fix(checkpoints): derive the tag wait from the VPG's cadence (#12)

hooks/zerto_guard_hook.py

@@ -24,7 +24,7 @@ tagged checkpoint and waits for the Zerto task to reach Completed.
      "matcher": "mcp__.*",
      "hooks": [{"type": "command",
                 "command": "/path/to/.venv/bin/python /path/to/hooks/zerto_guard_hook.py",
-                "timeout": 180}]}]}}
+                "timeout": 360}]}]}}
 """
 
 from __future__ import annotations
@@ -40,7 +40,11 @@ LOG = os.environ.get("ZERTO_HOOK_LOG", os.path.expanduser("~/.zerto-guard-hook.l
 # Seconds the hook will wait for the checkpoint. Must stay under the hook
 # timeout configured in settings.json, or the host cancels us and the tool
 # call proceeds unguarded through the normal permission flow.
-GUARD_TIMEOUT_S = float(os.environ.get("ZERTO_HOOK_GUARD_TIMEOUT", "150"))
+# Must exceed the largest tag wait the guard can take. That is now derived from
+# the VPG's checkpoint cadence and capped at 300s (MAX_TAG_TIMEOUT_S), because a
+# tag takes ~128s to surface on an AWS-protected VPG. Too small a budget here
+# just moves the false denial from the guard into the hook.
+GUARD_TIMEOUT_S = float(os.environ.get("ZERTO_HOOK_GUARD_TIMEOUT", "330"))
 UNKNOWN_DECISION = os.environ.get("ZERTO_HOOK_UNKNOWN", "prompt")  # prompt | allow | deny