Update prompt.

prompts/summarize_staged

@@ -2,7 +2,27 @@
 
 SCRIPT_DIR=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" &>/dev/null && pwd)
 SYSTEM_PROMPT_FILE="$SCRIPT_DIR/coder.md"
-PROMPT="Summarize the changes made in this diff, given the diff and the after state."
+PROMPT='
+Summarize the changes made in this diff, given the diff and the after code.
+The rest of the code repository is not provided.
+
+OUTPUT FORMAT:
+
+```
+# Digest
+
+one liner detailing what has been changed
+
+# Summary
+
+short paragraph summary of the changes made in the diff
+
+# Details
+
+detailed breakdown of the changes, grouped by topic
+```
+'
+
 MODEL="gemini-3-flash-preview"
 FALLBACK="claude-sonnet-4.6"