ZZEM Sprints
Explore Clusters System
← Timeline

AI Webtoon Sprint

in-progress

PRD

Sprint PRD: ai-webtoon

Source

Scope Summary

사진 1장으로 나만의 AI 웹툰 1화를 생성하고, 자동/직접 이어가기로 연재 구조를 형성해 크레딧 재소비·재방문을 유도하는 기능.

핵심 가설

이어가기 구조를 제공하면 유저가 다음 화 궁금증으로 재방문해 크레딧을 재소비한다.

성공 기준 (KPI)

  • 웹툰 생성 비중 전체 대비 10% 이상
  • 리텐션 커브 플래토 형성
  • 크레딧 재구매 발생 여부

Feature Groups (초안 — Phase 2에서 확정)

US 제목 범위
US-1 웹툰 탭 템플릿 탐색 홈 [추천/웹툰/무료] 탭 + 웹툰 탭 리스트 + 빈 상태
US-2 템플릿 상세 미리보기 상세 페이지 + 프리뷰 + 만들기 CTA
US-3 사진 업로드 → 1화 생성 입력 화면 + 2단계 생성 (1단계 업로드, 2단계 모델 호출) + 결과
US-4 자동 이어가기 결과물에서 다음 화 자동 생성 (크레딧 차감)
US-5 직접 이어가기 유저 줄거리 입력으로 다음 화 생성

생성 모델

  • Model: fal-ai/nano-banana-2/edit (i2i)
  • Input: image_urls[] + prompt (Jayla 초기 시스템 프롬프트 + 줄거리 + 템플릿 메타)
  • Output: 컷이 합성된 단일 웹툰 페이지 이미지 1장

주요 제약/에러

  • 유해 이미지 감지 → AC 2.3.6
  • 콜백 실패 → BR-2 (크레딧 차감 없음)
  • 정상 소요 시간 초과 → AC 2.3.8 (timeout)

구현 주의

  • FAL_AI_MODEL_INPUT_MAP 에 nano-banana-2/edit 엔트리 추가 필요
  • 참조 이미지는 image_urls[]에 포함 (BR-12 / §5 ASK 참조)

References

  • Acceptance Criteria, Business Rules, 용어, 리스크 등 상세는 원본 PRD 링크 참조.
  • Figma 프레임 node-id=37289-168285 (Wrtn-X_쨈_Sprint-File)

Sprint Artifacts

파일 생성 시점
sprint-config.yaml Phase 1
tasks/{app,backend}/*.md Phase 2
contracts/api-contract.yaml Phase 2
prototypes/app/*/ Phase 3
evaluations/group-*.md Phase 4
retrospective/ Phase 6

Report

Sprint Report — ai-webtoon

Date: 2026-04-15 Sprint branch: sprint/ai-webtoon PRD source: docs/prds/PRD-ai-webtoon-v1.2.md Verdict: PASS (3 / 3 groups, 0 fix loops, 4 Major follow-ups deferred)

Executive Summary

사진 1장 → AI 웹툰 1화 생성 + 자동/직접 이어가기 연재 구조 전체 파이프라인을 3개 그룹으로 분해 구현, 모든 그룹이 첫 평가에서 PASS. Critical 0건, Major 4건은 모두 non-blocking(자가 치유 / 계약 수준 안전)으로 다음 스프린트로 이월.

PRD Coverage

Metric Value
Total AC 22
Fulfilled 18
Partially fulfilled 4
Unfulfilled 0
Fulfillment rate 0.82

Build Results

Group Scope Verdict Fix loops Critical Major Minor
group-001 be-001 (templates + schemas) + app-001 (tab + detail + MY) PASS 0 0 0 0
group-002 be-002 (generation pipeline + fal-ai callback) + app-002 (generate screen + polling) PASS 0 0 2 3
group-003 be-003 (continuation + series queries + seen + test-seed) + app-003 (series detail + manual continue) PASS 0 0 2 3

Quality Metrics

  • First-pass rate: 3/3 = 100%
  • Average fix cycles: 0.0
  • Critical: 0 | Major: 4 (deferred) | Minor: 6
  • Issues fixed: 0 | Issues deferred: 10
  • E2E flows authored: 8 (executed: 0 — Phase 5 simulator gate)

Issues

Critical

None.

Major (deferred follow-ups)

ID Group Pattern Root cause Recommendation
G002-M1 group-002 Concurrency cap source drift (webtoon DB-sum vs meme Redis slot) integration / dependency Unify webtoon submit into reserveGenerationSlotOrThrow
G002-M2 group-002 episodeNumber gap when $inc precedes failed insert edge_case Compensating $dec on insert catch, or doc gap-allowed contract
G003-M1 group-003 Retry CTA hardcodes AUTO — MANUAL intent lost scope_creep Persist originType on episode; route MANUAL retry to input screen
G003-M2 group-003 hasUnseenEpisode=true dual flip site (PENDING-append + COMPLETED-callback) code_quality Remove flag set from incrementLastEpisode $set; flip only via markHasUnseenTrue

Minor

Area Note
app-002 402 UX Toast + Paywall nav instead of InsufficientCreditSheet (behaviourally equivalent)
HMAC canonicalizePayload is shallow (top-level only) — OK for flat payload
app-002 buildCallbackUrl double-includes generationId; harmless
app-002 240s setTimeout not explicitly cleared on terminal status (GC-safe)
app-003 Duplicated error mapping between series-detail and manual-continue screens
app-003 After manual submit + goBack, new-episode auto-scroll does not fire
be-003 N+1 series-list query — buildSeriesSummary refetches episodes per row

Systemic Patterns

Positive (load-bearing reuse):

  • Shared credit/concurrency/HMAC helper reuse across submit→continuation — zero forked logic in be-003.
  • Race-safe append (atomic $inc + unique (seriesId, episodeNumber) compound index backstop) validated by 5-parallel spec.
  • Single useWebtoonGenerationPolling(generationId) hook reused across app-002 + app-003 with AppState listener + 240s timeout.

Regressions (→ contract amendments):

  • Two pipelines sharing a cap must share the atomic counter source (G002-M1).
  • 2-step atomic sequences must declare gap-allowed vs compensate (G002-M2).
  • Retry CTA must preserve originating mode/payload; silent fallback forbidden (G003-M1).
  • Domain state flags must flip from a single domain-service helper; repository write side-effects forbidden (G003-M2).

Deliverables

Code (3 repos)

  • sprint-orchestrator: sprint artifacts, checkpoints, evaluations, contracts, retrospective → sprint/ai-webtoon
  • wrtn-backend: apps/meme-api/src/**/webtoon-*, fal-ai adapter, scheduler, webhook → sprint/ai-webtoon
  • app-core-packages (MemeApp): webtoon presentation + domain + data + navigation + hooks + Maestro flows → sprint/ai-webtoon

Screens

  • Home tabs (웹툰 탭 추가) + WebtoonFloatingButton + WebtoonEmptyView
  • WebtoonTemplateDetailScreen (preview + CTA)
  • WebtoonGenerateScreen (INPUT / GENERATING / RESULT / FAILED states)
  • WebtoonSeriesDetailScreen (FIRST/LAST_CONTINUE focus, inline polling, ContinuationCtaBar)
  • WebtoonManualContinueScreen (purple banner + 500-char input)
  • MyWebtoonScreen (list, N-badge, split hitboxes) + MyWebtoonEmptyView

API Contract (10+ endpoints)

  1. GET /webtoon/templates
  2. GET /webtoon/templates/{id}
  3. GET /webtoon/series
  4. GET /webtoon/series/{id}?focus=FIRST|LAST_CONTINUE
  5. POST /webtoon/series/{id}/seen
  6. POST /webtoon/generations (1화 submit)
  7. GET /webtoon/generations/{generationId} (status poll)
  8. POST /webtoon/series/{seriesId}/episodes (continuation AUTO/MANUAL)
  9. POST /webhook/webtoon/{generationId} (internal fal-ai callback, HMAC)
  10. POST /__test__/webtoon/series/seed (dev-only, double-gated)
  11. POST /__test__/webtoon/series/clear (dev-only, origin-scoped cleanup)

Artifacts

  • sprint-config.yaml, PRD.md
  • contracts/api-contract.yaml
  • tasks/{backend,app}/00{1,2,3}-*.md
  • evaluations/group-00{1,2,3}.md
  • checkpoints/group-00{1,2,3}-summary.md
  • prototypes/app/ (Phase 3)
  • retrospective/{gap-analysis,pattern-digest,deferred-items}.yaml
  • 8 Maestro flows (MemeApp e2e)

PR Links

Improvements for Next Sprint

  1. Unify concurrency cap counter source — webtoon submit → reserveGenerationSlotOrThrow (closes G002-M1).
  2. Compensate counter on insert failure or document gap-allowed (closes G002-M2).
  3. Persist originType on episode; MANUAL retry → ManualContinueInputScreen (closes G003-M1).
  4. Single flip site for hasUnseenEpisode — remove from incrementLastEpisode (closes G003-M2).
  5. Extract shared handleContinuationError util (series-detail ↔ manual-continue duplication).
  6. Execute 8 Maestro flows in simulator gate.
  7. Fill FE jest coverage for webtoon domain/data/presentation.
  8. Batch episode lookup in buildSeriesSummary to eliminate N+1.

Timeline

  • Phase 1 (Plan): 2026-04-15 — sprint-config.yaml + PRD.md extract
  • Phase 2 (Design): 2026-04-15 — 6 task specs + api-contract.yaml
  • Phase 3 (Prototype): 2026-04-15 — webtoon screens prototyped; no amendments
  • Phase 4 (Build): 2026-04-15 — 3 groups, all PASS first pass, 0 fix loops
  • Phase 6 (Retro): 2026-04-15 — this report

Commits

Backend (wrtn-backend)

  • 0e4c42d8 feat(be-001): webtoon templates + series/episode schema + read endpoints
  • da3deb23 feat(be-002): webtoon generation pipeline + fal-ai callback + concurrency cap
  • 5d64c2a8 feat(be-003): webtoon continuation + series queries + seen + test-seed

App (app-core-packages / MemeApp)

  • 32a97fbb feat(app-001): webtoon tab + template detail + MY webtoon list
  • c8c78696 feat(app-002): webtoon generate screen + 5s polling + result/error branches
  • cf938b60 feat(app-003): series detail + continuation (auto/manual) + inline errors

Sprint (sprint-orchestrator)

  • 433b9ca, dc8470b, 2bc11cf — sprint artifact checkpoints per group