Conciseness

The body is lean and assumes competence — it never explains what Homebrew, SSH signing, or a linter is, and every section carries operational instructions rather than padding. It falls just short of the level-5 anchor because a few passages (the Step 7 bare-root paragraph and the portless CA aside) are dense run-ons that could be tightened without losing information.

Actionability

Nearly everything is copy-paste executable: `curl -fsSL https://bun.sh/install | bash -s "bun-v$(cat .bun-version)"`, the git-config table with per-setting check and apply commands, `bash scripts/setup.sh`, and the portless commands — and edge cases (no sudo, no network, non-macOS) each get concrete fallback commands. This matches the level-5 anchor; the `… true` ellipsis in the apply column is trivially resolved from the check column and does not create a real gap.

Workflow Clarity

Nine sequenced steps each embed verification (re-run `bun --version`, the three `gh` checks, `git config --global --list` confirmation, the three gates), with explicit failure handling ("If a gate fails, paste the shortest decisive lines into the table and keep going") and a mandatory final report. Clear sequence with explicit validation and error-recovery guidance matches the level-5 anchor.

Progressive Disclosure

No bundle files exist, and the body (~110 lines) keeps everything inline in SKILL.md; however it is well-sectioned and defers detail to real repo files one level deep ("Read `lefthook.yml` for what the hooks do", `scripts/setup.sh`, `wiki/conventions/devloop-urls.md`) instead of duplicating them. This fits the level-4 anchor (good structure, references clear, minor organization gaps); level 5 would require content appropriately split across files.

Specificity

The description enumerates concrete, specific capabilities — "Bun at the pinned version, the GitHub CLI and its auth, SSH commit signing and the recommended git config, workspace dependencies, lefthook hooks and the portless dev proxy — and verifying it with the type-check, lint and format gates" — with comprehensive coverage of the skill's scope. It matches the level-5 anchor (multiple specific concrete actions) and exceeds level 4, which allows minor coverage gaps.

Completeness

It opens with an explicit "Use when setting up or repairing a development environment..." clause and adds a second explicit trigger ("Also the place to start when bun, gh, turbo or a hook is missing or the wrong version"), so both what and when are answered concretely. This matches the level-5 anchor; level 4 would require the 'when' to be less explicit or specific.

Trigger Term Quality

It covers natural trigger phrasing users would actually say — "setting up or repairing a development environment" plus tool-name triggers "bun, gh, turbo or a hook is missing or the wrong version", including failure-state variations. Coverage is comprehensive including synonyms (set up / repair, missing / wrong version), fitting the level-5 anchor rather than level 4's "a few natural terms missing".

Distinctiveness Conflict Risk

It carves a clear niche — this repository's dev environment with named tools (bun, gh, turbo, lefthook, portless) — so it is unlikely to trigger for unrelated skills. Minimal conflict risk matches the level-5 anchor; level 4 would require minor overlap with closely related skills, which the tool-specific naming avoids.