caddy + pihole: make both boot-persistent and self-healing

Caddy left compose.yaml for a quadlet unit (caddy.service): joins
dankclaw_default for container-name upstreams, Pull=never for the local-only
image, Porkbun credentials via /home/dank/Containers/caddy/env written by
deploy from .env, bare-IP-catch-all health check. deploy_caddy installs,
enables, and starts the unit after retiring the bare container (state is in
host volumes).

Pi-hole: the repo now owns the sysctl drop-in
(dankclaw/pihole/sysctl/99-dnsmasq.conf, ip_unprivileged_port_start=53);
deploy_pihole installs it to /etc/sysctl.d/, stages conflicting later-sorted
drop-ins in the home trash, and applies 'sysctl --system' (the boot code
path). This fixes the 2026-08-26 crash loop (port-53 bind denied, restart
counter 1645) caused by a second drop-in resetting the value to 80.

Tests: new caddy_quadlet.bats seam; caddyfile/deployment_flow assertions
repointed from the removed compose service to the quadlet; pihole.bats pins
the sysctl drop-in and its deployment; test-changed.sh routes dankclaw/caddy/
and the pihole subtree to their seams. Docs: Caddy, Pi-hole, Dankclaw Stack,
work log.

docs/Infrastructure/Caddy.md

@@ -1,6 +1,6 @@
 # Caddy
 
-Caddy is the single reverse proxy for both hosts. It runs as a container on Dankclaw (192.168.0.143), terminates TLS with real Let's Encrypt certificates, routes hostnames to containers on both hosts, and protects the homepage and sensitive services with HTTP basic auth.
+Caddy is the single reverse proxy for both hosts. It runs as a boot-persistent quadlet container (`caddy.service`) on Dankclaw (192.168.0.143), terminates TLS with real Let's Encrypt certificates, routes hostnames to containers on both hosts, and protects the homepage and sensitive services with HTTP basic auth.
 
 **Docs:** https://caddyserver.com/docs
 
@@ -8,6 +8,7 @@ Caddy is the single reverse proxy for both hosts. It runs as a container on Dank
 
 | Item | Value |
 |------|-------|
+| Runtime | Quadlet unit `caddy.service` (`dankclaw/caddy/quadlet/caddy.container`) — boot-persistent, self-healing |
 | Image | `franksdank/caddy-porkbun:latest` (local build, `dankclaw/caddy/Containerfile`) |
 | Config | `/home/dank/Containers/caddy/Caddyfile` (bind mount, rendered by deploy) |
 | Data | `/home/dank/Containers/caddy/data` (certs) and `.../config` (ACME state) |
@@ -15,7 +16,19 @@ Caddy is the single reverse proxy for both hosts. It runs as a container on Dank
 | TLS | Let's Encrypt, DNS-01 via the Porkbun module (one cert per vhost) |
 | Runs on | Dankclaw only — Dankserver has no Caddy |
 
-The Caddyfile in git (`dankclaw/Caddyfile`) carries a `REPLACE_WITH_HASH` placeholder. `scripts/deploy.sh` renders the real basicauth hash from the host `.env` (`CADDY_BASICAUTH_HASH`) into the mounted path before `up`. See [[Deployment Flow]].
+The Caddyfile in git (`dankclaw/Caddyfile`) carries a `REPLACE_WITH_HASH` placeholder. `scripts/deploy.sh` renders the real basicauth hash from the host `.env` (`CADDY_BASICAUTH_HASH`) into the mounted path before start. See [[Deployment Flow]].
+
+## Quadlet (boot persistence)
+
+Caddy left `compose.yaml` on 2026-08-26. A reboot exposed that the bare compose container never comes back: rootless Podman has no boot-time auto-start for bare containers, and `restart: unless-stopped` does not survive the explicit stop that shutdown performs. The quadlet unit is now the only way Caddy starts (see AGENTS.md "Boot Persistence & Self-Healing").
+
+- **Install path on Dankclaw:** `~/.config/containers/systemd/caddy.container` (unit `caddy.service`)
+- **Network:** `dankclaw_default` (the compose bridge — the Caddyfile's container-name upstreams must keep resolving; if no compose service has created the network yet at boot, quadlet creates it first and compose reuses it by name later)
+- **Published ports:** 80/tcp, 443/tcp
+- **Env file:** `/home/dank/Containers/caddy/env` (`PORKBUN_API_KEY`, `PORKBUN_API_SECRET_KEY`) — the deploy writes it from the checkout's `.env`; secrets never enter the repo (placeholders in `dankclaw/caddy/env.example`)
+- **Restart:** `Restart=always`, `RestartSec=5`; the health check probes the bare-IP catch-all (302) inside the container
+- **Image policy:** `Pull=never` — the image is built on-host and exists nowhere else; a boot must not stall on a registry
+- **Deploy:** `./scripts/deploy.sh dankclaw --service caddy` — renders the Caddyfile, rebuilds the image if the Containerfile changed, retires the legacy split proxy, writes the env file, removes the old bare container (all state is in host volumes), then installs, enables, and starts the unit
 
 ## The porkbun image
 
@@ -34,7 +47,7 @@ acme_dns porkbun {
 }
 ```
 
-compose passes both variables from the host `.env`. Keep the real keys in `.env` only; `.env.example` holds placeholders. The Porkbun account holds only `franksdank.cloud`.
+The deploy writes both variables from the host `.env` into `/home/dank/Containers/caddy/env`, which the quadlet reads via `EnvironmentFile`. Keep the real keys in `.env` only; `.env.example` (and `dankclaw/caddy/env.example`) hold placeholders. The Porkbun account holds only `franksdank.cloud`.
 
 ## Vhost map
 
@@ -83,6 +96,7 @@ Certificates and ACME state live in the caddy data volume. Back it up with the s
 
 ## Gotchas
 
+- A bare compose container is **not** boot-persistent: after the 2026-08-26 reboot Caddy stayed down for hours because `restart: unless-stopped` does not survive shutdown's explicit stop. It now runs only from its quadlet unit — do not re-add it to `compose.yaml`.
 - `admin off` disables the config file watcher: rendered changes then sit on disk while Caddy serves its stale in-memory config until the container is recreated, and nothing logs an error (2026-08-22: a broken basicauth hash survived several deploys this way). `tests/caddyfile.bats` forbids `admin off`.
 - The basicauth template must stay a bare `REPLACE_WITH_HASH` token (no `$2a$14$` prefix) — the rendered value is the complete hash. A double prefix silently rejects every password with 401; no Caddy error is logged.
 - A new vhost needs three things: a Pi-hole `addn-hosts` line, a Porkbun A record, and the Caddyfile block. See [[LAN-DNS]].