Add staged change summarizer prompt.

prompts/summarize_staged

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+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."
+MODEL="gemini-3-flash-preview"
+FALLBACK="claude-sonnet-4.6"
+
+context() {
+  code2prompt $(git diff --name-only --cached | sed 's/.*/-i "&"/') .
+}
+
+diff() {
+  git diff --cached
+}
+
+aicli \
+  -m "$MODEL" \
+  -b "$FALLBACK" \
+  -sf "$SYSTEM_PROMPT_FILE" \
+  -p "$PROMPT" \
+  -p "DIFF:\n\n$(diff)" \
+  -p "AFTER CODE:\n\n$(context)" |
+  glow -p