FABRIC.md: item 4.4m -- REPL text size and strip height decided

Design decision, no code change (4.4j's constants are already the
final values). Text size 20px (unchanged from 4.4j), 4 visible lines,
strip height 96px (4 x the existing 24px cell height, no extra
padding -- leading is already baked into that cell height).

Flagged the constraint this feeds into before deciding: 4.4o needs a
640x480 scroll-box to fit inside CANVAS on the 600px-tall
aarch64/riscv64 screens, which only leaves 24px of slack over the
480px minimum once the 96px strip is subtracted. 4.4n's gap choice
must stay <=24px on those architectures or 4.4o's fit check fails --
recorded now so it's not a surprise two items later.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

FABRIC.md

@@ -5456,7 +5456,7 @@ document and committing that amendment as its own item.*
   > (CANVAS geometry) computed per-architecture needs to actually branch on this, not assume a
   > single shared screen size.
 
-- [ ] **4.4m — Decide REPL-strip pixel height.** Currently undefined anywhere in this document
+- [x] **4.4m — Decide REPL-strip pixel height.** Currently undefined anywhere in this document
   or the code. Once 4.4j lands, REPL text renders via `TTF-TEXT` at some chosen point/pixel
   size (also not yet chosen) — strip height derives from that size's line height plus padding,
   not from `font_8x16.c`'s fixed 8×16 cell.
@@ -5464,6 +5464,31 @@ document and committing that amendment as its own item.*
   recorded here.
   *Refs:* §27.8.
 
+  > **Decided with Captain Bob, 2026-08-11.** Before deciding, flagged the real constraint this
+  > choice feeds into: 4.4o needs a 640×480 scroll-box to fit inside CANVAS, and CANVAS height
+  > = screen height (4.4l) − strip height − a fixed gap (4.4n). On aarch64/riscv64 (600px tall),
+  > that leaves very little room — strip height + gap must stay well under 120px or 4.4o's own
+  > text says it must stop and report rather than silently shrink the box.
+  >
+  > **Text size: 20px, unchanged from 4.4j's provisional value** — no rework, and 4.4j's own
+  > `VT100_TTF_SIZE_PX`/`VT100_TTF_CELL_W_PX`/`VT100_TTF_CELL_H_PX` constants are now the
+  > final values, not placeholders (their code comments calling them "provisional, pending
+  > 4.4m" are stale as of this decision — worth a follow-up comment cleanup when 4.4n/4.4o
+  > touch that code next, not urgent enough to justify a code-only commit for comment text
+  > alone).
+  >
+  > **Visible lines: 4.** **Strip height: 4 × `VT100_TTF_CELL_H_PX` (24px) = 96px** — no
+  > additional padding layered on top of that, since each line already carries 4px of leading
+  > baked into the 24px cell height itself (`VT100_TTF_CELL_H_PX`'s own comment: "size + 4px
+  > leading/descender").
+  >
+  > **Checked against the 480px constraint, not assumed safe:** on the 600px-tall
+  > aarch64/riscv64 screens, `600 − 96 = 504px` remains for CANVAS + gap. That's only 24px of
+  > slack over the 480px minimum — a generous gap choice in 4.4n (e.g. anything over ~24px)
+  > would fail 4.4o's fit check. **4.4n's gap must stay ≤ 24px on the small architectures**,
+  > flagged here explicitly so it isn't discovered as a surprise failure two items later. amd64
+  > (800px tall) has no such pressure (`800 − 96 = 704px` for CANVAS + gap).
+
 - [ ] **4.4n — CANVAS rectangle definition, per architecture.** Screen height (4.4l) minus REPL
   strip height (4.4m) minus the small fixed gap (exact pixel value chosen here) between CANVAS
   and the strip.