pardes FILE in a pane whose session answers never falls back to a nested editor: the refusal is printed, exit 1, and no stray pane is left

When the environment named a live session that answered, several
failures broke out of forwarding and started a whole editor inside the
pane that asked: a refused name, a pane the session has not, a failed look
write. Its screen was drawn over the shell. Now, once the session answers
(Client.probe), every refusal is printed as `pardes: <file>: <why>`, in
the session's own words (the Rerror, now kept by the client), and the
launch exits 1, as acme's B does. A new name the session refuses deletes
the pane made for it, so no empty +New is left. A missing environment or a
session that does not answer still starts a separate editor. fs.py checks
a refused name and a stale PARDES_PANE.

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

1 files changed, 15 insertions, 2 deletions

diff --git a/src/9p_io.zig b/src/9p_io.zig
index d1b2099c..5a68238c 100644
--- a/src/9p_io.zig
+++ b/src/9p_io.zig
@@ -1808,7 +1808,17 @@ pub const Client = struct {
         var sock_buf: [sun_path_len]u8 = undefined;
         const sock = try resolve(&sock_buf, dial);
         var remote: RemoteError = .{};
-        return fetchBytes(gpa, sock, names[0..n], &remote, null, display_path, @min(max_bytes, limits.max_file_bytes));
+        return fetchBytes(gpa, sock, names[0..n], &remote, null, display_path, @min(max_bytes, limits.max_file_bytes)) catch |err| {
+            if (err == error.Remote) said = remote;
+            return err;
+        };
+    }
+
+    /// The peer's own words for the last error.Remote a read or write here
+    /// got (its Rerror), for a caller that says why.
+    var said: RemoteError = .{};
+    pub fn lastSaid() []const u8 {
+        return said.buf[0..said.len];
     }
 
     /// Whether a peer answers at `dial`: a version and attach, and its root
@@ -1828,7 +1838,10 @@ pub const Client = struct {
         var sock_buf: [sun_path_len]u8 = undefined;
         const sock = try resolve(&sock_buf, dial);
         var remote: RemoteError = .{};
-        const result = try fetchBytes(gpa, sock, names[0..n], &remote, bytes, path, limits.max_file_bytes);
+        const result = fetchBytes(gpa, sock, names[0..n], &remote, bytes, path, limits.max_file_bytes) catch |err| {
+            if (err == error.Remote) said = remote;
+            return err;
+        };
         gpa.free(result);
     }