chore: initial scaffolding for SynthesisAgent.OpenclawPlugin

OpenClaw plugin that manages long-lived interactive Claude Code processes
per OpenClaw session. Process manager + session-mapping persistence +
bridge WebSocket server skeleton.

Will be rewritten to follow the contractor-agent HTTP model-provider pattern
(register as `synthesis-claude-bridge` provider, receive /v1/chat/completions,
dispatch to channel notification on the bound Claude process). See parent
repo's STATUS.md for the punch list.

index.ts

@@ -0,0 +1,68 @@
+import { definePluginEntry } from 'openclaw/plugin-sdk/plugin-entry'
+import type { OpenClawPluginApi } from 'openclaw/plugin-sdk/core'
+import { normalizeConfig, type SynthesisConfig } from './core/config.js'
+import { ProcessManager } from './core/process-manager.js'
+import { SessionMapping } from './core/session-mapping.js'
+import { startBridgeServer } from './web/bridge-server.js'
+import { registerCli } from './core/cli.js'
+
+// All long-lived state lives on globalThis so OpenClaw hot-reloads don't kill
+// running Claude processes (mirrors contractor-agent's convention).
+const _G = globalThis as Record<string, unknown>
+const PM_KEY = '_synthesisProcessManager'
+const SERVER_KEY = '_synthesisBridgeServer'
+const MAPPING_KEY = '_synthesisSessionMapping'
+
+export default definePluginEntry({
+  id: 'synthesis-agent',
+  name: 'SynthesisAgent',
+  description: 'Manages long-lived Claude Code processes per OpenClaw session',
+
+  register(api: OpenClawPluginApi): void {
+    const config: SynthesisConfig = normalizeConfig(api.pluginConfig)
+
+    // ── Reuse existing state across hot reload ─────────────────────────────
+    let mapping = _G[MAPPING_KEY] as SessionMapping | undefined
+    if (!mapping) {
+      mapping = new SessionMapping(config.mappingDbPath)
+      _G[MAPPING_KEY] = mapping
+    }
+
+    let pm = _G[PM_KEY] as ProcessManager | undefined
+    if (!pm) {
+      pm = new ProcessManager({ config, mapping })
+      _G[PM_KEY] = pm
+    }
+
+    // Existing bridge server: leave it alone.
+    if (!_G[SERVER_KEY]) {
+      startBridgeServer({ config, mapping, processManager: pm })
+        .then(server => { _G[SERVER_KEY] = server })
+        .catch(err => {
+          api.logger?.error?.('synthesis: bridge server failed to start', err)
+        })
+    }
+
+    // ── Wire to OpenClaw inbound event bus ─────────────────────────────────
+    // TODO: subscribe to api.events / api.channels.onInbound (exact API TBD).
+    // Each inbound message arrives with an openclaw_session_id; we forward to
+    // the process manager, which spawns/resumes claude as needed and pushes
+    // the message into its plugin's bridge socket.
+    //
+    //   api.channels.onInbound((evt) => {
+    //     pm.deliverInbound(evt.openclawSessionId, evt)
+    //   })
+    //
+    // Similarly for permission replies.
+
+    registerCli(api, { processManager: pm, mapping, config })
+
+    api.lifecycle?.onShutdown?.(async () => {
+      const server = _G[SERVER_KEY] as Awaited<ReturnType<typeof startBridgeServer>> | undefined
+      await server?.close?.()
+      delete _G[SERVER_KEY]
+      await pm!.shutdown()
+      delete _G[PM_KEY]
+    })
+  },
+})