tools: obf_runs and obf_kinds, measuring the obfuscated subjects

obf_runs: how obfuscated articles come in runs (strict, and per poster
and tool with a time gap). obf_kinds: what they are (unquoted subjects
with a counter, random tokens equal to the message-id, other random
tokens, ...), with examples. LOG.md 2026-10-11 (5).

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

tools/obf_kinds.ts

@@ -0,0 +1,43 @@
+/**
+ * What the obfuscated lines of a capture are (LOG.md 2026-10-11 (5)):
+ * unquoted subjects with a counter ("Name.exe (1/2)", parseable without
+ * quotes), random tokens equal to the message-id's local part (ngPost-style
+ * private uploads), other random tokens, and the rest; with examples.
+ *
+ *   node --import=@poppinss/ts-exec tools/obf_kinds.ts <capture dir>...
+ */
+import { readFile, readdir } from 'node:fs/promises'
+import { join } from 'node:path'
+import { unzipSync } from 'node:zlib'
+import { SegmentScanner, scanOverviewText } from '#lib/edge/scan'
+
+for (const dir of process.argv.slice(2)) {
+  const { group } = JSON.parse(await readFile(join(dir, 'range.json'), 'utf8'))
+  const scanner = new SegmentScanner()
+  const kinds = new Map<string, { n: number; examples: string[] }>()
+  let obfuscated = 0
+  const add = (kind: string, subject: string) => {
+    const k = kinds.get(kind) ?? { n: 0, examples: [] }
+    k.n++
+    if (k.examples.length < 3) k.examples.push(subject.slice(0, 90))
+    kinds.set(kind, k)
+  }
+  for (const file of (await readdir(dir)).filter((f) => f.endsWith('.gz')).sort()) {
+    scanOverviewText(unzipSync(await readFile(join(dir, file))).toString('utf8'), (n, subject, from, date, messageId, bytes, xref) => {
+      if (xref && scanner.owner(xref, group, { [group]: 1 }) !== group) return
+      if (scanner.segment(n, subject, from, date, messageId, bytes, xref, group)) return
+      obfuscated++
+      const local = messageId.replace(/^</, '').split('@')[0]
+      const s = subject.trim()
+      if (/\(\d+\/\d+\)\s*$/.test(s) || /\[\d+\/\d+\]\s*$/.test(s)) add(/"/.test(s) ? 'counter, quoted name not parsed' : 'counter, unquoted name', s)
+      else if (s === local) add('random = message-id', s)
+      else if (/^[A-Za-z0-9]{16,}$/.test(s)) add('random token', s)
+      else if (/yEnc/i.test(s)) add('yEnc, no counter', s)
+      else add('other', s)
+    })
+  }
+  console.log(`== ${dir}: ${obfuscated} obfuscated`)
+  for (const [kind, k] of [...kinds].sort((a, b) => b[1].n - a[1].n)) {
+    console.log(`  ${kind}: ${k.n} (${((100 * k.n) / obfuscated).toFixed(1)}%)  e.g. ${k.examples.map((e) => JSON.stringify(e)).join(' | ')}`)
+  }
+}