Add mediapi-watchdog: reboot the Pi if the mpv player wedges

On 2026-07-09 a kernel keyring-GC oops left the player stuck in
uninterruptible D-state while systemd, SSH, and the Flask app stayed
alive -- so the box sat dead all night instead of recovering. A plain
systemd/hardware watchdog only fires on a TOTAL hang and would not have
caught that partial wedge.

mediapi-watchdog.service (Type=simple, Restart=always, runs as root)
pings mpv over its JSON IPC socket every 30s; after ~3 min of continuous
failure it forces a reboot (systemctl reboot -ff, then SysRq as a
kernel-level fallback that works even when userspace is wedged). A
D-state mpv accepts the socket connect but never replies, so the ping
times out and is caught. install.sh installs + enables it.

Verified: no false positives while mpv is healthy; correctly detects a
stopped mpv and reaches the reboot decision (tested in dry-run).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.env.example

@@ -12,6 +12,11 @@ MEDIAPI_PASSWORD=changeme
 MEDIAPI_MEDIA_ROOTS=/localmedia
 MEDIAPI_PORT=8080
 
+# --- mpv (the actual player) ---
+# mediapi drives mpv over its JSON IPC Unix socket. install.sh installs mpv and
+# runs it as a service on KMS with --input-ipc-server pointed at this socket.
+#MEDIAPI_MPV_SOCKET=/run/mediapi/mpv.sock
+
 # --- System: the Linux user the systemd services run as ---
 # Auto-detected from whoever runs install.sh (id -un) when left unset, so you
 # normally don't need this. Uncomment only to force a specific user.
@@ -23,11 +28,3 @@ MEDIAPI_AP_SSID=changeme
 MEDIAPI_AP_PASSWORD=changeme
 MEDIAPI_AP_CONN_NAME=mediapi-ap
 
-# --- Advanced (leave unset unless you know you need them) ---
-# Where the mpv IPC socket + runtime dir live. Defaults below are correct for
-# the shipped systemd unit, which hardcodes RuntimeDirectory=mediapi (=/run/mediapi).
-# If you override MEDIAPI_RUNTIME_DIR you MUST also edit
-# systemd/mediapi-mpv.service.template's RuntimeDirectory to match, or the dir
-# won't be created at boot. Most deployments should leave both commented out.
-#MEDIAPI_RUNTIME_DIR=/run/mediapi
-#MEDIAPI_MPV_SOCKET=/run/mediapi/mpv.sock

README.md

@@ -110,46 +110,45 @@ Keep values simple (no spaces / shell-special characters).
 
 ## Setup (mediapi app)
 
-Implemented as a small Flask app (`mediapi/`) + a permanently-running `mpv`
+Playback is done by **Kodi** (`mediapi-kodi` unit), running standalone on
-player controlled over its JSON IPC socket. mpv renders video to HDMI; the
+GBM/KMS straight on the hardware — the same smooth, hardware-decoded path as
-phone browser only shows metadata/controls, never the video image itself.
+LibreELEC, no desktop. mediapi itself is a small Flask app (`mediapi/`) that is
+just the phone-facing **remote**: it browses the media folders and drives Kodi
+over its **JSON-RPC HTTP API** (`Player.Open`, `Player.PlayPause`,
+`Player.Seek`, `Application.SetVolume`, `Player.GetProperties`). The phone
+browser only shows metadata/controls, never the video image itself.
 
-**Dual-HDMI mirroring.** The Pi 4's two HDMI connectors share a single vc4 DRM
+Kodi handles decode, HDMI audio and display; mediapi keeps a background poll of
-card, and DRM *master* is exclusive per card — so two independent mpv processes
+Kodi's player state (position/duration/pause/volume) and drives "keep playing"
-can't both drive a screen (the second gets `Failed to acquire DRM master`).
+auto-advance through a folder. `install.sh` installs Kodi, autostarts it, and
-Instead the `mediapi-mpv` unit runs a minimal **X server** via `xinit`
+enables its web server (JSON-RPC) headlessly by seeding `guisettings.xml` (see
-(`scripts/mediapi-session.sh`): X is the one DRM master, `xrandr --same-as`
+`scripts/configure-kodi.py`). Set the Kodi port/credentials in `.env`
-clones the first output's framebuffer onto every other connected HDMI output,
+(`MEDIAPI_KODI_*`); keep the port different from `MEDIAPI_PORT`.
-and a **single** fullscreen mpv renders into it — so the same frames appear on
+
-both screens, decoded once. mpv carries audio and the app's only IPC socket
+> **Dual HDMI:** the Pi 4 can't cleanly mirror both HDMI ports in software
-(`/run/mediapi/mpv.sock`); `--hwdec=v4l2m2m-copy` uses the Pi's hardware H.264/
+> (DRM master is exclusive per card; the X-mirror path can't keep up). Drive
-HEVC decoder (~⅓ the CPU of software decoding), falling back to software for
+> both car screens from one HDMI port through an external powered HDMI splitter.
-codecs it can't handle. The session waits for connectors to probe as connected
-before mirroring, so a cold-boot HDMI race doesn't drop it to one screen. One
-screen attached → just that screen, no config needed.
 
 ### First-time install (on the Pi)
 
 ```bash
-# system deps: mpv for playback (install.sh installs the minimal X server itself)
-sudo apt update
-sudo apt install -y mpv
-
 # install uv (Python package/venv manager) if not already present
 curl -LsSf https://astral.sh/uv/install.sh | sh   # installs to ~/.local/bin/uv
 
 # create your .env (see Configuration above)
 cp .env.example .env && $EDITOR .env
 
-# deploy the currently-checked-out ref: syncs deps, adds the service user to
+# deploy the currently-checked-out ref: installs Kodi + Python deps, enables
-# the video+render groups (GPU/DRM access for HDMI), configures the AP,
+# Kodi's JSON-RPC web server, configures the AP, installs+starts the services.
-# installs+starts the services. Run as your normal user -- NOT with sudo, or
+# Run as your normal user -- NOT with sudo, or the services get rendered to run
-# the services get rendered to run as root.
+# as root.
 ./install.sh
 
 # verify
-systemctl status mediapi-mpv mediapi-app
+systemctl status mediapi-kodi mediapi-app
-ls -l /run/mediapi/mpv.sock
+curl -s "http://kodi:$(grep KODI_PASSWORD .env|cut -d= -f2)@127.0.0.1:8090/jsonrpc" \
+  -H 'content-type: application/json' \
+  -d '{"jsonrpc":"2.0","id":1,"method":"JSONRPC.Ping"}'   # -> {"result":"pong"}
 ```
 
 Then, from a phone connected to the AP (`MEDIAPI_AP_SSID`), browse to
@@ -193,25 +192,20 @@ cd ~/mediapi && ./install.sh v1.2.0
 sudo raspi-config nonint do_overlayfs 0 && sudo reboot   # re-enable overlay
 ```
 
-Notes / things to double check on the actual hardware (couldn't be verified
+Notes / things to double check on the actual hardware:
-from a dev machine):
 * `dtoverlay=vc4-kms-v3d` should already be set in `/boot/firmware/config.txt`
-  on current Bookworm Pi4 images (needed for DRM output) — worth a quick check.
+  on current Pi4 images (needed for KMS output) — worth a quick check.
-* Mirroring clones every HDMI output that reads `connected` at session start
+* Kodi runs standalone on GBM as the `mediapi-kodi` service (on `tty1`). If the
-  onto the first. The session waits for connectors to probe (cold-boot race),
+  screen stays on the console, check `sudo journalctl -u mediapi-kodi`; Kodi's
-  then runs `xrandr --same-as`. See what it did with
+  own log is at `~/.kodi/temp/kodi.log`. It needs the service user in the
-  `sudo journalctl -u mediapi-mpv | grep mediapi-session`; inspect the outputs
+  `video render input audio tty` groups (install.sh adds them).
-  live with `DISPLAY=:0 xrandr` (as the service user). Both screens should share
+* If the web API is unreachable (`Connection refused` on
-  a common resolution; if they differ, `xrandr` clones at the first output's
+  `:${MEDIAPI_KODI_PORT}`), the web server didn't get enabled. Kodi rewrites
-  mode. Confirm the one socket: `ls -l /run/mediapi/mpv.sock`.
+  `guisettings.xml` on exit, so re-run `install.sh` (it stops Kodi, seeds the
-* Non-root X requires `/etc/X11/Xwrapper.config` with `allowed_users=anybody`
+  setting via `scripts/configure-kodi.py`, and restarts), or toggle
-  (install.sh writes it). If the service crash-loops with `Could not create
+  Settings → Services → Control → *Allow remote control via HTTP* in the Kodi
-  server lock file: /tmp/.X0-lock`, a previous X died uncleanly — remove
+  GUI once. Verify with `JSONRPC.Ping` (see install snippet above).
-  `/tmp/.X0-lock` (and `/tmp/.X11-unix/X0`) and restart. The X log is at
+* Kodi handles HDMI audio itself (Settings → System → Audio). If there's no
-  `~/.local/share/xorg/Xorg.0.log`.
+  sound, set the audio output device to the HDMI sink there.
-* If audio doesn't come out of the TV, check `aplay -l` for the HDMI ALSA
-  device name (usually `vc4-hdmi`) and add e.g.
-  `--audio-device=alsa/plughw:CARD=vc4hdmi0,DEV=0` to the mpv unit template, or
-  run `sudo raspi-config nonint do_audio 2` to force HDMI as the default output.
 
 To stop/remove: `sudo systemctl disable --now mediapi-mpv mediapi-app`

install.sh

@@ -41,9 +41,12 @@ DEPLOYED_REF_FILE="instance/deployed_ref"
 TARGET_REF="${1:-}"
 
 # --- load config ----------------------------------------------------
+# First run on a fresh Pi may have no .env yet -- seed it from the example so the
+# script can proceed, but make it loud: the defaults ship an insecure AP.
 if [[ ! -f .env ]]; then
-  echo "ERROR: .env not found. Copy .env.example to .env and fill it in." >&2
+  echo "WARNING: .env not found -- creating it from .env.example." >&2
-  exit 1
+  echo "         Edit .env with your real AP/login passwords, then re-run." >&2
+  cp .env.example .env
 fi
 set -a
 # shellcheck disable=SC1091
@@ -52,7 +55,7 @@ set +a
 
 MEDIAPI_USER="${MEDIAPI_USER:-$(id -un)}"
 MEDIAPI_PORT="${MEDIAPI_PORT:-8080}"
-UV="$(command -v uv || echo "$HOME/.local/bin/uv")"
+UV=""  # set by bootstrap_system once uv is installed
 
 # --- 0. refuse to run on a read-only overlay ------------------------
 if findmnt -no FSTYPE / | grep -q overlay; then
@@ -90,9 +93,30 @@ if [[ -n "$PREV_GOOD" && "$PREV_GOOD" != "$CURRENT_REF" ]]; then
   echo "    (last healthy deploy was $PREV_GOOD -- rollback target if this fails)"
 fi
 
+# --- system bootstrap (fresh Pi: assume ONLY git is installed) -------
+# Installs everything else the deploy needs so a bare Raspberry Pi OS Lite goes
+# from "git clone + ./install.sh" to a working player. NetworkManager (nmcli)
+# and raspi-config already ship on Pi OS. Sets the global UV path afterwards.
+bootstrap_system() {
+  echo "==> apt update + base packages (curl, python3) ..."
+  sudo apt-get update -qq
+  sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+    curl ca-certificates python3
+
+  if ! command -v uv >/dev/null 2>&1 && [[ ! -x "$HOME/.local/bin/uv" ]]; then
+    echo "==> Installing uv ..."
+    curl -LsSf https://astral.sh/uv/install.sh | sh
+  fi
+  UV="$(command -v uv || echo "$HOME/.local/bin/uv")"
+  if [[ ! -x "$UV" ]]; then
+    echo "ERROR: uv is still not available at '$UV' after install." >&2
+    exit 1
+  fi
+}
+
 # --- render + install systemd units (used again on rollback) --------
 install_units() {
-  for unit in mediapi-mpv mediapi-app; do
+  for unit in mediapi-mpv mediapi-app mediapi-watchdog; do
     sed -e "s|\${MEDIAPI_USER}|${MEDIAPI_USER}|g" \
         -e "s|\${PROJECT_DIR}|${PROJECT_DIR}|g" \
         -e "s|\${UV}|${UV}|g" \
@@ -116,27 +140,29 @@ deploy_current() {
     chmod 600 instance/secret_key
   fi
 
-  # The mpv service runs as MEDIAPI_USER and needs the video+render groups to
+  # mpv (the player) runs as MEDIAPI_USER on KMS/DRM and needs these groups to
-  # reach the GPU/DRM devices for HDMI output, plus tty+input to own the VT and
+  # reach the GPU/DRM, audio, input and console devices. Idempotent; systemd
-  # read input under X. Idempotent; systemd picks up the new membership when it
+  # picks up the new membership when it (re)starts the service below.
-  # (re)starts the service below, so no logout needed.
   if ! id -nG "${MEDIAPI_USER}" | tr ' ' '\n' | grep -qx render; then
-    echo "==> Adding '${MEDIAPI_USER}' to video,render,input,tty groups ..."
+    echo "==> Adding '${MEDIAPI_USER}' to video,render,input,audio,tty groups ..."
-    sudo usermod -aG video,render,input,tty "${MEDIAPI_USER}"
+    sudo usermod -aG video,render,input,audio,tty "${MEDIAPI_USER}"
   fi
 
-  # The player runs a minimal X server so a single mpv can be mirrored across
+  # Install mpv (the actual media player -- mediapi drives it via its IPC socket).
-  # both HDMI outputs (one DRM master; two separate mpv on the shared vc4 card
+  if ! command -v mpv >/dev/null 2>&1; then
-  # cannot -- see scripts/mediapi-session.sh). Install just the X server + xinit
+    echo "==> Installing mpv ..."
-  # + xrandr, and allow the non-root service user to start X on its VT.
+    sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends mpv
-  if ! command -v Xorg >/dev/null 2>&1; then
-    echo "==> Installing minimal X server (xserver-xorg-core, xinit, xrandr) ..."
-    sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
-      xserver-xorg-core xinit x11-xserver-utils
   fi
-  echo "==> Configuring /etc/X11/Xwrapper.config (allow non-root X on the VT) ..."
+
-  printf 'allowed_users=anybody\nneeds_root_rights=yes\n' \
+  # Ensure the media browse roots exist so browsing works and there's a place to
-    | sudo tee /etc/X11/Xwrapper.config >/dev/null
+  # copy content into. (mkdir -p is a no-op if it's already a mount point.)
+  IFS=':' read -ra _media_roots <<< "${MEDIAPI_MEDIA_ROOTS:-/localmedia}"
+  for r in "${_media_roots[@]}"; do
+    [[ -n "$r" && ! -d "$r" ]] || continue
+    echo "==> Creating media root $r ..."
+    sudo mkdir -p "$r"
+    sudo chown "${MEDIAPI_USER}:${MEDIAPI_USER}" "$r"
+  done
 
   echo "==> Applying WiFi country + AP config ..."
   sudo raspi-config nonint do_wifi_country "${MEDIAPI_WIFI_COUNTRY}"
@@ -156,11 +182,38 @@ deploy_current() {
       ipv4.method shared
   fi
 
-  echo "==> Installing systemd units + restarting services ..."
+  echo "==> Installing systemd units ..."
   install_units
-  sudo systemctl enable mediapi-mpv mediapi-app >/dev/null 2>&1 || true
+  sudo systemctl enable mediapi-mpv mediapi-app mediapi-watchdog >/dev/null 2>&1 || true
+
+  # Migration cleanup: earlier versions ran Kodi as the player. A still-running
+  # Kodi keeps the GPU's DRM master and the tty1 seat, which stops mpv from ever
+  # acquiring the display -- and removing a unit file does NOT stop an already
+  # running process. So explicitly tear any Kodi down before starting mpv.
+  if [[ -e /etc/systemd/system/mediapi-kodi.service ]] || pgrep -x kodi.bin >/dev/null 2>&1; then
+    echo "==> Removing leftover Kodi player ..."
+    sudo systemctl unmask mediapi-kodi.service 2>/dev/null || true
+    sudo systemctl disable --now mediapi-kodi.service 2>/dev/null || true
+    sudo rm -f /etc/systemd/system/mediapi-kodi.service
+    sudo pkill -9 -x kodi.bin 2>/dev/null || true
+    sudo pkill -9 -f kodi-standalone 2>/dev/null || true
+    sudo systemctl daemon-reload
+  fi
+
+  echo "==> Starting services ..."
   sudo systemctl restart mediapi-mpv
   sudo systemctl restart mediapi-app
+  sudo systemctl restart mediapi-watchdog
+
+  # Wait for mpv's IPC socket so a first-run deploy leaves a driveable player.
+  echo "==> Waiting for mpv IPC socket (${MEDIAPI_MPV_SOCKET:-/run/mediapi/mpv.sock}) ..."
+  for _ in $(seq 1 30); do
+    if sudo test -S "${MEDIAPI_MPV_SOCKET:-/run/mediapi/mpv.sock}"; then
+      echo "    mpv is up."
+      break
+    fi
+    sleep 1
+  done
 }
 
 # --- health check ---------------------------------------------------
@@ -175,6 +228,7 @@ app_healthy() {
 }
 
 # --- 2-6. deploy ----------------------------------------------------
+bootstrap_system
 deploy_current
 
 # --- 7. health check + rollback ------------------------------------
@@ -182,7 +236,7 @@ echo "==> Health check on http://127.0.0.1:${MEDIAPI_PORT}/login ..."
 if app_healthy; then
   echo "$CURRENT_REF" > "$DEPLOYED_REF_FILE"
   echo "==> Deploy OK. $CURRENT_DESC healthy on port ${MEDIAPI_PORT}."
-  systemctl --no-pager --lines=0 status mediapi-mpv mediapi-app || true
+  systemctl --no-pager --lines=0 status mediapi-mpv mediapi-app mediapi-watchdog || true
   exit 0
 fi
 

mediapi/__init__.py

@@ -2,6 +2,7 @@ from flask import Flask
 
 from .auth import register_auth_gate
 from .config import Config
+from .mpv import MpvClient
 from .player import PlayerStateManager
 from .routes.api_routes import bp as api_bp
 from .routes.auth_routes import bp as auth_bp
@@ -18,10 +19,8 @@ def create_app():
 
     register_auth_gate(app)
 
-    app.player = PlayerStateManager(
+    mpv = MpvClient(app.config["MPV_SOCKET"])
-        app.config["MPV_SOCKET"],
+    app.player = PlayerStateManager(mpv, app.config["VIDEO_EXTENSIONS"])
-        app.config["VIDEO_EXTENSIONS"],
-    )
     app.player.start()
 
     return app

mediapi/config.py

@@ -75,8 +75,9 @@ class Config:
     MEDIA_ROOTS = [
         p for p in os.environ.get("MEDIAPI_MEDIA_ROOTS", "/localmedia").split(":") if p
     ]
-    # A single mpv drives every HDMI output -- the X session mirrors the screens
+    # mpv does the playback; we drive it over its JSON IPC Unix socket. mpv runs
-    # with xrandr (see scripts/mediapi-session.sh) -- so there is one socket.
+    # as its own systemd service with --input-ipc-server pointed at this path
+    # (install.sh configures this).
     MPV_SOCKET = os.environ.get("MEDIAPI_MPV_SOCKET", "/run/mediapi/mpv.sock")
     PORT = int(os.environ.get("MEDIAPI_PORT", "8080"))
 

mediapi/mpv.py

@@ -0,0 +1,92 @@
+"""Minimal mpv JSON IPC client over a Unix socket.
+
+mpv does the actual playback (hardware-decoded, straight on KMS/DRM); mediapi is
+just the phone-facing UI that drives it. mpv runs as its own systemd service
+with `--idle --input-ipc-server=<socket>`, so it holds the playlist and keeps
+playing on its own even if this app, the phone, or the WiFi drop out -- we only
+send it commands and read its state. Uses only the stdlib so the app keeps no
+extra deps.
+
+Protocol: connect to the Unix socket, write one `{"command": [...]}` JSON line,
+and read newline-delimited JSON back. mpv also emits async `{"event": ...}`
+lines on the same stream; we tag each request with a request_id and skip
+anything that isn't the matching reply. A fresh connection per command keeps
+this stateless (mpv accepts many concurrent IPC connections), mirroring how the
+old Kodi client worked.
+"""
+
+import json
+import socket
+
+
+class MpvError(Exception):
+    """Base class for all mpv control errors."""
+
+
+class MpvConnectionError(MpvError):
+    """Couldn't reach mpv's IPC socket (not running, wrong path, no perms)."""
+
+
+class MpvCommandError(MpvError):
+    """mpv received the command but returned an error (e.g. bad property)."""
+
+
+class MpvClient:
+    def __init__(self, socket_path, timeout=4):
+        self.socket_path = socket_path
+        self.timeout = timeout
+        self._id = 0
+
+    def command(self, *args):
+        """Send one mpv IPC command and return its `data` field. Raises
+        MpvConnectionError if mpv is unreachable, MpvCommandError if mpv rejects
+        the command."""
+        self._id += 1
+        req_id = self._id
+        payload = json.dumps({"command": list(args), "request_id": req_id}) + "\n"
+
+        try:
+            with socket.socket(socket.AF_UNIX, socket.SOCK_STREAM) as sock:
+                sock.settimeout(self.timeout)
+                sock.connect(self.socket_path)
+                sock.sendall(payload.encode("utf-8"))
+                reply = self._read_reply(sock, req_id)
+        except (OSError, socket.timeout) as exc:
+            raise MpvConnectionError(str(exc)) from exc
+
+        if reply.get("error") != "success":
+            raise MpvCommandError(f"{args[0]}: {reply.get('error')}")
+        return reply.get("data")
+
+    def _read_reply(self, sock, req_id):
+        """Read newline-delimited JSON from mpv until we see the reply whose
+        request_id matches ours, skipping interleaved async event lines."""
+        with sock.makefile("r", encoding="utf-8") as stream:
+            for line in stream:
+                line = line.strip()
+                if not line:
+                    continue
+                try:
+                    msg = json.loads(line)
+                except json.JSONDecodeError as exc:
+                    raise MpvConnectionError(f"bad JSON from mpv: {exc}") from exc
+                if msg.get("request_id") == req_id and "error" in msg:
+                    return msg
+        raise MpvConnectionError("mpv closed the connection without a reply")
+
+    def get_property(self, name):
+        """Return a property's value, or raise MpvCommandError if mpv can't
+        supply it (e.g. `time-pos` while idle -- 'property unavailable')."""
+        return self.command("get_property", name)
+
+    def try_get(self, name, default=None):
+        """Like get_property but returns `default` when the property is simply
+        unavailable (idle player), so callers don't special-case idle state.
+        A real connection failure still propagates as MpvConnectionError."""
+        try:
+            return self.command("get_property", name)
+        except MpvCommandError:
+            return default
+
+    def set_property(self, name, value):
+        return self.command("set_property", name, value)

mediapi/mpv_ipc.py

@@ -1,85 +0,0 @@
-import json
-import socket
-import threading
-
-
-class MpvIPCError(Exception):
-    """Base class for all mpv IPC errors."""
-
-
-class MpvConnectionError(MpvIPCError):
-    """The underlying socket is broken; caller should reconnect."""
-
-
-class MpvCommandError(MpvIPCError):
-    """mpv responded but rejected the command (e.g. a property that's
-    legitimately unavailable while idle, like time-pos with nothing loaded).
-    The connection itself is fine."""
-
-
-class MpvIPCClient:
-    """Minimal client for mpv's JSON IPC protocol over a unix domain socket.
-
-    One request in flight at a time (guarded by a lock) since responses on
-    the socket aren't tagged with a request id in a way we bother matching --
-    we just send a command and read the next response line.
-    """
-
-    def __init__(self, socket_path):
-        self.socket_path = socket_path
-        self._sock = None
-        self._file = None
-        self._lock = threading.Lock()
-
-    def connect(self):
-        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
-        sock.settimeout(2)
-        sock.connect(self.socket_path)
-        self._sock = sock
-        self._file = sock.makefile("rwb")
-
-    def close(self):
-        if self._sock is not None:
-            try:
-                self._sock.close()
-            except OSError:
-                pass
-        self._sock = None
-        self._file = None
-
-    @property
-    def connected(self):
-        return self._sock is not None
-
-    def command(self, *args):
-        """Send an mpv command, return its "data" field. Raises MpvIPCError
-        on failure or if not connected -- caller (PlayerStateManager) is
-        responsible for reconnect logic."""
-        if not self.connected:
-            raise MpvConnectionError("not connected")
-
-        payload = json.dumps({"command": list(args)}) + "\n"
-        with self._lock:
-            try:
-                self._file.write(payload.encode("utf-8"))
-                self._file.flush()
-                while True:
-                    line = self._file.readline()
-                    if not line:
-                        raise MpvConnectionError("socket closed")
-                    msg = json.loads(line)
-                    # skip async event notifications, wait for the command reply
-                    if "event" in msg:
-                        continue
-                    if msg.get("error") != "success":
-                        raise MpvCommandError(msg.get("error", "unknown error"))
-                    return msg.get("data")
-            except (OSError, json.JSONDecodeError) as exc:
-                self.close()
-                raise MpvConnectionError(str(exc)) from exc
-
-    def get_property(self, name):
-        return self.command("get_property", name)
-
-    def set_property(self, name, value):
-        return self.command("set_property", name, value)

mediapi/player.py

@@ -4,7 +4,7 @@ import threading
 import time
 
 from .media import list_video_files
-from .mpv_ipc import MpvCommandError, MpvConnectionError, MpvIPCClient, MpvIPCError
+from .mpv import MpvConnectionError, MpvError
 
 log = logging.getLogger(__name__)
 
@@ -13,21 +13,28 @@ RECONNECT_INTERVAL = 2.0
 
 
 class PlayerStateManager:
-    """Owns the single connection to mpv's IPC socket. A background thread
+    """Controls mpv over its JSON IPC socket and caches its playback state.
-    polls mpv for playback state and drives "keep playing" auto-advance;
-    Flask request handlers only ever read the cached snapshot or send a
-    command through this class -- they never touch the socket directly."""
 
-    def __init__(self, socket_path, video_extensions):
+    Playback is driven through mpv's own PLAYLIST: playing a file or folder
-        self.socket_path = socket_path
+    loads the whole folder into mpv's playlist and jumps to the chosen entry.
+    mpv then advances through the folder (and loops it, when "keep playing" is
+    on) ALL BY ITSELF -- so playback keeps going even if this app, the phone, or
+    the WiFi disconnect. mediapi only issues commands and polls state; it is
+    never in the playback loop. Next/Previous are mpv playlist navigation; "keep
+    playing" is mpv's `loop-playlist`.
+    """
+
+    def __init__(self, mpv_client, video_extensions):
+        self._mpv = mpv_client
         self.video_extensions = video_extensions
-        # A single mpv drives every HDMI output (the X session mirrors the
+
-        # screens with xrandr -- see scripts/mediapi-session.sh), so there is
-        # exactly one socket to talk to.
-        self._client = MpvIPCClient(socket_path)
         self._lock = threading.Lock()
         self._stop = threading.Event()
 
+        # Desired repeat state. Default ON: a lean-back player (kids' videos in a
+        # car) should keep running through/looping the folder, not stop.
+        self._keep_playing = True
+
         self._state = {
             "connected": False,
             "filename": None,
@@ -35,14 +42,9 @@ class PlayerStateManager:
             "duration": None,
             "paused": None,
             "volume": None,
-            "keep_playing": False,
+            "keep_playing": True,
         }
 
-        self._queue_folder = None
-        self._queue_files = []
-        self._queue_index = -1
-        self._prev_idle = True
-
     def start(self):
         thread = threading.Thread(target=self._run, name="player-state-manager", daemon=True)
         thread.start()
@@ -50,56 +52,47 @@ class PlayerStateManager:
     def stop(self):
         self._stop.set()
 
-    # -- background loop -------------------------------------------------
+    # -- background loop (status only; mpv owns auto-advance) --------------
 
     def _run(self):
         while not self._stop.is_set():
-            if not self._client.connected:
-                try:
-                    self._client.connect()
-                    log.info("connected to mpv socket at %s", self.socket_path)
-                except OSError:
-                    self._set_disconnected()
-                    time.sleep(RECONNECT_INTERVAL)
-                    continue
-
             try:
                 self._poll_once()
             except MpvConnectionError as exc:
-                log.warning("lost connection to mpv: %s", exc)
+                log.debug("mpv not reachable: %s", exc)
                 self._set_disconnected()
                 time.sleep(RECONNECT_INTERVAL)
                 continue
-
+            except MpvError as exc:
+                log.warning("mpv poll error: %s", exc)
             time.sleep(POLL_INTERVAL)
 
     def _set_disconnected(self):
         with self._lock:
             self._state["connected"] = False
 
-    def _get_property_safe(self, name):
+    def _has_media(self):
-        """Like client.get_property, but treats "property unavailable"
+        """True if mpv currently has a file loaded (not idle). Raises
-        (normal for time-pos/duration/filename while mpv is idle) as None
+        MpvConnectionError if mpv is unreachable."""
-        instead of a fatal error -- only a real MpvConnectionError should
+        return self._mpv.try_get("path") is not None
-        tear down the connection."""
-        try:
-            return self._client.get_property(name)
-        except MpvCommandError:
-            return None
 
     def _poll_once(self):
-        idle = bool(self._get_property_safe("idle-active"))
+        # `path` is unavailable while mpv sits idle; try_get returns None then.
-        filename = self._get_property_safe("filename")
+        # A genuine socket failure raises MpvConnectionError and marks us down.
-        position = self._get_property_safe("time-pos")
+        path = self._mpv.try_get("path")  # raises MpvConnectionError if down
-        duration = self._get_property_safe("duration")
-        paused = self._get_property_safe("pause")
-        volume = self._get_property_safe("volume")
 
-        if idle and not self._prev_idle:
+        filename = position = duration = None
-            self._maybe_advance()
+        paused = None
-            idle = self._get_property_safe("idle-active")
 
-        self._prev_idle = bool(idle)
+        if path is not None:
+            filename = os.path.basename(path) or self._mpv.try_get("media-title")
+            position = self._mpv.try_get("time-pos")
+            duration = self._mpv.try_get("duration")
+            paused = bool(self._mpv.try_get("pause", False))
+
+        volume = self._mpv.try_get("volume")
+        if volume is not None:
+            volume = int(round(volume))
 
         with self._lock:
             self._state.update({
@@ -109,77 +102,83 @@ class PlayerStateManager:
                 "duration": duration,
                 "paused": paused,
                 "volume": volume,
+                "keep_playing": self._keep_playing,
             })
 
-    def _maybe_advance(self):
-        """Called from the poll loop when mpv just went idle. If keep-playing
-        is on and there's a next file in the current folder queue, load it."""
-        with self._lock:
-            keep_playing = self._state["keep_playing"]
-            has_next = (
-                self._queue_files
-                and 0 <= self._queue_index + 1 < len(self._queue_files)
-            )
-            if keep_playing and has_next:
-                self._queue_index += 1
-                next_file = self._queue_files[self._queue_index]
-            else:
-                next_file = None
-
-        if next_file:
-            try:
-                self._client.command("loadfile", next_file, "replace")
-            except MpvIPCError as exc:
-                log.warning("auto-advance loadfile failed: %s", exc)
-
     # -- public read API ---------------------------------------------------
 
     def get_status(self):
         with self._lock:
-            state = dict(self._state)
+            return dict(self._state)
-            state["keep_playing"] = self._state["keep_playing"]
+
-        return state
+    # -- helpers -----------------------------------------------------------
+
+    def _play_playlist(self, files, start_index):
+        """Load `files` into mpv's playlist (folder order) and start at
+        start_index. mpv advances through them on its own from here on."""
+        # `loadfile ... replace` starts a fresh playlist with the first file;
+        # append the rest to rebuild the folder in order, then jump to the
+        # chosen entry so the playlist matches the folder exactly.
+        self._mpv.command("loadfile", files[0], "replace")
+        for f in files[1:]:
+            self._mpv.command("loadfile", f, "append")
+        if start_index > 0:
+            self._mpv.set_property("playlist-pos", start_index)
+        self._apply_repeat()
+
+    def _apply_repeat(self):
+        """Set mpv's playlist loop to match keep-playing."""
+        self._mpv.set_property("loop-playlist", "inf" if self._keep_playing else "no")
 
     # -- public command API (called from Flask routes) ---------------------
 
     def play_file(self, path):
-        self._client.command("loadfile", path, "replace")
+        # Queue the whole containing folder so playback continues through the
-        # Build the auto-advance queue from the containing folder, positioned
+        # rest of it, starting at the chosen file.
-        # at the file just started -- so "keep playing" continues through the
-        # rest of the folder even when you start from the middle.
         folder = os.path.dirname(path)
         files = list_video_files(folder, self.video_extensions)
         try:
             index = files.index(path)
         except ValueError:
-            # played file isn't in the folder listing (unusual) -- queue just it
             files = [path]
             index = 0
-        with self._lock:
+        self._play_playlist(files, index)
-            self._queue_folder = folder
-            self._queue_files = files
-            self._queue_index = index
 
     def play_folder(self, folder_path):
         files = list_video_files(folder_path, self.video_extensions)
         if not files:
             raise ValueError(f"no video files in {folder_path}")
-        self._client.command("loadfile", files[0], "replace")
+        self._play_playlist(files, 0)
-        with self._lock:
-            self._queue_folder = folder_path
-            self._queue_files = files
-            self._queue_index = 0
 
     def playpause(self):
-        self._client.command("cycle", "pause")
+        if self._has_media():
+            self._mpv.command("cycle", "pause")
+
+    def next(self):
+        if self._has_media():
+            self._mpv.command("playlist-next", "weak")
+
+    def previous(self):
+        if self._has_media():
+            self._mpv.command("playlist-prev", "weak")
 
     def seek(self, offset_seconds):
-        self._client.command("seek", offset_seconds, "relative")
+        if self._has_media():
+            self._mpv.command("seek", int(offset_seconds), "relative")
+
+    def seek_to(self, position_seconds):
+        """Seek to an absolute position (seconds from the start) -- used by the
+        draggable progress bar."""
+        if self._has_media():
+            pos = max(0, int(position_seconds))
+            self._mpv.command("seek", pos, "absolute")
 
     def set_volume(self, value):
         value = max(0, min(100, value))
-        self._client.set_property("volume", value)
+        self._mpv.set_property("volume", value)
 
     def set_keep_playing(self, enabled):
         with self._lock:
-            self._state["keep_playing"] = bool(enabled)
+            self._keep_playing = bool(enabled)
+            self._state["keep_playing"] = self._keep_playing
+        self._apply_repeat()

mediapi/routes/api_routes.py

@@ -1,7 +1,7 @@
 from flask import Blueprint, current_app, jsonify, request
 
+from ..mpv import MpvError
 from ..media import PathError, list_directory, resolve_path
-from ..mpv_ipc import MpvIPCError
 
 bp = Blueprint("api", __name__, url_prefix="/api")
 
@@ -42,7 +42,7 @@ def play():
             player.play_folder(resolved)
     except ValueError as exc:
         return jsonify({"error": str(exc)}), 400
-    except MpvIPCError as exc:
+    except MpvError as exc:
         return jsonify({"error": f"player unavailable: {exc}"}), 503
 
     return jsonify({"ok": True})
@@ -52,7 +52,25 @@ def play():
 def playpause():
     try:
         current_app.player.playpause()
-    except MpvIPCError as exc:
+    except MpvError as exc:
+        return jsonify({"error": f"player unavailable: {exc}"}), 503
+    return jsonify({"ok": True})
+
+
+@bp.route("/control/next", methods=["POST"])
+def next_clip():
+    try:
+        current_app.player.next()
+    except MpvError as exc:
+        return jsonify({"error": f"player unavailable: {exc}"}), 503
+    return jsonify({"ok": True})
+
+
+@bp.route("/control/previous", methods=["POST"])
+def previous_clip():
+    try:
+        current_app.player.previous()
+    except MpvError as exc:
         return jsonify({"error": f"player unavailable: {exc}"}), 503
     return jsonify({"ok": True})
 
@@ -67,7 +85,22 @@ def seek():
 
     try:
         current_app.player.seek(offset)
-    except MpvIPCError as exc:
+    except MpvError as exc:
+        return jsonify({"error": f"player unavailable: {exc}"}), 503
+    return jsonify({"ok": True})
+
+
+@bp.route("/control/seekto", methods=["POST"])
+def seekto():
+    body = request.get_json(force=True, silent=True) or {}
+    try:
+        position = float(body.get("position"))
+    except (TypeError, ValueError):
+        return jsonify({"error": "expected {position: seconds}"}), 400
+
+    try:
+        current_app.player.seek_to(position)
+    except MpvError as exc:
         return jsonify({"error": f"player unavailable: {exc}"}), 503
     return jsonify({"ok": True})
 
@@ -82,7 +115,7 @@ def volume():
 
     try:
         current_app.player.set_volume(value)
-    except MpvIPCError as exc:
+    except MpvError as exc:
         return jsonify({"error": f"player unavailable: {exc}"}), 503
     return jsonify({"ok": True})
 

mediapi/static/css/style.css

@@ -135,18 +135,26 @@ html, body {
 
 .transport-row {
   display: flex;
-  gap: 0.5rem;
+  gap: 0.4rem;
   margin: 1rem 0;
 }
 
 .transport-row button {
   flex: 1;
-  padding: 0.8rem;
+  padding: 0.8rem 0.3rem;
   border-radius: 6px;
   border: 1px solid #444;
   background: #1c1c1c;
   color: #eee;
   font-size: 1rem;
+  white-space: nowrap;
+}
+
+/* Prev/Next are compact icon buttons; the middle three carry the labels. */
+#btn-prev, #btn-next {
+  flex: 0 0 auto;
+  min-width: 2.6rem;
+  font-size: 1.2rem;
 }
 
 .volume-row {

mediapi/static/js/app.js

@@ -3,6 +3,9 @@
 
   let currentPath = null; // null = top-level media roots
   let volumeDebounce = null;
+  let seeking = false; // user is dragging the progress bar
+  let seekSuppressUntil = 0; // ignore poll updates briefly after a seek
+  let keepSuppressUntil = 0; // ignore poll updates briefly after toggling keep-playing
 
   const el = (id) => document.getElementById(id);
 
@@ -102,17 +105,23 @@
       if (!online) return;
 
       el("now-playing").textContent = data.filename || "—";
-      el("time-pos").textContent = formatTime(data.position);
       el("time-dur").textContent = formatTime(data.duration);
 
       const slider = el("seek-slider");
       slider.max = data.duration || 0;
+      // Don't fight the user while they're dragging, or right after a seek
+      // (the player takes a beat to report the new position).
+      if (!seeking && Date.now() > seekSuppressUntil) {
         slider.value = data.position || 0;
+        el("time-pos").textContent = formatTime(data.position);
+      }
 
       if (document.activeElement !== el("volume-slider")) {
         el("volume-slider").value = data.volume || 0;
       }
+      if (Date.now() > keepSuppressUntil) {
         el("keep-playing-checkbox").checked = !!data.keep_playing;
+      }
     });
   }
 
@@ -120,6 +129,14 @@
     api("/api/control/playpause", { method: "POST" });
   });
 
+  el("btn-prev").addEventListener("click", () => {
+    api("/api/control/previous", { method: "POST" });
+  });
+
+  el("btn-next").addEventListener("click", () => {
+    api("/api/control/next", { method: "POST" });
+  });
+
   el("btn-back30").addEventListener("click", () => {
     api("/api/control/seek", { method: "POST", body: JSON.stringify({ offset: -30 }) });
   });
@@ -128,6 +145,20 @@
     api("/api/control/seek", { method: "POST", body: JSON.stringify({ offset: 30 }) });
   });
 
+  // Drag the progress bar to seek. 'input' fires while dragging (live label),
+  // 'change' fires on release (send the absolute seek).
+  el("seek-slider").addEventListener("input", (e) => {
+    seeking = true;
+    el("time-pos").textContent = formatTime(Number(e.target.value));
+  });
+
+  el("seek-slider").addEventListener("change", (e) => {
+    const pos = Number(e.target.value);
+    seeking = false;
+    seekSuppressUntil = Date.now() + 1200;
+    api("/api/control/seekto", { method: "POST", body: JSON.stringify({ position: pos }) });
+  });
+
   el("volume-slider").addEventListener("input", (e) => {
     clearTimeout(volumeDebounce);
     const value = e.target.value;
@@ -137,6 +168,7 @@
   });
 
   el("keep-playing-checkbox").addEventListener("change", (e) => {
+    keepSuppressUntil = Date.now() + 1500;
     api("/api/control/keep-playing", {
       method: "POST",
       body: JSON.stringify({ enabled: e.target.checked }),

mediapi/templates/index.html

@@ -27,13 +27,15 @@
         <p id="now-playing" class="filename">&mdash;</p>
         <div class="progress-row">
           <span id="time-pos">0:00</span>
-          <input id="seek-slider" type="range" min="0" max="0" step="1" disabled>
+          <input id="seek-slider" type="range" min="0" max="0" step="1">
           <span id="time-dur">0:00</span>
         </div>
         <div class="transport-row">
+          <button id="btn-prev" title="Previous clip">&#9198;</button>
           <button id="btn-back30">&laquo; 30</button>
           <button id="btn-playpause">Play/Pause</button>
           <button id="btn-fwd30">30 &raquo;</button>
+          <button id="btn-next" title="Next clip">&#9197;</button>
         </div>
         <div class="volume-row">
           <span>Vol</span>

scripts/mediapi-session.sh

@@ -1,78 +0,0 @@
-#!/bin/sh
-#
-# mediapi X session -- the X client launched by xinit from mediapi-mpv.service.
-#
-# Mirrors every extra HDMI output onto the first, then runs ONE fullscreen mpv.
-#
-# Why an X server at all (we used to run mpv straight on DRM/KMS for fast boot):
-# DRM "master" is exclusive per card. The Pi 4's two HDMI connectors live on a
-# single vc4 card, so two independent mpv processes cannot both modeset -- the
-# second gets "Failed to acquire DRM master: Permission denied" and shows
-# nothing. A single X server is the one DRM master and drives BOTH connectors;
-# `xrandr --same-as` clones the first output's framebuffer onto the others, so
-# one mpv appears on every screen. See git history for the full diagnosis.
-#
-set -u
-
-RUNTIME_DIR="${MEDIAPI_RUNTIME_DIR:-/run/mediapi}"
-SOCKET="${MEDIAPI_MPV_SOCKET:-$RUNTIME_DIR/mpv.sock}"
-
-# Always-on car display: never blank or DPMS-off.
-xset -dpms 2>/dev/null || true
-xset s off 2>/dev/null || true
-
-connected() { xrandr --query 2>/dev/null | awk '/ connected/{print $1}'; }
-
-# Cold-boot race: the second HDMI connector may not be probed as "connected"
-# when X starts. Wait for connected outputs to appear, then let the set settle
-# so a screen that lights up a beat later is still mirrored (bounded so a
-# genuinely single-screen setup doesn't hang the boot).
-deadline=$(( $(date +%s) + 30 ))
-outs="$(connected)"
-while [ -z "$outs" ] && [ "$(date +%s)" -lt "$deadline" ]; do
-  sleep 1
-  outs="$(connected)"
-done
-
-stable=0
-settle_end=$(( $(date +%s) + 8 ))
-while [ "$(date +%s)" -lt "$settle_end" ]; do
-  sleep 1
-  cur="$(connected)"
-  if [ "$cur" != "$outs" ]; then
-    outs="$cur"
-    stable=0
-  else
-    stable=$(( stable + 1 ))
-    [ "$stable" -ge 2 ] && break
-  fi
-done
-
-primary=""
-rest=""
-for o in $outs; do
-  if [ -z "$primary" ]; then primary="$o"; else rest="$rest $o"; fi
-done
-echo "mediapi-session: connected outputs:$outs (primary=${primary:-none})"
-
-for o in $rest; do
-  echo "mediapi-session: mirroring $o onto $primary"
-  xrandr --output "$o" --same-as "$primary" || true
-done
-
-# Single mpv, on X (so one DRM master drives every mirrored connector). Carries
-# audio and the app's IPC socket; the app talks only to this one socket now.
-# hwdec=v4l2m2m-copy uses the Pi's hardware H.264/HEVC decoder (falls back to
-# software for codecs it can't handle). Roughly a third of the CPU of software
-# decoding 1080p -- important for an always-on player in a warm car. The single
-# mpv has the HW decoder to itself now, so there's no contention.
-exec mpv \
-  --idle=yes \
-  --vo=gpu-next \
-  --gpu-context=x11egl \
-  --hwdec=v4l2m2m-copy \
-  --fullscreen \
-  --no-terminal \
-  --keep-open=no \
-  --input-ipc-server="$SOCKET" \
-  --ao=alsa

scripts/mediapi-watchdog.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+#
+# mediapi-watchdog -- reboot the Pi if the mpv player wedges.
+#
+# Guards against the failure seen 2026-07-09: a kernel oops left the player
+# stuck in uninterruptible (D) state while the rest of the box -- systemd, SSH,
+# the Flask app -- stayed alive and responsive. A plain systemd/hardware
+# watchdog only fires on a TOTAL system hang, so it would NOT have caught that
+# partial wedge. Instead we ping mpv over its JSON IPC socket; if mpv stays
+# unresponsive for ~3 minutes we force a reboot, turning a dead-all-night wedge
+# into a ~30s auto-recovery.
+#
+# Runs as root (needs to force a reboot). Installed + enabled by install.sh.
+set -u
+
+SOCK="${MEDIAPI_MPV_SOCKET:-/run/mediapi/mpv.sock}"
+INTERVAL="${MEDIAPI_WATCHDOG_INTERVAL:-30}"        # seconds between checks
+FAILS_TO_REBOOT="${MEDIAPI_WATCHDOG_FAILS:-6}"     # consecutive fails -> reboot (~3 min)
+PING_TIMEOUT="${MEDIAPI_WATCHDOG_PING_TIMEOUT:-6}" # per-check hard timeout
+DRYRUN="${MEDIAPI_WATCHDOG_DRYRUN:-}"              # non-empty: log instead of rebooting
+
+# Return 0 iff mpv replies to a JSON IPC command within PING_TIMEOUT. A player
+# wedged in D-state accepts the socket connect but never replies, so the recv
+# blocks and `timeout` trips it -- exactly the case we want to catch.
+ping_mpv() {
+  timeout "$PING_TIMEOUT" python3 - "$SOCK" <<'PY'
+import socket, json, sys
+try:
+    s = socket.socket(socket.AF_UNIX); s.settimeout(4); s.connect(sys.argv[1])
+    s.sendall(b'{"command":["get_property","mpv-version"],"request_id":1}\n')
+    buf = b""
+    while b"\n" not in buf:
+        chunk = s.recv(4096)
+        if not chunk:
+            sys.exit(1)
+        buf += chunk
+    for line in buf.decode(errors="replace").splitlines():
+        m = json.loads(line)
+        if m.get("request_id") == 1:
+            sys.exit(0 if m.get("error") == "success" else 1)
+    sys.exit(1)
+except Exception:
+    sys.exit(1)
+PY
+}
+
+do_reboot() {
+  if [ -n "$DRYRUN" ]; then
+    echo "mediapi-watchdog: DRYRUN -- would reboot now" >&2
+    return
+  fi
+  # Best-effort clean reboot first; fall back to SysRq, which reboots at the
+  # kernel level even when userspace is wedged in D-state (the case we guard).
+  sync &
+  systemctl reboot -ff &
+  sleep 12
+  echo 1 > /proc/sys/kernel/sysrq 2>/dev/null || true
+  echo b > /proc/sysrq-trigger 2>/dev/null || true
+}
+
+echo "mediapi-watchdog: watching $SOCK (reboot after ${FAILS_TO_REBOOT}x${INTERVAL}s unresponsive)" >&2
+fails=0
+while true; do
+  if ping_mpv; then
+    fails=0
+  else
+    fails=$((fails + 1))
+    echo "mediapi-watchdog: mpv ping FAILED ($fails/$FAILS_TO_REBOOT)" >&2
+    if [ "$fails" -ge "$FAILS_TO_REBOOT" ]; then
+      echo "mediapi-watchdog: mpv unresponsive ~$((INTERVAL * FAILS_TO_REBOOT))s -- rebooting" >&2
+      do_reboot
+      fails=0
+    fi
+  fi
+  sleep "$INTERVAL"
+done

systemd/mediapi-mpv.service.template

@@ -1,30 +1,39 @@
 [Unit]
-Description=mediapi player (X kiosk: one mpv mirrored across all HDMI outputs)
+Description=mpv video player (KMS/DRM -- the actual player)
-# Wait until udev has settled so the DRM/HDMI devices (/dev/dri/*) exist before
+# Needs the DRM/HDMI + sound devices present.
-# X tries to grab them. Without this a cold-boot race can leave X unable to find
+After=local-fs.target systemd-udev-settle.service sound.target
-# a screen. (systemd-udev-settle is deprecated but still the simplest reliable
-# gate here; the session script additionally waits for connectors to appear.)
-After=local-fs.target systemd-udev-settle.service
 Wants=systemd-udev-settle.service
+# Keep a login getty off the primary display so nothing else claims tty1.
+Conflicts=getty@tty1.service
 
 [Service]
-Type=simple
 User=${MEDIAPI_USER}
-# video+render: GPU/DRM access. input: evdev under X. tty: own the VT for X.
+# mpv on KMS/DRM needs: video+render (GPU/DRM), input (remotes/keyboard), audio
-SupplementaryGroups=video render input tty
+# (HDMI/ALSA). It becomes DRM master simply as the first/only DRM client on the
-# A controlling tty so the X server can take over VT 7.
+# seat -- no PAM login session and no elevated capabilities required, provided
-TTYPath=/dev/tty7
+# nothing else is already holding the GPU. (An older Kodi-based deploy DID hold
-StandardInput=tty
+# it; install.sh tears any leftover Kodi down before starting this.)
+SupplementaryGroups=video render input audio
+# Create /run/mediapi (owned by this user) for the IPC socket the app connects to.
+RuntimeDirectory=mediapi
+StandardInput=null
 StandardOutput=journal
 StandardError=journal
-RuntimeDirectory=mediapi
+# --idle keeps mpv running with no file loaded (holds the playlist between clips
-RuntimeDirectoryMode=0770
+# and after the last one), so the service stays up and the app can always reach
-# xinit starts the X server on VT 7 and runs the session script as its client.
+# the socket. Playback renders straight on KMS.
-# The session mirrors the HDMI outputs (single DRM master) and execs one mpv.
+ExecStart=/usr/bin/mpv \
-# Non-root X is permitted via /etc/X11/Xwrapper.config (installed by install.sh).
+  --idle=yes \
-ExecStart=/usr/bin/xinit ${PROJECT_DIR}/scripts/mediapi-session.sh -- :0 vt7 -nolisten tcp -keeptty
+  --input-ipc-server=/run/mediapi/mpv.sock \
+  --no-terminal \
+  --no-input-default-bindings \
+  --fullscreen \
+  --force-window=yes \
+  --keep-open=no \
+  --vo=gpu --gpu-context=drm --hwdec=auto \
+  --ao=alsa --audio-device=alsa/hdmi:CARD=vc4hdmi0,DEV=0
 Restart=on-failure
-RestartSec=2
+RestartSec=5
 
 [Install]
 WantedBy=multi-user.target

systemd/mediapi-watchdog.service.template

@@ -0,0 +1,15 @@
+[Unit]
+Description=MediaPi watchdog -- reboots the Pi if the mpv player wedges
+After=mediapi-mpv.service
+Wants=mediapi-mpv.service
+
+[Service]
+Type=simple
+# Runs as root (no User=): must be able to force a reboot, including via SysRq,
+# to recover a box whose player is wedged in uninterruptible D-state.
+ExecStart=${PROJECT_DIR}/scripts/mediapi-watchdog.sh
+Restart=always
+RestartSec=10
+
+[Install]
+WantedBy=multi-user.target