Multilingual embeddings: Madrid 0 → 19, Milan 0 → 5, and a trade-off we kept

The blocker for every non-anglophone city was the embedding model, not the pipeline. Adding potion-multilingual-128M unblocks them — and measuring it showed the fix is not free.

Why it is not a straight swap

On the seven hand-verified NYC pairs, against the full 2,400-dataset catalog:

Swapping wholesale would have bought non-English coverage with English accuracy — a 3.5× worse median rank on the catalog we know best. Interestingly it is not uniform: the multilingual model improves the two hardest cases (homicide 786→401, slums 1033→716) while degrading the easy ones.

So the model is chosen per catalog language. English cities keep the English model; everything else gets the multilingual one. The vector cache is keyed by model, because vectors from two models are not interchangeable and reusing them across would be a silent, invisible corruption.

The matches, read honestly

Milan is good — 4 of 5 plausible:

• Annual inflation (consumer prices) → Tasso di inflazione mensile (0.60)
• Installed renewable electricity capacity → Produzione netta di energia elettrica (0.67)
• Energy intensity of primary energy → Energia elettrica erogata da A2A (0.60)

Madrid is noisy — six near-identical "water area of lakes and rivers" indicators all matched Fuentes de agua para mascotas, drinking fountains for pets. The word agua dominated. But buried in the noise: installed renewable capacity → Inventario de instalaciones fotovoltaicas, which is exactly right.

The threshold problem is language-independent: 0.50 was calibrated on NYC and means something different in every other catalog. That remains the open issue, and it is now the main thing standing between this and a usable recommender.

Buenos Aires is unreachable, not empty

The portal closes the connection on anonymous package_search — RemoteDisconnected, on two attempts a day apart. Recorded in the registry as status: unreachable rather than as zero candidates, because those are different findings and collapsing them would overstate what we tested.