FABRIC.md: split 4.3.1 into 4.3.1-4.3.4, one task per checkbox

The prior commit bundled four separate tasks (test pattern, screenshot
capability, coordinate machinery, cube checkpoint) into a single numbered
list inside one checkbox, violating the punch list's own convention of one
task per box. Split into four checkboxes and updated §27 to match.

FABRIC.md

@@ -3646,27 +3646,30 @@ document and committing that amendment as its own item.*
   >
   > **Discussion held 2026-08-07.** `.claude/CONSOLE.md` is a rough prior working draft,
   > superseded — not edited further, not treated as authoritative. Console's design lives
-  > in this document from here on. First slice scoped below as 4.3.1.
+  > in this document from here on. First slice broken out below as 4.3.1–4.3.4. Explicitly
+  > out of scope for all four: raster image (PNG/JPEG) rendering as fabric backgrounds —
+  > real direction, raised 2026-08-07, deliberately deferred past this slice; also fonts,
+  > scrolling, cursor/VT100 semantics, the Hermes message protocol, and Console as a fleet
+  > VM under Hera's birth protocol — later 4.3.x items, scoped once this slice is reviewed.
 
-- [ ] **4.3.1 — Framebuffer sanity and the coordinate fabric.** First real work on Console:
-  prove the raw hardware boundary before anything Stadium- or VM-shaped touches it. *Refs:*
-  §27. Scope:
-  1. Confirm `framebuffer.c` is wired to the real UEFI GOP `BootInfo` and draw a simple
-     orientation-revealing test pattern (raw pixel primitives only — no coordinate/Z
-     machinery yet).
-  2. Add QEMU monitor/QMP screenshot capability (`screendump`) so the result can actually
-     be inspected — none exists today; all three `qemu` targets currently run with
-     `-display none` and no monitor attached.
-  3. Stand up Cartesian coordinate machinery: origin bottom-left `(0,0)`, Y-up, plus a new
-     Z axis — depth-into-screen, not height. Fixed orthographic projection for now (angle
-     TBD — true 45° cavalier vs. 2:1 isometric, still open); explicitly a placeholder, not
-     the final projection — this is heading toward real 3D animation later, not a static
-     scene.
-  4. Draw a cube using the new machinery. Stop here for review — first real exercise of the
-     coordinate/projection math, not expected to be fast.
+- [ ] **4.3.1 — Framebuffer sanity: draw a test pattern.** Confirm `framebuffer.c` is wired
+  to the real UEFI GOP `BootInfo` and draw a simple orientation-revealing test pattern, using
+  the existing raw pixel primitives only — no coordinate/Z machinery yet. *Refs:* §27.1.
 
-  **Explicitly out of scope for 4.3.1:** raster image (PNG/JPEG) rendering as fabric
-  backgrounds — real direction, deliberately deferred past this slice.
+- [ ] **4.3.2 — QEMU screenshot capability.** Add a monitor/QMP socket to the `qemu` targets
+  (mirroring the existing serial-socket pattern) so `screendump` can be issued and the 4.3.1
+  test pattern actually inspected. None exists today — all three targets currently run with
+  `-display none` and no monitor attached. *Refs:* §27.2.
+
+- [ ] **4.3.3 — Cartesian coordinate machinery.** Origin bottom-left `(0, 0)`, Y-up, plus a
+  new Z axis (depth-into-screen, not height) and a fixed orthographic projection as a
+  placeholder — not the final projection, no perspective/camera work yet. Angle open: true
+  45° cavalier vs. 2:1 pixel-art isometric; settle when this item is actually implemented.
+  *Refs:* §27.3.
+
+- [ ] **4.3.4 — Checkpoint: draw a cube.** First real exercise of the 4.3.3 coordinate/
+  projection machinery. Stop and review here before scoping the next 4.3.x item — not
+  expected to be fast. *Refs:* §27.4.
 
 - [ ] **4.4 — Artemis last.** It works today; it is the thing that cannot be broken.
   *Refs:* §10.
@@ -3978,29 +3981,29 @@ sites).
 **STATUS: design-stage, 2026-08-07.** Supersedes `.claude/CONSOLE.md` as the authoritative
 Console design document. `CONSOLE.md` was a rough prior working draft and is not edited
 further; nothing in it should be treated as decided just because it is written down there.
-This section covers 4.3.1 only — the groundwork slice: verify the hardware boundary works
-and stand up the coordinate machinery. It is explicitly *not* the full Console specification
-(fonts, scrolling-as-a-VM-behavior, message protocol from Hermes, etc.) — those are later
-items under 4.3, scoped once 4.3.1's checkpoint is reviewed.
+This section covers 4.3.1–4.3.4 only — the groundwork slice: verify the hardware boundary
+works and stand up the coordinate machinery. It is explicitly *not* the full Console
+specification (fonts, scrolling-as-a-VM-behavior, message protocol from Hermes, etc.) —
+those are later items under 4.3, scoped once this slice's checkpoint (4.3.4) is reviewed.
 
-### 27.1 The hardware boundary already exists
+### 27.1 The hardware boundary already exists (4.3.1)
 
 `console_fb_init()` (`hal/console.c:269`) calls `fb_init()` with real UEFI GOP data from
 `boot_info->framebuffer`, but only after POST completes, immediately before the REPL starts
 (`kernel_main.c:800-807`). `include/starkernel/framebuffer.h` already exposes raw pixel
 primitives: `fb_put_pixel`, `fb_fill_rect`, `fb_draw_glyph` (8×16 cells), `fb_scroll_rows`.
-There is nothing to build to get pixels on screen — 4.3.1's first task is *verification*,
-not construction: draw a simple, orientation-revealing test pattern with the existing
-primitives and confirm it displays right-side up.
+There is nothing to build to get pixels on screen — 4.3.1's task is *verification*, not
+construction: draw a simple, orientation-revealing test pattern with the existing primitives
+and confirm it displays right-side up.
 
-### 27.2 No screenshot capability exists today
+### 27.2 No screenshot capability exists today (4.3.2)
 
 All three `qemu` targets in `Makefile.starkernel` run with `-display none` and attach only a
 serial chardev socket (for the log) — no monitor, no QMP socket. There is no way today to
-issue QEMU's `screendump` command. 4.3.1 adds a monitor/QMP socket (mirroring the existing
+issue QEMU's `screendump` command. 4.3.2 adds a monitor/QMP socket (mirroring the existing
 serial-socket pattern) so the framebuffer can actually be inspected as a `.ppm` after a run.
 
-### 27.3 Coordinate system
+### 27.3 Coordinate system (4.3.3)
 
 - **Origin bottom-left**, `(0, 0)`. Traditional Cartesian, not raster/top-left-Y-down. The
   framebuffer's native memory layout is top-left origin, Y-down — the Y-flip transform must
@@ -4015,15 +4018,10 @@ serial-socket pattern) so the framebuffer can actually be inspected as a `.ppm`
   cleanly on a pixel grid). Not settled; settle it when the projection math is actually
   written, not speculatively here.
 
-### 27.4 Checkpoint: a cube
+### 27.4 Checkpoint: a cube (4.3.4)
 
-4.3.1's acceptance is a cube rendered on screen using the coordinate/projection machinery
-above — the first real exercise of that math, expected to take real effort, not a quick
-add. Stop and review here before scoping the next 4.3.x item.
-
-### 27.5 Explicitly out of scope for 4.3.1
-
-- **Raster image rendering** (PNG/JPEG decode, composited onto the fabric as backgrounds).
-  Real direction, raised 2026-08-07, deliberately deferred past this slice.
-- Fonts, scrolling, cursor/VT100 semantics, the Hermes message protocol, Console as a fleet
-  VM under Hera's birth protocol — all later 4.3.x work, not 4.3.1.
+Acceptance for this whole slice is a cube rendered on screen using the 4.3.3 coordinate/
+projection machinery — the first real exercise of that math, expected to take real effort,
+not a quick add. Stop and review here before scoping the next 4.3.x item. Out-of-scope list
+for 4.3.1–4.3.4 is recorded once, at the 4.3 punch-list entry itself (§25.5), not repeated
+per sub-item.