A desktop session holds 64 panes, and every route that finds none free says so

Sixteen panes was far too few for a real session. MAX_PANES is now 64 on a
desktop and stays 16 on the board; the 48 more slots cost about 3.7 KB each
in fixed tables (the core 1.33 to 1.45 MB, its surface 19 to 72 KB), and a
pane itself (84 KB and its terminal) is allocated only when it opens. At the
cap, pane/new fails with `pane/new: no pane slots: 64 max` and an err
record rather than a bare ENFILE, a 9P look or exec that would open a pane
fails its write with the same words and reads back empty, and New, Tty,
Tutor and Alt-n say it on the message row (their ctl writes fail with it).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 8 insertions, 4 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index 8dbe6744..a6a088de 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -250,7 +250,11 @@ pub const pdf_raster_policy: PdfRasterPolicy = switch (platform) {
 pub const Pane = panes.Pane;
 const Text = panes.Text;
 
-pub const MAX_PANES = 16;
+/// Pane slots: 64 on a desktop, where a session keeps many files and
+/// terminals open; the board keeps its 16. A slot costs its share of the
+/// fixed tables (MAX_PANES-sized arrays in the core and its surface) whether
+/// or not a pane is in it; a pane itself is allocated when it opens.
+pub const MAX_PANES = if (platform == .esp32p4) 16 else 64;
 pub const Layer = @import("Layer.zig");
 pub const RowMetrics = Layer.Metrics;
 pub const TagHit = Layer.TagHit;
@@ -4797,7 +4801,7 @@ pub const Pardes = struct {
 
     /// A scratch for New (`.scratch`) or 9P's pane/new (`.fs`).
     pub fn newScratchFor(p: *Pardes, from_id: usize, kind: exec.NewPane) void {
-        const free = p.freeSlot() orelse return;
+        const free = p.freeSlot() orelse return p.reportError(from_id, "New", error.NoPaneSlots);
         _ = p.newScratch(from_id, free) catch return;
         exec.placeNew(p, from_id, from_id, free, kind);
     }
@@ -5305,7 +5309,7 @@ pub const Pardes = struct {
         p.raw_hover_intent = false;
         look.cancelLookHover(p);
         const reply = ctlfs.handle(p, req);
-        if (reply.status == .err and (req.op == .write or req.op == .setattr)) ctlfs.events.noteError(p, req, reply);
+        if (reply.status == .err and (req.op == .write or req.op == .setattr or (req.op == .open and reply.errno == ctlfs.E.NFILE))) ctlfs.events.noteError(p, req, reply);
         // The request was a whole step of its own, so it settles the way a
         // step does: the cursor and scroll reconciled, the scripted panes
         // told, and the panes it made announced to /log now rather than at
@@ -5665,7 +5669,7 @@ pub const Pardes = struct {
         // global window ops (any mode): Alt-n new terminal below, Alt-c move
         // the active terminal into a fresh column
         if (hit(key, config.new_shell_below)) {
-            const free = p.freeSlot() orelse return;
+            const free = p.freeSlot() orelse return p.reportError(p.active, "Tty", error.NoPaneSlots);
             const nt = p.newShell(free, "") catch return;
             nt.greet = true;
             // From a tag, as a 9P new is: acme's t->w == nil.