extensions!

pi/files/agent/extensions/git-checkpoint.ts

@@ -0,0 +1,53 @@
+/**
+ * Git Checkpoint Extension
+ *
+ * Creates git stash checkpoints at each turn so /fork can restore code state.
+ * When forking, offers to restore code to that point in history.
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+export default function (pi: ExtensionAPI) {
+	const checkpoints = new Map<string, string>();
+	let currentEntryId: string | undefined;
+
+	// Track the current entry ID when user messages are saved
+	pi.on("tool_result", async (_event, ctx) => {
+		const leaf = ctx.sessionManager.getLeafEntry();
+		if (leaf) currentEntryId = leaf.id;
+	});
+
+	pi.on("turn_start", async () => {
+		// Create a git stash entry before LLM makes changes
+		const { stdout } = await pi.exec("git", ["stash", "create"]);
+		const ref = stdout.trim();
+		if (ref && currentEntryId) {
+			checkpoints.set(currentEntryId, ref);
+		}
+	});
+
+	pi.on("session_before_fork", async (event, ctx) => {
+		const ref = checkpoints.get(event.entryId);
+		if (!ref) return;
+
+		if (!ctx.hasUI) {
+			// In non-interactive mode, don't restore automatically
+			return;
+		}
+
+		const choice = await ctx.ui.select("Restore code state?", [
+			"Yes, restore code to that point",
+			"No, keep current code",
+		]);
+
+		if (choice?.startsWith("Yes")) {
+			await pi.exec("git", ["stash", "apply", ref]);
+			ctx.ui.notify("Code restored to checkpoint", "info");
+		}
+	});
+
+	pi.on("agent_end", async () => {
+		// Clear checkpoints after agent completes
+		checkpoints.clear();
+	});
+}