The 85% compaction autoraise exists to stop wasting the small advertised
272K Codex window. -900k large-context picker variants (#92797) run at
~900K, where the global compression.threshold (default 50%, ~450K) is the
right behavior — autoraising them to 85% (~765K) would delay compaction
far past what the user configured.
- _is_codex_gpt54_or_gpt55() excludes valid -900k variants, so both the
85% override and the one-time autoraise notice skip those sessions.
- Base slugs are unchanged: 272K window + 85% autoraise.
- Tests: variant/base threshold pairs incl. namespaced ids; docs note in
the -900k section.
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