fix(agent-subscriptions): handle MiniMax API v2 response shape

MiniMax changed from category_remains[text_generation] with count fields
to model_remains[general] with remaining_percent fields. Now tries v2
first (100 - remaining_percent), falls back to v1 count-based calculation.

scripts/agent-subscriptions

@@ -116,7 +116,12 @@ def probe_anthropic(token: str) -> dict[str, float] | None:
 
 
 def probe_minimax(api_key: str) -> tuple[dict[str, float] | None, str | None]:
-    """Returns (usage_dict, error_reason). On success error_reason is None."""
+    """Returns (usage_dict, error_reason). On success error_reason is None.
+
+    API v2 shape (current): model_remains[].model_name with remaining_percent fields.
+    API v1 shape (legacy):  category_remains[].category == "text_generation" with count fields.
+    Tries v2 first; falls back to v1.
+    """
     try:
         req = urllib.request.Request(
             "https://www.minimax.io/v1/token_plan/remains",
@@ -131,6 +136,20 @@ def probe_minimax(api_key: str) -> tuple[dict[str, float] | None, str | None]:
         if status != 0:
             msg = data.get("base_resp", {}).get("status_msg", "unknown")
             return None, f"API status_code={status} ({msg})"
+
+        # v2: model_remains with remaining_percent fields (general = text)
+        for entry in data.get("model_remains", []):
+            if entry.get("model_name") == "general":
+                result = {}
+                ih = entry.get("current_interval_remaining_percent")
+                wh = entry.get("current_weekly_remaining_percent")
+                if ih is not None:
+                    result["five_hour"] = 100.0 - float(ih)
+                if wh is not None:
+                    result["seven_day"] = 100.0 - float(wh)
+                return (result or None), None
+
+        # v1 fallback: category_remains with count fields
         for cat in data.get("category_remains", []):
             if cat.get("category") == "text_generation":
                 result = {}
@@ -143,7 +162,8 @@ def probe_minimax(api_key: str) -> tuple[dict[str, float] | None, str | None]:
                 if weekly_total > 0:
                     result["seven_day"] = float(weekly_used) / float(weekly_total) * 100.0
                 return (result or None), None
-        return None, "text_generation category not found in response"
+
+        return None, "no usable plan data in response (keys: " + ", ".join(data.keys()) + ")"
     except urllib.error.HTTPError as e:
         return None, f"HTTP {e.code} {e.reason}"
     except urllib.error.URLError as e: