206fd1ec35
Found while adding pi-devbox-firstboot, whose description was drafted at 1056 characters against pi's MAX_DESCRIPTION_LENGTH of 1024. pi does not reject it: dist/core/skills.js pushes a diagnostic and then loads the skill anyway -- "Still load the skill even with warnings, unless description is missing or empty". So the skill works, the violation is real, and the only thing that would ever report it is a diagnostic inside a live pi session. Nothing in CI starts one, so the warning is invisible here by construction. A spec violation that still works is the most durable kind of rot: nothing forces the fix. Unlike check-skill-floor.sh, this was NOT free to add. Measured headroom on the five baked skills: credential-incident-response 1022 (2 chars spare), pi-extensions 1003 (21), pi-devbox-firstboot 952, pi-devbox-environment 923, mempalace 254. Two of five are within one sentence of the limit, so "nobody would write a description that long" is already false here. It also catches the sibling failure that is a silent DROP rather than a warning: a missing or empty description returns skill: null, so the file ships, the symlink resolves, smoke-test's `test -f` passes, pi-devbox-version lists it -- and no agent can ever see it. Name rules are checked too, including against the directory, because the loader falls back to parentDirName and a mismatch silently renames the skill while every path-based pointer (the managed AGENTS block included) keeps naming the directory. Truth table, each mutation verified to differ materially from the shipped tree: shipped 0; over-long description 1; missing description 1 (reported as fatal, not a mere violation); name != directory 1; no frontmatter 1; directory with no SKILL.md 1; absent skills tree 2. Exit codes match lint-shell.sh, check-skill-floor.sh and check-doc-drift.sh -- a gate that cannot run must not pass. python3-yaml rather than grep/awk because `description: >-` is a folded block scalar whose value spans lines and joins with spaces, so a line-oriented length check measures the wrong string. Same package the actionlint job already installs, same parser check-doc-drift.sh already uses. The vendored copies (pi-extensions, mempalace) are deliberately in scope: an upstream edit over the limit turns this red on a file this repo does not author, which is precedented by check-skill-floor.sh's coupling and correct because the image ships those bytes. The fix in that case is to refresh the snapshot, not to exempt the file.