package session

import (
	"github.com/warrenronsiek/ctask/internal/shell"
)

// attacher is the test seam used by AttachExisting. Production code calls
// shell.AttachSession directly; tests override this variable to capture
// invocations or simulate failures. Do not run tests that override this
// variable in parallel — it is a package global.
var attacher = shell.AttachSession

// AttachExisting is the passive-reattach path. It is invoked when a tmux
// session for the workspace already exists and the lease is fresh and local
// (the original ctask owner is alive and heartbeating).
//
// AttachExisting performs no Preflight, writes no lease, captures no
// manifest, starts no heartbeat, prints no banner, and runs no finalize.
// It connects the user's terminal to the existing tmux session via
// shell.AttachSession and returns when the user detaches or the session
// ends. shell.AttachSession's contract handles failure-mode classification:
// nil on clean exit, wrapped error on non-zero exit.
//
// If the session disappeared between the dispatcher's HasSession check
// and this call, AttachSession returns an error and the user can retry —
// the next invocation will hit the owner-create path.
func AttachExisting(tmuxPath, name string) error {
	return attacher(tmuxPath, name)
}