@

feat(api): require api_key when binding to all interfaces (parity with WS gateway)

The OpenAI-compatible API server had no authentication option, unlike the
WebSocket gateway which already refuses wildcard binds without a token.
When bound to 0.0.0.0, any caller who could reach the port could drive
the agent with its default tool posture.

- Add api_key field to ApiConfig (schema.py).
- Add wildcard_host_requires_auth validator that rejects wildcard binds
  without api_key, mirroring the WS gateway pattern.
- Add Bearer-token auth middleware to the API server (server.py).
  /health remains unauthenticated.
- Replace the wildcard-host CLI warning with a hard error when api_key
  is unset, and pass api_key to create_app.

Fixes #4490
@

nanobot/api/server.py

@@ -8,6 +8,7 @@ from __future__ import annotations
 
 import asyncio
 import contextlib
+import hmac
 import json as _json
 import time
 import uuid
@@ -392,7 +393,10 @@ async def handle_health(request: web.Request) -> web.Response:
 
 
 def create_app(
-    agent_loop, model_name: str = "nanobot", request_timeout: float = 120.0
+    agent_loop,
+    model_name: str = "nanobot",
+    request_timeout: float = 120.0,
+    api_key: str = "",
 ) -> web.Application:
     """Create the aiohttp application.
 
@@ -400,6 +404,7 @@ def create_app(
         agent_loop: An initialized AgentLoop instance.
         model_name: Model name reported in responses.
         request_timeout: Per-request timeout in seconds.
+        api_key: Optional API key for Bearer-token authentication.
     """
     app = web.Application(client_max_size=20 * 1024 * 1024)  # 20MB for base64 images
     app["agent_loop"] = agent_loop
@@ -407,6 +412,27 @@ def create_app(
     app["request_timeout"] = request_timeout
     app["session_locks"] = {}  # per-user locks, keyed by session_key
 
+    @web.middleware
+    async def auth_middleware(request: web.Request, handler) -> web.StreamResponse:
+        if not api_key:
+            return await handler(request)
+        # Allow unauthenticated health checks.
+        if request.path == "/health":
+            return await handler(request)
+        auth = request.headers.get("Authorization", "")
+        if not auth.startswith("Bearer "):
+            return web.json_response(
+                {"error": "Missing Authorization header. Use: Bearer <api_key>"},
+                status=401,
+            )
+        if not hmac.compare_digest(auth[len("Bearer "):], api_key):
+            return web.json_response(
+                {"error": "Invalid API key"}, status=401,
+            )
+        return await handler(request)
+
+    app.middlewares.append(auth_middleware)
+
     app.router.add_post("/v1/chat/completions", handle_chat_completions)
     app.router.add_get("/v1/models", handle_models)
     app.router.add_get("/health", handle_health)

nanobot/cli/commands.py

@@ -798,14 +798,24 @@ def serve(
     console.print(f"  [cyan]Model[/cyan]    : {model_name}{preset_tag}")
     console.print("  [cyan]Session[/cyan]  : api:default")
     console.print(f"  [cyan]Timeout[/cyan]  : {timeout}s")
+    api_key = api_cfg.api_key.strip() if api_cfg.api_key else ""
     if host in {"0.0.0.0", "::"}:
+        if not api_key:
+            console.print(
+                "[red]Error: host is 0.0.0.0 (all interfaces) but api_key is not set. "
+                "Set api.api_key in config to prevent unauthenticated access.[/red]"
+            )
+            raise typer.Exit(1)
         console.print(
-            "[yellow]Warning:[/yellow] API is bound to all interfaces. "
-            "Only do this behind a trusted network boundary, firewall, or reverse proxy."
+            "[yellow]API is bound to all interfaces "
+            "(authentication required).[/yellow]"
         )
     console.print()
 
-    api_app = create_app(agent_loop, model_name=model_name, request_timeout=timeout)
+    api_app = create_app(
+        agent_loop, model_name=model_name, request_timeout=timeout,
+        api_key=api_key,
+    )
 
     async def on_startup(_app):
         await agent_loop._connect_mcp()

nanobot/config/schema.py

@@ -307,6 +307,18 @@ class ApiConfig(Base):
     host: str = "127.0.0.1"  # Safer default: local-only bind.
     port: int = 8900
     timeout: float = 120.0  # Per-request timeout in seconds.
+    api_key: str = Field(default="", repr=False)
+
+    @model_validator(mode="after")
+    def wildcard_host_requires_auth(self) -> "ApiConfig":
+        if self.host not in ("0.0.0.0", "::"):
+            return self
+        if self.api_key.strip():
+            return self
+        raise ValueError(
+            "host is 0.0.0.0 (all interfaces) but api_key is not set "
+            "- set api.api_key to prevent unauthenticated access"
+        )
 
 
 class GatewayConfig(Base):