Seed relay: compressed overviews by default again

Measured with 20 relay connections, plain and gzip both gave ~1.5 chunks/s
for 2026 a.b.ath articles; plain used many times the CPU and traffic.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/services/SeedFetchPool.ts

@@ -31,8 +31,7 @@ class SeedFetchPool {
   }
 
   /**
-   * Pooled connections fetch compressed only with SEED_NNTP_COMPRESS (plain is
-   * faster for recent articles). A failure is retried once without compression, on a connection of its
+   * Pooled connections fetch compressed unless SEED_NNTP_COMPRESS=false. A failure is retried once without compression, on a connection of its
    * own: either the pooled connection was dead (dropped while idle), or the
    * server stalled mid-reply in compressed mode. Eweka does that for some
    * chunks: it stops after most of the stream and never sends the rest

config/indexer.ts

@@ -73,11 +73,12 @@ export default {
      */
     nntpTimeoutMs: env.get('SEED_NNTP_TIMEOUT_MS', 90 * 1000),
     /**
-     * Ask the news server for gzip-compressed overviews. Off: for 2026 articles Eweka's
-     * compressed replies have a long tail (p90 12.4 s per 20k, against 3.9 s plain; 6.1k
-     * against 10.5k headers/s, LOG.md 2026-10-06 (9)). Nodes get gzip from the relay either way.
+     * Ask the news server for gzip-compressed overviews (SEED_NNTP_COMPRESS=false: plain).
+     * On one connection plain had a shorter tail for 2026 articles, but with 20 relay
+     * connections both gave ~1.5 chunks/s, plain at many times the relay's CPU and
+     * more traffic (LOG.md 2026-10-06 (9)).
      */
-    nntpCompress: env.get('SEED_NNTP_COMPRESS', false),
+    nntpCompress: env.get('SEED_NNTP_COMPRESS', true),
   },
 
   backfill: {

tests/unit/seed_fetch_pool.spec.ts

@@ -27,7 +27,7 @@ test.group('SeedFetchPool', () => {
     })
     await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve))
     const saved = { host: nntpConfig.host, port: nntpConfig.port, secure: nntpConfig.secure, connections: indexerConfig.seed.nntpConnections, compress: indexerConfig.seed.nntpCompress }
-    // The fallback from a compressed pooled connection (SEED_NNTP_COMPRESS on).
+    // The fallback from a compressed pooled connection (the default).
     indexerConfig.seed.nntpCompress = true
     Object.assign(nntpConfig, { host: '127.0.0.1', port: (server.address() as net.AddressInfo).port, secure: false })
     indexerConfig.seed.nntpConnections = 2