Switch to prefixed IDs and tell agents which Mac a message came from

internal/agents/snapshots.go

@@ -12,6 +12,7 @@ import (
 	"g.fc.run/ai/byre/internal/api"
 	"g.fc.run/ai/byre/internal/claude"
 	"g.fc.run/ai/byre/internal/git"
+	"g.fc.run/ai/byre/internal/ids"
 	"g.fc.run/ai/byre/internal/mcp"
 	"g.fc.run/ai/byre/internal/store"
 )
@@ -165,7 +166,7 @@ func (m *Manager) takeSnapshot(ctx context.Context, t snapTarget, trigger api.Sn
 	}
 
 	snap := api.Snapshot{
-		Id:             store.NewID(),
+		Id:             ids.New(ids.Snapshot),
 		TaskId:         t.taskID,
 		AgentSessionId: t.sessionID,
 		N:              n,