chore(vendor): import pi 0.85.1

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/coding-agent/examples/extensions/status-line.ts

@@ -0,0 +1,32 @@
+/**
+ * Status Line Extension
+ *
+ * Demonstrates ctx.ui.setStatus() for displaying persistent status text in the footer.
+ * Shows turn progress with themed colors.
+ */
+
+import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
+
+export default function (pi: ExtensionAPI) {
+	let turnCount = 0;
+
+	pi.on("session_start", async (_event, ctx) => {
+		const theme = ctx.ui.theme;
+		ctx.ui.setStatus("status-demo", theme.fg("dim", "Ready"));
+	});
+
+	pi.on("turn_start", async (_event, ctx) => {
+		turnCount++;
+		const theme = ctx.ui.theme;
+		const spinner = theme.fg("accent", "●");
+		const text = theme.fg("dim", ` Turn ${turnCount}...`);
+		ctx.ui.setStatus("status-demo", spinner + text);
+	});
+
+	pi.on("turn_end", async (_event, ctx) => {
+		const theme = ctx.ui.theme;
+		const check = theme.fg("success", "✓");
+		const text = theme.fg("dim", ` Turn ${turnCount} complete`);
+		ctx.ui.setStatus("status-demo", check + text);
+	});
+}