Mayenne–Forget’s Cipher-1, 1585–86

TASK: take a partial decipherment further: Mayenne–Forget’s Cipher-1, 1585–86
This page: https://dbourdeau.github.io/cyphersolver/further/matignon1586.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/matignon1586.html (read it first: how the text was read, the key, the reading)
  Date:       1585–1586
  Outcome:    known key applied · partial
  Read now:   85.9% of the deciphered cipher tokens give sense (pieces below may be untouched)
  Files:      https://github.com/dbourdeau/cyphersolver/tree/main/targets/matignon1586 (NOTES.md, key, transcription, reading, scripts)

OPEN GAPS (from NOTES.md, "## Remaining gaps")
  1. [no-key-material: needs a new source] ff. 123r (0.41) and 124r (0.56) decoded, not read - blocker: no-key-material; three passes each on the images (labels re-cut figure by figure, a per-label atlas of the hand's 5,111 figures with cross-leaf classifiers, code values from other leaves tried): the remaining breaks fall on legible figures of their ordinary shapes, so they are the writer's omissions or slips and codes 16, 60, 66, 67, 101, 102 with no value anywhere; only a clear copy of the Marmande despatch or another letter in this hand using the same codes would settle them (none found on canvases 126-139)
  2. [no-key-material: needs a new source] f. 110: ll. 1-4, 8, 10, 14-16, 24-25, 36 and codes 45, 47 inside a leaf that reads at 0.70 - blocker: no-key-material; three passes; legible figures that no key value consistent with the leaf fits, and codes with no gloss; l. 1 corner illegible
  3. [no-key-material: needs a new source] code groups 16, 19, 23, 45, 47 (f. 110), 60, 67 (f. 124), 65, 99 (f. 196v), 101, 102, 103, 9, and the name code 98 - blocker: no-key-material; one to three contexts each, none in a clear copy (9 is two different words against the copies). Settled 22 Oct 2026: 64 = *quelque*, 62 = *peu*, 73 = *le Roy* on fr. 15571 f. 177 (its clear copy f. 176), 63 = *après* (f. 201's clear tail), `me` a null on f. 177

ALREADY TRIED (from NOTES.md, "## Escalation")
  [x] siblings: ff. 14/15 and 18/19 cribs used to re-derive and verify the key; f. 78v margin decipherment used as a control (`cribem.py`); ff. 196/201 aligned (57% identical figures; Brackx's joint alignment, #64); f. 125r clear letter read for context; canvases 128-139 round ff. 123-124 checked for a copy, none (Brackx, #71). The f. 18/19 crib completed through f. 20r (Brackx, #78). Not yet: ff. 91-92
  [x] clear-pages: **ff. 155-157 are the contemporary clear copies of ff. 143, 149v-150 and 154r-v** (Brackx, #70; checked here). f. 144 is a separate letter; f. 19 is the decipherment of f. 18; f. 125r is a clear letter
  [x] known-keys: Cipher-1 done (Tomokiyo's table, re-derived and verified on every Cipher-1 leaf); the Cipher-3 leaves and their key are matignon1586c3; the Cipher-2 leaves (ff. 218-219, fr. 15573 ff. 120, 385) are mayenne1586c2
  [x] print: BnF catalogue and literature searched 17 Sept 2026, no printed decipherment; Tomokiyo's cryptiana openings for ff. 143, 150, 154, "111" used as checks
  [x] key-rebuild: key re-derived from the ff. 14/15 and 18/19 cribs, confusable figures modelled as letter sets, code values such as 17 *car*, 25 *nous* and 52 *plustost* added from context and the crib; Brackx's letter sets and eleven code values from the clear copies (`key_contrib.json`); his per-leaf keys and codes 15, 34, 46, 51, 61, 73, 78, 82, 84 (`brackx2026/`, 22 Oct), merged here into one key (`key_cipher1.json`, union; pruning tried and dropped); 59 = argent from the f. 157r copy
  [x] retry: every Cipher-1 leaf re-transcribed in full and re-decoded by Brackx (issues #73, #77-#79, #83, 22 Oct 2026) and re-scored here with this project's decoder and a control (`brackx_validate.py`); every open code retried against the copies and by LM ranking (`code_lm_test.py`), 59 recovered

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/matignon1586/NOTES.md in full, and the
   key, transcription and reading files it names; lang/README.md (shared language models).
   Work in targets/matignon1586/. 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/matignon1586/. 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+matignon1586&page=matignon1586.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.