DRILL 2026-08-21 — FULL/EMPTY contrast on demo-hp. All hashes sha256, byte-for-byte.
Comparator positive control: one byte flipped at offset 500000 of binary-1mb.bin
(af -> 00) => sha256sum -c FAILED rc=1; original PASSED rc=0. Mutant discarded.

Planted fixture (5 files, incl. two UTF-8 Hungarian accented names):
  SENTINEL.txt                    0c23c8531214fe20cbc1ed177da22f51d65570c5aaedb39e380aa8d4d3e62991
  binary-1mb.bin                  725763bbe679b22d5c231a14083ff13155f475c028c22ade4623955b50a2a84a
  nested/őszibarack.md            a39ad6f623da67ac72f2e62a24245eef46c722c279ae89cd6b0c7c45afa6a4c4
  plain.txt                       07e91a985809fc96752f97cddcf6523b211bc607c81a5808befabe35573926f1
  árvíztűrő-tükörfúrógép.txt      0d6a22ec56acf61b8a80e73eb12cb223d607acaa3684acfcfa7c3e34ecdfabea
Name bytes (UTF-8 NFC):
  árvíztűrő-tükörfúrógép.txt = c3a1 72 76 c3ad 7a 74 c5b1 72 c591 2d 74 c3bc 6b c3b6 72 66 c3ba 72 c3b3 67 c3a9 70 2e747874
  őszibarack.md              = c591 73 7a 69 62 61 72 61 63 6b 2e 6d 64

                     | class      | data leg          | in unit | in offsite snap | checking folder | OFF-SITE restore | LOCAL restore
 calibre-web  FULL   | drive      | userdata files    |   n/a   | YES 5/5 ident.  | YES 5/5 ident.  | YES 5/5 ident.   | -
 calibre-web  FULL   | drive      | named volume      | YES 1.42MB | YES          | YES             | NO  (silent)     | -
 privatebin   FULL   | no-drive   | named volume      | YES 1.06MB | YES 5/5 ident.| YES 5/5 ident.  | REFUSED (false)  | YES 5/5 ident.
 opengist     EMPTY  | no-drive   | named volume      | YES 181KB skeleton | YES  | YES             | REFUSED (false)  | -

CONCLUSION: the unit and the off-site snapshot HOLD the data, verified by identity.
The off-site full restore has no named-volume leg at all; the local restore has one.