Gateway hygiene pre-compression only checked model.context_length from
the top-level config, missing per-model context_length defined in
custom_providers entries. This caused premature compression for custom
provider users (e.g. 128K default instead of 200K configured).
The AIAgent's own compressor already reads custom_providers correctly
(run_agent.py lines 1171-1189). This adds the same fallback to the
gateway hygiene path, running after runtime provider resolution so
the base_url is available for matching.
4a7c17fca5