@startuml bv-survivorship-rules
!pragma layout smetana
title Survivorship — Field ranks, null policies, and delta semantics
skinparam backgroundColor #fafbfc
skinparam defaultFontName SansSerif
skinparam shadowing false
skinparam ArrowColor #5a6a7e
skinparam rectangle {
  FontSize 12
  BorderThickness 1
}
skinparam package {
  FontSize 13
  BorderColor #4a5568
  BackgroundColor #ffffff
}

left to right direction

package "Incoming Satellite History" as Inputs #edf0f4 {
  rectangle "sat_person_kafka\nRank = 1\nNull policy: inherit\nMode: delta" as InKaf #e7f6ed
  rectangle "sat_person_oracle\nRank = 2\nNull policy: apply\nMode: full" as InOra #e8f0fb
  rectangle "sat_person_seed\nRank = 3\nOperation: seed\nMode: seed" as InSeed #fff6e8
}

package "SurvivorshipMerge Transform" as Logic #ffffff {
  rectangle "Rank Arbitration\nRank 1 wins over Rank 2\n(Ranks can disagree per column!)" as Ranks #f3ebfb
  rectangle "Null Policy: inherit vs apply\ninherit: skip null & keep prior value\napply: write null & clear attribute" as Nulls #fff6e8
  rectangle "Present Flags (Sparse Feeds)\nflag = 'N': field omitted (keep value)\nflag = 'Y': explicitly cleared (apply null)" as Flags #edf0f4
  rectangle "Leg Operations\nupsert: standard update\nseed: fills gaps, never overwrites upsert\ndelete: withdraws source contribution" as Ops #e8f0fb
}

package "Consolidated SCD2 Attribute State" as Out #f3ebfb {
  rectangle "Surviving Target Row\nKafka email wins (Rank 1)\nOracle city preserved when Kafka sends null\nEmitted ONLY when surviving state changes" as Emit #e7f6ed
}

InKaf --> Ranks
InOra --> Ranks
InSeed --> Ops
Ranks --> Nulls
Nulls --> Flags
Flags --> Ops
Ops --> Emit
@enduml