diff --git a/README.md b/README.md
index 5fc43dc..f21be96 100644
--- a/README.md
+++ b/README.md
@@ -65,7 +65,26 @@ sudo apt-get update && sudo apt-get install stoke
 
 Upgrades then arrive through regular `apt-get upgrade`. `install-apt.sh` performs all of the above, adding the NodeSource repository only when no already-configured apt source offers a new-enough nodejs.
 
-Note: apt releases that verify OpenPGP with `sqv` (Debian 13+, apt >= 2.9) may reject signatures produced by affected Forgejo versions. `install-apt.sh` permits its `[trusted=yes]` compatibility fallback only when apt reports an explicit signature failure. Authentication, network, and all other update failures are fatal and leave the `signed-by=` source unchanged, so a transient error cannot silently disable verification.
+Note: apt releases that verify OpenPGP with `sqv` (Debian 13+, apt >= 2.9)
+may reject signatures produced by affected Forgejo versions. By default,
+`install-apt.sh` refuses that signature failure and removes the Forge source;
+authentication, network, and all other update failures are also fatal and never
+disable verification.
+
+If the installer reports the known `sqv` parsing failure and you deliberately
+accept HTTPS-only integrity without OpenPGP verification, opt in on a second
+run:
+
+```bash
+export STOKE_ALLOW_UNVERIFIED_APT=1
+sudo --preserve-env=FORGE_USER,FORGE_TOKEN,STOKE_ALLOW_UNVERIFIED_APT \
+  bash /tmp/stoke-install-apt.sh
+unset STOKE_ALLOW_UNVERIFIED_APT
+```
+
+This exact opt-in is the only path in the installer that writes a
+`[trusted=yes]` source. The installer prints the security trade-off again when
+it takes that path.
 
 As a fallback, each release also has the `.deb` attached for direct install: `sudo dpkg -i stoke_<version>_all.deb`.
 
diff --git a/changelog.d/1.md b/changelog.d/1.md
index 02d4760..2e9b255 100644
--- a/changelog.d/1.md
+++ b/changelog.d/1.md
@@ -1 +1 @@
-- Private apt installs now keep credentials out of source URLs and retain signature verification after non-signature update failures. (#1).
+- Private apt installs keep credentials out of source URLs, refuse unverifiable registries by default, and require an explicit HTTPS-only opt-in to disable signature checks. (#1).
diff --git a/scripts/install-apt.sh b/scripts/install-apt.sh
index 15ba9cb..867c3be 100755
--- a/scripts/install-apt.sh
+++ b/scripts/install-apt.sh
@@ -9,6 +9,7 @@
 # Usage:
 #   ./scripts/install-apt.sh
 #   FORGE_URL=... OWNER=... ./scripts/install-apt.sh   # non-default instance
+#   STOKE_ALLOW_UNVERIFIED_APT=1 ./scripts/install-apt.sh  # explicit HTTPS-only opt-in
 #
 # Run as root or as a user with sudo.
 
@@ -20,6 +21,7 @@ DISTRIBUTION="${DISTRIBUTION:-stable}"
 COMPONENT="${COMPONENT:-main}"
 FORGE_USER="${FORGE_USER:-}"
 FORGE_TOKEN="${FORGE_TOKEN:-}"
+ALLOW_UNVERIFIED="${STOKE_ALLOW_UNVERIFIED_APT:-}"
 # Where apt configuration lives; overridable so tests can run against a
 # throwaway directory instead of the real /etc/apt.
 APT_ETC="${STOKE_APT_ETC:-/etc/apt}"
@@ -34,6 +36,11 @@ if { [ -n "$FORGE_USER" ] && [ -z "$FORGE_TOKEN" ]; } \
   exit 1
 fi
 
+if [ -n "$ALLOW_UNVERIFIED" ] && [ "$ALLOW_UNVERIFIED" != "1" ]; then
+  echo "error: STOKE_ALLOW_UNVERIFIED_APT must be unset or exactly 1" >&2
+  exit 1
+fi
+
 SUDO=""
 if [ "$(id -u)" -ne 0 ]; then
   command -v sudo >/dev/null 2>&1 || { echo "error: run as root or install sudo" >&2; exit 1; }
@@ -127,9 +134,9 @@ fi
 # is not the key algorithm, because the registry serves an RSA-2048 signing
 # key (`gpg --list-packets` on repository.key reports `algo 1` with a
 # 2048-bit pkey[0]). Try the properly signed source first so this heals
-# automatically once the forge is fixed. Only that signature-error
-# class permits the compatibility fallback; auth, network, and other failures
-# must leave verification enabled and retain apt's original diagnostic.
+# automatically once the forge is fixed. Only that signature-error class, plus
+# the user's exact opt-in, permits an unverified source; auth, network, and
+# other failures must leave verification enabled and retain apt's diagnostic.
 if update_output="$(update_only_source "$LIST" 2>&1)"; then
   printf '%s\n' "$update_output"
 else
@@ -140,11 +147,21 @@ else
     printf '%s\n' "$update_output" >&2
     exit "$update_status"
   fi
-  echo
-  echo "WARNING: signature verification failed (known Forgejo registry issue" >&2
-  echo "with sqv-based apt). Falling back to [trusted=yes]; transport" >&2
-  echo "security is provided by HTTPS to $FORGE_URL." >&2
-  echo
+  if [ "$ALLOW_UNVERIFIED" != "1" ]; then
+    $SUDO rm -f "$LIST"
+    echo "error: apt could not verify the Forgejo registry signature." >&2
+    echo "On sqv-based apt, the known cause is that sqv-based apt cannot parse" >&2
+    echo "the Forgejo registry signature, although gpgv-based apt accepts it." >&2
+    echo "No apt source was left behind." >&2
+    echo "If you knowingly accept HTTPS-only integrity, re-run with" >&2
+    echo "STOKE_ALLOW_UNVERIFIED_APT=1 to disable OpenPGP verification." >&2
+    exit "$update_status"
+  fi
+  echo >&2
+  echo "WARNING: OpenPGP signature verification is disabled for the Forgejo" >&2
+  echo "registry at $FORGE_URL. You explicitly accepted HTTPS-only integrity" >&2
+  echo "by setting STOKE_ALLOW_UNVERIFIED_APT=1." >&2
+  echo >&2
   echo "deb [trusted=yes] $FORGE_URL/api/packages/$OWNER/debian $DISTRIBUTION $COMPONENT" \
     | $SUDO tee "$LIST" >/dev/null
   $SUDO chmod 0644 "$LIST"
diff --git a/test/install-apt.test.js b/test/install-apt.test.js
index 93a5b4e..fdcae15 100644
--- a/test/install-apt.test.js
+++ b/test/install-apt.test.js
@@ -15,12 +15,13 @@ const SCRIPT = path.join(__dirname, '..', 'scripts', 'install-apt.sh');
 //   releaseStatus      HTTP status curl reports for the registry Release file
 //   sourceUpdateError  stderr and exit 100 for the first signed stoke update
 //   forgeUser/token    private-registry credentials
+//   allowUnverified    explicit HTTPS-only integrity opt-in
 // The apt-cache stub localizes the "Candidate:" label unless LC_ALL=C is set,
 // so every scenario doubles as a regression test for locale-safe parsing.
 const cleanups = [];
 process.on('exit', () => { for (const dir of cleanups) fs.rmSync(dir, { recursive: true, force: true }); });
 
-function runScenario({ candInitial, candAfterUpdate, candAfterNodesource, preexistingNodesourceList, releaseStatus, sourceUpdateError, forgeUser, forgeToken }) {
+function runScenario({ candInitial, candAfterUpdate, candAfterNodesource, preexistingNodesourceList, releaseStatus, sourceUpdateError, forgeUser, forgeToken, allowUnverified }) {
   const root = fs.mkdtempSync(path.join(os.tmpdir(), 'stoke-apt-test-'));
   cleanups.push(root);
   const bin = path.join(root, 'bin');
@@ -101,6 +102,7 @@ function runScenario({ candInitial, candAfterUpdate, candAfterNodesource, preexi
       SOURCE_UPDATE_ERROR: sourceUpdateError || '',
       FORGE_USER: forgeUser || '',
       FORGE_TOKEN: forgeToken || '',
+      STOKE_ALLOW_UNVERIFIED_APT: allowUnverified || '',
       LC_ALL: 'es_ES.UTF-8', // localized environment; the script must force C
     },
   });
@@ -194,16 +196,42 @@ test('registry Release file present: proceeds with the install', () => {
   assert.match(s.aptGetLog, /install -y stoke/);
 });
 
-test('signature verification failure alone may use the trusted compatibility fallback', () => {
+test('signature verification failure refuses by default and removes the forge source', () => {
   const s = runScenario({
     candInitial: '22.23.1-1nodesource1',
     sourceUpdateError: 'W: GPG error: signatures could not be verified: NO_PUBKEY DEADBEEF\nE: The repository is not signed.',
   });
+  assert.notEqual(s.res.status, 0);
+  assert.equal(s.forgeList, null);
+  assert.match(s.res.stderr, /sqv-based apt cannot parse\s+the Forgejo registry signature/);
+  assert.match(s.res.stderr, /STOKE_ALLOW_UNVERIFIED_APT=1/);
+  assert.doesNotMatch(s.aptGetLog, /install -y stoke/);
+});
+
+test('exact opt-in permits an HTTPS-only forge source after signature failure', () => {
+  const s = runScenario({
+    candInitial: '22.23.1-1nodesource1',
+    sourceUpdateError: 'W: GPG error: signatures could not be verified: NO_PUBKEY DEADBEEF\nE: The repository is not signed.',
+    allowUnverified: '1',
+  });
   assert.equal(s.res.status, 0, s.res.stderr);
   assert.match(s.forgeList, /\[trusted=yes\]/);
+  assert.match(s.res.stderr, /OpenPGP signature verification is disabled/);
+  assert.match(s.res.stderr, /HTTPS-only integrity/);
   assert.match(s.aptGetLog, /install -y stoke/);
 });
 
+test('unrecognized opt-in value is rejected before configuring apt', () => {
+  const s = runScenario({
+    candInitial: '22.23.1-1nodesource1',
+    allowUnverified: 'yes',
+  });
+  assert.notEqual(s.res.status, 0);
+  assert.match(s.res.stderr, /STOKE_ALLOW_UNVERIFIED_APT must be unset or exactly 1/);
+  assert.equal(s.forgeList, null);
+  assert.equal(s.aptGetLog, '');
+});
+
 test('network update failure stays fatal and never disables signature verification', () => {
   const failure = 'Temporary failure resolving forgejo.heavyduty.builders';
   const s = runScenario({