docs/ARCHITECTURE.md

@@ -888,6 +888,19 @@ addition.
 - Health probes are unauthenticated `GET /healthz` (process liveness) and
   `GET /readyz` (Postgres reachable, migrations applied, gRPC listener
   bound). Probes are excluded from anti-replay and rate limiting.
+- **Collection (dev, production mirror).** The long-lived dev environment
+  (`tools/dev-deploy/`) runs a full metrics + logs + traces stack on its
+  internal network with no host ports: Prometheus scrapes the backend
+  (`:9100`) and gateway (`:9191`) endpoints plus `node-exporter` and
+  cAdvisor; Tempo ingests OTLP traces from backend and gateway; Loki
+  stores container logs shipped by promtail (Docker service-discovery on
+  the `galaxy.stack=dev-deploy` label). Grafana (provisioned datasources
+  + dashboards) and the Mailpit capture UI are reached only through the
+  operator console's single `/_gm` Basic Auth gate (§14.1) — at
+  `/_gm/grafana/` and `/_gm/mailpit/` — so one password covers the
+  console and both UIs. Retention is tuned small (Prometheus 15d, Loki
+  7d, Tempo 3d). The same compose fragment is meant to back production.
+  See `tools/dev-deploy/monitoring/README.md`.
 
 ## 18. CI and Environments
 

docs/FUNCTIONAL.md

@@ -1182,7 +1182,10 @@ The console landing page is a dashboard that summarises operational
 health: whether the backend is ready and the database reachable, how many
 game runtimes sit in each state, and the depth of the mail and
 notification queues. It is a read-only point-in-time view for quick
-triage, not a metrics history.
+triage, not a metrics history. The console nav also links to Grafana
+(metrics, logs and traces) and the Mailpit capture UI, which the
+deployment serves under the same `/_gm` Basic Auth gate — one sign-in
+covers the console and both UIs.
 
 ### 10.3 Admin account management
 

docs/FUNCTIONAL_ru.md

@@ -1218,7 +1218,9 @@ admin-API, либо через серверно-рендеримую веб-ко
 здоровье: готов ли backend и доступна ли БД, сколько игровых рантаймов
 в каждом состоянии, какова глубина очередей почты и уведомлений. Это
 read-only-срез на текущий момент для быстрой диагностики, не история
-метрик.
+метрик. Навигация консоли также ведёт в Grafana (метрики, логи и
+трейсы) и в UI захвата почты Mailpit, которые деплой отдаёт под тем же
+шлюзом Basic Auth `/_gm` — один вход покрывает консоль и оба UI.
 
 ### 10.3 Управление admin-аккаунтами
 

tools/dev-deploy/README.md

@@ -148,6 +148,38 @@ With none set the stack only captures mail (the compose relay-match
 defaults to a non-routable address), so it can never email third
 parties.
 
+The capture UI is exposed through the operator console's `/_gm` gate at
+[`/_gm/mailpit/`](https://galaxy.lan/_gm/mailpit/) — one Basic Auth for
+the console, Grafana and Mailpit (see **Observability**). It shows
+**every** message the backend sent, relayed or not, so you can read any
+account's OTP regardless of the relay-match. For multi-account testing:
+register several `you+tag@gmail.com` aliases and widen the match to a
+regex such as `^you(\+[^@]+)?@gmail\.com$` (Gmail folds every `+tag`
+into one inbox), or just read the codes in the Mailpit UI, or skip mail
+entirely with the `123456` dev-code.
+
+## Observability
+
+A full metrics + logs + traces stack runs alongside the app on the
+internal network (no host ports), as a production mirror. **Grafana**
+and the **Mailpit** UI are reached only through the operator console's
+single `/_gm` Basic Auth gate — one password (the admin-console account)
+unlocks the console, [`/_gm/grafana/`](https://galaxy.lan/_gm/grafana/)
+and [`/_gm/mailpit/`](https://galaxy.lan/_gm/mailpit/), with links in the
+console nav. Grafana runs anonymous-Admin behind the gate (no own
+login); Prometheus, Loki and Tempo stay internal-only.
+
+- **Metrics** — Prometheus scrapes backend, gateway, `node-exporter` and
+  cAdvisor.
+- **Logs** — promtail → Loki (Docker SD on the `galaxy.stack=dev-deploy`
+  label).
+- **Traces** — backend + gateway → Tempo over OTLP.
+
+Grafana's admin user is seeded from `GALAXY_DEV_GRAFANA_ADMIN_PASSWORD`
+(for provisioning/API; the UI needs no Grafana login). See
+[`monitoring/README.md`](monitoring/README.md) for services, configs and
+tuning knobs.
+
 ## Networking
 
 ```
@@ -162,6 +194,8 @@ galaxy-caddy  (networks: edge + galaxy-dev-internal)
    │  /game/*          -> file_server /srv/galaxy-ui   (volume galaxy-dev-ui-dist)
    │  /api/*, /healthz -> reverse_proxy galaxy-api:8080
    │  /rpc/*           -> reverse_proxy galaxy-api:9090 (strips /rpc)
+   │  /_gm, /_gm/*     -> reverse_proxy galaxy-api:8080 (Basic Auth gate;
+   │                      /_gm/grafana/ -> grafana, /_gm/mailpit/ -> mailpit)
    ▼
 galaxy-dev-internal
    ├─ galaxy-api      (gateway:   :8080 REST, :9090 gRPC)
@@ -169,7 +203,9 @@ galaxy-dev-internal
    ├─ galaxy-postgres (postgres:  :5432)
    ├─ galaxy-redis    (redis:     :6379)
    ├─ galaxy-mailpit  (mailpit:   :8025 UI, :1025 SMTP)
-   └─ engine containers (spawned by backend on demand)
+   ├─ engine containers (spawned by backend on demand)
+   └─ observability   (prometheus, grafana, loki, promtail, tempo,
+                       node-exporter, cadvisor)
 ```
 
 The compose project deliberately exposes no host ports. Diagnostics
@@ -214,8 +250,10 @@ make clean-data     Stop everything and wipe volumes + game-state dir
 
 ## Files
 
-- `docker-compose.yml` — six services: postgres, redis, mailpit,
+- `docker-compose.yml` — the application services (postgres, redis,
-  galaxy-backend, galaxy-api, galaxy-caddy. `galaxy-caddy` mounts both
+  mailpit, galaxy-backend, galaxy-api, galaxy-caddy) plus the
+  observability stack (prometheus, grafana, loki, promtail, tempo,
+  node-exporter, cadvisor). `galaxy-caddy` mounts both
   the `galaxy-dev-site-dist` (`/srv/galaxy-site`) and
   `galaxy-dev-ui-dist` (`/srv/galaxy-ui`) volumes and reverse-proxies
   both gateway tiers (REST/health on `:8080`, Connect/gRPC-web on
@@ -227,6 +265,8 @@ make clean-data     Stop everything and wipe volumes + game-state dir
   at `/etc/caddy/Caddyfile`.
 - `Caddyfile.prod` — placeholder for a future prod deployment; not used
   by this compose.
+- `monitoring/` — Prometheus / Loki / promtail / Tempo / Grafana
+  configuration, provisioned as code; see `monitoring/README.md`.
 - `Makefile` — wrapper over `docker compose` with helpers for engine,
   site/UI seeding, health probes, and full wipe.
 - `.env.example` — non-secret defaults for the compose `${VAR:-}`

tools/dev-deploy/monitoring/README.md

@@ -0,0 +1,77 @@
+# `tools/dev-deploy/monitoring/` — observability stack
+
+The long-lived dev environment runs a full metrics + logs + traces stack
+alongside the application as a **production mirror**: the same compose
+fragment and collector configs are meant to back production later. Every
+collector lives on the internal `galaxy-dev-internal` network and
+publishes **no host port**. The browser-reachable pieces (Grafana and
+the Mailpit UI) sit behind the operator console's single `/_gm` Basic
+Auth gate — see [`../README.md`](../README.md) and `ARCHITECTURE.md §14`.
+
+## Services
+
+| Service | Image | Role | Reachable |
+| --- | --- | --- | --- |
+| `galaxy-prometheus` | `prom/prometheus` | Scrape + store metrics (15d) | internal `:9090` |
+| `galaxy-loki` | `grafana/loki` | Log store (7d) | internal `:3100` |
+| `galaxy-promtail` | `grafana/promtail` | Ship container logs to Loki | — |
+| `galaxy-tempo` | `grafana/tempo` | Trace store (3d), OTLP receiver | internal `:3200`, OTLP `:4317`/`:4318` |
+| `galaxy-node-exporter` | `prom/node-exporter` | Host metrics | internal `:9100` |
+| `galaxy-cadvisor` | `cadvisor` | Per-container CPU/memory/IO | internal `:8080` |
+| `galaxy-grafana` | `grafana/grafana` | Dashboards + Explore | Caddy `/_gm/grafana/` |
+
+## What is collected
+
+- **Metrics.** Prometheus (30s interval) scrapes the backend Prometheus
+  endpoint (`galaxy-backend:9100`), the gateway admin endpoint
+  (`galaxy-api:9191`), `node-exporter` (host) and cAdvisor (per
+  container). Engine containers expose no `/metrics`; cAdvisor covers
+  their resource use.
+- **Logs.** promtail discovers containers through the Docker API,
+  filtered to the `galaxy.stack=dev-deploy` label, and ships their
+  stdout/stderr to Loki labelled by `container`.
+- **Traces.** backend and gateway export OTLP traces over gRPC to Tempo
+  (`galaxy-tempo:4317`), plaintext on the internal network
+  (`OTEL_EXPORTER_OTLP_INSECURE=true`, since Tempo's receiver is not
+  TLS-wrapped inside the contour).
+
+## Grafana access (behind the `/_gm` gate)
+
+Grafana is served under `/_gm/grafana/` (`GF_SERVER_ROOT_URL` +
+`GF_SERVER_SERVE_FROM_SUB_PATH=true`) **behind the shared operator gate**:
+the Caddy `/_gm/*` Basic Auth (the admin-console account) is the only
+barrier. Grafana itself runs as **anonymous Admin** with its login form
+and basic auth disabled (`GF_AUTH_ANONYMOUS_ENABLED=true`,
+`GF_AUTH_ANONYMOUS_ORG_ROLE=Admin`, `GF_AUTH_DISABLE_LOGIN_FORM=true`,
+`GF_AUTH_BASIC_ENABLED=false`), so it ignores the forwarded credentials
+and asks for no second password. `GALAXY_DEV_GRAFANA_ADMIN_PASSWORD`
+still seeds the admin user for provisioning/API use.
+
+Datasources (Prometheus, Loki, Tempo) and a starter dashboard
+(`grafana/dashboards/galaxy-overview.json`) are provisioned as code under
+`grafana/provisioning/`.
+
+## Config delivery
+
+`dev-deploy.yaml` copies this directory to a stable host path
+(`$HOME/.galaxy-dev/monitoring`, exported as `GALAXY_DEV_MONITORING_DIR`)
+before `compose up`, and the compose binds it read-only into the
+collectors. A stable path — not the ephemeral CI workspace — keeps the
+mounts valid across container restarts and host reboots (the same lesson
+as the geoip volume; see `../KNOWN-ISSUES.md`).
+
+## Tuning (cost knobs)
+
+Defaults favour the smallest workable footprint; all are config/compose
+values:
+
+- Prometheus `scrape_interval=30s`, `--storage.tsdb.retention.time=15d`.
+- Loki `retention_period=168h` (7d); Tempo `block_retention=72h` (3d).
+- cAdvisor `--housekeeping_interval=30s`.
+- Per-service `deploy.resources.limits.memory` caps (~1.5 GB total cap;
+  steady-state well under that).
+
+Seven always-on containers cost roughly ~1.1 GB steady RAM and
+~1.5–2.5 GB disk at these retention windows. cAdvisor is the main CPU
+cost; on a constrained host it can be dropped (host + app metrics still
+cover most needs).