fix: v2.5.6 — Windows panes without sh, UI build without node on PATH

- Windows panes: a WinGet tmux runs native programs and there is no `sh`, so
  every pane's `sh -c` wrapper died at once ("Command failed: tmux set-option
  … mouse on"). paneArgv runs the CLI itself on win32, and a Terminal gets
  tmux's own default shell (newSession drops the `--` for an empty argv).
- Plugin UI build: client deps install with --ignore-scripts and tsc/vite run
  by the running node instead of `npm run build`. On Windows esbuild's
  postinstall went through cmd.exe with no `node` on the server's PATH, both
  installs failed, and Update now kept the previous UI. A test keeps the two
  build steps equal to client/package.json's build script.
- Update all: Atomics.wait instead of a `sleep` binary Windows lacks.

server/__tests__/plugin-bootstrap.test.js

@@ -455,14 +455,18 @@ describe("buildClient dependency install", () => {
     return root;
   }
 
-  // Records every npm invocation; `fails` names the subcommands that exit non-zero.
-  // A successful "run build" writes the dist/ the real Vite build would produce.
+  // Records every invocation — npm's as its args, node's as `node <script> …`;
+  // `fails` names the npm subcommands that exit non-zero. A successful vite
+  // build writes the dist/ the real one would produce.
   function fakeExec(calls, fails = []) {
-    return (_cmd, args, cwd) => {
+    return (cmd, args, cwd) => {
+      if (cmd === "node") {
+        calls.push(`node ${path.basename(args[0])} ${args.slice(1).join(" ")}`);
+        if (args[1] === "build") fs.mkdirSync(path.join(cwd, "dist"), { recursive: true });
+        return true;
+      }
       calls.push(args.join(" "));
-      if (fails.includes(args[0])) return false;
-      if (args[0] === "run") fs.mkdirSync(path.join(cwd, "dist"), { recursive: true });
-      return true;
+      return !fails.includes(args[0]);
     };
   }
 
@@ -489,10 +493,12 @@ describe("buildClient dependency install", () => {
     const result = buildClient({ rt: RT, root: fakeRoot(), exec: fakeExec(calls, ["ci"]) });
 
     assert.equal(result, "built");
-    assert.deepEqual(
-      calls.map((c) => c.split(" ")[0]),
-      ["ci", "install", "run"]
-    );
+    assert.deepEqual(calls, [
+      "ci --no-audit --no-fund --include=dev --ignore-scripts",
+      "install --no-audit --no-fund --include=dev --ignore-scripts",
+      "node tsc -b",
+      "node vite.js build",
+    ]);
   });
 
   it("installs devDependencies explicitly, because NODE_ENV=production omits them", () => {
@@ -521,11 +527,28 @@ describe("buildClient dependency install", () => {
 
     assert.equal(result, "failed");
     assert.equal(
-      calls.some((c) => c.startsWith("run")),
+      calls.some((c) => c.startsWith("node")),
       false,
       "the build must not run on a broken dependency tree"
     );
   });
+
+  it("builds with the running node, no lifecycle script and no PATH lookup (Windows)", () => {
+    // On Windows a script or a .bin shim runs through cmd.exe and needs `node`
+    // on PATH; the server's PATH lacked it, so esbuild's postinstall failed and
+    // every update kept the previous UI. The build here must equal the
+    // client's own "build" script, run without npm.
+    assert.equal(
+      JSON.parse(fs.readFileSync(path.join(__dirname, "..", "..", "client", "package.json")))
+        .scripts.build,
+      "tsc -b && vite build"
+    );
+    resetRuntime();
+    const calls = [];
+    buildClient({ rt: RT, root: fakeRoot(), exec: fakeExec(calls) });
+    assert.deepEqual(calls.slice(-2), ["node tsc -b", "node vite.js build"]);
+    assert.ok(calls.every((c) => !c.startsWith("run")));
+  });
 });
 
 describe("supersededBy — an old cache directory must not act", () => {

server/__tests__/pty-run.test.js

@@ -499,6 +499,15 @@ describe("pty-run", () => {
     return argv.slice(4);
   }
 
+  it("runs a Windows pane's command itself — no sh there — and a Terminal as tmux's default shell", () => {
+    const argv = ["C:\\Users\\u\\.local\\bin\\claude.exe", "--model", "opus"];
+    assert.deepEqual(pty.paneArgv(argv, "win32"), argv);
+    assert.deepEqual(pty.paneArgv(null, "win32"), []);
+    assert.equal(pty.paneArgv(argv, "linux")[0], "sh");
+    assert.deepEqual(pty.paneArgv(argv, "linux").slice(-3), argv);
+    assert.match(pty.paneArgv(null, "linux")[2], /exec "\$SHELL" -l$/);
+  });
+
   it("spawnRun starts the CLI only once the pane has its real size, argv untouched", () => {
     // A claude drawn at tmux's birth size duplicated its banner on the first
     // resize; the argv rides as positional parameters, never script text.

server/__tests__/tmux.test.js

@@ -41,6 +41,16 @@ describe("tmux wrapper", () => {
     );
   });
 
+  it("newSession with no argv leaves tmux its default shell (no trailing --)", () => {
+    const calls = [];
+    tmux.__setExecImpl((args) => {
+      calls.push(args);
+      return "";
+    });
+    tmux.newSession({ name: "agenthub-lane-1", cwd: "C:\\repo", argv: [] });
+    assert.deepEqual(calls[0], ["new-session", "-d", "-s", "agenthub-lane-1", "-c", "C:\\repo"]);
+  });
+
   it("newSession builds the correct argv", () => {
     const calls = [];
     tmux.__setExecImpl((args) => {

server/lib/pty-run.js

@@ -77,6 +77,23 @@ const WAIT_FOR_CLIENT =
   'i=0; while [ "$(tmux display -p -t "$TMUX_PANE" \'#{session_attached}\' 2>/dev/null)" = 0 ]' +
   " && [ $i -lt 20 ]; do sleep 0.1; i=$((i+1)); done;";
 const CLIENT_WAIT_MS = 2000;
+
+/**
+ * A pane's tmux command: `argv` behind {@link WAIT_FOR_CLIENT}, or — with no
+ * `argv` — the login shell behind it. Windows has no `sh` (a WinGet tmux runs
+ * native programs), and an `sh -c` there died at once and took the session
+ * with it, so it gets the command itself, or nothing for tmux's own default
+ * shell.
+ * ponytail: no wait for the attach on Windows, so a pane may first draw at
+ * 80×24 (issue #55); port the wait to PowerShell if that shows.
+ */
+function paneArgv(argv, platform = process.platform) {
+  if (platform === "win32") return argv || [];
+  // argv rides as sh's positional parameters, never inside the script text.
+  return argv
+    ? ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$@"`, "sh", ...argv]
+    : ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$SHELL" -l`];
+}
 const CODEX_SANDBOXES = new Set(["read-only", "workspace-write", "danger-full-access"]);
 const CODEX_APPROVALS = new Set(["on-request", "never"]);
 // Codex has no `--effort` flag; reasoning effort is a config override.
@@ -493,13 +510,7 @@ function spawnRun(args) {
   };
 
   if (!tmux.hasSession(id)) {
-    // argv rides as sh's positional parameters, never inside the script text.
-    tmux.newSession({
-      name: id,
-      cwd,
-      argv: ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$@"`, "sh", ...argv],
-      env,
-    });
+    tmux.newSession({ name: id, cwd, argv: paneArgv(argv), env });
     record();
     schedulePaste();
   } else if (SHELL_COMMANDS.has(tmux.paneCommand(id) || "")) {
@@ -554,12 +565,7 @@ function spawnShell({ laneId, slot = 0, cwd }) {
   };
   // Started once the pane has its real size (WAIT_FOR_CLIENT, issue #55), as
   // the login shell tmux would have run (tmux sets SHELL in the pane).
-  tmux.newSession({
-    name: id,
-    cwd,
-    argv: ["sh", "-c", `${WAIT_FOR_CLIENT} exec "$SHELL" -l`],
-    env,
-  });
+  tmux.newSession({ name: id, cwd, argv: paneArgv(null), env });
   dashboardRuns?.recordRun({
     id,
     sessionId: null,
@@ -636,4 +642,5 @@ module.exports = {
   runIdForLane,
   MAX_PANE_SLOT,
   SHELL_COMMANDS,
+  paneArgv,
 };

server/lib/tmux.js

@@ -76,7 +76,9 @@ function envFlags(env) {
  * guessing from cwd — see resolveLaneArg in bin/agenthub.js.
  */
 function newSession({ name, cwd, argv, env }) {
-  execImpl(["new-session", "-d", "-s", name, "-c", cwd, ...envFlags(env), "--", ...argv]);
+  // No argv = tmux's own default shell (a Windows Terminal pane).
+  const cmd = argv.length ? ["--", ...argv] : [];
+  execImpl(["new-session", "-d", "-s", name, "-c", cwd, ...envFlags(env), ...cmd]);
   try {
     enableMouse(name);
   } catch (err) {
@@ -85,7 +87,9 @@ function newSession({ name, cwd, argv, env }) {
     // "Command failed: tmux set-option …" that hid the real problem.
     if (hasSession(name)) throw err;
     throw Object.assign(
-      new Error(`the session's command exited as soon as it started: ${argv[0]}`),
+      new Error(
+        `the session's command exited as soon as it started: ${argv[0] || "the default shell"}`
+      ),
       { code: "EPANEEXITED" }
     );
   }