Refacor: Use JSON outputs of command line utils as much as possible and

generalize sysfs and subprocess code

AGENTS.md

@@ -46,13 +46,20 @@ agent's own shell command line and kills the session.
 - `app/collect/*` — collectors (cpu/mem/gpu/disks/procs/net/power) read
   psutil + sysfs; `app/sampling.py` runs them every `DASH_SAMPLE_INTERVAL`
   (default 2 s) into an in-memory ring buffer (`app/state.py`).
+- `app/utils/` — shared helpers: `subprocess.py` (`run`/`run_async` return
+  `(rc, stdout, stderr)` and never raise — missing binary or timeout is
+  rc -1 with the reason in stderr; `run_json*` variants parse stdout as
+  JSON), `sysfs.py` (`read_str`/`read_int`/`read_float`), `gpu.py`
+  (`shorten`), `window.py` (the `/api/history` windowing), `systemd.py`
+  (unit listing/detail/actions; `list-units`/`list-unit-files` use
+  `--output=json`, needs systemd ≥ ~246, `show` has no JSON).
 - `app/routers/*` — each tab endpoint is an idempotent GET returning an htmx
   HTML fragment; templates live in `templates/` and self-poll via
   `hx-get` + `hx-trigger="every Ns"` + `hx-swap="outerHTML"`.
 - `templates/*.html` auto-reload on file change — no restart needed for
   template-only edits. Python changes require a restart.
-- `app/systemd/units.py` — systemd unit listing/detail/actions;
+- `app/journal.py` — `journalctl -o json` parser (one JSON object per line)
-  `app/journal.py` — `journalctl -o export` parser with cursors.
+  with cursors.
 - `app/plugins/` — `base.Plugin` (optional `open`/`close` lifecycle hooks run
   from app lifespan) + llamacpp plugin (talks to a router-mode `llama-server`
   on port 8080) + sleep plugin (lists block-mode `systemd-inhibit` locks;
@@ -60,7 +67,7 @@ agent's own shell command line and kills the session.
   while the UI switch is on, reaps stale locks by `who` marker on startup)
   + lact plugin (shells out to `lact cli`: per-GPU profile dropdown with
   set/reload, active profile polled every 5 s, GPU names shortened with
-  `app/collect/gpu.py:shorten` like the overview card).
+  `app/utils/gpu.py:shorten` like the overview card).
 
 ## Conventions
 
@@ -79,9 +86,15 @@ agent's own shell command line and kills the session.
 
 - Jinja autoescape renders `↓` as literal text — use literal unicode
   (e.g. `↓`) in templates.
-- `journalctl -o export` output contains NUL bytes (grep treats it as
+- `journalctl` is queried with `-o json` on purpose: the old `-o export`
-  binary); journalctl rejects negated matches (`!`/`!=`) — filter entries in
+  output contains NUL bytes (grep treats it as binary) and multi-line
+  values need continuation-line handling, while JSON escapes both.
+  journalctl still rejects negated matches (`!`/`!=`) — filter entries in
   Python instead.
+- `nvidia-smi --format=json` keys are underscored and **values are
+  strings**; `lspci` has no JSON (use the locale-stable `-mm`
+  double-quoted format); `systemctl show`, `systemctl is-system-running`,
+  `iw`, and `lact cli` have no JSON output at all.
 - psutil gotchas: there is no `psutil.AF_INET` (use `socket`);
   `net_if_addrs()` / `net_if_stats()` take no arguments;
   `sensors_battery().power_plugged` can be `None` — use

app/collect/cpu.py

@@ -3,27 +3,12 @@ import glob
 import psutil
 
 from app.sample import Sample
+from app.utils import sysfs
 
 _temp_path: str | None = None
 _temp_checked = False
 
 
-def _read(path: str) -> str | None:
-    """Read a sysfs file, returning its stripped contents.
-
-    Args:
-        path: path under /sys.
-
-    Returns:
-        The file contents, or None if it cannot be read.
-    """
-    try:
-        with open(path) as f:
-            return f.read().strip()
-    except OSError:
-        return None
-
-
 def _find_temp_path() -> str | None:
     """Find the sysfs file reporting CPU temperature, in millidegrees.
 
@@ -36,13 +21,13 @@ def _find_temp_path() -> str | None:
         The sysfs file to read, or None if no suitable sensor exists.
     """
     for hwmon in sorted(glob.glob("/sys/class/hwmon/hwmon*")):
-        name = (_read(f"{hwmon}/name") or "").lower()
+        name = (sysfs.read_str(f"{hwmon}/name") or "").lower()
         if name in ("k10temp", "coretemp", "cpu_thermal"):
             for t in sorted(glob.glob(f"{hwmon}/temp*_input")):
                 return t
             return None
     for zone in sorted(glob.glob("/sys/class/thermal/thermal_zone*")):
-        if (_read(f"{zone}/type") or "").lower() == "acpitz":
+        if (sysfs.read_str(f"{zone}/type") or "").lower() == "acpitz":
             return f"{zone}/temp"
     return None
 
@@ -62,14 +47,10 @@ def temp() -> float | None:
         _temp_path = _find_temp_path()
     if _temp_path is None:
         return None
-    v = _read(_temp_path)
+    v = sysfs.read_float(_temp_path)
-    if not v:
+    if v is None:
         return None
-    try:
+    return round(v / 1000.0, 1)
-        n = float(v)
-    except ValueError:
-        return None
-    return round(n / 1000.0, 1)
 
 
 def prime() -> None:

app/collect/gpu.py

@@ -1,63 +1,24 @@
 import glob
 import re
 import shutil
-import subprocess
+from typing import Any, cast
 
 from app.sample import Sample
+from app.utils import sysfs
+from app.utils.gpu import shorten
+from app.utils.subprocess import run, run_json
 
 _name_cache: str | None = None
 
-
+_LSPCI_QUOTED = re.compile(r'"([^"]*)"')
-def _read(path: str) -> str | None:
-    """Read a sysfs file, returning its stripped contents.
-
-    Args:
-        path: path under /sys.
-
-    Returns:
-        The file contents, or None if it cannot be read.
-    """
-    try:
-        with open(path) as f:
-            return f.read().strip()
-    except OSError:
-        return None
-
-
-def shorten(name: str) -> str:
-    """Shorten a raw GPU device name (lspci / lact) for display.
-
-    Strips a trailing "(rev ...)" marker, then reformats by bracket
-    group: a name like "Renoir [Radeon Vega Series / ...]" becomes
-    "Renoir (Radeon Vega Series)"; a name with two or more groups (typical
-    for unbound PCI IDs, e.g. "[1002] Device [1586]") becomes
-    "first-group middle-text (last-group)"; anything else is truncated to
-    50 characters.
-
-    Args:
-        name: raw device name from lspci or lact.
-
-    Returns:
-        A display-friendly name.
-    """
-    name = re.sub(r"\s*\(rev.*\)$", "", name).strip()
-    groups = re.findall(r"\[([^\]]+)\]", name)
-    if len(groups) >= 2:
-        brand = groups[0]
-        series = groups[-1].split(" / ")[0]
-        model = name.split("]", 1)[1].split("[", 1)[0].strip()
-        return f"{brand} {model} ({series})".strip()
-    if len(groups) == 1:
-        series = groups[0].split(" / ")[0]
-        model = name.split("[", 1)[0].strip()
-        return f"{model} ({series})".strip()
-    return name[:50]
 
 
 def _gpu_name() -> str:
     """Resolve the display GPU name, cached for the process lifetime.
 
-    Runs `lspci` once and takes the first VGA / 3D-controller device name,
+    Runs `lspci -mm` once (stable machine-readable format, one line per
+    device with double-quoted fields: slot, class, vendor, device, ...)
+    and takes the vendor + device of the first VGA / 3D-controller line,
     shortened with shorten(). Falls back to "GPU" if lspci is missing or
     no matching device line is found.
 
@@ -68,16 +29,13 @@ def _gpu_name() -> str:
     if _name_cache is None:
         _name_cache = "GPU"
         if shutil.which("lspci"):
-            try:
+            rc, out, _err = run(["lspci", "-mm"], timeout=5)
-                out = subprocess.run(
+            if rc == 0:
-                    ["lspci"], capture_output=True, text=True, timeout=5, check=False
-                ).stdout
                 for line in out.splitlines():
-                    if "VGA" in line or "3D controller" in line:
+                    f = _LSPCI_QUOTED.findall(line)
-                        _name_cache = shorten(line.split(":", 2)[-1].strip())
+                    if len(f) >= 3 and ("VGA" in f[0] or "3D controller" in f[0]):
+                        _name_cache = shorten(f"{f[1]} {f[2]}")
                         break
-            except (OSError, subprocess.SubprocessError):
-                pass
     return _name_cache
 
 
@@ -106,20 +64,14 @@ def _amd(s: Sample) -> bool:
     temps: list[float] = []
     for busy_path in devices:
         dev = busy_path.rsplit("/", 1)[0]
-        try:
+        busy_sum += sysfs.read_int(busy_path) or 0
-            busy_sum += int(_read(busy_path) or 0)
         count += 1
-        except ValueError:
+        vram_used += sysfs.read_int(f"{dev}/mem_info_vram_used") or 0
-            continue
+        vram_total += sysfs.read_int(f"{dev}/mem_info_vram_total") or 0
-        vram_used += int(_read(f"{dev}/mem_info_vram_used") or 0)
-        vram_total += int(_read(f"{dev}/mem_info_vram_total") or 0)
         for hwmon in glob.glob(f"{dev}/hwmon/hwmon*"):
-            t = _read(f"{hwmon}/temp1_input")
+            t = sysfs.read_int(f"{hwmon}/temp1_input")
-            if t:
+            if t is not None:
-                try:
+                temps.append(t / 1000.0)
-                    temps.append(int(t) / 1000.0)
-                except ValueError:
-                    pass
     if count == 0:
         return False
     s.gpu = round(busy_sum / count, 1)
@@ -134,9 +86,11 @@ def _amd(s: Sample) -> bool:
 def _nvidia(s: Sample) -> bool:
     """Fill GPU fields by querying nvidia-smi.
 
-    Runs `nvidia-smi --query-gpu=...` (5 s timeout) and parses the
+    Runs `nvidia-smi --query-gpu=... --format=json` (5 s timeout) and
-    CSV: busy percent averaged across GPUs, VRAM summed (MiB converted to
+    parses the JSON array (keys are underscored, values strings): busy
-    bytes), temperature the hottest GPU, name from the first line.
+    percent averaged across GPUs, VRAM summed (MiB converted to bytes),
+    temperature the hottest GPU, name from the first GPU. JSON keeps
+    names with commas intact, which the old CSV format split on.
 
     Args:
         s: sample to fill.
@@ -146,38 +100,35 @@ def _nvidia(s: Sample) -> bool:
     """
     if not shutil.which("nvidia-smi"):
         return False
-    try:
+    data, _err = run_json(
-        out = subprocess.run(
         [
             "nvidia-smi",
             "--query-gpu=utilization.gpu,memory.used,memory.total,temperature.gpu,name",
-                "--format=csv,noheader,nounits",
+            "--format=json",
         ],
-            capture_output=True,
-            text=True,
         timeout=5,
-            check=True,
+    )
-        ).stdout
+    if not isinstance(data, list) or not data:
-    except (OSError, subprocess.SubprocessError):
-        return False
-    lines = [l for l in out.splitlines() if l.strip()]
-    if not lines:
         return False
+    rows = cast("list[dict[str, Any]]", data)
     busy = used = total = 0
     temp = 0
-    for line in lines:
+    count = 0
-        parts = [p.strip() for p in line.split(",")]
+    for e in rows:
         try:
-            busy += int(parts[0])
+            busy += int(e["utilization_gpu"])
-            used += int(parts[1])
+            used += int(e["memory_used"])
-            total += int(parts[2])
+            total += int(e["memory_total"])
-            temp = max(temp, int(parts[3]))
+            temp = max(temp, int(e["temperature_gpu"]))
-        except ValueError:
+            count += 1
+        except (ValueError, TypeError, KeyError):
             continue
-    name = lines[0].split(",")[-1].strip()
+    if count == 0:
+        return False
+    name = str(rows[0].get("name") or "").strip() or "GPU"
     vram_used = used * 1024 * 1024
     vram_total = total * 1024 * 1024
-    s.gpu = round(busy / len(lines), 1)
+    s.gpu = round(busy / count, 1)
     s.vram_used = vram_used
     s.vram_total = vram_total
     s.vram_pct = round(vram_used / vram_total * 100, 1) if vram_total else None

app/collect/net.py

@@ -2,12 +2,13 @@ import glob
 import re
 import shutil
 import socket
-import subprocess
 import time
 from typing import Any
 
 import psutil
 
+from app.utils.subprocess import run
+
 _wifi_cache: dict[str, tuple[float, str | None]] = {}
 _WIFI_TTL = 15.0
 _SSID_RE = re.compile(r"SSID:\s+(\S.*)")
@@ -44,15 +45,11 @@ def _ssid(iface: str) -> str | None:
         return hit[1]
     ssid: str | None = None
     if shutil.which("iw"):
-        try:
+        rc, out, _err = run(["iw", "dev", iface, "link"], timeout=3)
-            out = subprocess.run(
+        if rc == 0:
-                ["iw", "dev", iface, "link"], capture_output=True, text=True, timeout=3, check=False
-            ).stdout
             m = _SSID_RE.search(out)
             if m:
                 ssid = m.group(1).strip().strip('"') or None
-        except (OSError, subprocess.SubprocessError):
-            pass
     _wifi_cache[iface] = (now, ssid)
     return ssid
 

app/collect/power.py

@@ -1,26 +1,11 @@
 import glob
 
 from app.sample import Sample
+from app.utils import sysfs
 
 _PS = "/sys/class/power_supply"
 
 
-def _read(path: str) -> str | None:
-    """Read a sysfs file, returning its stripped contents.
-
-    Args:
-        path: path under /sys.
-
-    Returns:
-        The file contents, or None if it cannot be read.
-    """
-    try:
-        with open(path) as f:
-            return f.read().strip()
-    except OSError:
-        return None
-
-
 def _supplies() -> list[tuple[str, str]]:
     """List power supplies found under /sys/class/power_supply.
 
@@ -30,7 +15,7 @@ def _supplies() -> list[tuple[str, str]]:
     """
     out: list[tuple[str, str]] = []
     for p in sorted(glob.glob(f"{_PS}/*")):
-        t = _read(f"{p}/type")
+        t = sysfs.read_str(f"{p}/type")
         if t:
             out.append((t.lower(), p))
     return out
@@ -51,22 +36,19 @@ def fill(s: Sample) -> None:
     try:
         supplies = _supplies()
         for t, p in supplies:
-            if t == "battery" and _read(f"{p}/present") == "1":
+            if t == "battery" and sysfs.read_str(f"{p}/present") == "1":
-                cap = _read(f"{p}/capacity")
+                cap = sysfs.read_int(f"{p}/capacity")
                 if cap is not None:
-                    try:
+                    s.battery = cap
-                        s.battery = int(cap)
+                s.battery_status = sysfs.read_str(f"{p}/status")
-                    except ValueError:
-                        pass
-                    s.battery_status = _read(f"{p}/status")
                 break
         for t, p in supplies:
-            if t == "mains" and _read(f"{p}/online") == "1":
+            if t == "mains" and sysfs.read_str(f"{p}/online") == "1":
                 s.ac_online = True
                 break
         if s.ac_online is None:
             for t, p in supplies:
-                if t == "usb" and _read(f"{p}/online") == "1":
+                if t == "usb" and sysfs.read_str(f"{p}/online") == "1":
                     s.ac_online = True
                     break
     except OSError:

app/collect/procs.py

@@ -1,10 +1,11 @@
 import shutil
-import subprocess
 import time
-from typing import Any
+from typing import Any, cast
 
 import psutil
 
+from app.utils.subprocess import run_json
+
 _prev_io: dict[int, tuple[float, float, float]] = {}
 _gpu_procs: dict[int, int] | None = None
 _gpu_probe_t = 0.0
@@ -13,9 +14,10 @@ _gpu_probe_t = 0.0
 def _gpu_per_proc() -> dict[int, int]:
     """Map PID to GPU memory used (MiB) for NVIDIA compute processes.
 
-    Runs `nvidia-smi --query-compute-apps` at most once per 10 seconds
+    Runs `nvidia-smi --query-compute-apps --format=json` at most once per
-    (the probe result is cached). Returns an empty mapping when nvidia-smi
+    10 seconds (the probe result is cached). Returns an empty mapping
-    is missing, which is the case on AMD machines.
+    when nvidia-smi is missing or fails, which is the case on AMD
+    machines.
 
     Returns:
         A pid to used-memory-in-MiB mapping.
@@ -27,27 +29,20 @@ def _gpu_per_proc() -> dict[int, int]:
         return _gpu_procs
     _gpu_probe_t = time.monotonic()
     _gpu_procs = {}
-    try:
+    data, _err = run_json(
-        out = subprocess.run(
         [
             "nvidia-smi",
             "--query-compute-apps=pid,used_memory",
-                "--format=csv,noheader,nounits",
+            "--format=json",
         ],
-            capture_output=True,
-            text=True,
         timeout=5,
-            check=False
+    )
-        ).stdout
+    if isinstance(data, list):
-        for line in out.splitlines():
+        for e in cast("list[dict[str, Any]]", data):
-            parts = [p.strip() for p in line.split(",")]
-            if len(parts) >= 2:
             try:
-                    _gpu_procs[int(parts[0])] = int(parts[1])
+                _gpu_procs[int(e["pid"])] = int(e["used_memory"])
-                except ValueError:
+            except (ValueError, TypeError, KeyError):
                 continue
-    except (OSError, subprocess.SubprocessError):
-        pass
     return _gpu_procs
 
 

app/journal.py

@@ -1,47 +1,40 @@
-import asyncio
+import json
 import re
 from datetime import UTC, datetime
-from typing import Any
+from typing import Any, cast
+
+from app.utils.subprocess import run_async
 
 CURSOR_RE = re.compile(r"^[A-Za-z0-9;:=+./_-]+$")
 LEVELS = {"all": None, "warn": "warning", "err": "err"}
-FIELD_RE = re.compile(r"^([A-Z_][A-Z0-9_]*)=")
 
 
-def parse_export(text: str) -> list[dict[str, Any]]:
+def parse_lines(text: str) -> list[dict[str, Any]]:
-    """Parse `journalctl -o export` output into entry dicts.
+    """Parse `journalctl -o json` output into entry dicts.
 
-    The export format is `KEY=value` lines separated by blank lines; a
+    Each non-empty line is one JSON object. Multi-line messages are
-    line that does not start with an uppercase key is a continuation of
+    embedded as \\n escapes and control characters (e.g. NUL) are
-    the previous value (joined with newlines). Note the raw output can
+    JSON-escaped, so no continuation-line handling is needed — the
-    contain NUL bytes, which callers must tolerate.
+    former -o export format required both.
 
     Args:
-        text: raw `journalctl -o export` output.
+        text: raw `journalctl -o json` output.
 
     Returns:
-        One dict per entry, key to value (multi-line values preserved).
+        One dict per entry; lines that are not valid JSON objects are
+        skipped.
     """
     entries: list[dict[str, Any]] = []
-    cur: dict[str, Any] | None = None
+    for line in text.splitlines():
-    last_key: str | None = None
+        line = line.strip()
-    for raw in text.splitlines():
+        if not line:
-        if raw == "":
-            if cur is not None:
-                entries.append(cur)
-            cur, last_key = None, None
             continue
-        m = FIELD_RE.match(raw)
+        try:
-        if m:
+            e = json.loads(line)
-            if cur is None:
+        except ValueError:
-                cur = {}
+            continue
-            last_key = m.group(1)
+        if isinstance(e, dict):
-            if last_key is not None:
+            entries.append(cast("dict[str, Any]", e))
-                cur[last_key] = raw[m.end():]
-        elif cur is not None and last_key is not None:
-            cur[last_key] += "\n" + raw
-    if cur is not None:
-        entries.append(cur)
     return entries
 
 
@@ -54,7 +47,7 @@ def format_entries(entries: list[dict[str, Any]]) -> list[dict[str, Any]]:
     SYSLOG_IDENTIFIER -> _COMM -> _PID.
 
     Args:
-        entries: dicts from parse_export.
+        entries: dicts from parse_lines.
 
     Returns:
         One row per kept entry with stamp, prio, ident, msg, cursor.
@@ -91,24 +84,20 @@ async def _journalctl(argv: list[str]) -> str:
     """Run a journalctl subprocess and return its stdout.
 
     Args:
-        argv: full command, e.g. ["sudo", "journalctl", "-n", "100"].
+        argv: full command, e.g. ["sudo", "journalctl", "-o", "json", "-n", "100"].
 
     Returns:
         The decoded stdout.
 
     Raises:
-        RuntimeError: if journalctl exits non-zero; the message is its
+        RuntimeError: if journalctl exits non-zero (or cannot be
-            stderr (or "journalctl failed" when stderr is empty).
+            spawned); the message is its stderr (or "journalctl failed"
+            when stderr is empty).
     """
-    proc = await asyncio.create_subprocess_exec(
+    rc, out, err = await run_async(argv)
-        *argv,
+    if rc != 0:
-        stdout=asyncio.subprocess.PIPE,
+        raise RuntimeError(err.strip() or "journalctl failed")
-        stderr=asyncio.subprocess.PIPE,
+    return out
-    )
-    out, err = await proc.communicate()
-    if proc.returncode != 0:
-        raise RuntimeError(err.decode(errors="replace").strip() or "journalctl failed")
-    return out.decode(errors="replace")
 
 
 async def tail(
@@ -121,7 +110,7 @@ async def tail(
 ) -> tuple[list[dict[str, Any]], str | None]:
     """Fetch a recent journal page, newest entries last.
 
-    Runs `sudo journalctl -o export` with the requested filters. A
+    Runs `sudo journalctl -o json` with the requested filters. A
     non-empty cursor is validated against CURSOR_RE before being passed
     as --after-cursor (invalid cursors are silently ignored); level maps
     through LEVELS, the unit name is regex-checked, and the free-text
@@ -145,7 +134,7 @@ async def tail(
         RuntimeError: if journalctl fails (see _journalctl).
     """
     fetch = lines * 2 if hide_sudo else lines
-    args = ["--no-pager", "-o", "export", "-n", str(min(max(fetch, 1), 500))]
+    args = ["--no-pager", "-o", "json", "-n", str(min(max(fetch, 1), 500))]
     lvl = LEVELS.get(level)
     if lvl:
         args += ["-p", lvl]
@@ -157,7 +146,7 @@ async def tail(
         args += ["--after-cursor", cursor]
     text = await _journalctl(["sudo", "journalctl"] + args)
 
-    entries = parse_export(text)
+    entries = parse_lines(text)
     if hide_sudo:
         entries = [e for e in entries if e.get("SYSLOG_IDENTIFIER") != "sudo"]
     entries = format_entries(entries)

app/plugins/lact.py

@@ -6,9 +6,10 @@ from typing import Annotated, Any
 from fastapi import APIRouter, Form
 from fastapi.responses import HTMLResponse
 
-from app.collect.gpu import shorten
 from app.plugins.base import Plugin
 from app.render import render
+from app.utils.gpu import shorten
+from app.utils.subprocess import run_async
 
 router = APIRouter(prefix="/api/plugins/lact", tags=["plugins"])
 
@@ -34,27 +35,10 @@ async def _run(args: list[str], timeout: float) -> tuple[str, str]:
     Returns:
         (stdout, "") on success, else ("", error description).
     """
-    try:
+    rc, out, err = await run_async(["lact", "cli", *args], timeout=timeout)
-        proc = await asyncio.create_subprocess_exec(
+    if rc != 0:
-            "lact", "cli", *args,
+        return "", (err.strip() or f"lact failed (rc={rc})")[:200]
-            stdout=asyncio.subprocess.PIPE,
+    return out, ""
-            stderr=asyncio.subprocess.PIPE,
-        )
-    except FileNotFoundError:
-        return "", "lact not found in PATH"
-    except OSError as e:
-        return "", str(e)[:200]
-    try:
-        out, err = await asyncio.wait_for(proc.communicate(), timeout)
-    except TimeoutError:
-        try:
-            proc.kill()
-        except ProcessLookupError:
-            pass
-        return "", "lact timed out"
-    if proc.returncode != 0:
-        return "", (err.decode(errors="replace").strip() or f"lact failed (rc={proc.returncode})")[:200]
-    return out.decode(errors="replace"), ""
 
 
 def _parse_gpus(out: str) -> list[dict[str, str]]:
@@ -62,7 +46,7 @@ def _parse_gpus(out: str) -> list[dict[str, str]]:
 
     Each line looks like "0: <device> (Renoir [Radeon Vega Series / ...])
     [Integrated]"; the parenthesised name is shortened with
-    app.collect.gpu.shorten, the trailing bracket is the GPU type.
+    app.utils.gpu.shorten, the trailing bracket is the GPU type.
     Non-matching lines are skipped.
 
     Args:

app/plugins/sleep.py

@@ -1,5 +1,4 @@
 import asyncio
-import json
 import os
 import signal
 from typing import Annotated, Any, cast
@@ -9,6 +8,7 @@ from fastapi.responses import HTMLResponse
 
 from app.plugins.base import Plugin
 from app.render import render
+from app.utils.subprocess import run_json_async
 
 router = APIRouter(prefix="/api/plugins/sleep", tags=["plugins"])
 
@@ -31,28 +31,9 @@ async def _list() -> tuple[list[dict[str, Any]], str]:
     Returns:
         (lock entries, "") on success, else ([], error description).
     """
-    try:
+    data, err = await run_json_async(["systemd-inhibit", "--json=short", "--list"], timeout=5)
-        proc = await asyncio.create_subprocess_exec(
+    if err:
-            "systemd-inhibit", "--json=short", "--list",
+        return [], err[:200]
-            stdout=asyncio.subprocess.PIPE,
-            stderr=asyncio.subprocess.PIPE,
-        )
-    except OSError as e:
-        return [], str(e)[:200]
-    try:
-        out, err = await asyncio.wait_for(proc.communicate(), 5)
-    except TimeoutError:
-        try:
-            _ = proc.kill()
-        except ProcessLookupError:
-            pass
-        return [], "systemd-inhibit timed out"
-    if proc.returncode != 0:
-        return [], (err.decode(errors="replace").strip() or f"systemd-inhibit failed (rc={proc.returncode})")[:200]
-    try:
-        data = json.loads(out.decode(errors="replace"))
-    except ValueError:
-        return [], "could not parse systemd-inhibit output"
     if not isinstance(data, list):
         return [], "unexpected systemd-inhibit output"
     items: list[dict[str, Any]] = [e for e in cast("list[Any]", data) if isinstance(e, dict)]

app/routers/overview.py

@@ -1,8 +1,6 @@
 import asyncio
-import math
 import socket
 import time
-from dataclasses import fields
 from typing import Any
 
 import psutil
@@ -13,53 +11,10 @@ from app.collect import net as net_col
 from app.config import get_settings
 from app.render import render, uptime_str
 from app.sample import Sample
+from app.utils.window import window
 
 router = APIRouter(prefix="/api", tags=["overview"])
 
-RowAgg = dict[str, float | int | None]
-
-
-def _window(snap: list[Sample], max_points: int) -> list[tuple[float, dict[str, RowAgg]]]:
-    """Window-average a sample list down to at most `max_points` points.
-
-    The samples are split into consecutive chunks of ceil(n / max_points)
-    and each numeric Sample field is reduced to {avg, min, max} per chunk;
-    whole-number fields (byte counts) stay ints, fractional fields are
-    rounded to 0.1. Each point is stamped with the timestamp of the last
-    sample in its chunk.
-
-    Args:
-        snap: samples oldest first (HistoryStore.snapshot).
-        max_points: maximum number of points to emit.
-
-    Returns:
-        (timestamp, field aggregations) pairs, oldest first.
-    """
-    n = len(snap)
-    w = max(1, math.ceil(n / max_points))
-    out: list[tuple[float, dict[str, RowAgg]]] = []
-    for start in range(0, n, w):
-        chunk = snap[start : start + w]
-        vals: dict[str, list[int | float]] = {}
-        for sample in chunk:
-            for f in fields(sample):
-                if f.name == "ts":
-                    continue
-                v = getattr(sample, f.name)
-                if isinstance(v, (int, float)) and not isinstance(v, bool):
-                    vals.setdefault(f.name, []).append(v)
-        row: dict[str, RowAgg] = {}
-        for k, lst in vals.items():
-            ints = all(isinstance(v, int) for v in lst)
-            avg = sum(lst) / len(lst)
-            row[k] = {
-                "avg": round(avg) if ints else round(avg, 1),
-                "min": min(lst) if ints else round(min(lst), 1),
-                "max": max(lst) if ints else round(max(lst), 1),
-            }
-        out.append((chunk[-1].ts, row))
-    return out
-
 
 @router.get("/overview")
 async def overview(request: Request):
@@ -114,11 +69,11 @@ async def overview(request: Request):
 async def history(request: Request):
     """Serve the ring buffer as chart data (JSON).
 
-    The buffer is window-averaged via _window() down to at most
+    The buffer is window-averaged via app.utils.window.window() down to
-    `chart_max_points` points. Every key seen in any window gets avg/min/
+    at most `chart_max_points` points. Every key seen in any window gets
-    max arrays, and each array is padded with None for windows that lack
+    avg/min/max arrays, and each array is padded with None for windows
-    the key (e.g. the GPU fields before a GPU is detected) so the arrays
+    that lack the key (e.g. the GPU fields before a GPU is detected) so
-    stay aligned with the ts array — the charts rely on that.
+    the arrays stay aligned with the ts array — the charts rely on that.
 
     Args:
         request: FastAPI request (app.state.store).
@@ -126,7 +81,7 @@ async def history(request: Request):
     Returns:
         JSON with ts (unix seconds) and series: key to {avg, min, max}.
     """
-    snap = _window(request.app.state.store.snapshot(), get_settings().chart_max_points)
+    snap = window(request.app.state.store.snapshot(), get_settings().chart_max_points)
     ts = [round(t, 1) for t, _ in snap]
     keys: set[str] = set()
     for _, row in snap:

app/routers/services.py

@@ -5,7 +5,7 @@ from fastapi.responses import HTMLResponse
 
 from app import journal
 from app.render import render
-from app.systemd import units
+from app.utils import systemd
 
 router = APIRouter(prefix="/api/services", tags=["services"])
 
@@ -41,7 +41,7 @@ def _rank(u: dict[str, Any], key: str) -> int:
     returns 0 here.
 
     Args:
-        u: unit row from units.unit_list().
+        u: unit row from systemd.unit_list().
         key: "state" or "enabled".
 
     Returns:
@@ -74,7 +74,7 @@ async def _list_fragment(q: str, sort: str = "name", order: str = "asc", error:
         sort = "name"
     if order not in ("asc", "desc"):
         order = "asc"
-    unit_list = await units.unit_list()
+    unit_list = await systemd.unit_list()
     if q:
         ql = q.lower()
         unit_list = [
@@ -85,7 +85,7 @@ async def _list_fragment(q: str, sort: str = "name", order: str = "asc", error:
         unit_list.sort(key=lambda u: u["name"], reverse=reverse)
     else:
         unit_list.sort(key=lambda u: (_rank(u, sort), u["name"]), reverse=reverse)
-    state = await units.system_state()
+    state = await systemd.system_state()
     return render(
         "services.html",
         units=unit_list,
@@ -116,7 +116,7 @@ async def services(q: str = "", sort: str = "name", order: str = "asc"):
 async def service_detail(unit: str):
     """Render the detail fragment for one service.
 
-    Shows the unit's properties (via units.unit_detail) plus its 15 most
+    Shows the unit's properties (via systemd.unit_detail) plus its 15 most
     recent journal lines. A detail error suppresses the journal fetch and
     is rendered as a banner.
 
@@ -130,7 +130,7 @@ async def service_detail(unit: str):
     props: dict[str, str] = {}
     log: list[dict[str, str]] = []
     try:
-        props = await units.unit_detail(unit)
+        props = await systemd.unit_detail(unit)
     except (ValueError, RuntimeError) as e:
         error = str(e)[:300]
     if not error:
@@ -157,7 +157,7 @@ async def service_action(
 
     Args:
         unit: unit name.
-        action: one of units.ACTIONS.
+        action: one of systemd.ACTIONS.
         q: search filter to keep.
         sort: column to sort by.
         order: "asc" or "desc".
@@ -167,7 +167,7 @@ async def service_action(
     """
     error = None
     try:
-        _ = await units.unit_action(unit, action)
+        _ = await systemd.unit_action(unit, action)
     except ValueError as e:
         error = str(e)
     except RuntimeError as e:

app/systemd/__init__.py

@@ -1,3 +0,0 @@
-from app.systemd import units
-
-__all__ = ["units"]

app/utils/__init__.py

@@ -0,0 +1,3 @@
+from app.utils import gpu, subprocess, systemd, sysfs, window
+
+__all__ = ["gpu", "subprocess", "systemd", "sysfs", "window"]

app/utils/gpu.py

@@ -0,0 +1,31 @@
+import re
+
+
+def shorten(name: str) -> str:
+    """Shorten a raw GPU device name (lspci / lact) for display.
+
+    Strips a trailing "(rev ...)" marker, then reformats by bracket
+    group: a name like "Renoir [Radeon Vega Series / ...]" becomes
+    "Renoir (Radeon Vega Series)"; a name with two or more groups (typical
+    for unbound PCI IDs, e.g. "[1002] Device [1586]") becomes
+    "first-group middle-text (last-group)"; anything else is truncated to
+    50 characters.
+
+    Args:
+        name: raw device name from lspci or lact.
+
+    Returns:
+        A display-friendly name.
+    """
+    name = re.sub(r"\s*\(rev.*\)$", "", name).strip()
+    groups = re.findall(r"\[([^\]]+)\]", name)
+    if len(groups) >= 2:
+        brand = groups[0]
+        series = groups[-1].split(" / ")[0]
+        model = name.split("]", 1)[1].split("[", 1)[0].strip()
+        return f"{brand} {model} ({series})".strip()
+    if len(groups) == 1:
+        series = groups[0].split(" / ")[0]
+        model = name.split("[", 1)[0].strip()
+        return f"{model} ({series})".strip()
+    return name[:50]

app/utils/subprocess.py

@@ -0,0 +1,104 @@
+import asyncio
+import json
+import subprocess
+from collections.abc import Sequence
+from typing import Any
+
+
+def run(cmd: Sequence[str], *, timeout: float | None = None) -> tuple[int, str, str]:
+    """Run a command synchronously and capture its output.
+
+    Args:
+        cmd: program and arguments.
+        timeout: seconds before the child is killed, or None to wait.
+
+    Returns:
+        (returncode, stdout, stderr), both decoded. Spawn failures
+        (missing binary, other OSError) and timeouts are reported as
+        returncode -1 with the reason in stderr instead of raising.
+    """
+    try:
+        proc = subprocess.run(cmd, capture_output=True, timeout=timeout)
+    except FileNotFoundError:
+        return -1, "", f"{cmd[0]} not found in PATH"
+    except subprocess.TimeoutExpired:
+        return -1, "", f"{cmd[0]} timed out"
+    except (OSError, subprocess.SubprocessError) as e:
+        return -1, "", str(e)[:200]
+    return proc.returncode, proc.stdout.decode(errors="replace"), proc.stderr.decode(errors="replace")
+
+
+async def run_async(cmd: Sequence[str], *, timeout: float | None = None) -> tuple[int, str, str]:
+    """Run a command asynchronously and capture its output.
+
+    The child is killed when the timeout expires.
+
+    Args:
+        cmd: program and arguments.
+        timeout: seconds before the child is killed, or None to wait.
+
+    Returns:
+        (returncode, stdout, stderr), both decoded. Spawn failures
+        (missing binary, other OSError) and timeouts are reported as
+        returncode -1 with the reason in stderr instead of raising.
+    """
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            *cmd,
+            stdout=asyncio.subprocess.PIPE,
+            stderr=asyncio.subprocess.PIPE,
+        )
+    except FileNotFoundError:
+        return -1, "", f"{cmd[0]} not found in PATH"
+    except OSError as e:
+        return -1, "", str(e)[:200]
+    try:
+        if timeout is None:
+            out, err = await proc.communicate()
+        else:
+            out, err = await asyncio.wait_for(proc.communicate(), timeout)
+    except TimeoutError:
+        try:
+            proc.kill()
+        except ProcessLookupError:
+            pass
+        return -1, "", f"{cmd[0]} timed out"
+    return proc.returncode or 0, out.decode(errors="replace"), err.decode(errors="replace")
+
+
+def run_json(cmd: Sequence[str], *, timeout: float | None = None) -> tuple[Any, str]:
+    """Run a command synchronously and parse its stdout as JSON.
+
+    Args:
+        cmd: program and arguments.
+        timeout: seconds before the child is killed, or None to wait.
+
+    Returns:
+        (parsed JSON, "") on success, else (None, error description).
+    """
+    rc, out, err = run(cmd, timeout=timeout)
+    if rc != 0:
+        return None, err or f"{cmd[0]} failed (rc={rc})"
+    try:
+        return json.loads(out), ""
+    except ValueError:
+        return None, f"{cmd[0]} returned invalid JSON"
+
+
+async def run_json_async(cmd: Sequence[str], *, timeout: float | None = None) -> tuple[Any, str]:
+    """Run a command asynchronously and parse its stdout as JSON.
+
+    Args:
+        cmd: program and arguments.
+        timeout: seconds before the child is killed, or None to wait.
+
+    Returns:
+        (parsed JSON, "") on success, else (None, error description).
+    """
+    rc, out, err = await run_async(cmd, timeout=timeout)
+    if rc != 0:
+        return None, err or f"{cmd[0]} failed (rc={rc})"
+    try:
+        return json.loads(out), ""
+    except ValueError:
+        return None, f"{cmd[0]} returned invalid JSON"

app/utils/sysfs.py

@@ -0,0 +1,52 @@
+def read_str(path: str) -> str | None:
+    """Read a sysfs file, returning its stripped contents.
+
+    Args:
+        path: path under /sys.
+
+    Returns:
+        The file contents, or None if it cannot be read.
+    """
+    try:
+        with open(path) as f:
+            return f.read().strip()
+    except OSError:
+        return None
+
+
+def read_int(path: str) -> int | None:
+    """Read a sysfs file as an integer.
+
+    Args:
+        path: path under /sys.
+
+    Returns:
+        The parsed value, or None if the file cannot be read or does
+        not contain an integer.
+    """
+    v = read_str(path)
+    if v is None:
+        return None
+    try:
+        return int(v)
+    except ValueError:
+        return None
+
+
+def read_float(path: str) -> float | None:
+    """Read a sysfs file as a float.
+
+    Args:
+        path: path under /sys.
+
+    Returns:
+        The parsed value, or None if the file cannot be read or does
+        not contain a number.
+    """
+    v = read_str(path)
+    if v is None:
+        return None
+    try:
+        return float(v)
+    except ValueError:
+        return None

app/utils/systemd.py

@@ -1,6 +1,9 @@
-import asyncio
+import json
 import re
 import time
+from typing import Any
+
+from app.utils.subprocess import run_async
 
 UNIT_RE = re.compile(r"^[A-Za-z0-9@:_.\-+]+\.(service|socket|timer|target|path|slice)$")
 ACTIONS = ("start", "stop", "restart", "enable", "disable")
@@ -15,25 +18,6 @@ _DETAIL_PROPS = (
 )
 
 
-async def _run(cmd: list[str]) -> tuple[int, str, str]:
-    """Run a command, capturing stdout and stderr.
-
-    Args:
-        cmd: program and arguments.
-
-    Returns:
-        (returncode, stdout, stderr), all decoded; a missing returncode
-        (should not happen) is reported as 0.
-    """
-    proc = await asyncio.create_subprocess_exec(
-        *cmd,
-        stdout=asyncio.subprocess.PIPE,
-        stderr=asyncio.subprocess.PIPE,
-    )
-    out, err = await proc.communicate()
-    return proc.returncode or 0, out.decode(errors="replace"), err.decode(errors="replace")
-
-
 async def _systemctl(*args: str, privileged: bool = False) -> str:
     """Run a systemctl command and return its stdout.
 
@@ -47,11 +31,12 @@ async def _systemctl(*args: str, privileged: bool = False) -> str:
         The decoded stdout.
 
     Raises:
-        RuntimeError: if systemctl exits non-zero; the message is its
+        RuntimeError: if systemctl exits non-zero (or cannot be spawned);
-            stderr (or "systemctl <args> failed" when stderr is empty).
+            the message is its stderr (or "systemctl <args> failed" when
+            stderr is empty).
     """
     cmd = (["sudo", "systemctl", *args] if privileged else ["systemctl", *args])
-    rc, out, err = await _run(cmd)
+    rc, out, err = await run_async(cmd)
     if rc == 0:
         return out
     raise RuntimeError(err.strip() or f"systemctl {' '.join(args)} failed")
@@ -60,9 +45,9 @@ async def _systemctl(*args: str, privileged: bool = False) -> str:
 async def _enabled_map(force: bool = False) -> dict[str, str]:
     """Map unit name to enabled-state (enabled, disabled, static, ...).
 
-    The result of `systemctl list-unit-files --type=service` is cached
+    The result of `systemctl list-unit-files --type=service --output=json`
-    module-wide for 30 s so fast polls don't re-run it; unit_action()
+    is cached module-wide for 30 s so fast polls don't re-run it;
-    invalidates the cache after enable/disable.
+    unit_action() invalidates the cache after enable/disable.
 
     Args:
         force: bypass the cache and re-query.
@@ -75,13 +60,9 @@ async def _enabled_map(force: bool = False) -> dict[str, str]:
     now = time.monotonic()
     if not force and _enabled_cache is not None and now - _enabled_cache_at < _ENABLED_TTL:
         return _enabled_cache
-    files = await _systemctl("list-unit-files", "--type=service", "--no-legend", "--plain")
+    out = await _systemctl("list-unit-files", "--type=service", "--output=json")
-    m: dict[str, str] = {}
+    rows: list[dict[str, Any]] = json.loads(out)
-    for line in files.splitlines():
+    m: dict[str, str] = {e["unit_file"]: e["state"] for e in rows}
-        parts = line.split(None, 2)
-        if len(parts) < 2:
-            continue
-        m[parts[0]] = parts[1].strip()
     _enabled_cache = m
     _enabled_cache_at = now
     return m
@@ -90,32 +71,25 @@ async def _enabled_map(force: bool = False) -> dict[str, str]:
 async def unit_list() -> list[dict[str, str]]:
     """List all service units with their runtime and enabled state.
 
-    Merges `systemctl list-units --all` (currently known units) with the
+    Merges `systemctl list-units --all --output=json` (currently known
-    enabled-state map, so units that are configured but not active still
+    units) with the enabled-state map, so units that are configured but
-    appear (with placeholder load/active/sub values).
+    not active still appear (with placeholder load/active/sub values).
 
     Returns:
         One row per unit (name, load, active, sub, desc, enabled),
         sorted by unit name.
     """
-    out = await _systemctl(
+    out = await _systemctl("list-units", "--type=service", "--all", "--output=json")
-        "list-units", "--type=service", "--all", "--no-legend", "--plain"
-    )
     enabled = await _enabled_map()
     units: dict[str, dict[str, str]] = {}
-    for line in out.splitlines():
+    for e in json.loads(out):
-        parts = line.split(None, 4)
+        units[e["unit"]] = {
-        if len(parts) < 4:
+            "name": e["unit"],
-            continue
+            "load": e["load"],
-        name, load, active, sub = parts[0], parts[1], parts[2], parts[3]
+            "active": e["active"],
-        desc = parts[4] if len(parts) > 4 else ""
+            "sub": e["sub"],
-        units[name] = {
+            "desc": e.get("description", ""),
-            "name": name,
+            "enabled": enabled.get(e["unit"], ""),
-            "load": load,
-            "active": active,
-            "sub": sub,
-            "desc": desc,
-            "enabled": enabled.get(name, ""),
         }
     for name, state in enabled.items():
         if name not in units:

app/utils/window.py

@@ -0,0 +1,48 @@
+import math
+from dataclasses import fields
+
+from app.sample import Sample
+
+RowAgg = dict[str, float | int | None]
+
+
+def window(snap: list[Sample], max_points: int) -> list[tuple[float, dict[str, RowAgg]]]:
+    """Window-average a sample list down to at most `max_points` points.
+
+    The samples are split into consecutive chunks of ceil(n / max_points)
+    and each numeric Sample field is reduced to {avg, min, max} per chunk;
+    whole-number fields (byte counts) stay ints, fractional fields are
+    rounded to 0.1. Each point is stamped with the timestamp of the last
+    sample in its chunk.
+
+    Args:
+        snap: samples oldest first (HistoryStore.snapshot).
+        max_points: maximum number of points to emit.
+
+    Returns:
+        (timestamp, field aggregations) pairs, oldest first.
+    """
+    n = len(snap)
+    w = max(1, math.ceil(n / max_points))
+    out: list[tuple[float, dict[str, RowAgg]]] = []
+    for start in range(0, n, w):
+        chunk = snap[start : start + w]
+        vals: dict[str, list[int | float]] = {}
+        for sample in chunk:
+            for f in fields(sample):
+                if f.name == "ts":
+                    continue
+                v = getattr(sample, f.name)
+                if isinstance(v, (int, float)) and not isinstance(v, bool):
+                    vals.setdefault(f.name, []).append(v)
+        row: dict[str, RowAgg] = {}
+        for k, lst in vals.items():
+            ints = all(isinstance(v, int) for v in lst)
+            avg = sum(lst) / len(lst)
+            row[k] = {
+                "avg": round(avg) if ints else round(avg, 1),
+                "min": min(lst) if ints else round(min(lst), 1),
+                "max": max(lst) if ints else round(max(lst), 1),
+            }
+        out.append((chunk[-1].ts, row))
+    return out