diff --git a/src/maint/maint.controller.ts b/src/maint/maint.controller.ts
index ae2f26c..e647f92 100644
--- a/src/maint/maint.controller.ts
+++ b/src/maint/maint.controller.ts
@@ -4,6 +4,7 @@ import { OzonetelAgentService } from '../ozonetel/ozonetel-agent.service';
 import { PlatformGraphqlService } from '../platform/platform-graphql.service';
 import { SessionService } from '../auth/session.service';
 import { SupervisorService } from '../supervisor/supervisor.service';
+import { AgentHistoryService, AgentEventType } from '../supervisor/agent-history.service';
 import { CallerResolutionService } from '../caller/caller-resolution.service';
 import { TelephonyConfigService } from '../config/telephony-config.service';
 
@@ -19,6 +20,7 @@ export class MaintController {
         private readonly session: SessionService,
         private readonly supervisor: SupervisorService,
         private readonly callerResolution: CallerResolutionService,
+        private readonly history: AgentHistoryService,
     ) {}
 
     @Post('force-ready')
@@ -421,4 +423,135 @@ export class MaintController {
             phones: { unique: resolvedByPhone.size, resolved: leadsResolved, errors: resolveErrors },
         };
     }
+
+    // Recompute durationS on existing AgentEvent rows using the per-category
+    // pairing logic. Fixes rows written before the slot-split fix where
+    // ACW_START clobbered CALL_START's pending entry. Also re-runs the
+    // session rollup for each affected date. Idempotent — only updates rows
+    // whose stored durationS differs from the recomputed value.
+    //
+    // POST /api/maint/backfill-agent-event-durations
+    // body: { date?: "YYYY-MM-DD" | "all" }  — default today IST
+    @Post('backfill-agent-event-durations')
+    async backfillAgentEventDurations(@Body() body: { date?: string }) {
+        const target = body?.date ?? this.todayIst();
+        this.logger.log(`[MAINT] Backfill AgentEvent durations — target=${target}`);
+
+        // Pull events for the range. If "all", no filter; otherwise scope to the IST day.
+        let events = await this.fetchAgentEventsForBackfill(target);
+        if (events.length === 0) {
+            return { status: 'ok', scanned: 0, patched: 0, skipped: 0, dates: [] };
+        }
+        this.logger.log(`[MAINT] Fetched ${events.length} AgentEvent rows`);
+
+        // Group by agent, sort by eventAt ascending.
+        const byAgent = new Map<string, typeof events>();
+        for (const e of events) {
+            const k = e.agentId;
+            if (!k) continue;
+            if (!byAgent.has(k)) byAgent.set(k, []);
+            byAgent.get(k)!.push(e);
+        }
+        for (const list of byAgent.values()) {
+            list.sort((a, b) => new Date(a.eventAt).getTime() - new Date(b.eventAt).getTime());
+        }
+
+        // Per-category slot pairing, same logic as the live ingest.
+        const slotForStart = (t: AgentEventType): 'pause' | 'call' | 'acw' | null =>
+            t === 'PAUSE' ? 'pause' : t === 'CALL_START' ? 'call' : t === 'ACW_START' ? 'acw' : null;
+        const slotForEnd = (t: AgentEventType): 'pause' | 'call' | 'acw' | null =>
+            t === 'RESUME' ? 'pause' : t === 'CALL_END' ? 'call' : t === 'ACW_END' ? 'acw' : null;
+
+        let patched = 0;
+        let skipped = 0;
+        const affectedDates = new Set<string>();
+
+        for (const [agentId, agentEvents] of byAgent) {
+            const pending: { pause?: number; call?: number; acw?: number } = {};
+            for (const e of agentEvents) {
+                const eventMs = new Date(e.eventAt).getTime();
+                const endSlot = slotForEnd(e.eventType);
+                const startSlot = slotForStart(e.eventType);
+
+                let computed: number | null = null;
+
+                if (endSlot) {
+                    const at = pending[endSlot];
+                    if (at !== undefined) {
+                        computed = Math.max(0, Math.round((eventMs - at) / 1000));
+                        delete pending[endSlot];
+                    }
+                } else if (startSlot) {
+                    pending[startSlot] = eventMs;
+                } else if (e.eventType === 'READY' || e.eventType === 'LOGOUT') {
+                    delete pending.pause;
+                    delete pending.call;
+                    delete pending.acw;
+                }
+
+                // Only patch END events that now have a computed duration
+                // different from what's stored.
+                if (endSlot && computed !== null && computed !== (e.durationS ?? null)) {
+                    try {
+                        await this.platform.query<any>(
+                            `mutation { updateAgentEvent(id: "${e.id}", data: { durationS: ${computed} }) { id } }`,
+                        );
+                        patched++;
+                        const datePart = (e.eventAt ?? '').slice(0, 10);
+                        if (datePart) affectedDates.add(datePart);
+                        this.logger.log(`[MAINT] Patched AgentEvent ${e.id} ${e.eventType} agent=${agentId} ${e.durationS ?? 'null'}s → ${computed}s`);
+                        await new Promise((r) => setTimeout(r, 80));
+                    } catch (err) {
+                        this.logger.warn(`[MAINT] Patch failed for ${e.id}: ${err}`);
+                        skipped++;
+                    }
+                } else {
+                    skipped++;
+                }
+            }
+        }
+
+        // Re-run rollup for each affected date so AgentSession numbers update.
+        const dates = Array.from(affectedDates);
+        for (const d of dates) {
+            try {
+                await this.history.rollupSessions(d);
+                this.logger.log(`[MAINT] Rollup re-run for ${d}`);
+            } catch (err) {
+                this.logger.warn(`[MAINT] Rollup failed for ${d}: ${err}`);
+            }
+        }
+
+        this.logger.log(`[MAINT] Backfill AgentEvent durations complete: scanned=${events.length} patched=${patched} skipped=${skipped} dates=${dates.join(',')}`);
+        return { status: 'ok', scanned: events.length, patched, skipped, dates };
+    }
+
+    private todayIst(): string {
+        const ist = new Date(Date.now() + 5.5 * 60 * 60 * 1000);
+        return ist.toISOString().slice(0, 10);
+    }
+
+    private async fetchAgentEventsForBackfill(date: string): Promise<Array<{ id: string; eventType: AgentEventType; eventAt: string; durationS: number | null; agentId: string }>> {
+        const events: Array<{ id: string; eventType: AgentEventType; eventAt: string; durationS: number | null; agentId: string }> = [];
+        let after: string | null = null;
+        const rangeFilter = date === 'all'
+            ? ''
+            : `, filter: { eventAt: { gte: "${date}T00:00:00+05:30", lte: "${date}T23:59:59+05:30" } }`;
+
+        for (let page = 0; page < 50; page++) {
+            const cursorArg: string = after ? `, after: "${after}"` : '';
+            const data: any = await this.platform.query<any>(
+                `{ agentEvents(first: 200${cursorArg}${rangeFilter}, orderBy: [{ eventAt: AscNullsLast }]) {
+                    edges { node { id eventType eventAt durationS agentId } }
+                    pageInfo { hasNextPage endCursor }
+                } }`,
+            );
+            const edges = data?.agentEvents?.edges ?? [];
+            for (const e of edges) events.push(e.node);
+            const pageInfo: { hasNextPage?: boolean; endCursor?: string } = data?.agentEvents?.pageInfo ?? {};
+            if (!pageInfo.hasNextPage) break;
+            after = pageInfo.endCursor ?? null;
+        }
+        return events;
+    }
 }