Fix z.ai BigModel CN quota parsing

CHANGELOG.md

@@ -16,6 +16,7 @@
 
 ### Fixed
 - Localization: translate the Default Terminal setting across every supported app language. Thanks @Zihao-Qi!
+- z.ai: parse successful BigModel CN quota responses that omit the optional message field, while preserving useful API-code errors. Thanks @joeVenner!
 - Claude: block background delegated CLI OAuth refresh when the keychain holds MCP-only state (`mcpOAuth` without `claudeAiOauth`) while preserving explicit Refresh recovery (#1844). Thanks @Yuxin-Qiao!
 
 ## 0.38.0 — 2026-07-03

Sources/CodexBarCore/Providers/Zai/ZaiUsageStats.swift

@@ -246,13 +246,19 @@ extension ZaiUsageSnapshot {
 /// Z.ai quota limit API response
 private struct ZaiQuotaLimitResponse: Decodable {
     let code: Int
-    let msg: String
+    let msg: String?
     let data: ZaiQuotaLimitData?
     let success: Bool
 
     var isSuccess: Bool {
         self.success && self.code == 200
     }
+
+    var errorMessage: String {
+        let message = self.msg?.trimmingCharacters(in: .whitespacesAndNewlines)
+        if let message, !message.isEmpty { return message }
+        return "Z.ai quota API returned code \(self.code)"
+    }
 }
 
 private struct ZaiQuotaLimitData: Decodable {
@@ -462,7 +468,7 @@ public struct ZaiUsageFetcher: Sendable {
         let apiResponse = try decoder.decode(ZaiQuotaLimitResponse.self, from: data)
 
         guard apiResponse.isSuccess else {
-            throw ZaiUsageError.apiError(apiResponse.msg)
+            throw ZaiUsageError.apiError(apiResponse.errorMessage)
         }
 
         guard let responseData = apiResponse.data else {

Tests/CodexBarTests/ZaiProviderTests.swift

@@ -310,6 +310,20 @@ struct ZaiUsageParsingTests {
         }
     }
 
+    @Test
+    func `failed response without message reports the API code`() {
+        let json = """
+        { "code": 1001, "success": false }
+        """
+
+        #expect {
+            _ = try ZaiUsageFetcher.parseUsageSnapshot(from: Data(json.utf8))
+        } throws: { error in
+            guard case let ZaiUsageError.apiError(message) = error else { return false }
+            return message == "Z.ai quota API returned code 1001"
+        }
+    }
+
     @Test
     func `success without data returns parse failed`() {
         let json = """
@@ -387,6 +401,57 @@ struct ZaiUsageParsingTests {
         #expect(snapshot.tokenLimit?.windowMinutes == 300)
         #expect(snapshot.timeLimit?.usage == 100)
     }
+
+    @Test
+    func `parses BigModel CN quota response without message`() throws {
+        let json = """
+        {
+          "code": 200,
+          "data": {
+            "limits": [
+              {
+                "type": "TIME_LIMIT",
+                "unit": 5,
+                "number": 1,
+                "usage": 1000,
+                "currentValue": 147,
+                "remaining": 853,
+                "percentage": 14,
+                "nextResetTime": 1784706344993,
+                "usageDetails": [
+                  { "modelCode": "search-prime", "usage": 84 },
+                  { "modelCode": "web-reader", "usage": 41 },
+                  { "modelCode": "zread", "usage": 8 }
+                ]
+              },
+              {
+                "type": "TOKENS_LIMIT",
+                "unit": 3,
+                "number": 5,
+                "percentage": 8,
+                "nextResetTime": 1783049703178
+              },
+              {
+                "type": "TOKENS_LIMIT",
+                "unit": 6,
+                "number": 1,
+                "percentage": 7,
+                "nextResetTime": 1783496744998
+              }
+            ],
+            "level": "pro"
+          },
+          "success": true
+        }
+        """
+
+        let snapshot = try ZaiUsageFetcher.parseUsageSnapshot(from: Data(json.utf8))
+        let usage = snapshot.toUsageSnapshot()
+
+        #expect(usage.primary?.usedPercent == 7)
+        #expect(usage.secondary?.usedPercent == 14.7)
+        #expect(usage.tertiary?.usedPercent == 8)
+    }
 }
 
 struct ZaiBigModelTeamScopeTests {