diff --git a/src/main/claude/claude-structured-session-acquisition.ts b/src/main/claude/claude-structured-session-acquisition.ts
index 8b23c9a8d70..3da84c21129 100644
--- a/src/main/claude/claude-structured-session-acquisition.ts
+++ b/src/main/claude/claude-structured-session-acquisition.ts
@@ -143,6 +143,7 @@ export async function acquireClaudeSession({
       )
     }
     acquisitions.assertCurrent(sessionId, attempt)
+    const priorSession = sessions.get(sessionId)
     if (!(await closeClaudePublishedSessionForDeps(sessions, sessionId, deps))) {
       throw new AgentSessionAcquisitionExitUnprovenError(
         new Error(`claude session ${sessionId} could not be stopped`)
@@ -151,8 +152,19 @@ export async function acquireClaudeSession({
     // Any earlier session is closed or already gone: its exit says nothing about this start.
     exits.delete(sessionId)
     acquisitions.assertCurrent(sessionId, attempt)
+    // Closing persists the prior connection's final leaf, so launch validates that durable head.
+    const launchIdentity = priorSession
+      ? {
+          ...input.identity,
+          providerHandle: {
+            kind: 'claude' as const,
+            sessionId: priorSession.providerSessionId,
+            leafUuid: priorSession.leafUuid
+          }
+        }
+      : input.identity
     const launch = await deps
-      .resolveLaunch({ identity: input.identity })
+      .resolveLaunch({ identity: launchIdentity })
       .catch((error: unknown) => {
         throw error instanceof AgentSessionPreSpawnError
           ? error
diff --git a/src/main/runtime/claude-structured-session-integration.test.ts b/src/main/runtime/claude-structured-session-integration.test.ts
index 2a804ed822a..f4366caf5d4 100644
--- a/src/main/runtime/claude-structured-session-integration.test.ts
+++ b/src/main/runtime/claude-structured-session-integration.test.ts
@@ -563,14 +563,27 @@ describe('a structured Claude session over agentSession.*', () => {
     ).resolves.toMatchObject({ turnId: 'user-1', cancelled: true })
     expect(claude.live().calls.at(-1)).toMatchObject({ subtype: 'interrupt' })
 
+    const host = getStructuredAgentSessionHost() as unknown as {
+      deps: {
+        store: {
+          getRecord: (sessionId: string) => {
+            providerHandleChain: { handle: { provider: string; leafUuid?: string | null } }[]
+          }
+        }
+      }
+    }
+    expect(host.deps.store.getRecord(SESSION).providerHandleChain.at(-1)?.handle).toMatchObject({
+      provider: 'claude',
+      leafUuid: null
+    })
     const old = claude.live()
     const resumed = await ok<{ fence: number }>('agentSession.ensure', ensureParams(created.fence))
     expect(resumed.fence).toBe(created.fence + 1)
     expect(old.closed).toBe(true)
-    expect(claude.live().launch.options).toMatchObject({ resume: PROVIDER_SESSION })
-    const host = getStructuredAgentSessionHost() as unknown as {
-      deps: { store: { getRecord: (sessionId: string) => { providerHandleChain: unknown[] } } }
-    }
+    expect(claude.live().launch.options).toMatchObject({
+      resume: PROVIDER_SESSION,
+      resumeSessionAt: 'assistant-leaf'
+    })
     expect(host.deps.store.getRecord(SESSION).providerHandleChain.at(-1)).toMatchObject({
       handle: {
         provider: 'claude',