diff --git a/src/cli/specs/orchestration.ts b/src/cli/specs/orchestration.ts
index e62911b2c76..3f63ff3a47d 100644
--- a/src/cli/specs/orchestration.ts
+++ b/src/cli/specs/orchestration.ts
@@ -110,8 +110,10 @@ export const ORCHESTRATION_COMMAND_SPECS: CommandSpec[] = [
     notes: [
       'On Windows PowerShell, quote comma-separated type filters, e.g. --types "worker_done,escalation".',
       '--types is the wake condition for --wait; a returned Delivery is always the whole FIFO batch, so it is never filtered by type. Only --peek and --all filter their rows.',
+      'Without --wait, --types does not filter a consuming check. An outstanding Delivery replays before the wake condition is tested.',
+      '--all shows the outstanding deliveryId for recovery; its history rows are not necessarily that batch. Check the full Delivery before --ack.',
       '--format renders the returned rows as local text only; it never writes to another terminal.',
-      'A bound Run replays the same Delivery until --ack; process every message before acknowledging.'
+      'A bound Run replays the same Delivery until --ack or all its messages are retired; process every message before acknowledging.'
     ]
   },
   {
diff --git a/src/main/runtime/orchestration/db/messages/message-inbox.ts b/src/main/runtime/orchestration/db/messages/message-inbox.ts
index e9b800d431e..1ef57776b00 100644
--- a/src/main/runtime/orchestration/db/messages/message-inbox.ts
+++ b/src/main/runtime/orchestration/db/messages/message-inbox.ts
@@ -9,7 +9,8 @@ const MESSAGE_MUTATION_SAVEPOINT = 'message_id_mutation'
 function runBatchedMessageMutation(
   db: OrchestrationDb,
   ids: string[],
-  sqlForPlaceholders: (placeholders: string) => string
+  sqlForPlaceholders: (placeholders: string) => string,
+  retireReadDeliveries = false
 ): void {
   if (ids.length === 0) {
     return
@@ -20,6 +21,14 @@ function runBatchedMessageMutation(
       const batch = ids.slice(offset, offset + MESSAGE_ID_UPDATE_BATCH_SIZE)
       const placeholders = batch.map(() => '?').join(',')
       db.db.prepare(sqlForPlaceholders(placeholders)).run(...batch)
+      if (retireReadDeliveries) {
+        const mailboxes = db.db
+          .prepare(`SELECT DISTINCT to_handle FROM messages WHERE id IN (${placeholders})`)
+          .all(...batch) as { to_handle: string }[]
+        for (const mailbox of mailboxes) {
+          db.retireReadMailboxDelivery(mailbox.to_handle)
+        }
+      }
     }
     db.db.exec(`RELEASE ${MESSAGE_MUTATION_SAVEPOINT}`)
   } catch (error) {
@@ -160,7 +169,8 @@ export function markAsRead(this: OrchestrationDb, ids: string[]): void {
       `UPDATE messages
        SET read = 1, pointer_enter_pending = 0, pointer_pty_id = NULL,
            pointer_process_incarnation = NULL
-       WHERE id IN (${placeholders})`
+       WHERE id IN (${placeholders})`,
+    true
   )
 }
 
@@ -216,7 +226,8 @@ export function markAsReadAndDelivered(this: OrchestrationDb, ids: string[]): vo
        SET read = 1, delivered_at = COALESCE(delivered_at, datetime('now')),
            pointer_enter_pending = 0, pointer_pty_id = NULL,
            pointer_process_incarnation = NULL
-       WHERE id IN (${placeholders})`
+       WHERE id IN (${placeholders})`,
+    true
   )
 }
 
diff --git a/src/main/runtime/orchestration/db/messages/role-mailbox-delivery.ts b/src/main/runtime/orchestration/db/messages/role-mailbox-delivery.ts
index c7553c089b7..8a5968c36f2 100644
--- a/src/main/runtime/orchestration/db/messages/role-mailbox-delivery.ts
+++ b/src/main/runtime/orchestration/db/messages/role-mailbox-delivery.ts
@@ -1,6 +1,6 @@
 import type { DeliveryRow, MessageRow, MessageType } from '../../types'
 import { OrchestrationError } from '../../orchestration-error'
-import { generateId } from '../generated-id'
+import { generateId, isGeneratedId } from '../generated-id'
 import type { OrchestrationDb } from '../orchestration-db'
 import { exposeDeliveryTimestamps, exposeMessageListTimestamps } from '../utc-timestamp'
 import { ORCHESTRATION_DELIVERY_BATCH_LIMIT } from './mailbox-routing-page'
@@ -43,9 +43,7 @@ export function getOrCreateMailboxDelivery(
     if (params.requireCurrentRunConsumer) {
       this.requireCurrentConsumer(params.runId, params.consumerGeneration)
     }
-    const existing = this.db
-      .prepare("SELECT * FROM deliveries WHERE mailbox_handle = ? AND status = 'outstanding'")
-      .get(params.mailboxHandle) as DeliveryRow | undefined
+    const existing = this.getOutstandingMailboxDelivery(params.mailboxHandle)
     if (existing) {
       if (existing.consumer_generation !== params.consumerGeneration) {
         throw new OrchestrationError(
@@ -54,8 +52,11 @@ export function getOrCreateMailboxDelivery(
         )
       }
       const messages = this.getDeliveryMessages(existing)
-      this.db.exec('COMMIT')
-      return { delivery: exposeDeliveryTimestamps(existing), messages, replayed: true }
+      if (messages.some((message) => message.read === 0)) {
+        this.db.exec('COMMIT')
+        return { delivery: exposeDeliveryTimestamps(existing), messages, replayed: true }
+      }
+      this.retireReadMailboxDelivery(params.mailboxHandle)
     }
     if (params.wakeTypes?.length) {
       const placeholders = params.wakeTypes.map(() => '?').join(',')
@@ -124,6 +125,20 @@ export function acknowledgeMailboxDelivery(
     if (params.requireCurrentRunConsumer) {
       this.requireCurrentConsumer(params.runId, params.consumerGeneration)
     }
+    if (isGeneratedId(params.deliveryId, 'msg')) {
+      const outstanding = this.getOutstandingMailboxDelivery(params.mailboxHandle)
+      const containsMessage =
+        outstanding &&
+        outstanding.run_id === params.runId &&
+        (JSON.parse(outstanding.message_ids) as string[]).includes(params.deliveryId)
+      const guidance = containsMessage
+        ? `Process the entire batch, then use --ack ${outstanding.id}.`
+        : 'Run orchestration check to obtain the Delivery id.'
+      throw new OrchestrationError(
+        'stale_delivery',
+        `--ack takes a Delivery id, not message id ${params.deliveryId}. ${guidance}`
+      )
+    }
     const delivery = this.getDeliveryRaw(params.deliveryId)
     if (
       !delivery ||
@@ -174,17 +189,35 @@ export function acknowledgeMailboxDelivery(
   }
 }
 
+export function getOutstandingMailboxDelivery(
+  this: OrchestrationDb,
+  mailboxHandle: string
+): DeliveryRow | undefined {
+  const row = this.db
+    .prepare("SELECT * FROM deliveries WHERE mailbox_handle = ? AND status = 'outstanding'")
+    .get(mailboxHandle) as DeliveryRow | undefined
+  return row ? exposeDeliveryTimestamps(row) : undefined
+}
+
+// Acknowledgment keeps late consumer acks idempotent after lifecycle suppression.
+export function retireReadMailboxDelivery(this: OrchestrationDb, mailboxHandle: string): void {
+  this.db
+    .prepare(
+      `UPDATE deliveries SET status = 'acknowledged', acknowledged_at = datetime('now')
+     WHERE mailbox_handle = ? AND status = 'outstanding'
+       AND NOT EXISTS (
+         SELECT 1 FROM json_each(deliveries.message_ids) AS member
+         JOIN messages ON messages.id = member.value WHERE messages.read = 0
+       )`
+    )
+    .run(mailboxHandle)
+}
+
 export function hasOutstandingMailboxDelivery(
   this: OrchestrationDb,
   mailboxHandle: string
 ): boolean {
-  return Boolean(
-    this.db
-      .prepare(
-        "SELECT 1 FROM deliveries WHERE mailbox_handle = ? AND status = 'outstanding' LIMIT 1"
-      )
-      .get(mailboxHandle)
-  )
+  return this.getOutstandingMailboxDelivery(mailboxHandle) !== undefined
 }
 
 export function fenceOutstandingMailboxDelivery(
@@ -199,6 +232,8 @@ export function fenceOutstandingMailboxDelivery(
 }
 
 export type RoleMailboxDeliveryMethods = {
+  getOutstandingMailboxDelivery: typeof getOutstandingMailboxDelivery
+  retireReadMailboxDelivery: typeof retireReadMailboxDelivery
   getDeliveryRaw: typeof getDeliveryRaw
   getDeliveryMessages: typeof getDeliveryMessages
   getOrCreateMailboxDelivery: typeof getOrCreateMailboxDelivery
@@ -209,6 +244,8 @@ export type RoleMailboxDeliveryMethods = {
 
 export function attachRoleMailboxDelivery(ctor: { prototype: object }): void {
   Object.assign(ctor.prototype, {
+    getOutstandingMailboxDelivery,
+    retireReadMailboxDelivery,
     getDeliveryRaw,
     getDeliveryMessages,
     getOrCreateMailboxDelivery,
diff --git a/src/main/runtime/orchestration/formatter.test.ts b/src/main/runtime/orchestration/formatter.test.ts
index 148bfad9b73..e42b80f3f46 100644
--- a/src/main/runtime/orchestration/formatter.test.ts
+++ b/src/main/runtime/orchestration/formatter.test.ts
@@ -187,7 +187,7 @@ describe('formatMessagesForInjection', () => {
 describe('formatMessagePointer', () => {
   it('formats a singular pointer without message content', () => {
     expect(formatMessagePointer(1, 'run:run_1')).toBe(
-      '\nYou have 1 orchestration message. Run `orca orchestration check --run run_1`.\n'
+      '\n[Orca orchestration notification] You have 1 orchestration message. Run `orca orchestration check --run run_1`.\n'
     )
   })
 
diff --git a/src/main/runtime/orchestration/formatter.ts b/src/main/runtime/orchestration/formatter.ts
index 2dd4f86777b..540e1def1ba 100644
--- a/src/main/runtime/orchestration/formatter.ts
+++ b/src/main/runtime/orchestration/formatter.ts
@@ -118,5 +118,5 @@ export function formatMessagePointer(
   const runFlag = mailboxHandle?.startsWith('run:')
     ? ` --run ${mailboxHandle.slice('run:'.length)}`
     : ''
-  return `\nYou have ${count} orchestration ${noun}. Run \`${cliCommand} orchestration check${runFlag}\`.\n`
+  return `\n[Orca orchestration notification] You have ${count} orchestration ${noun}. Run \`${cliCommand} orchestration check${runFlag}\`.\n`
 }
diff --git a/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts b/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts
new file mode 100644
index 00000000000..820f69d147c
--- /dev/null
+++ b/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts
@@ -0,0 +1,142 @@
+import { afterEach, describe, expect, it } from 'vitest'
+import { OrchestrationDb } from './db'
+import { createRootDispatch } from './db/root-dispatch-test-fixture'
+import { reconcileLifecycleMessage } from './lifecycle-reconciliation'
+
+describe('retired mailbox deliveries', () => {
+  let db: OrchestrationDb
+  afterEach(() => db?.close())
+
+  function setup() {
+    db = new OrchestrationDb(':memory:')
+    const run = db.createRun({
+      objective: 'Retired delivery',
+      coordinatorHandle: 'term_coord',
+      coordinatorPaneKey: 'tab:11111111-1111-4111-8111-111111111111'
+    })
+    const params = { runId: run.id, consumerGeneration: run.consumer_generation }
+    const insert = (subject: string) =>
+      db.insertMessage({ runId: run.id, from: 'worker', to: `run:${run.id}`, subject })
+    return { run, params, insert }
+  }
+
+  it('retires the heartbeat delivery atomically when completion suppresses its contents', () => {
+    const { run, params } = setup()
+    const task = db.createTask({ runId: run.id, spec: 'work' })
+    const dispatch = createRootDispatch(db, task.id, 'worker')
+    const insert = (type: 'heartbeat' | 'worker_done') =>
+      db.insertMessage({
+        runId: run.id,
+        from: 'worker',
+        to: `run:${run.id}`,
+        subject: type,
+        type,
+        payload: JSON.stringify({ taskId: task.id, dispatchId: dispatch.id, outcome: 'succeeded' })
+      })
+    insert('heartbeat')
+    const first = db.getOrCreateRunDelivery(params)!
+    const done = insert('worker_done')
+    expect(reconcileLifecycleMessage(db, done).action).toBe('completed')
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('acknowledged')
+    expect(db.hasOutstandingRunDelivery(run.id)).toBe(false)
+    expect(
+      db
+        .getOrCreateRunDelivery({ ...params, wakeTypes: ['worker_done'] })
+        ?.messages.map((m) => m.id)
+    ).toEqual([done.id])
+    expect(db.acknowledgeRunDelivery({ ...params, deliveryId: first.delivery.id }).duplicate).toBe(
+      true
+    )
+  })
+
+  it('repairs an already fully-read outstanding delivery before replay', () => {
+    const { params, insert } = setup()
+    const old = insert('old')
+    const first = db.getOrCreateRunDelivery(params)!
+    db.db.prepare('UPDATE messages SET read = 1 WHERE id = ?').run(old.id)
+    const next = insert('next')
+    const current = db.getOrCreateRunDelivery(params)!
+    expect(current.messages.map((m) => m.id)).toEqual([next.id])
+    expect(current.replayed).toBe(false)
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('acknowledged')
+  })
+
+  it('preserves the entire replay batch while any member is unread', () => {
+    const { params, insert } = setup()
+    const a = insert('a')
+    const b = insert('b')
+    const first = db.getOrCreateRunDelivery(params)!
+    db.markAsReadAndDelivered([a.id])
+    insert('later')
+    const replay = db.getOrCreateRunDelivery(params)!
+    expect(replay.delivery.id).toBe(first.delivery.id)
+    expect(replay.messages.map((m) => m.id)).toEqual([a.id, b.id])
+    expect(replay.replayed).toBe(true)
+  })
+
+  it('rolls retirement back with the enclosing lifecycle transaction', () => {
+    const { params, insert } = setup()
+    const message = insert('old')
+    const first = db.getOrCreateRunDelivery(params)!
+    db.db.exec('BEGIN')
+    db.markAsReadAndDelivered([message.id])
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('acknowledged')
+    db.db.exec('ROLLBACK')
+    expect(db.getMessageById(message.id)?.read).toBe(0)
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('outstanding')
+  })
+
+  it('names the owning delivery when ack receives a message ID without consuming mail', () => {
+    const { params, insert } = setup()
+    const message = insert('pending')
+    const first = db.getOrCreateRunDelivery(params)!
+    expect(() => db.acknowledgeRunDelivery({ ...params, deliveryId: message.id })).toThrow(
+      `Process the entire batch, then use --ack ${first.delivery.id}.`
+    )
+    expect(db.getMessageById(message.id)?.read).toBe(0)
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('outstanding')
+  })
+
+  it('does not reveal a delivery from another mailbox in a wrong-ID error', () => {
+    const { params, insert } = setup()
+    const foreign = db.createRun({
+      objective: 'other',
+      coordinatorHandle: 'other',
+      coordinatorPaneKey: 'other:22222222-2222-4222-9222-222222222222'
+    })
+    const message = insert('private')
+    const first = db.getOrCreateRunDelivery(params)!
+    expect(() =>
+      db.acknowledgeRunDelivery({
+        runId: foreign.id,
+        consumerGeneration: foreign.consumer_generation,
+        deliveryId: message.id
+      })
+    ).toThrow('Run orchestration check to obtain the Delivery id.')
+    expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('outstanding')
+  })
+
+  it.each(['markAsRead', 'markAsReadAndDelivered'] as const)(
+    '%s retires dispatch mail without retiring a different mailbox',
+    (method) => {
+      const { run, params, insert } = setup()
+      insert('coordinator mail')
+      const coordinator = db.getOrCreateRunDelivery(params)!
+      const task = db.createTask({ runId: run.id, spec: 'worker mail' })
+      const dispatch = createRootDispatch(db, task.id, 'worker')
+      const mailboxHandle = `dispatch:${dispatch.id}`
+      const message = db.insertMessage({
+        runId: run.id,
+        from: 'term_coord',
+        to: mailboxHandle,
+        subject: 'worker mail'
+      })
+      const workerParams = { ...params, mailboxHandle }
+      const worker = db.getOrCreateMailboxDelivery(workerParams)!
+      db[method]([message.id])
+      expect(db.getDeliveryRaw(worker.delivery.id)?.status).toBe('acknowledged')
+      expect(db.getOrCreateMailboxDelivery(workerParams)).toBeUndefined()
+      expect(db.getDeliveryRaw(coordinator.delivery.id)?.status).toBe('outstanding')
+    }
+  )
+})
diff --git a/src/main/runtime/rpc/methods/orchestration/messaging/check-delivery-history.test.ts b/src/main/runtime/rpc/methods/orchestration/messaging/check-delivery-history.test.ts
new file mode 100644
index 00000000000..59a0718b66a
--- /dev/null
+++ b/src/main/runtime/rpc/methods/orchestration/messaging/check-delivery-history.test.ts
@@ -0,0 +1,33 @@
+import { afterEach, describe, expect, it } from 'vitest'
+import { createOrchestrationRpcHarness } from '../rpc-test-harness'
+
+describe('Run delivery history', () => {
+  const h = createOrchestrationRpcHarness()
+  afterEach(() => h.cleanup())
+
+  it('exposes the outstanding delivery without minting or acknowledging it', async () => {
+    const { db, ctx, activeRunId } = h.setup()
+    const params = { terminal: 'term_coord', run: activeRunId, all: true }
+    db.insertMessage({
+      from: 'worker',
+      to: `run:${activeRunId}`,
+      runId: activeRunId,
+      subject: 'waiting'
+    })
+    expect(await h.call('orchestration.check', params, ctx)).toMatchObject({
+      deliveryId: null,
+      count: 1
+    })
+    expect(db.hasOutstandingRunDelivery(activeRunId!)).toBe(false)
+    const delivery = db.getOrCreateRunDelivery({
+      runId: activeRunId!,
+      consumerGeneration: db.getRun(activeRunId!)!.consumer_generation
+    })!
+    expect(await h.call('orchestration.check', { ...params, format: true }, ctx)).toMatchObject({
+      deliveryId: delivery.delivery.id,
+      count: 1
+    })
+    expect(db.getDeliveryRaw(delivery.delivery.id)?.status).toBe('outstanding')
+    expect(db.getMessageById(delivery.messages[0].id)?.read).toBe(0)
+  })
+})
diff --git a/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts b/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts
index 6db89cf4a20..598c080623a 100644
--- a/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts
+++ b/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts
@@ -101,6 +101,7 @@ export async function checkRunMailbox(args: {
     const result = {
       messages: exposeMessages(messages),
       count: messages.length,
+      deliveryId: db.getOutstandingMailboxDelivery(address)?.id ?? null,
       acknowledged: acknowledged?.delivery.id ?? null
     }
     if (params.format || params.inject) {
diff --git a/src/shared/orchestration-check-output.test.ts b/src/shared/orchestration-check-output.test.ts
index 00ffbb79da3..df3248bd2fd 100644
--- a/src/shared/orchestration-check-output.test.ts
+++ b/src/shared/orchestration-check-output.test.ts
@@ -1,5 +1,8 @@
 import { describe, expect, it } from 'vitest'
-import { prepareOrchestrationCheckOutput } from './orchestration-check-output'
+import {
+  formatOrchestrationCheckText,
+  prepareOrchestrationCheckOutput
+} from './orchestration-check-output'
 
 describe('prepareOrchestrationCheckOutput', () => {
   it('keeps mixed read-only mail safe and current Run replies executable', () => {
@@ -40,3 +43,19 @@ describe('prepareOrchestrationCheckOutput', () => {
     expect(prepared.formatted).not.toContain('unsafe stale formatter output')
   })
 })
+
+describe('formatted delivery acknowledgment', () => {
+  it('retains the delivery ID above formatted message bodies', () => {
+    expect(
+      formatOrchestrationCheckText(
+        {
+          messages: [{ id: 'msg_one', from_handle: 'worker' }],
+          count: 1,
+          deliveryId: 'delivery_one',
+          formatted: 'Message body'
+        },
+        'term_coord'
+      )
+    ).toBe('Delivery delivery_one\nMessage body')
+  })
+})
diff --git a/src/shared/orchestration-check-output.ts b/src/shared/orchestration-check-output.ts
index e736b92f4dd..5429c542341 100644
--- a/src/shared/orchestration-check-output.ts
+++ b/src/shared/orchestration-check-output.ts
@@ -81,7 +81,7 @@ export function formatOrchestrationCheckText(
     : ''
   const deliveryNotice = formatCurrentDeliveryNotice(prepared.legacyCompatibility?.currentDelivery)
   if (prepared.formatted) {
-    return `${legacyHeader}${prepared.formatted}${deliveryNotice}`
+    return `${legacyHeader}${prepared.deliveryId ? `Delivery ${prepared.deliveryId}\n` : ''}${prepared.formatted}${deliveryNotice}`
   }
   if (prepared.count === 0) {
     if (prepared.timedOut) {