rebuild(stage-3): establish accounts permissions and secure settings

next/backend/database/migrations/m0002_model_pool.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+import sqlite3
+
+from backend.database.migrations.runner import Migration
+
+
+def upgrade(connection: sqlite3.Connection) -> None:
+    connection.execute(
+        """
+        CREATE TABLE llm_models (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            display_name TEXT NOT NULL,
+            display_name_key TEXT NOT NULL UNIQUE,
+            base_url TEXT NOT NULL,
+            model_identifier TEXT NOT NULL,
+            encrypted_api_key TEXT NOT NULL,
+            created_at TEXT NOT NULL,
+            updated_at TEXT NOT NULL,
+            updated_by INTEGER NOT NULL REFERENCES users(id) ON DELETE RESTRICT
+        )
+        """
+    )
+    connection.execute(
+        """
+        CREATE TABLE llm_configuration (
+            id INTEGER PRIMARY KEY CHECK (id = 1),
+            primary_model_id INTEGER REFERENCES llm_models(id) ON DELETE RESTRICT,
+            fallback_model_id INTEGER REFERENCES llm_models(id) ON DELETE RESTRICT,
+            updated_at TEXT,
+            updated_by INTEGER REFERENCES users(id) ON DELETE RESTRICT,
+            CHECK (
+                fallback_model_id IS NULL
+                OR primary_model_id IS NULL
+                OR fallback_model_id <> primary_model_id
+            )
+        )
+        """
+    )
+    connection.execute("INSERT INTO llm_configuration (id) VALUES (1)")
+
+
+def downgrade(connection: sqlite3.Connection) -> None:
+    connection.execute("DROP TABLE llm_configuration")
+    connection.execute("DROP TABLE llm_models")
+
+
+MIGRATION = Migration(
+    version=2,
+    name="create_model_pool",
+    signature="model-pool:v1:models-primary-fallback-encrypted-key",
+    upgrade=upgrade,
+    downgrade=downgrade,
+)