1 files changed, 49 insertions, 0 deletions
diff --git a/src/selection_pipe.zig b/src/selection_pipe.zig
index 65c4c7fd..c1104010 100644
--- a/src/selection_pipe.zig
+++ b/src/selection_pipe.zig
@@ -78,6 +78,55 @@ pub const Response = struct {
     }
 };
 
+/// The in-flight set a host keeps while pipes run off its loop.
+///
+/// tty.zig and gui.zig each had this verbatim — same `finish` walk, same
+/// `cancelAll`, same 16 — differing only in whether `add` asserted or returned
+/// a bool. It lives here beside the Job it tracks so a third host (the AppKit
+/// shell, which had no pipe support at all) does not have to grow a fourth.
+///
+/// Bounded on purpose: a filter is a user gesture, and sixteen concurrent ones
+/// is already more than anybody means. `add` returning false is the host's cue
+/// to answer the request as failed rather than to queue it.
+pub const Tasks = struct {
+    pub const capacity = 16;
+
+    pub const Task = struct {
+        id: u32,
+        future: std.Io.Future(anyerror!void),
+    };
+
+    items: [capacity]Task = undefined,
+    len: usize = 0,
+
+    pub fn full(tasks: *const Tasks) bool {
+        return tasks.len == tasks.items.len;
+    }
+
+    pub fn add(tasks: *Tasks, task: Task) bool {
+        if (tasks.full()) return false;
+        tasks.items[tasks.len] = task;
+        tasks.len += 1;
+        return true;
+    }
+
+    /// Join the one that answered and drop it, preserving order so `cancelAll`
+    /// stays deterministic.
+    pub fn finish(tasks: *Tasks, io: std.Io, id: u32) void {
+        for (tasks.items[0..tasks.len], 0..) |*task, i| if (task.id == id) {
+            task.future.await(io) catch {};
+            tasks.len -= 1;
+            std.mem.copyForwards(Task, tasks.items[i..tasks.len], tasks.items[i + 1 .. tasks.len + 1]);
+            return;
+        };
+    }
+
+    pub fn cancelAll(tasks: *Tasks, io: std.Io) void {
+        for (tasks.items[0..tasks.len]) |*task| task.future.cancel(io) catch {};
+        tasks.len = 0;
+    }
+};
+
 const WriterContext = struct {
     io: std.Io,
     file: std.Io.File,