emem-locate-and-recall

This skill turns a place name into signed Earth-observation facts in two REST calls.

When to invoke

The user asks about a measurable geospatial fact at a named place:

• "What's the current 2 m air temperature in Bengaluru?"
• "Show me the NDVI in the Sundarbans."
• "How does the soil pH look in central Iowa?"
• "What's the elevation of Mount Kilimanjaro?"

If the user has a cell64 already (a string like defi.zb493.xoso.zcb6a), skip the locate step and go straight to /v1/recall. If they want a thumbnail (visual preview) instead of numeric facts, use GET /v1/cells/{cell64}/scene.png directly.

How to invoke

The endpoint is https://emem.dev. Reads are public.

Step 1 — resolve the place name

curl -sf -X POST https://emem.dev/v1/locate \
  -H 'content-type: application/json' \
  -d '{"q":"Bengaluru, India"}' | jq '.cell64, .place_label, .via'

via reports how the name was resolved (embedded, cache, photon, nominatim, fallback). Treat via=fallback as low-confidence and ask the user to clarify.

Step 2 — recall the band(s)

curl -sf -X POST https://emem.dev/v1/recall \
  -H 'content-type: application/json' \
  -d '{"cell":"<CELL64_FROM_STEP_1>",
       "bands":["weather.temperature_2m","indices.ndvi"]}' \
  | jq '.facts[] | {band, value, unit, signed_at}, .receipt.fact_cids[]'

The response carries .facts[] (with value, unit, signed_at, signer_pubkey_b32) and .receipt (Ed25519 signature, fact_cids, schema_cid, registry_cid). The fact_cids[i] is a durable handle — re-fetching that CID from any responder in any year returns the same bytes.

Picking bands

The full band list is at https://emem.dev/v1/bands (35 bands, 1792 total dims). Common picks:

• Weather: weather.temperature_2m, weather.precipitation_mm,

weather.relative_humidity_2m, weather.wind_speed_10m

• Air quality: cams.pm25, cams.no2, cams.aod_550
• Climate: era5.t2m, era5.precip (1940→present hourly)
• Vegetation: indices.ndvi, indices.evi, modis.ndvi_mean
• Elevation: copdem30m.elevation_mean, gmrt.topobathy_mean
• Land cover: esa_worldcover.lc_2021
• Embeddings: geotessera (128-D, default 2024 vintage); the

responder also ships geotessera.{2017..2024} for per-year and geotessera.multi_year (1024-D = 8×128 stacked).

If unsure which band fits the user's question, call /v1/bands and filter by family (weather, vegetation, terrain, landcover, climate).

Recovering from errors

• HTTP 404 `cid_not_found` — band has no fact at this cell on

this responder. With EMEM_AUTO_MATERIALIZE=on (default at emem.dev) the recall already attempted to materialise; the band has no upstream connector wired. Use /v1/data_availability to check which bands have a materialiser.

• HTTP 400 `unknown cell64 symbol` — typo in the cell64. Re-run

step 1 with the place name.

• HTTP 422 — request body malformed; the responder's structured

error message names the missing field.

Verifying offline

Pass the returned receipt to the emem-verify-receipt skill (or to POST /v1/verify_receipt server-side) to confirm the signature without re-trusting the responder.

Worked example

USER: What's the current temperature in Bengaluru, and the NDVI?

CLAUDE invokes this skill:
  POST /v1/locate {"q":"Bengaluru, India"}
    → cell64=defi.zb493.xoso.zcb6a
  POST /v1/recall {"cell":"defi.zb493.xoso.zcb6a",
                   "bands":["weather.temperature_2m","indices.ndvi"]}
    → facts:
       weather.temperature_2m = 28.4 degC
       indices.ndvi = 0.42
    → fact_cids: [qi3jo4..., bn7c4d...]

CLAUDE replies: "Bengaluru is at 28.4 °C right now (signed by
emem.dev at 2026-05-08T13:22Z). The vegetation index there
is 0.42 — middling, consistent with a dry urban core. Both
facts are content-addressed: qi3jo4...l2hgjtwm and
bn7c4d...kkb73a respectively."