Text sent to a REPL is plain lines, sent whole or not at all

A CRLF became two line ends, the blank line ending a Python block; an ESC in
the text, ESC[201~ above all, could end a bracketed paste early; and on the
board, whose writes are 128 effects of 64 bytes with nothing pending, a send
past 8 KB was cut and lost its closing ESC[201~ and Enter, leaving the REPL
in a paste. Lines now end in LF alone, ESC and every control byte but tab and
newline are dropped, and a send larger than can be written at once
(Pardes.writeRoom) is refused with a message instead of cut.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/src/pardes.zig b/src/pardes.zig
index 64c05fff..85eae10f 100644
--- a/src/pardes.zig
+++ b/src/pardes.zig
@@ -1487,6 +1487,10 @@ test "a REPL bound for a language takes the exec made on a body in it; tags, Exe
         var line: [ctlfs.ctl.pane_text_cap]u8 = undefined;
         try std.testing.expect(std.mem.endsWith(u8, ctlfs.ctl.paneText(p, p.panes[1].?, &line), " python-a "));
     }
+    // What is sent is plain text: CRLF is LF, no ESC or other control.
+    _ = exec.executeFrom(p, 0, "a = 1\r\nb = \x1b[201~2", true);
+    Sent.drain(p);
+    try std.testing.expectEqualStrings("a = 1\rb = [201~2\r", Sent.said(1));
     // Several selections executed at once: each is sent, not the first.
     {
         const text = try edit.flatSurface(p, &file.body);
@@ -4626,6 +4630,14 @@ pub const Pardes = struct {
         if (off < bytes.len) p.parkPendingWrite(id, bytes[off..]);
     }
 
+    /// How many bytes `emitWrite` can take for pane `id` now without
+    /// dropping any: the effects left, then what the pending buffer holds.
+    pub fn writeRoom(p: *const Pardes, id: usize) usize {
+        const pending = limits.pending_write_cap -| p.pending_write_bytes;
+        if (p.pending_write[id] != null) return pending;
+        return (p.effects.len - p.effects_len) * 64 + pending;
+    }
+
     fn parkPendingWrite(p: *Pardes, id: usize, bytes: []const u8) void {
         if (comptime limits.pending_write_cap == 0) return;
         if (p.pending_write_bytes + bytes.len > limits.pending_write_cap) return;