the gui shell watches files too

It never did — the effect arm was `.watch => {}` with a comment saying a shell
that never delivers the event simply never reloads. That was written as a
deliberate scope cut and it is the whole bug: the user runs pardes-gui.

The tty watcher was fine, and I proved all four suspicions false against a real
binary in a real pty with the write done by a stranger process and NO input
delivered afterwards: the loop does wake (postEvent signals an empty queue),
zig fmt's rename-over does fire MOVED_TO and is caught, three panes across two
directories all reload and closing one leaves its neighbour still following,
and the self-write hash guard does not swallow a real change. The live session
even had its inotify mark on src with the right mask and re-read config.zig
when I touched that directory.

Duplicated rather than shared with tty.zig, the way the two shells already each
own LspJob, forkShell and their pty readers. The headless PARDES_TEST_GRID path
deliberately passes -1: its contract is one frame per scripted input, and a
reload on its own clock would put an unasked-for frame in the stream.

filewatch.snap proved less than it looked. Its real blind spots were the
rename-over shape — the old script only truncated, so it saw CLOSE_WRITE and
never MOVED_TO — multiple directories, and the one that mattered: the suite
only ever runs the TTY binary, so it structurally cannot see a gui-only
regression. It now uses a new `run` directive whose writer is a child of the
RUNNER, so nothing it does reaches an app pty.

3 files changed, 93 insertions, 33 deletions

diff --git a/test/snapshot.zig b/test/snapshot.zig
index 4344654c..19b65a02 100644
--- a/test/snapshot.zig
+++ b/test/snapshot.zig
@@ -28,6 +28,7 @@
 //   file <name> <content>     create file in the script's cwd (before start)
 //   lines <name> <n> [tail]   create file with n numbered lines, tail on each
 //   dirmk <name>              create a subdirectory
+//   run <shell...>            run a command in the script's cwd (NOT in a pane)
 //   start <rows> <cols> [arg] fork the app in a pty (optional extra CLI arg)
 //   wait <ms> <needle...>     pump until needle appears on the grid (fails hard)
 //   settle <ms>               pump for a fixed duration
@@ -62,6 +63,7 @@ pub const std_options: std.Options = .{ .log_level = .err };
 
 extern "c" fn setenv(name: [*:0]const u8, value: [*:0]const u8, overwrite: c_int) c_int;
 extern "c" fn execvp(file: [*:0]const u8, argv: [*:null]const ?[*:0]const u8) c_int;
+extern "c" fn system(cmd: [*:0]const u8) c_int;
 
 const SNAP_BASE = "/tmp/pardes-snap";
 var trace_stable = false;
@@ -379,6 +381,14 @@ fn runScript(arena: std.mem.Allocator, exe_z: [:0]const u8, script_path: []const
             try eh.writeFile(try arena.dupeZ(u8, name), ppm.items);
         } else if (std.mem.eql(u8, cmd, "dirmk")) {
             try mkdir(arena, tok.next() orelse return error.BadScript, false);
+        } else if (std.mem.eql(u8, cmd, "run")) {
+            // A writer that is NOT a pardes pane. `file` mid-script is already
+            // one, but it cannot express the rename-over that is how a
+            // formatter actually replaces a file — and the difference is a
+            // different inotify event. This runs in the script's cwd, as a
+            // child of the RUNNER, so nothing it does reaches the app's ptys:
+            // whatever the app then shows, it woke up for by itself.
+            if (system(try arena.dupeZ(u8, tok.rest())) != 0) return error.RunFailed;
         } else if (std.mem.eql(u8, cmd, "start")) {
             const rows = try std.fmt.parseInt(u16, tok.next() orelse return error.BadScript, 10);
             const cols = try std.fmt.parseInt(u16, tok.next() orelse return error.BadScript, 10);
diff --git a/test/snapshots/filewatch.golden b/test/snapshots/filewatch.golden
index 64c43c85..71a56bba 100644
--- a/test/snapshots/filewatch.golden
+++ b/test/snapshots/filewatch.golden
@@ -2,8 +2,8 @@
 |Kill Newcol Tutor Debug NextColor Dump Find Grep Help
 |  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  NOR /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
 |     1 liMYEDITne 1
-|     2 line 2                                       w.txt                                             w.txt
-|     3 line 3
+|     2 line 2                                       sub  w.txt                                        sub  w.txt
+|     3 /tmp/pardes-snap/filewatch/cwd/sub/s.txt
 |     4 line 4
 |     5 line 5
 |     6 line 6                                         w.txt
@@ -15,12 +15,29 @@
 |    12 line 12
 |    13
 |
-|                                                    NOR /tmp/pardes-snap/filewatch/cwd Del
+|  NOR /tmp/pardes-snap/filewatch/cwd/sub/s.txt Sav  NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 line 1
+|     2 line 2                                       sub  w.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9
 |
-|                                                    w.txt
 |
 |
 |
+== snap reloaded grid=150x30 cursor=15,2
+|Kill Newcol Tutor Debug NextColor Dump Find Grep Help
+|  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  NOR /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 EXTERNAL
+|     2                                              sub  w.txt                                        sub  w.txt
+|
+|
+|
+|                                                      w.txt
 |
 |
 |
@@ -29,16 +46,29 @@
 |
 |
 |
-== snap reloaded grid=150x30 cursor=54,5
+|  NOR /tmp/pardes-snap/filewatch/cwd/sub/s.txt Sav  NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 line 1
+|     2 line 2                                       sub  w.txt
+|     3 line 3
+|     4 line 4
+|     5 line 5
+|     6 line 6
+|     7 line 7
+|     8 line 8
+|     9
+|
+|
+|
+|
+== snap reloaded_sub grid=150x30 cursor=15,2
 |Kill Newcol Tutor Debug NextColor Dump Find Grep Help
-|  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  TTY /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
-|     1 EXTERNAL                                     $ ls
-|     2                                              w.txt                                             w.txt
-|                                                    $ echo EXTERN''AL > w.txt
-|                                                    $
+|  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  NOR /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 EXTERNAL
+|     2                                              sub  w.txt                                        sub  w.txt
 |
 |
 |
+|                                                      w.txt
 |
 |
 |
@@ -46,9 +76,10 @@
 |
 |
 |
-|                                                    NOR /tmp/pardes-snap/filewatch/cwd Del
 |
-|                                                    w.txt
+|  NOR /tmp/pardes-snap/filewatch/cwd/sub/s.txt Sav  NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 RENAMED
+|     2                                              sub  w.txt
 |
 |
 |
@@ -62,13 +93,13 @@
 |
 == snap undone grid=150x30 cursor=15,2
 |Kill Newcol Tutor Debug NextColor Dump Find Grep Help
-|  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  TTY /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
-|     1 liMYEDITne 1                                 $ ls
-|     2 line 2                                       w.txt                                             w.txt
-|     3 line 3                                       $ echo EXTERN''AL > w.txt
-|     4 line 4                                       $
+|  NOR /tmp/pardes-snap/filewatch/cwd/w.txt Save De  NOR /tmp/pardes-snap/filewatch/cwd Del            NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 liMYEDITne 1
+|     2 line 2                                       sub  w.txt                                        sub  w.txt
+|     3 /tmp/pardes-snap/filewatch/cwd/sub/s.txt
+|     4 line 4
 |     5 line 5
-|     6 line 6
+|     6 line 6                                         w.txt
 |     7 line 7
 |     8 line 8
 |     9 line 9
@@ -77,9 +108,9 @@
 |    12 line 12
 |    13
 |
-|                                                    NOR /tmp/pardes-snap/filewatch/cwd Del
-|
-|                                                    w.txt
+|  NOR /tmp/pardes-snap/filewatch/cwd/sub/s.txt Sav  NOR /tmp/pardes-snap/filewatch/cwd Del
+|     1 RENAMED
+|     2                                              sub  w.txt
 |
 |
 |
diff --git a/test/snapshots/filewatch.snap b/test/snapshots/filewatch.snap
index 1ac8d081..6f1f2976 100644
--- a/test/snapshots/filewatch.snap
+++ b/test/snapshots/filewatch.snap
@@ -1,7 +1,23 @@
 # external file updates: a write from outside pardes lands in the open pane,
 # and Undo brings the unsaved edit back. That is the whole contract — the
 # update is committed like any other edit, so nothing has to be merged.
-lines w.txt 12
+#
+# The writer must be a STRANGER to the editor. This script used to have a
+# pardes PANE run the write, which proved much less than it looked: that
+# shell's own pty output wakes the loop and paints a frame, so the reload
+# could be riding on the keystroke's frame instead of on the watch. `run` is a
+# child of the RUNNER — nothing it does reaches an app pty — and every
+# assertion below it is a `wait`, which only READS the pty. So between the
+# write and the reload the app receives no keystroke, no resize, no mouse: if
+# the watch does not wake the loop by itself, these waits time out.
+#
+# Two files in two directories, written the two ways files actually change:
+# w.txt in place (CLOSE_WRITE) and sub/s.txt by rename-over, which is what
+# `zig fmt`, `git checkout` and every editor's atomic save do (MOVED_TO, and
+# a new inode — the reason the mark is on the directory).
+dirmk sub
+file w.txt line 1\nline 2\n/tmp/pardes-snap/filewatch/cwd/sub/s.txt\nline 4\nline 5\nline 6\nline 7\nline 8\nline 9\nline 10\nline 11\nline 12\n
+lines sub/s.txt 8
 start 30 150 -n 3
 wait 8000 w.txt
 stable 700 20000
@@ -15,9 +31,15 @@ key esc
 settle 100
 press right 6 8
 release right 6 8
-wait 10000 line 3
+wait 10000 line 4
 stable 700 15000
-# an UNSAVED edit on line 1
+# ...and open sub/s.txt from the path sitting on line 3 of that pane, so the
+# second watched pane is in a DIFFERENT directory from the first
+press right 20 5
+release right 20 5
+wait 10000 line 8
+stable 700 15000
+# an UNSAVED edit on line 1 of w.txt
 press left 10 3
 release left 10 3
 stable 400 5000
@@ -27,18 +49,15 @@ key esc
 settle 100
 stable 400 5000
 snap edited
-# overwrite the file from a shell in another column. The marker is split so
-# the ECHOED command line never matches the wait — only the reloaded pane does
-press left 60 5
-release left 60 5
-stable 400 5000
-key c-b
-stable 600 8000
-text echo EXTERN''AL > w.txt
-key enter
+# ---- from here to `snap reloaded_sub`, pardes is sent NOTHING ----
+run printf 'EXTERNAL\n' > w.txt
 wait 10000 EXTERNAL
 stable 700 10000
 snap reloaded
+run printf 'RENAMED\n' > sub/t && mv sub/t sub/s.txt
+wait 10000 RENAMED
+stable 700 10000
+snap reloaded_sub
 # back in the file pane: one undo and the unsaved edit is there again
 press left 10 3
 release left 10 3