- script_builder endpoint: pg_advisory_xact_lock on user_id before
session count check, preventing concurrent creates from both passing
the MAX_SESSIONS_PER_USER guard
- script_builder_service send_message: pg_advisory_xact_lock on session_id
before message count check, preventing concurrent sends from both
passing the MAX_MESSAGES_PER_SESSION guard
- script_builder_service save_to_library: replace check-then-insert slug
logic with IntegrityError retry loop (3 attempts with fresh UUID suffix);
add unique constraint on script_templates.slug (migration 070)
- ScriptBuilderPage: add creatingSessionRef to serialize concurrent
handleSend calls that would otherwise both call createSession() while
session is still null
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
cb33787c08