feat: guided auto-install for missing agent CLIs

Offer install with default Yes on TTY; auto-install when non-interactive
(install/CI). Resolve binaries from npm global prefix after install.

myagents/launcher.py

@@ -8,6 +8,7 @@ import shlex
 import shutil
 import sqlite3
 import subprocess
+import sys
 from datetime import datetime
 from importlib.metadata import PackageNotFoundError, version
 from pathlib import Path
@@ -217,43 +218,130 @@ def _exec_tmux(backend: str, chat_cwd: Path, cmd: list[str]) -> None:
     raise SystemExit(proc.returncode)
 
 
-def _offer_install(config: dict) -> str | None:
-    """Interactively offer to install a missing backend CLI.
+def _is_interactive() -> bool:
+    """True when we can safely prompt the user (TTY, not CI)."""
+    if os.environ.get("CI", "").lower() in ("1", "true", "yes"):
+        return False
+    if os.environ.get("XIAOHE_ASSUME_YES", "").lower() in ("1", "true", "yes"):
+        return False
+    try:
+        return bool(sys.stdin.isatty() and sys.stderr.isatty())
+    except Exception:  # noqa: BLE001 — treat broken streams as non-interactive
+        return False
 
-    Only backends with a known one-shot installer (``install_cmd``) are
-    offered; others fall back to the manual ``not_found_msg``. Prompts on
-    /dev/tty so it also works when stdin is not a terminal. Returns the
-    resolved binary path after a successful install, else None.
-    """
+
+def _npm_global_bin() -> Path | None:
+    """Directory where ``npm install -g`` places binaries, if resolvable."""
+    npm = shutil.which("npm")
+    if not npm:
+        return None
+    try:
+        proc = subprocess.run(
+            [npm, "prefix", "-g"],
+            capture_output=True,
+            text=True,
+            timeout=30,
+            check=False,
+        )
+    except (OSError, subprocess.TimeoutExpired):
+        return None
+    prefix = (proc.stdout or "").strip()
+    if proc.returncode != 0 or not prefix:
+        return None
+    root = Path(prefix)
+    # Unix: <prefix>/bin; Windows npm usually puts shims in <prefix> itself.
+    if sys.platform == "win32":
+        return root
+    return root / "bin"
+
+
+def _resolve_installed_binary(config: dict) -> str | None:
+    """Resolve binary on PATH, then under the npm global prefix (post-install)."""
+    found = _resolve_backend_binary(config)
+    if found:
+        return found
+    names = (config["binary"], *config.get("alt_binaries", ()))
+    npm_bin = _npm_global_bin()
+    if not npm_bin or not npm_bin.is_dir():
+        return None
+    for name in names:
+        candidates = [npm_bin / name]
+        if sys.platform == "win32":
+            candidates.extend(
+                [npm_bin / f"{name}.cmd", npm_bin / f"{name}.exe"]
+            )
+        for cand in candidates:
+            if cand.is_file():
+                return str(cand)
+    return None
+
+
+def _run_install(config: dict) -> str | None:
+    """Run ``install_cmd`` and return the resolved binary path, or None."""
     install_cmd = config.get("install_cmd")
     if not install_cmd:
         return None
-    stderr_console.print(
-        f"[yellow]{config['binary']} not found.[/yellow] "
-        f"Install with [cyan]{shlex.join(install_cmd)}[/cyan] ?"
-    )
-    try:
-        answer = click.prompt(
-            "Install now? [y/N]", default="n", show_default=True, err=True
-        )
-    except (click.Abort, EOFError):
-        return None
-    if answer.strip().lower() not in ("y", "yes"):
-        return None
     installer = shutil.which(install_cmd[0])
     if not installer:
         stderr_console.print(
             f"[red]{install_cmd[0]} not found[/red] — cannot auto-install "
-            f"{config['binary']}. Install it manually."
+            f"{config['binary']}.\n"
+            "  Install Node.js (e.g. [cyan]brew install node[/cyan]), then run "
+            "[cyan]xiaohe ensure-deps[/cyan] or [cyan]xiaohe init[/cyan]."
         )
         return None
+    stderr_console.print(
+        f"[dim]Installing {config['binary']} via[/dim] "
+        f"[cyan]{shlex.join(install_cmd)}[/cyan] …"
+    )
     proc = subprocess.run([installer, *install_cmd[1:]], check=False)
     if proc.returncode != 0:
         stderr_console.print(
-            f"[red]Install failed (exit {proc.returncode}).[/red]"
+            f"[red]Install failed (exit {proc.returncode}).[/red]\n"
+            "  Fix the error above, then run [cyan]xiaohe ensure-deps[/cyan]."
         )
         return None
-    return _resolve_backend_binary(config)
+    return _resolve_installed_binary(config)
+
+
+def _offer_install(config: dict, *, yes: bool | None = None) -> str | None:
+    """Install a missing backend CLI (guided prompt, or auto when non-interactive).
+
+    Only backends with a known one-shot installer (``install_cmd``) are
+    offered; others fall back to the manual ``not_found_msg``.
+
+    ``yes``: True = install without asking; False = always prompt when
+    possible; None = auto (no prompt when non-interactive / CI).
+    Interactive default is Yes when the installer binary is on PATH.
+    """
+    install_cmd = config.get("install_cmd")
+    if not install_cmd:
+        return None
+
+    auto = bool(yes) if yes is not None else not _is_interactive()
+    if not auto:
+        stderr_console.print(
+            f"[yellow]{config['binary']} CLI is missing[/yellow] "
+            "(needed to launch this agent).\n"
+            f"  Will run: [cyan]{shlex.join(install_cmd)}[/cyan]"
+        )
+        default = "y" if shutil.which(install_cmd[0]) else "n"
+        prompt = (
+            "Install now? [Y/n]" if default == "y" else "Install now? [y/N]"
+        )
+        try:
+            answer = click.prompt(
+                prompt, default=default, show_default=False, err=True
+            )
+        except (click.Abort, EOFError):
+            return None
+        if answer.strip().lower() not in ("y", "yes", ""):
+            stderr_console.print(
+                "[dim]Skipped.[/dim] Later: [cyan]xiaohe ensure-deps[/cyan] "
+                "or [cyan]xiaohe init[/cyan]."
+            )
+            return None
+    return _run_install(config)
 
 
 def backend_available(backend: str) -> bool:
@@ -262,20 +350,21 @@ def backend_available(backend: str) -> bool:
     return bool(cfg and _resolve_backend_binary(cfg))
 
 
-def ensure_backend(backend: str) -> bool:
-    """Ensure a backend CLI is available, offering to install it when missing.
+def ensure_backend(backend: str, *, yes: bool | None = None) -> bool:
+    """Ensure a backend CLI is available, installing it when missing.
 
-    Reuses the interactive ``_offer_install`` (prompt on tty, install via the
-    backend's ``install_cmd``). Backends without an installer (e.g. hermes)
-    fall back to the manual not-found message. Returns True if the CLI is
-    available afterwards.
+    Guided by default: prompts on a TTY (default Yes when npm is available).
+    Non-interactive contexts (install scripts, CI, piped stdin) install
+    automatically when an ``install_cmd`` exists. Pass ``yes=True`` only for
+    explicit scripting. Backends without an installer (e.g. hermes) cannot
+    be auto-installed. Returns True if the CLI is available afterwards.
     """
     cfg = _BACKENDS.get(backend)
     if not cfg:
         return False
     if _resolve_backend_binary(cfg):
         return True
-    return _offer_install(cfg) is not None
+    return _offer_install(cfg, yes=yes) is not None
 
 
 def _launch(
@@ -289,7 +378,7 @@ def _launch(
     config = _BACKENDS[backend]
     binary = _resolve_backend_binary(config)
     if not binary and offer_install:
-        binary = _offer_install(config)
+        binary = _offer_install(config, yes=False)
     if not binary:
         stderr_console.print(config["not_found_msg"])
         raise SystemExit(127)

tests/test_ensure_backend.py

@@ -0,0 +1,105 @@
+"""Tests for myagents.launcher.ensure_backend / guided auto-install."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import patch
+
+from myagents import launcher as launcher_mod
+
+
+class TestEnsureBackend:
+    def test_already_available_skips_install(self) -> None:
+        with (
+            patch.object(
+                launcher_mod,
+                "_resolve_backend_binary",
+                return_value="/usr/bin/claude",
+            ),
+            patch.object(launcher_mod, "_offer_install") as offer,
+        ):
+            assert launcher_mod.ensure_backend("claude") is True
+            offer.assert_not_called()
+
+    def test_noninteractive_auto_installs(self) -> None:
+        with (
+            patch.object(
+                launcher_mod, "_resolve_backend_binary", return_value=None
+            ),
+            patch.object(launcher_mod, "_is_interactive", return_value=False),
+            patch.object(
+                launcher_mod, "_run_install", return_value="/opt/bin/claude"
+            ) as run_install,
+            patch.object(launcher_mod, "click") as click_mod,
+        ):
+            assert launcher_mod.ensure_backend("claude") is True
+            run_install.assert_called_once()
+            click_mod.prompt.assert_not_called()
+
+    def test_yes_true_skips_prompt(self) -> None:
+        with (
+            patch.object(
+                launcher_mod, "_resolve_backend_binary", return_value=None
+            ),
+            patch.object(
+                launcher_mod, "_run_install", return_value="/opt/bin/claude"
+            ) as run_install,
+            patch.object(launcher_mod, "click") as click_mod,
+        ):
+            assert launcher_mod.ensure_backend("claude", yes=True) is True
+            run_install.assert_called_once()
+            click_mod.prompt.assert_not_called()
+
+    def test_unknown_backend_false(self) -> None:
+        assert launcher_mod.ensure_backend("nope") is False
+
+    def test_hermes_cannot_auto_install(self) -> None:
+        with (
+            patch.object(
+                launcher_mod, "_resolve_backend_binary", return_value=None
+            ),
+            patch.object(launcher_mod, "_is_interactive", return_value=False),
+        ):
+            assert launcher_mod.ensure_backend("hermes") is False
+
+
+class TestResolveInstalledBinary:
+    def test_falls_back_to_npm_global_bin(self, tmp_path: Path) -> None:
+        bin_dir = tmp_path / "bin"
+        bin_dir.mkdir()
+        claude = bin_dir / "claude"
+        claude.write_text("#!/bin/sh\n")
+        claude.chmod(0o755)
+        cfg = launcher_mod._BACKENDS["claude"]
+        with (
+            patch.object(
+                launcher_mod, "_resolve_backend_binary", return_value=None
+            ),
+            patch.object(launcher_mod, "_npm_global_bin", return_value=bin_dir),
+        ):
+            assert launcher_mod._resolve_installed_binary(cfg) == str(claude)
+
+
+class TestOfferInstallGuided:
+    def test_interactive_default_yes_when_npm_present(self) -> None:
+        cfg = launcher_mod._BACKENDS["claude"]
+        with (
+            patch.object(launcher_mod, "_is_interactive", return_value=True),
+            patch.object(
+                launcher_mod.shutil, "which", return_value="/usr/bin/npm"
+            ),
+            patch.object(
+                launcher_mod, "_run_install", return_value="/opt/bin/claude"
+            ) as run_install,
+            patch.object(
+                launcher_mod.click,
+                "prompt",
+                return_value="y",
+            ) as prompt,
+        ):
+            assert (
+                launcher_mod._offer_install(cfg, yes=None) == "/opt/bin/claude"
+            )
+            prompt.assert_called_once()
+            assert prompt.call_args.kwargs.get("default") == "y"
+            run_install.assert_called_once()