diff --git a/scripts/generate_reports.py b/scripts/generate_reports.py
index 265da2d..a45e4eb 100644
--- a/scripts/generate_reports.py
+++ b/scripts/generate_reports.py
@@ -15,6 +15,7 @@ DB_PATH = Path("database/ngxstat.db")
 OUTPUT_DIR = Path("output")
 TEMPLATE_DIR = Path("templates")
 REPORT_CONFIG = Path("reports.yml")
+GENERATED_MARKER = OUTPUT_DIR / "generated.txt"
 
 # Mapping of interval names to SQLite strftime formats.  These strings are
 # substituted into report queries whenever the special ``{bucket}`` token is
@@ -30,6 +31,18 @@ INTERVAL_FORMATS = {
 app = typer.Typer(help="Generate aggregated log reports")
 
 
+@app.callback()
+def _cli_callback(ctx: typer.Context) -> None:
+    """Register post-command hook to note generation time."""
+
+    def _write_marker() -> None:
+        OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+        timestamp = datetime.utcnow().strftime("%Y-%m-%d %H:%M:%S")
+        GENERATED_MARKER.write_text(f"{timestamp}\n")
+
+    ctx.call_on_close(_write_marker)
+
+
 def _get_domains() -> List[str]:
     """Return a sorted list of unique domains from the logs table."""
     conn = sqlite3.connect(DB_PATH)
diff --git a/tests/test_reports.py b/tests/test_reports.py
index f9399df..fa8f0a0 100644
--- a/tests/test_reports.py
+++ b/tests/test_reports.py
@@ -2,8 +2,10 @@ import sqlite3
 from pathlib import Path
 import json
 import sys
+from datetime import datetime
 
 import pytest
+from typer.testing import CliRunner
 
 REPO_ROOT = Path(__file__).resolve().parents[1]
 sys.path.append(str(REPO_ROOT))
@@ -199,9 +201,23 @@ def test_generate_root_index(tmp_path, sample_reports, monkeypatch):
     assert '<option value="Global">' not in content
     assert '<option value="analysis">' not in content
 
-    # check for domain options
-    assert '<option value="foo.com">' in content
-    assert '<option value="bar.com">' in content
+
+def test_generated_marker_written(tmp_path, monkeypatch):
+    out_dir = tmp_path / "output"
+    monkeypatch.setattr(gr, "OUTPUT_DIR", out_dir)
+    monkeypatch.setattr(gr, "TEMPLATE_DIR", REPO_ROOT / "templates")
+    monkeypatch.setattr(gr, "GENERATED_MARKER", out_dir / "generated.txt")
+    monkeypatch.setattr(gr, "_copy_icons", lambda: None)
+    (out_dir / "hourly").mkdir(parents=True)
+
+    runner = CliRunner()
+    result = runner.invoke(gr.app, ["index"])
+    assert result.exit_code == 0, result.output
+
+    marker = out_dir / "generated.txt"
+    assert marker.exists()
+    content = marker.read_text().strip()
+    datetime.strptime(content, "%Y-%m-%d %H:%M:%S")
 
 
 def test_global_reports_once(tmp_path, sample_reports, monkeypatch):