From 7171ad1905fc492a106617e2c917ce4e79fa9baa Mon Sep 17 00:00:00 2001
From: CJ van den Berg <cj@vdbonline.com>
Date: Mon, 30 Mar 2026 21:46:08 +0200
Subject: [PATCH] fix(kqueue): fix handling of move-in subdirs

---
 src/backend/KQueue.zig    | 10 ++++++++++
 src/backend/KQueueDir.zig | 18 +++++++++++++++---
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/backend/KQueue.zig b/src/backend/KQueue.zig
index 542031c..8f3e717 100644
--- a/src/backend/KQueue.zig
+++ b/src/backend/KQueue.zig
@@ -171,6 +171,9 @@ fn thread_fn(self: *@This(), allocator: std.mem.Allocator) void {
                     std.log.err("nightwatch: handler returned {s}, stopping watch thread", .{@errorName(e)});
                     return;
                 };
+                // Clean up snapshot so that a new dir at the same path is not
+                // skipped by scan_dir's snapshots.contains() check.
+                self.remove_watch(allocator, dir_path);
             } else if (ev.fflags & NOTE_RENAME != 0) {
                 self.handler.change(dir_path, EventType.renamed, .dir) catch |e| {
                     std.log.err("nightwatch: handler returned {s}, stopping watch thread", .{@errorName(e)});
@@ -285,6 +288,10 @@ fn scan_dir(self: *@This(), allocator: std.mem.Allocator, dir_path: []const u8)
     // a rename (old disappears, new appears) reports the source path before the dest.
     for (new_dirs.items) |full_path| {
         try self.handler.change(full_path, EventType.created, .dir);
+        // Start watching the moved-in dir so future changes inside it are detected
+        // and so its deletion fires NOTE_DELETE rather than being silently missed.
+        self.add_watch(allocator, full_path) catch |e|
+            std.log.err("nightwatch: add_watch on moved-in dir failed: {s}", .{@errorName(e)});
         try self.emit_subtree_created(allocator, full_path);
     }
     for (to_delete.items) |name| {
@@ -322,6 +329,9 @@ fn emit_subtree_created(self: *@This(), allocator: std.mem.Allocator, dir_path:
         if (ot == .file) {
             self.register_file_watch(allocator, full_path);
         } else {
+            // Watch nested subdirs so changes inside them are detected after move-in.
+            self.add_watch(allocator, full_path) catch |e|
+                std.log.err("nightwatch: add_watch on moved-in subdir failed: {s}", .{@errorName(e)});
             try self.emit_subtree_created(allocator, full_path);
         }
     }
diff --git a/src/backend/KQueueDir.zig b/src/backend/KQueueDir.zig
index be082e7..ca95d63 100644
--- a/src/backend/KQueueDir.zig
+++ b/src/backend/KQueueDir.zig
@@ -152,6 +152,9 @@ fn thread_fn(self: *@This(), allocator: std.mem.Allocator) void {
                         std.log.err("nightwatch: handler returned {s}, stopping watch thread", .{@errorName(e)});
                         return;
                     };
+                    // Clean up snapshot so that a new dir at the same path is not
+                    // skipped by scan_dir's snapshots.contains() check.
+                    self.remove_watch(allocator, watch_path);
                 } else if (ev.fflags & NOTE_RENAME != 0) {
                     self.handler.change(watch_path, EventType.renamed, .dir) catch |e| {
                         std.log.err("nightwatch: handler returned {s}, stopping watch thread", .{@errorName(e)});
@@ -279,7 +282,11 @@ fn scan_dir(self: *@This(), allocator: std.mem.Allocator, dir_path: []const u8)
     // Order: new dirs, deletions (source before dest for renames), creations, modifications.
     for (new_dirs.items) |full_path| {
         try self.handler.change(full_path, EventType.created, .dir);
-        try self.emit_subtree_created(full_path);
+        // Start watching the moved-in dir so future changes inside it are detected
+        // and so its deletion fires NOTE_DELETE rather than being silently missed.
+        self.add_watch(allocator, full_path) catch |e|
+            std.log.err("nightwatch: add_watch on moved-in dir failed: {s}", .{@errorName(e)});
+        try self.emit_subtree_created(allocator, full_path);
     }
     for (to_delete.items) |name| {
         var path_buf: [std.fs.max_path_bytes]u8 = undefined;
@@ -302,7 +309,7 @@ fn scan_dir(self: *@This(), allocator: std.mem.Allocator, dir_path: []const u8)
 // Walk dir_path recursively, emitting 'created' events for all contents.
 // Called after a new dir appears in scan_dir so callers see individual
 // 'created' events for the pre-existing tree of a moved-in directory.
-fn emit_subtree_created(self: *@This(), dir_path: []const u8) error{HandlerFailed}!void {
+fn emit_subtree_created(self: *@This(), allocator: std.mem.Allocator, dir_path: []const u8) !void {
     var dir = std.fs.openDirAbsolute(dir_path, .{ .iterate = true }) catch return;
     defer dir.close();
     var iter = dir.iterate();
@@ -315,7 +322,12 @@ fn emit_subtree_created(self: *@This(), dir_path: []const u8) error{HandlerFaile
         var path_buf: [std.fs.max_path_bytes]u8 = undefined;
         const full_path = std.fmt.bufPrint(&path_buf, "{s}/{s}", .{ dir_path, entry.name }) catch continue;
         try self.handler.change(full_path, EventType.created, ot);
-        if (ot == .dir) try self.emit_subtree_created(full_path);
+        if (ot == .dir) {
+            // Watch nested subdirs so changes inside them are detected after move-in.
+            self.add_watch(allocator, full_path) catch |e|
+                std.log.err("nightwatch: add_watch on moved-in subdir failed: {s}", .{@errorName(e)});
+            try self.emit_subtree_created(allocator, full_path);
+        }
     }
 }