shaders: -Dprebuilt-shaders, so a gui build needs no Vulkan SDK

glslc is the one build input that wants a tool a stock machine does not have,
and it is also the input that changes least often: eight GLSL files that have
outlived several rewrites of everything around them. Asking every machine that
wants to run the SDL shell for shaderc is the wrong trade.

The SPIR-V is now COMMITTED, under shaders/prebuilt/, and -Dprebuilt-shaders
embeds that copy instead of shelling out. The default stays the honest one --
compile the shaders that are actually in the tree -- because the flag trades a
dependency for a freshness problem: with it on, the .glsl sources are not build
inputs at all, so editing one changes nothing.

`zig build shaders` is the other half, and it is deliberately independent of
-Dplatform: it recompiles every shader and writes the result back into the
tracked directory, so whoever changes a shader refreshes the cache on a machine
that has the compiler and commits the diff. `jj diff shaders/prebuilt` after it
is the freshness check -- empty means the cache was already current.

The shader list is also spelled once now (gui_shaders): the eight embeds, the
eight glslc runs and the refresh step all read it, so adding a shader is a name
there plus the @embedFile in gui.zig, not three edits in two places.

Verified: -Dplatform=gui -Dprebuilt-shaders builds with glslc absent from PATH,
and image-harness passes on that binary -- real SDL GPU pipelines built from the
committed SPIR-V, 512 source pixels read back. The default gui build still runs
the eight glslc steps; tty runs none. The committed bytes are identical to a
fresh glslc run, and `zig build shaders` is idempotent.

2 files changed, 7 insertions, 3 deletions

diff --git a/docs/design.typ b/docs/design.typ
index ff013f49..bd8b767c 100644
--- a/docs/design.typ
+++ b/docs/design.typ
@@ -253,8 +253,12 @@ zig-tree-sitter + 26 grammars — all pinned
 through `zig fetch` and wired in `build.zig`. Generated during the build:
 `highlights.scm` → an options module; the vendored helix/zed theme
 sources → the generated half of the theme ring; the tracked `.zig` sources →
-the web shell's read-only archive; eight GLSL shaders → SPIR-V. The tutor and
-the embedded font are plain `@embedFile`s, not codegen. Debug builds are
+the web shell's read-only archive; eight GLSL shaders → SPIR-V. That last one is
+the only build input wanting a tool a stock machine lacks (`glslc`), so it is
+also the only one whose output is committed: `zig build shaders` writes
+`shaders/prebuilt/*.spv` and `-Dprebuilt-shaders` embeds that copy rather than
+shelling out, which is what lets a gui build need nothing but a C toolchain. The
+tutor and the embedded font are plain `@embedFile`s, not codegen. Debug builds are
 incremental for the seconds-loop; release builds are the product.
 
 = What is deliberately absent
diff --git a/docs/helix-keys.md b/docs/helix-keys.md
index eafe9a9c..611e7761 100644
--- a/docs/helix-keys.md
+++ b/docs/helix-keys.md
@@ -98,7 +98,7 @@ language-backend queries, and the shell pipe.
 | `Space` (normal, body) | the pardes LEADER: a key path from here runs a BUILTIN with no arguments — the same builtins the topbar and the tags hold. `SPC k` Kill, `SPC d` Del, `SPC f s` Save, `SPC f n` New (an empty temporary file focused in the calling pane's column), `SPC f f` Find (fd over the pane's directory, results into `+Search`), `SPC f g` Grep (grep -R over the CONTENTS of every pane's directory, the ones another pane already covers dropped, rows relative to the asking pane's own directory, results into `+Search`; like Find it takes an ARGUMENT — `Grep foo` executed, or a selection chorded onto the word, searches that and skips the input), `SPC h t` Tutor, `SPC c n`/`SPC c d` Newcol/Delcol, `SPC y/Y/p/P/R` the five clipboard words (next row), `SPC t d/c/n/r` Debug/Colors/NextColor/Crt, `SPC t t` ThemeSel (the whole theme ring as `Theme <name>` rows in an output buffer — rows that are COMMANDS rather than places, so a theme is previewed by EXECUTING one, Tab or a middle click; `n`/`N` do not run them, they step past to the next look-able text on the ring), `SPC t p/l/a` Petscii/Palette/Ascii (an image pane's renderer toggles — the words its tag used to spell out, so the bar stays a bar), `SPC s d`/`SPC s r` Dump/Restore, `SPC w h/j/k/l` Left/Down/Up/Right (directional pane focus — the `Ctrl-w` prefix's four moves as builtins), `SPC j o`/`SPC j i`/`SPC j j`/`SPC j l` Back/Forward/Last/Jumplist (the jump stack: walk it back, walk it forward, hop to the pane before this one — what body-normal Esc runs — and read the stack as a clickable buffer). `?` at ANY depth opens the Help builtin listing what the prefix can still reach (`SPC ?` = all, `SPC h ?` = the docs group), into a `+Help` output buffer. The pending path shows at the right edge of the active pane's tag; Esc — or any unmapped key — abandons it | helix spends Space on pickers/LSP (section C); pardes has neither, and acme's builtins are what a leader is for. Enum-derived: the paths, the Help lines and the execute dispatch all fold out of one `Builtin` enum at comptime. Normal mode on a BODY only — tags are always insert, tty keys belong to the program | pardes-specific |
 | `SPC y` `SPC Y` `SPC p` `SPC P` `SPC R` | helix's clipboard menu on helix's own letters: yank the selection to the system clipboard (`ClipYank`) or the PRIMARY selection alone (`ClipYankMain`), paste the system clipboard after (`ClipPaste`) / before (`ClipPasteBefore`) the selection, replace the selection with it (`ClipReplace`) | the ONLY five words in pardes that touch the desktop's clipboard — `y`/`d`/`c`/`p`/`P`/`R` and the acme cut/paste chords are the internal register alone. Builtins rather than bare chords because a leader path names a builtin: they land in Help's index and are executable words like every other verb. One divergence: pardes keeps a single register VALUE where helix keeps one per range, so `SPC y` at N cursors joins them with newlines (`Pardes.setYank`, the divergence `msel-yank-paste` already waives). On a tty the write is OSC 52 out and the READ is OSC 52 back, which many terminals refuse or gate — so `SPC y` works there and `SPC p` can be a no-op | out of corpus |
 | a paste from the OUTER terminal | one `Event.paste`, spliced in at the cursor | the tty shell enables bracketed paste and coalesces `paste_start`..`paste_end` into a single event; before that the bytes arrived as individual key presses and normal mode RAN them, which is how a pasted `d` deleted a line. The bytes deliberately never enter the yank register — clipboard and default register are separate stores in both directions | pardes-specific |
-| `/` (any pane) | pardes' own plain-substring search into a `+Search` output buffer: the tag takes the pattern, Enter fills the buffer, and its rows are ordinary look targets | KEEP, do not touch; not in the corpus (helix `/` is regex search). The stepping half is the next row | pardes-specific |
+| `/` (any pane) | pardes' own plain-substring search into a `+Search` output buffer: the tag takes the pattern, Enter fills the buffer, and its rows are ordinary look targets. Enter also GOES to the first row — the buffer is focused and then the step `n` is and the look Enter is run in it (`Pardes.lookFirstHit`), so `/foo` lands on the first hit with the matched span selected. A pattern that matched nothing opens its empty buffer and moves nothing | KEEP, do not touch; not in the corpus (helix `/` is regex search). Find and Grep answer with OTHER files and deliberately do NOT jump. The stepping half is the next row | pardes-specific |
 | `n` / `N` (any pane) | MOTION, not a jump: move the SELECTION to the next / previous look-able text and open NOTHING. Enter — the look chord — on what it leaves selected is what opens it | KEEP, do not touch; not in the corpus (helix's `n`/`N` walk regex search hits). The text stepped is the largest whitespace-delimited run `look.resolve` can act on (`look.lookableSpan`, wrapper punctuation peeled off both ends), and the walk is a RING across PANES: every pane that has performed a Look, most recent first (`Pardes.look_src`), then the output buffers that have not, newest first, and only when both are empty the active pane. Exhausting a pane enters the next at its first (forward) / last (backward) span and the end wraps to the start, so `N` is the exact inverse of `n`. What it lands on becomes an EXPLICIT `vsel` with the cursor on its FIRST column, in the pane the walk focuses. ONE motion in every pane kind and every buffer kind — a PDF steps the `+Search` buffer its own search filled, `n` to select the row and Enter to jump. The single thing a buffer may change is the GRAIN of what a step selects, and it changes it with one flag rather than a branch: `output_pane.Traits.commands` makes a step take the WHOLE LINE, because a command list (`ThemeSel`/`FontSel`) holds words to run and there is no path inside `Theme gruvbox` to pick out. Tab on what `n` selected wears the theme, which is the same middle click on the row is. `]d`/`[d` are helix's diagnostic motions, a different binding, and they do still jump to each diagnostic (`docs/lsp.md`) | pardes-specific |
 | insert: printable text | file: real edit; terminal: typed run splice | | helix-verified (file) |
 | insert: `Enter` | newline; keeps the current full indent levels and adds one 4-space logical tab when the text before the cursor ends in `(`, `[`, `{`, or `)` (including `})`) | plain lines match `insert_newline`; delimiter heuristic is pardes-specific | helix-verified (plain) / pardes-specific (delimiter) |