diff --git a/claudetool/codereview/codereview.go b/claudetool/codereview/codereview.go
index 8051bf7..2745957 100644
--- a/claudetool/codereview/codereview.go
+++ b/claudetool/codereview/codereview.go
@@ -17,7 +17,7 @@
 // A CodeReviewer manages quality checks.
 type CodeReviewer struct {
 	repoRoot        string
-	initialCommit   string
+	sketchBaseRef   string
 	initialStatus   []fileStatus // git status of files at initial commit, absolute paths
 	reviewed        []string     // history of all commits which have been reviewed
 	initialWorktree string       // git worktree at initial commit, absolute path
@@ -29,17 +29,17 @@
 	DoLLMReview = true
 )
 
-func NewCodeReviewer(ctx context.Context, repoRoot, initialCommit string, llmReview bool) (*CodeReviewer, error) {
+func NewCodeReviewer(ctx context.Context, repoRoot, sketchBaseRef string, llmReview bool) (*CodeReviewer, error) {
 	r := &CodeReviewer{
 		repoRoot:      repoRoot,
-		initialCommit: initialCommit,
+		sketchBaseRef: sketchBaseRef,
 		llmReview:     llmReview,
 	}
 	if r.repoRoot == "" {
 		return nil, fmt.Errorf("NewCodeReviewer: repoRoot must be non-empty")
 	}
-	if r.initialCommit == "" {
-		return nil, fmt.Errorf("NewCodeReviewer: initialCommit must be non-empty")
+	if r.sketchBaseRef == "" {
+		return nil, fmt.Errorf("NewCodeReviewer: sketchBaseRef must be non-empty")
 	}
 	// Confirm that root is in fact the git repo root.
 	root, err := claudetool.FindRepoRoot(r.repoRoot)
@@ -65,7 +65,7 @@
 // It is best-effort only.
 func (r *CodeReviewer) autoformat(ctx context.Context) []string {
 	// Refuse to format if initial commit is not an ancestor of HEAD
-	err := r.requireHEADDescendantOfInitialCommit(ctx)
+	err := r.requireHEADDescendantOfSketchBaseRef(ctx)
 	if err != nil {
 		slog.WarnContext(ctx, "CodeReviewer.Autoformat refusing to format", "err", err)
 		return nil
@@ -83,7 +83,7 @@
 	}
 	// Retrieve a list of all files changed
 	// TODO: instead of one git diff --name-only and then N --name-status, do one --name-status.
-	changedFiles, err := r.changedFiles(ctx, r.initialCommit, head)
+	changedFiles, err := r.changedFiles(ctx, r.sketchBaseRef, head)
 	if err != nil {
 		slog.WarnContext(ctx, "CodeReviewer.Autoformat unable to get changed files", "err", err)
 		return nil
@@ -252,7 +252,7 @@
 
 // gitFileStatus returns the status of a file (A for added, M for modified, D for deleted, etc.)
 func (r *CodeReviewer) gitFileStatus(ctx context.Context, file string) (string, error) {
-	cmd := exec.CommandContext(ctx, "git", "diff", "--name-status", r.initialCommit, "HEAD", "--", file)
+	cmd := exec.CommandContext(ctx, "git", "diff", "--name-status", r.sketchBaseRef, "HEAD", "--", file)
 	cmd.Dir = r.repoRoot
 	out, err := cmd.CombinedOutput()
 	if err != nil {
@@ -361,7 +361,7 @@
 // ModTidy runs go mod tidy if go module files have changed.
 // Returns a list of files changed by go mod tidy (empty if none).
 func (r *CodeReviewer) ModTidy(ctx context.Context) ([]string, error) {
-	err := r.requireHEADDescendantOfInitialCommit(ctx)
+	err := r.requireHEADDescendantOfSketchBaseRef(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("cannot run ModTidy: %w", err)
 	}
@@ -372,7 +372,7 @@
 		return nil, fmt.Errorf("failed to get current commit: %w", err)
 	}
 
-	changedFiles, err := r.changedFiles(ctx, r.initialCommit, currentCommit)
+	changedFiles, err := r.changedFiles(ctx, r.sketchBaseRef, currentCommit)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get changed files: %w", err)
 	}
diff --git a/claudetool/codereview/differential.go b/claudetool/codereview/differential.go
index 37728d4..f12b4f0 100644
--- a/claudetool/codereview/differential.go
+++ b/claudetool/codereview/differential.go
@@ -64,7 +64,7 @@
 	// This should help avoid the model getting blocked by a broken code review tool.
 	r.reviewed = append(r.reviewed, currentCommit)
 
-	changedFiles, err := r.changedFiles(ctx, r.initialCommit, currentCommit)
+	changedFiles, err := r.changedFiles(ctx, r.sketchBaseRef, currentCommit)
 	if err != nil {
 		slog.DebugContext(ctx, "CodeReviewer.Run: failed to get changed files", "err", err)
 		return nil, err
@@ -154,7 +154,7 @@
 	if err != nil {
 		return err
 	}
-	worktreeCmd := exec.CommandContext(ctx, "git", "worktree", "add", "--detach", tmpDir, r.initialCommit)
+	worktreeCmd := exec.CommandContext(ctx, "git", "worktree", "add", "--detach", tmpDir, r.sketchBaseRef)
 	worktreeCmd.Dir = r.repoRoot
 	out, err := worktreeCmd.CombinedOutput()
 	if err != nil {
@@ -274,7 +274,7 @@
 		}
 
 		// Check if the file exists in the initial commit
-		checkCmd := exec.CommandContext(ctx, "git", "cat-file", "-e", fmt.Sprintf("%s:%s", r.initialCommit, relFile))
+		checkCmd := exec.CommandContext(ctx, "git", "cat-file", "-e", fmt.Sprintf("%s:%s", r.sketchBaseRef, relFile))
 		checkCmd.Dir = r.repoRoot
 		if err := checkCmd.Run(); err == nil {
 			// File exists in initial commit
@@ -491,21 +491,21 @@
 }
 
 func (r *CodeReviewer) IsInitialCommit(commit string) bool {
-	return commit == r.initialCommit
+	return commit == r.sketchBaseRef
 }
 
-// requireHEADDescendantOfInitialCommit returns an error if HEAD is not a descendant of r.initialCommit.
+// requireHEADDescendantOfSketchBaseRef returns an error if HEAD is not a descendant of r.initialCommit.
 // This serves two purposes:
 //   - ensures we're not still on the initial commit
 //   - ensures we're not on a separate branch or upstream somewhere, which would be confusing
-func (r *CodeReviewer) requireHEADDescendantOfInitialCommit(ctx context.Context) error {
+func (r *CodeReviewer) requireHEADDescendantOfSketchBaseRef(ctx context.Context) error {
 	head, err := r.CurrentCommit(ctx)
 	if err != nil {
 		return err
 	}
 
 	// Note: Git's merge-base --is-ancestor checks strict ancestry (i.e., <), so a commit is NOT an ancestor of itself.
-	cmd := exec.CommandContext(ctx, "git", "merge-base", "--is-ancestor", r.initialCommit, head)
+	cmd := exec.CommandContext(ctx, "git", "merge-base", "--is-ancestor", r.sketchBaseRef, head)
 	cmd.Dir = r.repoRoot
 	err = cmd.Run()
 	if err != nil {
@@ -890,7 +890,7 @@
 	}
 
 	buf := new(strings.Builder)
-	fmt.Fprintf(buf, "Test regressions detected between initial commit (%s) and HEAD:\n\n", r.initialCommit)
+	fmt.Fprintf(buf, "Test regressions detected between initial commit (%s) and HEAD:\n\n", r.sketchBaseRef)
 
 	for i, reg := range regressions {
 		fmt.Fprintf(buf, "%d: %v: ", i+1, reg.Source())
diff --git a/claudetool/codereview/llm_review.go b/claudetool/codereview/llm_review.go
index 32a8e00..df8af9b 100644
--- a/claudetool/codereview/llm_review.go
+++ b/claudetool/codereview/llm_review.go
@@ -17,7 +17,7 @@
 // doLLMReview analyzes the diff using an LLM subagent.
 func (r *CodeReviewer) doLLMReview(ctx context.Context) (string, error) {
 	// Get the full diff between initial commit and HEAD
-	cmd := exec.CommandContext(ctx, "git", "diff", r.initialCommit, "HEAD")
+	cmd := exec.CommandContext(ctx, "git", "diff", r.sketchBaseRef, "HEAD")
 	cmd.Dir = r.repoRoot
 	out, err := cmd.CombinedOutput()
 	if err != nil {