feat(header): opt-in GPU and CPU clock readings after CPU and MEM

.changeset/host-gpu-clocks.md

@@ -0,0 +1,5 @@
+---
+"aicodeman": minor
+---
+
+Opt-in header readings after CPU and MEM. **GPU Stats** adds three items: GPU load, graphics memory and the GPU clock (each only when the host reports it). **CPU MHz** adds the live CPU clock. Both chips are in Settings, Header & Panels and off by default. `GET /api/system/stats` takes `?gpu=1` and `?cpumhz=1`; nothing is read unless the browser asks, and a host without the sensor simply shows nothing. GPU: NVIDIA through `nvidia-smi`, AMD through sysfs, and inside WSL any vendor (Intel included) through the Windows performance counters, which give load and memory in use but no GPU clock. Inside WSL the CPU clock is also read from Windows, since WSL's own figure never changes. The header also keeps polling its stats when no session is open, so CPU and MEM no longer sit at `--` until one is.

config/test-suites.ts

@@ -26,6 +26,7 @@ export const BROWSER_TEST_GLOBS = [
   'test/tab-rail-search.browser.test.ts',
   'test/tab-focus.browser.test.ts',
   'test/session-sidebar-ux.browser.test.ts',
+  'test/header-host-sensors.browser.test.ts',
   'test/session-options-responsive.browser.test.ts',
   'test/inline-rename.test.ts',
   'test/opencode-resize.test.ts',

docs/architecture-invariants.md

@@ -1029,7 +1029,7 @@ With `classic` nothing is left behind: no headings, no breaks, no inline order,
 
 ### Header stats styles
 
-**Header stats styles** (`headerStatsStyle`, per-device, desktop only, default `compact`; Discussion #426 option G): how the WS readout, CPU, MEM and the plan-usage windows are drawn. `tiles` gives each its own label-over-value tile with a bar along the bottom edge; `compact` is two pills, WS / CPU / MEM and the plan windows, with a ring beside every value (stat rings accent, red past 80%; plan rings green, yellow or red); `classic` is the bars and `5H · 7D` chip as before. `data-header-stats` on `<html>` (pre-paint, then `applyHeaderStatsStyle()` from `applyHeaderVisibilitySettings()`) drives every rule; narrower than 768px and in a solo window it resolves to `classic`, because the stats are hidden there anyway and the moves below would otherwise reach the phone header.
+**Header stats styles** (`headerStatsStyle`, per-device, desktop only, default `compact`; Discussion #426 option G): how the WS readout, CPU, MEM and the plan-usage windows are drawn. `tiles` gives each its own label-over-value tile with a bar along the bottom edge; `compact` is two pills, WS / CPU / MEM and the plan windows, with a ring beside every value (stat rings accent, red past 80%; plan rings green, yellow or red); `classic` is the bars and `5H · 7D` chip as before. `data-header-stats` on `<html>` (pre-paint, then `applyHeaderStatsStyle()` from `applyHeaderVisibilitySettings()`) drives every rule; narrower than 768px and in a solo window it resolves to `classic`, because the stats are hidden there anyway and the moves below would otherwise reach the phone header. The opt-in host readings after MEM (GPU, VRAM, GPU MHz, CPU MHz: `.stat-item` elements that start `hidden` and are shown by `_updateHostSensors` in panels-ui.js) rely on `html[data-header-stats] .header-system-stats .stat-item[hidden]` in styles.css outranking the Tiles style's own `display` on `.stat-item`; keep that selector's specificity above any style rule that sets `display` on a stat item, or the hidden placeholders (`--%`) reappear.
 
 ⚠️ The clustered styles need the three elements contiguous, and the template keeps the classic order, so `applyHeaderStatsStyle()` MOVES `#connectionIndicator` into `#headerSystemStats` (first child) and `#planUsageChip` right after it, and `classic` moves them back to comment anchors it left at the template positions. Ids are unchanged, so every writer still finds them. ⚠️ The indicator joins the pill only while System Stats is shown: the pill is hidden with `display: none`, and the WS readout must not disappear with it.
 

docs/wiki/Settings-Reference.md

@@ -65,6 +65,15 @@ Manager, Attachments, File Viewer, Multi-monitor, Split, Tiles, Plan Usage, Life
 Project Insights, File Browser, Subagents, Approvals Inbox, Read My Mind, Ultracode Agents,
 Ultracode Windows, Cron.
 
+**Host readings** (opt-in, both off by default and per device): **GPU Stats** adds three items after CPU and MEM: GPU load, graphics memory and the GPU clock,
+and **CPU MHz** adds the live CPU clock. An item appears only when the
+host reports it, so a machine with no readable GPU shows nothing extra. Sources: `nvidia-smi` or the amdgpu
+sysfs files for the GPU; inside WSL, the Windows performance counters through `typeperf.exe`, which cover
+any vendor (an Intel GPU gives load and memory in use, but Windows publishes no clock for it, and its memory
+total is taken as half of Windows' RAM, the limit Windows applies to integrated GPUs); and
+`scaling_cur_freq`, `/proc/cpuinfo` or, inside WSL, the Windows `Processor Frequency` counter for the CPU
+clock. Nothing is read, and `nvidia-smi` and `typeperf.exe` are never run, while both are off.
+
 **Bottom bar** (below the chips): **Git status** shows a small indicator at the right of the
 bottom bar, off by default and per device. It reads `● N` uncommitted files, `↑ N` commits not
 pushed, `⚠ N` merge conflicts, `? N` repositories git could not read, or `✓` when everything is