Updated frontend running dev mode using deno/npm/bun as well. Additional dev mode Caddyfile to go https://localhost/.

caddy/Caddyfile.dev

@@ -0,0 +1,10 @@
+localhost {
+	# Forwards API by caddy, bypassing the Vite dev proxy
+	# Avoids bug https://github.com/oven-sh/bun/issues/9882
+	handle /api/* {
+		reverse_proxy :4402   # directly to backend
+	}
+	handle {
+		reverse_proxy :4403   # vite dev server
+	}
+}

passkey/util/frontend.py

@@ -1,8 +1,36 @@
+import atexit
+import shutil
+import signal
+import subprocess
 from importlib import resources
 from pathlib import Path
+from sys import stderr
+from threading import Thread
 
 __all__ = ["path", "file", "run_dev"]
 
+NO_FRONTEND_TOOL = """\
+┃ ⚠️  deno, npm or bunx needed to run the frontend server.
+"""
+
+BUN_BUG = """\
+┃ ⚠️  Bun cannot correctly proxy API requests to the backend.
+┃ Bug report: https://github.com/oven-sh/bun/issues/9882
+┃
+┃ Options:
+┃   - sudo caddy run --config caddy/Caddyfile.dev
+┃   - Install deno or npm instead
+┃
+┃ Caddy will skip the Vite for API calls and serve everything at port 443.
+┃ Otherwise Vite serves at port 8077 and proxies to backend (broken with bun).
+"""
+
+NO_FRONTEND = """\
+┃
+┃ Note: only static build of the frontend is served at port 8078.
+┃ The page will not update with frontend code changes.
+"""
+
 
 def _resolve_static_dir() -> Path:
     # Try packaged path via importlib.resources (works for wheel/installed).
@@ -26,12 +54,7 @@ def file(*parts: str) -> Path:
 
 
 def run_dev():
-    """Spawn the frontend dev server (bun or npm) as a background process."""
+    """Spawn the frontend dev server (deno, npm, or bunx) as a background process."""
-    import atexit
-    import shutil
-    import signal
-    import subprocess
-
     devpath = Path(__file__).parent.parent.parent / "frontend"
     if not (devpath / "package.json").exists():
         raise RuntimeError(
@@ -39,22 +62,47 @@ def run_dev():
             if "site-packages" in devpath.parts
             else f"Frontend source code not found at {devpath}"
         )
-    bun = shutil.which("bun")
-    npm = shutil.which("npm") if bun is None else None
-    if not bun and not npm:
-        raise RuntimeError("Neither bun nor npm found on PATH for dev server")
-    cmd: list[str] = [bun, "--bun", "run", "dev"] if bun else [npm, "run", "dev"]  # type: ignore[list-item]
-    proc = subprocess.Popen(cmd, cwd=str(devpath))
 
-    def _terminate():
+    options = [
-        if proc.poll() is None:
+        ("deno", "run", "dev"),
-            proc.terminate()
+        ("npm", "run", "dev", "--"),
+        ("bunx", "--bun", "vite"),
+    ]
+    cmd = None
+    tool_name = None
+    for option in options:
+        if tool := shutil.which(option[0]):
+            cmd = [tool, *option[1:]]
+            tool_name = option[0]
+            break
 
-    atexit.register(_terminate)
+    vite_process = None
 
-    def _signal_handler(signum, frame):
+    def start_vite():
-        _terminate()
+        nonlocal vite_process
-        raise SystemExit(0)
+        if cmd is None:
+            stderr.write(NO_FRONTEND_TOOL)
+            stderr.write(NO_FRONTEND)
+            return
+        assert tool_name is not None
+        try:
+            if tool_name == "bunx":
+                stderr.write(BUN_BUG)
 
-    for sig in (signal.SIGINT, signal.SIGTERM):
+            stderr.write(f">>> {' '.join([tool_name, *cmd[1:]])}\n")
-        signal.signal(sig, _signal_handler)
+            vite_process = subprocess.Popen(cmd, cwd=str(devpath), shell=False)
+        except Exception as e:
+            stderr.write(f"┃ ⚠️  Vite couldn't start: {e}\n")
+            stderr.write(NO_FRONTEND)
+
+    def cleanup():
+        vite_process.terminate()
+        vite_process.wait()
+
+    # Start Vite in a separate thread
+    vite_thread = Thread(target=start_vite, daemon=True)
+    vite_thread.start()
+
+    atexit.register(cleanup)
+    signal.signal(signal.SIGTERM, lambda *_: cleanup())
+    signal.signal(signal.SIGINT, lambda *_: cleanup())