REVIEW-FIXES-BACKEND: CR-9 + CR-11 + CR-10 + DB-1

CR-9 (major): gidByNameDob TryGetValue + ExternalRef-Fallback
  Verhindert KeyNotFoundException wenn Name/DOB zwischen zwei Laeufen driftet
  (z.B. correctDob-Remap oder UI-Umbenennung). Fallback: ExternalRef-Dict-Lookup;
  bei Miss: sauberes Ueberspringen + Note statt 500. +Test CR9_NameDOB_drift.

CR-11 (major): Farbschlag aus Genotyp ableiten (fill-NULL-only)
  Deep-Band-Tiere (gen>=2, kein Farbschlag-Feld) landen nicht laenger mit null
  ColorVariety. GenotypePotentiallyMatches() vergleicht locus-pair-weise (??=wildcard,
  case-insensitive). Nur vollstaendige Genotypen (8 Loci, kein ??) loesen Ableitung aus.
  Plan-Loop: fuellt colorVarietyId bei null + vollstaendigem Genotyp.
  Post-Sweep: bestehende DB-Tiere mit null ColorVarietyId werden nachgefuellt.
  AnimalSummary.FarbschlagDerivedFromGenotype = Zaehler. +Test CR11_ColorVariety_from_geno.

CR-10 (major, Python): malformed Override-Genotyp wird nicht angewendet
  apply_conflict_decisions validiert mapped8locus nach gt.parse(). Leeres Ergebnis
  = Genotyp unveraendert + decisionWarning statt stillem Blanken. Konflikt wird
  trotzdem aufgeloest (Entscheidung gilt, nur Genotyp-Override ausgelassen).
  +5 Python-Tests (CR-10-Block in test_extract.py).

DB-1 (high): filtered unique index auf Gerbil.ExternalRef
  WHERE ExternalRef IS NOT NULL — verhindert doppelten Import bei Race-Conditions
  oder Lauf-Ueberschneidungen. Migration UniqueExternalRef. SQLite-Testhost:
  HasFilter() wird via EnsureCreated appliziert (SQLite unterstuetzt Partial-Indexes).
  PartialUpdateTests externalRef-Assertion auf NotNull geaendert (name-hash unique).

GATE: 139/139 C# + Python ALL PASS, ef has-pending=No.

GerbilManagerWebAPI/ApplicationContext.cs

@@ -81,6 +81,12 @@ public class ApplicationContext : DbContext
                 .HasForeignKey(g => g.EnclosureId).OnDelete(DeleteBehavior.SetNull);
             e.HasOne(g => g.ColorVariety).WithMany()
                 .HasForeignKey(g => g.ColorVarietyId).OnDelete(DeleteBehavior.SetNull);
+
+            // DB-1: ExternalRef is the import idempotency key — enforce uniqueness at the DB level.
+            // Filtered (nulls allowed: manually-entered animals have no ExternalRef).
+            e.HasIndex(g => g.ExternalRef)
+                .IsUnique()
+                .HasFilter("\"ExternalRef\" IS NOT NULL");
         });
 
         modelBuilder.Entity<Litter>(e =>

GerbilManagerWebAPI/Import/ImportModels.cs

@@ -102,7 +102,8 @@ namespace GerbilManagerWebAPI.Import
         int AlreadyImported,
         QuarantineSummary Quarantined,
         int ParentLinksFromChart = 0,
-        int ConflictsResolvedByDecision = 0);
+        int ConflictsResolvedByDecision = 0,
+        int FarbschlagDerivedFromGenotype = 0);
 
     public sealed record QuarantineSummary(
         int Conflicts,

GerbilManagerWebAPI/Import/ImportService.cs

@@ -145,25 +145,63 @@ namespace GerbilManagerWebAPI.Import
                 .ToDictionary(g => g.ExternalRef!, g => g.LitterId);
             var existingColorVarietyByExtRef = existingRows.Where(g => g.ExternalRef != null)
                 .ToDictionary(g => g.ExternalRef!, g => g.ColorVarietyId);
+            // CR-9: ExternalRef → Gerbil.Id fallback for name/DOB drift on re-import
+            var existingGidByExtRef = existingRows.Where(g => g.ExternalRef != null)
+                .ToDictionary(g => g.ExternalRef!, g => g.Id);
+
+            // CR-11: load CanonicalGenotype for genotype-derived Farbschlag matching
+            var varietiesWithGeno = await _db.ColorVarieties
+                .Select(v => new { v.Id, v.Name, v.CanonicalGenotype }).ToListAsync();
 
             // PASS 1: assign ids + resolve fb/gender/Wurfchronik link (no writes yet).
             var plan = new List<AnimalPlan>();
+            int fbDerivedFromGenotype = 0;
             foreach (var a in loadable)
             {
                 bool exists = existingGerbilSet.Contains(a.Id);
-                var gid = exists ? gidByNameDob[NameDobKey(a.Name, ParseDate(a.Dob))] : Guid.NewGuid();
+                // CR-9: use TryGetValue; fall back to ExternalRef lookup for name/DOB drift
+                // (e.g. correctDob remap or manual rename). Prevents throwing KeyNotFoundException.
+                Guid gid;
+                if (exists)
+                {
+                    if (!gidByNameDob.TryGetValue(NameDobKey(a.Name, ParseDate(a.Dob)), out gid))
+                    {
+                        if (existingGidByExtRef.TryGetValue(a.Id, out gid))
+                            notes.Add($"Hinweis: '{a.Name}' (*{a.Dob}) per ExternalRef gefunden trotz Name/DOB-Drift (correctDob oder UI-Umbenennung).");
+                        else
+                        {
+                            notes.Add($"Warnung: ExternalRef '{a.Id}' in DB vorhanden aber nicht auflösbar — Tier übersprungen.");
+                            continue;
+                        }
+                    }
+                }
+                else gid = Guid.NewGuid();
 
                 Guid? wurfLitterId = null;
                 if (a.LitterRef?.Confidence == "hoch" && a.LitterRef.Candidates is not { Count: > 0 }
                     && litterIdMap.TryGetValue(a.LitterRef.LitterId, out var lid))
                     wurfLitterId = lid;
 
+                // CR-11: Farbschlag from explicit name-match first; fall back to genotype derivation
+                // (fill-NULL-only — never overwrites an explicit name-match or manual assignment).
                 Guid? colorVarietyId = null;
                 var fbCandidates = new[] { a.Farbschlag }.Concat(a.FarbschlagVariants)
                     .Where(s => !string.IsNullOrWhiteSpace(s));
                 foreach (var fb in fbCandidates)
                     if (varietyByName.TryGetValue(fb.Trim().ToLowerInvariant(), out var vid))
                     { colorVarietyId = vid; break; }
+                if (colorVarietyId is null && a.Genotype.Mapped8locus.Count >= 8)
+                {
+                    // CR-11: only derive from a fully-specified genotype (all 8 loci known,
+                    // no "??" wildcards). Partial genotypes (single-locus or sparse records)
+                    // would match any catalog entry via wildcards and produce false positives.
+                    var composed = ComposeGenotype(a.Genotype);
+                    if (!composed.Contains("??"))
+                        foreach (var v in varietiesWithGeno)
+                            if (!string.IsNullOrWhiteSpace(v.CanonicalGenotype)
+                                && GenotypePotentiallyMatches(composed, v.CanonicalGenotype))
+                            { colorVarietyId = v.Id; fbDerivedFromGenotype++; break; }
+                }
 
                 var gender = InferGender(a, sireNames, damNames);
                 var norm = Normalize(StripZucht(a.Name));
@@ -469,6 +507,33 @@ namespace GerbilManagerWebAPI.Import
             int farbschlagWouldRebackfill = plan.Count(p =>
                 p.Exists && p.ColorVarietyId is not null && p.ColorVarietyId != p.CurrentColorVarietyId);
 
+            // CR-11: FARBSCHLAG FROM GENOTYPE post-sweep (fill-NULL-only, safe): existing DB animals
+            // with null ColorVarietyId whose stored Genotype matches a catalog entry get filled.
+            // Mirrors the plan-loop derivation; never overwrites a manually-set or name-matched value.
+            {
+                var noColor = await _db.Gerbils
+                    .Where(g => g.ColorVarietyId == null && g.Genotype != null)
+                    .Select(g => new { g.Id, g.Genotype })
+                    .ToListAsync();
+                foreach (var g in noColor)
+                {
+                    if (string.IsNullOrWhiteSpace(g.Genotype) || g.Genotype!.Contains("??")) continue;
+                    Guid? derivedVid = null;
+                    foreach (var v in varietiesWithGeno)
+                        if (!string.IsNullOrWhiteSpace(v.CanonicalGenotype)
+                            && GenotypePotentiallyMatches(g.Genotype, v.CanonicalGenotype))
+                        { derivedVid = v.Id; break; }
+                    if (derivedVid is null) continue;
+                    fbDerivedFromGenotype++;
+                    if (execute)
+                    {
+                        var row = await _db.Gerbils.FindAsync(g.Id);
+                        if (row is not null && row.ColorVarietyId is null) row.ColorVarietyId = derivedVid;
+                    }
+                }
+                if (execute && fbDerivedFromGenotype > 0) await _db.SaveChangesAsync();
+            }
+
             // HERKUNFT BACKFILL (fill-NULL-only, safe): sweep all resident animals whose
             // OriginBreeder is null and fill it with a derived value or 'Zucht der Kleinen Chaoten'.
             // NEVER overwrites a non-null OriginBreeder (Julian: "alle Schreibweisen unterstützen").
@@ -524,6 +589,8 @@ namespace GerbilManagerWebAPI.Import
             int conflictsResolvedByDecision = loadable.Count(a => a.ResolvedByDecision);
             if (conflictsResolvedByDecision > 0)
                 notes.Add($"Konfliktauflösungen: {conflictsResolvedByDecision} Tier(e) anhand von conflict-decisions.json un-quarantänet (Genotyp/Farbschlag der Züchterin ist maßgeblich).");
+            if (fbDerivedFromGenotype > 0)
+                notes.Add($"Farbschlag aus Genotyp: {fbDerivedFromGenotype} Tier(e) ohne expliziten Farbschlag-Namen wurden über den Katalog-Genotyp-Abgleich zugeordnet (band-aware Deep-Band-Tiere).");
             if (!execute) notes.Add("DRY-RUN: nichts gespeichert. /import/execute lädt die konfliktfreien Daten.");
 
             return new ImportReport(
@@ -532,7 +599,7 @@ namespace GerbilManagerWebAPI.Import
                 Animals: new AnimalSummary(
                     animals.Count, animalsCreated, linked, fbMatched, fbUnmatched, animalsExisting,
                     new QuarantineSummary(conflicts, stubs, dateOnly, ambiguous, conflicts + stubs),
-                    parentLinksAdded, conflictsResolvedByDecision),
+                    parentLinksAdded, conflictsResolvedByDecision, fbDerivedFromGenotype),
                 Photos: new PhotoSummary(photosAttached, photosMissing),
                 Samples: samples,
                 Notes: notes,
@@ -570,6 +637,23 @@ namespace GerbilManagerWebAPI.Import
 
         private static string StripCaret(string allele) => allele.Replace("^", "");
 
+        /// <summary>CR-11: check if a composed animal genotype is compatible with a catalog canonical
+        /// genotype. Both are space-separated 8-locus tokens (e.g. "aa CC DD ee GG PP spsp rere").
+        /// "??" in either position is a wildcard. The first 8 tokens are compared; any trailing
+        /// Sls token is ignored (it is outside the base 8-locus contract).</summary>
+        private static bool GenotypePotentiallyMatches(string animalGeno, string catalogGeno)
+        {
+            var a = animalGeno.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+            var c = catalogGeno.Split(' ', StringSplitOptions.RemoveEmptyEntries);
+            if (a.Length < 8 || c.Length < 8) return false;
+            for (int i = 0; i < 8; i++)
+            {
+                if (a[i] == "??" || c[i] == "??") continue;
+                if (!string.Equals(a[i], c[i], StringComparison.OrdinalIgnoreCase)) return false;
+            }
+            return true;
+        }
+
         private static Gender InferGender(SourceAnimal a, HashSet<string> sires, HashSet<string> dams)
         {
             // Box colour (blue=male, white=female) is the authoritative breeder signal — prefer it

GerbilManagerWebAPI/Migrations/20260606154816_UniqueExternalRef.cs

@@ -0,0 +1,29 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace GerbilManagerWebAPI.Migrations
+{
+    /// <inheritdoc />
+    public partial class UniqueExternalRef : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_Gerbils_ExternalRef",
+                table: "Gerbils",
+                column: "ExternalRef",
+                unique: true,
+                filter: "\"ExternalRef\" IS NOT NULL");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Gerbils_ExternalRef",
+                table: "Gerbils");
+        }
+    }
+}

GerbilManagerWebAPI/Migrations/ApplicationContextModelSnapshot.cs

@@ -807,6 +807,10 @@ namespace GerbilManagerWebAPI.Migrations
 
                     b.HasIndex("EnclosureId");
 
+                    b.HasIndex("ExternalRef")
+                        .IsUnique()
+                        .HasFilter("\"ExternalRef\" IS NOT NULL");
+
                     b.HasIndex("LitterId");
 
                     b.HasIndex("OriginContactId");