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/src/utils/deprecation.ts

@@ -0,0 +1,14 @@
+import chalk from "chalk";
+
+const emittedDeprecationWarnings = new Set<string>();
+
+export function warnDeprecation(message: string): void {
+	if (emittedDeprecationWarnings.has(message)) return;
+	emittedDeprecationWarnings.add(message);
+	console.warn(chalk.yellow(`Deprecation warning: ${message}`));
+}
+
+/** Clear deprecation warning state. Exported for tests. */
+export function clearDeprecationWarningsForTests(): void {
+	emittedDeprecationWarnings.clear();
+}