diff --git a/skills/ingest/scripts/ingest-semantic.py b/skills/ingest/scripts/ingest-semantic.py
index a7b527a..fd4888d 100755
--- a/skills/ingest/scripts/ingest-semantic.py
+++ b/skills/ingest/scripts/ingest-semantic.py
@@ -60,6 +60,15 @@ with open(raw_rel, "r", encoding="utf-8") as fh:
 if not source_text.strip():
     die("preflight", "source is empty: " + raw_rel)
 
+# --- pre-flight check: if the prompt exceeds context window, exit cleanly with stage:input ---
+# Conservative estimate: ~4 chars/token for mixed IT/EN text
+SAFETY_MARGIN = 4096  # room for system prompt + JSON response
+MAX_SOURCE_TOKENS = NUM_CTX - SAFETY_MARGIN
+MAX_SOURCE_CHARS = MAX_SOURCE_TOKENS * 4
+
+if len(source_text) > MAX_SOURCE_CHARS:
+    die("input", f"source too large ({len(source_text)} chars, limit ~{MAX_SOURCE_CHARS}). "
+                 f"Use the SPLIT directive or divide the document.")
 
 # --- read existing index to avoid duplicate slugs ---
 existing_entities = set()