Lone articles under scrambled names are per-article; inactive groups get no corpus fill

One article of a multi-part file under a name like "nYDeXeF49dieZ1J7flK-JFzZ3j.ZEDsr" or
"bslXlwgPiqZadhRa" (a random subject and poster per article, with fake counters) was a release:
looksRandom misses these names for their separators. 160k of alt.binaries.storage's 162k
non-Bob releases, and about 60% of all single-article releases in a 2% sample.

looks_scrambled / isScrambledFile: at least half the stem's letters and digits in tokens of 5+
that switch case or letter/digit 3 times or more (93% of the storage spam). Used for lone
articles given up before the block's end only; at the end the strict looksRandom stays, as the
rest of such a file can be in the next block. The namer's re-index (partialFiles) does the same.

The prefetcher's corpus fill skips groups that aren't active.

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

edge/src/indexer.rs

@@ -5,7 +5,7 @@
 
 use crate::codec::{encode_chunk, ChunkFile};
 use crate::js::{self, sha1_hex};
-use crate::names::{self, is_random_file, JudgedFile, Release, Rules, Verdict};
+use crate::names::{self, is_random_file, looks_scrambled, JudgedFile, Release, Rules, Verdict};
 use rustc_hash::{FxHashMap, FxHashSet};
 use serde::{Deserialize, Serialize};
 use std::rc::Rc;
@@ -1176,11 +1176,11 @@ impl RangeIndexer {
         let t = std::time::Instant::now();
         let done = self.aggregator.add(segments);
         unsafe { PROF[3] += t.elapsed().as_nanos() as u64; }
-        self.files(done);
+        self.files(done, false);
         self.frontier.update();
         let t = std::time::Instant::now();
         let gone = self.aggregator.evict(self.frontier.closed_before(), self.idle, false);
-        self.files(gone);
+        self.files(gone, false);
         self.close(false);
         unsafe { PROF[4] += t.elapsed().as_nanos() as u64; }
         self.batch.next = next;
@@ -1191,7 +1191,7 @@ impl RangeIndexer {
     pub fn finish(&mut self) {
         self.frontier.settle();
         let gone = self.aggregator.evict(None, 0, true);
-        self.files(gone);
+        self.files(gone, true);
         self.close(true);
         self.batch.next = self.end + 1;
     }
@@ -1243,12 +1243,16 @@ impl RangeIndexer {
         out
     }
 
-    /// Finished files (complete, or the window closed on them) into the open release of their key and upload.
-    fn files(&mut self, files: Vec<Vec<Seg>>) {
+    /// Finished files (complete, or the window closed on them) into the open release of their key and upload; `at_end`
+    /// when the block ends on them.
+    fn files(&mut self, files: Vec<Vec<Seg>>, at_end: bool) {
         let batch = self.aggregator.batch;
         for file in files {
-            if file.len() == 1 && (file[0].number != 1 || file[0].file.total_parts > 1) && is_random_file(&file[0].file.name) {
-                // One article of a multi-part random file (its upload per article: ngPost's, nyuu's): not a release.
+            let lone = file.len() == 1 && (file[0].number != 1 || file[0].file.total_parts > 1);
+            // A scrambled name only before the block's end, where the rest of a file can still be in the next block.
+            if lone && (is_random_file(&file[0].file.name) || (!at_end && looks_scrambled(&file[0].file.name))) {
+                // One article of a multi-part random file (its upload per article: ngPost's, nyuu's, and a random poster's
+                // per article, 160k in alt.binaries.storage; LOG.md (122)): not a release.
                 let tool = names::upload_tool(&file[0].message_id);
                 self.count("per-article", tool.to_string(), 1, 0);
                 continue;