VYNDR had three definitions of "same player": raw p.player (dedupe),
utils/normalize.normalizeName (features, NO nicknames), utils/playerName.nameKey
(retention, WITH nicknames). Retention was the first layer to notice they
disagreed, and all it could do was discard the loser — 28 collisions.
The fix is not a better spelling. The event-scoped roster ALREADY carries the
StatsAPI personId; buildPlayerTeamIndex was fetching and discarding it.
SCOPE IS LOAD-BEARING, and this is the finding that shaped the design. Measured
on the real 2026-08-28 league rosters (1,583 rows, 30 teams): a bare name key is
NOT globally unique — `max muncy` (ATH 691777 / LAD 571970), `jose fermin`
(665877/820862) and `luis garcia` (472610/671277) each resolve to TWO different
humans. Team-scoped: 0 ambiguous. Event-scoped across 33 real events including
the verified doubleheader date: 0 ambiguous. So resolution is scoped to the two
teams actually playing, and FAILS CLOSED — no event, no game, no candidate, or
more than one candidate yields null and the prop keeps prior behaviour.
FEATURE IDENTITY PARITY, measured on both real cohorts before writing the patch
(504 participants):
RAW_SUCCESS/CANONICAL_SUCCESS/SAME id 365
RAW_SUCCESS/CANONICAL_SUCCESS/DIFFERENT id 0 <- required 0
RAW_SUCCESS/CANONICAL_FAIL 0 <- required 0
CANONICAL_AMBIGUOUS 0 <- required 0
RAW_FAIL/CANONICAL_SUCCESS 7 <- repair, not regression
The seven improvements are exactly the alias class: Michael->Mickey Gasper,
AJ->A.J. Ewing, JT->J.T. Realmuto, Mike->Michael Busch, Richard->Richie
Palacios. This is why raw spelling could not be trusted: player_id_map holds
`mickey gasper` and NOT `michael gasper`, so under the raw name the lookup
outcome depended on which alias happened to survive dedupe. Provider arrival
order was deciding model input availability.
ALL SEVEN COLLISION GROUPS PROVEN SAME_PLAYER_ALIAS against the authoritative
roster for the exact event date — one personId each (681715, 699625, 676356,
695491, 673357, 681508, 671739), zero false normalizations, zero unresolved —
and all seven collapse to one participant under the new key, so the 14 colliding
propositions merge upstream instead of being discarded downstream.
FALSE-MERGE SIMULATION on both cohorts: cross-event 0, different-stat 0,
different-line 0, false merges 0. Note honestly: the retained rows cannot
exhibit the merges themselves, because retention already discarded the losers —
so the merge half is proven directly on the alias groups, the safety half on the
cohorts.
RETENTION IS UNTOUCHED — schema, player_key, conflict identity and the collision
counter are all unchanged. collision_count must reach 0 by upstream repair, never
by making the counter lenient. A teeth proof injects raw spelling into the
retention identity and the suite rejects it.
Source provenance preserved: p.player is never overwritten; the participant
rides beside it as mlb_person_id + canonical_player_name.
Twelve teeth against a green baseline of 117 — dedupe back to raw name (3),
feature lookup back to the alias (2), resolver stops blocking ambiguity (1),
lookup degraded to raw (1), event scope dropped (1), event/line/stat dropped
from the key (2/2/2), provenance destroyed (1), raw spelling in retention
identity (2), collision_count accepted nonzero (2), and a guard proving the
frozen game-date repair cannot be reverted (10). Restored byte-identically.
Teeth #4 (canonical resolving to a DIFFERENT feature id) is covered by the
real-data parity measurement rather than an injected branch, because it is a
data comparison, not a code path — stated plainly rather than claimed as a test.
No hardcoded player names in production code — a test greps for all seven.
4 files, 86 insertions. retentionService, gameBinder, oddsService,
acquisitionTrace, probabilityEstimator, bookRoles, playerName, normalize and
snapshotScheduler: UNCHANGED. Admission rules, MODEL_BOOK filters and model
formulas: 0 changed lines. The game-date repair is intact.
391 suites / 5,339 tests pass. web tsc exit 0. Lineage stays OFF.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CQJeAG8vcDoL5zkiaJyVb8
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