The collision autopsy left two unrepaired defects, running in OPPOSITE
directions, and `outbound_collision_count` can only ever see one of them.
UNDER-COLLAPSE. Dedupe keys on `mlb:<personId>` when the participant is
proven and on the RAW PROVIDER SPELLING when it is not. Mickey Gasper
(681508) is on Boston's 40-man and not on its active roster, so an
active-only index could not identify him and every book's spelling of him
survived dedupe as its own proposition — retention was the first layer to
notice, far too late, and could only discard the loser.
SPLIT. The mirror image, and invisible to the collision metric because it
makes MORE identities, not fewer: Leo Jiménez (677870) is published as both
"Leo Jiménez" and "Leonardo Jimenez", so one human became two semantic
players in one game. Measured across the 15 MLB cohort slices since the
canonical-participant repair, this is a recurring class, not one case:
cam/cameron smith (5 slices), mitch/mitchell bratt, zac/zachary thornton,
leo/leonardo jimenez.
THE REPAIR READS MLB'S OWN RECORD. `hydrate=person` on the roster call the
pipeline already makes returns firstName / useName / useLastName, so the
legitimate name forms for a human come from the league rather than from an
alias table. An alias table is a list of the mistakes we happened to notice.
`nickName` is DELIBERATELY EXCLUDED: over 821 people it produced 14
ambiguous keys, because MLB's nickname field carries bare surnames and
shared clubhouse names — `nameKey('Smitty Smith')` is one string for both
Burch Smith and Will Smith. The four forms kept produce ZERO ambiguity.
Canonical participant reach widens to the 40-man; TEAM EVIDENCE still reads
the ACTIVE roster alone, so event admission and the impossible-binding
refusal are unchanged. Identity still fails closed: a name matching more
than one person in the event resolves to nobody.
CONTINUITY, MEASURED BEFORE WRITING ANY CODE. Over the real 19:00 cohort,
208 of 209 player_keys are unchanged and the one that moves is the defect —
`leonardo jimenez` converging onto `leo jimenez`, a key that already exists.
No new lineage family. The natural key contains game_date, so chains never
span dates and a forward change cannot fork a closed one.
DETERMINISTIC REPRESENTATIVE. Which book's payload survives was decided by
position. It is now decided by the existing MODEL_BOOKS declaration order —
reused, not authored; inventing a sportsbook ranking to settle a tiebreak
would be a market judgement smuggled in as a bug fix — with book name and a
content tiebreak. Stable under every input permutation.
TWO GUARDS, BOTH DIRECTIONS. split (one person, many identities) and merge
(one identity, many people). A merge is refused at the same single admission
seam event identity already uses; a split is counted and alerted but does not
cut the board, because it duplicates an identity rather than asserting a
falsehood.
RETENTION REMAINS AN INDEPENDENT CHECK. The old assertion grepped the source
for `player_key: nameKey(player)`. That expression stood in for a PROPERTY,
and a grep verifies a spelling. Replaced with the property itself, asserted
in both modes: when the producer emits two rows for one human, retention
still files them under one identity and still reports the collision.
Replay of the real cohort through the repair: 3,129 offerings, 100%
participants resolved, every one of 207 participants on exactly ONE semantic
key, collision 0, split 0, merge 0.
Suite 396/5,455/0 · tsc 0 · 15/15 teeth. Tooth 12 came back green first
time and that was a coverage hole, not a safe defect: nothing asserted
retention's append-only upsert. It does now.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CQJeAG8vcDoL5zkiaJyVb8
