Add headless sync health rail stats journey stub for Phase 965.

Introduces runGuildMeshSyncHealthStatsJourney coverage and updates module docs so agentctl can verify the new non-breaking sync health stats extraction path.

README.md

@@ -275,6 +275,8 @@ Enable autonomous agents (and developers) to drive Pearcord like a real user wit
 
 Both modes use **`pearcord-ui-flow` `dispatchUiMessage`** — the same handler as `apps/pearcord/index.js`.
 
+**v0.8.932 (Phase 965):** Headless `runGuildMeshSyncHealthStatsJourney(guildId)` — sync health rail stats + diagnostics slice stub. Smoke: `npm run test:agentctl-guild-mesh-sync-health-stats-journey-stub`.
+
 **v0.8.931 (Phase 964):** Headless `runGuildMeshPartitionHealStatsJourney(guildId)` — partition heal stats + diagnostics embed keys stub. Smoke: `npm run test:agentctl-guild-mesh-partition-heal-stats-journey-stub`.
 
 **v0.8.930 (Phase 963):** Headless `runGuildMeshMemberPageStatsJourney(guildId)` — member page stats + roster sync keys stub. Smoke: `npm run test:agentctl-guild-mesh-member-page-stats-journey-stub`.

headless.js

@@ -1785,6 +1785,18 @@ class HeadlessSession {
     return { stats, heal }
   }
 
+  /** Journey stub: guild mesh sync health rail stats (Phase 965). */
+  async runGuildMeshSyncHealthStatsJourney (guildId) {
+    if (!this.platform) throw new Error('headless not started')
+    const gid = guildId || this.platform.guild?.guild?.id
+    if (!gid) throw new Error('no guild')
+    const stats = this.platform.getMeshStabilityStats(gid)
+    const health = this.platform.getGuildSyncHealth(gid)
+    const diagnostics = this.platform.exportGuildSyncDiagnostics(gid)
+    await this.refreshView()
+    return { stats, health, diagnostics }
+  }
+
   /** Journey stub: guild mesh topic pool snapshot (Phase 961). */
   async runGuildMeshTopicPoolSnapshotJourney (guildId) {
     if (!this.platform) throw new Error('headless not started')