fix: per-provider health checks in /llm/providers and status display

The /llm/providers endpoint now runs isAvailable() on each provider in
parallel and returns health status per provider. The status command shows
✓/✗ per provider based on actual availability, not just the fast tier.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/mcplocal/src/http/server.ts

@@ -140,19 +140,40 @@ export async function createHttpServer(
     }
   });
 
-  // LLM providers — list all registered providers with tier assignments
+  // LLM providers — list all registered providers with tier assignments and health
   app.get('/llm/providers', async (_request, reply) => {
     const registry = deps.providerRegistry;
     if (!registry) {
-      reply.code(200).send({ providers: [], tiers: { fast: [], heavy: [] } });
+      reply.code(200).send({ providers: [], tiers: { fast: [], heavy: [] }, health: {} });
       return;
     }
+
+    // Run isAvailable() on all providers in parallel (lightweight, no tokens burned)
+    const names = registry.list();
+    const healthChecks = await Promise.all(
+      names.map(async (name) => {
+        const provider = registry.get(name);
+        if (!provider) return { name, available: false };
+        try {
+          const available = await provider.isAvailable();
+          return { name, available };
+        } catch {
+          return { name, available: false };
+        }
+      }),
+    );
+    const health: Record<string, boolean> = {};
+    for (const check of healthChecks) {
+      health[check.name] = check.available;
+    }
+
     reply.code(200).send({
-      providers: registry.list(),
+      providers: names,
       tiers: {
         fast: registry.getTierProviders('fast'),
         heavy: registry.getTierProviders('heavy'),
       },
+      health,
     });
   });