) => {
+    const urlStr = String(url);
+    fetchCalls.push(urlStr);
+    if (urlStr.includes("oauth2.googleapis.com/token")) {
+      return jsonResponse({
+        access_token: "new-token-1",
+        refresh_token: "new-refresh",
+        expires_in: 3600,
+      });
+    }
+    if (urlStr.includes("loadCodeAssist")) {
+      return jsonResponse({ cloudaicompanionProject: "discovered-project" });
+    }
+    return new Response("not found", { status: 404 });
+  }, async () => {
+    const result = await getAccessToken("antigravity", {
+      refreshToken: "refresh",
+      projectId: "",
+      connectionId: "conn-1",
+      providerSpecificData: {},
+    });
+    assert.equal(result.projectId, "discovered-project");
+    assert.ok(fetchCalls.some((u) => u.includes("loadCodeAssist")), "should call loadCodeAssist");
+  });
+  clearAntigravityProjectCache();
+});
+
+
+test("getAccessToken handles projectId discovery failure gracefully for antigravity", async () => {
+  const log = createLog();
+  const { clearAntigravityProjectCache } = await import("../../open-sse/services/antigravityProjectBootstrap.ts");
+  clearAntigravityProjectCache();
+  tokenRefresh._clearTokenRotationMap();
+
+  await withMockedFetch(async (url) => {
+    const urlStr = String(url);
+    if (urlStr.includes("oauth2.googleapis.com/token")) {
+      return jsonResponse({
+        access_token: "new-token-3",
+        refresh_token: "new-refresh",
+        expires_in: 3600,
+      });
+    }
+    if (urlStr.includes("loadCodeAssist")) {
+      return new Response("server error", { status: 500 });
+    }
+    return new Response("not found", { status: 404 });
+  }, async () => {
+    const result = await getAccessToken("antigravity", {
+      refreshToken: "refresh",
+      projectId: "",
+      connectionId: "conn-1",
+      providerSpecificData: {},
+    });
+    assert.equal(result.accessToken, "new-token-3");
+    assert.ok(result, "should return a result without throwing");
+  });
+  clearAntigravityProjectCache();
+});
+
+
 test("getAccessToken deduplicates concurrent refreshes for the same provider and token", async () => {
   const log = createLog();
   let fetchCount = 0;