GEN-1: add Probeverpaarung API (breed) + public index

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

gerbil-manager-web/src/genetics/breed.ts

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+/**
+ * Probeverpaarung (test mating): predict offspring of two parent genotypes.
+ *
+ * Pipeline: Punnett combine -> merge identical genotypes -> apply lethality
+ * (remove SpSp, renormalise, collect warnings) -> annotate each surviving
+ * genotype with its Farbschlag and probability. Also aggregates by Farbschlag.
+ *
+ * Pure & deterministic; no React, no I/O. Display texts (warning messages) are
+ * resolved from CODES in the UI layer (de.ts).
+ */
+import { add, toNumber, toPercentString, toString, ZERO, type Fraction } from './fraction'
+import { type Genotype, toDisplayString, toJSON } from './genotype'
+import { combineGenotypes, mergeByGenotype } from './punnett'
+import { applyLethality } from './lethality'
+import { farbschlagFor } from './catalog'
+import type { GeneticsWarning } from './warnings'
+import type { LocusKey } from './loci'
+
+export interface Probability {
+  readonly fraction: Fraction
+  /** Decimal in [0,1]. */
+  readonly value: number
+  /** "3/16" style. */
+  readonly text: string
+  /** "18.75 %" style. */
+  readonly percent: string
+}
+
+function prob(f: Fraction): Probability {
+  return { fraction: f, value: toNumber(f), text: toString(f), percent: toPercentString(f) }
+}
+
+export interface OffspringGenotype {
+  readonly farbschlag: string
+  /** Compact display string, e.g. "Aa CC Dd EE GG Pp spsp rere". */
+  readonly genotype: string
+  /** Structured genotype (JSON storage shape). */
+  readonly genotypeJson: Record<LocusKey, [string, string]>
+  readonly probability: Probability
+  /** True when the Farbschlag could not be named from the catalog. */
+  readonly unknownFarbschlag: boolean
+}
+
+export interface FarbschlagShare {
+  readonly farbschlag: string
+  readonly probability: Probability
+}
+
+export interface BreedingResult {
+  /** Per-genotype offspring distribution (live births), highest probability first. */
+  readonly offspring: OffspringGenotype[]
+  /** Aggregated by Farbschlag (colour-morph), highest probability first. */
+  readonly byFarbschlag: FarbschlagShare[]
+  readonly warnings: GeneticsWarning[]
+}
+
+function byProbDesc<T extends { probability: Probability }>(a: T, b: T): number {
+  return b.probability.value - a.probability.value
+}
+
+/** Predict the offspring distribution of father × mother. */
+export function breed(father: Genotype, mother: Genotype): BreedingResult {
+  const raw = combineGenotypes(father, mother)
+  const merged = mergeByGenotype(raw)
+  const { distribution, warnings } = applyLethality(merged)
+
+  const offspring: OffspringGenotype[] = distribution
+    .map((entry) => {
+      const match = farbschlagFor(entry.value)
+      return {
+        farbschlag: match.name,
+        genotype: toDisplayString(entry.value),
+        genotypeJson: toJSON(entry.value),
+        probability: prob(entry.probability),
+        unknownFarbschlag: match.unknown,
+      }
+    })
+    .sort(byProbDesc)
+
+  const colorMass = new Map<string, Fraction>()
+  for (const entry of distribution) {
+    const name = farbschlagFor(entry.value).name
+    colorMass.set(name, add(colorMass.get(name) ?? ZERO, entry.probability))
+  }
+  const byFarbschlag: FarbschlagShare[] = Array.from(colorMass.entries())
+    .map(([farbschlag, f]) => ({ farbschlag, probability: prob(f) }))
+    .sort(byProbDesc)
+
+  return { offspring, byFarbschlag, warnings }
+}

gerbil-manager-web/src/genetics/index.ts

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+/**
+ * Gerbil colour-genetics engine — public API.
+ *
+ * Pure TypeScript domain module (no React, no API calls). The UI layer (FEAT-5)
+ * consumes `breed()` and resolves warning CODES to German text via de.ts.
+ */
+export { breed } from './breed'
+export type {
+  BreedingResult,
+  OffspringGenotype,
+  FarbschlagShare,
+  Probability,
+} from './breed'
+
+export {
+  makeGenotype,
+  wildType,
+  toDisplayString,
+  fromDisplayString,
+  toJSON,
+  fromJSON,
+  hasUnknown,
+  WILDCARD,
+} from './genotype'
+export type { Genotype, AllelePair } from './genotype'
+
+export { LOCI, LOCUS_ORDER } from './loci'
+export type { LocusKey, LocusDef } from './loci'
+
+export { phenotypeTokens } from './phenotype'
+export type { PhenotypeTokens } from './phenotype'
+
+export { farbschlagFor, BASE_COLORS, CATALOG_SIZE, UNKNOWN_FARBSCHLAG } from './catalog'
+export type { FarbschlagEntry, FarbschlagMatch } from './catalog'
+
+export { GeneticsWarningCode } from './warnings'
+export type { GeneticsWarning } from './warnings'
+
+export type { Fraction } from './fraction'