Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/migrations/187_add_usage_log_session_id.sql

@@ -0,0 +1,14 @@
+-- Persist the explicit client-provided request session/conversation identifier
+-- (e.g. the session_id / X-Session-Id / X-Conversation-ID request headers) so
+-- usage rows can be correlated by session for querying.
+--
+-- Nullable with no default: on PostgreSQL 11+ this is a metadata-only change, so
+-- it does NOT rewrite the (potentially large) usage_logs table. Absent/invalid
+-- session identifiers stay NULL. Only explicit client correlation identity is
+-- stored here; prompt_cache_key and content-derived sticky hashes are never
+-- persisted as session_id.
+ALTER TABLE usage_logs ADD COLUMN IF NOT EXISTS session_id VARCHAR(255);
+
+-- Batch image usage is recorded asynchronously after the originating HTTP
+-- request has finished, so retain the same sanitized identifier on the job.
+ALTER TABLE batch_image_jobs ADD COLUMN IF NOT EXISTS session_id VARCHAR(255);