* fix(gateway): keep custom-skill rollback filesystem IO off the event loop
Closes#5747. Three blocking sites remained on the Gateway event loop in
the rollback route and its shared response reader, all offloaded through
asyncio.to_thread following the #5729 pattern:
- storage.validate_skill_markdown_content() creates a temp dir and writes
SKILL.md into it (site 1)
- the post-scan read of the file being replaced (site 2, named by #5729's
test docstring)
- _read_custom_skill_response(): load_skills() walks every skill directory
and read_custom_skill() opens SKILL.md — O(installed skills) loop time
paid per accepted rollback and per GET /skills/custom/{name} (site 3)
A blocking_io regression drives the full accepted-rollback path (past the
security scan) under the strict gate; the two pre-existing cases only
covered the pre-scan branches.
* fix(gateway): keep the skill element type in the response-parts closure
Review nit on #5751: tuple[object, ...] erased the element type for the
_skill_to_response call; Skill is already imported in this module.
* fix(skills): rollback reads its history off the event loop
rollback_custom_skill constructed the user-scoped storage, probed whether the
skill exists and parsed custom/.history/<name>.jsonl inline, while the sibling
get_custom_skill_history two lines above already offloads exactly those three
steps and documents them as "blocking filesystem IO that must stay off the
event loop". The history file grows one entry per edit carrying full previous
and new content, so a rollback request parsed the whole edit history on the
Gateway loop; the strict Blockbuster gate catches the construction as a blocking
os.getcwd() through SkillsConfig.get_skills_path() -> project_root().
Offload the three steps through the same worker-thread closure and anchor both
pre-scan branches under tests/blocking_io/.
* test(skills): address rollback anchor review feedback
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>