feat: package Pi extensions as Bun workspaces

extensions/interactive-subagents/pi-extension/subagents/tmux.ts

@@ -0,0 +1,119 @@
+/**
+ * tmux surface backend.
+ *
+ * This module only implements tmux-specific terminal operations. Backend
+ * selection, command scripts, and exit polling live in surface.ts.
+ */
+import { execFile, execFileSync } from "node:child_process";
+import { promisify } from "node:util";
+
+const execFileAsync = promisify(execFile);
+const commandAvailability = new Map<string, boolean>();
+
+function hasCommand(command: string): boolean {
+  const cached = commandAvailability.get(command);
+  if (cached !== undefined) return cached;
+
+  let available = false;
+  try {
+    execFileSync("sh", ["-c", `command -v ${command}`], { stdio: "ignore" });
+    available = true;
+  } catch {
+    available = false;
+  }
+
+  commandAvailability.set(command, available);
+  return available;
+}
+
+export function isAvailable(): boolean {
+  return !!process.env.TMUX && hasCommand("tmux");
+}
+
+export function setupHint(): string {
+  return "Start pi inside tmux (`tmux new -A -s pi 'pi'`).";
+}
+
+function requireTmux(): void {
+  if (!isAvailable()) {
+    throw new Error(`tmux is required for this surface. ${setupHint()}`);
+  }
+}
+
+/** tmux layout used to keep sibling panes evenly sized. */
+const SUBAGENT_TMUX_LAYOUT = "even-horizontal";
+let rebalanceTimer: ReturnType<typeof setTimeout> | null = null;
+
+function rebalanceSurfaces(hintPane?: string): void {
+  const target = process.env.TMUX_PANE ?? hintPane;
+  if (!target) return;
+  if (rebalanceTimer) clearTimeout(rebalanceTimer);
+  rebalanceTimer = setTimeout(() => {
+    rebalanceTimer = null;
+    try {
+      execFileSync("tmux", ["select-layout", "-t", target, SUBAGENT_TMUX_LAYOUT], {
+        encoding: "utf8",
+      });
+    } catch {
+      // Pane/window may be gone; balancing is best-effort.
+    }
+  }, 120);
+}
+
+export function createSurface(name: string): string {
+  return createSurfaceSplit(name, "right", process.env.TMUX_PANE);
+}
+
+export function createSurfaceSplit(
+  name: string,
+  direction: "left" | "right" | "up" | "down",
+  fromSurface?: string,
+): string {
+  void name;
+  requireTmux();
+
+  const args = ["split-window", "-d"];
+  args.push(direction === "left" || direction === "right" ? "-h" : "-v");
+  if (direction === "left" || direction === "up") args.push("-b");
+  if (fromSurface) args.push("-t", fromSurface);
+  args.push("-P", "-F", "#{pane_id}");
+
+  const pane = execFileSync("tmux", args, { encoding: "utf8" }).trim();
+  if (!pane.startsWith("%")) {
+    throw new Error(`Unexpected tmux split-window output: ${pane}`);
+  }
+
+  rebalanceSurfaces(pane);
+  return pane;
+}
+
+export function sendCommand(surface: string, command: string): void {
+  requireTmux();
+  execFileSync("tmux", ["send-keys", "-t", surface, "-l", command], { encoding: "utf8" });
+  execFileSync("tmux", ["send-keys", "-t", surface, "Enter"], { encoding: "utf8" });
+}
+
+export function readScreen(surface: string, lines = 50): string {
+  requireTmux();
+  return execFileSync(
+    "tmux",
+    ["capture-pane", "-p", "-t", surface, "-S", `-${Math.max(1, lines)}`],
+    { encoding: "utf8" },
+  );
+}
+
+export async function readScreenAsync(surface: string, lines = 50): Promise<string> {
+  requireTmux();
+  const { stdout } = await execFileAsync(
+    "tmux",
+    ["capture-pane", "-p", "-t", surface, "-S", `-${Math.max(1, lines)}`],
+    { encoding: "utf8" },
+  );
+  return stdout;
+}
+
+export function closeSurface(surface: string): void {
+  requireTmux();
+  execFileSync("tmux", ["kill-pane", "-t", surface], { encoding: "utf8" });
+  rebalanceSurfaces();
+}