Maurice to Rupert, 1645, and the Digby-coach intercepts, 1646: still unread

TASK: take a partial decipherment further: Maurice to Rupert, 1645, and the Digby-coach intercepts, 1646: still unread
This page: https://dbourdeau.github.io/cyphersolver/further/rupert.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/rupert.html (read it first: how the text was read, the key, the reading)
  Date:       1645–46
  Outcome:    known key applied · partial
  Read now:   8.6% of the deciphered cipher tokens give sense (pieces below may be untouched)
  Files:      https://github.com/dbourdeau/cyphersolver/tree/main/targets/rupert (NOTES.md, key, transcription, reading, scripts)

OPEN GAPS (from NOTES.md, "## Remaining gaps")
  1. [no-key-material: needs a new source] f. 9 (R8623), whole cipher text: - blocker: no-key-material; none of the 73 Add MS 72438 keys nor Lasry's five SP 106 keys fits, and 108 letter groups are too few for a ciphertext-only rebuild.
  2. [no-key-material: needs a new source] f. 10 (R8624), whole cipher text: - blocker: no-key-material; no Add MS 72438 key and none of Lasry's five SP 106 keys fits; 300 letter groups over ~99 homophones, short runs.
  3. [no-key-material: needs a new source] Maurice 7 July 1645: - blocker: no-key-material; key not in Add MS 72438 or on DECODE (Lasry's five SP 106 keys tried 22 Oct); 93 groups.
  4. [no-key-material: needs a new source] f. 104r (R8725), opening line and 21 nomenclator groups (466, 543, 534, 668, 643, 502, 769 ...): - blocker: no-key-material; the letter is in Lasry's SP106-8 (22 Oct 2026), but these groups are absent from R924, his only letter in that key, or unidentified there; deciphered in part, 4 of 15 sentences hold.
  5. [too-short: needs a new source] R8433 Trevor 1645, 54 letter groups: - blocker: too-short; no stable key from cribs/annealing, no print found.
  6. [illegible: needs a new source] f. 107 (R8728), 6 words (header "=≡↑ŧ̥", "≡≡=" after kild, ":≡0" before my heart, the blotted word, "=7L" before for you, the end of "rese.."): - blocker: illegible; blot and writer slips, the gloss skips them, no second copy.

ALREADY TRIED (from NOTES.md, "## Escalation")
  [x] siblings: all 115 DECODE records of Add MS 72438 / 18982 / 18983 listed; all 73 keys of Add MS 72438 screened by range; 6 letter tables applied; f. 106 (R8727) next to f. 107 proved to be its key; R8433 (Trevor, 18982 ff. 51-52) transcribed.
  [x] clear-pages: none with the intercepts f. 9/f. 10 or f. 104; f. 25r index read (keys 80-139 with correspondents); f. 107's interlinear gloss used as crib.
  [x] known-keys: 22 Oct 2026: Lasry's SP 106, SP106-2, -3, -5, -8 keys (sibling targets hm1645, sp106r787, goring1645, rupert1645/sp106r929, sp106r924) on all five numeric texts: SP106-8 deciphers f. 104 in part (Charles I to the Prince of Wales), the rest gibberish. Earlier: keys 118, 123, 125, the Digby-Walsingham key, R8744/R8745, the Parliament key R8741, Tomokiyo's 1644-45 royalist keys (Ormond-Rupert, Nicholas-Rupert May/July 1645): no fit on f. 9, f. 10, f. 104, R8433 or Maurice; f. 106 lower alphabet reads f. 107.
  [x] print: Warburton iii (Maurice; no Trevor letter of the week), cryptiana, web search; 22 Oct: Clarendon State Papers ii and Bruce, Charles I in 1646 grepped for the f. 104 letter (Petrie 1935 lending-only); no decipherment in print for f. 9/f. 10/f. 104/R8433.
  [x] key-rebuild: homophonic annealing on R8433 with and without cribs (chester/bristol) does not converge (54 letter groups over 36 values); f. 9 (108 letter groups) and f. 10 (300) too short for ciphertext-only over ~80-99 homophones; f. 107 homophones added to the f. 106 alphabet.
  [x] retry: f. 104 transcription checked on the full image (no change), key gaps filled from Lasry's R924 interlinear and contexts (f104_key_additions.tsv), reading aligned word by word (0.267, kept as partial). f. 107 re-read with the extended alphabet (95.3%); remaining six words are blots or conjectures. The others need a 1646 royalist key that is not in the volume.

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