diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c1559e..c857b62 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,7 +16,15 @@ for 1.0.0 have something to be assembled from.
 
 ## Unreleased
 
-Nothing since 0.9.8.
+- The Updates page notices when the update helper on a host was installed for a
+  **different channel** than the page follows. It is declared in two places —
+  `lembas.env` and the systemd unit — and only the installer writes both, so
+  editing one by hand would have left the button deploying something other than
+  what the page named, with nothing anywhere saying so.
+- Fixed: release notes from a **signed** tag rendered the signature block.
+  `_notes_for` stripped the PGP header only, and which header appears depends on
+  `gpg.format` — this repository signs with SSH.
+- A `CHANGELOG.md`, kept from now on rather than assembled at release time.
 
 ## 0.9.8
 
diff --git a/deploy/install.sh b/deploy/install.sh
index 04f9b73..6a38c3a 100755
--- a/deploy/install.sh
+++ b/deploy/install.sh
@@ -175,7 +175,10 @@ if [[ "$INSTALL_UPDATE_HELPER" == "1" ]]; then
   done
   sudo systemctl daemon-reload
   sudo systemctl enable --now lembas-update.path
-  sudo touch "$UPDATE_MARKER"
+  # The channel goes *into* the marker, not just its existence. It is declared
+  # in two places -- the unit above and lembas.env -- and this is what lets the
+  # Updates page notice when somebody has edited one and not the other.
+  echo "$CHANNEL" | sudo tee "$UPDATE_MARKER" >/dev/null
   sudo chown "$SERVICE_USER:$SERVICE_USER" "$UPDATE_MARKER"
   echo "   installed. The web interface can now deploy the $CHANNEL channel and restart."
 else
diff --git a/src/lembas/services/updates.py b/src/lembas/services/updates.py
index 62de453..d664845 100644
--- a/src/lembas/services/updates.py
+++ b/src/lembas/services/updates.py
@@ -101,6 +101,19 @@ REQUEST_NAME = "update-requested"
 # Written by `install.sh` when the helper is installed. A marker rather than
 # asking systemd, because `systemctl is-enabled` means a subprocess on every
 # page render to answer a question that changes once.
+#
+# It carries the channel the helper was installed with, because that is declared
+# in **two** places -- here for the helper, and `lembas.env` for this process --
+# and `install.sh` writing both together is the only thing keeping them in step.
+# Edit one by hand and the page says `stable` while the button deploys `edge`,
+# with nothing anywhere disagreeing. Reading it back is what lets the page say
+# so. Empty on every host installed before this, which reads as "unknown" rather
+# than as a mismatch.
+#
+# Display only. The service account can write this file, so a compromised
+# process could lie about what the helper will do -- but not change it, because
+# the helper's own channel is baked into its unit under /etc, which this account
+# cannot touch. Lying about the channel is a much smaller thing than choosing it.
 MARKER_NAME = ".update-helper"
 
 # `%H` sha, `%s` subject, `%cI` date, split on a unit separator rather than a
@@ -159,9 +172,23 @@ class State:
     # before the version bump names a release nobody can identify afterwards.
     version_mismatch: str = ""
     helper: bool = False
+    # What the helper will actually deploy, when it said. Empty means it did not
+    # -- an older install -- and the page then says nothing rather than claiming
+    # agreement it cannot check.
+    helper_channel: str = ""
     requested: bool = False
     error: str = ""
 
+    @property
+    def channel_mismatch(self) -> bool:
+        """The page and the helper disagree about what would be deployed.
+
+        Only answerable when the helper said which channel it has. Somebody
+        edited one of the two places and not the other, and without this the
+        button would quietly deploy something other than what the page named.
+        """
+        return bool(self.helper_channel) and self.helper_channel != self.channel
+
     @property
     def is_git(self) -> bool:
         return bool(self.checkout)
@@ -239,6 +266,14 @@ def helper_installed() -> bool:
     return (settings.data_dir / MARKER_NAME).exists()
 
 
+def helper_channel() -> str:
+    """The channel the helper was installed with, or "" if it did not say."""
+    try:
+        return (settings.data_dir / MARKER_NAME).read_text(encoding="utf-8").strip()
+    except OSError:
+        return ""
+
+
 def request_path() -> Path:
     return settings.data_dir / REQUEST_NAME
 
@@ -345,6 +380,7 @@ def read(*, fetch: bool = False) -> State:
         "channel": channel,
         "branch": branch,
         "helper": helper_installed(),
+        "helper_channel": helper_channel(),
         "requested": pending(),
     }
     if root is None:
@@ -444,6 +480,7 @@ __all__ = [
     "channel_name",
     "checkout_dir",
     "clear_request",
+    "helper_channel",
     "helper_installed",
     "manual_command",
     "pending",
diff --git a/src/lembas/web/templates/admin/updates.html b/src/lembas/web/templates/admin/updates.html
index b040eac..619ef43 100644
--- a/src/lembas/web/templates/admin/updates.html
+++ b/src/lembas/web/templates/admin/updates.html
@@ -181,6 +181,25 @@
   </form>
 
   {% elif state.helper %}
+  {% if state.channel_mismatch %}
+  {#
+    The two declarations have drifted. Worth its own alert rather than a note:
+    the button would deploy something other than what this page has been naming
+    all the way down, and nothing else anywhere would say so.
+  #}
+  <div class="alert alert--error">
+    {{ icon("warning", "icon--sm") }}
+    <span>
+      This page follows <strong>{{ state.channel }}</strong> but the update
+      helper on this host was installed for
+      <strong>{{ state.helper_channel }}</strong> — so the button would deploy
+      the second, not the first. They are set in two places
+      (<code>lembas.env</code> and the systemd unit); re-run the installer with
+      <code>INSTALL_UPDATE_HELPER=1</code> and the channel you want, which
+      writes both.
+    </span>
+  </div>
+  {% endif %}
   <p class="card__lede">
     This host has the update helper installed, so the button below writes a
     request that a systemd unit picks up and runs as root. It always deploys the
diff --git a/tests/test_updates.py b/tests/test_updates.py
index aa3e1ad..8aeae0e 100644
--- a/tests/test_updates.py
+++ b/tests/test_updates.py
@@ -45,8 +45,8 @@ def clean():
     updates.clear_request()
 
 
-def _install_helper():
-    (settings.data_dir / updates.MARKER_NAME).touch()
+def _install_helper(channel: str = ""):
+    (settings.data_dir / updates.MARKER_NAME).write_text(channel)
 
 
 # --- Reading the state ----------------------------------------------------------
@@ -265,6 +265,33 @@ def test_an_unknown_channel_falls_back_to_stable(db, monkeypatch):
     assert updates.channel_name() == updates.CHANNEL_STABLE
 
 
+def test_a_helper_installed_for_another_channel_is_named(db, client, registered):
+    """The channel is declared in two places -- lembas.env and the systemd unit --
+    and only the installer writes both. Edit one by hand and the button deploys
+    something other than what the page has been naming all the way down."""
+    _install_helper("stable" if updates.channel_name() == "edge" else "edge")
+
+    state = updates.read()
+    assert state.channel_mismatch is True
+    assert "would deploy" in client.get("/admin/updates").text
+
+
+def test_a_helper_that_did_not_say_claims_no_disagreement(db):
+    """Every host installed before the marker carried a channel. Unknown is not
+    a mismatch, and claiming one would be a red alert on every existing host."""
+    _install_helper("")
+
+    assert updates.helper_channel() == ""
+    assert updates.read().channel_mismatch is False
+
+
+def test_a_matching_helper_says_nothing(db, client, registered):
+    _install_helper(updates.channel_name())
+
+    assert updates.read().channel_mismatch is False
+    assert "would deploy" not in client.get("/admin/updates").text
+
+
 # --- The page ---------------------------------------------------------------------
 def test_the_page_offers_nothing_without_the_helper(db, client, registered):
     page = client.get("/admin/updates").text