Scope: classic non-electronic, non-licensed play toys for infants through young children, bundled by product type — infant sensory toys (rattles, teethers), stacking & sorting toys (rings, nesting cups, shape sorters), push/pull & mechanism toys (wagons, pull-alongs, corn poppers, jack-in-the-boxes, wind-ups), and spin & skill toys (yo-yos, spinning tops). Excludes sibling leaves below.

Seed:
1. Equivalent of the knife-hardness example: axle type on a yo-yo (fixed vs ball-bearing) is one side of a trade-off — sleep time and trick range vs automatic, beginner-friendly return.
2. A nurse would notice the choking-hazard age labeling and cord/string lengths first — whether a toy with small detachable pieces or a pull cord is actually safe for the under-3 the listing claims it suits, before caring about material finish.

Sources:
[wikipedia_toy_safety] https://en.wikipedia.org/wiki/Toy_safety — ASTM F963, EN 71-6 age-warning symbol, CPSIA lead/phthalate limits ages 12 and under, small-parts choking-hazard warning for under-3 — fetched excerpt
[wikipedia_teether] https://en.wikipedia.org/wiki/Teether — silicone/wood/rubber materials, teething-jewelry choking recalls — fetched excerpt
[wikipedia_baby_rattle] https://en.wikipedia.org/wiki/Baby_rattle — wood/plastic/cloth materials, internal-fill sound mechanism, hand-eye coordination purpose — fetched excerpt
[wikipedia_yoyo] https://en.wikipedia.org/wiki/Yo-yo — fixed axle vs ball-bearing axle, responsive vs unresponsive string + bind, sleep-time figures — fetched excerpt
[wikipedia_spinning_top] https://en.wikipedia.org/wiki/Spinning_top — finger-twirl, string-pull, mechanical-launcher mechanisms; tip material and moment of inertia drive spin duration — fetched excerpt
[wikipedia_fine_motor] https://en.wikipedia.org/wiki/Fine_motor_skill — pincer grasp develops 7-12 months, hand-eye coordination 2-5 months — fetched excerpt
[wikipedia_montessori_sensorial] https://en.wikipedia.org/wiki/Montessori_sensorial_materials — graded-size stacking (Pink Tower), "control of error" self-correcting design — fetched excerpt
[wikipedia_radio_flyer] https://en.wikipedia.org/wiki/Radio_Flyer — wagon body material evolution wood to stamped steel to plastic — fetched excerpt
[wikipedia_jackinthebox] https://en.wikipedia.org/wiki/Jack-in-the-box — crank/music-box mechanism, cause-and-effect purpose — fetched excerpt

Branches:
- toy_type -> infant_sensory: "fetched excerpt" lines for rattle/teether sources route to sensory_toy_subtype, mouthable_material_safety.
- toy_type -> stacking_sorting: Montessori sensorial + fine-motor sources route to sorting_mechanism, piece_count_bucket.
- toy_type -> push_pull_mechanism: Radio Flyer + Jack-in-the-box sources route to body_material, motion_feedback.
- toy_type -> spin_skill: Yo-yo + Spinning top sources route to axle_or_spin_mechanism, string_response_type, skill_level.
- child_age_stage -> under_12_months: makes irrelevant skill_level and small-piece stacking facets per the under-3 small-parts warning in wikipedia_toy_safety.

Noise (spec-sheet rows left out, with reason):
- Price/brand/rating: never facets per rule.
- Battery/electronic sound chips: excluded — portable_electronic_games is the sibling leaf for battery-powered play.
- Combat/battle spinning tops (e.g. launcher-vs-launcher battle play): excluded — battle_tops is its own sibling leaf.
- Interlocking construction pieces (bricks, magnetic tiles): excluded — building_blocks is its own sibling leaf.
- Figures, plush, dollhouses, bath toys, beach/sand toys, play dough, marble runs, kites/gliders, game timers, ball pits: each is its own sibling leaf; not duplicated here.
- Exact pull-cord length threshold (inches) and small-parts test cylinder dimensions: no second numeric source found this run (CPSC.gov blocked bot access, AAP/healthychildren.org page moved, archive.org rate-limited); kept as categorical facets citing the general warning rather than inventing a number.

Corrections (2026-10-26):
- safety_standard_compliance and choking_hazard_small_parts_warning: source changed listing -> researched; both facets' own listing_field_hint already said the data is rarely/inconsistently on retail listings.
- toy_type branches (all four): then_ask completed to each type's full facet set and makes_irrelevant completed to clear every facet exclusive to the other three types.
- Added facet yo_yo_body_shape (imperial_round/butterfly/unspecified), cited to wikipedia_yoyo's butterfly-shape text and a fetched Duncan Toys "Imperial" yo-yo product page (new reference duncan_imperial_yoyo); added to the spin_skill branch's then_ask.
- piece_count_bucket: evidence (wikipedia_montessori_sensorial, wikipedia_fine_motor) removed since neither source states the 3-5/6-10/10+ cutoffs; added a judgements entry flagging the bands as editorial, not cited.
- Added vocabulary entry for "Transaxle" (modern yo-yo axle/bearing design, from wikipedia_yoyo).
- Vocabulary entry "Pincer grasp" re-tagged from facet piece_count_bucket to child_age_stage, which already cites the source (wikipedia_fine_motor) the term comes from.