同步剩余文档的双告警并存规则

外部编辑器 API 技能文档、外部生成 Worker 化方案和图片画布编辑器 MVP
接入方案仍写着通用 warning 与 sliceWarning 互斥、并以通用告警优先，与
已放开并存的 openapi 契约和 8ed85e17f 的队列 / inline 归一实现不一致。

四处统一改为：仅 postprocess-failed-source-preserved 与 sliceWarning 互斥
（该失败不进入拆分），风格归一化与像素规整产生的通用 warning 可与
sliceWarning 并存且两条都必须展示；同步补充队列侧的拼接与 code 收敛规则。

UI 设计图素材提取不接受 style 参数也不走像素规整，其文档中的互斥表述
仍然成立，未改动。

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

.codex/skills/genarrative-external-editor-api/SKILL.md

@@ -324,7 +324,7 @@ Character image generation (including character redraw through `kind: "character
 
 - Apply the returned `project` and media snapshots before interpreting optional derivatives: character responses use `resource` / `asset`, while icon spritesheet and UI extraction responses use `spritesheetResource` / `spritesheetAsset`. When `warning.code` is `postprocess-failed-source-preserved`, the saved provider source image is the authoritative main result. Character output has no transparent derivative; icon spritesheet and UI extraction output have neither a transparent spritesheet nor slices. Display `warning.reason` directly, and do not synthesize missing derivatives or restart generation.
 - `sliceWarning` is a separate condition used only when transparent spritesheet post-processing succeeded but automatic slicing failed. Keep `sliceWarning.reason` as the original diagnostic and continue using the complete transparent spritesheet; a UI may add context when displaying it, but must not rewrite the stored reason.
-- The service contract keeps `warning` and `sliceWarning` mutually exclusive. As defensive handling for a malformed response containing both, treat the general `warning` as authoritative and do not misclassify the source-preserved result as a slicing-only warning.
+- `warning` and `sliceWarning` are mutually exclusive only for `postprocess-failed-source-preserved`, because a failed transparent post-process never reaches slicing. Since 2026-07-29 a general `warning` may also come from image-style normalization (`unsupported-image-style`) or pixel-art snapping, and those can coexist with `sliceWarning` in the same response. Display both reasons; do not drop either one and do not misclassify a source-preserved result as a slicing-only warning.
 
 ## Guardrails
 

.codex/skills/genarrative-external-editor-api/references/api-selection.md

@@ -84,7 +84,7 @@ Character image generation (including character redraw through `kind: "character
 
 - Consume the returned `project` and media snapshots as authoritative: character responses use `resource` / `asset`, while icon spritesheet and UI extraction responses use `spritesheetResource` / `spritesheetAsset`. `warning.code: "postprocess-failed-source-preserved"` means the saved provider source is the main result. Character output has no transparent derivative, while icon spritesheet and UI extraction have no transparent spritesheet and no slices. Display `warning.reason` directly; do not construct missing assets or retry the provider generation from scratch.
 - `sliceWarning` is only for a transparent spritesheet that was created successfully but could not be split automatically. Use the complete transparent spritesheet and preserve `sliceWarning.reason` as the original diagnostic; it is not a post-processing/source-preserved warning.
-- The service contract keeps `warning` and `sliceWarning` mutually exclusive. If a malformed response contains both, prioritize the general `warning` over `sliceWarning` defensively.
+- `warning` and `sliceWarning` are mutually exclusive only for `postprocess-failed-source-preserved`, because that failure never reaches slicing. A general `warning` produced by image-style normalization (`unsupported-image-style`) or pixel-art snapping can coexist with `sliceWarning`; render both reasons instead of picking one.
 
 ## Reference Image Upload