Review-pass findings on the lazy-init deferral:
- No-op guard: the codex app-server usage callback assigns
compressor.context_length on EVERY response (same window each time).
The setter unconditionally invalidated the derived budgets, wiping
runtime corrections applied directly to threshold_tokens /
tail_token_budget (aux-context threshold sync) — those persisted on
main's eager init. Same-value assignment is now a no-op.
- Re-floor on genuinely new window: the setter invalidates budgets but
previously kept the stale threshold_percent, so a codex window switch
recomputed threshold_tokens from the new window with the old model's
floored percent. Re-apply the raise-only small-context floor from
_base_threshold_percent so percent and tokens derive from the same
window (guarded with getattr for object.__new__ test instances).
- Init log extracted to _emit_init_summary_once() and also fired from
the setter path, so a consumer assigning context_length before any
read no longer strands the startup line forever.
- threshold_tokens getter resolves the window into a local before
reading threshold_percent — correctness no longer depends on
left-to-right argument evaluation order.
- reasoning_timeouts: fix inaccurate 'tuples are immutable' comment
(the container is a list; safety comes from build-once-at-import),
document why the slug stays in the tuple.
Adds TestContextLengthSetterCoherence (3 tests): same-value assignment
preserves overrides; new-window assignment re-floors both directions.