fix(seeds): add empty-data guards and fix health semantics (#1767)

Health semantics:
- Add faaDelays + gpsjam to EMPTY_DATA_OK_KEYS (0 records = calm, not error)
- Fix EMPTY_DATA_OK_KEYS branch to still check seed-meta freshness
  (prevents stale empty caches from staying green indefinitely)

Seed guards:
- seed-airport-delays: fix meta key in fetch-failure path
  (seed-meta:aviation:delays -> seed-meta:aviation:faa + seed-meta:aviation:notam)
- seed-military-flights: add full TTL extension on zero-flights branch
  (was exiting without preserving any derived data TTLs)
- seed-wb-indicators: add percentage-drop guard (new count < 50% of cached
  = likely partial API failure, extend TTL instead of overwriting)
- ais-relay.cjs: same percentage-drop guard for WB dual writer

Codex-reviewed plan (5 rounds, approved).

api/health.js

@@ -151,7 +151,7 @@ const ON_DEMAND_KEYS = new Set([
 
 // Keys where 0 records is a valid healthy state (e.g. no airports closed).
 // The key must still exist in Redis; only the record count can be 0.
-const EMPTY_DATA_OK_KEYS = new Set(['notamClosures']);
+const EMPTY_DATA_OK_KEYS = new Set(['notamClosures', 'faaDelays', 'gpsjam']);
 
 // Cascade groups: if any key in the group has data, all empty siblings are OK.
 // Theater posture uses live → stale → backup fallback chain.
@@ -333,9 +333,14 @@ export default async function handler(req) {
       if (cascadeCovered) {
         status = 'OK_CASCADE';
         okCount++;
-      } else if (EMPTY_DATA_OK_KEYS.has(name) && seedStale === false) {
-        status = 'OK';
-        okCount++;
+      } else if (EMPTY_DATA_OK_KEYS.has(name)) {
+        if (seedStale === true) {
+          status = 'STALE_SEED';
+          warnCount++;
+        } else {
+          status = 'OK';
+          okCount++;
+        }
       } else if (isOnDemand) {
         status = 'EMPTY_ON_DEMAND';
         warnCount++;
@@ -348,8 +353,13 @@ export default async function handler(req) {
         status = 'OK_CASCADE';
         okCount++;
       } else if (EMPTY_DATA_OK_KEYS.has(name)) {
-        status = 'OK';
-        okCount++;
+        if (seedStale === true) {
+          status = 'STALE_SEED';
+          warnCount++;
+        } else {
+          status = 'OK';
+          okCount++;
+        }
       } else if (isOnDemand) {
         status = 'EMPTY_ON_DEMAND';
         warnCount++;

scripts/ais-relay.cjs

@@ -3692,6 +3692,19 @@ async function seedWorldBank() {
       return;
     }
 
+    // Percentage-drop guard: if new count < 50% of prior count, skip overwrite
+    try {
+      const priorMeta = await upstashGet(`seed-meta:${WB_BOOTSTRAP_KEY}`);
+      if (priorMeta && typeof priorMeta.recordCount === 'number' && priorMeta.recordCount > 0) {
+        if (rankings.length < priorMeta.recordCount * 0.5) {
+          console.warn(`[WB] Rankings dropped >50%: ${rankings.length} vs prior ${priorMeta.recordCount} — skipping overwrite`);
+          return;
+        }
+      }
+    } catch (e) {
+      console.warn('[WB] Percentage-drop guard failed (proceeding):', e?.message);
+    }
+
     const metaTtl = WB_TTL_SECONDS + 3600;
     let ok = await upstashSet(WB_BOOTSTRAP_KEY, rankings, WB_TTL_SECONDS);
     console.log(`[WB] techReadiness: ${rankings.length} rankings (redis: ${ok ? 'OK' : 'FAIL'})`);

scripts/seed-airport-delays.mjs

@@ -274,7 +274,7 @@ async function main() {
   } catch (err) {
     await releaseLock('aviation:delays', runId);
     console.error(`  FETCH FAILED: ${err.message || err}`);
-    await extendExistingTtl([FAA_CACHE_KEY, NOTAM_CACHE_KEY, 'seed-meta:aviation:delays'], CACHE_TTL);
+    await extendExistingTtl([FAA_CACHE_KEY, NOTAM_CACHE_KEY, 'seed-meta:aviation:faa', 'seed-meta:aviation:notam'], CACHE_TTL);
     console.log(`\n=== Failed gracefully (${Math.round(Date.now() - startMs)}ms) ===`);
     process.exit(0);
   }

scripts/seed-military-flights.mjs

@@ -1319,7 +1319,13 @@ async function main() {
   }
 
   if (flights.length === 0) {
-    console.log('  SKIPPED: 0 military flights — preserving stale data');
+    console.log('  SKIPPED: 0 military flights — extending existing TTLs');
+    await extendExistingTtl([LIVE_KEY, 'seed-meta:military:flights'], LIVE_TTL);
+    await extendExistingTtl([STALE_KEY, THEATER_POSTURE_STALE_KEY, MILITARY_SURGES_STALE_KEY, MILITARY_FORECAST_INPUTS_STALE_KEY, MILITARY_CLASSIFICATION_AUDIT_STALE_KEY], STALE_TTL);
+    await extendExistingTtl([THEATER_POSTURE_LIVE_KEY, MILITARY_FORECAST_INPUTS_LIVE_KEY, MILITARY_CLASSIFICATION_AUDIT_LIVE_KEY], THEATER_POSTURE_LIVE_TTL);
+    await extendExistingTtl([THEATER_POSTURE_BACKUP_KEY], THEATER_POSTURE_BACKUP_TTL);
+    await extendExistingTtl([MILITARY_SURGES_LIVE_KEY], MILITARY_SURGES_LIVE_TTL);
+    await extendExistingTtl(['seed-meta:theater-posture', 'seed-meta:military-forecast-inputs', 'seed-meta:military-surges'], STALE_TTL);
     await releaseLock('military:flights', runId);
     lockReleased = true;
     process.exit(0);

scripts/seed-wb-indicators.mjs

@@ -441,6 +441,32 @@ async function main() {
     process.exit(1);
   }
 
+  // Percentage-drop guard: if new count < 50% of prior count, extend TTLs instead of overwriting
+  try {
+    const priorMetaResp = await redisPipeline(redisUrl, redisToken, [
+      ['GET', `seed-meta:${BOOTSTRAP_KEY}`],
+    ]);
+    const priorMeta = priorMetaResp[0]?.result ? JSON.parse(priorMetaResp[0].result) : null;
+    if (priorMeta && typeof priorMeta.recordCount === 'number' && priorMeta.recordCount > 0) {
+      if (rankings.length < priorMeta.recordCount * 0.5) {
+        console.warn(`Rankings dropped >50%: ${rankings.length} vs prior ${priorMeta.recordCount} — extending TTLs instead of overwriting.`);
+        const extendPipeline = [
+          ['EXPIRE', fullKey, String(TTL_SECONDS)],
+          ['EXPIRE', `seed-meta:${BOOTSTRAP_KEY}`, String(TTL_SECONDS + 3600)],
+          ['EXPIRE', progressKey, String(TTL_SECONDS)],
+          ['EXPIRE', `seed-meta:${PROGRESS_KEY}`, String(TTL_SECONDS + 3600)],
+          ['EXPIRE', renewableKey, String(TTL_SECONDS)],
+          ['EXPIRE', `seed-meta:${RENEWABLE_KEY}`, String(TTL_SECONDS + 3600)],
+        ];
+        await redisPipeline(redisUrl, redisToken, extendPipeline);
+        console.log('TTLs extended. Exiting without overwriting.');
+        process.exit(0);
+      }
+    }
+  } catch (err) {
+    console.warn(`Percentage-drop guard failed (proceeding with write): ${err.message}`);
+  }
+
   // Write all keys + seed-meta to Redis in one pipeline
   const metaTtl = String(TTL_SECONDS + 3600); // seed-meta outlives data by 1h
   const pipeline = [