Why: roles had no way to carry operational know-how into executions
(RoleSpec.Skills never reached the backend), and the system prompt was
assembled ad hoc with no environment facts or skill index.
Evidence: go vet ./... clean; go test ./... 12 packages ok. Skills
cases cover directory-authoritative naming, optional frontmatter
description extraction, invalid dir skipping, root priority on name
clash, missing-root tolerance, fail-closed unknown-skill loads, 64 KiB
body / 200-byte description caps, load_skill registration only when
skills exist, and end-to-end adapter wiring (index in system prompt,
declared-skill validation failing closed on ghost skills, workspace
.agent/skills auto-merge). promptx cases pin section order, sorted
index, reasoning-profile sentence, and env defaults.
Impact: new runtime/skills + runtime/promptx packages; native.Options
gains SkillsRoots; adapters/native system prompt now composes
instructions + environment (date/model/workspace/profile) + declared
skills + index + deliverables; declared-but-missing skills fail the
step (configuration error, not silent).
Refs: plan B6; RoleSpec.Skills plumbing lands with the squad batch.
weichen
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