fix(results-schema): include Language in unique constraint for CvMatchResults

The unique constraint on cvMatcher.Results was defined as (CvDocumentId, JobDocumentId)
but the code checks for (CvDocumentId, JobDocumentId, Language). This mismatch caused
duplicate key violations when matching the same CV+Job in different languages.

Update the constraint to (CvDocumentId, JobDocumentId, Language) to allow different
languages for the same CV+Job pair while preventing true duplicates.

Resolves: Duplicate key constraint violations on concurrent/repeated match requests

Apis/cv-matcher-data/Migrations/20260529111000_UpdateResultsUniqueConstraintToIncludeLanguage.Designer.cs

@@ -0,0 +1,130 @@
+// <auto-generated />
+using System;
+using CvMatcher.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace CvMatcher.Data.Migrations
+{
+    [DbContext(typeof(CvMatcherDbContext))]
+    [Migration("20260529111000_UpdateResultsUniqueConstraintToIncludeLanguage")]
+    partial class UpdateResultsUniqueConstraintToIncludeLanguage
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasDefaultSchema("cvMatcher")
+                .HasAnnotation("ProductVersion", "10.0.7")
+                .HasAnnotation("Relational:MaxIdentifierLength", 128);
+
+            SqlServerModelBuilderExtensions.UseIdentityColumns(modelBuilder);
+
+            modelBuilder.Entity("CvMatcher.Data.Entities.AiPromptEntity", b =>
+                {
+                    b.Property<string>("Key")
+                        .HasMaxLength(128)
+                        .HasColumnType("nvarchar(128)");
+
+                    b.Property<string>("Language")
+                        .HasMaxLength(8)
+                        .HasColumnType("nvarchar(8)");
+
+                    b.Property<string>("Description")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(500)
+                        .HasColumnType("nvarchar(500)")
+                        .HasDefaultValue("");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("datetime2")
+                        .HasDefaultValueSql("SYSUTCDATETIME()");
+
+                    b.Property<string>("Value")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.HasKey("Key", "Language");
+
+                    b.ToTable("AiPrompts", "cvMatcher");
+                });
+
+            modelBuilder.Entity("CvMatcher.Data.Entities.CvMatchResultEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("datetime2")
+                        .HasDefaultValueSql("SYSUTCDATETIME()");
+
+                    b.Property<string>("CvDocumentId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<string>("JobDocumentId")
+                        .IsRequired()
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<string>("Language")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<string>("ResultJson")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<int>("Score")
+                        .HasColumnType("int");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("CvDocumentId", "JobDocumentId", "Language")
+                        .IsUnique();
+
+                    b.ToTable("Results", "cvMatcher");
+                });
+
+            modelBuilder.Entity("CvMatcher.Data.Entities.CvMatcherChatCacheEntity", b =>
+                {
+                    b.Property<string>("CacheKey")
+                        .HasMaxLength(64)
+                        .HasColumnType("nvarchar(64)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("datetime2")
+                        .HasDefaultValueSql("SYSUTCDATETIME()");
+
+                    b.Property<string>("Model")
+                        .IsRequired()
+                        .HasMaxLength(120)
+                        .HasColumnType("nvarchar(120)");
+
+                    b.Property<string>("ResponseText")
+                        .IsRequired()
+                        .HasColumnType("nvarchar(max)");
+
+                    b.Property<decimal>("Temperature")
+                        .HasColumnType("decimal(4,2)");
+
+                    b.HasKey("CacheKey");
+
+                    b.ToTable("ChatCache", "cvMatcher");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

Apis/cv-matcher-data/Migrations/20260529111000_UpdateResultsUniqueConstraintToIncludeLanguage.cs

@@ -0,0 +1,46 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace CvMatcher.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class UpdateResultsUniqueConstraintToIncludeLanguage : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // The Language column was added in migration 20260524140335, but the unique constraint
+            // was never updated from (CvDocumentId, JobDocumentId) to include Language.
+            // This caused duplicate key violations when matching the same CV+Job in different languages.
+
+            migrationBuilder.DropIndex(
+                name: "IX_Results_CvDocumentId_JobDocumentId",
+                schema: MigrationConstants.SchemaName,
+                table: "Results");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Results_CvDocumentId_JobDocumentId_Language",
+                schema: MigrationConstants.SchemaName,
+                table: "Results",
+                columns: new[] { "CvDocumentId", "JobDocumentId", "Language" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_Results_CvDocumentId_JobDocumentId_Language",
+                schema: MigrationConstants.SchemaName,
+                table: "Results");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Results_CvDocumentId_JobDocumentId",
+                schema: MigrationConstants.SchemaName,
+                table: "Results",
+                columns: new[] { "CvDocumentId", "JobDocumentId" },
+                unique: true);
+        }
+    }
+}

Apis/cv-matcher-data/Migrations/CvMatcherDbContextModelSnapshot.cs

@@ -88,7 +88,7 @@ namespace CvMatcher.Data.Migrations
 
                     b.HasKey("Id");
 
-                    b.HasIndex("CvDocumentId", "JobDocumentId")
+                    b.HasIndex("CvDocumentId", "JobDocumentId", "Language")
                         .IsUnique();
 
                     b.ToTable("Results", "cvMatcher");