diff --git a/backend/routers/tools.py b/backend/routers/tools.py
index 0faa392..40bbba3 100644
--- a/backend/routers/tools.py
+++ b/backend/routers/tools.py
@@ -85,7 +85,30 @@ async def api_geocode_reverse(
     return await asyncio.to_thread(reverse_geocode, lat, lng, local_only)
 
 
-@router.get("/api/sentinel2/search")
+# ── Sentinel proxy routes (Issue #299/#300/#301, reported by tg12) ──────────
+# These three endpoints relay external Sentinel / Planetary Computer
+# requests through the backend to avoid browser CORS blocks. They are
+# operator-only helpers — they MUST NOT be callable by anonymous remote
+# users, because:
+#
+#   * /api/sentinel/token  — caller supplies their own Sentinel client_id +
+#     client_secret. Without operator gating, the backend becomes a free
+#     anonymous OAuth-mint relay for any Copernicus account.
+#   * /api/sentinel/tile   — same shape as the token route but for tile
+#     imagery. Without gating, the backend acts as an anonymous quota and
+#     bandwidth relay for Sentinel Hub Process API calls.
+#   * /api/sentinel2/search — hits the Planetary Computer STAC search API
+#     and falls back to Esri imagery. No caller credentials are involved,
+#     but the route is still an anonymous external-search relay. We gate
+#     it the same way for consistency with the rest of the operator-only
+#     helper surface.
+#
+# Gating is via require_local_operator (loopback / bridge / admin key),
+# matching the same allowlist already used by /api/region-dossier and
+# the other operator helpers further up this file. Single-operator nodes
+# see no behavior change — their dashboard already lives on loopback or
+# the trusted Docker bridge, so it still resolves.
+@router.get("/api/sentinel2/search", dependencies=[Depends(require_local_operator)])
 @limiter.limit("30/minute")
 def api_sentinel2_search(
     request: Request,
@@ -97,7 +120,7 @@ def api_sentinel2_search(
     return search_sentinel2_scene(lat, lng)
 
 
-@router.post("/api/sentinel/token")
+@router.post("/api/sentinel/token", dependencies=[Depends(require_local_operator)])
 @limiter.limit("60/minute")
 async def api_sentinel_token(request: Request):
     """Proxy Copernicus CDSE OAuth2 token request (avoids browser CORS block)."""
@@ -152,7 +175,7 @@ import os as _os
 _SH_TOKEN_CACHE_HMAC_KEY = _os.urandom(32)
 
 
-@router.post("/api/sentinel/tile")
+@router.post("/api/sentinel/tile", dependencies=[Depends(require_local_operator)])
 @limiter.limit("300/minute")
 async def api_sentinel_tile(request: Request):
     """Proxy Sentinel Hub Process API tile request (avoids CORS block)."""
diff --git a/backend/tests/test_control_surface_auth.py b/backend/tests/test_control_surface_auth.py
index 87915ac..187b2bd 100644
--- a/backend/tests/test_control_surface_auth.py
+++ b/backend/tests/test_control_surface_auth.py
@@ -89,6 +89,34 @@ import pytest
         # relay through the backend. 60/minute rate limit is not enough on
         # a streaming endpoint.
         ("get", "/api/radio/openmhz/audio?url=https%3A%2F%2Fmedia.openmhz.com%2Faudio%2Fabc.mp3", None),
+        # Issue #299 (tg12): /api/sentinel/token relays Copernicus CDSE
+        # OAuth token requests for caller-supplied client_id/secret.
+        # Anonymous access turns the backend into a free OAuth-mint relay.
+        (
+            "post",
+            "/api/sentinel/token",
+            None,  # body sent via raw form-encoded data — None lets the
+                   # remote_client wrapper send an empty body; the auth
+                   # check fires before the form parser runs.
+        ),
+        # Issue #300 (tg12): /api/sentinel/tile relays Sentinel Hub Process
+        # API tile fetches. Anonymous access is a bandwidth/quota relay
+        # for any caller's Copernicus account.
+        (
+            "post",
+            "/api/sentinel/tile",
+            {
+                "client_id": "ignored",
+                "client_secret": "ignored",
+                "preset": "TRUE-COLOR",
+                "date": "2026-01-01",
+                "z": 6, "x": 30, "y": 20,
+            },
+        ),
+        # Issue #301 (tg12): /api/sentinel2/search hits Planetary Computer
+        # STAC + Esri fallback. Anonymous access is a free external-search
+        # relay even though no caller credentials are involved.
+        ("get", "/api/sentinel2/search?lat=0&lng=0", None),
     ],
 )
 def test_remote_control_surface_rejects_without_local_operator_or_admin(
diff --git a/backend/tests/test_sentinel_routes_auth_gate.py b/backend/tests/test_sentinel_routes_auth_gate.py
new file mode 100644
index 0000000..da96017
--- /dev/null
+++ b/backend/tests/test_sentinel_routes_auth_gate.py
@@ -0,0 +1,231 @@
+"""Issues #299, #300, #301 (tg12): Sentinel proxy routes must require
+local-operator auth.
+
+Before the fix, three Sentinel proxy routes in ``backend/routers/tools.py``
+were decorated only with ``@limiter.limit(...)`` — no
+``Depends(require_local_operator)``:
+
+  * ``POST /api/sentinel/token``  — Copernicus CDSE OAuth relay for
+    caller-supplied client_id + client_secret. Anonymous access made the
+    backend a free OAuth-mint relay for any Sentinel account.
+  * ``POST /api/sentinel/tile``   — Sentinel Hub Process API relay.
+    Caller supplies their own credentials, backend mints a token if
+    needed and relays the PNG. Anonymous access was a bandwidth + quota
+    relay for any Copernicus account.
+  * ``GET  /api/sentinel2/search`` — Planetary Computer STAC search with
+    Esri imagery fallback. No caller credentials are involved, but the
+    route is still an anonymous external-search relay.
+
+The fix adds ``dependencies=[Depends(require_local_operator)]`` to each.
+The parameterized regression in ``test_control_surface_auth.py`` covers
+the basic 403 path. This file adds the harder property: when the auth
+gate fires, **the underlying upstream HTTP call never happens** — no
+outbound Copernicus token mint, no Sentinel Hub Process call, no
+Planetary Computer STAC search. The egress-on-403 property is what
+separates a real gate from a route that returns 403 *after* burning a
+quota.
+"""
+
+from __future__ import annotations
+
+import asyncio
+from unittest.mock import patch, MagicMock
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+
+
+# ---------------------------------------------------------------------------
+# Remote client fixture — same shape as test_control_surface_auth.py, but
+# inlined here so this file doesn't depend on the shared remote_client
+# fixture order. Uses 1.2.3.4 as the peer IP so loopback auth bypass
+# doesn't accidentally let the request through.
+# ---------------------------------------------------------------------------
+
+
+class _PeerClient:
+    """Raw ASGI client with a configurable peer IP. FastAPI's
+    ``TestClient`` reports ``request.client.host`` as ``"testclient"``
+    which isn't on the loopback allowlist — we need to set the peer
+    explicitly to exercise the real ``require_local_operator`` path.
+    """
+
+    def __init__(self, peer_ip: str):
+        from main import app
+
+        self._loop = asyncio.new_event_loop()
+        self._transport = ASGITransport(app=app, client=(peer_ip, 12345))
+        self._base = f"http://{peer_ip}:8000"
+
+    def _do(self, method: str, url: str, **kw):
+        async def go():
+            async with AsyncClient(transport=self._transport, base_url=self._base) as ac:
+                return await ac.request(method, url, **kw)
+
+        return self._loop.run_until_complete(go())
+
+    def get(self, url, **kw):
+        return self._do("GET", url, **kw)
+
+    def post(self, url, **kw):
+        return self._do("POST", url, **kw)
+
+    def close(self):
+        self._loop.close()
+
+
+@pytest.fixture
+def remote():
+    """Untrusted remote caller (1.2.3.4) — must hit the auth gate."""
+    client = _PeerClient("1.2.3.4")
+    yield client
+    client.close()
+
+
+@pytest.fixture
+def loopback():
+    """127.0.0.1 caller — must pass the gate exactly like the operator."""
+    client = _PeerClient("127.0.0.1")
+    yield client
+    client.close()
+
+
+# ---------------------------------------------------------------------------
+# /api/sentinel/token — issue #299
+# ---------------------------------------------------------------------------
+
+
+class TestSentinelTokenAuthGate:
+    def test_anonymous_caller_is_rejected(self, remote):
+        """A remote (non-loopback, non-bridge) caller MUST be rejected."""
+        r = remote.post(
+            "/api/sentinel/token",
+            data={"client_id": "anything", "client_secret": "anything"},
+        )
+        assert r.status_code == 403
+
+    def test_no_upstream_token_mint_on_403(self, remote):
+        """The Copernicus token endpoint must NOT be contacted when the
+        auth gate fires. This is what makes the gate real — without it,
+        a 403 returned *after* the upstream call still burns quota.
+
+        We patch ``requests.post`` at the module level so any outbound
+        token request would be intercepted. The mock is asserted to have
+        ZERO calls.
+        """
+        fake_post = MagicMock()
+        # If the gate is broken, the route would call requests.post; we
+        # want this MagicMock to make that fact loud.
+        fake_post.side_effect = AssertionError(
+            "requests.post was called despite auth-gate 403 — the gate is bypassable"
+        )
+        with patch("requests.post", fake_post):
+            r = remote.post(
+                "/api/sentinel/token",
+                data={"client_id": "anything", "client_secret": "anything"},
+            )
+        assert r.status_code == 403
+        assert fake_post.call_count == 0
+
+    def test_loopback_caller_passes_auth(self, loopback):
+        """A 127.0.0.1 caller must pass the gate. We don't care about
+        the upstream response shape — just that the request reaches the
+        handler (which would then try to talk to Copernicus). We patch
+        ``requests.post`` to return a 401 so the test doesn't hit the
+        real network.
+
+        Note: FastAPI's ``TestClient`` reports ``request.client.host``
+        as ``"testclient"`` by default, which is NOT on the loopback
+        allowlist (``127.0.0.1`` / ``::1`` / ``localhost``). The
+        ``loopback`` fixture below uses raw ASGI with an explicit
+        ``127.0.0.1`` peer IP so the auth gate sees real loopback.
+        """
+        fake_resp = MagicMock()
+        fake_resp.status_code = 401
+        fake_resp.content = b'{"error": "invalid_client"}'
+        with patch("requests.post", return_value=fake_resp):
+            r = loopback.post(
+                "/api/sentinel/token",
+                data={"client_id": "anything", "client_secret": "anything"},
+            )
+        # 200 (relayed), 401 (upstream said no), or 502 (upstream blew up)
+        # are all acceptable — what matters is we got past the auth gate
+        # (no 403). The route relays the upstream response status.
+        assert r.status_code != 403
+
+
+# ---------------------------------------------------------------------------
+# /api/sentinel/tile — issue #300
+# ---------------------------------------------------------------------------
+
+
+class TestSentinelTileAuthGate:
+    _VALID_BODY = {
+        "client_id": "anything",
+        "client_secret": "anything",
+        "preset": "TRUE-COLOR",
+        "date": "2026-01-01",
+        "z": 6,
+        "x": 30,
+        "y": 20,
+    }
+
+    def test_anonymous_caller_is_rejected(self, remote):
+        r = remote.post("/api/sentinel/tile", json=self._VALID_BODY)
+        assert r.status_code == 403
+
+    def test_no_upstream_call_on_403(self, remote):
+        """When the gate fires, neither the token mint nor the Process
+        API call should happen."""
+        fake_post = MagicMock(side_effect=AssertionError(
+            "requests.post was called despite auth-gate 403 — gate bypassable"
+        ))
+        with patch("requests.post", fake_post):
+            r = remote.post("/api/sentinel/tile", json=self._VALID_BODY)
+        assert r.status_code == 403
+        assert fake_post.call_count == 0
+
+
+# ---------------------------------------------------------------------------
+# /api/sentinel2/search — issue #301
+# ---------------------------------------------------------------------------
+
+
+class TestSentinel2SearchAuthGate:
+    def test_anonymous_caller_is_rejected(self, remote):
+        r = remote.get("/api/sentinel2/search?lat=0&lng=0")
+        assert r.status_code == 403
+
+    def test_no_upstream_search_on_403(self, remote):
+        """The Planetary Computer STAC search MUST NOT be called when
+        the gate fires."""
+        fake = MagicMock(side_effect=AssertionError(
+            "search_sentinel2_scene was called despite 403 — gate bypassable"
+        ))
+        # Patch the underlying service function — that's the network
+        # surface. If the auth dep fires first, the handler body never
+        # runs and this stays uncalled.
+        with patch("services.sentinel_search.search_sentinel2_scene", fake):
+            r = remote.get("/api/sentinel2/search?lat=0&lng=0")
+        assert r.status_code == 403
+        assert fake.call_count == 0
+
+    def test_loopback_caller_reaches_handler(self, loopback):
+        """127.0.0.1 must pass the gate and reach the search function.
+        Uses raw ASGI peer IP via the ``loopback`` fixture — TestClient
+        would set ``request.client.host`` to ``"testclient"`` which
+        isn't on the loopback allowlist."""
+        fake = MagicMock(return_value={"ok": True, "results": []})
+        with patch("services.sentinel_search.search_sentinel2_scene", fake):
+            r = loopback.get("/api/sentinel2/search?lat=0&lng=0")
+        assert r.status_code == 200
+        assert fake.call_count == 1
+
+
+# Note: an earlier draft included a static dependency walker that
+# inspected the FastAPI route table to assert require_local_operator
+# was wired in. It was deleted because FastAPI's internal route
+# representation varies across minor versions — the walker was brittle
+# and the behavioral pair (anonymous → 403 with no upstream egress;
+# loopback → handler reached) gives stronger end-to-end evidence than
+# any structural check.