diff --git a/src/tether/runtime/server.py b/src/tether/runtime/server.py
index 63e9ea3..14ba17c 100644
--- a/src/tether/runtime/server.py
+++ b/src/tether/runtime/server.py
@@ -866,6 +866,7 @@ def predict_from_base64(
         image_b64: str | None = None,
         instruction: str = "",
         state: list[float] | None = None,
+        image_wrist_b64: str | None = None,
     ) -> dict[str, Any]:
         """Predict from base64-encoded image (for HTTP API)."""
         image = None
@@ -879,6 +880,16 @@ def predict_from_base64(
             except Exception as e:
                 return {"error": f"Failed to decode image: {e}"}
 
+        # image_wrist_b64 is accepted for API compat: multi-camera VLAs route to
+        # Pi05DecomposedServer (which consumes it). TetherServer is single-camera
+        # and cannot, so the wrist image is dropped here — logged so the drop is
+        # visible, not silent.
+        if image_wrist_b64:
+            logger.debug(
+                "wrist image ignored: %s is single-camera (use a multi-camera "
+                "VLA / decomposed export to consume image_wrist).",
+                type(self).__name__,
+            )
         return self.predict(image=image, instruction=instruction, state=state)
 
     # ---------------------------------------------------------------
@@ -1063,6 +1074,7 @@ async def predict_from_base64_async(
         image_b64: str | None = None,
         instruction: str = "",
         state: list[float] | None = None,
+        image_wrist_b64: str | None = None,
     ) -> dict[str, Any]:
         """Async base64 entrypoint — decodes image, then routes through batching."""
         image = None
@@ -1075,6 +1087,14 @@ async def predict_from_base64_async(
             except Exception as e:
                 return {"error": f"Failed to decode image: {e}"}
 
+        # image_wrist_b64 accepted for API compat; single-camera base drops it
+        # (see predict_from_base64). Logged so the drop is visible, not silent.
+        if image_wrist_b64:
+            logger.debug(
+                "wrist image ignored: %s is single-camera (use a multi-camera "
+                "VLA / decomposed export to consume image_wrist).",
+                type(self).__name__,
+            )
         return await self.predict_async(image=image, instruction=instruction, state=state)
 
     async def run_batch(self, requests: list) -> list[dict[str, Any]]:
@@ -2115,7 +2135,7 @@ async def _heartbeat_loop():
             if _curate_consent.is_opted_in():
                 from tether.curate.uploader import Uploader as _CurateUploader
                 _curate_receipt = _curate_consent.load()
-                _curate_dry_run = os.environ.get("TETHER_CURATE_DRY_RUN", "").lower() in ("1", "true", "yes")
+                _curate_dry_run = _os.environ.get("TETHER_CURATE_DRY_RUN", "").lower() in ("1", "true", "yes")
                 _curate_uploader = _CurateUploader(
                     contributor_id=_curate_receipt.contributor_id,
                     tier=_curate_receipt.tier,
@@ -2686,7 +2706,7 @@ async def guard_status():
         })
 
     @app.post("/guard/reset")
-    async def guard_reset():
+    async def guard_reset(_auth: None = Depends(_require_api_key)):
         g = getattr(server, "_action_guard", None)
         if g is None:
             return JSONResponse(
diff --git a/tests/test_runtime_serve_hardening.py b/tests/test_runtime_serve_hardening.py
new file mode 100644
index 0000000..fa5dd68
--- /dev/null
+++ b/tests/test_runtime_serve_hardening.py
@@ -0,0 +1,240 @@
+"""Tests for the three runtime/server.py hardening fixes.
+
+Bug #1: /guard/reset was unauthenticated (no _require_api_key dependency).
+Bug #2: NameError: `os` inside the lifespan function that only imports `os as _os`.
+Bug #3: TypeError from `image_wrist_b64=` kwarg passed to predict_from_base64_async
+        which didn't accept that parameter.
+"""
+from __future__ import annotations
+
+import inspect
+import importlib.util
+import json
+import tempfile
+from pathlib import Path
+
+import pytest
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _build_minimal_export_dir(tmp_path):
+    """Minimal export dir so create_app() can instantiate without a real model."""
+    cfg = {
+        "model_id": "lerobot/smolvla_base",
+        "model_type": "smolvla",
+        "target": "desktop",
+        "action_chunk_size": 50,
+        "action_dim": 32,
+        "expert": {"expert_hidden": 720, "action_dim": 32, "num_layers": 16},
+    }
+    (tmp_path / "tether_config.json").write_text(json.dumps(cfg))
+    (tmp_path / "model.onnx").write_bytes(b"\x00")
+    return tmp_path
+
+
+def _server_py_path() -> Path:
+    return Path(__file__).resolve().parents[1] / "src" / "tether" / "runtime" / "server.py"
+
+
+# ---------------------------------------------------------------------------
+# Bug #1 — /guard/reset must require api-key auth
+# ---------------------------------------------------------------------------
+
+class TestGuardResetAuth:
+    """Verify the /guard/reset route has _require_api_key in its dependencies."""
+
+    def _get_guard_reset_route(self):
+        """Build the app and find the /guard/reset route object."""
+        if importlib.util.find_spec("fastapi") is None:
+            pytest.skip("fastapi not installed")
+
+        from tether.runtime.server import create_app
+
+        with tempfile.TemporaryDirectory() as d:
+            p = Path(d)
+            cfg = {
+                "model_id": "lerobot/smolvla_base",
+                "model_type": "smolvla",
+                "target": "desktop",
+                "action_chunk_size": 50,
+                "action_dim": 32,
+                "expert": {"expert_hidden": 720, "action_dim": 32, "num_layers": 16},
+            }
+            (p / "tether_config.json").write_text(json.dumps(cfg))
+            (p / "model.onnx").write_bytes(b"\x00")
+            app = create_app(str(p), device="cpu", api_key="test-key")
+
+        for route in app.routes:
+            path = getattr(route, "path", None)
+            methods = getattr(route, "methods", None) or set()
+            if path == "/guard/reset" and "POST" in methods:
+                return route
+        return None
+
+    def test_guard_reset_route_exists(self):
+        route = self._get_guard_reset_route()
+        assert route is not None, "/guard/reset POST route not found in app.routes"
+
+    def test_guard_reset_has_api_key_dependency(self):
+        """The /guard/reset endpoint's dependant should include _require_api_key."""
+        if importlib.util.find_spec("fastapi") is None:
+            pytest.skip("fastapi not installed")
+
+        route = self._get_guard_reset_route()
+        assert route is not None, "/guard/reset POST route not found"
+
+        # FastAPI stores dependencies in route.dependant.dependencies
+        dependant = getattr(route, "dependant", None)
+        assert dependant is not None, "route has no dependant"
+
+        dep_calls = [
+            dep.call.__name__ if callable(dep.call) else str(dep.call)
+            for dep in dependant.dependencies
+        ]
+        assert "_require_api_key" in dep_calls, (
+            f"/guard/reset dependencies do not include _require_api_key; "
+            f"found: {dep_calls}"
+        )
+
+    def test_guard_reset_rejects_unauthenticated(self, tmp_path):
+        """With api_key set, POST /guard/reset without header → 401."""
+        try:
+            from fastapi import FastAPI
+            from fastapi.testclient import TestClient
+        except ImportError:
+            pytest.skip("fastapi not installed")
+
+        # Build a minimal app that mirrors the three guarded endpoints
+        from fastapi import Depends, Header, HTTPException
+        from fastapi.responses import JSONResponse
+
+        app = FastAPI()
+        api_key = "secret-guard-key"
+
+        async def _require_api_key(
+            x_tether_key: str | None = Header(default=None, alias="X-Tether-Key"),
+        ) -> None:
+            if x_tether_key != api_key:
+                raise HTTPException(status_code=401, detail="bad key")
+
+        @app.post("/guard/reset")
+        async def guard_reset(_auth: None = Depends(_require_api_key)):
+            return JSONResponse(content={"reset": True, "was_tripped": False})
+
+        client = TestClient(app)
+        # No key → 401
+        assert client.post("/guard/reset").status_code == 401
+        # Correct key → 200
+        assert client.post(
+            "/guard/reset",
+            headers={"X-Tether-Key": api_key},
+        ).status_code == 200
+
+
+# ---------------------------------------------------------------------------
+# Bug #2 — no bare `os.` inside the lifespan / startup function
+# ---------------------------------------------------------------------------
+
+class TestOsNameInLifespan:
+    """Verify the lifespan function body has no bare `os.` (would NameError)."""
+
+    def test_no_bare_os_dot_in_server_py(self):
+        import re
+
+        src = _server_py_path().read_text()
+
+        # Match `os.` NOT preceded by underscore (i.e. not `_os.`).
+        # Exclude comment lines.
+        bare_os_lines = []
+        for i, line in enumerate(src.splitlines(), start=1):
+            stripped = line.lstrip()
+            if stripped.startswith("#"):
+                continue
+            if re.search(r"(?<!_)\bos\.", line):
+                bare_os_lines.append((i, line.rstrip()))
+
+        assert bare_os_lines == [], (
+            "Bare `os.` found in server.py (should be `_os.` inside lifespan "
+            f"which imports `import os as _os`): {bare_os_lines}"
+        )
+
+    def test_py_compile_server(self):
+        """server.py must compile without errors."""
+        import py_compile
+
+        path = str(_server_py_path())
+        # raises py_compile.PyCompileError on failure
+        py_compile.compile(path, doraise=True)
+
+
+# ---------------------------------------------------------------------------
+# Bug #3 — TetherServer.predict_from_base64_async accepts image_wrist_b64
+# ---------------------------------------------------------------------------
+
+class TestWristImageKwarg:
+    """TetherServer.predict_from_base64{,_async} must accept image_wrist_b64."""
+
+    def test_predict_from_base64_signature(self):
+        from tether.runtime.server import TetherServer
+        sig = inspect.signature(TetherServer.predict_from_base64)
+        assert "image_wrist_b64" in sig.parameters, (
+            f"TetherServer.predict_from_base64 missing image_wrist_b64 param; "
+            f"params: {list(sig.parameters)}"
+        )
+
+    def test_predict_from_base64_async_signature(self):
+        from tether.runtime.server import TetherServer
+        sig = inspect.signature(TetherServer.predict_from_base64_async)
+        assert "image_wrist_b64" in sig.parameters, (
+            f"TetherServer.predict_from_base64_async missing image_wrist_b64 param; "
+            f"params: {list(sig.parameters)}"
+        )
+
+    def test_predict_from_base64_async_accepts_wrist_kwarg(self, tmp_path):
+        """Calling predict_from_base64_async with image_wrist_b64 must not TypeError."""
+        import asyncio
+        import json as _json
+
+        cfg = {
+            "model_id": "lerobot/smolvla_base",
+            "model_type": "smolvla",
+            "target": "desktop",
+            "action_chunk_size": 50,
+            "action_dim": 32,
+            "expert": {"expert_hidden": 720, "action_dim": 32, "num_layers": 16},
+        }
+        (tmp_path / "tether_config.json").write_text(_json.dumps(cfg))
+
+        from tether.runtime.server import TetherServer
+        server = TetherServer(str(tmp_path), device="cpu")
+
+        # Server is not ready (no ONNX) — predict() will return an error dict,
+        # but the call must NOT raise TypeError for the wrist kwarg.
+        result = asyncio.run(
+            server.predict_from_base64_async(
+                image_b64=None,
+                instruction="test",
+                state=None,
+                image_wrist_b64=None,  # <-- was the TypeError trigger
+            )
+        )
+        # Should be a dict (error envelope is fine; TypeError is not)
+        assert isinstance(result, dict)
+
+    def test_callee_in_act_handler_accepts_wrist(self):
+        """The call site in server.py passes image_wrist_b64; callee must accept it.
+
+        Checks the actual call at line ~2342 passes a kwarg that now exists in
+        both TetherServer AND Pi05DecomposedServer predict_from_base64_async.
+        """
+        from tether.runtime.server import TetherServer
+        from tether.runtime.decomposed_server import Pi05DecomposedServer
+
+        for cls in (TetherServer, Pi05DecomposedServer):
+            sig = inspect.signature(cls.predict_from_base64_async)
+            assert "image_wrist_b64" in sig.parameters, (
+                f"{cls.__name__}.predict_from_base64_async missing image_wrist_b64"
+            )