diff --git a/.gitea/workflows/diag.yml b/.gitea/workflows/diag.yml
new file mode 100644
index 0000000..31a4d5b
--- /dev/null
+++ b/.gitea/workflows/diag.yml
@@ -0,0 +1,40 @@
+name: Diag
+on:
+  push:
+    branches: [diag/auth-logout]
+jobs:
+  auth:
+    name: "Diag · auth logout-on-deploy"
+    runs-on: self-hosted
+    timeout-minutes: 5
+    env:
+      PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin
+    steps:
+      - name: Inspect JWT key, token TTL, redis persistence, container ages
+        run: |
+          set -eu
+          DEF="dev-jwt-key-CHANGE-THIS-IN-PRODUCTION-min32chars"
+          echo "=== api env: JWT key + access TTL + environment ==="
+          docker exec meezi-api sh -c '
+            echo "ASPNETCORE_ENVIRONMENT=${ASPNETCORE_ENVIRONMENT:-unset}"
+            echo "AccessTokenExpiryDays=${Jwt__AccessTokenExpiryDays:-unset(appsettings=30)}"
+            if [ "${Jwt__Key:-}" = "'"$DEF"'" ]; then echo "JWT_KEY=INSECURE_DEFAULT (stable)"; \
+            elif [ -z "${Jwt__Key:-}" ]; then echo "JWT_KEY=UNSET"; \
+            else echo "JWT_KEY=custom len=${#Jwt__Key} fp=$(printf %s "$Jwt__Key" | sha256sum | cut -c1-12)"; fi
+          ' || true
+          echo ""
+          echo "=== container ages + restart counts ==="
+          for c in meezi-api meezi-redis meezi-db; do
+            docker inspect "$c" --format "$c started={{.State.StartedAt}} restarts={{.RestartCount}}" 2>&1 || true
+          done
+          echo ""
+          echo "=== redis: persistence + refresh-token keys ==="
+          docker exec meezi-redis sh -c '
+            redis-cli DBSIZE
+            redis-cli CONFIG GET appendonly
+            echo "refresh-ish keys:"; redis-cli --scan --pattern "*refresh*" | head -5
+            echo "total refresh-ish:"; redis-cli --scan --pattern "*refresh*" | wc -l
+          ' || true
+          echo ""
+          echo "=== api logs: token validation failures / 401 (last 72h) ==="
+          docker logs meezi-api --since 72h 2>&1 | grep -iE "was not authenticated|SecurityToken|signature|IDX10|invalid token" | tail -15 || true