Initial TrueGrowth source import

openspec/specs/markdown-media-embeds/spec.md

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+# markdown-media-embeds Specification
+
+## Purpose
+TBD - created by archiving change add-kb-asset-embeds-and-markdown-card-rendering. Update Purpose after archive.
+## Requirements
+### Requirement: 知识库 Markdown 编辑器必须支持素材库引用
+The system SHALL allow users to insert media-library assets into knowledge-base markdown notes without duplicating media content into the note body.
+
+#### Scenario: Insert an asset into a note
+- **GIVEN** the user is editing a knowledge-base note
+- **WHEN** the user opens the media library and selects an asset
+- **THEN** the editor SHALL insert a markdown asset reference into the note content
+- **AND** the inserted content SHALL preserve the referenced asset id
+
+### Requirement: Markdown 渲染必须支持图片、视频、音频素材引用
+The system SHALL resolve markdown asset references and render the referenced media inline in markdown preview surfaces.
+
+#### Scenario: Render an image asset reference
+- **GIVEN** a markdown body contains an `asset://` reference to an image asset
+- **WHEN** the markdown is rendered in preview
+- **THEN** the system SHALL display the referenced image inline
+
+#### Scenario: Render a video or audio asset reference
+- **GIVEN** a markdown body contains an `asset://` reference to a video or audio asset
+- **WHEN** the markdown is rendered in preview
+- **THEN** the system SHALL display an inline player for the referenced media
+
+### Requirement: 画布 Markdown 卡片必须复用同一套素材渲染
+The system SHALL render markdown asset references consistently in canvas markdown cards and in the knowledge-base editor preview.
+
+#### Scenario: Display the same note content in a canvas card
+- **GIVEN** a markdown body with media-library asset references is shown inside a canvas markdown card
+- **WHEN** the card is rendered
+- **THEN** the card SHALL display the same inline media presentation as the knowledge-base preview
+
+### Requirement: 缺失素材必须有安全降级
+The system SHALL replace unresolved markdown asset references with a visible placeholder instead of failing the render.
+
+#### Scenario: Referenced asset has been deleted
+- **GIVEN** a markdown body references an asset id that no longer exists
+- **WHEN** the markdown is rendered
+- **THEN** the system SHALL show a missing-asset placeholder in place of the media
+