fix(zoo-gateway): treat verify 5xx as transient, do not clear token

The website's /api/extension/auth/verify route now returns 503 when the
backend can't reach the database, instead of crashing. The extension
previously treated any non-OK response from this endpoint as a
definitively invalid token, which meant a transient backend hiccup
would silently clear the user's session and force a fresh sign-in.

verifyZooCodeToken now returns "unreachable" for 5xx responses (same
classification as a network error), so initZooCodeAuth keeps the cached
token in place and reports subscription status as "unknown" until the
backend recovers. handleAuthCallback shows the could-not-verify message
on 5xx so users see this is a temporary issue rather than a bad token.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: JamesRobert20

src/services/__tests__/zoo-code-auth.test.ts

@@ -242,6 +242,23 @@ describe("zoo-code-auth", () => {
 			expect(getCachedZooCodeUserInfo().name).toBe("Jane Doe")
 			expect(getCachedSubscriptionStatus()).toBe("unknown")
 		})
+
+		it("preserves token and user info when verify returns 5xx (transient backend error)", async () => {
+			await mockSecrets.store("zoo-code-session-token", "zoo_ext_valid_token")
+			await mockSecrets.store("zoo-code-user-name", "Jane Doe")
+			await mockSecrets.store("zoo-code-user-email", "jane@example.com")
+			mockFetch.mockResolvedValueOnce({
+				ok: false,
+				status: 503,
+				statusText: "Service Unavailable",
+			})
+
+			await initZooCodeAuth(mockContext)
+
+			expect(getCachedZooCodeToken()).toBe("zoo_ext_valid_token")
+			expect(getCachedZooCodeUserInfo().name).toBe("Jane Doe")
+			expect(getCachedSubscriptionStatus()).toBe("unknown")
+		})
 	})
 
 	describe("setZooCodeToken", () => {
@@ -365,7 +382,7 @@ describe("zoo-code-auth", () => {
 			expect(getCachedZooCodeToken()).toBe("zoo_ext_invalid_token")
 		})
 
-		it("returns 'invalid' when the backend returns HTTP error", async () => {
+		it("returns 'invalid' when the backend returns 4xx", async () => {
 			await initZooCodeAuth(mockContext)
 			await setZooCodeToken("zoo_ext_invalid_token")
 			mockFetch.mockResolvedValueOnce({
@@ -377,6 +394,19 @@ describe("zoo-code-auth", () => {
 			expect(await verifyZooCodeToken()).toBe("invalid")
 		})
 
+		it("returns 'unreachable' when the backend returns 5xx (transient)", async () => {
+			await initZooCodeAuth(mockContext)
+			await setZooCodeToken("zoo_ext_token")
+			mockFetch.mockResolvedValueOnce({
+				ok: false,
+				status: 503,
+				statusText: "Service Unavailable",
+			})
+
+			expect(await verifyZooCodeToken()).toBe("unreachable")
+			expect(getCachedZooCodeToken()).toBe("zoo_ext_token")
+		})
+
 		it("returns 'unreachable' when a network error occurs", async () => {
 			await initZooCodeAuth(mockContext)
 			await setZooCodeToken("zoo_ext_token")

src/services/zoo-code-auth.ts

@@ -245,7 +245,13 @@ export async function handleAuthCallback(token: string): Promise<boolean> {
 			signal: AbortSignal.timeout(10_000),
 		})
 		if (!response.ok) {
-			vscode.window.showErrorMessage(t("common:zooAuth.errors.token_verification_failed"))
+			// Treat 5xx as a transient backend issue (e.g. DB unreachable) so the
+			// user can retry sign-in instead of being told the token is bad.
+			if (response.status >= 500) {
+				vscode.window.showErrorMessage(t("common:zooAuth.errors.could_not_verify_token"))
+			} else {
+				vscode.window.showErrorMessage(t("common:zooAuth.errors.token_verification_failed"))
+			}
 			return false
 		}
 		const data = (await response.json()) as { valid?: boolean }
@@ -271,8 +277,12 @@ export async function handleAuthCallback(token: string): Promise<boolean> {
  * Verify the stored token against the backend.
  * Returns:
  *   - "valid"       — backend confirmed the token is good
- *   - "invalid"     — backend explicitly rejected the token (HTTP error or valid: false)
- *   - "unreachable" — network error / timeout; token state is unknown
+ *   - "invalid"     — backend explicitly rejected the token (4xx or valid: false)
+ *   - "unreachable" — network error / timeout / 5xx backend error; token state is unknown
+ *
+ * 5xx responses are treated as transient: the website returns 503 when the
+ * database is unreachable, and clearing a real session on a backend hiccup
+ * forces users to sign in again every time the API blips.
  *
  * This function has no side-effects; callers are responsible for acting on the result.
  */
@@ -289,6 +299,9 @@ export async function verifyZooCodeToken(): Promise<"valid" | "invalid" | "unrea
 		})
 
 		if (!response.ok) {
+			if (response.status >= 500) {
+				return "unreachable"
+			}
 			return "invalid"
 		}