Fix dataset prefix matching in STAC server

README.md

@@ -120,6 +120,35 @@ const [finalized, metadata] = await client.loadDataset({
 
 ```
 
+### ERA5 land datasets
+
+ERA5 and ERA5-Land datasets are separate dataset IDs within the ECMWF ERA5 collection. Use `listAvailableDatasets()` to inspect the exact names before loading.
+
+```typescript
+// Non-land ERA5 total precipitation
+const [precipitation, precipitationMetadata] = await client.loadDataset({
+  request: {
+    organization: "ecmwf",
+    collection: "era5",
+    dataset: "precipitation_total",
+    variant: "finalized"
+  }
+});
+
+// ERA5-Land total precipitation
+const [landPrecipitation, landPrecipitationMetadata] = await client.loadDataset({
+  request: {
+    organization: "ecmwf",
+    collection: "era5",
+    dataset: "precipitation_total_land",
+    variant: "finalized"
+  }
+});
+
+// ERA5-Land wind datasets follow the same pattern:
+// dataset: "wind_u_10m_land" or dataset: "wind_v_10m_land"
+```
+
 ### Selecting while loading
 
 ```typescript

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@dclimate/dclimate-client-js",
-  "version": "0.5.8",
+  "version": "0.5.9",
   "description": "JavaScript client for dClimate datasets using jaxray and IPFS stores",
   "type": "module",
   "main": "./dist/node/index.js",

src/stac/stac-server.ts

@@ -37,6 +37,33 @@ export interface ResolvedCidFromServer {
   variant: string;
 }
 
+function datasetIdFromItemId(
+  itemId: string,
+  collection: string
+): string | undefined {
+  const prefix = `${collection}-`;
+  const remainder = itemId.startsWith(prefix) ? itemId.slice(prefix.length) : itemId;
+  const [dataset] = remainder.split("-");
+  return dataset || undefined;
+}
+
+function featureMatchesDataset(
+  feature: StacServerItem,
+  collection: string,
+  dataset: string
+): boolean {
+  if (feature.collection && feature.collection !== collection) {
+    return false;
+  }
+
+  const datasetId = getStringProperty(feature.properties, "dclimate:dataset_id");
+  if (datasetId) {
+    return datasetId === dataset;
+  }
+
+  return datasetIdFromItemId(feature.id, collection) === dataset;
+}
+
 /**
  * Resolve dataset CID via STAC server /search API.
  *
@@ -75,9 +102,11 @@ export async function resolveCidFromStacServer(
   const data: StacServerSearchResponse = await response.json();
   const features = data.features || [];
 
-  // Filter to matching dataset (item ID pattern: {collection}-{dataset}-{variant})
-  const prefix = `${collection}-${dataset}`;
-  const matches = features.filter((f) => f.id.startsWith(prefix));
+  // Filter to the exact dataset. A prefix match would conflate datasets such
+  // as precipitation_total and precipitation_total_land.
+  const matches = features.filter((f) =>
+    featureMatchesDataset(f, collection, dataset)
+  );
 
   if (matches.length === 0) {
     throw new Error(`No items found for ${collection}/${dataset}`);

tests/stac-server.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it, beforeAll } from "vitest";
+import { afterEach, beforeAll, describe, expect, it, vi } from "vitest";
 import {
   resolveCidFromStacServer,
   resolveDatasetCidFromStacServer,
@@ -79,6 +79,136 @@ describe("STAC Server", () => {
     });
   });
 
+  describe("exact dataset matching", () => {
+    afterEach(() => {
+      vi.unstubAllGlobals();
+    });
+
+    function mockSearchResponse(features: unknown[]) {
+      vi.stubGlobal(
+        "fetch",
+        vi.fn(async () => ({
+          ok: true,
+          json: async () => ({
+            type: "FeatureCollection",
+            features,
+          }),
+          text: async () => "",
+        }))
+      );
+    }
+
+    it("does not resolve a base ERA5 dataset to a *_land prefix collision", async () => {
+      mockSearchResponse([
+        {
+          type: "Feature",
+          id: "ecmwf_era5-precipitation_total_land-finalized",
+          collection: "ecmwf_era5",
+          properties: {
+            "dclimate:dataset_id": "precipitation_total_land",
+            "dclimate:variant": "finalized",
+          },
+          assets: {
+            data: {
+              href: "ipfs://bafy-era5-land-precip-finalized",
+            },
+          },
+        },
+        {
+          type: "Feature",
+          id: "ecmwf_era5-precipitation_total-finalized",
+          collection: "ecmwf_era5",
+          properties: {
+            "dclimate:dataset_id": "precipitation_total",
+            "dclimate:variant": "finalized",
+          },
+          assets: {
+            data: {
+              href: "ipfs://bafy-era5-precip-finalized",
+            },
+          },
+        },
+      ]);
+
+      const result = await resolveCidFromStacServer(
+        "ecmwf_era5",
+        "precipitation_total",
+        "finalized",
+        "https://example.test"
+      );
+
+      expect(result.cid).toBe("bafy-era5-precip-finalized");
+    });
+
+    it("rejects a request when only a prefix-related land dataset exists", async () => {
+      mockSearchResponse([
+        {
+          type: "Feature",
+          id: "ecmwf_era5-wind_u_10m_land-finalized",
+          collection: "ecmwf_era5",
+          properties: {
+            "dclimate:dataset_id": "wind_u_10m_land",
+            "dclimate:variant": "finalized",
+          },
+          assets: {
+            data: {
+              href: "ipfs://bafy-era5-land-wind-u",
+            },
+          },
+        },
+      ]);
+
+      await expect(
+        resolveCidFromStacServer(
+          "ecmwf_era5",
+          "wind_u_10m",
+          "finalized",
+          "https://example.test"
+        )
+      ).rejects.toThrow(/No items found/);
+    });
+
+    it("keeps legacy item-id fallback exact", async () => {
+      mockSearchResponse([
+        {
+          type: "Feature",
+          id: "ecmwf_era5-temperature_2m_land-finalized",
+          collection: "ecmwf_era5",
+          properties: {
+            "dclimate:variant": "finalized",
+          },
+          assets: {
+            data: {
+              href: "ipfs://bafy-era5-land-t2m",
+            },
+          },
+        },
+        {
+          type: "Feature",
+          id: "ecmwf_era5-temperature_2m-finalized",
+          collection: "ecmwf_era5",
+          properties: {
+            "dclimate:variant": "finalized",
+          },
+          assets: {
+            data: {
+              href: "ipfs://bafy-era5-t2m",
+            },
+          },
+        },
+      ]);
+
+      const result = await resolveCidFromStacServer(
+        "ecmwf_era5",
+        "temperature_2m",
+        "finalized",
+        "https://example.test"
+      );
+
+      expect(result.cid).toBe("bafy-era5-t2m");
+    });
+  });
+
   describe("resolveCidFromStacServer", () => {
     it("returns CID as string without ipfs:// prefix", async () => {
       if (!serverAvailable || !availableDataset) {