fix(heartbeat): evitar versoes desnecessarias comparando dados antes de atualizar

- Compara inventory/metrics com valores atuais antes de incluir no patch
- Usa JSON.stringify para comparacao eficiente de objetos
- Filtra campos de metadata que realmente mudaram
- Evita criacao de versoes quando heartbeat envia dados identicos

Isso previne o acumulo de versoes no Convex que causava OOM.

Reducao de memoria apos limpeza manual:
- DB: 450MB -> 16MB (96%)
- RAM: 7GB -> 189MB (97%)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

convex/machines.ts

@@ -854,20 +854,44 @@ export const heartbeat = mutation({
       await ctx.db.insert("machineHeartbeats", { machineId: machine._id, lastHeartbeatAt: now })
     }
 
-    // 2. Preparar patch de metadata (se houver mudancas)
+    // 2. Preparar patch de metadata (se houver mudancas REAIS)
+    // IMPORTANTE: So incluimos no patch se os dados realmente mudaram
+    // Isso evita criar versoes desnecessarias do documento machines
     const metadataPatch: Record<string, unknown> = {}
+    const currentMetadata = (machine.metadata ?? {}) as Record<string, unknown>
+
     if (args.metadata && typeof args.metadata === "object") {
-      Object.assign(metadataPatch, args.metadata as Record<string, unknown>)
+      // Filtrar apenas campos que realmente mudaram
-    }
+      const incomingMeta = args.metadata as Record<string, unknown>
-    const remoteAccessSnapshot = metadataPatch["remoteAccessSnapshot"]
+      for (const key of Object.keys(incomingMeta)) {
-    if (remoteAccessSnapshot !== undefined) {
+        if (key !== "inventory" && key !== "metrics" && key !== "remoteAccessSnapshot") {
-      delete metadataPatch["remoteAccessSnapshot"]
+          if (JSON.stringify(incomingMeta[key]) !== JSON.stringify(currentMetadata[key])) {
+            metadataPatch[key] = incomingMeta[key]
+          }
+        }
+      }
     }
+
+    const remoteAccessSnapshot = (args.metadata as Record<string, unknown> | undefined)?.["remoteAccessSnapshot"]
+
+    // Inventory: so incluir se realmente mudou
     if (args.inventory && typeof args.inventory === "object") {
-      metadataPatch.inventory = mergeInventory(metadataPatch.inventory, args.inventory as Record<string, unknown>)
+      const currentInventory = currentMetadata.inventory as Record<string, unknown> | undefined
+      const newInventoryStr = JSON.stringify(args.inventory)
+      const currentInventoryStr = JSON.stringify(currentInventory ?? {})
+      if (newInventoryStr !== currentInventoryStr) {
+        metadataPatch.inventory = mergeInventory(currentInventory, args.inventory as Record<string, unknown>)
+      }
     }
+
+    // Metrics: so incluir se realmente mudou
     if (args.metrics && typeof args.metrics === "object") {
-      metadataPatch.metrics = args.metrics as Record<string, unknown>
+      const currentMetrics = currentMetadata.metrics as Record<string, unknown> | undefined
+      const newMetricsStr = JSON.stringify(args.metrics)
+      const currentMetricsStr = JSON.stringify(currentMetrics ?? {})
+      if (newMetricsStr !== currentMetricsStr) {
+        metadataPatch.metrics = args.metrics as Record<string, unknown>
+      }
     }
 
     // 3. Verificar se ha mudancas reais nos dados que justifiquem atualizar o documento machines