Python: skill name validation improvements

[Copilot]

• Update VALID_NAME_RE to reject consecutive hyphens
• Update error message in _validate_skill_metadata to mention consecutive hyphens (split to stay within 120-char line limit)
• In _read_and_parse_skill_file, enforce frontmatter name matches parent directory name
• Add tests: consecutive hyphens rejected
• Add tests: directory name mismatch rejected
• Fix E501 lint error (line too long)

Original prompt

Create a PR in microsoft/agent-framework that ports the validation improvements from .NET PR #4526 to the Python agent skills implementation.

Context

• .NET PR: .NET: Improve skill name validation: reject consecutive hyphens and enforce directory name match #4526 (merged)
• Python skills implementation: python/packages/core/agent_framework/_skills.py

Required behavior changes (Python)

1. Skill name validation must reject consecutive hyphens

• Update VALID_NAME_RE from the current pattern that allows consecutive hyphens to a pattern that disallows them (equivalent to .NET regex: ^[a-z0-9]([a-z0-9]*-[a-z0-9])*[a-z0-9]*$).
• Update the corresponding validation error message in _validate_skill_metadata to mention that consecutive hyphens are not allowed.

2. File-based skills: enforce that the name: from SKILL.md frontmatter matches the parent directory name

• Implement this check in the file-based skill loading path after frontmatter extraction (best location: _read_and_parse_skill_file(skill_dir_path)), because it has access to the skill directory path.
• On mismatch: log an error similar to .NET (include SKILL.md path, frontmatter name, directory name) and exclude the skill (return None).
• For code-defined skills (created in Python code), do not apply directory matching.

3. Tests

• Add/extend Python unit tests to cover:
  • invalid skill names with consecutive hyphens (e.g. consecutive--hyphens) are rejected.
  • directory name mismatch (folder wrong-dir-name containing SKILL.md with frontmatter name: actual-skill-name) is rejected.
• Keep tests consistent with existing repo testing patterns.

Notes

• Ensure behavior remains case-sensitive for directory name match (align with .NET’s ordinal comparison).
• Keep existing behavior for other invalid names (leading/trailing hyphen, spaces, etc.).
• Run/adjust formatting/linting if the repo enforces it.

Files likely to change

• python/packages/core/agent_framework/_skills.py
• Python test file(s) that cover skills discovery/validation (discover via repo search).

Acceptance criteria

• Python skill discovery rejects consecutive-hyphen names.
• Python skill discovery rejects SKILL.md whose name: does not match the containing directory.
• New/updated unit tests pass.

This pull request was created from Copilot chat.

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[SergeyMenshykh]

@copilot fix the failed check:

FAILED: lint in packages/core
Poe => ruff check
E501 Line too long (137 > 120)
--> agent_framework/_skills.py:735:121
|
733 | …
734 | …': Must be {MAX_NAME_LENGTH} characters or fewer, "
735 | …, and must not start or end with a hyphen or contain consecutive
hyphens."
|
^^^^^^^^^^^^^^^^^
736 | …
|

Found 1 error.

[Copilot]

@copilot fix the failed check:

FAILED: lint in packages/core
...

Fixed in 73bb51b — split the long string literal across two lines to stay within the 120-character limit.