feat(fabric): coalesce a split agent turn into ONE message (deterministic)

OpenClaw delivers an agent turn whose blocks are text -> thinking/tool
-> text via multiple inbound deliver() calls (a non-text block is a
delivery boundary), so one turn became N Fabric messages.

Fix: buffer deliver() segments per channel (src/coalesce.ts) and flush
them as ONE postMessage at a deterministic boundary — the finally after
dispatchInboundReplyWithBase() resolves, which provably runs only after
every deliver() of the turn (verified: deliver,deliver -> dispatch
returned -> flush). No hooks, no timers, no idle guessing. The
agent_end hook was rejected: it fires BEFORE deliver(). gateway_stop
flushes any leftover; a long safety timeout is a leak-guard only.
channels.fabric.coalesce=false restores raw per-segment posting.

Verified on local openclaw + Fabric with a fake text/thinking/text
model: single trigger -> exactly one merged message.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

dist/fabric/src/inbound.js

@@ -3,6 +3,8 @@ import { tmpdir } from 'node:os';
 import { join } from 'node:path';
 import { io } from 'socket.io-client';
 import { dispatchInboundReplyWithBase } from 'openclaw/plugin-sdk/inbound-reply-dispatch';
+import { resolveCoalesce } from './accounts.js';
+import { enqueueDelivery, flushFabricForChannel } from './coalesce.js';
 export class FabricInbound {
     core;
     cfg;
@@ -244,8 +246,16 @@ export class FabricInbound {
                     this.log.info(`fabric: deliver agent=${agentId} channel=${channelId} len=${text.length}`);
                     if (!text || !gt)
                         return;
-                    await this.client.postMessage(guild.endpoint, gt, channelId, text, session.user.id);
-                    this.log.info(`fabric: posted reply agent=${agentId} channel=${channelId}`);
+                    // Buffer segments; the merged message is posted right after
+                    // dispatch returns (the deterministic turn boundary, see the
+                    // finally below). Disable per channel: channels.fabric.coalesce.
+                    await enqueueDelivery({
+                        channelId,
+                        text,
+                        coalesce: resolveCoalesce(this.cfg),
+                        post: (t) => this.client.postMessage(guild.endpoint, gt, channelId, t, session.user.id),
+                        log: (m) => this.log.info(m),
+                    });
                 },
                 onRecordError: (err) => this.log.warn(`fabric: session record failed agent=${agentId}: ${String(err)}`),
                 onDispatchError: (err, info) => this.log.warn(`fabric: ${info.kind} dispatch failed agent=${agentId}: ${String(err)}`),
@@ -270,5 +280,12 @@ export class FabricInbound {
         catch (err) {
             this.log.warn(`fabric: dispatch failed agent=${agentId} channel=${channelId}: ${String(err)}`);
         }
+        finally {
+            // Deterministic per-turn boundary: dispatchInboundReplyWithBase only
+            // resolves AFTER every deliver() call of this turn has run, so the
+            // buffer now holds all segments — flush them as ONE Fabric message.
+            // No hooks, no timers, no idle guessing.
+            await flushFabricForChannel(channelId);
+        }
     }
 }