Look and Exec are builtins like any other

Their only special feature is now the keys they are assigned. `Look main.zig`
typed in a tag is the same look a right click is; config.look_cmd/exec_cmd
point the two buttons and Enter/Tab at them, so retargeting Enter to Grep is
one line. actOnSelection — a hand-written cascade with the builtin dispatch
nested inside it — is gone, and the `button` parameter it threaded through five
KEYBOARD call sites went with it.

New syntax, spelled once in config.zig: @`ls -la` names a command to run
rather than a file to open. Word expansion takes the quoted run whole, the way
acme does for its own </|/> words, so a click inside one does not hand Look the
fragment `ls`.

And it nests: @`Look .` unwraps, re-enters the dispatcher, and looks at the
directory. Guarded at depth 8, which is unreachable today (every re-entry
strips a word or a delimiter pair, so the string strictly shrinks) and exists
for a future syntax that does not shrink.

leader_path is now optional: a builtin may have no SPC path when its shortcut
is a key and a mouse button. New golden cmdword; the other 59 unmoved.

1 files changed, 32 insertions, 2 deletions

diff --git a/src/builtins.zig b/src/builtins.zig
index 500ce264..cf144d33 100644
--- a/src/builtins.zig
+++ b/src/builtins.zig
@@ -106,6 +106,36 @@ pub fn Builtin() type {
     return @Enum(Tag, .exhaustive, &names, &std.simd.iota(Tag, cmds.len));
 }
 
+// ---- the two acme verbs ----
+
+// Look and Execute are the verbs the whole environment is built on, and they
+// are BUILTINS: `Look main.zig` typed in a tag and executed is the same look a
+// right click on `main.zig` is, `Exec ls` the same as a middle click on `ls`.
+// The mouse buttons and Enter/Tab are not a second path into them any more —
+// they are two bindings pointing here (config.look_cmd / exec_cmd), the status
+// `SPC f s` has relative to Save. That is the whole feature: what used to be a
+// `button` parameter threaded through every keyboard call site, with the
+// builtin dispatch nested INSIDE it, is now one word each.
+//
+// The operand is `arg` in both — a name's tail (`Look main.zig`), else the
+// selection a chord kept, else the word the gesture pointed at, which the
+// gesture resolves and passes. Nothing to act on means nothing happens, the
+// way `Save` on a terminal is inert.
+
+pub const Look = struct {
+    pub fn run(c: Ctx) void {
+        c.p.lookAt(c.id, c.arg orelse return);
+    }
+};
+
+pub const Exec = struct {
+    pub fn run(c: Ctx) void {
+        // the destination pane is Look's business (it focuses what answered);
+        // an execute deliberately leaves you where you were
+        _ = c.p.execute(c.id, c.arg orelse return);
+    }
+};
+
 // ---- session ----
 
 pub const Kill = struct {
@@ -159,8 +189,8 @@ pub const Crt = struct {
 };
 
 // The image pane's three renderer toggles. They used to be words the image tag
-// printed and actOnSelection matched by hand; as builtins they are executable
-// anywhere, pressable under SPC and listed by `SPC ?`, which is the whole
+// printed and the execute dispatcher matched by hand; as builtins they are
+// executable anywhere, pressable under SPC and listed by `SPC ?`, the whole
 // reason the tag no longer carries them. Each acts on the pane it runs in and
 // is inert anywhere else, the way Save is on a terminal — flipping the field is
 // the whole toggle: drawImage re-matches the glyph grid when it sees