Add HTTP Basic Auth to textual-serve web dashboard

Browser prompts for username/password before showing the TUI.
Credentials from gniza.conf: WEB_USER (default: admin) + WEB_API_KEY.

- Monkey-patches textual-serve's aiohttp app with auth middleware
- Uses secrets.compare_digest for timing-safe comparison
- Install script generates credentials and prints them
- Skips auth if no WEB_API_KEY configured

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/install.sh

@@ -163,7 +163,10 @@ done
 enable_web="n"
 read -rp "Enable web dashboard (TUI in browser)? (y/n) [n]: " enable_web </dev/tty || true
 if [ "$enable_web" = "y" ] || [ "$enable_web" = "Y" ]; then
-    # Generate API key if not already set
+    # Set up web credentials
+    if ! grep -q "^WEB_USER=" "$CONFIG_DIR/gniza.conf" 2>/dev/null; then
+        echo 'WEB_USER="admin"' >> "$CONFIG_DIR/gniza.conf"
+    fi
     if ! grep -q "^WEB_API_KEY=" "$CONFIG_DIR/gniza.conf" 2>/dev/null || \
        [ -z "$(grep '^WEB_API_KEY=' "$CONFIG_DIR/gniza.conf" 2>/dev/null | sed 's/^WEB_API_KEY="//' | sed 's/"$//')" ]; then
         api_key="$(python3 -c 'import secrets; print(secrets.token_urlsafe(32))')"
@@ -172,10 +175,10 @@ if [ "$enable_web" = "y" ] || [ "$enable_web" = "Y" ]; then
         else
             echo "WEB_API_KEY=\"${api_key}\"" >> "$CONFIG_DIR/gniza.conf"
         fi
-        info "Generated Web API key: $api_key"
-        echo "Save this key -- you will need it to access the dashboard."
+        info "Web credentials:  user=admin  password=$api_key"
+        echo "Save these -- you will need them to access the dashboard."
     else
-        info "Web API key already configured."
+        info "Web credentials already configured."
     fi
     # Install systemd service
     if [ "$MODE" = "root" ]; then

tui/__main__.py

@@ -1,4 +1,7 @@
+import base64
 import os
+import re
+import secrets
 import socket
 import subprocess
 import sys
@@ -57,11 +60,43 @@ def _parse_web_args():
     return host, port
 
 
+def _load_web_credentials() -> tuple[str, str]:
+    """Load WEB_USER and WEB_API_KEY from gniza.conf."""
+    config_dir = os.environ.get("GNIZA_CONFIG_DIR", "")
+    if not config_dir:
+        # Detect from mode
+        if os.geteuid() == 0:
+            config_dir = "/etc/gniza"
+        else:
+            config_dir = os.path.join(
+                os.environ.get("XDG_CONFIG_HOME", os.path.expanduser("~/.config")),
+                "gniza",
+            )
+    conf_path = Path(config_dir) / "gniza.conf"
+    user = "admin"
+    api_key = ""
+    if conf_path.is_file():
+        kv_re = re.compile(r'^([A-Z_][A-Z0-9_]*)="(.*)"$')
+        for line in conf_path.read_text().splitlines():
+            m = kv_re.match(line.strip())
+            if m:
+                if m.group(1) == "WEB_USER":
+                    user = m.group(2)
+                elif m.group(1) == "WEB_API_KEY":
+                    api_key = m.group(2)
+    return user, api_key
+
+
 def main():
     if "--web" in sys.argv:
+        from aiohttp import web as aio_web
         from textual_serve.server import Server
 
         host, port = _parse_web_args()
+        web_user, web_key = _load_web_credentials()
+
+        if not web_key:
+            print("WARNING: No WEB_API_KEY in gniza.conf. Web dashboard is unprotected.")
 
         os.environ["PYTHONPATH"] = f"{_ROOT}:{os.environ.get('PYTHONPATH', '')}"
         os.environ["GNIZA_DIR"] = _ROOT
@@ -74,14 +109,49 @@ def main():
 
         public_url = f"http://{public_host}:{port}"
         print(f"GNIZA web: serving TUI at {public_url}")
+        if web_key:
+            print(f"GNIZA web: login with user={web_user!r}")
 
         server = Server(
-            f"python3 -m tui",
+            "python3 -m tui",
             host=host,
             port=port,
             title="GNIZA Backup",
             public_url=public_url,
         )
+
+        # Add HTTP Basic Auth middleware if API key is configured
+        if web_key:
+            _orig_make_app = server._make_app
+
+            async def _authed_make_app():
+                app = await _orig_make_app()
+
+                @aio_web.middleware
+                async def basic_auth(request, handler):
+                    auth_header = request.headers.get("Authorization", "")
+                    if auth_header.startswith("Basic "):
+                        try:
+                            decoded = base64.b64decode(auth_header[6:]).decode("utf-8")
+                            req_user, req_pass = decoded.split(":", 1)
+                            if (
+                                secrets.compare_digest(req_user, web_user)
+                                and secrets.compare_digest(req_pass, web_key)
+                            ):
+                                return await handler(request)
+                        except Exception:
+                            pass
+                    return aio_web.Response(
+                        status=401,
+                        headers={"WWW-Authenticate": 'Basic realm="GNIZA"'},
+                        text="Authentication required",
+                    )
+
+                app.middlewares.insert(0, basic_auth)
+                return app
+
+            server._make_app = _authed_make_app
+
         server.serve()
     else:
         app = GnizaApp()