diff --git a/.github/workflows/deploy-dev.yml b/.github/workflows/deploy-dev.yml
index b0ff472b0..106738774 100644
--- a/.github/workflows/deploy-dev.yml
+++ b/.github/workflows/deploy-dev.yml
@@ -449,6 +449,36 @@ jobs:
           echo "::error title=Chat unavailable on the new backend::$POD has pg/status=$STATUS and pg/messages=$ROUTE (401 means mounted, 404 unmounted). Chat history fails until the pod restarts: kubectl rollout restart deploy/backend -n $NAMESPACE"
           exit 1
 
+      # A real hosted-agent turn through the live injection guard, for an agent named after a
+      # guard keyword — the class that 400'd a design partner every turn until #3285. Exit 3 =
+      # the guard blocked the turn, so fail the job and let the rollback step below fire; exit 2
+      # = inconclusive and exit 1 = kubectl/node failed, both warn only and never roll back.
+      # ~30s and 4 model turns, sharing the hosted cap with any hand run, so the
+      # concurrency:deploy-dev group (no cancel-in-progress) keeps deploys serial — a hand run
+      # during a deploy is the case to avoid. The script comes from the dispatched checkout, so
+      # it matches this release even while ops-runner is still rolling to the new image. The
+      # deploy service account needs pods/exec on litellm and ops-runner (it already execs the
+      # backend pod above). See docs/runbooks/guard-name-canary.md.
+      - name: Guard-name canary
+        id: canary
+        run: |
+          set -uo pipefail
+          KW=$(kubectl exec -i -n "$NAMESPACE" deploy/litellm -c litellm -- \
+                 /app/.venv/bin/python3 -I - < scripts/guard-keywords-dump.py) || KW=''
+          # Actions runs this under `bash -e`; `|| CODE=$?` keeps a non-zero
+          # exit from ending the step before it is read.
+          CODE=0
+          kubectl exec -i -n "$NAMESPACE" deploy/ops-runner -c ops-runner -- \
+            env NODE_PATH=/app/node_modules CANARY_RUN=1 CANARY_GUARD_KEYWORDS="$KW" \
+            node - < scripts/guard-name-canary.js || CODE=$?
+          if [ "$CODE" = 3 ]; then
+            echo "::error title=Guard-name canary blocked::the injection guard stopped a turn for an agent named after a guard keyword; see the check lines above"
+            exit 1
+          fi
+          if [ "$CODE" != 0 ]; then
+            echo "::warning title=Guard-name canary inconclusive::exit $CODE; read the check lines above"
+          fi
+
       # Record THIS release as rollout-verified (and, for dev, chat-verified), so the rollback
       # step below returns to a revision that actually passed verification — never merely "last
       # deployed". With auto-deploy, a deploy cancelled mid-verify by a newer push leaves an
@@ -484,7 +514,7 @@ jobs:
       # upgrade or a verify step failing (not bare failure()), so a pre-deploy failure (checkout,
       # auth, build/push) never demotes a healthy release.
       - name: Roll back on a failed deploy
-        if: ${{ failure() && (steps.helm.outcome == 'failure' || steps.rollout.outcome == 'failure' || steps.chat.outcome == 'failure') }}
+        if: ${{ failure() && (steps.helm.outcome == 'failure' || steps.rollout.outcome == 'failure' || steps.chat.outcome == 'failure' || steps.canary.outcome == 'failure') }}
         env:
           PRE: ${{ steps.prerev.outputs.prerev }}
         run: |
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a837d232a..61f313f77 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -120,6 +120,11 @@ jobs:
           node-version: 20
       - name: Filter regex regression test
         run: node --test scripts/changes-filter.test.mjs
+      # Guard the deploy-dev canary exit-code routing: the test reads the canary step
+      # and the rollback condition out of deploy-dev.yml, so a silent edit that turned a
+      # guard block (exit 3) into a green deploy, or dropped the rollback clause, fails CI.
+      - name: Deploy-dev canary wiring regression test
+        run: node --test scripts/guard-canary-wiring.test.mjs
 
   # Heavy jobs (backend, frontend, service tests) route to Latchkey runners on
   # a push to main when vars.LATCHKEY_HEAVY is 'on' AND the push touched a heavy
diff --git a/scripts/guard-canary-wiring.test.mjs b/scripts/guard-canary-wiring.test.mjs
new file mode 100644
index 000000000..a830cb4f2
--- /dev/null
+++ b/scripts/guard-canary-wiring.test.mjs
@@ -0,0 +1,63 @@
+// Regression test for the guard-name canary's exit-code routing in
+// .github/workflows/deploy-dev.yml. The canary step maps its script's exit code to a
+// deploy outcome: 3 = the live injection guard blocked the turn -> fail the step so the
+// rollback step fires; 1 (kubectl/node error) and 2 (inconclusive) = warn only, step
+// succeeds, no rollback; 0 = pass. A silent edit — 3 changed to 2, the sole `exit 1`
+// dropped, or the rollback clause removed — would turn a real guard block into a green
+// deploy, which is exactly the regression this guards. It reads the logic straight out of
+// the workflow (no duplication), the same approach as changes-filter.test.mjs.
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { dirname, join } from 'node:path';
+
+const ROOT = join(dirname(fileURLToPath(import.meta.url)), '..');
+const yml = readFileSync(join(ROOT, '.github/workflows/deploy-dev.yml'), 'utf8');
+
+// Extract one step's block: from its `- name: <name>` line to the next step's `- name:`.
+function stepBlock(text, name) {
+  const lines = text.split('\n');
+  const start = lines.findIndex((l) => l.trim() === `- name: ${name}`);
+  assert.ok(start >= 0, `step "${name}" not found in deploy-dev.yml`);
+  let end = lines.length;
+  for (let i = start + 1; i < lines.length; i += 1) {
+    if (/^\s*- name: /.test(lines[i])) { end = i; break; }
+  }
+  return lines.slice(start, end).join('\n');
+}
+
+const canary = stepBlock(yml, 'Guard-name canary');
+
+test('the canary step carries id: canary (the rollback condition references it)', () => {
+  assert.match(canary, /^\s*id:\s*canary\s*$/m);
+});
+
+test('only exit code 3 hard-fails the canary step', () => {
+  // 3 -> the step exits nonzero (fails) so failure() holds and rollback fires.
+  assert.match(canary, /if\s*\[\s*"\$CODE"\s*=\s*3\s*\]\s*;\s*then/);
+  // The CODE=3 branch is the ONLY path that exits nonzero. Any other nonzero exit
+  // would fail the step for an inconclusive/error code and trip a spurious rollback.
+  const nonzeroExits = (canary.match(/^\s*exit\s+[1-9][0-9]*\s*$/gm) || []).map((s) => s.trim());
+  assert.deepEqual(nonzeroExits, ['exit 1'],
+    'canary must have exactly one nonzero exit (inside the CODE=3 branch)');
+});
+
+test('exit codes 1 and 2 are warn-only (no rollback)', () => {
+  // A single `if [ "$CODE" != 0 ]` warn branch catches 1 and 2 without exiting nonzero.
+  assert.match(canary, /if\s*\[\s*"\$CODE"\s*!=\s*0\s*\]\s*;\s*then/);
+  assert.match(canary, /::warning title=Guard-name canary inconclusive/);
+});
+
+test('the rollback step fires on a canary failure', () => {
+  const rb = stepBlock(yml, 'Roll back on a failed deploy');
+  assert.match(rb, /failure\(\)\s*&&/);
+  assert.match(rb, /steps\.canary\.outcome\s*==\s*'failure'/);
+});
+
+test('a guard-blocked release is never recorded as rollout-verified', () => {
+  // The record step is `if: success()`, so a failed canary skips it and the next
+  // rollback returns to the last genuinely-verified revision, not this blocked one.
+  const rec = stepBlock(yml, 'Record this release as rollout-verified (rollback target)');
+  assert.match(rec, /^\s*if:\s*success\(\)\s*$/m);
+});