Scope: Dental Floss, Picks & Tongue Cleaners (slug flosses) covers four product types — floss (string/tape/superfloss/threader), floss picks (disposable forks/reusable holders), interdental brushes, and tongue cleaners/scrapers. Excludes electric/water flossers (oral irrigators) — not in catalog.json as a sibling, and a different mechanism (powered water jet, not a hand tool); treated as out of scope for this leaf.

Seed: Equivalent of harvest date = interdental brush ISO size (0-8): almost never stated plainly to the buyer, decides whether the tool fits the gap at all, backfill from package color/number is unreliable since color-to-size mapping isn't standardized across brands. A ship's cook persona would notice first that floss picks and brush heads are single-use consumables bought in bulk counts, not durable goods — pack count and reorder cadence matter more than any one spec.

Sources:
[ada_floss] https://www.ada.org/resources/research/science-and-research-institute/oral-health-topics/floss — floss is nylon multifilament/PTFE monofilament, FDA Class I device, no waxed/unwaxed difference, implant-safe coated wire, 2019 Cochrane review on brush vs floss effectiveness — fetched excerpt, confirmed in curl'd HTML text
[wikipedia_dental_floss] https://en.wikipedia.org/wiki/Dental_floss — floss formats (string/tape/superfloss/threader), embrasure Types I/II/III table, floss pick Y/F shapes, holder types, history (silk to nylon) — fetched excerpt
[wikipedia_toothbrush_iso16409] https://en.wikipedia.org/wiki/Toothbrush (redirected from Interdental_brush) — ISO 16409 sizing 0-8, color/wire diameter not standardized — fetched excerpt
[wikipedia_tongue_cleaner] https://en.wikipedia.org/wiki/Tongue_cleaner — materials (plastic/metal/copper/historical), shapes (strap/rake/handle), VSC/halitosis mechanism — fetched excerpt

Branches: product_type routes to each type's own facet set (floss vs floss_pick vs interdental_brush vs tongue_cleaner), supported by wikipedia_dental_floss's four-way format table. embrasure_fit routes open_gap to interdental_brush_size and snug_contact to floss_format, supported by the Type I/II/III table in wikipedia_dental_floss plus ada_floss's note that brushes may outperform floss on open gaps. handling_preference routes handle_or_pick_preferred to floss_holder_type/floss_pick_shape, supported by wikipedia_dental_floss's note that holders suit gag-reflex/spacing cases.

Noise: exact mm passage-hole diameters per ISO size (e.g. size 0 ≤0.6mm) — left as ordinal size_0..size_8 values rather than a sourced numeric range, since only one source (Wikipedia) carried the table and the rule requires two sources per number; brush color codes — not standardized across brands per source, so not made a facet; silk floss biodegradability marketing claims — mentioned only as a material value, no separate facet; brand spec sheets (TePe, Colgate, Oral-B) — all blocked (403 or JS-only client-rendered pages) or not archived; proceeded on ADA + Wikipedia only, which between them cover the ISO standard, FDA classification, and every format/shape/material row found.

Corrections (2026-10-26):
- Added `interdental_brush_neck_angle` (straight_neck/angled_neck) and `interdental_brush_filament_softness` (standard_filament/extra_soft_filament) facets; sourced from tepe.com's Original/Angle/Extra Soft product-line pages (directly curl'd, confirmed product-group names "Idb Original" vs "Angle" vs "Idb Extra Soft" in the page's own data) plus, for the neck-angle axis, Wikipedia's Toothbrush article ("either supplied with a reusable angled plastic handle or an integral handle"). No second independent source found for filament softness within budget; TePe is the sole cited source for that facet, same as several existing single-sourced facets in this file (e.g. floss_coating_additive, tongue_cleaner_material).
- Added both new facets to the `interdental_brush` branch's `then_ask` and to the other three `product_type` branches' `makes_irrelevant`.
- Fixed `product_type`/`floss_pick` branch: added `floss_waxing` and `floss_coating_additive` to `then_ask` (pick-mounted floss carries the same wax/coating options as string floss).
- Fixed `embrasure_fit`/`open_gap`: added `floss_format` to `makes_irrelevant` for symmetry with the `snug_contact` leg.
- Fixed `handling_preference`/`finger_held_string`: added `floss_holder_type` and `floss_pick_shape` to `makes_irrelevant` for symmetry with the other leg.
- Corrected `floss_pick_shape.backfill_cost` from `low` to `medium`, matching `interdental_brush_shape`/`tongue_cleaner_shape`, since its own note already says many listings omit the shape.
- Added vocabulary entries for "Dental bridge" and "Braces," both already used in `floss_format`'s cold-start question and in two vocabulary `plain` texts.