diff --git a/src/cli/specs/orchestration.ts b/src/cli/specs/orchestration.ts
index 3f63ff3a47d..7ff110aacef 100644
--- a/src/cli/specs/orchestration.ts
+++ b/src/cli/specs/orchestration.ts
@@ -109,11 +109,9 @@ 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.',
+      '--types is the wake condition for --wait; a returned Delivery is always the whole FIFO batch, so it is never filtered by type. Without --wait it has no effect on consuming checks. Only --peek and --all filter their rows.',
       '--format renders the returned rows as local text only; it never writes to another terminal.',
-      'A bound Run replays the same Delivery until --ack or all its messages are retired; process every message before acknowledging.'
+      'A bound Run replays the same Delivery until --ack or all its messages are marked read, even with --types; process every message before acknowledging.'
     ]
   },
   {
diff --git a/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-02.spec.ts b/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-02.spec.ts
index 9291c30c1a2..fb5396bf37c 100644
--- a/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-02.spec.ts
+++ b/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-02.spec.ts
@@ -94,7 +94,7 @@ describe('OrcaRuntimeService', () => {
       runtime.onPtyData('pty-1', '\x1b]0;Codex done\x07', 101)
       expect(write).toHaveBeenCalledWith(
         'pty-1',
-        '\nYou have 1 orchestration message. Run `orca-dev orchestration check --run run_mailbox`.\n'
+        '\n[Orca orchestration notification] You have 1 orchestration message. Run `orca-dev orchestration check --run run_mailbox`.\n'
       )
       expect(write).not.toHaveBeenCalledWith(
         'pty-1',
@@ -472,7 +472,7 @@ describe('OrcaRuntimeService', () => {
     await vi.waitFor(() => {
       expect(write).toHaveBeenCalledWith(
         'pty-1',
-        '\nYou have 1 orchestration message. Run `orca-dev orchestration check --run run_codex_native_title`.\n'
+        '\n[Orca orchestration notification] You have 1 orchestration message. Run `orca-dev orchestration check --run run_codex_native_title`.\n'
       )
     })
     db.close()
diff --git a/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-03.spec.ts b/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-03.spec.ts
index 48cd70703e0..ec36fb9fc8b 100644
--- a/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-03.spec.ts
+++ b/src/main/runtime/orca-runtime-tests/mobile-creation-and-orchestration-part-03.spec.ts
@@ -62,7 +62,7 @@ describe('OrcaRuntimeService', () => {
         .map(([, data]) => data)
         .filter((data): data is string => typeof data === 'string')
       expect(payloads).toContain(
-        '\nYou have 1 orchestration message. Run `orca-dev orchestration check --run run_test`.\n'
+        '\n[Orca orchestration notification] You have 1 orchestration message. Run `orca-dev orchestration check --run run_test`.\n'
       )
       expect(payloads.some((data) => data.includes('reserved completion'))).toBe(false)
       expect(status.delivered_at).toEqual(expect.any(String))
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 8a5968c36f2..8ff0602d1eb 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, isGeneratedId } from '../generated-id'
+import { generateId } from '../generated-id'
 import type { OrchestrationDb } from '../orchestration-db'
 import { exposeDeliveryTimestamps, exposeMessageListTimestamps } from '../utc-timestamp'
 import { ORCHESTRATION_DELIVERY_BATCH_LIMIT } from './mailbox-routing-page'
@@ -43,7 +43,9 @@ export function getOrCreateMailboxDelivery(
     if (params.requireCurrentRunConsumer) {
       this.requireCurrentConsumer(params.runId, params.consumerGeneration)
     }
-    const existing = this.getOutstandingMailboxDelivery(params.mailboxHandle)
+    const existing = this.db
+      .prepare("SELECT * FROM deliveries WHERE mailbox_handle = ? AND status = 'outstanding'")
+      .get(params.mailboxHandle) as DeliveryRow | undefined
     if (existing) {
       if (existing.consumer_generation !== params.consumerGeneration) {
         throw new OrchestrationError(
@@ -51,12 +53,11 @@ export function getOrCreateMailboxDelivery(
           'This mailbox Delivery belongs to a fenced consumer generation.'
         )
       }
-      const messages = this.getDeliveryMessages(existing)
-      if (messages.some((message) => message.read === 0)) {
+      if (!this.retireReadMailboxDelivery(params.mailboxHandle)) {
+        const messages = this.getDeliveryMessages(existing)
         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(',')
@@ -125,20 +126,6 @@ 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 ||
@@ -147,7 +134,7 @@ export function acknowledgeMailboxDelivery(
     ) {
       throw new OrchestrationError(
         'stale_delivery',
-        `Delivery ${params.deliveryId} does not belong to this mailbox.`
+        `Delivery ${params.deliveryId} does not belong to this mailbox. --ack requires a delivery_* ID returned by orchestration check; process the entire batch before acknowledging.`
       )
     }
     if (
@@ -189,19 +176,9 @@ 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
+export function retireReadMailboxDelivery(this: OrchestrationDb, mailboxHandle: string): boolean {
+  const result = this.db
     .prepare(
       `UPDATE deliveries SET status = 'acknowledged', acknowledged_at = datetime('now')
      WHERE mailbox_handle = ? AND status = 'outstanding'
@@ -211,13 +188,20 @@ export function retireReadMailboxDelivery(this: OrchestrationDb, mailboxHandle:
        )`
     )
     .run(mailboxHandle)
+  return result.changes > 0
 }
 
 export function hasOutstandingMailboxDelivery(
   this: OrchestrationDb,
   mailboxHandle: string
 ): boolean {
-  return this.getOutstandingMailboxDelivery(mailboxHandle) !== undefined
+  return Boolean(
+    this.db
+      .prepare(
+        "SELECT 1 FROM deliveries WHERE mailbox_handle = ? AND status = 'outstanding' LIMIT 1"
+      )
+      .get(mailboxHandle)
+  )
 }
 
 export function fenceOutstandingMailboxDelivery(
@@ -232,7 +216,6 @@ export function fenceOutstandingMailboxDelivery(
 }
 
 export type RoleMailboxDeliveryMethods = {
-  getOutstandingMailboxDelivery: typeof getOutstandingMailboxDelivery
   retireReadMailboxDelivery: typeof retireReadMailboxDelivery
   getDeliveryRaw: typeof getDeliveryRaw
   getDeliveryMessages: typeof getDeliveryMessages
@@ -244,7 +227,6 @@ export type RoleMailboxDeliveryMethods = {
 
 export function attachRoleMailboxDelivery(ctor: { prototype: object }): void {
   Object.assign(ctor.prototype, {
-    getOutstandingMailboxDelivery,
     retireReadMailboxDelivery,
     getDeliveryRaw,
     getDeliveryMessages,
diff --git a/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts b/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts
index 820f69d147c..c97a94f3a7f 100644
--- a/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts
+++ b/src/main/runtime/orchestration/orchestration-retired-delivery.test.ts
@@ -86,33 +86,29 @@ describe('retired mailbox deliveries', () => {
     expect(db.getDeliveryRaw(first.delivery.id)?.status).toBe('outstanding')
   })
 
-  it('names the owning delivery when ack receives a message ID without consuming mail', () => {
+  it('explains the delivery ID contract for invalid acknowledgements 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}.`
+      '--ack requires a delivery_* ID returned by orchestration check; process the entire batch before acknowledging.'
     )
     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')
+  it('checks the consumer generation before repairing an already read delivery', () => {
+    const { run, params, insert } = setup()
+    const message = insert('old')
     const first = db.getOrCreateRunDelivery(params)!
+    db.db.prepare('UPDATE messages SET read = 1 WHERE id = ?').run(message.id)
     expect(() =>
-      db.acknowledgeRunDelivery({
-        runId: foreign.id,
-        consumerGeneration: foreign.consumer_generation,
-        deliveryId: message.id
+      db.getOrCreateMailboxDelivery({
+        ...params,
+        mailboxHandle: `run:${run.id}`,
+        consumerGeneration: params.consumerGeneration + 1
       })
-    ).toThrow('Run orchestration check to obtain the Delivery id.')
+    ).toThrow(expect.objectContaining({ code: 'consumer_fenced' }))
     expect(db.getDeliveryRaw(first.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
index 59a0718b66a..e3713bd31a2 100644
--- 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
@@ -5,7 +5,7 @@ describe('Run delivery history', () => {
   const h = createOrchestrationRpcHarness()
   afterEach(() => h.cleanup())
 
-  it('exposes the outstanding delivery without minting or acknowledging it', async () => {
+  it('does not label filtered history as an acknowledgeable delivery', async () => {
     const { db, ctx, activeRunId } = h.setup()
     const params = { terminal: 'term_coord', run: activeRunId, all: true }
     db.insertMessage({
@@ -15,7 +15,6 @@ describe('Run delivery history', () => {
       subject: 'waiting'
     })
     expect(await h.call('orchestration.check', params, ctx)).toMatchObject({
-      deliveryId: null,
       count: 1
     })
     expect(db.hasOutstandingRunDelivery(activeRunId!)).toBe(false)
@@ -23,10 +22,24 @@ describe('Run delivery history', () => {
       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
+    db.insertMessage({
+      from: 'worker',
+      to: `run:${activeRunId}`,
+      runId: activeRunId,
+      subject: 'later completion',
+      type: 'worker_done'
     })
+    const history = await h.call(
+      'orchestration.check',
+      {
+        ...params,
+        format: true,
+        types: 'worker_done'
+      },
+      ctx
+    )
+    expect(history).toMatchObject({ count: 1, messages: [{ subject: 'later completion' }] })
+    expect(history).not.toHaveProperty('deliveryId')
     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 598c080623a..6db89cf4a20 100644
--- a/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts
+++ b/src/main/runtime/rpc/methods/orchestration/messaging/check-run.ts
@@ -101,7 +101,6 @@ 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) {