Mayenne–Forget’s Cipher-2, 1586

TASK: take a partial decipherment further: Mayenne–Forget’s Cipher-2, 1586
This page: https://dbourdeau.github.io/cyphersolver/further/mayenne1586c2.html

You are helping a public research project finish reading historical cipher letters. This one is read in part:
the key works, but some pieces are still open. Your job is to close one or more of the open gaps below.

THE READING
  Write-up:   https://dbourdeau.github.io/cyphersolver/mayenne1586c2.html (read it first: how the text was read, the key, the reading)
  Date:       1586
  Outcome:    known key applied · partial
  Read now:   40.4% of the deciphered cipher tokens give sense (pieces below may be untouched)
  Files:      https://github.com/dbourdeau/cyphersolver/tree/main/targets/mayenne1586c2 (NOTES.md, key, transcription, reading, scripts)

OPEN GAPS (from NOTES.md, "## Remaining gaps")
  1. [no-key-material: needs a new source] code signs without a value: f. 385 14, 15, 30, invT (probably *vostre majesté*), x?; ff. 218-219 dotted K, 15, 19, 30, 36, dotted 9, dotted E, dotted χ°, ∻; f. 120 13 kinds in 15 places - blocker: no-key-material; most occur once, and the deciphered Cipher-2 letters Burford aligned do not contain them
  2. [no-key-material: needs a new source] ff. 218-219: stretches that do not read (f. 218r ll. 10-12, 22, 25-26; f. 218v ll. 9-10, 21-22; f. 219r ll. 1-5, 12-17) - blocker: no-key-material; one AI reading pass calibrated at 74.8%; a voted second pass with Burford's sign sheet and image checks is the next step
  3. [no-key-material: needs a new source] f. 385: 36 short stretches not read, 41 doubtful words - blocker: no-key-material; misread signs, names and abbreviations; Burford's planned second image round not yet made
  4. [no-key-material: needs a new source] f. 120: short stretches and three values inferred in this letter only (ooo = *escus*, struck gg = *nous*, curled stroke = *o*) - blocker: no-key-material; no person has checked the transcription
  5. [not-attempted: doable now] fr. 15573 f. 120: decoded, not read - blocker: not-attempted; partial reading f120_harumi/f120_reading.md (b21, 23 Oct 2026: 0.50 / explicit holes 0.647); r c15-c19, c24-c31, v c03-c05 to re-read sign by sign on views 246-247 (its 12 code signs with no value are in the code-signs line above)
  6. [not-attempted: doable now] fr. 15573 f. 385: decoded, not read - blocker: not-attempted; normalised partial reading f385_burford/f385_reading.md (b21, 23 Oct 2026: 0.222); the v0.2 unread stretches need the signs re-read on views 752-753

ALREADY TRIED (from NOTES.md, "## Escalation")
  [x] siblings: Burford aligned six letters in Cipher-2 deciphered at the time (fr. 15573 ff. 7v-8r, 32r-33r, 97r, 103v-104r, 149r-150r) for code values; both contributors calibrated their readers on ff. 103v-104r
  [x] clear-pages: ff. 218r and 219r carry clear opening and closing (used for date and sender); no clear copy of any of the three is known; the superscript marks on f. 120r examined 23 Oct 2026 (b21): cipher signs, not glosses; f. 121v = cover of f. 120, to Villeroy
  [x] known-keys: Tomokiyo's Cipher-2 table; the Cipher-1 key (matignon1586) and Cipher-3 key (matignon1586c3) are different ciphers
  [x] print: Tomokiyo's cryptiana list and his f. 385 fragment (credited to Lasry); contributors' web, GitHub and Cryptoole searches found nothing else; Lasry to be asked about f. 385
  [x] key-rebuild: code values from the deciphered siblings (Burford); values inferred in context (Harumi-Matsuba); conflicts listed under "The key"
  [x] retry: by the contributors: f. 385 five voted passes and image rounds on every unresolved stretch (Burford v0.1-v0.2); ff. 218v-219r 197 disagreements with a Codex transcription rechecked on the images, 19 corrected (f. 218r not reviewed); f. 120 differences with Codex checked on the image, 9 corrected. A voted second pass on ff. 218-219 is still open (in the gaps)

STEPS
0. Set up. If you can run a shell, fork and clone the repository and work inside it:
     git clone https://github.com/dbourdeau/cyphersolver.git
   Then read, in this order: CONTRIBUTING.md (how a contribution is sent and credited); README.md, sections
   "Repository layout" and "Conventions" (how readings are measured and named); targets/mayenne1586c2/NOTES.md in full, and the
   key, transcription and reading files it names; lang/README.md (shared language models).
   Work in targets/mayenne1586c2/. Add your findings to NOTES.md under a dated heading without rewriting what is there, and
   update the "## Remaining gaps" line of every gap you close. Keep WORKLOG.md there: one dated line per step
   (hypothesis, value tried, solver run, crib, control), failures included. Do not edit docs/ (the site is generated).
   If you cannot run a shell, fetch the files from the links above and keep your work in files you send with the issue.
1. Pick a gap. Start with the ones marked "doable now" (open-codes, not-attempted, left-open): the images and the key
   are online, so they need only work. A gap marked "needs a new source" (no-key-material, too-short, illegible,
   needs-physical-access) can be closed only by something new: a key
   or a deciphered sibling found elsewhere, a better image, a printed edition or calendar, a photograph from the archive.
   For those, search for that material first, and say where you looked even when you find nothing.
2. Start from the existing key and transcription in the folder. Do not rebuild the key from scratch, and do not
   re-read parts that are already read unless you find an error in them.
3. For a code group or sign value: list every place the group occurs, show how each reads with the value you propose,
   and say what still does not fit. For a passage: re-read it at the image and give the folio and line. For a missing
   letter or leaf: say where it is held and how it can be reached.
4. Measure again. Apply the key to the whole text, write the reading file, and count the share of cipher tokens that
   give sense (not an estimate). The reading is "complete" only when (1) at least 95% of its cipher tokens give sense;
   (2) no gap is left untried; (3) every letter in it is covered; (4) what stays open is scattered code groups or names,
   or pieces blocked from outside. Otherwise it stays "partial": say which gaps are still open and why.
5. Be honest. Mark every uncertain word with [?], leave unread groups as their numbers or signs, and never fill a gap
   with a plausible guess. A gap retried and still open, with what was ruled out, is worth reporting.

REPORT BACK
With a clone: open a pull request with your changes to targets/mayenne1586c2/. Say in the description which gaps you worked on,
  the share read before and after, and how you want to be credited (name, initials or handle, and a link).
Without one: open an issue: https://github.com/dbourdeau/cyphersolver/issues/new?template=further-reading.yml&title=Further+reading%3A+mayenne1586c2&page=mayenne1586c2.html
  Give the write-up, the gap you worked on (its line in Remaining gaps, or the code group, folio and line), what you
  propose, the evidence (every occurrence, the images or sources), the share read before and after, your step log,
  and the tools and AI model you used.
If you cannot open issues or pull requests, write this report for your human to send. Credit goes to the person who sends it.