docs(lark-doc): document media token domain binding and SHA-256 caching lifecycle

[jiezhengj]

Summary

Documents the lifecycle, authorization boundary, and revision storage management of media file_token in Lark Docx, preventing broken images from cross-document copying and avoiding storage bloat from repeated media uploads.

Key Enhancements

1. Document-Domain Token Binding:

   • Clarified that media tokens generated via docs +media-insert (<img src="file_token">) are cryptographically and contextually bound to the host document they were originally uploaded to.

2. Common Pitfall Warning (Temporary Import Token Degradation):

   • Documented the pitfall where creating a temporary document via drive +import and extracting its XML tokens to overwrite a target document results in broken images due to permission boundary violations across document domains.

3. Standard Solution Pattern:

   • Instructs agents and developers to upload media directly into the target document's scope via lark-cli docs +media-insert --doc <target_doc_id> before embedding.

4. Revision Storage Bloat & SHA-256 Hash Caching Guidelines:

   • Clarified that Lark Docx retains orphan media across historical revision snapshots without automatic garbage collection (GC).
   • Documented the standard SHA-256 hashing pattern for incremental local media token reuse, completely eliminating multi-gigabyte storage accumulation during frequent sync operations.

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Validated across document and wiki image sync operations.

Summary by CodeRabbit

• Documentation
  • Added guidance to prevent repeated media uploads from creating unnecessary document revisions.
  • Documented SHA-256-based caching to reuse unchanged media and upload files only when content changes or a reupload is requested.

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ℹ️ Recent review info

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• skills/lark-doc/references/lark-doc-media-insert.md

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📝 Walkthrough

Walkthrough

更新媒体插入文档。文档要求按目标文档和图像 SHA-256 哈希缓存 file_token，复用未变化图像的令牌，并仅在图像变化或强制重新上传时上传。

Changes

媒体插入缓存指南

Layer / File(s)	Summary
媒体令牌缓存规则 skills/lark-doc/references/lark-doc-media-insert.md	新增媒体历史副本控制指南。文档要求持久化目标文档、图像哈希与 file_token 的映射，并规定重新上传条件。

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to 81fe4

This documentation-only change is merge-ready after normal checks and review, with no actionable merge-blocking risk remaining.

Suggested reviewers: liangshuo-1

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the documentation changes for media token binding and SHA-256 caching.
Description check	✅ Passed	The description clearly explains the scope, changes, and validation, although it does not use every template heading.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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Actionable comments posted: 1

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Inline comments:
In `@skills/lark-doc/references/lark-doc-media-insert.md`:
- Line 120: Update the media upload instruction to use the document ID
terminology established for the --doc argument, replacing the ambiguous target
document token placeholder with target document ID or doc_id while preserving
the existing CLI behavior and media token usage.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 767fbf56-c2ef-4d3d-82e0-84765e0e1e03

📥 Commits

Reviewing files that changed from the base of the PR and between 423e81f and 987b10a.

📒 Files selected for processing (1)

• skills/lark-doc/references/lark-doc-media-insert.md

Included review availability: Your plan provides up to 10 included reviews per hour; 6 remain after this review.