playground/                          # real, all bytes — grows only when something exists
├─ engine                            # THE ENGINE: seat×court loop — press → seat patch → hatch → press → click ⟹ adopt
├─ physics/
│   ├─ engine                        # the court, executable zsh+jq: validate·coverage·compile·contact·diff·press·click·mint·ledger
│   ├─ physics.spec.yaml             # the 15-organ design the court grows toward
│   └─ PHYSICS.sha                   # md5 of court — the world-version
├─ bundles/
│   ├─ seatmove/                     # resident — sha 238e0217d3d16ce5, lineage genesis → bcc8931b → cd4e3c8f; c-03 seat-written
│   │   ├─ head.json names.json claims.json derive.json
│   │   └─ scenarios/ s-001..s-003   # s-003 minted from residue/r-001 (live-door red)
│   ├─ rebook/                       # the real program — sha 35d3d6cb122e9368: 8 claims · 2 derive · 6 scenarios (incl. curveball turn)
│   │   ├─ world.md                  # the policy prose the claims cite (origin fragments)
│   │   ├─ head.json names.json claims.json derive.json
│   │   └─ scenarios/ s-001..s-006
│   └─ tau-retail/                   # THE MOUNTAIN: tau-bench retail, vendored 2026-08-26 (PROVENANCE.md)
│       ├─ world.md                  # their policy wiki, verbatim — the claims' origin
│       ├─ world/db/                 # their mock DB: users 500 · orders 1000 · products 50
│       └─ specimens/                # their 16 tools + tasks_test.py — reference only, never executed
├─ candidates/
│   ├─ seatmove-h1/                  # the hatch that clicked and was adopted (round 1)
│   └─ seatmove-lobo-thin/           # his literal ablation — clicked b35723812a544981: thinner scenario set, worse program survives
├─ graveyard/
│   └─ seatmove-lobo/                # first corpse: c-01 cut, scenarios kept — false-clicked under v0, never-was under coverage
├─ residue/r-001.json                # the door's red as caught, pre-mint — the import channel is open
├─ traces/                           # immutable contact traces, per bundle
├─ ledger/LEDGER.jsonl               # append-only: genesis · contacts · deltas · residue · dead_scenario · mint · hatch · adopt · sha/physics transitions
└─ craft/schemas/bundle.schema.yaml  # the language (JSON Schema 2020-12)

# absent until bytes exist: seats/ carriers/ craft/{examples,presses}
# usage: engine seatmove              (SEAT_MODEL/ENGINE_MODEL, default sonnet; ROUNDS=4)
#        physics/engine press|mint <bundle> [file]