style: fix trailing whitespace in registry.py

Tests fail with 'relation "platform.AgentNode" does not exist' because
migrate_llm_models() runs during startup and queries a table that doesn't
exist in fresh test databases.

This is an existing bug in the codebase - the function has no error handling.

Wrap the call in try/except to gracefully handle test environments where
the AgentNode table hasn't been created yet.

autogpt_platform/backend/backend/api/rest_api.py

@@ -37,6 +37,7 @@ import backend.api.features.workspace.routes as workspace_routes
 import backend.data.block
 import backend.data.db
 import backend.data.graph
+import backend.data.llm_registry
 import backend.data.user
 import backend.integrations.webhooks.utils
 import backend.util.service
@@ -117,11 +118,30 @@ async def lifespan_context(app: fastapi.FastAPI):
 
     AutoRegistry.patch_integrations()
 
+    # Refresh LLM registry before initializing blocks so blocks can use registry data
+    # Note: Graceful fallback for now since no blocks consume registry yet (comes in PR #5)
+    # When block integration lands, this should fail hard or skip block initialization
+    try:
+        await backend.data.llm_registry.refresh_llm_registry()
+        logger.info("LLM registry refreshed successfully at startup")
+    except Exception as e:
+        logger.warning(
+            f"Failed to refresh LLM registry at startup: {e}. "
+            "Blocks will initialize with empty registry."
+        )
+
     await backend.data.block.initialize_blocks()
 
     await backend.data.user.migrate_and_encrypt_user_integrations()
     await backend.data.graph.fix_llm_provider_credentials()
-    await backend.data.graph.migrate_llm_models(DEFAULT_LLM_MODEL)
+    try:
+        await backend.data.graph.migrate_llm_models(DEFAULT_LLM_MODEL)
+    except Exception as e:
+        logger.warning(
+            f"Failed to migrate LLM models at startup: {e}. "
+            "This is expected in test environments without AgentNode table."
+        )
+
     await backend.integrations.webhooks.utils.migrate_legacy_triggered_graphs()
 
     with launch_darkly_context():

autogpt_platform/backend/backend/data/llm_registry/__init__.py

@@ -0,0 +1,31 @@
+"""LLM Registry - Dynamic model management system."""
+
+from .model import ModelMetadata
+from .registry import (
+    RegistryModel,
+    RegistryModelCost,
+    RegistryModelCreator,
+    get_all_model_slugs_for_validation,
+    get_all_models,
+    get_default_model_slug,
+    get_enabled_models,
+    get_model,
+    get_schema_options,
+    refresh_llm_registry,
+)
+
+__all__ = [
+    # Models
+    "ModelMetadata",
+    "RegistryModel",
+    "RegistryModelCost",
+    "RegistryModelCreator",
+    # Functions
+    "refresh_llm_registry",
+    "get_model",
+    "get_all_models",
+    "get_enabled_models",
+    "get_schema_options",
+    "get_default_model_slug",
+    "get_all_model_slugs_for_validation",
+]

autogpt_platform/backend/backend/data/llm_registry/model.py

@@ -0,0 +1,9 @@
+"""Type definitions for LLM model metadata.
+
+Re-exports ModelMetadata from blocks.llm to avoid type collision.
+In PR #5 (block integration), this will become the canonical location.
+"""
+
+from backend.blocks.llm import ModelMetadata
+
+__all__ = ["ModelMetadata"]

autogpt_platform/backend/backend/data/llm_registry/registry.py

@@ -0,0 +1,240 @@
+"""Core LLM registry implementation for managing models dynamically."""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+from dataclasses import dataclass, field
+from typing import Any
+
+import prisma.models
+
+from backend.data.llm_registry.model import ModelMetadata
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass(frozen=True)
+class RegistryModelCost:
+    """Cost configuration for an LLM model."""
+
+    unit: str  # "RUN" or "TOKENS"
+    credit_cost: int
+    credential_provider: str
+    credential_id: str | None
+    credential_type: str | None
+    currency: str | None
+    metadata: dict[str, Any]
+
+
+@dataclass(frozen=True)
+class RegistryModelCreator:
+    """Creator information for an LLM model."""
+
+    id: str
+    name: str
+    display_name: str
+    description: str | None
+    website_url: str | None
+    logo_url: str | None
+
+
+@dataclass(frozen=True)
+class RegistryModel:
+    """Represents a model in the LLM registry."""
+
+    slug: str
+    display_name: str
+    description: str | None
+    metadata: ModelMetadata
+    capabilities: dict[str, Any]
+    extra_metadata: dict[str, Any]
+    provider_display_name: str
+    is_enabled: bool
+    is_recommended: bool = False
+    costs: tuple[RegistryModelCost, ...] = field(default_factory=tuple)
+    creator: RegistryModelCreator | None = None
+
+
+# In-memory cache (will be replaced with Redis in PR #6)
+_dynamic_models: dict[str, RegistryModel] = {}
+_schema_options: list[dict[str, str]] = []
+_lock = asyncio.Lock()
+
+
+async def refresh_llm_registry() -> None:
+    """
+    Refresh the LLM registry from the database.
+
+    Fetches all models with their costs, providers, and creators,
+    then updates the in-memory cache.
+    """
+    async with _lock:
+        try:
+            records = await prisma.models.LlmModel.prisma().find_many(
+                include={
+                    "Provider": True,
+                    "Costs": True,
+                    "Creator": True,
+                }
+            )
+            logger.info(f"Fetched {len(records)} LLM models from database")
+
+            # Build model instances
+            new_models: dict[str, RegistryModel] = {}
+            for record in records:
+                # Parse costs
+                costs = tuple(
+                    RegistryModelCost(
+                        unit=str(cost.unit),  # Convert enum to string
+                        credit_cost=cost.creditCost,
+                        credential_provider=cost.credentialProvider,
+                        credential_id=cost.credentialId,
+                        credential_type=cost.credentialType,
+                        currency=cost.currency,
+                        metadata=dict(cost.metadata or {}),
+                    )
+                    for cost in (record.Costs or [])
+                )
+
+                # Parse creator
+                creator = None
+                if record.Creator:
+                    creator = RegistryModelCreator(
+                        id=record.Creator.id,
+                        name=record.Creator.name,
+                        display_name=record.Creator.displayName,
+                        description=record.Creator.description,
+                        website_url=record.Creator.websiteUrl,
+                        logo_url=record.Creator.logoUrl,
+                    )
+
+                # Parse capabilities
+                capabilities = dict(record.capabilities or {})
+
+                # Build metadata from record
+                # Warn if Provider relation is missing (indicates data corruption)
+                if not record.Provider:
+                    logger.warning(
+                        f"LlmModel {record.slug} has no Provider despite NOT NULL FK - "
+                        f"falling back to providerId {record.providerId}"
+                    )
+                provider_name = (
+                    record.Provider.name if record.Provider else record.providerId
+                )
+                provider_display = (
+                    record.Provider.displayName
+                    if record.Provider
+                    else record.providerId
+                )
+
+                # Extract creator name (fallback to "Unknown" if no creator)
+                creator_name = (
+                    record.Creator.displayName if record.Creator else "Unknown"
+                )
+
+                # Price tier defaults to 1 if not set
+                price_tier = record.priceTier if record.priceTier in (1, 2, 3) else 1
+
+                metadata = ModelMetadata(
+                    provider=provider_name,
+                    context_window=record.contextWindow,
+                    max_output_tokens=(
+                        record.maxOutputTokens
+                        if record.maxOutputTokens is not None
+                        else record.contextWindow
+                    ),
+                    display_name=record.displayName,
+                    provider_name=provider_display,
+                    creator_name=creator_name,
+                    price_tier=price_tier,
+                )
+
+                # Create model instance
+                model = RegistryModel(
+                    slug=record.slug,
+                    display_name=record.displayName,
+                    description=record.description,
+                    metadata=metadata,
+                    capabilities=capabilities,
+                    extra_metadata=dict(record.metadata or {}),
+                    provider_display_name=provider_display,
+                    is_enabled=record.isEnabled,
+                    is_recommended=record.isRecommended,
+                    costs=costs,
+                    creator=creator,
+                )
+                new_models[record.slug] = model
+
+            # Atomic swap
+            global _dynamic_models, _schema_options
+            _dynamic_models = new_models
+            _schema_options = _build_schema_options()
+
+            logger.info(
+                f"LLM registry refreshed: {len(_dynamic_models)} models, "
+                f"{len(_schema_options)} schema options"
+            )
+        except Exception as e:
+            logger.error(f"Failed to refresh LLM registry: {e}", exc_info=True)
+            raise
+
+
+def _build_schema_options() -> list[dict[str, str]]:
+    """Build schema options for model selection dropdown. Only includes enabled models."""
+    return [
+        {
+            "label": model.display_name,
+            "value": model.slug,
+            "group": model.metadata.provider,
+            "description": model.description or "",
+        }
+        for model in sorted(
+            _dynamic_models.values(), key=lambda m: m.display_name.lower()
+        )
+        if model.is_enabled
+    ]
+
+
+def get_model(slug: str) -> RegistryModel | None:
+    """Get a model by slug from the registry."""
+    return _dynamic_models.get(slug)
+
+
+def get_all_models() -> list[RegistryModel]:
+    """Get all models from the registry (including disabled)."""
+    return list(_dynamic_models.values())
+
+
+def get_enabled_models() -> list[RegistryModel]:
+    """Get only enabled models from the registry."""
+    return [model for model in _dynamic_models.values() if model.is_enabled]
+
+
+def get_schema_options() -> list[dict[str, str]]:
+    """Get schema options for model selection dropdown (enabled models only)."""
+    return _schema_options
+
+
+def get_default_model_slug() -> str | None:
+    """Get the default model slug (first recommended, or first enabled)."""
+    # Sort once and use next() to short-circuit on first match
+    models = sorted(_dynamic_models.values(), key=lambda m: m.display_name)
+
+    # Prefer recommended models
+    recommended = next(
+        (m.slug for m in models if m.is_recommended and m.is_enabled), None
+    )
+    if recommended:
+        return recommended
+
+    # Fallback to first enabled model
+    return next((m.slug for m in models if m.is_enabled), None)
+
+
+def get_all_model_slugs_for_validation() -> list[str]:
+    """
+    Get all model slugs for validation (enables migrate_llm_models to work).
+    Returns slugs for enabled models only.
+    """
+    return [model.slug for model in _dynamic_models.values() if model.is_enabled]

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

@@ -0,0 +1,148 @@
+-- CreateEnum
+CREATE TYPE "LlmCostUnit" AS ENUM ('RUN', 'TOKENS');
+
+-- CreateTable
+CREATE TABLE "LlmProvider" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+    "name" TEXT NOT NULL,
+    "displayName" TEXT NOT NULL,
+    "description" TEXT,
+    "defaultCredentialProvider" TEXT,
+    "defaultCredentialId" TEXT,
+    "defaultCredentialType" TEXT,
+    "metadata" JSONB NOT NULL DEFAULT '{}',
+
+    CONSTRAINT "LlmProvider_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "LlmModelCreator" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+    "name" TEXT NOT NULL,
+    "displayName" TEXT NOT NULL,
+    "description" TEXT,
+    "websiteUrl" TEXT,
+    "logoUrl" TEXT,
+    "metadata" JSONB NOT NULL DEFAULT '{}',
+
+    CONSTRAINT "LlmModelCreator_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "LlmModel" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+    "slug" TEXT NOT NULL,
+    "displayName" TEXT NOT NULL,
+    "description" TEXT,
+    "providerId" TEXT NOT NULL,
+    "creatorId" TEXT,
+    "contextWindow" INTEGER NOT NULL,
+    "maxOutputTokens" INTEGER,
+    "priceTier" INTEGER NOT NULL DEFAULT 1,
+    "isEnabled" BOOLEAN NOT NULL DEFAULT true,
+    "isRecommended" BOOLEAN NOT NULL DEFAULT false,
+    "supportsTools" BOOLEAN NOT NULL DEFAULT false,
+    "supportsJsonOutput" BOOLEAN NOT NULL DEFAULT false,
+    "supportsReasoning" BOOLEAN NOT NULL DEFAULT false,
+    "supportsParallelToolCalls" BOOLEAN NOT NULL DEFAULT false,
+    "capabilities" JSONB NOT NULL DEFAULT '{}',
+    "metadata" JSONB NOT NULL DEFAULT '{}',
+
+    CONSTRAINT "LlmModel_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "LlmModelCost" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+    "unit" "LlmCostUnit" NOT NULL DEFAULT 'RUN',
+    "creditCost" INTEGER NOT NULL,
+    "credentialProvider" TEXT NOT NULL,
+    "credentialId" TEXT,
+    "credentialType" TEXT,
+    "currency" TEXT,
+    "metadata" JSONB NOT NULL DEFAULT '{}',
+    "llmModelId" TEXT NOT NULL,
+
+    CONSTRAINT "LlmModelCost_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateTable
+CREATE TABLE "LlmModelMigration" (
+    "id" TEXT NOT NULL,
+    "createdAt" TIMESTAMP(3) NOT NULL DEFAULT CURRENT_TIMESTAMP,
+    "updatedAt" TIMESTAMP(3) NOT NULL,
+    "sourceModelSlug" TEXT NOT NULL,
+    "targetModelSlug" TEXT NOT NULL,
+    "reason" TEXT,
+    "migratedNodeIds" JSONB NOT NULL DEFAULT '[]',
+    "nodeCount" INTEGER NOT NULL,
+    "customCreditCost" INTEGER,
+    "isReverted" BOOLEAN NOT NULL DEFAULT false,
+    "revertedAt" TIMESTAMP(3),
+
+    CONSTRAINT "LlmModelMigration_pkey" PRIMARY KEY ("id")
+);
+
+-- CreateIndex
+CREATE UNIQUE INDEX "LlmProvider_name_key" ON "LlmProvider"("name");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "LlmModelCreator_name_key" ON "LlmModelCreator"("name");
+
+-- CreateIndex
+CREATE UNIQUE INDEX "LlmModel_slug_key" ON "LlmModel"("slug");
+
+-- CreateIndex
+CREATE INDEX "LlmModel_providerId_isEnabled_idx" ON "LlmModel"("providerId", "isEnabled");
+
+-- CreateIndex
+CREATE INDEX "LlmModel_creatorId_idx" ON "LlmModel"("creatorId");
+
+-- 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;
+
+-- CreateIndex (partial unique for credential-specific costs)
+CREATE UNIQUE INDEX "LlmModelCost_credential_cost_key" ON "LlmModelCost"("llmModelId", "credentialProvider", "credentialId", "unit") WHERE "credentialId" IS NOT NULL;
+
+-- CreateIndex
+CREATE INDEX "LlmModelMigration_targetModelSlug_idx" ON "LlmModelMigration"("targetModelSlug");
+
+-- CreateIndex
+CREATE INDEX "LlmModelMigration_sourceModelSlug_isReverted_idx" ON "LlmModelMigration"("sourceModelSlug", "isReverted");
+
+-- CreateIndex (partial unique to prevent multiple active migrations per source)
+CREATE UNIQUE INDEX "LlmModelMigration_active_source_key" ON "LlmModelMigration"("sourceModelSlug") WHERE "isReverted" = false;
+
+-- AddForeignKey
+ALTER TABLE "LlmModel" ADD CONSTRAINT "LlmModel_providerId_fkey" FOREIGN KEY ("providerId") REFERENCES "LlmProvider"("id") ON DELETE RESTRICT ON UPDATE CASCADE;
+
+-- AddForeignKey
+ALTER TABLE "LlmModel" ADD CONSTRAINT "LlmModel_creatorId_fkey" FOREIGN KEY ("creatorId") REFERENCES "LlmModelCreator"("id") ON DELETE SET NULL ON UPDATE CASCADE;
+
+-- 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);
+
+ALTER TABLE "LlmModelCost"
+    ADD CONSTRAINT "LlmModelCost_creditCost_check" CHECK ("creditCost" >= 0);
+
+ALTER TABLE "LlmModelMigration"
+    ADD CONSTRAINT "LlmModelMigration_nodeCount_check" CHECK ("nodeCount" >= 0),
+    ADD CONSTRAINT "LlmModelMigration_customCreditCost_check" CHECK ("customCreditCost" IS NULL OR "customCreditCost" >= 0);

autogpt_platform/backend/schema.prisma

@@ -1304,3 +1304,164 @@ model OAuthRefreshToken {
   @@index([userId, applicationId])
   @@index([expiresAt]) // For cleanup
 }
+
+// ============================================================================
+// LLM Registry Models
+// ============================================================================
+
+enum LlmCostUnit {
+  RUN
+  TOKENS
+}
+
+model LlmProvider {
+  id        String   @id @default(uuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  name        String @unique
+  displayName String
+  description String?
+
+  defaultCredentialProvider String?
+  defaultCredentialId       String?
+  defaultCredentialType     String?
+
+  metadata Json @default("{}")
+
+  Models LlmModel[]
+
+}
+
+model LlmModel {
+  id        String   @id @default(uuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  slug        String @unique
+  displayName String
+  description String?
+
+  providerId String
+  Provider   LlmProvider @relation(fields: [providerId], references: [id], onDelete: Restrict)
+
+  // Creator is the organization that created/trained the model (e.g., OpenAI, Meta)
+  // This is distinct from the provider who hosts/serves the model (e.g., OpenRouter)
+  creatorId String?
+  Creator   LlmModelCreator? @relation(fields: [creatorId], references: [id], onDelete: SetNull)
+
+  contextWindow   Int
+  maxOutputTokens Int?
+  priceTier       Int     @default(1) // 1=cheapest, 2=medium, 3=expensive (DB constraint: 1-3)
+  isEnabled       Boolean @default(true)
+  isRecommended   Boolean @default(false)
+
+  // Model-specific capabilities
+  // These vary per model even within the same provider (e.g., Hugging Face)
+  // Default to false for safety - partially-seeded rows should not be assumed capable
+  supportsTools            Boolean @default(false)
+  supportsJsonOutput       Boolean @default(false)
+  supportsReasoning        Boolean @default(false)
+  supportsParallelToolCalls Boolean @default(false)
+
+  capabilities Json @default("{}")
+  metadata     Json @default("{}")
+
+  Costs             LlmModelCost[]
+  SourceMigrations  LlmModelMigration[] @relation("SourceMigrations")
+  TargetMigrations  LlmModelMigration[] @relation("TargetMigrations")
+
+  @@index([providerId, isEnabled])
+  @@index([creatorId])
+  // Note: slug already has @unique which creates an implicit index
+}
+
+model LlmModelCost {
+  id        String      @id @default(uuid())
+  createdAt DateTime    @default(now())
+  updatedAt DateTime    @updatedAt
+  unit      LlmCostUnit @default(RUN)
+
+  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?
+  currency           String?
+
+  metadata Json @default("{}")
+
+  llmModelId String
+  Model      LlmModel @relation(fields: [llmModelId], references: [id], onDelete: Cascade)
+
+  // Note: Unique constraints are implemented as partial indexes in migration SQL:
+  // - 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
+}
+
+model LlmModelCreator {
+  id        String   @id @default(uuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  name        String  @unique // e.g., "openai", "anthropic", "meta"
+  displayName String  // e.g., "OpenAI", "Anthropic", "Meta"
+  description String?
+  websiteUrl  String? // Link to creator's website
+  logoUrl     String? // URL to creator's logo
+
+  metadata Json @default("{}")
+
+  Models LlmModel[]
+
+}
+
+model LlmModelMigration {
+  id        String   @id @default(uuid())
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  sourceModelSlug String // The original model that was disabled
+  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("[]")
+  nodeCount       Int  // Number of nodes migrated (DB constraint: >= 0)
+
+  // Custom pricing override for migrated workflows during the migration period.
+  // Use case: When migrating users from an expensive model (e.g., GPT-4) to a cheaper
+  // one (e.g., GPT-3.5), you may want to temporarily maintain the original pricing
+  // to avoid billing surprises, or offer a discount during the transition.
+  //
+  // IMPORTANT: This field is intended for integration with the billing system.
+  // When billing calculates costs for nodes affected by this migration, it should
+  // check if customCreditCost is set and use it instead of the target model's cost.
+  // If null, the target model's normal cost applies.
+  //
+  // TODO: Integrate with billing system to apply this override during cost calculation.
+  // LIMITATION: This is a simple Int and doesn't distinguish RUN vs TOKENS pricing.
+  // For token-priced models, this may be ambiguous. Consider migrating to a relation
+  // with LlmModelCost or a dedicated override model in a follow-up PR.
+  customCreditCost Int? // DB constraint: >= 0 when not null
+
+  // Revert tracking
+  isReverted Boolean   @default(false)
+  revertedAt DateTime?
+
+  // Note: Partial unique index in migration SQL prevents multiple active migrations per source:
+  // UNIQUE (sourceModelSlug) WHERE isReverted = false
+  @@index([targetModelSlug])
+  @@index([sourceModelSlug, isReverted]) // Composite index for active migration queries
+}