clipboard, n/N and the tty prompt: three things that were half-wired

Three changes that all turned out to be the same shape -- a feature that
worked in one direction, or for one pane kind, and quietly did not in the
others.

CLIPBOARD. Every register write emitted set_clipboard, so deleting one
character threw away whatever the desktop was holding; multi-cursor yank took
the join's early return and emitted nothing at all, so the same key reached
the clipboard on one cursor and not on two. Nothing could READ the clipboard:
the SDL shell had no SDL_GetClipboardText anywhere in it, and the tty shell
never asked for OSC 52, so `p` from another application was dead in both.

Now it is helix's split. y/d/c/p/P/R and the acme chords are the DEFAULT
REGISTER and nothing else; the system clipboard is five words on helix's own
letters -- SPC y, SPC Y, SPC p, SPC P, SPC R -- spelled as builtins so they
land in Help and are executable like every other verb. The one exception is
the tag `y` chord, which still mirrors out because a tag is always insert, so
SPC cannot be pressed there, and copying the path out is the whole point of
the chord.

Reading is a new read_clipboard effect answered by an ordinary Event.paste, so
the round trip is honest about being one: SDL and NSPasteboard answer inside
the same drain, the browser answers a promise, and a terminal answers over
OSC 52 or -- far more often -- refuses. A refused read is a paste that does
not happen, and the request dies at the next keystroke rather than landing
minutes late in whatever pane is focused by then.

The tty shell also enables BRACKETED PASTE now and coalesces
paste_start..paste_end into one event. Before this a paste arrived as a flood
of individual key presses: plausible in insert mode, and in normal mode every
pasted character ran as a command.

n/N. They stepped the armed results buffer and immediately Looked each row, so
you could not walk past a hit without opening it. They are a MOTION now:
select the next look-able text, open nothing, and let Enter decide. What they
step is the largest whitespace-delimited run look.resolve can act on
(look.lookableSpan, wrapper punctuation peeled), over a RING of panes -- every
pane that has performed a look, most recent first, then the output buffers
that have not, newest first, and only if both are empty the pane in front of
you. N is the exact inverse of n, computed rather than remembered: both
directions ask the same question about the same spans and compare against the
column the walk parks on, so x presses one way and x back land exactly where
you started, pane boundaries and the ring's seam included.

A ring rather than a list with two ends because a shell's cursor sits at the
prompt, below everything it has printed, so a walk that could not come round
would have nowhere to go on the very first press -- which is the case n/N were
written for.

One motion everywhere, no pane-kind or buffer-kind special case. The only
thing a buffer may change is the GRAIN of what a step selects, and it does it
with one flag rather than a branch: output_pane.Traits.commands (renamed from
`executes`, which named one reader's behaviour rather than the fact) makes a
row select WHOLE, because a ThemeSel line is a word to run and has no path
inside it to pick out. `]d`/`[d` are not n/N -- they are helix's diagnostic
motions, their job is to ARRIVE, and they still reach searchStep.

THE TTY PROMPT. Leaving raw tty blanked the prompt row, and the command you
had typed at that prompt shares the row, so it went too -- a shell out of tty
read as output only. OSC 133 marks the row CELL by cell, so the two are
separable: config.tty_blank = .prompt cuts the prompt's own columns and leaves
the command, left-hugged at column 0 in line with the output under it rather
than in a bay of blanks. .prompt_and_input is the old behaviour, kept.

Because the row is now something you can put a cursor in, enterTty adds the
hidden prompt width back before asking ghostty to walk the shell's own cursor
to it -- the modal column on a cut row is short by exactly that much.

Verified: unit-test 186/186 (nine new), snap 87/87 (new ttyprompt.snap),
hxdiff 481 and hxparity 561 with 0 mismatches, tty and gui both build. And
against the real binaries rather than the harness: in a pty, SPC y emits OSC
52 carrying exactly the selection while plain y emits nothing, SPC p issues
the read and pastes the reply, and a bracketed paste of "dd..." inserts text
instead of deleting two lines. In a real SDL window, SPC y then SPC p round
trips through the system clipboard while the default register holds different
text. Setting tty_blank back to .prompt_and_input reproduces all 86 old
goldens byte for byte.

1 files changed, 40 insertions, 2 deletions

diff --git a/src/config.zig b/src/config.zig
index 189d6a0e..d6d6813d 100644
--- a/src/config.zig
+++ b/src/config.zig
@@ -109,6 +109,20 @@ pub const leader_path = paths: {
         .Lspwhy = "lw",
         .Del = "d",
         .Kill = "k",
+        // THE CLIPBOARD MENU, on helix's own five letters and nowhere else.
+        // These are the only paths in the table that keep their helix spelling
+        // unprefixed, and they can: `y` `Y` `p` `P` `R` were free at the top
+        // level, and moving them into a group would have made the one thing
+        // here that IS helix's leader stop looking like it.
+        //
+        // Bare `y`/`p`/`P`/`R` remain the DEFAULT register — that split is the
+        // whole design (see builtins.zig's clipboard section), and it is why
+        // an ordinary delete no longer reaches past the editor.
+        .ClipYank = "y",
+        .ClipYankMain = "Y",
+        .ClipPaste = "p",
+        .ClipPasteBefore = "P",
+        .ClipReplace = "R",
         // the `f` file group (spacemacs): Save left vim's `w` to join Find and
         // New here, which frees `w` for the window group (SPC w h/j/k/l).
         .Save = "fs",
@@ -282,6 +296,27 @@ pub const tty_toggle_default: u21 = 'b';
 /// means what Escape always means.
 pub const tty_toggle_alt: []const Chord = &.{.{ .cp = Key.escape, .shift = true }};
 
+/// What LEAVING raw tty mode hides on the shell's prompt rows.
+///
+/// A prompt is CHROME. `user@host ~/src $` is redrawn on every keystroke, says
+/// nothing a second time, and is never what you want to select, look at or
+/// edit — so blanking it is most of what turns a scrollback into a readable
+/// document, and pardes has always done it (OSC 133 is how it knows).
+///
+/// What it USED to take with it was the command you had typed at that prompt,
+/// because the two share a grid row and the row was the unit. That command is
+/// content: the one thing on the row worth keeping, and the thing you reach
+/// for `b` to get at in the first place. OSC 133 marks the two separately —
+/// per CELL, not just per row — so `.prompt` blanks the prompt's own cells and
+/// leaves the input sitting in the COLUMNS it really occupies. Those columns
+/// are not cosmetic: clicking the command in normal mode and pressing the
+/// toggle carries the click into the shell's own cursor (promptClickMove),
+/// which counts them.
+///
+/// `.prompt_and_input` is the older behaviour, kept for anyone who wants a
+/// terminal to read as output and nothing else.
+pub const tty_blank: enum { prompt, prompt_and_input } = .prompt;
+
 // ---- the tag line and the topbar ----
 
 // The topbar is a HAND-PICKED subset in a fixed order, not a derivation: row 0
@@ -801,14 +836,17 @@ pub const select_regex: []const Chord = &.{.{ .cp = 's' }};
 pub const split_regex: []const Chord = &.{.{ .cp = 'S' }};
 
 // ---- edits ----
+//
+// Every one of these reads or writes the DEFAULT register and only that.
+// The system clipboard is five separate words on `SPC y Y p P R`, which is
+// helix's split and the reason `d` cannot silently eat what you copied out of
+// a browser. See leader_path above and builtins.zig's clipboard section.
 
 pub const delete: []const Chord = &.{.{ .cp = 'd' }};
 pub const delete_noyank: []const Chord = &.{.{ .cp = 'd', .alt = true }};
 pub const change: []const Chord = &.{.{ .cp = 'c' }};
 pub const yank: []const Chord = &.{.{ .cp = 'y' }};
 pub const replace_with_yank: []const Chord = &.{.{ .cp = 'R' }};
-/// helix: the DEFAULT register, not the system clipboard — most terminals
-/// refuse the OSC 52 read, so a round trip would never come back
 pub const paste_after: []const Chord = &.{.{ .cp = 'p' }};
 pub const paste_before: []const Chord = &.{.{ .cp = 'P' }};
 pub const switch_case: []const Chord = &.{.{ .cp = '~' }};