Implement sleep inhibitor plugin

AGENTS.md

@@ -52,8 +52,11 @@ agent's own shell command line and kills the session.
   template-only edits. Python changes require a restart.
 - `app/systemd/units.py` — systemd unit listing/detail/actions;
   `app/journal.py` — `journalctl -o export` parser with cursors.
-- `app/plugins/` — `base.Plugin` + llamacpp plugin (talks to a router-mode
+- `app/plugins/` — `base.Plugin` (optional `open`/`close` lifecycle hooks run
-  `llama-server` on port 8080).
+  from app lifespan) + llamacpp plugin (talks to a router-mode `llama-server`
+  on port 8080) + sleep plugin (lists block-mode `systemd-inhibit` locks;
+  holds its own sleep lock via a `systemd-inhibit ... sleep infinity` child
+  while the UI switch is on, reaps stale locks by `who` marker on startup).
 
 ## Conventions
 

README.md

@@ -81,7 +81,10 @@ in the project root is read automatically (see `.env.example`).
   name for details (main PID, start time, restarts, recent journal lines) and
   run `start` / `stop` / `restart` / `enable` / `disable` actions.
 - **Plugins** — currently **llama.cpp**: model status, load/unload buttons and
-  a rescan for a `llama-server` running in router mode.
+  a rescan for a `llama-server` running in router mode; and **sleep
+  inhibitors**: active block-mode `systemd-inhibit` locks with a verdict on
+  whether the machine may sleep right now, plus a switch that makes the
+  dashboard itself hold a sleep lock (released again on shutdown).
 
 ### llama.cpp router mode
 
@@ -127,7 +130,7 @@ app/
   journal.py          # journalctl -o export parser + cursors
   render.py           # jinja env + filters
   routers/            # overview / disks / processes / journal / services / plugins
-  plugins/            # base.Plugin + llamacpp plugin
+  plugins/            # base.Plugin + llamacpp + sleep plugins
 templates/            # htmx fragments
 static/               # css, js, vendored htmx + chart.js
 deploy/               # dashboard.service

app/main.py

@@ -7,7 +7,7 @@ from fastapi.responses import HTMLResponse
 from fastapi.staticfiles import StaticFiles
 
 from app.config import get_settings
-from app.plugins import ROUTERS as PLUGIN_ROUTERS
+from app.plugins import PLUGINS, ROUTERS as PLUGIN_ROUTERS
 from app.render import BASE, render
 from app.routers import disks, overview, plugins, processes, services
 from app.routers import journal as journal_router
@@ -20,6 +20,11 @@ async def lifespan(app: FastAPI):
     settings = get_settings()
     app.state.settings = settings
     app.state.store = HistoryStore(maxlen=settings.history_maxlen)
+    for p in PLUGINS:
+        try:
+            await p.open()
+        except Exception: # noqa
+            pass
     task = asyncio.create_task(sampler_loop(app.state.store, settings.sample_interval))
     yield
     _ = task.cancel()
@@ -27,6 +32,11 @@ async def lifespan(app: FastAPI):
         await task
     except asyncio.CancelledError:
         pass
+    for p in PLUGINS:
+        try:
+            await p.close()
+        except Exception: # noqa
+            pass
 
 
 def create_app() -> FastAPI:

app/plugins/__init__.py

@@ -1,7 +1,8 @@
 from app.plugins.base import Plugin
 from app.plugins.llamacpp import plugin as llamacpp_plugin, router as llamacpp_router
+from app.plugins.sleep import plugin as sleep_plugin, router as sleep_router
 
-PLUGINS: list[Plugin] = [llamacpp_plugin]
+PLUGINS: list[Plugin] = [llamacpp_plugin, sleep_plugin]
-ROUTERS = [llamacpp_router]
+ROUTERS = [llamacpp_router, sleep_router]
 
 __all__ = ["PLUGINS", "ROUTERS", "Plugin"]

app/plugins/base.py

@@ -8,8 +8,18 @@ class Plugin:
     title: str
     description: str = ""
     skeleton_fn: Callable[[], Awaitable[str]] | None = field(default=None)
+    open_fn: Callable[[], Awaitable[None]] | None = field(default=None)
+    close_fn: Callable[[], Awaitable[None]] | None = field(default=None)
 
     async def skeleton(self) -> str:
         if self.skeleton_fn is None:
             raise NotImplementedError
         return await self.skeleton_fn()
+
+    async def open(self) -> None:
+        if self.open_fn is not None:
+            await self.open_fn()
+
+    async def close(self) -> None:
+        if self.close_fn is not None:
+            await self.close_fn()

app/plugins/llamacpp.py

@@ -156,6 +156,6 @@ async def rescan():
 plugin = Plugin(
     id="llamacpp",
     title="llama.cpp",
-    description="Loaded model status for a llama-server in router mode, with load / unload controls.",
+    description="Loaded model status for a llama-server in router mode.",
     skeleton_fn=_skeleton,
 )

app/plugins/sleep.py

@@ -0,0 +1,196 @@
+import asyncio
+import json
+import os
+import signal
+from typing import Any
+
+from fastapi import APIRouter, Form
+from fastapi.responses import HTMLResponse
+
+from app.plugins.base import Plugin
+from app.render import render
+
+router = APIRouter(prefix="/api/plugins/sleep", tags=["plugins"])
+
+WHO = "Dashboard (sleep-inhibit)"
+WHY = "dashboard: keep system awake"
+BLOCK_MODES = ("block", "block-weak")
+
+_holder: asyncio.subprocess.Process | None = None
+_toggle_lock = asyncio.Lock()
+
+
+async def _list() -> tuple[list[dict[str, Any]], str]:
+    try:
+        proc = await asyncio.create_subprocess_exec(
+            "systemd-inhibit", "--json=short", "--list",
+            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 data if isinstance(e, dict)]
+    return items, ""
+
+
+def _verdict(inhibitors: list[dict[str, Any]]) -> str:
+    for e in inhibitors:
+        whats = str(e.get("what", "")).split(":")
+        if "sleep" in whats and e.get("mode") in BLOCK_MODES:
+            return "blocked"
+    return "ok"
+
+
+def _rows(inhibitors: list[dict[str, Any]]) -> list[dict[str, str | bool]]:
+    rows: list[dict[str, str | bool]] = []
+    for e in inhibitors:
+        mode = str(e.get("mode", ""))
+        if mode not in BLOCK_MODES:
+            continue
+        user = str(e.get("user", ""))
+        pid = e.get("pid")
+        if isinstance(pid, int) and pid > 0:
+            proc = f"{user} · {pid}" if user else str(pid)
+        else:
+            proc = user
+        rows.append({
+            "who": str(e.get("who", "?")),
+            "proc": proc,
+            "what": str(e.get("what", "")),
+            "why": str(e.get("why", "")),
+            "mode": mode,
+            "own": e.get("who") == WHO,
+        })
+    return rows
+
+
+def _reap_dead_holder() -> None:
+    global _holder
+    if _holder is not None and _holder.returncode is not None:
+        _holder = None
+
+
+def _context(inhibitors: list[dict[str, Any]], error: str, message: str = "") -> dict[str, Any]:
+    _reap_dead_holder()
+    return {
+        "inhibitors": _rows(inhibitors),
+        "verdict": _verdict(inhibitors),
+        "message": message,
+        "error": error,
+        "holding": _holder is not None,
+    }
+
+
+async def _state(message: str = "", error: str = "") -> str:
+    inhibitors, err = await _list()
+    if error:
+        err = error
+    return render("plugins/sleep_state.html", **_context(inhibitors, err, message))
+
+
+async def _skeleton(message: str = "", error: str = "") -> str:
+    inhibitors, err = await _list()
+    if error:
+        err = error
+    return render("plugins/sleep_skeleton.html", **_context(inhibitors, err, message))
+
+
+async def _acquire() -> str:
+    global _holder
+    try:
+        _holder = await asyncio.create_subprocess_exec(
+            "systemd-inhibit",
+            "--what=sleep",
+            "--mode=block",
+            f"--who={WHO}",
+            f"--why={WHY}",
+            "sleep", "infinity",
+            stdout=asyncio.subprocess.DEVNULL,
+            stderr=asyncio.subprocess.DEVNULL,
+            start_new_session=True,
+        )
+    except OSError as e:
+        return str(e)[:200]
+    return ""
+
+
+async def _release() -> None:
+    global _holder
+    p, _holder = _holder, None
+    if p is None:
+        return
+    try:
+        os.killpg(p.pid, signal.SIGTERM)
+    except (ProcessLookupError, PermissionError):
+        pass
+    try:
+        _ = await asyncio.wait_for(p.wait(), 3)
+    except TimeoutError:
+        try:
+            os.killpg(p.pid, signal.SIGKILL)
+        except (ProcessLookupError, PermissionError):
+            pass
+        _ = await p.wait()
+
+
+@router.get("/state")
+async def state():
+    return HTMLResponse(await _state())
+
+
+@router.post("/toggle")
+async def toggle(on: str | None = Form(None)):
+    async with _toggle_lock:
+        if on and _holder is None:
+            err = await _acquire()
+            if err:
+                return HTMLResponse(await _skeleton(error=err))
+            return HTMLResponse(await _skeleton(message="inhibiting sleep"))
+        if not on and _holder is not None:
+            await _release()
+            return HTMLResponse(await _skeleton(message="sleep inhibition released"))
+    return HTMLResponse(await _skeleton())
+
+
+async def _open() -> None:
+    inhibitors, _err = await _list()
+    for e in inhibitors:
+        if e.get("who") != WHO:
+            continue
+        pid = e.get("pid")
+        if not isinstance(pid, int) or pid <= 0:
+            continue
+        try:
+            _ = os.kill(pid, signal.SIGTERM)
+        except ProcessLookupError:
+            pass
+
+
+async def _close() -> None:
+    await _release()
+
+
+plugin = Plugin(
+    id="sleep",
+    title="Sleep inhibitors",
+    description="Active block-mode systemd inhibitor locks.",
+    skeleton_fn=_skeleton,
+    open_fn=_open,
+    close_fn=_close,
+)

static/css/style.css

@@ -239,6 +239,7 @@ button:hover { border-color: var(--accent); }
 .badge-unloaded { color: var(--muted); }
 .badge-sleeping { color: #b3e5fc; border-color: rgba(79, 195, 247, .5); background: rgba(79, 195, 247, .1); }
 .badge-failed { color: #ffcdd2; border-color: rgba(239, 83, 80, .6); background: rgba(239, 83, 80, .12); }
+.badge-block { color: #ffcdd2; border-color: rgba(239, 83, 80, .6); background: rgba(239, 83, 80, .12); }
 .badge-downloading { color: #b3e5fc; border-color: rgba(79, 195, 247, .5); background: rgba(79, 195, 247, .1); }
 .llama-id { overflow: hidden; text-overflow: ellipsis; }
 .llama-health {
@@ -270,3 +271,4 @@ button:hover { border-color: var(--accent); }
 .llama-load select { max-width: 420px; }
 .part-mounts { max-width: 420px; overflow: hidden; text-overflow: ellipsis; }
 .part-usage { margin-left: auto; }
+.inh-own { background: rgba(79, 195, 247, .08); }

templates/plugins.html

@@ -1,5 +1,4 @@
 <div id="plugins" class="panel">
-  <div class="muted small">plugins load from <span class="mono">app/plugins/</span> &mdash; each module exposes a <span class="mono">Plugin</span> instance</div>
   {% for item in items %}
   <div class="plugin-card">
     <h3>{{ item.p.title }}</h3>

templates/plugins/sleep_skeleton.html

@@ -0,0 +1,5 @@
+<div class="sleep">
+  <div id="sleep-state" hx-get="/api/plugins/sleep/state" hx-trigger="every 5s" hx-swap="innerHTML">
+    {% include "plugins/sleep_state.html" %}
+  </div>
+</div>

templates/plugins/sleep_state.html

@@ -0,0 +1,30 @@
+{% if error %}<div class="alert">systemd-inhibit failed: {{ error }}</div>{% endif %}
+{% if message %}<div class="notice">{{ message }}</div>{% endif %}
+<div class="llama-health">
+  <span class="dot {{ "dot-failed" if verdict == "blocked" else "dot-run" }}"></span>
+  <span class="llama-health-text">{{ "sleep blocked" if verdict == "blocked" else "sleep allowed" }}</span>
+  <span class="muted small">block-mode locks only — delay-mode locks are ignored</span>
+</div>
+<label class="chk">
+  <input type="checkbox" name="on" value="1" {% if holding %}checked{% endif %} hx-post="/api/plugins/sleep/toggle" hx-target="closest .plugin-body" hx-swap="innerHTML">
+  keep system awake (this dashboard holds a sleep lock)
+</label>
+{% if inhibitors %}
+<div class="table-wrap">
+<table class="table">
+  <thead><tr><th>who</th><th>what</th><th>why</th><th>mode</th></tr></thead>
+  <tbody>
+    {% for e in inhibitors %}
+    <tr class="{{ "inh-own" if e.own else "" }}">
+      <td class="cell-clip">{{ e.who }}{% if e.proc %} <span class="muted small mono">{{ e.proc }}</span>{% endif %}</td>
+      <td>{% for w in e.what.split(":") if w %}<span class="badge">{{ w }}</span> {% endfor %}</td>
+      <td class="cell-clip muted">{{ e.why }}</td>
+      <td><span class="badge {{ "badge-block" if e.mode == "block" else "" }}">{{ e.mode }}</span></td>
+    </tr>
+    {% endfor %}
+  </tbody>
+</table>
+</div>
+{% else %}
+<div class="muted small">no active block-mode inhibitors — the system may sleep</div>
+{% endif %}