diff --git a/backend/fluksio/api/deps.py b/backend/fluksio/api/deps.py
index da2223c..069e539 100644
--- a/backend/fluksio/api/deps.py
+++ b/backend/fluksio/api/deps.py
@@ -18,9 +18,9 @@ from fluksio.core.db import engine
 from fluksio.flow import panels
 from fluksio.flow.artifacts import is_reference
 from fluksio.flow.controller import FlowController
-from fluksio.flow.dashboards import DashboardStore
+from fluksio.flow.dashboards import DashboardDef, DashboardStore
 from fluksio.flow.workers import PythonWorkerPool
-from fluksio.models import TokenPayload, User
+from fluksio.models import OAuthClient, TokenPayload, User
 
 reusable_oauth2 = OAuth2PasswordBearer(
     tokenUrl=f"{settings.API_V1_STR}/login/access-token"
@@ -80,6 +80,60 @@ def _panel_messages(panel_id: str, request: Request) -> set[str]:
     return panels.messages_for(panel_id, store)
 
 
+def _locked(defn: DashboardDef, live: dict[str, Any]) -> bool:
+    """Whether this dashboard is read-only right now.
+
+    Read the way the client reads it (``Dashboard/settings.tsx``): the bound
+    message if it is carrying something, and the stored value otherwise. Live,
+    because a lock a flow drives is the case the binding exists for — judging
+    it from the stored fallback alone would refuse every control on a
+    dashboard its flow has unlocked.
+    """
+    setting = defn.settings.get("locked")
+    if setting is None:
+        return False
+    value = live.get(setting.message) if setting.message else None
+    return (setting.value if value is None else value) is True
+
+
+def _panel_writable(panel_id: str, request: Request) -> set[str]:
+    """The messages this panel may publish to.
+
+    The same walk as the read allowlist, minus whatever a locked dashboard
+    contributes: ``locked`` is a dashboard saying it is there to be looked at,
+    and until this it stopped only the client drawing the control — the server
+    took the publish from a screen that asked anyway.
+
+    Not quite all of it: a querying chart publishes the request it reads by,
+    and a locked dashboard whose charts cannot ask goes blank rather than
+    read-only. That request is the exception ``panels.requests_of`` names.
+
+    Union, exactly as the allowlist itself is: a message one dashboard on this
+    panel displays and another controls stays writable, because the unlocked
+    one is what entitles the screen to it. Reads are untouched — read-only is
+    not blind, and a locked dashboard has to keep drawing live data.
+    """
+    store: DashboardStore | None = getattr(request.app.state, "dashboard_store", None)
+    if store is None:
+        return set()
+    defns = panels.dashboards_for(panel_id, store)
+    bound = sorted(
+        {s.message for d in defns if (s := d.settings.get("locked")) and s.message}
+    )
+    controller: FlowController | None = getattr(
+        request.app.state, "flow_controller", None
+    )
+    live = controller.state.get_present(bound) if bound and controller else {}
+    writable: set[str] = set()
+    for defn in defns:
+        writable |= (
+            panels.requests_of(defn)
+            if _locked(defn, live)
+            else panels.messages_of(defn)
+        )
+    return writable
+
+
 def _panel_digests(panel_id: str, request: Request) -> set[str]:
     """The artifacts this panel's messages are pointing at right now.
 
@@ -116,7 +170,10 @@ def _panel_may(payload: dict[str, Any], request: Request) -> None:
     asks for its window by publishing a request, which is why that request
     counts as one of its widget's messages. Bounded to those, though: a screen
     on a wall has no business reaching a message no tile on it draws, and the
-    catalogue behind ``GET /messages/`` is the whole namespace at once.
+    catalogue behind ``GET /messages/`` is the whole namespace at once. A
+    dashboard that says it is locked is bounded further still — it entitles a
+    panel to read every message it names and to publish to none of them but
+    the requests its own charts ask by.
 
     # ponytail: the panel file and the published dashboards are re-read per
     # request. Cache them behind the store's version if this shows up in a
@@ -146,13 +203,16 @@ def _panel_may(payload: dict[str, Any], request: Request) -> None:
         # value in. Percent-decoded, because a message name is a path segment
         # here and the client encodes it as one.
         rest = unquote(path[len(f"{api}/messages/") :])
+        scope = _panel_messages
         if method == "GET" and rest.endswith(_HISTORY):
             name = rest[: -len(_HISTORY)]
         elif method == "POST":
             name = rest
+            # A locked dashboard entitles the panel to nothing it can publish.
+            scope = _panel_writable
         else:
             name = ""
-        allowed = bool(name) and name in _panel_messages(panel.id, request)
+        allowed = bool(name) and name in scope(panel.id, request)
     elif method == "GET" and path.startswith(f"{api}/artifacts/"):
         # The bytes behind a media message a tile on this panel is drawing.
         # Scoped to what those messages hold *now*, which is exactly what a
@@ -182,6 +242,10 @@ def decode_token(token: str, request: Request | None = None) -> dict[str, Any]:
     refuses it outright, so the only door it fits is the one ``_panel_may``
     guards.
 
+    An agent's token is held to one thing more: the client it names has to
+    still be registered, which is what makes revoking an agent take effect now
+    rather than whenever its stateless token happens to expire.
+
     The last branch is the seam a hosted deployment widens: a portal this
     instance was enrolled with signs tokens with a key pinned at
     enrolment, and they name the portal account holding them, which resolves
@@ -209,9 +273,38 @@ def decode_token(token: str, request: Request | None = None) -> dict[str, Any]:
             raise InvalidTokenError("a panel token must name its panel")
         return _gate_panel(panel_token, request)
     try:
-        return security.decode_oauth_token(token)
+        agent = security.decode_oauth_token(token)
     except InvalidTokenError:
         return _gate_panel(cloud_config.decode_portal_token(token), request)
+    return _gate_agent(agent)
+
+
+def oauth_client_lives(client_id: str) -> bool:
+    """Is the agent a token names still a registered client? Blocking.
+
+    An MCP access token is a stateless JWT good until it expires, so deleting
+    the client row revoked nothing that had already been handed out. The
+    client id is a claim the token has always carried, so this holds the ones
+    already in circulation just as well as the next one minted.
+
+    One primary-key read per agent request, against a table with a row per
+    registered agent. The request it gates goes on to look its user up the
+    same way, and the panel gate next door re-reads the panels file and every
+    published dashboard from disk, so this is the cheapest check in here.
+    """
+    try:
+        key = uuid.UUID(client_id)
+    except ValueError:
+        return False
+    with Session(engine) as session:
+        return session.get(OAuthClient, key) is not None
+
+
+def _gate_agent(payload: dict[str, Any]) -> dict[str, Any]:
+    """Refuse a token whose agent has been revoked."""
+    if not oauth_client_lives(str(payload.get("client_id") or "")):
+        raise InvalidTokenError("this agent's registration was withdrawn")
+    return payload
 
 
 def _gate_panel(payload: dict[str, Any], request: Request | None) -> dict[str, Any]:
diff --git a/backend/fluksio/api/routes/oauth.py b/backend/fluksio/api/routes/oauth.py
index ce77e21..f69f512 100644
--- a/backend/fluksio/api/routes/oauth.py
+++ b/backend/fluksio/api/routes/oauth.py
@@ -555,9 +555,11 @@ def revoke_client(client_id: uuid.UUID, session: SessionDep) -> Any:
     """Withdraw one agent's access, leaving every other agent alone.
 
     Deleting the client cascades to its codes and refresh tokens, so it can
-    get nothing new and cannot come back without registering again. An access
-    token already in its hands keeps working until it expires
-    (``MCP_TOKEN_EXPIRE_MINUTES``) — those are stateless by design.
+    get nothing new and cannot come back without registering again. The access
+    token already in its hands stops working too, even though it is a
+    stateless JWT nobody can reach into: every door that takes one looks the
+    client up first (``api.deps.oauth_client_lives``), so the row deleted here
+    is the whole of the revocation.
     """
     client = session.get(OAuthClient, client_id)
     if client is None:
diff --git a/backend/fluksio/flow/panels.py b/backend/fluksio/flow/panels.py
index 9c999c5..dc3bc19 100644
--- a/backend/fluksio/flow/panels.py
+++ b/backend/fluksio/flow/panels.py
@@ -18,7 +18,7 @@ from pathlib import Path
 from pydantic import BaseModel, Field, field_validator
 
 from fluksio.core.config import settings
-from fluksio.flow.dashboards import DashboardNotFound, DashboardStore
+from fluksio.flow.dashboards import DashboardDef, DashboardNotFound, DashboardStore
 from fluksio.flow.schemas import _validate_name
 
 
@@ -101,29 +101,62 @@ def find(panel_id: str) -> PanelDef | None:
     return None
 
 
-def messages_for(panel_id: str, store: DashboardStore) -> set[str]:
-    """Every message this panel's dashboards read or write.
+def dashboards_for(panel_id: str, store: DashboardStore) -> list[DashboardDef]:
+    """The published documents this panel shows, in rail order.
 
-    What a screen is entitled to see, as its own dashboards define it. Read
-    from the published documents, since that is what a panel draws, and empty
-    for a panel that is gone — which is the same answer as "nothing".
+    Published, since that is what a panel draws. A name that no longer
+    resolves is a dashboard someone deleted and is skipped, and a panel that
+    is gone shows nothing.
+
+    Handed back whole rather than walked here, because what a panel may do
+    with a message depends on the document it came from — a dashboard that
+    says it is locked entitles a screen to read it and not to touch it.
+    """
+    panel = find(panel_id)
+    if panel is None:
+        return []
+    found: list[DashboardDef] = []
+    for name in panel.dashboards:
+        try:
+            found.append(store.read(name))
+        except DashboardNotFound:
+            continue
+    return found
+
+
+def messages_of(defn: DashboardDef) -> set[str]:
+    """Every message one dashboard reads or writes.
 
     A dashboard's own bound settings count, not only its widgets': the theme a
     panel is driven to is a message no tile on it draws, and a wall panel
     refused its own theme message is the one surface the setting exists for.
     """
-    panel = find(panel_id)
-    if panel is None:
-        return set()
-    names: set[str] = set()
-    for dashboard in panel.dashboards:
-        try:
-            defn = store.read(dashboard)
-        except DashboardNotFound:
-            continue
-        names.update(defn.setting_messages)
-        for widget in defn.widgets:
-            names.update(widget.messages)
-            if widget.target:
-                names.add(widget.target)
+    names = set(defn.setting_messages)
+    for widget in defn.widgets:
+        names.update(widget.messages)
+        if widget.target:
+            names.add(widget.target)
     return names
+
+
+def requests_of(defn: DashboardDef) -> set[str]:
+    """The publishes this dashboard makes in order to read.
+
+    A querying chart asks a flow for the series it draws by publishing a
+    request, so that publish is how the tile reads rather than something
+    anyone touched. Every other message a dashboard sends comes from a
+    control, which is what marking it read-only turns off — so this is what a
+    locked dashboard is still entitled to send.
+    """
+    return {w.target for w in defn.widgets if w.type == "chart" and w.target}
+
+
+def messages_for(panel_id: str, store: DashboardStore) -> set[str]:
+    """Every message this panel's dashboards read or write.
+
+    What a screen is entitled to see, as its own dashboards define it, and
+    empty for a panel that is gone — which is the same answer as "nothing".
+    """
+    return {
+        name for defn in dashboards_for(panel_id, store) for name in messages_of(defn)
+    }
diff --git a/backend/fluksio/mcp/http.py b/backend/fluksio/mcp/http.py
index 4a3800e..6f77fc0 100644
--- a/backend/fluksio/mcp/http.py
+++ b/backend/fluksio/mcp/http.py
@@ -13,12 +13,14 @@ from urllib.parse import urlparse
 
 import httpx
 import jwt
+from fastapi.concurrency import run_in_threadpool
 from mcp.server.auth.provider import AccessToken
 from mcp.server.auth.settings import AuthSettings
 from mcp.server.transport_security import TransportSecuritySettings
 from pydantic import AnyHttpUrl
 from starlette.applications import Starlette
 
+from fluksio.api.deps import oauth_client_lives
 from fluksio.core import security
 from fluksio.core.config import settings
 from fluksio.mcp import server
@@ -30,11 +32,18 @@ _INTERNAL_BASE = "http://fluksio-mcp.internal"
 
 
 class _JWTVerifier:
-    """Accept only tokens minted for the MCP channel.
+    """Accept only tokens minted for the MCP channel, by agents still registered.
 
     A perfectly valid browser token is refused: it was issued for a person's
     session, and honouring it here would make agent traffic indistinguishable
     from theirs.
+
+    The client row is looked up because the token itself cannot be withdrawn:
+    it is stateless and good until ``MCP_TOKEN_EXPIRE_MINUTES`` runs out, so
+    the registration it names is the thing revoking an agent actually removes.
+    Refusing at the door rather than leaving it to the API the tools call means
+    a revoked agent gets the 401 that sends it back to authorize, instead of a
+    tool listing that works and a tool call that does not.
     """
 
     async def verify_token(self, token: str) -> AccessToken | None:
@@ -46,9 +55,17 @@ class _JWTVerifier:
         if payload.get("mcp") is not True:
             logger.debug("MCP token rejected: not an MCP-channel token")
             return None
+        client_id = str(payload.get("client_id", ""))
+        # Off the event loop: the lookup is SQLite, like every other read this
+        # process makes, and the session it opens is blocking.
+        if not await run_in_threadpool(oauth_client_lives, client_id):
+            logger.debug(
+                "MCP token rejected: agent %s is no longer registered", client_id
+            )
+            return None
         return AccessToken(
             token=token,
-            client_id=str(payload.get("client_id", "")),
+            client_id=client_id,
             scopes=[security.MCP_SCOPE],
             subject=str(payload.get("sub", "")),
         )
diff --git a/backend/tests/api/routes/test_oauth.py b/backend/tests/api/routes/test_oauth.py
index c6dcdaf..100e05c 100644
--- a/backend/tests/api/routes/test_oauth.py
+++ b/backend/tests/api/routes/test_oauth.py
@@ -270,6 +270,17 @@ def test_one_agent_can_be_revoked_without_touching_the_others(
     assert revoked.status_code == 200, revoked.text
     assert all(c["id"] != client_id for c in listed())
 
+    # And the access token already in its hands stops working, rather than
+    # outliving the revocation by up to MCP_TOKEN_EXPIRE_MINUTES: the token is
+    # stateless, so the client row it names is what withdrawing it removes.
+    assert (
+        client.post(
+            f"{settings.API_V1_STR}/login/test-token",
+            headers={"Authorization": f"Bearer {tokens['access_token']}"},
+        ).status_code
+        == 401
+    )
+
     # Its refresh token went with it, so it cannot mint itself a new one.
     refreshed = client.post(
         f"{PREFIX}/token",
diff --git a/backend/tests/api/routes/test_panels.py b/backend/tests/api/routes/test_panels.py
index 0efdda0..fd29d89 100644
--- a/backend/tests/api/routes/test_panels.py
+++ b/backend/tests/api/routes/test_panels.py
@@ -345,6 +345,88 @@ def test_a_panel_speaks_only_its_own_widgets_messages(
     )
 
 
+def _publish_settings(
+    client: TestClient, headers: dict[str, str], name: str, settings_: dict
+) -> None:
+    """Give a published dashboard these settings and publish it again."""
+    saved = client.get(f"{DASHBOARDS}/{name}?draft=true", headers=headers).json()
+    saved["settings"] = settings_
+    written = client.put(f"{DASHBOARDS}/{name}", headers=headers, json=saved)
+    assert written.status_code == 200, written.text
+    published = client.post(
+        f"{DASHBOARDS}/{name}/publish",
+        headers=headers,
+        json={"version": written.json()["version"]},
+    )
+    assert published.status_code == 200, published.text
+
+
+def test_a_locked_dashboard_entitles_a_panel_to_read_and_not_to_publish(
+    client: TestClient, superuser_token_headers: dict[str, str]
+) -> None:
+    """`locked` bounds what a screen may send, not what it may draw.
+
+    It used to bound neither: the client stopped offering the control and the
+    server took the publish from anything that asked anyway.
+
+    Unions like the allowlist itself, which is what the second dashboard here
+    is for — a message a locked dashboard shows and an unlocked one controls
+    stays writable, because the unlocked one is what entitles the panel to it.
+    """
+    _dashboard_with(client, superuser_token_headers, "panel_locked", PANEL_WIDGETS)
+    _publish_settings(
+        client, superuser_token_headers, "panel_locked", {"locked": {"value": True}}
+    )
+    _dashboard_with(
+        client,
+        superuser_token_headers,
+        "panel_open",
+        [{"id": "w_button", "type": "button", "config": {"target": "demo.button"}}],
+    )
+    _panels(
+        client,
+        superuser_token_headers,
+        {"panels": [{"id": "foyer", "dashboards": ["panel_locked", "panel_open"]}]},
+    )
+    panel_headers = _pair(client, superuser_token_headers, "foyer")
+    messages = f"{settings.API_V1_STR}/messages"
+
+    # Only the locked dashboard names it, so there is nothing left to send it.
+    assert (
+        client.post(
+            f"{messages}/demo.slider", headers=panel_headers, json={"value": 1}
+        ).status_code
+        == 403
+    )
+    # 404, not 403: past the gate, and refused by an engine that knows no such
+    # message. The unlocked dashboard binds this one too.
+    assert (
+        client.post(
+            f"{messages}/demo.button", headers=panel_headers, json={"value": 1}
+        ).status_code
+        == 404
+    )
+    # A querying chart's request survives the lock: publishing it is how that
+    # tile *reads*, and a locked dashboard whose charts cannot ask goes blank
+    # rather than read-only.
+    assert (
+        client.post(
+            f"{messages}/demo.query_request",
+            headers=panel_headers,
+            json={"value": {"range_s": 3600, "interval_s": 60}},
+        ).status_code
+        == 404
+    )
+    # And what the locked dashboard draws is still readable — read-only is not
+    # blind, and a wall panel showing stale numbers is the failure to avoid.
+    assert (
+        client.get(
+            f"{messages}/demo.temperature/history", headers=panel_headers
+        ).status_code
+        == 200
+    )
+
+
 def test_a_panel_may_read_its_dashboards_own_settings(
     client: TestClient, superuser_token_headers: dict[str, str]
 ) -> None:
@@ -854,8 +936,9 @@ def test_a_socket_pushes_only_the_frames_it_was_asked_for(tmp_path) -> None:
 
     store = ArtifactStore(tmp_path / "artifacts")
     store.volatile = VolatileStore(tmp_path / "ring", limit_bytes=1_000_000)
-    frame = store.put([b"\x89PNG..."], name="f.png", media_type="image/png",
-                      volatile=True)
+    frame = store.put(
+        [b"\x89PNG..."], name="f.png", media_type="image/png", volatile=True
+    )
     kept = store.put([b"checkpoint"], name="w.pt")
 
     asking = orjson.dumps({"type": "media", "names": ["cam.frame", "other.frame"]})
diff --git a/backend/tests/mcp/test_mcp_http.py b/backend/tests/mcp/test_mcp_http.py
index da04760..8a6f89a 100644
--- a/backend/tests/mcp/test_mcp_http.py
+++ b/backend/tests/mcp/test_mcp_http.py
@@ -2,25 +2,38 @@
 
 import asyncio
 import uuid
-from collections.abc import Awaitable, Callable
+from collections.abc import Awaitable, Callable, Generator
 from datetime import timedelta
 from typing import Any
 
 import httpx
 import pytest
 from fastapi.testclient import TestClient
+from sqlmodel import Session
 
 from fluksio.core import security
 from fluksio.core.config import settings
 from fluksio.main import app
+from fluksio.models import OAuthClient
 
 MCP_HEADERS = {"Accept": "application/json, text/event-stream"}
 
 
-def mcp_token(user_id: uuid.UUID) -> str:
-    return security.create_oauth_access_token(
-        user_id, uuid.uuid4(), timedelta(minutes=5)
-    )
+def mcp_token(user_id: uuid.UUID, client_id: uuid.UUID) -> str:
+    return security.create_oauth_access_token(user_id, client_id, timedelta(minutes=5))
+
+
+@pytest.fixture
+def agent(db: Session) -> Generator[uuid.UUID, None, None]:
+    """A registered agent, because a token naming one that is gone is refused."""
+    row = OAuthClient(client_name="Test agent", redirect_uris=[])
+    db.add(row)
+    db.commit()
+    yield row.id
+    left = db.get(OAuthClient, row.id)
+    if left is not None:
+        db.delete(left)
+        db.commit()
 
 
 @pytest.fixture
@@ -96,12 +109,15 @@ def test_a_browser_token_is_not_an_agent_token(
 
 
 def test_an_agent_can_list_and_call_tools(
-    over_mcp, client: TestClient, superuser_token_headers: dict[str, str]
+    over_mcp,
+    client: TestClient,
+    superuser_token_headers: dict[str, str],
+    agent: uuid.UUID,
 ) -> None:
     me = client.get(
         f"{settings.API_V1_STR}/users/me", headers=superuser_token_headers
     ).json()
-    token = mcp_token(uuid.UUID(me["id"]))
+    token = mcp_token(uuid.UUID(me["id"]), agent)
 
     async def block(http: httpx.AsyncClient) -> tuple[Any, Any]:
         listed = await http.post("/mcp", **rpc(token, "tools/list"))
@@ -121,3 +137,36 @@ def test_an_agent_can_list_and_call_tools(
     assert called.status_code == 200
     assert "error" not in called.json()
     assert called.json()["result"]["isError"] is False
+
+
+def test_revoking_an_agent_stops_the_token_it_already_holds(
+    over_mcp,
+    client: TestClient,
+    db: Session,
+    superuser_token_headers: dict[str, str],
+    agent: uuid.UUID,
+) -> None:
+    """Withdrawing an agent has to bite now, not whenever its token expires.
+
+    An access token is a stateless JWT valid for its whole life, so the
+    registration it names is the only thing deleting a client takes away.
+
+    Both calls share one block because the session manager runs once.
+    """
+    me = client.get(
+        f"{settings.API_V1_STR}/users/me", headers=superuser_token_headers
+    ).json()
+    token = mcp_token(uuid.UUID(me["id"]), agent)
+
+    async def block(http: httpx.AsyncClient) -> tuple[Any, Any]:
+        before = await http.post("/mcp", **rpc(token, "tools/list"))
+        row = db.get(OAuthClient, agent)
+        assert row is not None
+        db.delete(row)
+        db.commit()
+        after = await http.post("/mcp", **rpc(token, "tools/list"))
+        return before, after
+
+    before, after = over_mcp(block)
+    assert before.status_code == 200
+    assert after.status_code == 401
diff --git a/frontend/src/components/Dashboard/publish.tsx b/frontend/src/components/Dashboard/publish.tsx
index 4e26ae0..e389f80 100644
--- a/frontend/src/components/Dashboard/publish.tsx
+++ b/frontend/src/components/Dashboard/publish.tsx
@@ -43,10 +43,10 @@ function confirms(live: unknown, sent: unknown): boolean {
  * disabled — a dashboard that silently swallows a press looks broken rather
  * than locked.
  *
- * ponytail: this is a read-only surface, not an authorisation boundary. The
- * server still takes a publish from a panel credential whose dashboard says
- * locked, because the credential's own allowlist is what bounds it. Making it
- * a real lock means carrying the flag into `_panel_may`.
+ * Not the boundary, though — the affordance. A panel credential is bounded by
+ * the same flag on the server (`api/deps.py`, `_panel_writable`), which is
+ * what refuses a publish from a screen that asks anyway; this is what keeps a
+ * control from looking pressable when it is not.
  *
  * Its own module rather than `widgets.tsx`, which every widget file is
  * imported *by*: a control drawn in a file of its own can only reach this