1 files changed, 41 insertions, 0 deletions
diff --git a/src/paths.ts b/src/paths.ts
new file mode 100644
index 0000000..b008f4f
--- /dev/null
+++ b/src/paths.ts
@@ -0,0 +1,41 @@
+/**
+ * pi's agent config directory, and the file pi-browser-harness stores its
+ * `/browser-target` choice in.
+ *
+ * This extension reads that file so a single `/browser-target` decision governs
+ * both packages. It never writes it — the harness owns that setting, and two
+ * writers of one file is a bug waiting to happen.
+ *
+ * pi exports `getAgentDir()`, but resolving it here would be a *runtime* import
+ * of the host package from an installed extension's own tree. Every other pi
+ * import in this codebase is `import type` and erased at build time, so the
+ * three lines are replicated instead (pi's dist/config.js: `PI_CODING_AGENT_DIR`,
+ * CONFIG_DIR_NAME `.pi`). Same reasoning as pi-browser-harness/src/profile/paths.ts.
+ */
+
+import { homedir } from "node:os";
+import { join } from "node:path";
+
+/** pi's env override for the agent dir (APP_NAME.toUpperCase() + "_CODING_AGENT_DIR"). */
+const ENV_AGENT_DIR = "PI_CODING_AGENT_DIR";
+
+/**
+ * Expand a leading `~` exactly as pi's expandTildePath does — `~` and `~/…`
+ * only, never `~\…`, on every platform. Being more lenient here would look in a
+ * different directory than pi resolves from the same variable.
+ */
+const expandTildePiCompatible = (path: string): string => {
+  if (path === "~") return homedir();
+  if (path.startsWith("~/")) return homedir() + path.slice(1);
+  return path;
+};
+
+/** pi's agent config directory — `$PI_CODING_AGENT_DIR` or `~/.pi/agent`. */
+export const agentDir = (): string => {
+  const fromEnv = process.env[ENV_AGENT_DIR];
+  if (fromEnv) return expandTildePiCompatible(fromEnv);
+  return join(homedir(), ".pi", "agent");
+};
+
+/** Where pi-browser-harness persists the `/browser-target` choice. */
+export const targetFilePath = (): string => join(agentDir(), "browser-target.json");