# Tasks: enterprise-gaming-ik-solver

## 0. Pre-flight (non-negotiable)

- [ ] 0.1 Confirm clean working tree (`git status` reports nothing) and no in-flight worktrees with uncommitted work (`git worktree list` then `git status` in each)
- [ ] 0.2 If any worktrees exist under `.claude/worktrees/`, account for each one: still-active agent, work-pending-merge, or stale-and-prune. Stale worktrees MUST be removed (`git worktree remove`) before opening a new one — code that has been lost twice on main is the failure mode this guards against.
- [ ] 0.3 Confirm the package set in `MANIFEST.md` matches `find packages -maxdepth 3 -name package.json` count. Drift here means a prior change archived without regenerating the manifest.

## Phase 1 — Scaffold

- [ ] Create `gaming/rigs/ik-solver/` (`@suaveplan/ik-solver`, `0.1.0`, `sideEffects: false`)
- [ ] `tsconfig.json`, `vitest.config.ts`

## Phase 2 — Error codes & constants

- [ ] `src/error-codes.ts` + `src/constants/index.ts` — `DEFAULT_MAX_ITERATIONS`, `DEFAULT_TOLERANCE`

## Phase 3 — Types

- [ ] `src/types/common.ts` + `common.md`

## Phase 4 — Vec3 math utils

- [ ] `src/utils/vec3-math.ts` — add/sub/scale/dot/cross/normalize/distance/lerp
- [ ] Tests + docs

## Phase 5 — Two-bone solver

- [ ] `src/solvers/two-bone/two-bone.ts` — law of cosines analytic solution + pole hint
- [ ] Tests (reachable/unreachable targets, degenerate chain)
- [ ] Docs

## Phase 6 — Look-at solver

- [ ] `src/solvers/look-at/look-at.ts` — quaternion from-to with up-vector and angle clamp
- [ ] Tests + docs

## Phase 7 — FABRIK solver

- [ ] `src/solvers/fabrik/fabrik.ts` — forward/backward pass, joint constraints, convergence check
- [ ] Tests + docs

## Phase 8 — Property tests

- [ ] `tests/property.test.ts` — two-bone reach, look-at alignment, FABRIK convergence

## Phase 9 — Pre-publish gate

- [ ] `bunx turbo lint typecheck test --filter=@suaveplan/ik-solver` green
- [ ] 100% coverage
- [ ] Publish: `bun scripts/publish.ts --package @suaveplan/ik-solver`