implement-spec

# Implement Spec Build the active spec to completion, one reviewable pass at a time. The spec is the source of truth, but the architecture is allowed to improve when the code teaches you the plan is stale. A pass (usually one slice) is a **commit checkpoint, not a stopping point.** The job is the whole spec — every slice, every global TODO — not the first green commit. Finishing a pass means starting the next one, not handing back to the user. Only stop when the spec is fully implemented (or a genuine blocker needs a decision only the user can make). **Work in parallel wherever the graph allows.** Do not walk the ladder one slice at a time when slices are independent. Read the spec's dependency graph as a wavefront and **delegate independent passes to subagents that run concurrently** (see Rules) — you orchestrate and integrate; only serialize what genuinely depends on prior work. ## Workflow 1. Read the repo README, the spec README, and the next slice before editing. Load any skills named by the spec. Identify the current pickup point, global TODOs, required gates, and what must stay green. If a multi-slice spec lacks a live handoff prompt, add one before the first pass ends. 2. Reconcile the plan with the current code. If the slice would preserve a development-only shim, duplicated type, weak wrapper, or obsolete path, replace it with the simpler architecture and update the spec handoff. 3. Implement one coherent pass: usually one slice, one vertical che...