Three related architecture changes, driven by a cost/simplicity trade-off:
1. **Shared encoder**: one DINOv3 LVD-1689M (WEB) processes both drone
and satellite images. Previously asymmetric — separate WEB (drone) and
SAT-493M (satellite) encoders. Saves ~303M frozen params and halves
VRAM for the image tower. Expected to lose some satellite-domain
inductive bias; MONA adapters pick up the slack.
2. **MONA in last 12/24 blocks**: adapters injected only in the top half
of the ViT. The lowest 12 blocks keep their pretrained features
untouched. Trainable MONA count drops from 14.0M (48 adapters × 2
encoders) to 3.5M (24 adapters × 1 encoder).
3. **No DINO_SAT**: `nn_models/DINO_SAT` is no longer loaded by the
default config. It stays on disk and the path param is kept for
backward compat with asymmetric checkpoints.
Parameter counts (with text fusion + LoRA + gates):
Before: 17.6M trainable / 733M total (2.35%)
After: 7.06M trainable / 434M total (1.63%)
Also fixes a pre-existing resume bug: checkpoints now record
`shared_encoder`, `baseline_mode`, `mona_bottleneck`, `mona_last_n_blocks`
so `AsymmetricEncoder.load_checkpoint` can rebuild the right architecture.
Old checkpoints still load (missing keys fall back to asymmetric defaults
via `ckpt.get(..., <default>)`).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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