## Summary
- Treat **shared PostgreSQL** (`DATABASE_URL`) as the multi-node durable
data plane; mesh HTTP is membership + optional auth, not task/settings
replication.
- **Peer exchange**: under Postgres backend mode, write queue is
**topology/auth-only**; non-topology pending rows fail rather than
replaying multi-leader task/settings payloads.
- **Mesh routes**: task-ID reserve/commit/abort always hit local shared
allocator rows (ignore remote `coordinatorNodeId`); mesh sync ignores
settings and only exchanges `authMaterial`.
- **Docs**: rewrite multi-project runbook, shared cluster protocol, and
architecture mesh sections for shared-Postgres + claims/leases.
## Context
Follows the SQLite→Postgres cutover. Multiple Fusion nodes can share one
external Postgres while keeping **per-node execution** (worktrees,
processes, claims via `central.task_claims`). Explicit non-goals remain:
scheduler failover and live process migration.
Plan:
`docs/plans/2026-07-15-001-refactor-mesh-shared-postgres-multinode-plan.md`
## Test plan
- [x] `pnpm --filter @fusion/engine exec vitest run
src/__tests__/peer-exchange-service.test.ts`
- [x] `pnpm --filter @fusion/dashboard exec vitest run
src/__tests__/mesh-routes.test.ts`
- [x] `pnpm --filter @fusion/core exec vitest run
src/__tests__/shared-mesh-state.test.ts`
- [ ] CI gate (lint/typecheck/build/gate)
- [ ] Manual (optional): two processes, same `DATABASE_URL`, create task
on A visible on B; settings change without mesh settings sync; claim
exclusivity
## Operator note
Multi-node shared board requires **external** `DATABASE_URL` on every
node. Default embedded Postgres is still single-host.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Improved multi-node deployments using shared PostgreSQL as the durable
source of execution state.
* Task ID reservation/commit/abort now run locally (no remote
coordinator forwarding).
* Mesh syncing now prioritizes topology visibility and authentication
material; settings replication is disabled in shared-Postgres mode.
* **Bug Fixes**
* Prevented task/settings replication over mesh HTTP in shared-Postgres
deployments.
* Refined lease ownership, recovery, and reconciliation to converge via
shared-database primitives.
* **Documentation**
* Updated architecture and shared-mesh protocol guidance, including
multi-node setup and lease/task-ID allocation behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
- Add core outage schema and mesh replay contract types, with CentralCore/CentralDB support for queue and snapshot persistence
- Expose runtime replay hooks in engine health monitoring and peer exchange paths to drive outage recovery flows
- Expand protocol and architecture docs for shared mesh replay behavior and finalized contract expectations
- Add regression tests across core and engine for queue sequencing, snapshot contracts, and replay integration
Fusion-Task-Id: FN-3960
Documents outage tolerance contracts across three architecture docs, with the bulk of changes in `docs/shared-mesh-protocol.md` plus minor additions to the main architecture and multi-project guides.
Fusion-Task-Id: FN-3455
The merge delivers two major features: mesh auth snapshot synchronization across nodes (FN-3707 steps 2/4/5, including core types, central-core plumbing, peer-exchange updates, and settings/node sync route helpers) and a bundled roadmap plugin with chat UX improvements (FN-3162, FN-3756, FN-3771, FN
Fusion-Task-Id: FN-3707
The merge normalizes button utility classes in AgentsView, swapping 12 lines of CSS class references for their standardized counterparts for consistency and maintainability.
Fusion-Task-Id: FN-3448
