resolve_scene_refinement_keys now derives purely from split_scenes — drops
the scene_count parameter AND both divergence fallbacks (the band-aids).
Generation reads per-scene keys from the canonical raw split and GUARDS that
its text-split count (prompt_to_encode) matches; on mismatch it screams and
falls back to default-key attribution rather than land a key on the wrong
scene. bridge.scene_refinement_keys + the /preview callers drop scene_count.
Reset (_v2_reset_prompt_keys) now wipes refinement_key_pool_for(prompt), so
the pool is one canonical answer shared with the reset-confirmation modal.
That removes the last user of prompt_scene_shortcut_keys, so its entire
internal split is deleted (and its 3 tests, covered by split_scenes tests).
Tests: 20 refinement-key + 140 movie_editor pass. Generation path needs an
in-app smoke test (no model here) — the guard makes a desync loud, not silent.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
