面试题库

7 天 Agent Skills：把经验做成可复用能力

D5 手写一个 skill 运行时：扫描、frontmatter 解析、注入系统提示、按需读取正文

• 你的运行时解析到一份不合规范的 SKILL.md，是拒绝加载还是降级加载？另外，两个作用域里有同名 skill 时你怎么处理？When your runtime parses a SKILL.md that violates the spec, do you refuse to load it or degrade gracefully? And how do you handle a name collision across scopes?

  国内高频海外高频进阶#agent-skills#runtime#error-handling

  分析过程 · 先想清楚再作答

  1. 两个小问共用一个立场：**运行时是给人干活的，不是校验器。** 先把这句说出来，后面两半都好答。
  2. 宽松加载这一半要给出可判定的边界，不能只说「尽量宽松」。**唯一的硬性淘汰是缺 description**——少了它这个 skill 在发现阶段没有触发面，永远不会被选中，留在清单里只是白占 token。
  3. 其余一律只告警仍然加载：名字与目录名不一致、名字用了大写或下划线、描述超过上限。它们影响质量，不影响能不能用。
  4. 举一个最常见的畸形做证据：YAML 值里没加引号的冒号会让正规解析器判整行非法，进而拒绝整个文件。正确的兜底顺序是先用完整 YAML 解析，失败了再退回按行取值，只抠出认识的那几个标量字段。
  5. 同名冲突这一半，方向不是重点，**处理方式才是**。跨客户端通行约定是项目级压过用户级，但 Claude Code 的顺序是企业级、个人级、项目级由高到低，两种都合理，关键是固定一种并保持一致。
  6. 最糟的做法是静默丢弃：用户改了项目里那份，行为一点没变，他会去怀疑缓存和保存，就是不会想到别处有个同名的。**必须留一条警告并把两个路径都打出来**，那条日志是排查这类问题的第一现场。
  7. 可预期的追问是「宽松会不会把坏 skill 放进来」。答案是这两件事的层次不同：宽松说的是格式容错，安全靠的是来源信任与工具权限，不能拿格式校验当安全边界。

  How to reason about it · think before answering

  1. Both halves share one stance: a runtime exists to get work done, not to validate. State that first.
  2. For loose loading, give a decidable boundary. The only hard rejection is a missing description: without it the skill has no trigger surface, can never be selected, and only wastes catalog tokens.
  3. Everything else warns and still loads: a name that differs from the directory, a name using capitals or underscores, an over-long description. These hurt quality but not usability.
  4. Cite the most common malformation as evidence: an unquoted colon inside a YAML value makes a strict parser reject the whole file. The right fallback order is full YAML parsing first, then a line-wise field reader that extracts only the scalar fields you know.
  5. For collisions, the direction matters less than the handling. The cross-client convention is project over user, while Claude Code orders enterprise, personal, then project. Both are defensible; pick one and stay consistent.
  6. The worst handling is silent discard. The user edits the project copy, nothing changes, and they suspect caching or a failed save rather than a same-named skill elsewhere. Always log a warning that prints both paths.
  7. Expected follow-up: does loose loading let bad skills in? These are different layers. Looseness is format tolerance; safety comes from source trust and tool permissions, not from schema validation.

  答题要点

  • 立场是运行时不是校验器，默认降级加载。
  • 唯一硬性淘汰是缺 description，因为它没有触发面、永远不会被选中。
  • 名字不一致、名字不合规、描述超长都只记诊断仍然加载。
  • 解析顺序是先完整 YAML、失败再按行取值兜底，专治值里没加引号的冒号。
  • 同名冲突要固定一种优先级并保持一致，绝不静默丢弃，警告里要带上两个路径。

  Key points

  • A runtime is not a validator; degrade by default.
  • The only hard rejection is a missing description, which leaves no trigger surface.
  • Name mismatches, invalid names and over-long descriptions warn but still load.
  • Parse with full YAML first, then fall back to line-wise field reading for unquoted colons.
  • Fix one collision priority, keep it consistent, and never discard silently: log both paths.