failover: wire up van-modem-watch in deploy.sh

Completes the van-modem-usb-kick -> van-modem-watch swap from the
previous commit: deploy.sh was still installing/enabling the old unit.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

failover/van-modem-watch

@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+"""van-modem-watch — pages if the EC25 modem never enumerates at boot.
+
+Detection only, deliberately no recovery attempt. On 2026-08-04 the modem
+(then on a shared powered USB hub) sometimes failed to enumerate on a cold
+boot. Investigation ruled out a boot-timing race and a bad cable/port: a
+genuine hub-commanded VBUS power-cycle (confirmed via kernel disconnect/
+reconnect events, held off for a full 10s) did not recover it, even with the
+rest of the system already up and stable — only a real physical unplug/
+replug of the connector ever did. That means no software action from this
+host can fix it once it happens; the modem was moved off the hub onto the
+Pi's native USB port as the actual fix (a direct port doesn't reproduce the
+failure). This just watches for a recurrence and pages, since if it comes
+back the only real fix is someone physically reseating the connector.
+
+Pushover credentials shared with van-battery/van-thermal/van-nvme-watch
+(/etc/van-battery/pushover.json, 0600). Publishes /run/van-modem-watch/
+state.json (same convention as the other watchdogs). Stdlib only.
+
+Usage: van-modem-watch [modem-usb-vendor]
+Defaults to 2c7c (Quectel) — see deploy.conf.
+"""
+
+import json
+import socket
+import sys
+import time
+import urllib.parse
+import urllib.request
+from datetime import datetime, timezone
+from pathlib import Path
+
+MODEM_VENDOR = sys.argv[1] if len(sys.argv) > 1 else "2c7c"
+INTERVAL = 20            # seconds between checks
+BUDGET_S = 6 * INTERVAL  # ~2 minutes of retries after boot, then give up quietly
+USB_DEVICES = Path("/sys/bus/usb/devices")
+STATE_DIR = Path("/run/van-modem-watch")
+STATE_PATH = STATE_DIR / "state.json"
+CREDENTIALS_PATH = Path("/etc/van-battery/pushover.json")
+HOST = socket.gethostname()
+PLACEHOLDERS = {"", "REPLACE_ME", "your-token-here", "your-user-key-here"}
+
+
+def log(msg, level="info"):
+    # systemd journal severity prefixes (sd-daemon), same convention as van-ap-watchdog.
+    pri = {"info": "<6>", "warn": "<4>", "crit": "<2>"}.get(level, "<6>")
+    print(pri + msg, flush=True)
+
+
+def modem_present(vendor):
+    for f in USB_DEVICES.glob("*/idVendor"):
+        try:
+            if f.read_text().strip() == vendor:
+                return True
+        except OSError:
+            continue
+    return False
+
+
+def load_creds():
+    try:
+        c = json.loads(CREDENTIALS_PATH.read_text())
+        token, user = str(c.get("token", "")).strip(), str(c.get("user", "")).strip()
+        if token in PLACEHOLDERS or user in PLACEHOLDERS:
+            return None
+        return token, user
+    except FileNotFoundError:
+        return None
+    except Exception as e:
+        log(f"credentials {CREDENTIALS_PATH} unreadable ({e})", "warn")
+        return None
+
+
+def pushover(title, message, attempts=3, retry_delay=15):
+    creds = load_creds()
+    if not creds:
+        log(f"pushover skipped (no credentials): {title} — {message}", "warn")
+        return False
+    token, user = creds
+    data = urllib.parse.urlencode({
+        "token": token, "user": user, "title": title, "message": message,
+    }).encode()
+    req = urllib.request.Request("https://api.pushover.net/1/messages.json", data=data)
+    for attempt in range(1, attempts + 1):
+        try:
+            with urllib.request.urlopen(req, timeout=10) as resp:
+                ok = resp.status == 200
+            if not ok:
+                log(f"pushover HTTP {resp.status}", "warn")
+            return ok
+        except Exception as e:
+            last = attempt == attempts
+            log(f"pushover send failed ({attempt}/{attempts}): {e}", "warn")
+            if not last:
+                time.sleep(retry_delay)
+    return False
+
+
+def write_state(payload):
+    STATE_DIR.mkdir(parents=True, exist_ok=True)
+    tmp = STATE_PATH.with_suffix(".tmp")
+    tmp.write_text(json.dumps(payload))
+    tmp.replace(STATE_PATH)
+
+
+def main():
+    log(f"van-modem-watch up: watching for USB vendor {MODEM_VENDOR} for up to "
+        f"{BUDGET_S}s after boot")
+    elapsed = 0
+    while elapsed < BUDGET_S:
+        if modem_present(MODEM_VENDOR):
+            log("modem present — exiting")
+            write_state({
+                "updated": datetime.now(timezone.utc).isoformat(timespec="seconds"),
+                "present": True,
+            })
+            return
+        time.sleep(INTERVAL)
+        elapsed += INTERVAL
+
+    message = (f"modem (USB vendor {MODEM_VENDOR}) not seen {BUDGET_S}s after boot — "
+               f"needs a physical unplug/replug, no software fix works for this")
+    log(message, "crit")
+    write_state({
+        "updated": datetime.now(timezone.utc).isoformat(timespec="seconds"),
+        "present": False,
+    })
+    pushover(f"🚨 {HOST}: cellular modem absent after boot", message)
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except KeyboardInterrupt:
+        sys.exit(0)

failover/van-modem-watch.service

@@ -0,0 +1,11 @@
+[Unit]
+Description=EC25 modem boot-presence watchdog — pages if it never enumerated (no auto-recovery, see script docstring)
+After=systemd-udev-settle.service
+Wants=systemd-udev-settle.service
+
+[Service]
+Type=simple
+ExecStart=/usr/local/sbin/van-modem-watch @MODEM_USB_VENDOR@
+
+[Install]
+WantedBy=multi-user.target