feat: add sesh window command for tmux window management

[fenngwd]

Summary

Closes #282

Adds a new sesh window (alias w) subcommand for listing and managing tmux windows within a session, mirroring the UX of sesh list and sesh connect.

Features

• sesh window — list all windows in the current tmux session (one per line)
• sesh window <name> — switch to an existing window by name
• sesh window <path> — create a new window at the given directory (name = basename)
• --session / -s flag to target a session other than the current one
• --json / -j flag reserved for JSON output in list mode

Implementation

• model/tmux_window.go — new TmuxWindow data type (Name, Path, Index, Active)
• tmux/list_tmux_win.go + tests — ListWindows(targetSession string) using tmux list-windows
• tmux/select_win.go + tests — SelectWindow(name string) using tmux select-window
• seshcli/window.go — cobra command wired to the above
• seshcli/root_command.go — registered in root command

Note: files are named list_tmux_win.go / select_win.go (not list_windows.go / select_window.go) to avoid Go's platform-specific build constraint, which treats files ending in _windows.go as Windows-only.

Testing

Unit tests follow the same mock-based pattern as the existing tmux package tests. All 14 packages pass.

[joshmedeski]

Just to clarify, how would this feature be used?

Can you clarify it's purpose in the README and some basic instructions for how to use it, thanks.

[Copilot]

Pull request overview

Adds a new sesh window / sesh w command to list, switch to, and create tmux windows within a session, aligning window UX with existing session-oriented commands.

Changes:

• Introduces model.TmuxWindow and tmux-layer support for listing windows and selecting a window.
• Adds a new Cobra command sesh window and registers it in the root command.
• Adds unit tests for the new tmux window list/select functions.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
tmux/tmux.go	Extends the Tmux interface with window list/select capabilities needed by the CLI.
tmux/list_tmux_win.go	Implements ListWindows() using tmux list-windows parsing into TmuxWindow.
tmux/list_tmux_win_test.go	Adds tests for window listing, target session flag behavior, and parsing.
tmux/select_win.go	Implements SelectWindow() using tmux select-window.
tmux/select_win_test.go	Adds a unit test ensuring the correct tmux command is executed.
model/tmux_window.go	Adds the window model used across tmux + CLI layers.
seshcli/window.go	Introduces the window subcommand wiring together list/select/create behaviors.
seshcli/root_command.go	Registers the new window command at the root.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

This command shells out directly via base.Shell.Cmd("tmux", ...) to create a window, bypassing the tmux.Tmux abstraction. That makes the CLI harder to unit test (no tmux mock) and duplicates tmux command construction outside the tmux package. Consider adding a tmux-layer method that supports creating a window in an optional target session (e.g., extend NewWindow or add NewWindowInSession) and calling that instead.

Suggested change

	newWindowArgs := []string{"new-window", "-n", windowName, "-c", absPath}
	if targetSession != "" {
	newWindowArgs = append(newWindowArgs, "-t", targetSession)
	}
	if _, err := base.Shell.Cmd("tmux", newWindowArgs...); err != nil {
	if _, err := base.Tmux.NewWindowInSession(windowName, absPath, targetSession); err != nil {

[Copilot]

ListWindows swallows errors from t.shell.ListCmd and returns an empty slice with a nil error. This makes it impossible for callers to distinguish between “no windows” and a real failure (e.g., tmux not available, permission issues, malformed args). Consider returning the original err (or only suppressing the specific 'no server running' case) so CLI code can surface failures appropriately.

Suggested change

	return []*model.TmuxWindow{}, nil
	return nil, err

[Copilot]

The SelectWindow method parameter is named name, but callers can pass a full tmux target like session:window (see seshcli/window.go). Renaming the parameter to something like target/targetWindow would better reflect actual usage and reduce confusion for future callers.

Suggested change

	SelectWindow(name string) (string, error)
	SelectWindow(targetWindow string) (string, error)

[Copilot]

The --json/-j flag is parsed but intentionally ignored (_ = jsonOutput), so users can enable it with no observable effect. Either implement JSON output for list mode or return a clear error when --json is provided to avoid a silent no-op.

[fenngwd]

Thanks for the feedback! I've added a Window management section to the README with examples covering:

• Listing windows in the current session
• Switching to an existing window by name
• Creating a new window at a directory path
• Targeting a different session with --session
• fzf integration example

I also addressed the 4 Copilot review suggestions in the latest commit:

• Added NewWindowInSession to the tmux package (instead of calling Shell.Cmd directly from the CLI layer)
• ListWindows now returns errors instead of swallowing them
• Renamed SelectWindow parameter to targetWindow for clarity
• Implemented --json output for list mode