v0.8.0 - Deep health probes + auto-restart on CUDA wedge

deep_health.py:
- Synthetic probes per service, all payloads generated in-memory (BytesIO), never written to disk:
  - Parakeet: 1s of digital silence via in-memory WAV → POST /v1/audio/transcriptions
  - Magpie:   short 'hi' text → POST /v1/audio/synthesize (multipart form-data, real TTS API endpoint discovered via openapi.json)
  - vLLM:     1-token completion against currently-loaded model
- Background loop runs every 5 minutes (configurable). Best-effort: exceptions in the loop never kill it.
- Auto-restart on wedge-pattern errors (cudaErrorUnknown / CUFFT_INTERNAL_ERROR / 500 / Engine core init failed): docker restart of the affected container.
  - Rate-limited: max 3 restarts per service per 30 min.
  - Cooldown: 120 s between consecutive restarts on the same service.
  - 60 s startup grace before any auto-restart can fire after the app boots.
- Probe failures + recoveries logged via record_report(source='deep-health') into the connectivity history alongside the polling-based transitions.

API:
- GET /api/deep-health: per-service last result + auto-restart counters
- POST /api/deep-health/{service}/run: manual trigger now

UI:
- Service cards show 'Deep check ok/FAILED <time> <latency>' inline, plus a ↻ button to run-now
- Auto-restart count in 30-min window surfaced on the card when > 0
- Inline error excerpt shown for failed probes

Bug fix: server.py app startup hook was placed before the FastAPI app object was constructed (would crash on import). Moved after.

image/app/deep_health.py

@@ -0,0 +1,341 @@
+"""Deep health probes for each service.
+
+Why this exists: Triton's /health endpoint returns 200 as long as the HTTP
+layer is alive and the model is registered. It does NOT verify that the CUDA
+context inside the worker process is healthy. We've observed Parakeet getting
+its CUDA context wedged after an OOM, where /health stays green but every
+real transcription returns 500 cudaErrorUnknown.
+
+So this module sends *real* but tiny synthetic inference requests:
+  - Parakeet: 1 second of digital silence (16 kHz mono PCM, in-memory WAV)
+  - Magpie:   short text-to-speech, response audio discarded
+  - vLLM:     1-token chat completion against whatever model is loaded
+
+All synthetic payloads are generated on demand into BytesIO, sent over HTTP,
+and never touched the filesystem (on either spark-control's side or the
+target service's side beyond normal Triton/Riva working memory).
+
+When a probe fails with a signal that looks like a CUDA wedge, we
+automatically issue `docker restart <container>`. Rate-limited to 3 restarts
+per service per 30 minutes to avoid restart loops.
+"""
+from __future__ import annotations
+import asyncio
+import io
+import time
+import wave
+from dataclasses import dataclass, field
+from datetime import datetime, timezone
+from typing import Optional
+
+import httpx
+
+from .config import Settings
+from .connectivity import record_report
+from .services import ServiceDef, run_action, services_from_settings
+
+
+# Default 5-minute interval, controllable via env. Sub-minute is silly for a
+# heavy synthetic probe; we just want to catch wedges within a reasonable
+# window — much faster than the user noticing on their next real call.
+DEFAULT_INTERVAL_SEC = 300.0
+PROBE_TIMEOUT_SEC = 20.0
+RESTART_RATE_LIMIT = 3            # max auto-restarts per service
+RESTART_RATE_WINDOW_SEC = 1800.0  # within a 30-min window
+RESTART_COOLDOWN_SEC = 120.0      # don't restart again within this many seconds of the last one
+STARTUP_GRACE_SEC = 60.0          # don't auto-restart for the first minute after this app boots
+
+
+def _silence_wav(seconds: float = 1.0, sample_rate: int = 16000) -> io.BytesIO:
+    """Return an in-memory WAV file containing `seconds` of digital silence."""
+    n_frames = int(seconds * sample_rate)
+    buf = io.BytesIO()
+    with wave.open(buf, "wb") as w:
+        w.setnchannels(1)
+        w.setsampwidth(2)           # int16
+        w.setframerate(sample_rate)
+        w.writeframes(b"\x00\x00" * n_frames)
+    buf.seek(0)
+    return buf
+
+
+def _looks_like_wedge(error: str) -> bool:
+    """Heuristic: does this error string look like a stuck CUDA context that
+    a container restart would clear? We want to be conservative — only act
+    on signals we're confident about, otherwise leave the user in charge."""
+    err = (error or "").lower()
+    needles = [
+        "cudaerrorunknown",
+        "cuda error: unknown",
+        "cuda kernel errors",
+        "internal server error",
+        "engine core initialization failed",
+        "503",   # service unavailable from a dependency
+        "500",   # generic 5xx with a body that may not parse
+    ]
+    return any(n in err for n in needles)
+
+
+@dataclass
+class ProbeResult:
+    ok: bool
+    at: str
+    latency_ms: Optional[int] = None
+    error: str = ""
+    note: str = ""
+
+
+@dataclass
+class ServiceState:
+    last: Optional[ProbeResult] = None
+    last_ok_at: Optional[str] = None
+    restarts: list[float] = field(default_factory=list)
+
+
+class DeepHealth:
+    def __init__(self, settings: Settings, interval_sec: float = DEFAULT_INTERVAL_SEC) -> None:
+        self.settings = settings
+        self.interval_sec = interval_sec
+        self.state: dict[str, ServiceState] = {
+            "parakeet": ServiceState(),
+            "magpie": ServiceState(),
+            "vllm": ServiceState(),
+        }
+        self._stop = asyncio.Event()
+        self._boot_at = time.monotonic()
+
+    # ---- probes ---------------------------------------------------------
+
+    async def probe_parakeet(self) -> ProbeResult:
+        s = self.settings
+        now_iso = datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")
+        if not s.parakeet_host:
+            return ProbeResult(ok=False, at=now_iso, error="not configured")
+        url = f"http://{s.parakeet_host}:{s.parakeet_port}/v1/audio/transcriptions"
+        wav = _silence_wav(1.0)
+        t0 = time.monotonic()
+        try:
+            async with httpx.AsyncClient(timeout=PROBE_TIMEOUT_SEC) as c:
+                r = await c.post(
+                    url,
+                    files={"file": ("probe.wav", wav, "audio/wav")},
+                    data={"model": "parakeet-tdt-0.6b-v3"},
+                )
+            latency = round((time.monotonic() - t0) * 1000)
+            if 200 <= r.status_code < 300:
+                return ProbeResult(ok=True, at=now_iso, latency_ms=latency)
+            return ProbeResult(
+                ok=False,
+                at=now_iso,
+                latency_ms=latency,
+                error=f"HTTP {r.status_code}: {r.text[:240]}",
+            )
+        except Exception as e:
+            return ProbeResult(ok=False, at=now_iso, error=f"{type(e).__name__}: {e}")
+
+    async def probe_magpie(self) -> ProbeResult:
+        s = self.settings
+        now_iso = datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")
+        if not s.magpie_host:
+            return ProbeResult(ok=False, at=now_iso, error="not configured")
+        # Magpie /v1/audio/synthesize expects multipart form-data, not JSON.
+        # The (None, value) tuple in httpx's `files=` produces a non-file form field.
+        url = f"http://{s.magpie_host}:{s.magpie_port}/v1/audio/synthesize"
+        form: dict = {"text": (None, "hi"), "language": (None, "en-US")}
+        t0 = time.monotonic()
+        try:
+            async with httpx.AsyncClient(timeout=PROBE_TIMEOUT_SEC) as c:
+                r = await c.post(url, files=form)
+            latency = round((time.monotonic() - t0) * 1000)
+            if 200 <= r.status_code < 300:
+                return ProbeResult(ok=True, at=now_iso, latency_ms=latency)
+            # 4xx that aren't 5xx mean server is alive but our payload is off —
+            # don't classify as wedge.
+            if 400 <= r.status_code < 500:
+                return ProbeResult(
+                    ok=True,
+                    at=now_iso,
+                    latency_ms=latency,
+                    note=f"{r.status_code} — server alive (probe payload may need a voice name)",
+                )
+            return ProbeResult(
+                ok=False,
+                at=now_iso,
+                latency_ms=latency,
+                error=f"HTTP {r.status_code}: {r.text[:240]}",
+            )
+        except Exception as e:
+            return ProbeResult(ok=False, at=now_iso, error=f"{type(e).__name__}: {e}")
+
+    async def probe_vllm(self) -> ProbeResult:
+        s = self.settings
+        now_iso = datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")
+        if not s.spark1_host:
+            return ProbeResult(ok=False, at=now_iso, error="not configured")
+        base = f"http://{s.spark1_host}:{s.vllm_port}"
+        try:
+            async with httpx.AsyncClient(timeout=5.0) as c:
+                r = await c.get(f"{base}/v1/models")
+                r.raise_for_status()
+                models = r.json().get("data") or []
+            if not models:
+                return ProbeResult(ok=False, at=now_iso, error="no model loaded")
+            model_id = models[0]["id"]
+        except Exception as e:
+            return ProbeResult(ok=False, at=now_iso, error=f"list models: {type(e).__name__}: {e}")
+        t0 = time.monotonic()
+        try:
+            async with httpx.AsyncClient(timeout=PROBE_TIMEOUT_SEC) as c:
+                r = await c.post(
+                    f"{base}/v1/chat/completions",
+                    json={
+                        "model": model_id,
+                        "messages": [{"role": "user", "content": "hi"}],
+                        "max_tokens": 1,
+                        "temperature": 0,
+                    },
+                )
+            latency = round((time.monotonic() - t0) * 1000)
+            if 200 <= r.status_code < 300:
+                return ProbeResult(ok=True, at=now_iso, latency_ms=latency)
+            return ProbeResult(
+                ok=False,
+                at=now_iso,
+                latency_ms=latency,
+                error=f"HTTP {r.status_code}: {r.text[:240]}",
+            )
+        except Exception as e:
+            return ProbeResult(ok=False, at=now_iso, error=f"{type(e).__name__}: {e}")
+
+    # ---- orchestration --------------------------------------------------
+
+    PROBES = {
+        "parakeet": "probe_parakeet",
+        "magpie": "probe_magpie",
+        "vllm": "probe_vllm",
+    }
+
+    async def run_one(self, service: str) -> ProbeResult:
+        fn = getattr(self, self.PROBES[service])
+        result: ProbeResult = await fn()
+        st = self.state[service]
+        prev_ok = st.last.ok if st.last else None
+        st.last = result
+        if result.ok:
+            st.last_ok_at = result.at
+
+        # Log to connectivity history: every failure, plus the first success
+        # after a failure (recovery), plus the first probe ever — but skip
+        # the "still ok" steady-state to keep the log readable.
+        if not result.ok:
+            record_report(
+                service,
+                ok=False,
+                source="deep-health",
+                detail=result.error[:240],
+                latency_ms=result.latency_ms,
+            )
+        elif prev_ok is False:
+            record_report(
+                service,
+                ok=True,
+                source="deep-health",
+                detail="recovered" + (f" — {result.note}" if result.note else ""),
+                latency_ms=result.latency_ms,
+            )
+        elif prev_ok is None:
+            record_report(
+                service,
+                ok=True,
+                source="deep-health",
+                detail="first probe ok" + (f" — {result.note}" if result.note else ""),
+                latency_ms=result.latency_ms,
+            )
+
+        # Maybe auto-restart
+        if not result.ok and _looks_like_wedge(result.error):
+            await self._maybe_restart(service, result.error)
+        return result
+
+    async def _maybe_restart(self, service: str, error: str) -> None:
+        # No restarts during the boot grace period.
+        if time.monotonic() - self._boot_at < STARTUP_GRACE_SEC:
+            return
+        st = self.state[service]
+        now = time.monotonic()
+        st.restarts = [t for t in st.restarts if now - t < RESTART_RATE_WINDOW_SEC]
+        if st.restarts and now - st.restarts[-1] < RESTART_COOLDOWN_SEC:
+            return  # already restarted recently, give it time
+        if len(st.restarts) >= RESTART_RATE_LIMIT:
+            record_report(
+                service,
+                ok=False,
+                source="deep-health",
+                detail=f"rate-limited; not auto-restarting (would be #{len(st.restarts)+1} in 30 min)",
+            )
+            return
+        services = services_from_settings(self.settings)
+        if service not in services:
+            return
+        svc = services[service]
+        if not svc.host or not svc.user:
+            return
+        result = await run_action(self.settings, svc, "restart")
+        st.restarts.append(now)
+        ok = result.get("ok", False)
+        record_report(
+            service,
+            ok=False,
+            source="deep-health",
+            detail=f"auto-restart triggered (wedge: {error[:120]}); restart {'OK' if ok else 'FAILED'}",
+        )
+
+    async def run_all(self) -> dict[str, ProbeResult]:
+        results = {}
+        for name in self.PROBES:
+            results[name] = await self.run_one(name)
+        return results
+
+    async def run_periodic(self) -> None:
+        """Long-running loop. Cancel via .stop()."""
+        # Brief initial wait to let app finish startup
+        try:
+            await asyncio.wait_for(self._stop.wait(), timeout=10.0)
+            return
+        except asyncio.TimeoutError:
+            pass
+        while not self._stop.is_set():
+            try:
+                await self.run_all()
+            except Exception:
+                # Never let the loop die; the periodic check is best-effort
+                pass
+            try:
+                await asyncio.wait_for(self._stop.wait(), timeout=self.interval_sec)
+                return
+            except asyncio.TimeoutError:
+                continue
+
+    def stop(self) -> None:
+        self._stop.set()
+
+    def summary(self) -> dict:
+        out = {}
+        for name, st in self.state.items():
+            last = st.last
+            out[name] = {
+                "last_ok_at": st.last_ok_at,
+                "last": (
+                    {
+                        "ok": last.ok,
+                        "at": last.at,
+                        "latency_ms": last.latency_ms,
+                        "error": last.error,
+                        "note": last.note,
+                    }
+                    if last
+                    else None
+                ),
+                "auto_restarts_window": len(st.restarts),
+            }
+        return out

image/app/server.py

@@ -12,6 +12,7 @@ from typing import Literal
 from .config import Settings
 from .connectivity import get_mac, record_report, record_state, summary as connectivity_summary
 from .custom_services import add_custom_service, delete_custom_service
+from .deep_health import DeepHealth
 from .download import DownloadManager
 from .hardware import HardwareProbe
 from .health import check_magpie, check_parakeet, check_vllm
@@ -22,6 +23,7 @@ from .services import docker_state, run_action, services_from_settings
 from .ssh import ssh_run
 from .swap import SwapManager
 from .updates import UpdateManager, get_update_status
+from .validate import validate_launch
 from .wol import send_local_broadcast, send_via_peer
 
 
@@ -32,9 +34,22 @@ download_manager = DownloadManager(settings)
 update_manager = UpdateManager(settings)
 hardware_probe = HardwareProbe(settings)
 nim_manager = NimManager(settings)
+deep_health = DeepHealth(settings)
 
 app = FastAPI(title="spark-control", version="0.1.0")
 
+
+@app.on_event("startup")
+async def _start_deep_health() -> None:
+    # Fire-and-forget; the loop catches its own exceptions.
+    asyncio.create_task(deep_health.run_periodic())
+
+
+@app.on_event("shutdown")
+async def _stop_deep_health() -> None:
+    deep_health.stop()
+
+
 _STATIC_DIR = Path(__file__).resolve().parent / "static"
 app.mount("/static", StaticFiles(directory=_STATIC_DIR), name="static")
 
@@ -136,6 +151,27 @@ async def get_connectivity() -> dict:
     return connectivity_summary()
 
 
+@app.get("/api/deep-health")
+async def get_deep_health() -> dict:
+    """Last result + auto-restart counters for each service's synthetic probe."""
+    return deep_health.summary()
+
+
+@app.post("/api/deep-health/{service}/run")
+async def run_deep_health(service: str) -> dict:
+    """Manually run a single service's deep-health probe right now."""
+    if service not in deep_health.PROBES:
+        raise HTTPException(404, f"unknown service: {service}")
+    result = await deep_health.run_one(service)
+    return {
+        "ok": result.ok,
+        "at": result.at,
+        "latency_ms": result.latency_ms,
+        "error": result.error,
+        "note": result.note,
+    }
+
+
 class HealthEventBody(BaseModel):
     service: str                 # e.g. "parakeet", "magpie", "vllm"
     ok: bool                     # true on success, false on failure
@@ -434,6 +470,15 @@ class SwapRequest(BaseModel):
     dry_run: bool = False
 
 
+@app.post("/api/swap/{key}/validate")
+async def validate_swap(key: str) -> dict:
+    """Pre-flight check: run vLLM's argparse layer against the proposed launch
+    command WITHOUT starting an engine. Cheap (~5 s) and doesn't disturb the
+    currently-loaded model.
+    """
+    return await validate_launch(key, catalog, settings)
+
+
 @app.post("/api/swap")
 async def post_swap(req: SwapRequest) -> dict:
     if not settings.configured and not req.dry_run:

image/app/static/app.js

@@ -17,6 +17,7 @@ const state = {
   config: {},
   configured: true,
   timer_handle: null,
+  deep_health: {},
 };
 
 const el = (sel) => document.querySelector(sel);
@@ -73,8 +74,10 @@ function renderCards() {
         <button class="btn ${isActive ? '' : 'primary'}" data-swap-key="${key}" ${isActive || isSwapping ? 'disabled' : ''}>
           ${isActive ? 'Current' : 'Switch to this'}
         </button>
+        <button class="btn test-btn" data-test-key="${key}" title="Pre-flight check the launch command without starting the engine">Test</button>
         <button class="btn adv-btn" data-adv-key="${key}" title="Advanced settings">Advanced</button>
       </div>
+      <div class="test-result hidden" data-test-result-for="${key}"></div>
     `;
     root.appendChild(card);
   }
@@ -84,6 +87,37 @@ function renderCards() {
   for (const btn of root.querySelectorAll('[data-adv-key]')) {
     btn.addEventListener('click', () => openAdvanced(btn.dataset.advKey));
   }
+  for (const btn of root.querySelectorAll('[data-test-key]')) {
+    btn.addEventListener('click', () => testLaunch(btn.dataset.testKey, btn));
+  }
+}
+
+async function testLaunch(key, btn) {
+  const resultEl = document.querySelector(`[data-test-result-for="${key}"]`);
+  if (!resultEl) return;
+  const originalText = btn.textContent;
+  btn.disabled = true;
+  btn.textContent = 'Testing…';
+  resultEl.classList.remove('hidden', 'ok', 'fail');
+  resultEl.innerHTML = '<span class="muted small">Checking launch args against vLLM\'s parser…</span>';
+  try {
+    const r = await fetchJSON(`/api/swap/${encodeURIComponent(key)}/validate`, { method: 'POST' });
+    if (r.ok) {
+      resultEl.classList.add('ok');
+      resultEl.innerHTML = `<span class="ok-mark">✓</span> Launch args parse OK. <span class="muted small">(Doesn't guarantee runtime success — only catches argparse-level issues.)</span>`;
+    } else {
+      resultEl.classList.add('fail');
+      const err = escapeHtml(r.error || 'unknown error');
+      const stage = r.stage ? ` <span class="muted small">(${escapeHtml(r.stage)})</span>` : '';
+      resultEl.innerHTML = `<span class="fail-mark">✗</span> Would fail: ${err}${stage}`;
+    }
+  } catch (e) {
+    resultEl.classList.add('fail');
+    resultEl.innerHTML = `<span class="fail-mark">✗</span> Test failed: ${escapeHtml(e.message)}`;
+  } finally {
+    btn.disabled = false;
+    btn.textContent = originalText;
+  }
 }
 
 function renderCurrent(status) {
@@ -380,6 +414,35 @@ async function renderServices() {
     const restartsRow = s.restart_count != null && s.restart_count > 1
       ? `<div class="row"><span class="k">Restarts</span><span class="v">${s.restart_count}</span></div>`
       : '';
+    const dh = state.deep_health?.[name];
+    let deepRow = '';
+    if (dh && dh.last) {
+      const last = dh.last;
+      const when = (last.at || '').slice(11, 19);  // HH:MM:SS
+      const verdict = last.ok
+        ? `<span class="dh-ok">deep check ok</span>`
+        : `<span class="dh-fail">deep check FAILED</span>`;
+      const lat = last.latency_ms != null ? ` <span class="muted">${last.latency_ms} ms</span>` : '';
+      const restarts = dh.auto_restarts_window > 0
+        ? ` <span class="muted">· ${dh.auto_restarts_window} auto-restart${dh.auto_restarts_window === 1 ? '' : 's'} in 30 min</span>`
+        : '';
+      deepRow = `
+        <div class="row deep-row">
+          <span class="k">Deep</span>
+          <span class="v deep-v">${verdict} <span class="muted small">${escapeHtml(when)}</span>${lat}${restarts}</span>
+          <button class="icon-btn dh-run-btn" data-dh-run="${escapeHtml(name)}" title="Run deep check now">↻</button>
+        </div>
+        ${last.ok ? '' : `<div class="deep-error muted small">${escapeHtml((last.error || last.note || '').slice(0, 200))}</div>`}
+      `;
+    } else if (dh) {
+      deepRow = `
+        <div class="row deep-row">
+          <span class="k">Deep</span>
+          <span class="v muted-v">no probe yet</span>
+          <button class="icon-btn dh-run-btn" data-dh-run="${escapeHtml(name)}" title="Run deep check now">↻</button>
+        </div>
+      `;
+    }
     card.innerHTML = `
       <div class="head">
         <span class="name">${escapeHtml(name)}</span>
@@ -390,6 +453,7 @@ async function renderServices() {
       ${urlRow}
       ${modelRow}
       ${restartsRow}
+      ${deepRow}
       <div class="service-actions">
         <button class="btn" data-svc-action="${name}:start" ${disable('start') ? 'disabled' : ''}>Start</button>
         <button class="btn" data-svc-action="${name}:restart" ${disable('restart') ? 'disabled' : ''}>Restart</button>
@@ -401,6 +465,25 @@ async function renderServices() {
   for (const btn of grid.querySelectorAll('.btn[data-svc-action]')) {
     btn.addEventListener('click', () => onServiceAction(btn.dataset.svcAction));
   }
+  for (const btn of grid.querySelectorAll('[data-dh-run]')) {
+    btn.addEventListener('click', () => onDeepHealthRun(btn.dataset.dhRun, btn));
+  }
+}
+
+async function onDeepHealthRun(name, btn) {
+  btn.disabled = true;
+  const orig = btn.textContent;
+  btn.textContent = '…';
+  try {
+    await fetchJSON(`/api/deep-health/${encodeURIComponent(name)}/run`, { method: 'POST' });
+  } catch (e) {
+    console.warn('deep-health run failed', e);
+  } finally {
+    try { state.deep_health = await fetchJSON('/api/deep-health'); } catch {}
+    btn.textContent = orig;
+    btn.disabled = false;
+    renderServices();
+  }
 }
 
 async function onServiceAction(key) {
@@ -635,6 +718,7 @@ async function pollStatus() {
     // Refresh services state lazily — every 5s poll triggers this too.
     try {
       state.services = await fetchJSON('/api/services');
+      try { state.deep_health = await fetchJSON('/api/deep-health'); } catch {}
       renderServices();
     } catch {}
     if (status.current_swap_job && status.current_swap_job !== state.swap_job_id) {

image/app/static/style.css

@@ -622,6 +622,19 @@ main {
 .service-card .row .v.copyable.copied { outline: 1px solid var(--accent); background: rgba(74, 222, 128, 0.05); }
 .service-card .row .icon-btn { padding: 3px 6px; }
 .service-card .row .icon-btn svg { width: 12px; height: 12px; }
+.service-card .deep-row .deep-v { display: flex; align-items: center; gap: 6px; font-family: inherit; flex-wrap: wrap; }
+.service-card .dh-ok { color: var(--accent); }
+.service-card .dh-fail { color: var(--error); font-weight: 500; }
+.service-card .dh-run-btn { font-family: inherit; }
+.service-card .deep-error {
+  padding: 4px 8px;
+  background: rgba(239, 68, 68, 0.06);
+  border-left: 2px solid var(--error);
+  border-radius: 4px;
+  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
+  font-size: 11px;
+  word-break: break-word;
+}
 
 .service-actions {
   display: flex;
@@ -701,9 +714,24 @@ main {
 .card.active .btn { background: rgba(74, 222, 128, 0.12); color: var(--accent); border-color: rgba(74, 222, 128, 0.4); }
 .card-actions { display: flex; gap: 6px; }
 .card-actions .btn.primary { flex: 1; }
-.card .adv-btn { padding: 8px 12px; font-size: 12px; }
+.card .adv-btn,
+.card .test-btn { padding: 8px 12px; font-size: 12px; }
 .card .custom-pill { color: var(--info); border-color: rgba(96, 165, 250, 0.4); }
 
+.test-result {
+  font-size: 12px;
+  line-height: 1.45;
+  padding: 8px 10px;
+  border-radius: 5px;
+  margin-top: 4px;
+  border: 1px solid var(--border);
+  background: var(--surface-2);
+}
+.test-result.ok { border-color: rgba(74, 222, 128, 0.4); background: rgba(74, 222, 128, 0.04); }
+.test-result.fail { border-color: rgba(239, 68, 68, 0.45); background: rgba(239, 68, 68, 0.06); word-break: break-word; }
+.test-result .ok-mark { color: var(--accent); font-weight: 600; }
+.test-result .fail-mark { color: var(--error); font-weight: 600; }
+
 .footer {
   margin-top: 28px;
   padding-top: 16px;

image/app/validate.py

@@ -0,0 +1,137 @@
+"""Pre-flight validation of a proposed vLLM launch command.
+
+Runs vLLM's own argparse layer (EngineArgs) inside the vllm_node container WITHOUT
+starting the engine. Catches:
+
+  * unknown flag names (typos)
+  * bad types / values that argparse rejects
+  * deprecated flags removed in the installed vLLM version
+
+Does NOT catch (these surface only during real engine init):
+  * model-architecture-specific constraints (e.g. Qwen3.6 Mamba block_size)
+  * OOM at weight-loading time
+  * Triton / CUDA-kernel compatibility errors
+
+A pre-flight check that returns "ok" is therefore NOT a guarantee — but a
+"failed" verdict is a definitive 'don't bother with the real swap'.
+"""
+from __future__ import annotations
+import json
+import shlex
+from typing import Any
+
+from .config import Settings
+from .models import Catalog, build_launch_command
+from .ssh import ssh_run
+
+
+# Validates the proposed args against the same combined parser vLLM uses for
+# `vllm serve` (engine args + server args + frontend args). Returns one JSON
+# line on stdout: {"ok": true, ...} or {"ok": false, ...}.
+_VALIDATOR_SCRIPT = r"""
+import argparse, json, sys
+
+# Mirror what `vllm serve` does internally: FlexibleArgumentParser (which is
+# more lenient about dashes vs underscores) wrapped with make_arg_parser
+# (which adds engine + server + frontend args).
+parser = None
+try:
+    # Newer vLLM path
+    from vllm.utils.argparse_utils import FlexibleArgumentParser
+except Exception:
+    try:
+        # Older fallback
+        from vllm.engine.arg_utils import FlexibleArgumentParser
+    except Exception:
+        FlexibleArgumentParser = argparse.ArgumentParser  # type: ignore
+
+try:
+    from vllm.entrypoints.openai.cli_args import make_arg_parser
+    parser = make_arg_parser(FlexibleArgumentParser(add_help=False))
+except Exception:
+    pass
+if parser is None:
+    try:
+        from vllm.engine.arg_utils import EngineArgs
+        parser = FlexibleArgumentParser(add_help=False)
+        EngineArgs.add_cli_args(parser)
+    except Exception as e:
+        print(json.dumps({"ok": False, "stage": "import", "error": f"{type(e).__name__}: {e}"}))
+        sys.exit(0)
+
+class _ArgError(Exception):
+    pass
+
+def _err(message):
+    raise _ArgError(message)
+
+parser.error = _err  # capture argparse errors instead of sys.exit(2)
+
+try:
+    raw = sys.stdin.read()
+    arglist = json.loads(raw)
+    ns = parser.parse_args(arglist)
+    print(json.dumps({"ok": True, "model": getattr(ns, "model", None)}))
+except _ArgError as e:
+    print(json.dumps({"ok": False, "stage": "parse", "error": str(e)}))
+except SystemExit as e:
+    print(json.dumps({"ok": False, "stage": "parse", "error": f"argparse exit {e.code}"}))
+except Exception as e:
+    print(json.dumps({"ok": False, "stage": "parse", "error": f"{type(e).__name__}: {e}"}))
+"""
+
+
+def _vllm_arg_list(key: str, model_def, catalog: Catalog) -> list[str]:
+    """Reconstruct the args list passed to `vllm serve` (without the positional model)."""
+    cmd = build_launch_command(key, model_def, catalog.defaults)
+    # build_launch_command yields:
+    #   ./launch-cluster.sh [--solo] -d exec vllm serve <repo> <args...>
+    # We just want the bits after `vllm serve <repo>`.
+    tokens = shlex.split(cmd)
+    if "serve" not in tokens:
+        return []
+    i = tokens.index("serve")
+    after = tokens[i + 1 :]  # repo, then args
+    if not after:
+        return []
+    args = after[1:]  # drop the repo
+    # EngineArgs expects --model=REPO rather than positional, so prepend it.
+    return [f"--model={after[0]}", *args]
+
+
+async def validate_launch(key: str, catalog: Catalog, settings: Settings) -> dict:
+    if key not in catalog.models:
+        return {"ok": False, "stage": "lookup", "error": f"unknown model: {key}"}
+    if not settings.spark1_host or not settings.spark1_user:
+        return {"ok": False, "stage": "config", "error": "spark1 not configured"}
+
+    model = catalog.models[key]
+    arg_list = _vllm_arg_list(key, model, catalog)
+    if not arg_list:
+        return {"ok": False, "stage": "build", "error": "failed to build args list"}
+
+    payload = json.dumps(arg_list).replace("'", "'\\''")
+    # Pipe the JSON args list to a here-doc Python invocation. The validator
+    # reads from stdin to avoid shell-escaping the args themselves.
+    cmd = (
+        f"echo '{payload}' | docker exec -i vllm_node python3 -c "
+        + shlex.quote(_VALIDATOR_SCRIPT)
+    )
+
+    rc, out, err = await ssh_run(settings.spark1_host, settings.spark1_user, cmd, settings, timeout=20)
+    if rc != 0 and not out.strip():
+        return {
+            "ok": False,
+            "stage": "ssh",
+            "error": err.strip() or f"rc={rc}",
+            "cmd_args": arg_list,
+            "launch_cmd": build_launch_command(key, model, catalog.defaults),
+        }
+    last = out.strip().splitlines()[-1] if out.strip() else ""
+    try:
+        result: dict[str, Any] = json.loads(last)
+    except json.JSONDecodeError:
+        result = {"ok": False, "stage": "decode", "error": "validator did not return JSON", "raw": out[-500:]}
+    result["cmd_args"] = arg_list
+    result["launch_cmd"] = build_launch_command(key, model, catalog.defaults)
+    return result

image/models.yaml

@@ -66,6 +66,7 @@ models:
     vllm_args:
       - --gpu-memory-utilization=0.85
       - --max-model-len=65536
+      - --max-num-batched-tokens=16384
       - --reasoning-parser=qwen3
       - --moe_backend=flashinfer_cutlass
       - --load-format=fastsafetensors

known-issues.md

@@ -20,6 +20,10 @@ The trick is the `docker run --rm alpine chown` — it runs as root inside the t
 
 This flag is Blackwell-specific. If vLLM in the container reports `unrecognized arguments: --moe_backend` or similar, edit `models.yaml` for `qwen36` and drop that flag. The swap UI does NOT auto-fallback in v0.1 — failure surfaces in the log stream.
 
+## Qwen3.6 Mamba block-size assertion (fixed in v0.6.0:1)
+
+Qwen3.6 uses a Mamba-attention hybrid that requires `--max-num-batched-tokens >= 2096`. vLLM's default is 2048, which trips `AssertionError: In Mamba cache align mode, block_size (2096) must be <= max_num_batched_tokens (2048)`. Fix: bake `--max-num-batched-tokens=16384` into the bundled qwen36 entry — matches the upstream qwen3.5-35b-a3b-fp8 recipe.
+
 ## Two SSH paths to Spark 1 from the laptop
 
 `ssh <spark-user>@<spark-1-ip>` does NOT work from the laptop because the NVIDIA Sync ssh_config only has a Host entry for `<spark-1-host>.local`. Always use the `.local` hostname or `<spark-2-ip>`-style entries that ARE matched.

package/startos/versions/v0_1_0.ts

@@ -1,10 +1,10 @@
 import { VersionInfo, IMPOSSIBLE } from '@start9labs/start-sdk'
 
 export const v0_1_0 = VersionInfo.of({
-  version: '0.6.0:0',
+  version: '0.8.0:2',
   releaseNotes: {
     en_US:
-      'v0.6: Service-level connectivity tracking and a passive failure-report endpoint. The connectivity log now records up/down transitions for Parakeet, Magpie, and vLLM in addition to the Spark hosts (driven by the existing /api/status and /api/services polling). A new POST /api/health-event endpoint lets external apps (e.g. Open WebUI) record failures they observed even when the failure was brief enough to slip between polls. The Connectivity log dialog shows hosts and services with separate badges, and reports appear inline with their source app + error detail.',
+      'v0.8: deep health probes. Every 5 minutes, Spark Control sends a tiny synthetic inference request to each service (1 second of silent audio to Parakeet, short text to Magpie, 1-token completion to vLLM). All payloads are generated in-memory and never written to disk. If a probe returns CUDA-error / 5xx signals while the container is still "up" — i.e. the classic Triton-wedge pattern where /health stays green but real inference fails — Spark Control automatically restarts the affected container. Rate-limited to 3 auto-restarts per service per 30 minutes. Each service card now shows the last deep-check timestamp, latency, and an inline "Run now" button. Failures and recoveries are logged into the connectivity history with source=deep-health.',
   },
   migrations: {
     up: async ({ effects }) => {},