fix: sesh channel fixes and inherit TTY fds for interactive actions (#1052)

Closes joshmedeski/sesh#368

- Fix an interaction between \`tv\`'s execute actions and \`tmux
attach-session\` on macOS that surfaces as \`open terminal failed: can't
use /dev/tty\` when an action shells out to tmux from outside a running
tmux client.
- Let \`sesh\` (and other session managers) manage their own ordering by
adding \`frecency = false\` / \`no_sort = true\` to the built-in
\`sesh\` channel, and tidy a couple of formatting nits in
\`cable/unix/sesh.toml\`.

## The TTY bug

\`attach_to_tty\` in \`television/utils/command.rs\` unconditionally
reopens \`/dev/tty\` and dup's the resulting FD onto the child's
stdin/stdout/stderr before every execute/fork action. That behaviour is
necessary when \`tv\` is invoked with piped streams (\`ls | tv --preview
...\`), but in the normal interactive case it hands the child a file
descriptor whose kernel path is \`/dev/tty\`.

On macOS, \`ttyname()\` on such an FD resolves back to \`/dev/tty\`
rather than to the underlying pty device (e.g. \`/dev/ttys001\`). When
the child eventually runs \`tmux attach-session\`, tmux's client code
rejects that path in \`tty.c\` — it explicitly refuses \`/dev/tty\`
because it needs an unambiguous, openable device — and exits 1. The user
sees:

\`\`\`
open terminal failed: can't use /dev/tty

   ERROR

  Failed to attach to tmux session: exit status 1.
\`\`\`

Running the exact same \`sesh connect <session>\` command from the same
shell (fish/zsh/bash) outside of \`tv\` works fine, because the shell's
stdin is the real pty slave, not a dup of \`/dev/tty\`. That's the tell
that the issue lives in \`attach_to_tty\`, not in sesh/tmux.

This only surfaces now because previously the path most people hit was
\`tv sesh\` from inside tmux, which takes the \`tmux switch-client\`
branch in sesh — \`switch-client\` is a non-interactive tmux subcommand
and tolerates any FD that \`isatty()\` accepts, so the bug stays hidden.

### The fix

Check whether the inherited stdin/stdout/stderr are already TTYs (via
\`std::io::IsTerminal\`, no new dependencies). If so, inherit them as-is
so the child sees the real pty device path. Otherwise fall through to
the existing \`/dev/tty\` fallback so piped invocations keep working.

Before calling \`execute_action\`, \`tv\` already tears down its TUI
(\`RenderingTask::Quit\`, \`disable_raw_mode\`, etc. in \`app.rs\`), so
the inherited FDs are in cooked mode — safe to pass through.

## Channel config tweak

The \`sesh\` channel now sets:

\`\`\`toml
frecency = false # handled by sesh
no_sort = true   # handled by sesh
\`\`\`

\`sesh list\` already returns sessions in the order users expect
(recently-used tmux sessions first, then config/zoxide entries).
Layering \`tv\`'s frecency and default sort on top of that reorders the
list in confusing ways — better to defer to sesh.

Also reflowed the \`command = [...]\` array and the \`ctrl-d\` binding
to match the formatter's output.

## Test plan

- [x] \`cargo check --lib\` clean
- [x] \`cargo build\` clean (debug binary exercised manually)
- [x] \`tv sesh\` from outside tmux (server running, no attached client)
attaches to an existing session and returns cleanly on detach
- [x] \`tv sesh\` from inside tmux still switches (unchanged path)
- [ ] \`ls | tv\` style piped invocation — \`/dev/tty\` fallback still
engaged; preview/actions still usable
- [ ] Linux sanity check (macOS-specific symptom, but the fix is
portable)

The test suite wasn't run because \`libghostty-vt-sys\` in this checkout
requires zig 0.15.2 while my local zig is 0.16.0 — unrelated to this
change.

---------

Co-authored-by: Alex Pasmantier <47638216+alexpasmantier@users.noreply.github.com>

Author: joshmedeski

cable/unix/sesh.toml

@@ -10,21 +10,23 @@ requirements = ["sesh", "fd"]
 # Multiple source commands for cycling through different modes
 # Press Ctrl+S to cycle between sources
 command = [
-  "sesh list --icons",                          # all sessions (default)
-  "sesh list -t --icons",                       # tmux sessions only
-  "sesh list -c --icons",                       # config directories
-  "sesh list -z --icons",                       # zoxide directories
-  "fd -H -d 2 -t d -E .Trash . ~"               # find directories
+  "sesh list --icons",             # all sessions (default)
+  "sesh list -t --icons",          # tmux sessions only
+  "sesh list -c --icons",          # config directories
+  "sesh list -z --icons",          # zoxide directories
+  "fd -H -d 2 -t d -E .Trash . ~", # find directories
 ]
 ansi = true
+frecency = false # handled by sesh
+no_sort = true # handled by sesh
 output = "{strip_ansi|split: :1..|join: }"
 
 [preview]
 command = "sesh preview '{strip_ansi|split: :1..|join: }'"
 
 [keybindings]
 enter = "actions:connect"
-ctrl-d = [ "actions:kill_session", "reload_source" ]
+ctrl-d = ["actions:kill_session", "reload_source"]
 
 [actions.connect]
 description = "Connect to selected session"

television/utils/command.rs

@@ -204,6 +204,20 @@ pub fn execute_action(
 
 #[cfg(unix)]
 fn attach_to_tty(cmd: &mut Command) -> Result<()> {
+    use std::io::{IsTerminal, stderr, stdin, stdout};
+
+    // If stdin/stdout/stderr are already real TTYs (interactive invocation),
+    // inherit them as-is. Reopening `/dev/tty` and dup'ing the resulting FD
+    // produces a file descriptor whose ttyname resolves to `/dev/tty` on
+    // macOS, which tmux rejects with "can't use /dev/tty" when attaching.
+    // Inheriting the original pty FDs preserves the real device path.
+    if stdin().is_terminal()
+        && stdout().is_terminal()
+        && stderr().is_terminal()
+    {
+        return Ok(());
+    }
+
     let Ok(tty) = OpenOptions::new().read(true).write(true).open("/dev/tty")
     else {
         return Ok(());