diff --git a/LESSONS.md b/LESSONS.md
index 1eef110..0b4990a 100644
--- a/LESSONS.md
+++ b/LESSONS.md
@@ -122,6 +122,10 @@ A skill-audit run by a fresh agent (no conversation context) caught 2 FAILs that
 
 Two forks independently fixed `references/sources.md` with different approaches — one added a header comment, the other replaced the paths with relative references. Both were plausible; neither read the spec first. Reconciling required a third fork to read the authoritative source and revert to the correct format (repo-root-relative, per skill-author Step 5). Fix: when multiple forks are in scope for the same file, either (a) scope them to non-overlapping files explicitly, or (b) sequence them rather than parallelise. If a fix is spec-governed, always read the spec before applying it — the "obvious" fix is wrong as often as it is right.
 
+## 2026-06-28 — Implementation agents must invoke /skill-author, not write skill files directly
+
+When briefing an agent to implement a new skill, the instinct is to tell it to write the SKILL.md and supporting files directly. This bypasses Step 5 of the skill-author process (provenance), which requires reading all research `sources.md` files and recording every `extracted` slug in META.md. The `validate-provenance.sh` script catches the gap — but only after the commit, requiring a fix round. This pattern recurred twice in one session (plugin-author and marketplace-author initial implementation, then again in the first round of fix agents). Fix: briefs for implementation agents must explicitly say "invoke `/skill-author` (read and follow `plugins/kyberforge/skills/skill-author/SKILL.md`)" — not "write the skill files." Invoking the skill is the only reliable way to ensure all process gates, including provenance, run.
+
 ## 2026-05-18 — Planning meta-commentary does not belong in deployed artifacts
 
 During write-skill refactor, an "open thread" note (about a deferred research step) was written directly into the SKILL.md Process section. The user caught it. The rule it violated: a deployed artifact (SKILL.md, a runtime file loaded by agents) must not contain planning meta-commentary — deferred items, open threads, and implementation notes belong in the issue file, which is the planning artifact. The skill body should contain only content relevant to runtime execution. If a decision is deferred, record it in the issue and leave no trace in the skill. The distinction: issue = planning record; skill = executable instruction.