Previously the normalize_callback_names call only ran when the existing
litellm_settings DB row already had a success_callback key. On the very
first write (no row yet, or row missing the key), incoming mixed-case
values like ["SQS", "sQs"] persisted as-is. delete_callback (lowercase
lookup) then could not find them, and a follow-up /config/update would
union normalized incoming with mixed-case stored entries, producing
duplicates.
Always normalize incoming success_callback before merging, and dedupe
both the standalone first-write case and the union-with-existing case.
Adds test_success_callback_normalized_on_first_write covering the
no-existing-row path; the existing union test still passes.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
