Replace prompt-based PostToolUse hook with deterministic Python script

The prompt-based hook was unreliably blocking non-SV file writes (e.g. .ts
files) because the LLM would generate explanatory text instead of returning
a clean {}. The new deterministic script checks file extensions directly,
guaranteeing silent pass-through for non-SV files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: codejunkie99

plugins/gateflow/hooks/hooks.json

@@ -39,9 +39,9 @@
         "matcher": "Write|Edit",
         "hooks": [
           {
-            "type": "prompt",
-            "prompt": "Check if the file just written/edited is a SystemVerilog or Verilog file (.sv, .svh, .v, .vh). Return ONLY a JSON object. If it IS an SV/V file: {\"systemMessage\": \"SV file modified. Run /gf-lint to check for issues, or continue if you plan to lint later.\"}. If it is NOT an SV file: {}.",
-            "timeout": 10
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/hooks/scripts/posttooluse-sv-lint-nudge.py",
+            "timeout": 2
           }
         ]
       }

plugins/gateflow/hooks/scripts/posttooluse-sv-lint-nudge.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+"""GateFlow PostToolUse hook for Write/Edit events.
+
+Deterministic check: if the file just written/edited has a SystemVerilog or
+Verilog extension, remind the user to lint. For all other file types, silently
+pass through.
+"""
+
+from __future__ import annotations
+
+import json
+import sys
+from typing import Any, Dict
+
+
+SV_EXTENSIONS = (".sv", ".svh", ".v", ".vh")
+
+
+def main() -> int:
+    try:
+        payload: Dict[str, Any] = json.load(sys.stdin)
+    except Exception:
+        sys.stdout.write("{}")
+        return 0
+
+    tool_input = payload.get("tool_input", {}) or {}
+    file_path = tool_input.get("file_path", "") if isinstance(tool_input, dict) else ""
+
+    if isinstance(file_path, str) and file_path.lower().endswith(SV_EXTENSIONS):
+        out = {
+            "systemMessage": (
+                "SV file modified. Run /gf-lint to check for issues, "
+                "or continue if you plan to lint later."
+            )
+        }
+        sys.stdout.write(json.dumps(out))
+    else:
+        sys.stdout.write("{}")
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())