hotpatch(cloud): add llm load balancing

surfsense_backend/alembic/versions/84_migrate_global_llm_configs_to_auto_mode.py

@@ -0,0 +1,75 @@
+"""Migrate global LLM configs to Auto mode
+
+Revision ID: 84
+Revises: 83
+
+This migration updates existing search spaces that use global LLM configs
+(negative IDs) to use the new Auto mode (ID 0) instead.
+
+Auto mode uses LiteLLM Router to automatically load balance requests across
+all configured global LLM providers, which helps avoid rate limits.
+
+Changes:
+1. Update agent_llm_id from negative values to 0 (Auto mode)
+2. Update document_summary_llm_id from negative values to 0 (Auto mode)
+3. Update NULL values to 0 (Auto mode) as the new default
+
+Note: This migration preserves any custom user-created LLM configs (positive IDs).
+"""
+
+from collections.abc import Sequence
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision: str = "84"
+down_revision: str | None = "83"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    """Migrate global LLM config IDs (negative) and NULL to Auto mode (0)."""
+    # Update agent_llm_id: convert negative values and NULL to 0 (Auto mode)
+    op.execute(
+        """
+        UPDATE searchspaces 
+        SET agent_llm_id = 0 
+        WHERE agent_llm_id < 0 OR agent_llm_id IS NULL
+        """
+    )
+
+    # Update document_summary_llm_id: convert negative values and NULL to 0 (Auto mode)
+    op.execute(
+        """
+        UPDATE searchspaces 
+        SET document_summary_llm_id = 0 
+        WHERE document_summary_llm_id < 0 OR document_summary_llm_id IS NULL
+        """
+    )
+
+
+def downgrade() -> None:
+    """Revert Auto mode back to the first global config (ID -1).
+
+    Note: This is a best-effort revert. We cannot know which specific
+    global config each search space was using before, so we default
+    to -1 (typically the first/primary global config).
+    """
+    # Revert agent_llm_id from Auto mode (0) back to first global config (-1)
+    op.execute(
+        """
+        UPDATE searchspaces 
+        SET agent_llm_id = -1 
+        WHERE agent_llm_id = 0
+        """
+    )
+
+    # Revert document_summary_llm_id from Auto mode (0) back to first global config (-1)
+    op.execute(
+        """
+        UPDATE searchspaces 
+        SET document_summary_llm_id = -1 
+        WHERE document_summary_llm_id = 0
+        """
+    )