Maffeo da Treviglio at Buda to Ludovico Sforza, 1489–1490

TASK: take a partial decipherment further: Maffeo da Treviglio at Buda to Ludovico Sforza, 1489–1490
This page: https://dbourdeau.github.io/cyphersolver/further/buda1489.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/buda1489.html (read it first: how the text was read, the key, the reading)
  Date:       1489–90
  Outcome:    known key applied · partial
  Read now:   56.0% of the deciphered cipher tokens give sense (pieces below may be untouched)
  Files:      https://github.com/dbourdeau/cyphersolver/tree/main/targets/buda1489 (NOTES.md, key, transcription, reading, scripts)

OPEN GAPS (from NOTES.md, "## Remaining gaps")
  1. [no-key-material: needs a new source] 2831 letter groups that decode letter for letter but give no word: p. 1 L03, L04, L08, L11, L12, L17, L19-L22, L25-L29; p. 2 L15, L16, L19-L21, L25, L28-L31 between secure words; p. 3 L02, L03 head, L05-L08 middles, L15, L18, L21, L22, L27, L29, L31; p. 4 L02 - blocker: no-key-material; four passes (b25 twice, r2e with R5411, r2l 23 Oct 2026 with the lang/ it-cinquecento segmenter over every alternative sign value and a full-resolution p. 3 re-crop); they need the values of the torn R5411 columns (T, U/V, X, Y, Z, &) or of signs not in the key (r-ring, the n-stroke in 'ochi aperti', the lone x on p. 3 l. 29)
  2. [illegible: needs a new source] 2831 p. 3 l. 15, signs under an ink blot - blocker: illegible
  3. [illegible: needs a new source] 2831 p. 1 ll. 21–29, last words of each line - blocker: illegible; stain at the right edge, no other image (DECODE and Vestigia serve the same negative); re-checked at 3x 23 Oct 2026 (r2e)
  4. [no-key-material: needs a new source] signs in the torn columns of R5411 (x, y, z, &, part of t), r-ring on p. 3 l. 15, and the o-form (b by the key, t in most words) - blocker: no-key-material; R5411 is torn at the upper right

ALREADY TRIED (from NOTES.md, "## Escalation")
  [x] siblings: Maffeo's and the embassy's letters in cart. 642/645/650 opened on Vestigia and DECODE: R1155 (clear copy Vestigia 2240), R1147 (Vestigia 603, Labancz no. 45), R1152 (clear draft), R1146 and R1158 (other ciphers); no clear copy of 2831 or R1098 exists among them
  [x] clear-pages: R1098 p. 2 is clear and restates cipher ll. 7–10 (used as a control); 2831 p. 4 ll. 3–17 are a clear postscript; Somogyi's five cipher/clear pairs located, 267/268 used for calibration
  [x] known-keys: Somogyi's 2016 key used first; 23 Oct 2026 the original key found, ASMi Sforzesco cart. 1597 no. 111 (DECODE R5411, key_R5411.md), and used for p. 2 ll. 17-30 and p. 3; the abbot of Forlì's cipher (R1146/R1147) is a different system
  [x] print: Somogyi 2016 (prints only 2831 ll. 1–2) and Labancz's 1491 edition checked; Nagy and Nyáry, MDE IV (1878): R1098 is printed as no. 91 (contemporary extract), 2831 is not in it (search of 9 Oct 2026 recorded in the main checkout's uncommitted NOTES); Vestigia 2831 lists no publication
  [x] key-rebuild: about twenty sign values beyond Somogyi's table recovered from the unread letters by single-word cribs (7 = f, n+crossed 4 = ss, x' = do, a: = gli, q^o = re, b^a = na)
  [x] retry: 23 Oct 2026 (b25) p. 2 ll. 17-30 and p. 3 re-read sign by sign from the plates, twice (Somogyi's values, then R5411); 23 Oct 2026 (v3) R1098 ll. 5-10 re-read with R5411 and aligned with MDE IV no. 91; 23 Oct 2026 (r2e) p. 1, p. 2 ll. 1-17 and p. 4 re-read sign by sign with R5411 (read, 0.642) and a third pass on b25's p. 2 lines; 23 Oct 2026 (r2l) fourth pass: the unread groups segmented with the lang/ it-cinquecento model over every alternative sign value, p. 3 re-cropped at full resolution (p. 2 ll. 18-31 and p. 3 read, 0.636); 23 Oct 2026 (sr) independent second reader on 8 random lines: signs 93.3%, words not carried 9.8% after re-crop (kept read)

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/buda1489/NOTES.md in full, and the
   key, transcription and reading files it names; lang/README.md (shared language models).
   Work in targets/buda1489/. 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/buda1489/. 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+buda1489&page=buda1489.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.