fix(schema): address Majdyz review feedback

- Add FK constraints on LlmModelMigration (sourceModelSlug, targetModelSlug → LlmModel.slug)
- Remove unused @@index([credentialProvider]) on LlmModelCost
- Remove redundant @@index([isReverted]) on LlmModelMigration (covered by composite)
- Add documentation for credentialProvider field explaining its purpose
- Add reverse relation fields to LlmModel (SourceMigrations, TargetMigrations)

Fixes data integrity: typos in migration slugs now caught at DB level.

autogpt_platform/backend/migrations/20260310_add_llm_registry_schema/migration.sql

@@ -106,9 +106,6 @@ CREATE INDEX "LlmModel_providerId_isEnabled_idx" ON "LlmModel"("providerId", "is
 -- CreateIndex
 CREATE INDEX "LlmModel_creatorId_idx" ON "LlmModel"("creatorId");
 
--- CreateIndex
-CREATE INDEX "LlmModelCost_credentialProvider_idx" ON "LlmModelCost"("credentialProvider");
-
 -- CreateIndex (partial unique for default costs - no specific credential)
 CREATE UNIQUE INDEX "LlmModelCost_default_cost_key" ON "LlmModelCost"("llmModelId", "credentialProvider", "unit") WHERE "credentialId" IS NULL;
 
@@ -118,9 +115,6 @@ CREATE UNIQUE INDEX "LlmModelCost_credential_cost_key" ON "LlmModelCost"("llmMod
 -- CreateIndex
 CREATE INDEX "LlmModelMigration_targetModelSlug_idx" ON "LlmModelMigration"("targetModelSlug");
 
--- CreateIndex
-CREATE INDEX "LlmModelMigration_isReverted_idx" ON "LlmModelMigration"("isReverted");
-
 -- CreateIndex
 CREATE INDEX "LlmModelMigration_sourceModelSlug_isReverted_idx" ON "LlmModelMigration"("sourceModelSlug", "isReverted");
 
@@ -136,6 +130,12 @@ ALTER TABLE "LlmModel" ADD CONSTRAINT "LlmModel_creatorId_fkey" FOREIGN KEY ("cr
 -- AddForeignKey
 ALTER TABLE "LlmModelCost" ADD CONSTRAINT "LlmModelCost_llmModelId_fkey" FOREIGN KEY ("llmModelId") REFERENCES "LlmModel"("id") ON DELETE CASCADE ON UPDATE CASCADE;
 
+-- AddForeignKey
+ALTER TABLE "LlmModelMigration" ADD CONSTRAINT "LlmModelMigration_sourceModelSlug_fkey" FOREIGN KEY ("sourceModelSlug") REFERENCES "LlmModel"("slug") ON DELETE RESTRICT ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "LlmModelMigration" ADD CONSTRAINT "LlmModelMigration_targetModelSlug_fkey" FOREIGN KEY ("targetModelSlug") REFERENCES "LlmModel"("slug") ON DELETE RESTRICT ON UPDATE CASCADE;
+
 -- AddCheckConstraints (enforce data integrity)
 ALTER TABLE "LlmModel"
     ADD CONSTRAINT "LlmModel_priceTier_check" CHECK ("priceTier" BETWEEN 1 AND 3);

autogpt_platform/backend/schema.prisma

@@ -1397,7 +1397,9 @@ model LlmModel {
   capabilities Json @default("{}")
   metadata     Json @default("{}")
 
-  Costs LlmModelCost[]
+  Costs             LlmModelCost[]
+  SourceMigrations  LlmModelMigration[] @relation("SourceMigrations")
+  TargetMigrations  LlmModelMigration[] @relation("TargetMigrations")
 
   @@index([providerId, isEnabled])
   @@index([creatorId])
@@ -1412,6 +1414,11 @@ model LlmModelCost {
 
   creditCost Int // DB constraint: >= 0
 
+  // Provider identifier (e.g., "openai", "anthropic", "openrouter")
+  // Used to determine which credential system provides the API key.
+  // Allows different pricing for:
+  // - Default provider costs (WHERE credentialId IS NULL)
+  // - User's own API key costs (WHERE credentialId IS NOT NULL)
   credentialProvider String
   credentialId       String?
   credentialType     String?
@@ -1426,7 +1433,6 @@ model LlmModelCost {
   // - One for default costs (WHERE credentialId IS NULL)
   // - One for credential-specific costs (WHERE credentialId IS NOT NULL)
   // This allows both provider-level defaults and credential-specific overrides
-  @@index([credentialProvider])
 }
 
 model LlmModelCreator {
@@ -1455,6 +1461,10 @@ model LlmModelMigration {
   targetModelSlug String // The model workflows were migrated to
   reason          String? // Why the migration happened (e.g., "Provider outage")
 
+  // FK constraints ensure slugs reference valid models
+  SourceModel LlmModel @relation("SourceMigrations", fields: [sourceModelSlug], references: [slug], onDelete: Restrict)
+  TargetModel LlmModel @relation("TargetMigrations", fields: [targetModelSlug], references: [slug], onDelete: Restrict)
+
   // Track affected nodes as JSON array of node IDs
   // Format: ["node-uuid-1", "node-uuid-2", ...]
   migratedNodeIds Json @default("[]")
@@ -1483,6 +1493,5 @@ model LlmModelMigration {
   // Note: Partial unique index in migration SQL prevents multiple active migrations per source:
   // UNIQUE (sourceModelSlug) WHERE isReverted = false
   @@index([targetModelSlug])
-  @@index([isReverted])
   @@index([sourceModelSlug, isReverted]) // Composite index for active migration queries
 }