feat: add diagnostic endpoint, CORS proxy, step logging for Scottish Water

Agent-Logs-Url: https://github.com/JonnyDawe/UK-Sewage-Map/sessions/271da0ab-4bc2-4a85-bbd2-5f6dcbb655ec

Author: Copilot

api/debug-scottish-water.ts

@@ -0,0 +1,132 @@
+/**
+ * Diagnostic endpoint for the Scottish Water API integration.
+ *
+ * Accessible at /api/debug-scottish-water — returns a structured JSON report of
+ * every step in the fetch → parse → validate pipeline so failures can be identified
+ * without needing access to a browser console.
+ */
+
+import { z } from 'zod';
+
+export const config = {
+  runtime: 'edge',
+};
+
+const SCOTTISH_WATER_API_URL =
+  'https://api.scottishwater.co.uk/overflow-event-monitoring/v1/near-real-time';
+
+// Mirror of the schema in src/utils/discharge/schemas.ts
+const emptyStringToNull = (val: unknown) => (val === '' ? null : val);
+
+const scottishWaterApiResultSchema = z.object({
+  ASSET_ID: z.string().max(256).nullable(),
+  ASSET_NAME: z.string().max(256).nullable(),
+  OVERFLOW_STATUS_ID: z.preprocess(emptyStringToNull, z.coerce.number().nullable()),
+  RECEIVING_WATER: z.string().max(256).nullable(),
+  OVERFLOW_START_DATETIME: z.string().nullable(),
+  OVERFLOW_END_DATETIME: z.string().nullable(),
+  DISCHARGE_OVERFLOW_LOCATION_LATITUDE: z.preprocess(
+    emptyStringToNull,
+    z.coerce.number().nullable(),
+  ),
+  DISCHARGE_OVERFLOW_LOCATION_LONGITUDE: z.preprocess(
+    emptyStringToNull,
+    z.coerce.number().nullable(),
+  ),
+});
+
+const scottishWaterApiResponseSchema = z.object({
+  results: z.array(scottishWaterApiResultSchema),
+});
+
+export default async function handler(): Promise<Response> {
+  const report: Record<string, unknown> = {};
+
+  // ── Step 1: fetch ────────────────────────────────────────────────────────
+  let rawText: string;
+  try {
+    const response = await fetch(SCOTTISH_WATER_API_URL);
+    report['step1_fetch'] = {
+      ok: response.ok,
+      status: response.status,
+      statusText: response.statusText,
+      contentType: response.headers.get('content-type'),
+    };
+
+    if (!response.ok) {
+      return json({ ...report, conclusion: `FAILED at step 1: HTTP ${response.status}` });
+    }
+
+    rawText = await response.text();
+    report['step2_raw_text'] = {
+      byteLength: rawText.length,
+      preview: rawText.slice(0, 500),
+    };
+  } catch (err) {
+    report['step1_fetch'] = {
+      ok: false,
+      error: String(err),
+      hint: 'fetch() threw — likely a network or CORS error from the edge function',
+    };
+    return json({ ...report, conclusion: 'FAILED at step 1: fetch threw an exception' });
+  }
+
+  // ── Step 2: JSON parse ───────────────────────────────────────────────────
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(rawText);
+    report['step3_json_parse'] = { ok: true };
+  } catch (err) {
+    report['step3_json_parse'] = { ok: false, error: String(err) };
+    return json({ ...report, conclusion: 'FAILED at step 3: response is not valid JSON' });
+  }
+
+  // ── Step 3: top-level shape ──────────────────────────────────────────────
+  const topLevelKeys =
+    parsed !== null && typeof parsed === 'object' ? Object.keys(parsed as object) : [];
+  report['step4_top_level_keys'] = topLevelKeys;
+
+  // ── Step 4: schema validation ────────────────────────────────────────────
+  const schemaResult = scottishWaterApiResponseSchema.safeParse(parsed);
+
+  if (!schemaResult.success) {
+    report['step5_schema_validation'] = {
+      ok: false,
+      errorCount: schemaResult.error.issues.length,
+      // Show up to 10 issues to keep the response readable
+      issues: schemaResult.error.issues.slice(0, 10),
+    };
+    return json({ ...report, conclusion: 'FAILED at step 5: Zod schema validation failed' });
+  }
+
+  const { results } = schemaResult.data;
+  report['step5_schema_validation'] = { ok: true, totalRecords: results.length };
+
+  // ── Step 5: coordinate filter ────────────────────────────────────────────
+  const withCoords = results.filter(
+    (r) =>
+      r.DISCHARGE_OVERFLOW_LOCATION_LATITUDE != null &&
+      r.DISCHARGE_OVERFLOW_LOCATION_LONGITUDE != null,
+  );
+  const withoutCoords = results.length - withCoords.length;
+
+  report['step6_coordinate_filter'] = {
+    recordsWithCoords: withCoords.length,
+    recordsDropped: withoutCoords,
+  };
+
+  if (withCoords.length === 0) {
+    return json({ ...report, conclusion: 'FAILED at step 6: no records have valid coordinates' });
+  }
+
+  // ── Step 6: sample parsed records ───────────────────────────────────────
+  report['step7_sample_records'] = withCoords.slice(0, 3);
+
+  return json({ ...report, conclusion: 'SUCCESS: all steps passed' });
+}
+
+function json(data: unknown): Response {
+  return new Response(JSON.stringify(data, null, 2), {
+    headers: { 'Content-Type': 'application/json' },
+  });
+}

api/scottish-water.ts

@@ -16,7 +16,8 @@ export default async function handler(): Promise<Response> {
         'Cache-Control': 'public, max-age=60, s-maxage=60',
       },
     });
-  } catch {
+  } catch (err) {
+    console.error('[ScottishWater] Proxy fetch failed:', err);
     return new Response(JSON.stringify({ error: 'Failed to fetch data from Scottish Water API' }), {
       status: 500,
       headers: { 'Content-Type': 'application/json' },

src/components/Map/commands/AddDischargeSources/AddDischargeSourcesCommand.ts

@@ -146,7 +146,12 @@ export class AddDischargeSourcesCommand implements MapCommand {
     console.log(`[ScottishWater] Step 4: ${validated.results.length} records from API`);
 
     const withCoords = validated.results.filter(
-      (item) =>
+      (
+        item,
+      ): item is typeof item & {
+        DISCHARGE_OVERFLOW_LOCATION_LATITUDE: number;
+        DISCHARGE_OVERFLOW_LOCATION_LONGITUDE: number;
+      } =>
         item.DISCHARGE_OVERFLOW_LOCATION_LATITUDE != null &&
         item.DISCHARGE_OVERFLOW_LOCATION_LONGITUDE != null,
     );
@@ -166,8 +171,8 @@ export class AddDischargeSourcesCommand implements MapCommand {
       (item, index) =>
         new Graphic({
           geometry: new Point({
-            longitude: item.DISCHARGE_OVERFLOW_LOCATION_LONGITUDE!,
-            latitude: item.DISCHARGE_OVERFLOW_LOCATION_LATITUDE!,
+            longitude: item.DISCHARGE_OVERFLOW_LOCATION_LONGITUDE,
+            latitude: item.DISCHARGE_OVERFLOW_LOCATION_LATITUDE,
             spatialReference: { wkid: 4326 },
           }),
           attributes: {