diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index ab9125d..6295e9b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,7 +6,8 @@ repository.
 
 ## Prerequisites
 
-- **Go 1.24+** - the module declares `go 1.24` and CI runs on 1.24.
+- **Go** - the version declared in `go.mod` (CI builds with the same
+  version).
 - **tmux 3.1+** - required at runtime and for the integration test suite.
   `mox` uses tmux 3.1 features such as `split-window -l <n>%`.
 - **golangci-lint** - used by `make lint` and by CI. Install from
diff --git a/internal/cli/editor_state.go b/internal/cli/editor_state.go
index c8a7508..8f3859b 100644
--- a/internal/cli/editor_state.go
+++ b/internal/cli/editor_state.go
@@ -154,14 +154,15 @@ func (st *editorState) applyDraft(d *sessionDraft) error {
 
 	sessMap := findOrCreateMapKey(st.root.Content[0], "sessions")
 
-	// Guard against name collisions (I1: prevents duplicate keys in the map).
+	// A new or renamed session must not land on an existing key: yaml.v3
+	// refuses to decode a mapping with duplicate keys.
 	if !d.deleted && (d.orig == "" || d.name != d.orig) {
 		if findMapKey(sessMap, d.name) != nil {
 			return fmt.Errorf("session %q already exists", d.name)
 		}
 	}
 
-	// Snapshot the Content slice for rollback on write failure (C1).
+	// Snapshot Content so a failed write can roll the node tree back.
 	snapshot := make([]*yaml.Node, len(sessMap.Content))
 	copy(snapshot, sessMap.Content)
 	var didRename bool
@@ -171,7 +172,8 @@ func (st *editorState) applyDraft(d *sessionDraft) error {
 	case d.deleted:
 		removeMapKey(sessMap, d.orig)
 	default:
-		// M1: pure rename — only rename the key, don't re-encode the session body.
+		// Pure rename: rename the key only, so the body keeps its original
+		// formatting and comments instead of being re-encoded.
 		if d.orig != "" && d.name != d.orig && sameSessionYAML(d.sess, st.cfg.Sessions[d.orig]) {
 			didRename = true
 			origName = d.orig
diff --git a/internal/cli/editor_state_test.go b/internal/cli/editor_state_test.go
index 893375b..95fe510 100644
--- a/internal/cli/editor_state_test.go
+++ b/internal/cli/editor_state_test.go
@@ -191,7 +191,7 @@ func TestApplyDraftStaleBlocksWrite(t *testing.T) {
 	}
 }
 
-// Regression test for C1: rollback on failed writes.
+// A failed write must not leave a half-applied rename in the node tree.
 func TestApplyDraftRollbackOnWriteFailure(t *testing.T) {
 	st := testEditorState(t, editorFixtureYAML)
 	d := newDraft(st.cfg, "webfarm")
@@ -247,7 +247,7 @@ func TestApplyDraftRollbackOnWriteFailure(t *testing.T) {
 	}
 }
 
-// Regression test for I1: collision guard.
+// Renames and added sessions must not collide with an existing name.
 func TestApplyDraftRejectsDuplicateNames(t *testing.T) {
 	st := testEditorState(t, editorFixtureYAML)
 
@@ -281,7 +281,7 @@ func TestApplyDraftRejectsDuplicateNames(t *testing.T) {
 	}
 }
 
-// Regression test for I3: draft mutations don't leak into st.cfg.
+// After a save, the draft and the typed config must not share memory.
 func TestApplyDraftNoAliasAfterSave(t *testing.T) {
 	st := testEditorState(t, editorFixtureYAML)
 	d := newDraft(st.cfg, "webfarm")
@@ -308,7 +308,7 @@ func TestApplyDraftNoAliasAfterSave(t *testing.T) {
 	}
 }
 
-// Regression test for M1: pure rename preserves flow-style and comments.
+// A pure rename keeps the session body's flow style and comments.
 func TestApplyDraftPureRenamePreservesFormat(t *testing.T) {
 	st := testEditorState(t, editorFixtureYAML)
 
diff --git a/internal/tmux/operations.go b/internal/tmux/operations.go
index eb2df6f..f1a3a53 100644
--- a/internal/tmux/operations.go
+++ b/internal/tmux/operations.go
@@ -198,19 +198,6 @@ func (c *Client) SelectWindowByID(windowID string) error {
 	return err
 }
 
-// BaseIndex returns the global base-index option (default 0).
-func (c *Client) BaseIndex() (int, error) {
-	out, err := c.Run("show-options", "-gv", "base-index")
-	if err != nil {
-		return 0, nil
-	}
-	idx, err := strconv.Atoi(strings.TrimSpace(out))
-	if err != nil {
-		return 0, nil
-	}
-	return idx, nil
-}
-
 // SetPaneTitle sets the title of the target pane (visible in tmux's
 // pane-border-format if configured to show #{pane_title}).
 func (c *Client) SetPaneTitle(target, title string) error {
@@ -252,21 +239,6 @@ func (c *Client) SelectLayout(windowTarget, layoutName string) error {
 	return err
 }
 
-// NewWindowInSession creates a new window in the named session and returns
-// the new window's id. The session must already exist. Unlike CreateWindow,
-// the new window is selected (active) immediately.
-func (c *Client) NewWindowInSession(session, name, startDir string) (string, error) {
-	args := []string{"new-window", "-t", "=" + session, "-P", "-F", "#{window_id}", "-n", name}
-	if startDir != "" {
-		args = append(args, "-c", startDir)
-	}
-	out, err := c.Run(args...)
-	if err != nil {
-		return "", err
-	}
-	return strings.TrimSpace(out), nil
-}
-
 // WindowInfo describes a single window for inspection / import.
 type WindowInfo struct {
 	ID     string // tmux window id (@N)