diff --git a/python/commands/jlcpcb_downloader.py b/python/commands/jlcpcb_downloader.py
index dfd5be3..39a2911 100644
--- a/python/commands/jlcpcb_downloader.py
+++ b/python/commands/jlcpcb_downloader.py
@@ -412,6 +412,29 @@ def _download_official(target: Path, force: bool, progress: ProgressFn) -> Dict[
     )
 
 
+# Warn if the catalog is older than this (CDFER's pipeline has stalled for
+# weeks at a time, so a "fresh download" can still be stale data).
+STALE_AFTER_DAYS = 14
+
+
+def _catalog_age_days(last_modified: Optional[str]) -> Optional[int]:
+    """Parse an HTTP Last-Modified date and return its age in whole days."""
+    if not last_modified:
+        return None
+    try:
+        from email.utils import parsedate_to_datetime
+        from datetime import datetime, timezone
+
+        dt = parsedate_to_datetime(last_modified)
+        if dt is None:
+            return None
+        if dt.tzinfo is None:
+            dt = dt.replace(tzinfo=timezone.utc)
+        return max(0, (datetime.now(timezone.utc) - dt).days)
+    except (TypeError, ValueError):
+        return None
+
+
 def _result(
     source: str,
     target: Path,
@@ -421,7 +444,7 @@ def _result(
     last_modified: Optional[str],
 ) -> Dict[str, Any]:
     db_size_mb = round(target.stat().st_size / (1024 * 1024), 2) if target.exists() else 0
-    return {
+    result: Dict[str, Any] = {
         "success": True,
         "source": source,
         "total_parts": total,
@@ -431,6 +454,19 @@ def _result(
         "db_path": str(target),
         "catalog_last_modified": last_modified,
     }
+    age_days = _catalog_age_days(last_modified)
+    if age_days is not None:
+        result["catalog_age_days"] = age_days
+        if age_days >= STALE_AFTER_DAYS:
+            warning = (
+                f"Catalog from '{source}' is ~{age_days} days old (dated {last_modified}). "
+                "Its upstream pipeline may have stalled. For fresher data, re-run with "
+                "source='yaqwsx' (needs a 7z CLI) or source='official' (needs JLCPCB API creds)."
+            )
+            result["stale"] = True
+            result["warning"] = warning
+            logger.warning(warning)
+    return result
 
 
 # ---------------------------------------------------------------------------
diff --git a/src/tools/jlcpcb-api.ts b/src/tools/jlcpcb-api.ts
index 8456311..d8f927c 100644
--- a/src/tools/jlcpcb-api.ts
+++ b/src/tools/jlcpcb-api.ts
@@ -41,13 +41,18 @@ provider. Re-run with force=true to refresh.`,
                 `✓ Successfully downloaded JLCPCB parts database\n\n` +
                 `Source: ${result.source}\n` +
                 (result.catalog_last_modified
-                  ? `Catalog dated: ${result.catalog_last_modified}\n`
+                  ? `Catalog dated: ${result.catalog_last_modified}` +
+                    (typeof result.catalog_age_days === "number"
+                      ? ` (~${result.catalog_age_days} days old)`
+                      : "") +
+                    `\n`
                   : "") +
                 `Total parts: ${result.total_parts}\n` +
                 `Basic parts: ${result.basic_parts}\n` +
                 `Extended parts: ${result.extended_parts}\n` +
                 `Database size: ${result.db_size_mb} MB\n` +
-                `Database path: ${result.db_path}`,
+                `Database path: ${result.db_path}` +
+                (result.warning ? `\n\n⚠ ${result.warning}` : ""),
             },
           ],
         };
diff --git a/tests/test_jlcpcb_downloader.py b/tests/test_jlcpcb_downloader.py
index b6f92e8..e306e1a 100644
--- a/tests/test_jlcpcb_downloader.py
+++ b/tests/test_jlcpcb_downloader.py
@@ -170,3 +170,40 @@ def test_download_database_prefer_cdfer_converts(tmp_path, monkeypatch):
     assert result["basic_parts"] == 1
     assert result["catalog_last_modified"].startswith("Thu, 02 Apr 2026")
     assert (tmp_path / "jlcpcb_parts.db").exists()
+
+
+def _http_date(days_ago: int) -> str:
+    from datetime import datetime, timedelta, timezone
+    from email.utils import format_datetime
+
+    return format_datetime(datetime.now(timezone.utc) - timedelta(days=days_ago))
+
+
+def test_result_flags_stale_catalog_and_leaves_fresh_alone(tmp_path, monkeypatch):
+    """A catalog older than STALE_AFTER_DAYS must be flagged; a fresh one must not."""
+    monkeypatch.setattr(
+        jlcpcb_downloader.PlatformHelper, "get_data_dir", staticmethod(lambda: tmp_path)
+    )
+
+    def _fake_cdfer_dated(http_date):
+        def _impl(cache_dir, progress=None):
+            cache_dir.mkdir(parents=True, exist_ok=True)
+            src = cache_dir / "cdfer.sqlite3"
+            _make_cdfer_like_source(src)
+            return src, http_date
+
+        return _impl
+
+    # Stale: 60 days old
+    monkeypatch.setattr(jlcpcb_downloader, "download_cdfer", _fake_cdfer_dated(_http_date(60)))
+    stale = jlcpcb_downloader.download_database(prefer_source="cdfer")
+    assert stale.get("stale") is True
+    assert "warning" in stale
+    assert stale["catalog_age_days"] >= jlcpcb_downloader.STALE_AFTER_DAYS
+
+    # Fresh: 1 day old
+    monkeypatch.setattr(jlcpcb_downloader, "download_cdfer", _fake_cdfer_dated(_http_date(1)))
+    fresh = jlcpcb_downloader.download_database(prefer_source="cdfer")
+    assert fresh.get("stale") is not True
+    assert "warning" not in fresh
+    assert fresh["catalog_age_days"] <= 1