feat: JSON 작성기 경량화 — 기본값 생략·한글 비이스케이프 (corpus 3,043 → 378 KB, 스키마 그대로)

CHANGELOG.md

@@ -6,6 +6,45 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed — one document is the same bytes in both editors (2026-10-01)
+
+- JSON and `.flow` loads join equal-format neighbouring runs, as the HTML and RTF readers already did and as the port
+  does: a file split one line into any number of runs, and the same content now loads as the same model.
+- Colours are written `#AARRGGBB` in upper case, as the format states and the port writes. `Color.ToString()` wrote a
+  known colour's NAME (`"Red"`) and anything else in lower case. Every reader takes either.
+- `Alt` and `VAlign` are written where the port writes them (field order is the written order).
+- `tests/…/Fixtures/format-1.0-interchange.json` uses every field in the canonical form. The port holds the same file
+  and the same test — read it, write it back, byte for byte — so a change to what either editor writes fails in the
+  repository that made it.
+
+### Changed — the JSON writer leaves out what every reader assumes (2026-10-01)
+
+**The schema is unchanged** (still `"1.0"`), and every reader since 1.0 reads the new output exactly as before —
+checked directly: the tree before this change read 18 documents written the new way (the fixpoint set and corpus
+pages) and produced, byte for byte, what it produces from its own output, as JSON and as `.flow`.
+
+- Fields equal to the value a reader assumes when they are absent are not written: a run's `Bold`/`Italic`/
+  `Underline`/`Strikethrough` false and `FontSize` 10, a paragraph's `HeadingLevel`, `ListLevel`, `Indent`, `IsQuote`,
+  `MarginRight`, `ListType` `None`, `TextAlignment` `Left`, each block kind's own default bottom margin, `Type`
+  `Paragraph`/`Run`, a table's `Rows`/`Columns` (readers rebuild them) and its span grids when nothing is merged.
+  The legacy `IsListItem` — documented as never written — had been written on every paragraph.
+- **Non-ASCII text is written as it is.** Korean went out as `정보…`, six bytes a character and unreadable
+  in a diff. Characters HTML is sensitive to (`< > & ' "`) are still escaped, so the JSON can be embedded in a page.
+- **Not indented.** Indentation was half of every document.
+- Measured on `tests/corpus`: 240.6 → 37.7 KB, 3,043 → 378 KB; the kitchen-sink document 15.9 → 1.3 KB. A `.flow`
+  package changes little on disk (its `document.json` was already deflated).
+- ⚠ **Hosts that compare saved JSON byte for byte** (snapshot tests) will see the new form.
+
+Also:
+- **A newer major format is refused** by `LoadJson`, `LoadJsonAsync` and `LoadPackageAsync` (`JsonException`, like a
+  damaged file): it would come in with what this reader does not know turned into empty paragraphs, and a save would
+  write that over the file. `DocumentSerializer.Deserialize` stays lenient. An unknown block or inline `Type` within
+  the same major is read as text and reported to `RichEditorDiagnostics`.
+- A paragraph whose `MarginTop` a host set to `Block.AutoTopMargin` (NaN) threw on save — JSON has no NaN.
+- `docs/DOCUMENT_FORMAT.md` caught up with the code: damaged input throws (it said "empty document"), the default page
+  margin is 15 mm (it said 12.7/10.6), an absent `MarginTop` on a table, picture or divider is automatic (it said 0),
+  and the round-35 import bounds.
+
 ### Fixed — round 35: a full audit; the size and depth of untrusted input (2026-10-01)
 
 Every source file was read. Most of what turned up is one axis earlier rounds never measured: how LARGE and how

Project_Roadmap.md

@@ -46,6 +46,12 @@ PR #48·#49·#50), 실기 후속도 PR #52로 들어왔다. 남은 것은 게시
 게시 절차: `<Version>` → Unshipped를 Shipped로 이관 → CHANGELOG `[Unreleased]` → 버전 → README 배지(en/ko) → PR로 3-OS CI →
 `v1.3.0` 태그 push(**사람이 실행**, Trusted Publishing) → **nuget.org 패키지 페이지 육안 확인**.
 
+**1b. JSON 작성기 경량화 (2026-10-01)** — 스키마 그대로, 작성기만: 기본값 필드 생략·한글 비이스케이프·들여쓰기 없음.
+corpus 240.6 → 37.7 KB, 3,043 → 378 KB. **구 판독기 호환은 구 트리로 직접 확인**(18개 문서, JSON·.flow 바이트 동일).
+메이저 버전이 더 높은 문서는 로드 경로가 거부, 모르는 `Type`은 진단 보고. 명세(`docs/DOCUMENT_FORMAT.md`)의 어긋남도 정정.
+사용자 결정: 들여쓰기 옵션 없이 제거, 메이저 거부 도입. 포트도 같은 형식이라 같이 옮길 것.
+포트 대조(라운드35)는 끝났다 — WinUIRichEditor PR #62(14건 백포트, 상류 픽셀 상한은 포트에 불필요).
+
 **1a. 라운드35 · 전수 감사 (2026-10-01, PR #59 머지)** — `src` 약 19,500줄을 모델 → 포매터 → 컨트롤 순으로 읽었다. 결함 **16건**
 (프로세스 종료 3·데이터 소실 3·보안 1), 전부 빨강 먼저 → 수정 → 개별 반증. 대부분 이전 라운드가 재지 않은 **입력의 크기·깊이** 축이다. 테스트: `Round35AuditTests`.
 - 치명(프로세스 종료, catch 불가): HTML `<div>` 2,000겹(11 KB) 붙여넣기, 중첩 표 400단(RTF `\itap` 무제한) 렌더 — 스택 오버플로.