docs: rewrite CrowdSec enforcement architecture (firewall-bouncer + CF WAF; Yaegi plugin removed)

The Traefik Yaegi CrowdSec bouncer plugin was dead on Traefik 3.7.5 (handler
never invoked) and has been removed. Document the replacement: in-kernel
nftables drop via cs-firewall-bouncer on direct hosts, and a Cloudflare IP-List
+ zone WAF block rule (fed by a LAPI->CF-list sync CronJob) on proxied hosts.
Both add zero per-request latency and fail open.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.claude/CLAUDE.md

@@ -202,7 +202,7 @@ the workflow's built-in `GITHUB_TOKEN` (`packages: write`).
 - **Critical path services scaled to 3**: Traefik, Authentik, CrowdSec LAPI, PgBouncer, Cloudflared.
 - **PDBs**: minAvailable=2 on Traefik and Authentik.
 - **Fallback proxies**: basicAuth when Authentik is down, fail-open when poison-fountain is down.
-- **CrowdSec bouncer**: graceful degradation mode (fail-open on error).
+- **CrowdSec enforcement is out-of-band** (no Traefik plugin/middleware — the dead Yaegi `crowdsec-bouncer-traefik-plugin` was removed on Traefik 3.7.5): banned IPs are dropped **in-kernel via nftables** by the `cs-firewall-bouncer` DaemonSet on **direct** hosts (drops in BOTH the `input` and `forward` hooks — Traefik is ETP=Local so client traffic is DNAT'd to the pod via `forward`; pulls ALL decisions incl. the ~31k CAPI blocklist), and **blocked at the Cloudflare edge** for **proxied** hosts (one `crowdsec_ban` Rules List + a zone WAF block rule, fed by the `crowdsec-cf-sync` CronJob in `rybbit` ns every 2 min — excludes CAPI). Zero per-request latency; **fails open** (LAPI down → no new bans, existing drops persist, legit traffic never blocked). Whitelist covers RFC1918 + tailnet + internal CIDRs. Full as-built: `docs/architecture/security.md`.
 - **Rate limiting**: Return 429 (not 503). Per-service tuning via dedicated middleware + `skip_default_rate_limit` (default 10/s burst 50): Immich 1000/20000, ActualBudget 50/300 (app boot = ~70 parallel revalidations).
 - **Retry middleware**: 2 attempts, 100ms — in default ingress chain.
 - **Entrypoint transport timeouts** (`websecure` `respondingTimeouts`): `writeTimeout=0` (unlimited download duration), `readTimeout=3600s` (uploads ≤1h), `idleTimeout=600s`. These are **HARD total-duration caps**, not nginx-style per-read idle timeouts — a finite `writeTimeout` truncates *any* large download at that wall-clock mark (a prior `writeTimeout=60s` silently cut Immich videos at 60s). **Do NOT re-tighten `writeTimeout`**; keep `readTimeout` finite (slow-loris backstop) but ≥ longest expected upload. Full rationale: `docs/architecture/networking.md` → "Entrypoint Transport Timeouts".
@@ -216,7 +216,7 @@ the workflow's built-in `GITHUB_TOKEN` (`packages: write`).
 |---------|--------------------------|
 | Nextcloud | MaxRequestWorkers=150, needs 8Gi limit (Apache transient memory spikes, see commit eb94144), very generous startup probe |
 | Immich | ML on SSD (CUDA), disable ModSecurity (breaks streaming), frequent upgrades. **`immich-machine-learning` MUST run with `MACHINE_LEARNING_MODEL_TTL > 0`** (set to `600` in `stacks/immich/main.tf`, env on the `immich-machine-learning` deployment). At `0`, no model ever unloads and onnxruntime's CUDA arena (OCR's dynamic input shapes inflate it to ~10 GB) is held forever on the **time-sliced T4 it shares with llama-swap/frigate/immich-server** — which has no VRAM isolation, so immich-ml starved llama-swap (qwen3-8b) and silently broke recruiter-responder triage for ~5 h on 2026-06-02 (post-mortem `docs/post-mortems/2026-06-02-immich-ml-ttl-gpu-oom-recruiter.md`). TTL>0 lets idle models (OCR, face — AND CLIP) free VRAM. The TTL is a single GLOBAL knob (no per-model pin), so CLIP would also unload after 600s idle; the `clip-keepalive` CronJob (`*/5 * * * *`, same stack) pings the CLIP textual encoder so smart-search stays warm without pinning the ad-hoc models. **Smart search has a SECOND warmth layer in Postgres** (don't conflate it with the ML model): the ~665MB vchord `clip_index` must stay resident in PG `shared_buffers`, else an ANN probe that lands on an evicted list pays a ~1.8s cold storage read vs ~4ms warm. The `postStart` hook prewarms it ONCE at pod start and `pg_prewarm.autoprewarm` only re-warms at *startup*, so the index decays out of cache over days under job buffer-pressure (observed ~33% resident after 9d uptime → slow context search, easily misattributed to the ML model). The `clip-index-prewarm` CronJob (`*/5`, same stack) re-runs `pg_prewarm('clip_index')` to pin it hot; `immich-search-probe` (`*/5`) measures live latency + residency → Pushgateway gauges (`immich_smart_search_db_seconds`, `immich_clip_index_cached_pct`) → alerts `ImmichSmartSearchSlow`/`ImmichClipIndexColdCache`/`ImmichSearchProbeStale` + cluster-health check #46 (`check_immich_search`). immich PG role is a superuser so the CronJobs can run `pg_prewarm`/`pg_buffercache`. **Video transcoding is GPU-accelerated**: `immich-server` is pinned to GPU node1 (nodeSelector `nvidia.com/gpu.present` + NoSchedule toleration + `gpu-workload` priority) with a time-sliced `nvidia.com/gpu=1` slice — the stock immich-server image's ffmpeg already ships h264/hevc_nvenc + NVDEC. Activated via `ffmpeg.accel=nvenc` + `accelDecode=true` in the **DB** system-config (`system_metadata` table, key `system-config`, JSONB — NOT Terraform; app config is DB-managed here like oauth/smtp). Direct DB edits need a pod **recreate** to reload (config is cached at boot; only API-driven changes broadcast a reload). **Streaming bitrate is capped** to keep 4K playback smooth on the contended HDD and over remote uplinks: `ffmpeg.maxBitrate=20000k` + `preset=medium` + `transcode=bitrate` (set 2026-06-01 — was uncapped `maxBitrate=0` + `ultrafast` + `targetResolution=original`, which produced 77–264 Mbps 4K transcodes that stuttered for every client, local and remote, since even a single stream needs ~10–13.5 MB/s off the shared `sdc` spindle). 4K resolution is preserved (`targetResolution=original`); originals are NEVER modified — only the `encoded-video/` streaming copy. To re-apply transcode settings to EXISTING videos (config changes only affect new/missing ones): delete the offenders' `asset_file` rows `WHERE type='encoded_video'` (derived/regenerable — never touches originals) then run videoConversion `force=false` (admin Jobs API → "Missing"); it regenerates them to the deterministic `<assetId>.mp4` path at concurrency 1 (gentle on sdc). See `docs/runbooks/immich-transcode-bitrate.md`. If Immich is ever reinstalled fresh (not restored), re-set these keys (accel, accelDecode, **maxBitrate=20000k, preset=medium, transcode=bitrate**). Thumbnails/previews live on SSD NFS (sdb) — do NOT move to block storage (HDD sdc = slower + the contended IO domain). **Background-job concurrency is capped to protect sdc** (DB-managed system-config, `system_metadata` key `system-config`, JSONB `job.*.concurrency`; re-set on fresh install): `thumbnailGeneration=2`, `metadataExtraction=2`, `library=2` — these jobs read ORIGINALS off the HDD library. Left uncapped (were 8/4/4) a library-wide job (e.g. Duplicate Detection on 2026-06-01) fans the ML/thumbnail backfill out into a read storm that saturates sdc and starves etcd → apiserver down. `sidecar`/`smartSearch`/`faceDetection` stay at Immich defaults (small `.xmp` / SSD previews). Apply via Job Settings UI or the `system-config` API; **direct DB edits need an `immich-server` pod recreate to reload** (config cached at boot). See `docs/post-mortems/2026-05-25-immich-anca-elements-io-storm.md`. |
-| CrowdSec | Pin version, disable Metabase when not needed (CPU hog), LAPI scaled to 3, **DB on PostgreSQL** (migrated from MySQL), flush config: max_items=10000/max_age=7d/agents_autodelete=30d, DECISION_DURATION=168h in blocklist CronJob |
+| CrowdSec | Pin version, disable Metabase when not needed (CPU hog), LAPI scaled to 3, **DB on PostgreSQL** (migrated from MySQL), flush config: max_items=10000/max_age=7d/agents_autodelete=30d, DECISION_DURATION=168h in blocklist CronJob. **Enforcement is out-of-band, NOT a Traefik plugin** (the Yaegi `crowdsec-bouncer-traefik-plugin` was dead on Traefik 3.7.5 and removed): `cs-firewall-bouncer` DaemonSet drops in-kernel via nftables on direct hosts (bouncer key `firewall`, v0.0.34 binary fetched at runtime, hostNetwork+NET_ADMIN, `stacks/crowdsec/modules/crowdsec/firewall_bouncer.tf`); `crowdsec-cf-sync` CronJob blocks at the CF edge for proxied hosts (bouncer key `kvsync`, `stacks/rybbit/crowdsec_edge.tf`). Both fail open. See `docs/architecture/security.md` |
 | Frigate | GPU stall detection in liveness probe (inference speed check), high CPU |
 | Authentik | 3 server replicas + 2-replica embedded outpost (PG-backed sessions), PgBouncer in front of PostgreSQL, strip auth headers before forwarding. **`authentik.*` Helm values are INERT** (existingSecret skips chart env rendering) — tune via `server.env`/`worker.env` in `modules/authentik/values.yaml`. Single-screen login (password embedded in identification stage); all first-party OIDC apps use implicit consent (2026-06-10). `/static` ingress carve-out serves assets with immutable Cache-Control. |
 | Kyverno | failurePolicy=Ignore to prevent blocking cluster, pin chart version |