scaffold-cost-check

# Scaffold Cost Check Measure the token cost of Mycelium's stable scaffolding — the context surface loaded at SessionStart and on routine canvas/memory reads — so claims about "negligible overhead" are auditable. Datadog's *State of AI Engineering* (2026) reports ~69% of input tokens across production agents are system prompts; this skill makes Mycelium's analogous number visible. ## When to Use - First-time audit on a project to compare actual scaffold cost against any "~6K negligible" claim in landscape/positioning. - Periodic refresh via `/mycelium:framework-health` (see Wiring below). - Before adding a new canvas file or harness doc that joins the stable load surface, to surface the marginal cost. ## Preflight: Read target canvas file(s) before any Write/Edit Hard rule. Before issuing `Write` or `Edit` against any `.claude/canvas/*.yml`, use the **Read tool** on that file in this session. This skill only WRITES if explicitly asked to persist its output to `dora-metrics.yml#apex.scaffold_token_estimate`; default behavior is print-only. ## Workflow 1. **Inventory the stable scaffold surfaces** in the current project's plugin cache (or fall back to `.claude/` for legacy installs): - `CLAUDE.md` (project-local; the dispatcher) - `${CLAUDE_PLUGIN_ROOT}/engine/` (all `.md` and `.yml`) - `${CLAUDE_PLUGIN_ROOT}/harness/` (all `.md`) - `AGENTS.md` (project-local, if present — the router for non-Claude-Code runtimes; **not** a plugin file. It lives at a repo root...