1 files changed, 18 insertions, 1 deletions

diff --git a/src/gui/gui.zig b/src/gui/gui.zig
index 82866a30..f36de939 100644
--- a/src/gui/gui.zig
+++ b/src/gui/gui.zig
@@ -1512,6 +1512,8 @@ fn runNative(init: std.process.Init, opts_in: pardes.Options) !void {
     defer for (&ptys) |*slot| if (slot.*) |pt| {
         _ = libc.close(pt.fd);
     };
+    // the core's one way to ask about those ptys, pulled at the Exec that cares
+    core.tty_query = .{ .ctx = &ptys, .taken = &ttyTakenAt };
     var lsp_workers: LspWorkers = .{};
     var queue: Queue = .{
         .gpa = gpa,
@@ -2062,6 +2064,7 @@ fn runGrid(init: std.process.Init, opts_in: pardes.Options) !void {
     defer for (&ptys) |*slot| if (slot.*) |pt| {
         _ = libc.close(pt.fd);
     };
+    core.tty_query = .{ .ctx = &ptys, .taken = &ttyTakenAt };
     var lsp_workers: LspWorkers = .{};
     var queue: Queue = .{
         .gpa = gpa,
@@ -2908,7 +2911,8 @@ fn drainEffects(
             }
             const pt = forkShell(core.shellBin(), cwd_z, core.screen_h, core.screen_w);
             ptys[sp.pane] = pt;
-            // report the pane's starting directory back to the core (tags)
+            // report the pane's starting directory back to the core (tags); the
+            // slot needs no occupancy reset, nothing about it is remembered
             var lbuf: [1024]u8 = undefined;
             if (look.shellCwd(pt.pid, &lbuf)) |wd| core.setCwd(sp.pane, wd);
             if (threads_ok) spawnReader(gpa, pt, sp.pane, gens[sp.pane], queue);
@@ -3014,6 +3018,9 @@ fn forkShell(bin: []const u8, cwd: ?[*:0]const u8, rows: u16, cols: u16) Pty {
     return .{ .fd = master, .pid = pid };
 }
 
+/// Live cwd for tags/look: a cheap per-pane process lookup, polled every frame
+/// because a tagline draws it. Whether a pane's tty still belongs to the prompt
+/// pardes forked is deliberately NOT polled with it — see `ttyTakenAt`.
 fn pollCwds(core: *pardes.Pardes, ptys: *[pardes.MAX_PANES]?Pty) void {
     for (ptys, 0..) |slot, id| if (slot) |pt| {
         var lbuf: [1024]u8 = undefined;
@@ -3021,6 +3028,16 @@ fn pollCwds(core: *pardes.Pardes, ptys: *[pardes.MAX_PANES]?Pty) void {
     };
 }
 
+/// The core's `tty_query`: is a program (vim, a pager, an agent) holding this
+/// pane's tty instead of the shell we forked? Asked by the core only where it is
+/// about to type a command line, which is why the /proc walk behind it is not in
+/// pollCwds above: nothing draws this answer, and an Exec is a rare frame.
+fn ttyTakenAt(ctx: ?*anyopaque, pane: usize) bool {
+    const table: *const [pardes.MAX_PANES]?Pty = @ptrCast(@alignCast(ctx orelse return false));
+    const pt = table[pane] orelse return false;
+    return look.ttyTaken(pt.pid, pt.fd);
+}
+
 /// web: no ptys, no fs — panes replay from the embedded dump. Only the
 /// clipboard and open_link effects have a browser meaning.
 fn drainEffectsWeb(core: *pardes.Pardes, gpa: std.mem.Allocator, g: *Gui) void {