refactor(admin): focus System tab temperatures on the CPU die

The Temperatures box listed every component sysinfo exposes (per-core,
chipset, NVMe…), dominating the System tab. Surface only the CPU
die/package reading and collapse the rest behind a disclosure.

Add a tested pure helper, pickCpuTemp, that selects the best CPU sensor
(Intel package → AMD Tctl/Tdie → hottest core → any cpu/coretemp → null),
and render it via a shared Temp snippet with the remaining sensors in a
default-closed "N other sensors" details element.

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

frontend/src/lib/admin/temps.test.ts

@@ -0,0 +1,43 @@
+import { describe, it, expect } from 'vitest';
+import { pickCpuTemp } from './temps';
+import type { TempStat } from '$lib/api/admin';
+
+function t(label: string, celsius: number): TempStat {
+    return { label, celsius, max_celsius: celsius, critical_celsius: 100 };
+}
+
+describe('pickCpuTemp', () => {
+    it('returns null when there are no sensors', () => {
+        expect(pickCpuTemp([])).toBeNull();
+    });
+
+    it('prefers the Intel package sensor over individual cores', () => {
+        const temps = [
+            t('coretemp Core 0', 50),
+            t('coretemp Core 1', 49),
+            t('coretemp Package id 0', 51),
+            t('acpitz temp1', 28)
+        ];
+        expect(pickCpuTemp(temps)?.label).toBe('coretemp Package id 0');
+    });
+
+    it('falls back to the AMD Tctl/Tdie sensor when there is no package', () => {
+        const temps = [t('k10temp Tctl', 55), t('nvme Composite', 41)];
+        expect(pickCpuTemp(temps)?.label).toBe('k10temp Tctl');
+    });
+
+    it('falls back to the hottest core when only per-core sensors exist', () => {
+        const temps = [t('coretemp Core 0', 50), t('coretemp Core 3', 58), t('coretemp Core 1', 49)];
+        expect(pickCpuTemp(temps)?.label).toBe('coretemp Core 3');
+    });
+
+    it('falls back to any cpu/coretemp-labelled sensor as a last resort', () => {
+        const temps = [t('nvme Composite', 41), t('cpu_thermal', 47)];
+        expect(pickCpuTemp(temps)?.label).toBe('cpu_thermal');
+    });
+
+    it('returns null when nothing looks like a CPU sensor', () => {
+        const temps = [t('nvme Composite', 41), t('acpitz temp1', 28)];
+        expect(pickCpuTemp(temps)).toBeNull();
+    });
+});

frontend/src/lib/admin/temps.ts

@@ -0,0 +1,25 @@
+import type { TempStat } from '$lib/api/admin';
+
+/** Pick the sensor that best represents the CPU die/package temperature
+ *  from a heterogeneous component list. Intel exposes
+ *  `coretemp Package id 0`; AMD exposes `k10temp Tctl`/`Tdie`. When neither
+ *  is present we fall back to the hottest individual core, then to any
+ *  CPU-ish sensor, and finally `null` (nothing CPU-related — e.g. only NVMe
+ *  / chipset sensors are exposed). Used to keep the System tab focused on
+ *  the one reading operators care about, with the rest tucked away. */
+export function pickCpuTemp(temps: TempStat[]): TempStat | null {
+    const byLabel = (re: RegExp) => temps.find((t) => re.test(t.label)) ?? null;
+    return (
+        byLabel(/package/i) ??
+        byLabel(/tctl|tdie|k10temp/i) ??
+        hottestCore(temps) ??
+        byLabel(/cpu|coretemp/i) ??
+        null
+    );
+}
+
+function hottestCore(temps: TempStat[]): TempStat | null {
+    const cores = temps.filter((t) => /core\s*\d+/i.test(t.label));
+    if (cores.length === 0) return null;
+    return cores.reduce((a, b) => (b.celsius > a.celsius ? b : a));
+}

frontend/src/routes/admin/system/+page.svelte

@@ -8,8 +8,16 @@
         type StorageStats
     } from '$lib/api/admin';
     import { formatBytes as fmtBytes } from '$lib/upload-validation';
+    import { pickCpuTemp } from '$lib/admin/temps';
 
     let stats: SystemStats | null = $state(null);
+
+    // The component list is noisy (every core, chipset, NVMe…). Surface the
+    // CPU die/package reading and tuck the rest behind a disclosure.
+    const cpuTemp = $derived.by(() => (stats ? pickCpuTemp(stats.temperatures) : null));
+    const otherTemps = $derived.by(() =>
+        stats ? stats.temperatures.filter((t) => t !== cpuTemp) : []
+    );
     let error: string | null = $state(null);
     let timer: ReturnType<typeof setInterval> | null = null;
     let storageTimer: ReturnType<typeof setInterval> | null = null;
@@ -168,36 +176,19 @@
             <h2>Temperatures</h2>
             {#if stats.temperatures.length === 0}
                 <p class="muted">Sensor data unavailable (not exposed in this environment).</p>
+            {:else if cpuTemp}
+                {@render Temp(cpuTemp)}
+                {#if otherTemps.length > 0}
+                    <details class="more-temps">
+                        <summary>{otherTemps.length} other sensor{otherTemps.length === 1 ? '' : 's'}</summary>
+                        {#each otherTemps as t (t.label)}
+                            {@render Temp(t)}
+                        {/each}
+                    </details>
+                {/if}
             {:else}
                 {#each stats.temperatures as t (t.label)}
-                    {@const limit = t.critical_celsius ?? 100}
-                    {@const pct = Math.min(100, Math.max(0, (t.celsius / limit) * 100))}
-                    <div class="temp">
-                        <div class="temp-head">
-                            <span class="temp-label">{t.label}</span>
-                            <span class="temp-val">{t.celsius.toFixed(0)}°C</span>
-                        </div>
-                        <div
-                            class="bar"
-                            role="progressbar"
-                            aria-valuenow={t.celsius}
-                            aria-valuemin="0"
-                            aria-valuemax={limit}
-                            aria-label="{t.label} {t.celsius.toFixed(0)}°C"
-                        >
-                            <div
-                                class="fill"
-                                class:high={pct >= 90}
-                                class:mid={pct >= 70 && pct < 90}
-                                style:width="{pct}%"
-                            ></div>
-                        </div>
-                        <p class="sub">
-                            {#if t.max_celsius !== null}max {t.max_celsius.toFixed(0)}°C{/if}
-                            {#if t.critical_celsius !== null}
-                                · crit {t.critical_celsius.toFixed(0)}°C{/if}
-                        </p>
-                    </div>
+                    {@render Temp(t)}
                 {/each}
             {/if}
         </article>
@@ -299,6 +290,37 @@
     {/if}
 </section>
 
+{#snippet Temp(t: { label: string; celsius: number; max_celsius: number | null; critical_celsius: number | null })}
+    {@const limit = t.critical_celsius ?? 100}
+    {@const pct = Math.min(100, Math.max(0, (t.celsius / limit) * 100))}
+    <div class="temp">
+        <div class="temp-head">
+            <span class="temp-label">{t.label}</span>
+            <span class="temp-val">{t.celsius.toFixed(0)}°C</span>
+        </div>
+        <div
+            class="bar"
+            role="progressbar"
+            aria-valuenow={t.celsius}
+            aria-valuemin="0"
+            aria-valuemax={limit}
+            aria-label="{t.label} {t.celsius.toFixed(0)}°C"
+        >
+            <div
+                class="fill"
+                class:high={pct >= 90}
+                class:mid={pct >= 70 && pct < 90}
+                style:width="{pct}%"
+            ></div>
+        </div>
+        <p class="sub">
+            {#if t.max_celsius !== null}max {t.max_celsius.toFixed(0)}°C{/if}
+            {#if t.critical_celsius !== null}
+                · crit {t.critical_celsius.toFixed(0)}°C{/if}
+        </p>
+    </div>
+{/snippet}
+
 {#snippet Bar({ percent }: { percent: number })}
     <div
         class="bar"
@@ -400,6 +422,17 @@
     .temp + .temp {
         margin-top: var(--space-3);
     }
+    .more-temps {
+        margin-top: var(--space-3);
+    }
+    .more-temps summary {
+        cursor: pointer;
+        font-size: var(--font-sm);
+        color: var(--text-muted);
+    }
+    .more-temps .temp:first-of-type {
+        margin-top: var(--space-3);
+    }
     .temp-head {
         display: flex;
         justify-content: space-between;