Prober: a flush with a NUL in a name, or one article twice, no longer fails

jsonb can't hold \u0000, and ON CONFLICT can't take a row twice in one
statement: either failed the whole flush, its outcomes lost and its
candidates taken until a restart. NULs are dropped from strings; the
probe_cache insert takes each message-id once.

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

app/services/prober.ts

@@ -30,6 +30,15 @@ const TIERS: { kind: string; unreadable: boolean }[] = [
   { kind: 'archive', unreadable: false },
 ]
 const FLUSH_MS = 2000
+
+/**
+ * JSON for a jsonb parameter, without NUL characters: jsonb can't hold \u0000 (a name read from an article had one),
+ * and the whole flush failed with it (LOG.md 2026-10-18 (78)).
+ */
+function jsonb(value: unknown): string {
+  return JSON.stringify(value, (_key, v) => (typeof v === 'string' ? v.replaceAll('\0', '') : v))
+}
+
 /** Slices a claim takes from random points of the queue. */
 const SLICES = 20
 const REPORT_MS = 60_000
@@ -262,16 +271,18 @@ export class Prober {
     await db.transaction(async (trx) => {
       await trx.rawQuery(
         `UPDATE probe_candidates pc SET status = v.status FROM jsonb_to_recordset(?::jsonb) AS v(id bigint, status text) WHERE pc.id = v.id`,
-        [JSON.stringify(outcomes.map((o) => ({ id: o.candidate.id, status: o.status })))]
+        [jsonb(outcomes.map((o) => ({ id: o.candidate.id, status: o.status })))]
       )
       // Final answers read from the news server, kept by message-id for the next catalog (a reset).
-      const fresh = outcomes.filter((o) => !o.cached && o.status !== 'waiting')
+      // One per message-id: the same article is a candidate of more than one release, and ON CONFLICT can't take a
+      // row twice in one statement.
+      const fresh = [...new Map(outcomes.filter((o) => !o.cached && o.status !== 'waiting').map((o) => [o.candidate.messageId, o])).values()]
       if (fresh.length > 0) {
         await trx.rawQuery(
           `INSERT INTO probe_cache (message_id, status, result, version)
            SELECT v.message_id, v.status, v.result, ? FROM jsonb_to_recordset(?::jsonb) AS v(message_id text, status text, result jsonb)
            ON CONFLICT (message_id) DO UPDATE SET status = excluded.status, result = excluded.result, version = excluded.version, created_at = now()`,
-          [PROBE_VERSION, JSON.stringify(fresh.map((o) => ({ message_id: o.candidate.messageId, status: o.status, result: o.inspection ?? null })))]
+          [PROBE_VERSION, jsonb(fresh.map((o) => ({ message_id: o.candidate.messageId, status: o.status, result: o.inspection ?? null })))]
         )
       }
       const done = outcomes.filter((o) => o.inspection)
@@ -281,7 +292,7 @@ export class Prober {
          SELECT v.release_id, v.candidate_id, v.kind, v.result FROM jsonb_to_recordset(?::jsonb) AS v(release_id bigint, candidate_id bigint, kind text, result jsonb)
          ON CONFLICT (release_id, candidate_id) DO UPDATE SET result = excluded.result, created_at = now()`,
         // A par2 set's file list goes to par2_files, not into every inspection.
-        [JSON.stringify(done.map((o) => ({ release_id: o.candidate.releaseId, candidate_id: o.candidate.id, kind: o.candidate.kind, result: { ...o.inspection, par2: undefined } })))]
+        [jsonb(done.map((o) => ({ release_id: o.candidate.releaseId, candidate_id: o.candidate.id, kind: o.candidate.kind, result: { ...o.inspection, par2: undefined } })))]
       )
       await this.storeForMerge(trx, done)
       // Each touched release from all its inspections (earlier rounds may have stored others).
@@ -305,7 +316,7 @@ export class Prober {
       await trx.rawQuery(
         `UPDATE releases r SET passworded = v.passworded, inner_name = v.inner_name, inspected_at = now()
          FROM jsonb_to_recordset(?::jsonb) AS v(id bigint, passworded boolean, inner_name text) WHERE r.id = v.id`,
-        [JSON.stringify(updates)]
+        [jsonb(updates)]
       )
     })
   }
@@ -318,7 +329,7 @@ export class Prober {
         `INSERT INTO file_hashes (candidate_id, release_id, hash16k, size)
          SELECT v.candidate_id, v.release_id, v.hash16k, v.size FROM jsonb_to_recordset(?::jsonb) AS v(candidate_id bigint, release_id bigint, hash16k text, size bigint)
          ON CONFLICT (candidate_id) DO NOTHING`,
-        [JSON.stringify(hashed.map((o) => ({ candidate_id: o.candidate.id, release_id: o.candidate.releaseId, hash16k: o.inspection!.hash16k, size: o.inspection!.size })))]
+        [jsonb(hashed.map((o) => ({ candidate_id: o.candidate.id, release_id: o.candidate.releaseId, hash16k: o.inspection!.hash16k, size: o.inspection!.size })))]
       )
     }
     for (const o of done) {
@@ -328,7 +339,7 @@ export class Prober {
         `INSERT INTO par2_files (set_id, file_id, hash16k, length, name)
          SELECT ?, v.file_id, v.hash16k, v.length, v.name FROM jsonb_to_recordset(?::jsonb) AS v(file_id text, hash16k text, length bigint, name text)
          ON CONFLICT DO NOTHING`,
-        [set.setId, JSON.stringify(set.files.map((f) => ({ file_id: f.fileId, hash16k: f.hash16k, length: f.length, name: f.name })))]
+        [set.setId, jsonb(set.files.map((f) => ({ file_id: f.fileId, hash16k: f.hash16k, length: f.length, name: f.name })))]
       )
       await trx.rawQuery(`INSERT INTO par2_sets (set_id, release_id, files) VALUES (?, ?, ?) ON CONFLICT DO NOTHING`, [set.setId, o.candidate.releaseId, set.files.length])
     }