feat(fleet): native Mosaic backlog on @mosaicstack/db (atomic claim + TTL) (#657)

packages/mosaic/src/commands/fleet.ts

@@ -8,6 +8,7 @@ import * as readline from 'node:readline';
 import type { Command } from 'commander';
 import YAML from 'yaml';
 import { resolveCommsBlock } from '../fleet/comms-onboarding.js';
+import { registerFleetBacklogCommand } from './fleet-backlog.js';
 
 /**
  * A function that spawns a command with inherited stdio (TTY passthrough).
@@ -1700,6 +1701,11 @@ export function registerFleetCommand(program: Command, deps: FleetCommandDeps =
       console.log(`Removed ${name} from the fleet.`);
     });
 
+  // Mosaic-native backlog of record (card A4). Resolves the active --mosaic-home
+  // (parent flag) at call time so the embedded PGlite store lands under the same
+  // fleet/ directory as the roster and heartbeats.
+  registerFleetBacklogCommand(cmd, () => cmd.opts<{ mosaicHome: string }>().mosaicHome);
+
   return cmd;
 }