diff --git a/apps/mobile-rn/__tests__/generation-key-lifecycle-r2-29.test.ts b/apps/mobile-rn/__tests__/generation-key-lifecycle-r2-29.test.ts
new file mode 100644
index 0000000..b23a246
--- /dev/null
+++ b/apps/mobile-rn/__tests__/generation-key-lifecycle-r2-29.test.ts
@@ -0,0 +1,226 @@
+jest.mock('../src/lib/supabase', () => ({
+  supabase: {
+    rpc: jest.fn(),
+    from: jest.fn(),
+    channel: jest.fn(),
+    removeChannel: jest.fn(),
+  },
+}))
+
+import AsyncStorage from '@react-native-async-storage/async-storage'
+import type { MeetingDocument } from '@d3ro/api-client'
+import {
+  generationKeyDisposition,
+  type GenerationAttemptOutcome,
+  type GenerationKeyDisposition,
+} from '../src/features/templates/generation-key-policy'
+import { getOrCreateGenerationIdempotencyKey } from '../src/features/templates/generation-idempotency'
+import {
+  generateMeetingDocumentOnce,
+  generationAttemptOutcome,
+  TemplateServiceError,
+  type GenerateMeetingDocumentOnceDeps,
+} from '../src/features/templates'
+import type { GenerateMeetingDocumentOptions } from '../src/features/templates'
+
+const USER_ID = '11111111-1111-4111-8111-111111111111'
+const MEETING_ID = '33333333-3333-4333-8333-333333333333'
+const TEMPLATE_ID = '44444444-4444-4444-8444-444444444444'
+const DOCUMENT_ID = '55555555-5555-4555-8555-555555555555'
+const ACCESS_TOKEN = 'access-token-with-enough-length'
+
+function response(status: number, errorCode: string | null): GenerationAttemptOutcome {
+  return { kind: 'server-response', status, errorCode }
+}
+
+describe('generationKeyDisposition', () => {
+  const table: Array<[string, GenerationAttemptOutcome, GenerationKeyDisposition]> = [
+    ['success', { kind: 'succeeded' }, 'discard'],
+    ['idempotent 200 replay', response(200, null), 'discard'],
+    ['no response (network loss / abort / local pre-flight)', { kind: 'no-response' }, 'retain'],
+    ['400 idempotency conflict or invalid request', response(400, 'invalid_request'), 'discard'],
+    ['401 session expired before claim', response(401, 'unauthorized'), 'retain'],
+    ['403 forbidden', response(403, 'forbidden'), 'discard'],
+    ['404 not found', response(404, 'not_found'), 'discard'],
+    ['409 generation_failed', response(409, 'generation_failed'), 'discard'],
+    ['409 generation_in_progress', response(409, 'generation_in_progress'), 'retain'],
+    ['409 without body', response(409, null), 'retain'],
+    ['429 quota exceeded', response(429, 'quota_exceeded'), 'discard'],
+    ['500 commit_failed (row marked failed)', response(500, 'commit_failed'), 'discard'],
+    ['500 internal_error (state unknown)', response(500, 'internal_error'), 'retain'],
+    ['502 provider_request_failed', response(502, 'provider_request_failed'), 'discard'],
+    ['502 provider_invalid_response', response(502, 'provider_invalid_response'), 'discard'],
+    ['504 provider_timeout', response(504, 'provider_timeout'), 'discard'],
+    ['504 gateway timeout without function body', response(504, null), 'retain'],
+    ['503 unknown gateway error', response(503, 'service_unavailable'), 'retain'],
+  ]
+
+  it.each(table)('%s -> %s', (_label, outcome, expected) => {
+    expect(generationKeyDisposition(outcome)).toBe(expected)
+  })
+})
+
+describe('generationAttemptOutcome', () => {
+  it('uses the server response carried by the service error', () => {
+    const error = new TemplateServiceError('provider', 'provider_timeout', true, {
+      status: 504,
+      errorCode: 'provider_timeout',
+    })
+    expect(generationAttemptOutcome(error)).toEqual(response(504, 'provider_timeout'))
+  })
+
+  it('treats errors without a server response as no response', () => {
+    expect(generationAttemptOutcome(new TemplateServiceError('network', 'Network request failed', true)))
+      .toEqual({ kind: 'no-response' })
+    expect(generationAttemptOutcome(new TypeError('Network request failed')))
+      .toEqual({ kind: 'no-response' })
+  })
+})
+
+describe('generateMeetingDocumentOnce', () => {
+  const fetchMock = jest.fn()
+  const originalFetch = global.fetch
+
+  function jsonResponse(status: number, body: unknown): Response {
+    return {
+      ok: status >= 200 && status < 300,
+      status,
+      json: async () => body,
+    } as unknown as Response
+  }
+
+  function sentKey(callIndex: number): string {
+    const init = fetchMock.mock.calls[callIndex]?.[1] as { body: string }
+    return (JSON.parse(init.body) as { idempotencyKey: string }).idempotencyKey
+  }
+
+  const document = {
+    id: DOCUMENT_ID,
+    meeting_id: MEETING_ID,
+    template_id: TEMPLATE_ID,
+  } as unknown as MeetingDocument
+
+  const options = {
+    userId: USER_ID,
+    accessToken: ACCESS_TOKEN,
+    meetingId: MEETING_ID,
+    templateId: TEMPLATE_ID,
+    title: 'Weekly sync · Minutes',
+  }
+
+  beforeEach(async () => {
+    await AsyncStorage.clear()
+    fetchMock.mockReset()
+    global.fetch = fetchMock as unknown as typeof fetch
+  })
+
+  afterAll(() => {
+    global.fetch = originalFetch
+  })
+
+  it('starts a fresh operation after the server marks the request failed (provider timeout)', async () => {
+    fetchMock
+      .mockResolvedValueOnce(jsonResponse(504, { error: 'provider_timeout' }))
+      .mockResolvedValueOnce(jsonResponse(200, { document, idempotent: false }))
+
+    await expect(generateMeetingDocumentOnce(options)).rejects.toMatchObject({ code: 'provider' })
+    const generated = await generateMeetingDocumentOnce(options)
+
+    expect(generated.document.id).toBe(DOCUMENT_ID)
+    expect(sentKey(1)).not.toBe(sentKey(0))
+  })
+
+  it('starts a fresh operation after an idempotency hash conflict', async () => {
+    fetchMock
+      .mockResolvedValueOnce(jsonResponse(400, { error: 'invalid_request' }))
+      .mockResolvedValueOnce(jsonResponse(200, { document, idempotent: false }))
+
+    await expect(generateMeetingDocumentOnce(options)).rejects.toMatchObject({ code: 'validation' })
+    await generateMeetingDocumentOnce(options)
+
+    expect(sentKey(1)).not.toBe(sentKey(0))
+  })
+
+  it('reports 409 generation_failed as a retryable server error and discards the key', async () => {
+    fetchMock
+      .mockResolvedValueOnce(jsonResponse(409, { error: 'generation_failed' }))
+      .mockResolvedValueOnce(jsonResponse(200, { document, idempotent: false }))
+
+    await expect(generateMeetingDocumentOnce(options))
+      .rejects.toMatchObject({ code: 'server', retryable: true })
+    await generateMeetingDocumentOnce(options)
+
+    expect(sentKey(1)).not.toBe(sentKey(0))
+  })
+
+  it('reuses the key while the server is still processing it', async () => {
+    fetchMock
+      .mockResolvedValueOnce(jsonResponse(409, { error: 'generation_in_progress' }))
+      .mockResolvedValueOnce(jsonResponse(200, { document, idempotent: true }))
+
+    await expect(generateMeetingDocumentOnce(options)).rejects.toMatchObject({ code: 'in-progress' })
+    await generateMeetingDocumentOnce(options)
+
+    expect(sentKey(1)).toBe(sentKey(0))
+  })
+
+  it('reuses the key when no response arrived (network loss or abort)', async () => {
+    fetchMock
+      .mockRejectedValueOnce(new TypeError('Network request failed'))
+      .mockResolvedValueOnce(jsonResponse(200, { document, idempotent: true }))
+
+    await expect(generateMeetingDocumentOnce(options)).rejects.toMatchObject({ code: 'network' })
+    await generateMeetingDocumentOnce(options)
+
+    expect(sentKey(1)).toBe(sentKey(0))
+  })
+
+  it('clears the key after success so the next generation is a new operation', async () => {
+    fetchMock.mockResolvedValue(jsonResponse(200, { document, idempotent: false }))
+
+    await generateMeetingDocumentOnce(options)
+    await generateMeetingDocumentOnce(options)
+
+    expect(sentKey(1)).not.toBe(sentKey(0))
+  })
+
+  it('keeps the key when local validation fails before any request is sent', async () => {
+    const pending = await getOrCreateGenerationIdempotencyKey(USER_ID, MEETING_ID, TEMPLATE_ID)
+
+    await expect(generateMeetingDocumentOnce({ ...options, title: '   ' }))
+      .rejects.toMatchObject({ code: 'validation' })
+
+    expect(fetchMock).not.toHaveBeenCalled()
+    expect(await getOrCreateGenerationIdempotencyKey(USER_ID, MEETING_ID, TEMPLATE_ID)).toBe(pending)
+  })
+
+  it('returns the result even when clearing the key fails', async () => {
+    const deps: GenerateMeetingDocumentOnceDeps = {
+      keyStore: {
+        getOrCreate: jest.fn(async () => '66666666-6666-4666-8666-666666666666'),
+        clear: jest.fn(async () => { throw new Error('storage unavailable') }),
+      },
+      generate: jest.fn(async (request: GenerateMeetingDocumentOptions) => {
+        expect(request.idempotencyKey).toBe('66666666-6666-4666-8666-666666666666')
+        return { document, idempotent: false }
+      }),
+    }
+
+    await expect(generateMeetingDocumentOnce(options, deps)).resolves.toMatchObject({ document })
+    expect(deps.keyStore.clear).toHaveBeenCalledWith(USER_ID, MEETING_ID, TEMPLATE_ID)
+  })
+
+  it('maps key-store failures to a service error without calling the server', async () => {
+    const deps: GenerateMeetingDocumentOnceDeps = {
+      keyStore: {
+        getOrCreate: jest.fn(async () => { throw new Error('invalid_generation_identity') }),
+        clear: jest.fn(async () => undefined),
+      },
+      generate: jest.fn(),
+    }
+
+    await expect(generateMeetingDocumentOnce(options, deps)).rejects.toBeInstanceOf(TemplateServiceError)
+    expect(deps.generate).not.toHaveBeenCalled()
+    expect(deps.keyStore.clear).not.toHaveBeenCalled()
+  })
+})
diff --git a/apps/mobile-rn/src/features/templates/generation-idempotency.ts b/apps/mobile-rn/src/features/templates/generation-idempotency.ts
index 019dd8b..a11022a 100644
--- a/apps/mobile-rn/src/features/templates/generation-idempotency.ts
+++ b/apps/mobile-rn/src/features/templates/generation-idempotency.ts
@@ -48,3 +48,17 @@ export async function clearEveryGenerationIdempotencyKey(): Promise<void> {
   const keys = (await AsyncStorage.getAllKeys()).filter((key) => key.startsWith(PREFIX))
   if (keys.length > 0) await AsyncStorage.multiRemove(keys)
 }
+
+/**
+ * Port for the per (user, meeting, template) pending-generation key. The
+ * generation use case depends on this interface, not on AsyncStorage.
+ */
+export interface GenerationKeyStore {
+  getOrCreate: (userId: string, meetingId: string, templateId: string) => Promise<string>
+  clear: (userId: string, meetingId: string, templateId: string) => Promise<void>
+}
+
+export const asyncStorageGenerationKeyStore: GenerationKeyStore = {
+  getOrCreate: getOrCreateGenerationIdempotencyKey,
+  clear: clearGenerationIdempotencyKey,
+}
diff --git a/apps/mobile-rn/src/features/templates/generation-key-policy.ts b/apps/mobile-rn/src/features/templates/generation-key-policy.ts
new file mode 100644
index 0000000..44b6cfd
--- /dev/null
+++ b/apps/mobile-rn/src/features/templates/generation-key-policy.ts
@@ -0,0 +1,55 @@
+/**
+ * Idempotency-key lifecycle policy for meeting document generation.
+ *
+ * The server binds an idempotency key to exactly one generation request row.
+ * Once that row reaches a final state ('succeeded' or 'failed'), or the server
+ * refuses the key outright (hash conflict, quota, permission), reusing the key
+ * can only ever replay that final answer. The key must therefore be discarded
+ * so the next user attempt starts a fresh operation.
+ *
+ * The key is retained only while the server's state for it is unknown or still
+ * running: no response reached the client (network loss, abort, local
+ * pre-flight failure), the server reports the request is still processing, or
+ * the response does not come from the generation function itself (an unknown
+ * 5xx such as a gateway timeout, while the worker may still commit). Retrying
+ * with the same key then converges on the server's real outcome instead of
+ * spending a second generation.
+ *
+ * Pure and IO-free so the full status/error-code matrix can be table-tested.
+ */
+
+export type GenerationAttemptOutcome =
+  | { kind: 'succeeded' }
+  | { kind: 'server-response'; status: number; errorCode: string | null }
+  | { kind: 'no-response' }
+
+export type GenerationKeyDisposition = 'discard' | 'retain'
+
+/** 5xx codes the generation function emits only after marking the row failed. */
+const TERMINAL_SERVER_FAILURE_CODES: ReadonlySet<string> = new Set([
+  'provider_timeout',
+  'provider_request_failed',
+  'provider_invalid_response',
+  'commit_failed',
+])
+
+/** 4xx statuses where the server has refused or finalized this key. */
+const TERMINAL_CLIENT_ERROR_STATUSES: ReadonlySet<number> = new Set([400, 403, 404, 429])
+
+export function generationKeyDisposition(
+  outcome: GenerationAttemptOutcome,
+): GenerationKeyDisposition {
+  if (outcome.kind === 'succeeded') return 'discard'
+  if (outcome.kind === 'no-response') return 'retain'
+
+  const { status, errorCode } = outcome
+  if (status >= 200 && status < 300) return 'discard'
+  if (status === 409) return errorCode === 'generation_failed' ? 'discard' : 'retain'
+  if (TERMINAL_CLIENT_ERROR_STATUSES.has(status)) return 'discard'
+  if (status >= 500 && errorCode !== null && TERMINAL_SERVER_FAILURE_CODES.has(errorCode)) {
+    return 'discard'
+  }
+  // 401 (session expired before the claim ran), 500 internal_error and any
+  // gateway-produced 5xx leave the key's server state unknown.
+  return 'retain'
+}
diff --git a/apps/mobile-rn/src/features/templates/template-service.ts b/apps/mobile-rn/src/features/templates/template-service.ts
index e1a5a82..0f042db 100644
--- a/apps/mobile-rn/src/features/templates/template-service.ts
+++ b/apps/mobile-rn/src/features/templates/template-service.ts
@@ -9,6 +9,14 @@ import type {
 } from '@d3ro/api-client'
 import { SUPABASE_URL } from '@d3ro/core/supabase-config'
 import { supabase } from '../../lib/supabase'
+import {
+  asyncStorageGenerationKeyStore,
+  type GenerationKeyStore,
+} from './generation-idempotency'
+import {
+  generationKeyDisposition,
+  type GenerationAttemptOutcome,
+} from './generation-key-policy'
 import type {
   GenerateMeetingDocumentOptions,
   GeneratedMeetingDocument,
@@ -29,11 +37,18 @@ export type TemplateServiceErrorCode =
   | 'server'
   | 'validation'
 
+/** The HTTP answer the server gave, when an error came from a server response. */
+export interface TemplateServiceResponseInfo {
+  status: number
+  errorCode: string | null
+}
+
 export class TemplateServiceError extends Error {
   constructor(
     public readonly code: TemplateServiceErrorCode,
     message: string,
     public readonly retryable = false,
+    public readonly response: TemplateServiceResponseInfo | null = null,
   ) {
     super(message)
     this.name = 'TemplateServiceError'
@@ -357,14 +372,21 @@ export function renderDictationTemplate(
 
 function generationError(status: number, body: unknown): TemplateServiceError {
   const code = isRecord(body) && typeof body.error === 'string' ? body.error : ''
-  if (status === 401) return new TemplateServiceError('auth', code)
-  if (status === 403) return new TemplateServiceError('forbidden', code)
-  if (status === 404) return new TemplateServiceError('not-found', code)
-  if (status === 409) return new TemplateServiceError('in-progress', code, true)
-  if (status === 429) return new TemplateServiceError('quota', code, true)
-  if ([502, 503, 504].includes(status)) return new TemplateServiceError('provider', code, true)
-  if (status === 400) return new TemplateServiceError('validation', code)
-  return new TemplateServiceError('server', code || 'Document generation failed', true)
+  const response: TemplateServiceResponseInfo = { status, errorCode: code || null }
+  if (status === 401) return new TemplateServiceError('auth', code, false, response)
+  if (status === 403) return new TemplateServiceError('forbidden', code, false, response)
+  if (status === 404) return new TemplateServiceError('not-found', code, false, response)
+  if (status === 409 && code === 'generation_failed') {
+    // The previous attempt with this key failed for good; a new attempt can succeed.
+    return new TemplateServiceError('server', code, true, response)
+  }
+  if (status === 409) return new TemplateServiceError('in-progress', code, true, response)
+  if (status === 429) return new TemplateServiceError('quota', code, true, response)
+  if ([502, 503, 504].includes(status)) {
+    return new TemplateServiceError('provider', code, true, response)
+  }
+  if (status === 400) return new TemplateServiceError('validation', code, false, response)
+  return new TemplateServiceError('server', code || 'Document generation failed', true, response)
 }
 
 function isRecord(value: unknown): value is Record<string, unknown> {
@@ -416,6 +438,71 @@ export async function generateMeetingDocument(
   }
 }
 
+export interface GenerateMeetingDocumentOnceOptions
+  extends Omit<GenerateMeetingDocumentOptions, 'idempotencyKey'> {
+  userId: string
+}
+
+export interface GenerateMeetingDocumentOnceDeps {
+  keyStore: GenerationKeyStore
+  generate: (options: GenerateMeetingDocumentOptions) => Promise<GeneratedMeetingDocument>
+}
+
+const DEFAULT_GENERATE_ONCE_DEPS: GenerateMeetingDocumentOnceDeps = {
+  keyStore: asyncStorageGenerationKeyStore,
+  generate: generateMeetingDocument,
+}
+
+/** Maps a failed attempt to what the client actually learned from the server. */
+export function generationAttemptOutcome(error: unknown): GenerationAttemptOutcome {
+  if (error instanceof TemplateServiceError && error.response !== null) {
+    return {
+      kind: 'server-response',
+      status: error.response.status,
+      errorCode: error.response.errorCode,
+    }
+  }
+  return { kind: 'no-response' }
+}
+
+/**
+ * Generates one meeting document and owns its idempotency key's lifecycle:
+ * the key for (user, meeting, template) is reused across ambiguous retries and
+ * discarded once the server has given a final answer for it, success or not.
+ */
+export async function generateMeetingDocumentOnce(
+  options: GenerateMeetingDocumentOnceOptions,
+  deps: GenerateMeetingDocumentOnceDeps = DEFAULT_GENERATE_ONCE_DEPS,
+): Promise<GeneratedMeetingDocument> {
+  const { userId, ...request } = options
+  let idempotencyKey: string
+  try {
+    idempotencyKey = await deps.keyStore.getOrCreate(userId, request.meetingId, request.templateId)
+  } catch (error) {
+    throw toServiceError(error)
+  }
+
+  let outcome: GenerationAttemptOutcome
+  let generated: GeneratedMeetingDocument | null = null
+  let failure: unknown = null
+  try {
+    generated = await deps.generate({ ...request, idempotencyKey })
+    outcome = { kind: 'succeeded' }
+  } catch (error) {
+    failure = error
+    outcome = generationAttemptOutcome(error)
+  }
+
+  if (generationKeyDisposition(outcome) === 'discard') {
+    // A failed cleanup only costs one extra replay of the final answer.
+    await deps.keyStore
+      .clear(userId, request.meetingId, request.templateId)
+      .catch(() => undefined)
+  }
+  if (generated === null) throw toServiceError(failure)
+  return generated
+}
+
 export function subscribeToTemplates(
   userId: string,
   onRemoteChange: () => void,
diff --git a/apps/mobile-rn/src/screens/MeetingDetailScreen.tsx b/apps/mobile-rn/src/screens/MeetingDetailScreen.tsx
index 4eb4ad3..fcbc777 100644
--- a/apps/mobile-rn/src/screens/MeetingDetailScreen.tsx
+++ b/apps/mobile-rn/src/screens/MeetingDetailScreen.tsx
@@ -29,9 +29,7 @@ import {
   type PreparedPortableFile,
 } from '../features/data-portability'
 import {
-  clearGenerationIdempotencyKey,
-  generateMeetingDocument,
-  getOrCreateGenerationIdempotencyKey,
+  generateMeetingDocumentOnce,
   loadTemplateLibrary,
   TemplateServiceError,
 } from '../features/templates'
@@ -417,18 +415,13 @@ export default function MeetingDetailScreen({
     setBusyKey('document-generate')
     setError(null)
     try {
-      const idempotencyKey = await getOrCreateGenerationIdempotencyKey(
-        user.id,
-        meetingId,
-        templateId,
-      )
       const title = `${detail.meeting.title?.trim() || t('mobile.meetings.untitled')} · ${selectedDocumentTemplate.name}`
         .slice(0, 160)
-      const generated = await generateMeetingDocument({
+      const generated = await generateMeetingDocumentOnce({
+        userId: user.id,
         accessToken: session.access_token,
         meetingId,
         templateId,
-        idempotencyKey,
         title,
       })
       setDetail((current) => {
@@ -444,7 +437,6 @@ export default function MeetingDetailScreen({
         }
       })
       setExpandedDocumentId(generated.document.id)
-      await clearGenerationIdempotencyKey(user.id, meetingId, templateId).catch(() => undefined)
     } catch (requestError) {
       setError(templateErrorMessage(requestError, t))
     } finally {