Normal mode's s and S search as addr does, through one shared regexp.zig

The sam-style calling convention for mvzr (a line per haystack, . made
[^\\n] only when a pattern names \\n) lived in addr.zig; normal mode's s
and S called mvzr over the raw selection, where ^ meant the selection's
start and . crossed lines. src/regexp.zig now holds the one Regex
(compile, find) both call, and fs.zig and pardes.zig drop an unused mvzr
import. hxdiff and hxparity stay at their known 17 and 6 mismatches, none
of them regex cases.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 5 insertions, 1 deletions

diff --git a/docs/helix-keys.md b/docs/helix-keys.md
index f46f5234..0f847405 100644
--- a/docs/helix-keys.md
+++ b/docs/helix-keys.md
@@ -245,7 +245,11 @@ re-runs the final pattern down the same path, so a submit can never disagree
 with what is on screen. Pressed in a tag, column tag or workspace tag they
 select in that tag's own text, and so does `|` pipe it; `/` searches the
 body wherever it is pressed (`Pane.prompt_for`). Engine: **mvzr** (`build.zig.zon`), a bytecode VM that
-compiles a runtime pattern with no allocator.
+compiles a runtime pattern with no allocator, called the way sam searches
+(`src/regexp.zig`, shared with a pane's `addr` file): each line is its own
+haystack, so `^` and `$` match at every line's start and end and `.` never
+crosses a newline, and a pattern naming `\n` runs over the whole selection.
+Where helix's `^` is only the selection's start, this is sam's.
 
 | Key | Behavior | Notes | Status |
 | --- | --- | --- | --- |