Closes the ADR-185 §13.a follow-up (the tractable, data-independent one of
the three §6.7 gaps): the bound EmbeddingExtractor was random-Xavier-init
only, with NO way to load real weights — so it was structurally untrained.
This adds the *capability* to load weights whenever a trained checkpoint
exists. It does NOT itself produce trained/SOTA embeddings and does NOT
close §6.7 (still no trained checkpoint, no labeled data, no eval harness).
Serialization: not greenfield — EmbeddingExtractor already had
flatten_weights()/unflatten_weights() (flat Vec<f32>). wifi-densepose-aether
is a deliberately dependency-free std-only leaf crate (ADR-185 §13), so
rather than add safetensors/serde/bincode (which would undo the zero-dep
property), the on-disk format is raw little-endian f32 with a 12-byte header
(magic "AETHERW1" + u32 param count) — zero new deps.
Native (v2/crates/wifi-densepose-aether/src/embedding.rs):
- EmbeddingExtractor::save_weights(path) / load_weights(path). load_weights
never panics: errors on unreadable file, short/oversized payload, bad
magic, or a param-count mismatch (delegated to unflatten_weights).
- Default (no weights) construction is UNCHANGED — still random init,
clearly labeled untrained. Purely additive.
Python binding (python/src/bindings/aether.rs, .pyi):
- EmbeddingExtractor.load_weights(path) / save_weights(path) / param_count,
GIL-released, ValueError on bad input.
Tests (both Rust and Python, per the task):
- Rust unit (embedding.rs): load_weights_actually_replaces_weights_and_
round_trips proves the loaded weights MOVE the embedding away from the
random-init baseline (not a silent no-op), match the source extractor
(round-trip), and are bit-identical after the file round-trip; plus a
bad-magic/wrong-count rejection test.
- Cross-language golden (aether_weights_parity.rs + test_aether.py): a
shared deterministic weight formula (w[i]=k/65536-0.5, exact in f32+f64)
written to the AETHER format; both native Rust and the Python binding load
it and must produce the byte-identical embedding SHA-256
(tests/golden/aether_loaded_embedding.sha256) — proving the binding's
load path is bit-identical to native, and (vs the random baseline) that
the loaded weights are actually used.
Verified:
cargo test -p wifi-densepose-aether 98 passed, 0 failed
cargo test --features aether --test aether_parity
--test aether_weights_parity 3 passed, 0 failed
maturin develop --features aether + pytest test_aether.py 13/13 pass
default cargo build (no aether feature) clean
ADR-185 §13 flagged the `[aether]` wheel as linking the whole
`wifi-densepose-sensing-server` Axum/tokio/worldgraph/ruvector tree via the
non-optional deps of that crate. Hoist the pure-compute AETHER stack out so the
binding depends only on pure Rust.
New crate `wifi-densepose-aether` (std-only, ZERO external deps) holds the four
self-contained modules the AETHER surface needs — `embedding`, `graph_transformer`,
`sona`, `sparse_inference` (verified: no serde/tokio/axum/crate:: refs outside the
set; the four form a closed dependency graph). `wifi-densepose-sensing-server`
now `pub use`s them from the leaf crate, so its own code (`crate::embedding`, …)
and public API (`wifi_densepose_sensing_server::embedding`, …) are unchanged —
`main.rs`/`trainer.rs` untouched. The Python binding + parity test + `[aether]`
feature repoint at the leaf crate; the sensing-server dep is dropped from python.
MEASURED wheel size (maturin build --release --features aether --strip; each
wheel install-verified to actually contain `AetherConfig`):
BEFORE (aether -> sensing-server): 369,782 B (~361 KB)
AFTER (aether -> leaf crate): 319,719 B (~312 KB)
HONEST CORRECTION to the §9/§13 premise: the pre-hoist wheel was NOT over the
ADR-117 §5.4 5 MB budget — it was ~361 KB, ~14x under. Linker dead-code
elimination (--gc-sections on the pyo3 cdylib) already strips the unreached
server tree because the binding only reaches pure-compute symbols. So this is
"blows the budget" CLAIMED, not MEASURED. The hoist is still worthwhile and
lands the real, measured wins:
- `[aether]` build time 71s -> 12s (no server tree to compile),
- python/Cargo.lock -1238 lines (server tree no longer resolved),
- ~50 KB smaller wheel,
- honest, minimal declared dependency surface + removes the latent risk that a
future change makes some server code reachable and *then* bloats the wheel.
Verified this session (real counts):
- cargo test --features aether --test aether_parity: 2 passed / 0 failed
- pytest tests/test_aether.py (maturin develop --features aether): 9 passed
- cargo test -p wifi-densepose-sensing-server --no-default-features: 217 bin +
388 lib, 0 failed (no regression)
- cargo test -p wifi-densepose-aether: 96 passed (the relocated unit tests)
The §9/§13 wheel-size narrative in ADR-185 (owned by the ADR author) should be
corrected to reflect the measured reality — flagged to the team lead.
ruv