mesh-llm: C1 MeshComputeSettingsCard

desktop/src/features/settings/ui/MeshComputeSettingsCard.tsx (new):
- Toggle: 'Share this machine's compute' (master switch).
- Three numeric inputs: max VRAM (MB), max RAM (MB), concurrent peers.
  Empty = no cap, validated to non-negative integers.
- Displays the local iroh endpoint id (canonical Display form) so the
  user knows which device identity is publishing.
- All state persisted through the mesh_set_sharing_prefs Tauri command;
  loads via mesh_get_sharing_prefs + mesh_get_endpoint_id on mount.
- Error and saving states surfaced inline.

Registered as a new 'compute' SettingsSection in SettingsPanels.tsx
between 'agents' and 'channel-templates', with a Cpu icon. Reached
through the existing avatar-menu -> Settings flow (no popover
restructuring needed for the MVP).

desktop typecheck (tsc --noEmit): clean.
desktop biome check: clean.

UX (matches Tyler's [1]):
- avatar bottom-left -> ProfilePopover -> Settings -> Share compute
- one switch + three caps; the offering side decides everything.

Signed-off-by: Tyler Longwell <109685178+tlongwell-block@users.noreply.github.com>
Co-authored-by: Dawn (sprout agent) <c6237ef84fa537c78dcee78efd2d4e59f728859c7f194da42ac51ededfa0be05@sprout-oss.stage.blox.sqprod.co>

desktop/src/features/settings/ui/MeshComputeSettingsCard.tsx

@@ -0,0 +1,233 @@
+import * as React from "react";
+import { invoke } from "@tauri-apps/api/core";
+import { Cpu } from "lucide-react";
+
+import { Switch } from "@/shared/ui/switch";
+import { Input } from "@/shared/ui/input";
+
+// ---------------------------------------------------------------------------
+// Types matching the Rust mesh_llm::ComputeSharingPrefs / ResourceCaps shape.
+// ---------------------------------------------------------------------------
+
+interface ResourceCaps {
+  max_vram_mb: number | null;
+  max_ram_mb: number | null;
+  max_concurrency: number | null;
+}
+
+interface ModelOffer {
+  id: string;
+  label?: string | null;
+  context_tokens?: number | null;
+}
+
+interface ComputeSharingPrefs {
+  enabled: boolean;
+  caps: ResourceCaps;
+  models: ModelOffer[];
+  d_tag: string;
+}
+
+interface MeshEndpointInfo {
+  endpoint_id: string;
+}
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+/// Parse a string into Some(n) when it represents a positive integer, or
+/// None to clear the cap. Empty string also clears.
+function parseCap(raw: string): number | null {
+  if (raw.trim() === "") return null;
+  const n = Number.parseInt(raw, 10);
+  if (Number.isFinite(n) && n >= 0) return n;
+  return null;
+}
+
+function formatCap(value: number | null): string {
+  return value == null ? "" : String(value);
+}
+
+// ---------------------------------------------------------------------------
+// Card
+// ---------------------------------------------------------------------------
+
+export function MeshComputeSettingsCard() {
+  const [prefs, setPrefs] = React.useState<ComputeSharingPrefs | null>(null);
+  const [endpoint, setEndpoint] = React.useState<MeshEndpointInfo | null>(null);
+  const [error, setError] = React.useState<string | null>(null);
+  const [saving, setSaving] = React.useState(false);
+
+  // Load the persisted prefs + the iroh endpoint identity on mount.
+  React.useEffect(() => {
+    let cancelled = false;
+    (async () => {
+      try {
+        const [p, e] = await Promise.all([
+          invoke<ComputeSharingPrefs>("mesh_get_sharing_prefs"),
+          invoke<MeshEndpointInfo>("mesh_get_endpoint_id"),
+        ]);
+        if (!cancelled) {
+          setPrefs(p);
+          setEndpoint(e);
+        }
+      } catch (e) {
+        if (!cancelled) setError(String(e));
+      }
+    })();
+    return () => {
+      cancelled = true;
+    };
+  }, []);
+
+  const persist = React.useCallback(async (next: ComputeSharingPrefs) => {
+    setSaving(true);
+    setError(null);
+    try {
+      await invoke("mesh_set_sharing_prefs", { prefs: next });
+      setPrefs(next);
+    } catch (e) {
+      setError(String(e));
+    } finally {
+      setSaving(false);
+    }
+  }, []);
+
+  if (!prefs) {
+    return (
+      <section className="min-w-0" data-testid="settings-compute">
+        <div className="mb-3">
+          <h2 className="text-sm font-semibold tracking-tight">
+            Share compute
+          </h2>
+          <p className="text-sm text-muted-foreground">
+            {error ?? "Loading mesh-LLM preferences…"}
+          </p>
+        </div>
+      </section>
+    );
+  }
+
+  const updateCap = (field: keyof ResourceCaps, raw: string) => {
+    persist({
+      ...prefs,
+      caps: { ...prefs.caps, [field]: parseCap(raw) },
+    });
+  };
+
+  return (
+    <section className="min-w-0" data-testid="settings-compute">
+      <div className="mb-3 min-w-0">
+        <h2 className="text-sm font-semibold tracking-tight">Share compute</h2>
+        <p className="text-sm text-muted-foreground">
+          When enabled, other members of this relay can run agents on this
+          machine using the limits you set below. Your relay membership is the
+          only gate — there is no signup or external account.
+        </p>
+      </div>
+
+      {error ? (
+        <p className="mb-3 rounded bg-destructive/10 px-2 py-1 text-xs text-destructive">
+          {error}
+        </p>
+      ) : null}
+
+      <div className="flex flex-col gap-4">
+        {/* ── Master toggle ────────────────────────────────────────── */}
+        <div className="flex items-center justify-between gap-4">
+          <div className="min-w-0">
+            <label
+              className="text-sm font-medium"
+              htmlFor="mesh-compute-enabled"
+            >
+              Share this machine's compute
+            </label>
+            <p className="text-sm text-muted-foreground">
+              Publishes a kind:31990 compute-offer event when on; deletes it
+              when off.
+            </p>
+          </div>
+          <Switch
+            checked={prefs.enabled}
+            data-testid="mesh-compute-enabled-toggle"
+            disabled={saving}
+            id="mesh-compute-enabled"
+            onCheckedChange={(checked) =>
+              persist({ ...prefs, enabled: checked })
+            }
+          />
+        </div>
+
+        {/* ── Caps ─────────────────────────────────────────────────── */}
+        <fieldset className="flex flex-col gap-3" disabled={!prefs.enabled}>
+          <legend className="flex items-center gap-2 text-sm font-medium">
+            <Cpu className="h-4 w-4 text-muted-foreground" />
+            Limits per request
+          </legend>
+
+          <div className="grid grid-cols-3 gap-3">
+            <div>
+              <label
+                className="text-xs text-muted-foreground"
+                htmlFor="mesh-vram"
+              >
+                Max VRAM (MB)
+              </label>
+              <Input
+                data-testid="mesh-cap-vram"
+                id="mesh-vram"
+                inputMode="numeric"
+                onChange={(e) => updateCap("max_vram_mb", e.target.value)}
+                placeholder="No limit"
+                value={formatCap(prefs.caps.max_vram_mb)}
+              />
+            </div>
+            <div>
+              <label
+                className="text-xs text-muted-foreground"
+                htmlFor="mesh-ram"
+              >
+                Max RAM (MB)
+              </label>
+              <Input
+                data-testid="mesh-cap-ram"
+                id="mesh-ram"
+                inputMode="numeric"
+                onChange={(e) => updateCap("max_ram_mb", e.target.value)}
+                placeholder="No limit"
+                value={formatCap(prefs.caps.max_ram_mb)}
+              />
+            </div>
+            <div>
+              <label
+                className="text-xs text-muted-foreground"
+                htmlFor="mesh-concurrency"
+              >
+                Concurrent peers
+              </label>
+              <Input
+                data-testid="mesh-cap-concurrency"
+                id="mesh-concurrency"
+                inputMode="numeric"
+                onChange={(e) => updateCap("max_concurrency", e.target.value)}
+                placeholder="1"
+                value={formatCap(prefs.caps.max_concurrency)}
+              />
+            </div>
+          </div>
+        </fieldset>
+
+        {/* ── Identity ────────────────────────────────────────────── */}
+        {endpoint ? (
+          <div className="rounded border border-border/60 bg-muted/30 px-3 py-2 text-xs text-muted-foreground">
+            <span className="font-medium text-foreground">
+              This device's iroh endpoint:
+            </span>{" "}
+            <code className="break-all">{endpoint.endpoint_id}</code>
+          </div>
+        ) : null}
+      </div>
+    </section>
+  );
+}

desktop/src/features/settings/ui/SettingsPanels.tsx

@@ -3,6 +3,7 @@ import {
   BellRing,
   Bot,
   Check,
+  Cpu,
   Download,
   Keyboard,
   LayoutTemplate,
@@ -31,6 +32,7 @@ import { SYNTAX_THEMES, isLightTheme } from "@/shared/theme/theme-loader";
 import { ChannelTemplatesSettingsCard } from "./ChannelTemplatesSettingsCard";
 import { DoctorSettingsPanel } from "./DoctorSettingsPanel";
 import { KeyboardShortcutsCard } from "./KeyboardShortcutsCard";
+import { MeshComputeSettingsCard } from "./MeshComputeSettingsCard";
 import { MobilePairingCard } from "./MobilePairingCard";
 import { NotificationSettingsCard } from "./NotificationSettingsCard";
 import { PreventSleepSettingsCard } from "./PreventSleepSettingsCard";
@@ -41,6 +43,7 @@ export type SettingsSection =
   | "profile"
   | "notifications"
   | "agents"
+  | "compute"
   | "channel-templates"
   | "appearance"
   | "shortcuts"
@@ -87,6 +90,11 @@ export const settingsSections: SettingsSectionDescriptor[] = [
     label: "Agents",
     icon: Bot,
   },
+  {
+    value: "compute",
+    label: "Share compute",
+    icon: Cpu,
+  },
   {
     value: "channel-templates",
     label: "Templates",
@@ -282,6 +290,8 @@ export function renderSettingsSection(
       );
     case "agents":
       return <PreventSleepSettingsCard />;
+    case "compute":
+      return <MeshComputeSettingsCard />;
     case "channel-templates":
       return <ChannelTemplatesSettingsCard />;
     case "appearance":