Remember the session highlighter choice and toggle it when no explicit colour is given. Keep explicit palette/automation setters and No Color semantics, and preserve undoable formatting.
Two command/key regressions and four headless UI screenshots passed. Full cargo xtask ci passed all 8 steps with 3962 passed, 0 failed, 4 existing ignored using RUST_TEST_THREADS=1. Initial parallel run hit an unchanged Russian suggestion timing assertion; isolated unchanged binary passed at13ms. Native Word comparison pending.