seed:node splits a batch the seed API finds too large

Dense recent a.b.ath ranges produced batches over the 64 MB body limit
(413). The node now posts such a batch in halves; only the second moves
the range's resume point.

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

commands/SeedNode.ts

@@ -301,6 +301,8 @@ export default class SeedNode extends BaseCommand {
     const started = Date.now()
     let headers = 0
     let chain: Promise<void> = Promise.resolve()
+    // Where the range resumes after what was stored: a batch split in two reports it with its first half.
+    let reported = lease.start
     const posting = new Set<Promise<void>>()
     // Throws once a post has failed, so the range stops fetching.
     const failedSoFar = () => Promise.race([chain, Promise.resolve()])
@@ -321,7 +323,8 @@ export default class SeedNode extends BaseCommand {
           if (this.stopping) throw new Stopping()
           while (posting.size >= 2) await Promise.race(posting)
           const post = chain.then(async () => {
-            await api.post(`/api/v1/seed/ranges/${lease.id}/batches`, batch)
+            await this.postBatch(api, lease.id, batch, reported)
+            reported = batch.next
             headers += batch.headers
           })
           chain = post
@@ -354,6 +357,26 @@ export default class SeedNode extends BaseCommand {
     }
   }
 
+  /**
+   * Posts a batch; one the seed API finds too large (413: dense recent ranges) is
+   * posted in two halves, at most three splits deep. Only the second half moves
+   * the range's resume point, so a failure in between loses nothing.
+   */
+  private async postBatch(api: SeedApi, rangeId: number, batch: SeedBatch, reported: number, depth = 0): Promise<void> {
+    try {
+      await api.post(`/api/v1/seed/ranges/${rangeId}/batches`, batch)
+    } catch (error: any) {
+      const parts = batch.files.length + batch.fragments.length
+      if (!/: 413 /.test(String(error.message)) || depth >= 3 || parts < 2) throw error
+      const files = Math.ceil(batch.files.length / 2)
+      const fragments = Math.ceil(batch.fragments.length / 2)
+      const first: SeedBatch = { ...batch, next: reported, headers: 0, obfuscated: 0, deferred: 0, files: batch.files.slice(0, files), fragments: batch.fragments.slice(0, fragments) }
+      const second: SeedBatch = { ...batch, files: batch.files.slice(files), fragments: batch.fragments.slice(fragments) }
+      await this.postBatch(api, rangeId, first, reported, depth + 1)
+      await this.postBatch(api, rangeId, second, reported, depth + 1)
+    }
+  }
+
   /** Sleeps, but wakes up early when the node is stopping. */
   private async pause(ms: number) {
     for (let waited = 0; waited < ms && !this.stopping; waited += 1000) await sleep(1000)