diff --git a/packages/server/src/server/agent/agent-manager.ts b/packages/server/src/server/agent/agent-manager.ts
index 0ac7e7d25c..c8a6b89c55 100644
--- a/packages/server/src/server/agent/agent-manager.ts
+++ b/packages/server/src/server/agent/agent-manager.ts
@@ -85,6 +85,7 @@ import {
   AgentTimeline,
   type TimelineAppendResult,
   type TimelineCommit,
+  type TimelineHead,
   type TimelineEntry,
   type TimelineIngestResult,
   type TimelineRetirementCommit,
@@ -1449,20 +1450,10 @@ export class AgentManager {
     return await this.timeline.readRows({ agentId: id });
   }
 
-  /**
-   * The timeline head of a loaded agent, or null when this agent is not loaded. Never loads.
-   * `seq` is the last committed sequence number, a retirement's included.
-   */
-  async getLoadedTimelineHead(
-    id: string,
-  ): Promise<{ epoch: string; seq: number; retirementCount: number } | null> {
+  /** The timeline head of a loaded agent, or null when this agent is not loaded. Never loads. */
+  async getLoadedTimelineHead(id: string): Promise<TimelineHead | null> {
     if (!this.getAgent(id)) return null;
-    const page = await this.timeline.fetch({ agentId: id }, { direction: "tail", limit: 0 });
-    return {
-      epoch: page.epoch,
-      seq: page.window.nextSeq - 1,
-      retirementCount: page.retirementCount,
-    };
+    return await this.timeline.describe({ agentId: id });
   }
 
   async fetchTimeline(
diff --git a/packages/server/src/server/agent/timeline/agent-timeline.test.ts b/packages/server/src/server/agent/timeline/agent-timeline.test.ts
index a846e22731..c43b9491f4 100644
--- a/packages/server/src/server/agent/timeline/agent-timeline.test.ts
+++ b/packages/server/src/server/agent/timeline/agent-timeline.test.ts
@@ -208,6 +208,7 @@ describe.each(
     expect(await timeline.describe(child)).toBeNull();
     expect(await timeline.describe(root("a"))).toEqual({
       epoch: "parent",
+      seq: 1,
       size: 1,
       retirementCount: 0,
       rewind: null,
@@ -765,6 +766,7 @@ describe.each(TIMELINE_CONTRACT_BACKENDS)(
       expect(texts(backend.retiredRows(scope))).toEqual(["b", "tool_call", "B"]);
       expect(await timeline.describe(scope)).toEqual({
         epoch: "e",
+        seq: 8,
         size: 4,
         retirementCount: 1,
         rewind: null,
diff --git a/packages/server/src/server/agent/timeline/internal/backend.ts b/packages/server/src/server/agent/timeline/internal/backend.ts
index 098897ef36..d47062fcb5 100644
--- a/packages/server/src/server/agent/timeline/internal/backend.ts
+++ b/packages/server/src/server/agent/timeline/internal/backend.ts
@@ -32,6 +32,8 @@ export interface TimelineSeed {
 
 export interface TimelineHead {
   epoch: string;
+  /** The last sequence number committed, a retirement's included; 0 before any commit. */
+  seq: number;
   /** Projected (displayed) row count. */
   size: number;
   /** Rewinds applied since the history was created. */
diff --git a/packages/server/src/server/agent/timeline/internal/memory-backend.ts b/packages/server/src/server/agent/timeline/internal/memory-backend.ts
index 7117a8d863..53894fb211 100644
--- a/packages/server/src/server/agent/timeline/internal/memory-backend.ts
+++ b/packages/server/src/server/agent/timeline/internal/memory-backend.ts
@@ -283,6 +283,7 @@ export class MemoryTimelineBackend implements AgentTimelineBackend {
   private describe(state: MemoryTimelineState): TimelineHead {
     return {
       epoch: state.epoch,
+      seq: state.nextSeq - 1,
       size: state.projection.size,
       retirementCount: state.retirementCount,
       rewind: state.rewind ? { ...state.rewind } : null,