1 files changed, 55 insertions, 3 deletions

diff --git a/src/file_watch.zig b/src/file_watch.zig
index 5d998470..d028488e 100644
--- a/src/file_watch.zig
+++ b/src/file_watch.zig
@@ -60,6 +60,10 @@ pub const Watch = struct {
     kq: c_int = -1,
     serial: u32,
     generation: Generation,
+    /// The path last read while watched (its hash): its going away later is
+    /// a deletion to say, where a path never there (a pane renamed to a new
+    /// name) is not.
+    existed: ?u64 = null,
 };
 
 /// The final slot is the one non-pane watched payload: the active ThemeFile.
@@ -221,8 +225,10 @@ fn markDir(fd: c_int, dir_z: [:0]const u8, watches: *const Table) c_int {
     switch (builtin.os.tag) {
         .linux => {
             // CLOSE_WRITE coalesces one writer's writes; MOVED_TO and CREATE
-            // cover rename-over and delete-then-recreate saves.
-            const mask = linux.IN.CLOSE_WRITE | linux.IN.MOVED_TO | linux.IN.CREATE | linux.IN.ONLYDIR;
+            // cover rename-over and delete-then-recreate saves; DELETE and
+            // MOVED_FROM a file going away, said at once (File.deleted), not
+            // when something else next changes in the directory.
+            const mask = linux.IN.CLOSE_WRITE | linux.IN.MOVED_TO | linux.IN.CREATE | linux.IN.DELETE | linux.IN.MOVED_FROM | linux.IN.ONLYDIR;
             return libc.inotify_add_watch(fd, dir_z, mask);
         },
         .macos => {
@@ -440,7 +446,12 @@ pub fn reloadPane(
     }
 
     if (pane.file) |file| {
-        const bytes = filesystem.read(core, file.path) catch return false;
+        const bytes = filesystem.read(core, file.path) catch |err| {
+            // Gone from under the pane: said once, the text kept.
+            if (err == error.FileNotFound and watched.existed == std.hash.Wyhash.hash(0, file.path)) pardes.panes.File.deleted(core, @intCast(id));
+            return false;
+        };
+        if (watches[id]) |*live| live.existed = std.hash.Wyhash.hash(0, file.path);
         defer core.gpa.free(bytes);
         const hash = std.hash.Wyhash.hash(0, bytes);
         switch (watched.generation) {
@@ -517,6 +528,7 @@ pub fn applyEffect(
         const bytes = filesystem.read(core, file.path) catch return false;
         defer core.gpa.free(bytes);
         watched.generation = .{ .text = std.hash.Wyhash.hash(0, bytes) };
+        watched.existed = std.hash.Wyhash.hash(0, file.path);
         return false;
     };
     return on and watches[id] != null and reloadPane(core, io, watches, id, false);
@@ -665,6 +677,13 @@ test "restored file watches preserve snapshots and accept later disk changes" {
 
         try tmp.dir.writeFile(io, .{ .sub_path = "watched", .data = "later disk save\n" });
         _ = reloadChanged(core, io, gpa, &watches);
+        // A snapshot restored with unsaved text keeps it: a later disk
+        // change is said, never loaded over it (File.changed).
+        if (case.dirty) {
+            try std.testing.expectEqualStrings("restored snapshot\n", pane.file.?.content);
+            try std.testing.expect(pane.file.?.disk_newer != null);
+            continue;
+        }
         try std.testing.expectEqualStrings("later disk save\n", pane.file.?.content);
         pardes.panes.File.undo(core, pane);
         try std.testing.expectEqualStrings("restored snapshot\n", pane.file.?.content);
@@ -821,3 +840,36 @@ test "theme watch reloads valid ZON and keeps the last theme across a bad save"
     try std.testing.expect(!reloadTheme(core, gpa, &watches, false));
     try std.testing.expectEqual(@as(?[3]u8, .{ 9, 8, 7 }), core.theme().bg);
 }
+
+test "a watched file deleted wakes the watch at once, and its pane says so" {
+    if (comptime !supported or !filesystem.platform_has_fs or builtin.os.tag != .linux) return;
+    const io = std.testing.io;
+    const gpa = std.testing.allocator;
+    var tmp = std.testing.tmpDir(.{});
+    defer tmp.cleanup();
+    try tmp.dir.writeFile(io, .{ .sub_path = "watched", .data = "here\n" });
+    var path_buf: [256]u8 = undefined;
+    const path = try std.fmt.bufPrint(&path_buf, ".zig-cache/tmp/{s}/watched", .{tmp.sub_path});
+    const core = try pardes.Pardes.init(gpa, .{ .tty_only = true });
+    defer core.deinit();
+    while (core.nextEffect()) |_| {}
+    const id: u8 = @intCast(core.freeSlot().?);
+    const pane = try pardes.panes.File.open(core, id, path, 0);
+    const fd = init(true);
+    if (fd < 0) return error.NoWatcher;
+    defer _ = libc.close(fd);
+    var watches: Table = @splat(null);
+    defer watchPane(fd, &watches, id, null, pane.serial, .{ .text = 0 });
+    while (core.nextEffect()) |effect| switch (effect) {
+        .watch => |watch| if (watch.pane == id and watch.on) {
+            _ = applyEffect(core, io, fd, &watches, id, watch.on, watch.mode);
+        },
+        else => {},
+    };
+    _ = drain(fd);
+    try tmp.dir.deleteFile(io, "watched");
+    var pfd = [_]libc.pollfd{.{ .fd = fd, .events = libc.POLL.IN, .revents = 0 }};
+    try std.testing.expect(libc.poll(&pfd, 1, 1000) > 0);
+    _ = reloadChanged(core, io, gpa, &watches);
+    try std.testing.expect(pane.file.?.disk_gone);
+}