feat(FN-3503): add project-node path mapping persistence APIs and schema

Adds project-node path mapping infrastructure in the core database layer (schema, migration backfill, and persistence APIs in `central-core.ts` and `central-db.ts`) with accompanying documentation. Also introduces a review-before-apply draft gate for agent onboarding and the agent detail view's mail

Fusion-Task-Id: FN-3503

docs/architecture.md

@@ -803,7 +803,7 @@ SQLite schema is initialized in `packages/core/src/db.ts` and uses:
 ### Central storage (multi-project)
 - **Central DB**: `~/.fusion/fusion-central.db`
 - Schema in `packages/core/src/central-db.ts`
-  - `projects`, `projectHealth`, `centralActivityLog`, `globalConcurrency`, `nodes`, `peerNodes`, `settingsSyncState`, `__meta`
+  - `projects`, `projectHealth`, `centralActivityLog`, `globalConcurrency`, `nodes`, `peerNodes`, `projectNodePathMappings`, `settingsSyncState`, `__meta`
 
 ### Memory files
 - OpenClaw-style memory workspace:
@@ -923,6 +923,7 @@ Multi-project orchestration spans core + engine.
   - Unified central activity feed
   - Global concurrency state
   - Node registry (`local` / `remote`)
+  - Per-project/per-node working-directory mappings (`projectNodePathMappings`)
 
 ### Engine orchestration
 - `HybridExecutor` (`packages/engine/src/hybrid-executor.ts`) is the top-level orchestrator

docs/multi-project.md

@@ -89,11 +89,14 @@ Projects can run with:
 
 ## Node Routing
 
-Multi-project deployments use two related node fields at different layers:
+Multi-project deployments use three related node/path records at different layers:
 
 1. **Project runtime placement** (`projects.nodeId` in `~/.fusion/fusion-central.db`)
    - Decides where a project runtime is hosted in multi-project orchestration.
-2. **Task dispatch default** (`defaultNodeId` in project settings)
+2. **Project working-directory mapping** (`projectNodePathMappings` in `~/.fusion/fusion-central.db`)
+   - Stores the absolute path for a project on each node (`projectId` + `nodeId` key).
+   - Local mappings are auto-created from `projects.path` at registration and kept in sync when local canonical path changes.
+3. **Task dispatch default** (`defaultNodeId` in project settings)
    - Decides where tasks route when they do not have a per-task override.
 
 These fields are intentionally distinct.
@@ -106,7 +109,7 @@ These fields are intentionally distinct.
 - `isolationMode: "in-process"` + remote `projects.nodeId` → `RemoteNodeRuntime`
 - `isolationMode: "in-process"` + local/unset/missing node assignment → `InProcessRuntime`
 
-So `projects.nodeId` is a **project host-node assignment**, not a per-task override.
+So `projects.nodeId` is a **project host-node assignment**, not a per-task override, and not the node-specific working-directory source of truth (that lives in `projectNodePathMappings`).
 
 ### Task routing defaults (`defaultNodeId` + `Task.nodeId`)
 

docs/settings-reference.md

@@ -343,8 +343,11 @@ Routing precedence for task dispatch is:
 
 Fusion also stores `projects.nodeId` in the **central registry database** (`~/.fusion/fusion-central.db`). That value is a multi-project runtime placement field used by `ProjectManager` (for selecting remote vs local project runtime), not the same setting as `defaultNodeId` task dispatch routing.
 
+Node-specific project working directories are persisted separately in central DB table `projectNodePathMappings` (`projectId` + `nodeId` + `path`). Do not treat `projects.nodeId` as the path source of truth.
+
 - `defaultNodeId` (project settings): task-level dispatch default
 - `projects.nodeId` (central registry): which node hosts the project runtime in multi-project mode
+- `projectNodePathMappings.path` (central registry): working-directory path for that project on that specific node
 
 See also:
 - [Task Management → Node Routing](./task-management.md#node-routing)