t27f: Russian ideas in the factory -- UTF-8 and a 5x7 Latin and Cyrillic font of particles (Closes #10788)

.claude/skills/t27f/SKILL.md

@@ -167,6 +167,7 @@ Traps from this tick (ffmpeg on the lab):
 - lavfi rejects `d=.900`. Print the duration as `$((m/1000)).$(printf %03d $((m%1000)))`.
 - `pkill -f` on the loop script leaves its child renders running. Find them with `ps -eo pid,args | grep '[s]h xf'` and kill them by pid.
 - Through `fs-lab.sh`, `pkill -f 'why_seal'` also matches the ssh command line that carries it and kills your own session; the output comes back empty. Bracket the first letter (`pkill -f '[w]hy_seal'`) so the pattern does not match itself. A killed session leaves the detached ratchets it started running, so several end up writing one log; list them with `ps -eo pid,etimes,args | grep '[c]orpus-only'` before you read a verdict.
+- **A new spec needs its own row in `docs/reports/t27b_expectations.json`**, or `t27b-native-ratchet` fails with UNLISTED. The issue gate still auto-merges the PR red: #10784 landed that way and left five unlisted specs for #10792 to carry. The lab is x86_64, and `t27b test` there ends with "the t27b JIT runs only on arm64". The front end still runs first: `t27b test <spec> --check` prints every blocker before that line. Run a blocked control next to your spec; `specs/t27f/frame_shard.t27` prints `unsupported construct ExprCall(rejected fn)`. If your spec reaches the JIT line with no blocker, and `t27c test-report` passes it, write a pass row. The PR's own arm64 run confirms or refutes the row. Keep the PR a draft until the row is in. Never guess "pass" without that check: a `[N]T` or `ExprCall` blocker turns a guessed row into a regression. Measured on glyph57, idea_factory and petal_menu (#10792).
 
 **Holding the address when the voice runs long (t27#10629).** If an overlay must stay on screen for a minimum time and must also stay off a crossfade, then the crossfade has to move; the overlay cannot. Work out in frames the latest cut that still leaves the last scene its minimum: cut 1 is capped at `BEAT_CUT1_LAST_MS` = 13249. Prove it is the latest with a one-ms-later control. Only the voices the reel speeds up are affected, so the `cmp` diff is limited to those voices and to crossfade 1's offset. The cost is real: the crossfade starts up to 184 ms under the task's last word, and lesson 1's measured voice (1300/4200/6800) is one of the affected voices. Write a test that bounds that overlap.
 
@@ -405,7 +406,7 @@ of particles, and runnable in the OS itself and on FPGA. Two specs do this:
   `BG`, `COL_A/B/C`, `RADIUS`, `GAIN`, `SPRING`, `DAMP`, `LAW`, `FORCE`, `KICK`, `CARD`. The five
   are noir, neon, trit, paper and rain. **Add a preset by adding a column, never a branch in code.**
 - **`specs/t27f/idea_factory.t27` is the factory**, `(IDEA, PRESET) -> RGB24 frames`. It wraps
-  (at most 9 characters per line, 4 lines per scene, `|` cuts a scene), lays out in the 3x5 font,
+  (at most 9 characters per line, 4 lines per scene, `|` cuts a scene), lays out in glyph57's 5x7 font,
   assigns particles to glyph sub-slots and the card border, and closes on `CTA`.
 
 **Keep it FPGA-shaped.** Use Q8 fixed point. The per-step and per-pixel paths use only add,
@@ -442,6 +443,28 @@ particles never settled into letters.
 - **Base the branch on master's tip before the PR.** If the base PR (R3) merged first, reset the branch onto
   `origin/master`. Untracked new specs survive the reset.
 
+### Russian text: UTF-8 and the 5x7 font (t27#10788)
+
+`specs/t27f/glyph57.t27` gives the factory Cyrillic. It decodes UTF-8 (`cp_len`, `cp_at`,
+`cp_count`), folds lower case to capitals, and stores a 5x7 font. The font holds ASCII 32..95
+and only the 21 Cyrillic capitals that have no Latin twin. The 11 look-alikes (A, Ve, Ie, Ka, Em,
+En, O, Er, Es, Te, Ha) and Yo reuse the Latin glyph through the 32-entry `CYR_MAP`.
+
+- **Write non-ASCII text as a `u8` array, never as `"\xNN"`.** L3 keeps sources ASCII. The t27c
+  lexer lowers only `\n`, `\t`, `\\` and `\"`, and keeps `\xD0` as four characters, so a
+  `\xNN` test fails with no error. Use `pub const RU_IDEA : [80]u8 = [208, 167, ...];` and pass
+  `RU_IDEA[0..80]` to a `[]const u8` parameter. `specs/tri/utils/terminal.t27` records the same
+  trap for `\x1b`.
+- **Count widths in characters, keep positions in bytes.** Wrapping compares `cp_count` with
+  `MAXC`. The line start and end stay byte offsets, and the layout loop steps by
+  `bi = bi + cp_len(t, bi)`. An ASCII idea's numbers do not change, so the old tests still pin
+  the old layout.
+- **Guard the font with a duplicate-bitmap test.** Every pair of stored glyphs must differ, and
+  every look-alike must light exactly its Latin twin's pixels.
+- **Render a Russian idea without touching the committed constant.** In the lab copy, `sed`
+  `reel_frames(IDEA)` and `reel_cell(IDEA,` to use `RU_IDEA[0..80]`, next to the `PRESET` and
+  module renames.
+
 ## Check the whole corpus for import cycles (t27#10693)
 
 dependency-cruiser's `no-circular` and madge's `--circular` list every module on a cycle.

.trinity/seals/t27f_glyph57.json

@@ -0,0 +1,33 @@
+{
+  "built_by": "t27c-bootstrap@0.5.2+355d44a39",
+  "closure": [
+    {
+      "spec": "specs/t27f/scene_raster.t27",
+      "spec_hash": "sha256:7be7118d865aa65fd1ccb989ab160df2feb46c9ded0a15ca6510b747301ee4a6"
+    }
+  ],
+  "config": "gen=c,rust,verilog,zig;tests=zig",
+  "gen_hash_c": "sha256:7b616c3b258394696d96adfd9f33a21a788063f0fcc37c591d2982b9e5c44645",
+  "gen_hash_rust": "sha256:cfe5802136fe85e748ec9880d796a0ddb5ee6fe69a4de466dc544f373aa1bfab",
+  "gen_hash_verilog": "sha256:bc6fce86cf24c30a17e3d29e3afebdd28d1aed88c760196a055aec250d2a549e",
+  "gen_hash_zig": "sha256:d57c0bf3b612b865a9df137514ae0e66790196114c7111977ca43d795f67c0e4",
+  "module": "glyph57",
+  "ring": 12,
+  "seal_schema": 2,
+  "sealed_at": "2026-10-19T02:41:07Z",
+  "sealed_by": "t27c-bootstrap@0.5.2",
+  "spec_hash": "sha256:75e98adfcf86a4070c03154e29cf533833c618a1252652f2c20bf91b8425e6cd",
+  "spec_path": "specs/t27f/glyph57.t27",
+  "tests": {
+    "failed": 0,
+    "failing": [],
+    "forced": false,
+    "passed": 7,
+    "total": 7,
+    "vacuous": 0
+  },
+  "toolchain": {
+    "test_runner": "sha256:8512b80da533b79289110fca4a65f3336abd7a059ca4b72ea595d5e33ff8ad10",
+    "zig": "0.16.0"
+  }
+}

.trinity/seals/t27f_idea_factory.json

@@ -1,6 +1,10 @@
 {
   "built_by": "t27c-bootstrap@0.5.2+355d44a39",
   "closure": [
+    {
+      "spec": "specs/t27f/glyph57.t27",
+      "spec_hash": "sha256:75e98adfcf86a4070c03154e29cf533833c618a1252652f2c20bf91b8425e6cd"
+    },
     {
       "spec": "specs/t27f/particle_ds.t27",
       "spec_hash": "sha256:00e84a7492536bf54ac69aa0cd852dea4727477acee12538f9c4b145c3d9c8f3"
@@ -11,23 +15,23 @@
     }
   ],
   "config": "gen=c,rust,verilog,zig;tests=zig",
-  "gen_hash_c": "sha256:49e275c87108c8621d521226b89afb5f6c6a39f74de8e8bba502fbd1e39ad843",
-  "gen_hash_rust": "sha256:7d03e6e99a15344a1c8272b7f96ffc8ddcbfdb1cf44ab7f70f7a0e37847529bc",
-  "gen_hash_verilog": "sha256:0f761cb6e48d10ac555e51b8e5722eb8b02074a87ca2055aaec9241754140c49",
-  "gen_hash_zig": "sha256:0730d911d7047dc707075d16c8ff04afe222f4422a24344eff10b90e72edfdf0",
+  "gen_hash_c": "sha256:6a6ffcf30791e08b93221c1067abfc7e053f13c23dff90de4d9f7c9e23461479",
+  "gen_hash_rust": "sha256:d64150e24319f74e2b9413d45cfbd96a7d8bbc0df9d51c9fac0b68c8837b2efb",
+  "gen_hash_verilog": "sha256:387961ee44ce4ce7f32d4ccb23a4ac58ac6ef688db3b4c8aef38d1c60e41cc18",
+  "gen_hash_zig": "sha256:115d3f8ff262b6fd65b59d760aeb7eff66500b9f77f56577fb22233fefaa65e7",
   "module": "idea_factory",
   "ring": 12,
   "seal_schema": 2,
-  "sealed_at": "2026-10-19T02:25:39Z",
+  "sealed_at": "2026-10-19T02:41:09Z",
   "sealed_by": "t27c-bootstrap@0.5.2",
-  "spec_hash": "sha256:34f59b06d780be9cbbae1b0577e7c96ed5b6b7d2451e61ada1b1dde2fd58b6b8",
+  "spec_hash": "sha256:249909fbd1679b488be14be323c0079735a55895560423934c21daf28c824db9",
   "spec_path": "specs/t27f/idea_factory.t27",
   "tests": {
     "failed": 0,
     "failing": [],
     "forced": false,
-    "passed": 8,
-    "total": 8,
+    "passed": 10,
+    "total": 10,
     "vacuous": 0
   },
   "toolchain": {