diff --git a/helm/siclaw/templates/gateway-deployment.yaml b/helm/siclaw/templates/gateway-deployment.yaml
index 72872e89..27f92ab8 100644
--- a/helm/siclaw/templates/gateway-deployment.yaml
+++ b/helm/siclaw/templates/gateway-deployment.yaml
@@ -16,6 +16,17 @@ spec:
         {{- include "siclaw.selectorLabels" (dict "ctx" . "component" "gateway") | nindent 8 }}
     spec:
       serviceAccountName: {{ include "siclaw.fullname" . }}-gateway
+      {{- if gt (int .Values.gateway.replicas) 1 }}
+      affinity:
+        podAntiAffinity:
+          preferredDuringSchedulingIgnoredDuringExecution:
+            - weight: 100
+              podAffinityTerm:
+                labelSelector:
+                  matchLabels:
+                    {{- include "siclaw.selectorLabels" (dict "ctx" . "component" "gateway") | nindent 20 }}
+                topologyKey: kubernetes.io/hostname
+      {{- end }}
       containers:
         - name: gateway
           image: {{ include "siclaw.image" (dict "component" "gateway" "ctx" .) }}
@@ -52,6 +63,14 @@ spec:
             {{- end }}
             - name: SICLAW_SKILLS_DIR
               value: ".siclaw/skills"
+            - name: SICLAW_POD_NAME
+              valueFrom:
+                fieldRef:
+                  fieldPath: metadata.name
+            - name: SICLAW_POD_IP
+              valueFrom:
+                fieldRef:
+                  fieldPath: status.podIP
             - name: SICLAW_GATEWAY_HOSTNAME
               value: "{{ include "siclaw.fullname" . }}-gateway.{{ .Values.namespace }}.svc.cluster.local"
             {{- if .Values.database.existingSecret.name }}
diff --git a/helm/siclaw/templates/gateway-service.yaml b/helm/siclaw/templates/gateway-service.yaml
index ba377701..83a32be0 100644
--- a/helm/siclaw/templates/gateway-service.yaml
+++ b/helm/siclaw/templates/gateway-service.yaml
@@ -7,6 +7,12 @@ metadata:
     {{- include "siclaw.labels" (dict "ctx" . "component" "gateway") | nindent 4 }}
 spec:
   type: {{ .Values.gateway.service.type }}
+  {{- if gt (int .Values.gateway.replicas) 1 }}
+  sessionAffinity: ClientIP
+  sessionAffinityConfig:
+    clientIP:
+      timeoutSeconds: {{ .Values.gateway.sessionAffinityTimeout | default 10800 }}
+  {{- end }}
   ports:
     - port: {{ .Values.gateway.service.port }}
       targetPort: http
diff --git a/helm/siclaw/values.yaml b/helm/siclaw/values.yaml
index 46b3d9ee..6d2137b8 100644
--- a/helm/siclaw/values.yaml
+++ b/helm/siclaw/values.yaml
@@ -12,6 +12,7 @@ image:
 # -- Gateway
 gateway:
   replicas: 1
+  sessionAffinityTimeout: 10800  # 3 hours, only effective when replicas > 1
   service:
     type: NodePort
     port: 80
diff --git a/src/gateway-main.ts b/src/gateway-main.ts
index 5c11eeff..98c02730 100644
--- a/src/gateway-main.ts
+++ b/src/gateway-main.ts
@@ -1,4 +1,5 @@
 import type http from "node:http";
+import os from "node:os";
 import { loadGatewayConfig } from "./gateway/config.js";
 import { startGateway } from "./gateway/server.js";
 import { AgentBoxManager, LocalSpawner, K8sSpawner, ProcessSpawner } from "./gateway/agentbox/index.js";
@@ -56,12 +57,18 @@ try {
   // Internal plugin not available — running in open-source mode
 }
 
+// Instance ID for multi-replica cron coordination (K8s mode only)
+const instanceId = useK8s
+  ? (process.env.SICLAW_POD_NAME || os.hostname())
+  : undefined;
+
 // Start HTTP + WebSocket server
 const gateway = await startGateway({
   config,
   agentBoxManager,
   spawner,
   extraHttpHandlers,
+  instanceId,
 });
 
 // --- Channel subsystem ---
diff --git a/src/gateway/cron/cron-service.ts b/src/gateway/cron/cron-service.ts
index cbd48e6d..6e5c53bc 100644
--- a/src/gateway/cron/cron-service.ts
+++ b/src/gateway/cron/cron-service.ts
@@ -4,6 +4,11 @@
  * Replaces the standalone cron process. Runs timers directly in the
  * Gateway process and calls configRepo for DB access (no HTTP proxy).
  * Job execution delegates to /api/internal/agent-prompt on localhost.
+ *
+ * Multi-replica coordination: when `instanceId` is set (K8s mode),
+ * each replica registers as a cron instance, heartbeats, and only
+ * schedules jobs assigned to it. Single-instance mode (local/dev)
+ * skips coordination and schedules all active jobs.
  */
 
 import crypto from "node:crypto";
@@ -20,10 +25,15 @@ const SESSION_SOFT_DELETE_DAYS = 180;
 const SESSION_HARD_DELETE_DAYS = 30;
 const STATS_RETENTION_DAYS = 90;
 
+// Coordination constants (tuned values from old CronCoordinator — commit 7c41fa6)
+const RECONCILE_INTERVAL_MS = 15_000;  // 15s (includes heartbeat)
+const DEAD_THRESHOLD_MS = 30_000;      // 30s = 2× reconcile interval
+
 export type SendToUserFn = (userId: string, event: string, payload: Record<string, unknown>) => void;
 
 export class CronService {
   readonly scheduler: CronScheduler;
+  readonly instanceId: string | undefined;
   /** Channel notification callback — set by gateway-main after construction */
   onNotify?: (data: { userId: string; jobName: string; result: string; resultText: string; error?: string }) => void;
 
@@ -34,30 +44,41 @@ export class CronService {
   private staleLockTimer: NodeJS.Timeout | null = null;
   private purgeTimer: NodeJS.Timeout | null = null;
   private sessionPurgeTimer: NodeJS.Timeout | null = null;
+  private reconcileTimer: NodeJS.Timeout | null = null;
 
   constructor(opts: {
     configRepo: ConfigRepository;
     notifRepo: NotificationRepository;
     sendToUser: SendToUserFn;
     gatewayPort: number;
+    instanceId?: string;
   }) {
     this.configRepo = opts.configRepo;
     this.notifRepo = opts.notifRepo;
     this.sendToUser = opts.sendToUser;
     this.gatewayPort = opts.gatewayPort;
+    this.instanceId = opts.instanceId;
     this.scheduler = new CronScheduler((job) => this.execute(job));
   }
 
   /** Load all active jobs and start background timers */
   async start(): Promise<void> {
-    // Load all active jobs
-    const jobs = await this.configRepo.listAllActiveCronJobs();
-    for (const job of jobs) {
-      this.scheduler.addOrUpdate(job as CronJobRow);
+    // Register this instance (multi-replica mode only)
+    if (this.instanceId) {
+      const endpoint = `http://${process.env.SICLAW_POD_IP || "localhost"}:${this.gatewayPort}`;
+      await this.configRepo.registerCronInstance(this.instanceId, endpoint);
     }
-    console.log(`[cron-service] Loaded ${jobs.length} active jobs`);
 
-    // Stale lock cleanup every 6 minutes
+    // Initial reconcile — loads jobs (all in single-instance, assigned in multi)
+    await this.reconcile();
+
+    // Reconcile loop (15s — includes heartbeat in multi-replica mode)
+    if (this.instanceId) {
+      this.reconcileTimer = setInterval(() => this.reconcileTick(), RECONCILE_INTERVAL_MS);
+      this.reconcileTimer.unref();
+    }
+
+    // Stale lock cleanup every 6 minutes (single-instance keeps this too)
     this.staleLockTimer = setInterval(async () => {
       try {
         await this.configRepo.clearStaleLocks(STALE_LOCK_CLEANUP_MS);
@@ -77,9 +98,99 @@ export class CronService {
     this.sessionPurgeTimer = setInterval(() => this.purgeSessions(), PURGE_INTERVAL_MS);
     this.sessionPurgeTimer.unref();
 
-    console.log("[cron-service] Started");
+    console.log(`[cron-service] Started${this.instanceId ? ` (instance=${this.instanceId})` : ""}`);
+  }
+
+  // ── Coordination (ported from old CronCoordinator — commit 7c41fa6) ───
+
+  /** Main reconcile loop — single-instance fast path or full coordination */
+  private async reconcile(): Promise<void> {
+    if (!this.instanceId) {
+      // Single-instance: schedule everything (backward compatible)
+      const jobs = await this.configRepo.listAllActiveCronJobs();
+      for (const job of jobs) this.scheduler.addOrUpdate(job as CronJobRow);
+      console.log(`[cron-service] Loaded ${jobs.length} active jobs`);
+      return;
+    }
+
+    // 0. Heartbeat
+    await this.configRepo.updateHeartbeat(this.instanceId, this.scheduler.jobCount);
+
+    // 1. Clear stale execution locks
+    await this.configRepo.clearStaleLocks(STALE_LOCK_CLEANUP_MS);
+
+    // 2. Detect dead instances → reassign orphaned jobs
+    const dead = await this.configRepo.getDeadInstances(DEAD_THRESHOLD_MS);
+    for (const inst of dead) {
+      const target = await this.configRepo.getLeastLoadedInstance(DEAD_THRESHOLD_MS);
+      if (target) {
+        await this.configRepo.reassignOrphanedJobs(inst.instanceId, target.instanceId);
+        console.log(`[cron-service] Reassigned jobs from dead instance ${inst.instanceId} → ${target.instanceId}`);
+      }
+      await this.configRepo.deleteInstance(inst.instanceId);
+    }
+
+    // 3. Cancel stale local timers (DB deleted/paused/reassigned)
+    await this.cancelStaleJobs();
+
+    // 4. Claim unassigned jobs (only if we are least-loaded)
+    await this.claimUnassignedJobs();
+
+    // 5. Sync: load DB-assigned jobs missing from local scheduler
+    await this.syncAssignedJobs();
+  }
+
+  /** Claim unassigned active jobs — only if this instance is least-loaded */
+  private async claimUnassignedJobs(): Promise<void> {
+    const unassigned = await this.configRepo.getUnassignedActiveJobs();
+    if (!unassigned.length) return;
+
+    for (const job of unassigned) {
+      const leastLoaded = await this.configRepo.getLeastLoadedInstance(DEAD_THRESHOLD_MS);
+      if (!leastLoaded) break;
+      if (leastLoaded.instanceId !== this.instanceId!) break; // not least-loaded, let another instance claim
+
+      const claimed = await this.configRepo.claimUnassignedJob(job.id, this.instanceId!);
+      if (!claimed) continue; // another instance claimed first
+
+      await this.configRepo.updateHeartbeat(this.instanceId!, this.scheduler.jobCount + 1);
+      this.scheduler.addOrUpdate(job as CronJobRow);
+      console.log(`[cron-service] Claimed job ${job.id} (${job.name})`);
+    }
+  }
+
+  /** Cancel local timers for jobs that are deleted/paused/reassigned in DB */
+  private async cancelStaleJobs(): Promise<void> {
+    for (const jobId of this.scheduler.scheduledJobIds) {
+      const dbJob = await this.configRepo.getCronJobById(jobId);
+      if (!dbJob || dbJob.status !== "active" || dbJob.assignedTo !== this.instanceId) {
+        this.scheduler.cancel(jobId);
+      }
+    }
   }
 
+  /** Load DB-assigned jobs that are missing from local scheduler */
+  private async syncAssignedJobs(): Promise<void> {
+    const dbJobs = await this.configRepo.listCronJobsByInstance(this.instanceId!);
+    const scheduled = new Set(this.scheduler.scheduledJobIds);
+    for (const job of dbJobs) {
+      if (!scheduled.has(job.id)) {
+        this.scheduler.addOrUpdate(job as CronJobRow);
+      }
+    }
+  }
+
+  /** Timer callback for reconcile loop */
+  private async reconcileTick(): Promise<void> {
+    try {
+      await this.reconcile();
+    } catch (err) {
+      console.warn("[cron-service] Reconcile failed:", err instanceof Error ? err.message : err);
+    }
+  }
+
+  // ── Job execution ─────────────────────────────────────────────────────
+
   /** Execute a single cron job */
   private async execute(job: CronJobRow): Promise<void> {
     // Re-validate from DB
@@ -89,6 +200,13 @@ export class CronService {
       return;
     }
 
+    // In multi-replica mode, verify we still own this job
+    if (this.instanceId && current.assignedTo !== this.instanceId) {
+      console.log(`[cron-service] Job ${job.id} reassigned to ${current.assignedTo}, skipping`);
+      this.scheduler.cancel(job.id);
+      return;
+    }
+
     // Soft concurrent-execution limit — skip this run, retry next cycle
     const executing = await this.configRepo.countCurrentlyExecutingJobs();
     if (executing >= CRON_LIMITS.MAX_CONCURRENT_EXECUTIONS) {
@@ -225,8 +343,8 @@ export class CronService {
     this.scheduler.cancel(jobId);
   }
 
-  /** Stop all timers and clean up */
-  stop(): void {
+  /** Stop all timers and clean up. Deregisters instance in multi-replica mode. */
+  async stop(): Promise<void> {
     this.scheduler.stop();
     if (this.staleLockTimer) {
       clearInterval(this.staleLockTimer);
@@ -240,6 +358,21 @@ export class CronService {
       clearInterval(this.sessionPurgeTimer);
       this.sessionPurgeTimer = null;
     }
+    if (this.reconcileTimer) {
+      clearInterval(this.reconcileTimer);
+      this.reconcileTimer = null;
+    }
+
+    // Deregister instance and release jobs (multi-replica only)
+    if (this.instanceId) {
+      try {
+        await this.configRepo.releaseInstanceJobs(this.instanceId);
+        await this.configRepo.deleteInstance(this.instanceId);
+      } catch (err) {
+        console.warn("[cron-service] Deregister failed:", err instanceof Error ? err.message : err);
+      }
+    }
+
     console.log("[cron-service] Stopped");
   }
 
diff --git a/src/gateway/server.ts b/src/gateway/server.ts
index ffc1ab81..100f4fc9 100644
--- a/src/gateway/server.ts
+++ b/src/gateway/server.ts
@@ -122,10 +122,12 @@ export interface StartGatewayOptions {
   spawner?: import("./agentbox/spawner.js").BoxSpawner;
   extraRpcMethods?: Map<string, RpcHandler>;
   extraHttpHandlers?: Map<string, (req: http.IncomingMessage, res: http.ServerResponse) => void>;
+  /** Pod name for multi-replica cron coordination. undefined = single-instance mode. */
+  instanceId?: string;
 }
 
 export async function startGateway(opts: StartGatewayOptions): Promise<GatewayServer> {
-  const { config, agentBoxManager, spawner, extraRpcMethods, extraHttpHandlers } = opts;
+  const { config, agentBoxManager, spawner, extraRpcMethods, extraHttpHandlers, instanceId } = opts;
 
   // Track users with active SSE prompt streams (web UI)
   const activePromptUsers = new Set<string>();
@@ -163,7 +165,7 @@ export async function startGateway(opts: StartGatewayOptions): Promise<GatewaySe
 
   // In-process cron service (replaces standalone cron process)
   const cronService = (configRepo && notifRepo)
-    ? new CronService({ configRepo, notifRepo, sendToUser, gatewayPort: config.port })
+    ? new CronService({ configRepo, notifRepo, sendToUser, gatewayPort: config.port, instanceId })
     : null;
 
   // System config repo (used by JWT, SSO, cert-manager, metrics cache, etc.)
@@ -302,6 +304,20 @@ export async function startGateway(opts: StartGatewayOptions): Promise<GatewaySe
   }
 
   await refreshSsoCache();
+
+  // Config cache TTL — poll DB every 30s so non-local replicas pick up changes
+  const CONFIG_CACHE_TTL_MS = 30_000;
+  const configCacheTimer = setInterval(async () => {
+    try {
+      await refreshCspCache();
+      await refreshMetricsConfig();
+      await refreshSsoCache();
+    } catch (err) {
+      console.warn("[gateway] Config cache refresh failed:", err instanceof Error ? err.message : err);
+    }
+  }, CONFIG_CACHE_TTL_MS);
+  configCacheTimer.unref();
+
   if (cachedOAuth2Config) {
     // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion -- TS can't narrow let vars captured by closures
     const cfg = cachedOAuth2Config as OAuth2Config;
@@ -1188,7 +1204,8 @@ export async function startGateway(opts: StartGatewayOptions): Promise<GatewaySe
     buildCredentialPayload,
     agentBoxTlsOptions,
     async close() {
-      cronService?.stop();
+      clearInterval(configCacheTimer);
+      await cronService?.stop();
       bindCodeStore.dispose();
       await agentBoxManager.cleanup();
       for (const ws of clients) {