Add commit-trailers skill

Generated-by: Claude Opus 5.5

commit-trailers/SKILL.md

@@ -0,0 +1,45 @@
+---
+name: commit-trailers
+description: Commit message trailers for AI-assisted work — use when writing or reviewing a git commit message (or PR description) whose content was substantially generated by an AI tool; requires a `Generated-by: <Tool> <Version>` trailer per the ASF Generative Tooling Guidance.
+---
+
+# Commit trailers for AI-assisted work
+
+Commits in this workspace whose content was substantially generated by
+an AI tool must disclose the tooling in the commit message, per the
+[ASF Generative Tooling Guidance][gen-tooling]:
+
+```
+Generated-by: <Tool> <Version>
+```
+
+- Use this token whenever the content is substantially machine-generated
+  (not for a typo fix the human typed).
+- The ASF guidance also accepts the alternative form
+  `Co-authored-by: <Tool> <Version>`; `Generated-by:` is preferred here
+  for machine-parsable provenance.
+- The human commit author remains responsible for the contribution: the
+  contributor is responsible for disclosing material that is not their
+  original creation, and for ensuring the tool's terms grant rights
+  sufficient to license the output ([ICLA][icla], sections 4-5, 7-8).
+
+Precedent in this workspace: ocap-merkledag commit 68ffcca
+("Add high-level design doc for deploying on Cloudflare.").
+
+## Rationale
+
+The [Apache-2.0 license][apache2] and the [ICLA][icla] both require
+contributors to disclose material in a contribution that is not the
+contributor's original creation. Section 7 of the ICLA (third-party
+work) is not a practical route for AI output, because the source
+details are not knowable; a `Generated-by:` token in the commit
+message is the [ASF's recommended disclosure practice][gen-tooling],
+and keeps the record honest about what the signing contributor is and
+is not claiming to own. This tracks the U.S. Copyright Office's finding
+that purely machine-generated output is not copyrightable
+([Part 2: Copyrightability report][uspto-part2], 2025).
+
+[gen-tooling]: https://www.apache.org/legal/generative-tooling.html
+[icla]: https://www.apache.org/licenses/icla.pdf
+[apache2]: https://www.apache.org/licenses/LICENSE-2.0
+[uspto-part2]: https://www.copyright.gov/ai/Copyright-and-Artificial-Intelligence-Part-2-Copyrightability-Report.pdf