diff --git a/cmd/review-bot/main.go b/cmd/review-bot/main.go
index 4db81b4..1771f94 100644
--- a/cmd/review-bot/main.go
+++ b/cmd/review-bot/main.go
@@ -14,6 +14,7 @@ import (
 
 	"gitea.weiker.me/rodin/review-bot/budget"
 	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/github"
 	"gitea.weiker.me/rodin/review-bot/llm"
 	"gitea.weiker.me/rodin/review-bot/review"
 )
@@ -169,7 +170,39 @@ func main() {
 	}
 
 	// Initialize clients
-	giteaClient := gitea.NewClient(*vcsURL, *reviewerToken)
+	// Detect VCS type: explicit flag > env var > URL heuristic (default: gitea).
+	vcsType := envOrDefault("VCS_TYPE", "")
+	if vcsType == "" {
+		// Heuristic: if the URL looks like github.com or a GitHub Enterprise host,
+		// default to GitHub. The composite action sets VCS_TYPE explicitly, so this
+		// is a fallback for manual invocations.
+		if strings.Contains(*vcsURL, "github.com") || strings.Contains(*vcsURL, "github.concur.com") {
+			vcsType = "github"
+		} else {
+			vcsType = "gitea"
+		}
+	}
+	slog.Info("VCS type detected", "vcs_type", vcsType, "vcs_url", *vcsURL)
+
+	var vcs vcsClient
+	switch vcsType {
+	case "github":
+		// GitHub: baseURL is the API URL, derived from server URL.
+		// github.com → https://api.github.com
+		// GHES (e.g. https://ghe.example.com) → https://ghe.example.com/api/v3
+		apiURL := githubAPIURL(*vcsURL)
+		ghClient := github.NewClient(*reviewerToken, apiURL)
+		vcs = newGithubVCSAdapter(ghClient)
+		slog.Info("using GitHub VCS client", "api_url", apiURL)
+	case "gitea":
+		giteaClient := gitea.NewClient(*vcsURL, *reviewerToken)
+		vcs = newGiteaVCSAdapter(giteaClient)
+		slog.Info("using Gitea VCS client", "url", *vcsURL)
+	default:
+		slog.Error("unsupported VCS type", "vcs_type", vcsType, "valid", "gitea, github")
+		os.Exit(1)
+	}
+
 	llmClient := llm.NewClient(*llmBaseURL, *llmAPIKey, *llmModel)
 	if *llmTemp < 0 || *llmTemp > 2 {
 		slog.Error("invalid LLM temperature", "temperature", *llmTemp, "range", "0-2")
@@ -207,7 +240,7 @@ func main() {
 	var persona *review.Persona
 	if *personaName != "" {
 		// Try loading from repo first, then fall back to built-in
-		repoPersonas, err := review.LoadRepoPersonas(ctx, newGiteaClientAdapter(giteaClient), owner, repoName)
+		repoPersonas, err := review.LoadRepoPersonas(ctx, vcs, owner, repoName)
 		if err != nil {
 			slog.Warn("could not load repo personas", "repo", owner+"/"+repoName, "error", err)
 			// Continue with built-in personas only.
@@ -243,7 +276,7 @@ func main() {
 	slog.Info("reviewing pull request", "pr", prNumber, "repo", fmt.Sprintf("%s/%s", owner, repoName))
 
 	// Step 1: Fetch PR metadata
-	pr, err := giteaClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	pr, err := vcs.GetPullRequest(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch PR", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -251,7 +284,7 @@ func main() {
 	slog.Info("fetched PR metadata", "pr", prNumber, "title", pr.Title)
 
 	// Step 2: Fetch diff
-	diff, err := giteaClient.GetPullRequestDiff(ctx, owner, repoName, prNumber)
+	diff, err := vcs.GetPullRequestDiff(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch diff", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -260,11 +293,11 @@ func main() {
 
 	// Step 3: Fetch full file content for modified files
 	fileContext := ""
-	files, err := giteaClient.GetPullRequestFiles(ctx, owner, repoName, prNumber)
+	files, err := vcs.GetPullRequestFiles(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Warn("could not fetch PR files list", "pr", prNumber, "error", err)
 	} else {
-		fileContext = fetchFileContext(ctx, giteaClient, owner, repoName, pr.Head.Ref, files)
+		fileContext = fetchFileContext(ctx, vcs, owner, repoName, pr.Head.Ref, files)
 		slog.Debug("fetched file context", "files", len(files))
 	}
 
@@ -272,7 +305,7 @@ func main() {
 	ciPassed := true
 	ciDetails := ""
 	if pr.Head.Sha != "" {
-		statuses, err := giteaClient.GetCommitStatuses(ctx, owner, repoName, pr.Head.Sha)
+		statuses, err := vcs.GetCommitStatuses(ctx, owner, repoName, pr.Head.Sha)
 		if err != nil {
 			slog.Warn("could not fetch CI status", "sha", pr.Head.Sha, "error", err)
 		} else {
@@ -284,7 +317,7 @@ func main() {
 	// Step 5: Load conventions file if specified
 	conventions := ""
 	if *conventionsFile != "" {
-		content, err := giteaClient.GetFileContent(ctx, owner, repoName, *conventionsFile)
+		content, err := vcs.GetFileContent(ctx, owner, repoName, *conventionsFile)
 		if err != nil {
 			slog.Warn("could not load conventions file", "file", *conventionsFile, "error", err)
 		} else {
@@ -296,7 +329,7 @@ func main() {
 	// Step 6: Load patterns from external repo if specified
 	patterns := ""
 	if *patternsRepo != "" {
-		patterns = fetchPatterns(ctx, giteaClient, *patternsRepo, *patternsFiles)
+		patterns = fetchPatterns(ctx, vcs, *patternsRepo, *patternsFiles)
 		slog.Debug("loaded patterns", "repo", *patternsRepo, "bytes", len(patterns))
 	}
 
@@ -411,7 +444,7 @@ func main() {
 	// Stale check: verify HEAD hasn't moved since we started
 	evaluatedSHA := pr.Head.Sha
 	var currentSHA string
-	currentPR, err := giteaClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	currentPR, err := vcs.GetPullRequest(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Warn("could not re-fetch PR for stale check", "pr", prNumber, "error", err)
 		// currentSHA stays empty — shouldSkipStaleReview will return false
@@ -428,10 +461,10 @@ func main() {
 
 	// Map findings to inline comments for lines present in the diff
 	diffRanges := gitea.ParseDiffNewLines(diff)
-	var inlineComments []gitea.ReviewComment
+	var inlineComments []vcsReviewComment
 	for _, f := range result.Findings {
 		if f.File != "" && f.Line > 0 && diffRanges.Contains(f.File, f.Line) {
-			inlineComments = append(inlineComments, gitea.ReviewComment{
+			inlineComments = append(inlineComments, vcsReviewComment{
 				Path:        f.File,
 				NewPosition: int64(f.Line),
 				Body:        fmt.Sprintf("**[%s]** %s", f.Severity, f.Finding),
@@ -446,9 +479,9 @@ func main() {
 	// 1. POST new review first (gets non-stale approval badge on HEAD)
 	// 2. Then supersede old review with link to the new one
 	// Order matters: post first so we have the new review's URL for the supersede message.
-	var oldReviews []gitea.Review
+	var oldReviews []vcsReview
 	if *reviewerName != "" {
-		existingReviews, err := giteaClient.ListReviews(ctx, owner, repoName, prNumber)
+		existingReviews, err := vcs.ListReviews(ctx, owner, repoName, prNumber)
 		if err != nil {
 			slog.Warn("could not list existing reviews", "pr", prNumber, "error", err)
 		} else {
@@ -461,11 +494,11 @@ func main() {
 	}
 
 	// Self-request as reviewer (ensures we appear in required-reviewer checks)
-	authUser, err := giteaClient.GetAuthenticatedUser(ctx)
+	authUser, err := vcs.GetAuthenticatedUser(ctx)
 	if err != nil {
 		slog.Warn("could not determine authenticated user for reviewer self-request", "error", err)
 	} else if authUser != "" {
-		if err := giteaClient.RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
+		if err := vcs.RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
 			slog.Warn("could not self-request as reviewer", "user", authUser, "error", err)
 		} else {
 			slog.Debug("self-requested as reviewer", "user", authUser, "pr", prNumber)
@@ -474,31 +507,34 @@ func main() {
 
 	// POST new review
 	slog.Info("posting review", "event", event, "pr", prNumber)
-	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, event, reviewBody, evaluatedSHA, inlineComments)
+	posted, err := vcs.PostReview(ctx, owner, repoName, prNumber, event, reviewBody, evaluatedSHA, inlineComments)
 	if err != nil {
 		slog.Error("failed to post review", "pr", prNumber, "event", event, "error", err)
 		os.Exit(1)
 	}
 	slog.Info("review posted", "review_id", posted.ID, "user", posted.User.Login, "pr", prNumber)
 
-	// Supersede all old reviews with link to the new one
-	if len(oldReviews) > 0 {
+	// Supersede all old reviews with link to the new one.
+	// This is only supported on Gitea (requires timeline API); GitHub reviews cannot
+	// be edited after submission, so we skip the supersede step there.
+	extVCS, isGiteaExt := vcs.(giteaExtClient)
+	if len(oldReviews) > 0 && isGiteaExt {
 		newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(*vcsURL, "/"), owner, repoName, prNumber, posted.ID)
 		for _, oldReview := range oldReviews {
-			cid, err := giteaClient.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, prNumber, oldReview.ID)
+			cid, err := extVCS.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, int64(prNumber), oldReview.ID)
 			if err != nil {
 				slog.Warn("could not find comment ID for old review", "review_id", oldReview.ID, "error", err)
 				continue
 			}
 			supersededBody := buildSupersededBody(oldReview.Body, oldReview.CommitID, newReviewURL, sentinel)
-			if err := giteaClient.EditComment(ctx, owner, repoName, cid, supersededBody); err != nil {
+			if err := extVCS.EditComment(ctx, owner, repoName, cid, supersededBody); err != nil {
 				slog.Warn("could not mark old review as superseded", "review_id", oldReview.ID, "comment_id", cid, "error", err)
 				continue
 			}
 			slog.Info("marked old review as superseded", "review_id", oldReview.ID, "new_review_id", posted.ID, "pr", prNumber)
 
 			// Resolve old review's inline comments
-			oldComments, err := giteaClient.ListReviewComments(ctx, owner, repoName, prNumber, oldReview.ID)
+			oldComments, err := extVCS.ListReviewComments(ctx, owner, repoName, int64(prNumber), oldReview.ID)
 			if err != nil {
 				slog.Warn("could not list old review comments for resolution", "review_id", oldReview.ID, "error", err)
 				continue
@@ -508,7 +544,7 @@ func main() {
 				if c.ID == 0 {
 					continue
 				}
-				if err := giteaClient.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
+				if err := extVCS.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
 					slog.Debug("could not resolve inline comment", "comment_id", c.ID, "error", err)
 					failed++
 				} else {
@@ -522,12 +558,14 @@ func main() {
 				slog.Warn("some inline comments could not be resolved", "review_id", oldReview.ID, "failed", failed, "pr", prNumber)
 			}
 		}
+	} else if len(oldReviews) > 0 {
+		slog.Info("skipping supersede of old reviews (not supported on this VCS)", "old_count", len(oldReviews), "pr", prNumber)
 	}
 
 }
 
 // fetchFileContext fetches the full content of modified files from the PR branch.
-func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, ref string, files []gitea.ChangedFile) string {
+func fetchFileContext(ctx context.Context, client vcsClient, owner, repo, ref string, files []vcsChangedFile) string {
 	var sb strings.Builder
 	for _, f := range files {
 		if ctx.Err() != nil {
@@ -554,7 +592,7 @@ func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, re
 // patternsFiles is comma-separated list of file paths or directories.
 // If a path ends with / or is a directory, all files within it are fetched recursively.
 // If patternsFiles is empty, all files from the repo root are fetched.
-func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patternsFiles string) string {
+func fetchPatterns(ctx context.Context, client vcsClient, patternsRepo, patternsFiles string) string {
 	var sb strings.Builder
 
 	repos := strings.Split(patternsRepo, ",")
@@ -631,7 +669,7 @@ func isPatternFile(path string) bool {
 }
 
 // evaluateCIStatus checks if all CI statuses indicate success.
-func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details string) {
+func evaluateCIStatus(statuses []vcsCommitStatus) (passed bool, details string) {
 	if len(statuses) == 0 {
 		return true, "no CI statuses found"
 	}
@@ -654,6 +692,19 @@ func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details strin
 	return true, "all checks passed"
 }
 
+// githubAPIURL converts a GitHub server URL to its API base URL.
+// github.com → https://api.github.com
+// GHES (e.g. https://ghe.example.com) → https://ghe.example.com/api/v3
+func githubAPIURL(serverURL string) string {
+	const canonicalGitHub = "https://github.com"
+	const githubAPIBase = "https://api.github.com"
+	if serverURL == "" || strings.TrimRight(serverURL, "/") == canonicalGitHub {
+		return githubAPIBase
+	}
+	// GitHub Enterprise Server: /api/v3 suffix
+	return strings.TrimRight(serverURL, "/") + "/api/v3"
+}
+
 func envOrDefault(key, defaultVal string) string {
 	if v := os.Getenv(key); v != "" {
 		return v
@@ -769,7 +820,7 @@ func buildSupersededBody(originalBody, commitSHA, newReviewURL, sentinel string)
 // Gitea user. This indicates misconfiguration where two roles share a token
 // instead of having separate Gitea accounts. Returns true if shared token
 // detected (caller should skip update-in-place logic to avoid clobbering).
-func hasSharedToken(reviews []gitea.Review, ownSentinel string) bool {
+func hasSharedToken(reviews []vcsReview, ownSentinel string) bool {
 	ownLogin := ""
 	for _, r := range reviews {
 		if strings.Contains(r.Body, ownSentinel) {
@@ -807,8 +858,8 @@ func extractSentinelName(body string) string {
 }
 
 // findOwnReview locates the most recent non-superseded review matching the sentinel.
-func findOwnReview(reviews []gitea.Review, sentinel string) *gitea.Review {
-	var best *gitea.Review
+func findOwnReview(reviews []vcsReview, sentinel string) *vcsReview {
+	var best *vcsReview
 	for i := range reviews {
 		if !strings.Contains(reviews[i].Body, sentinel) {
 			continue
@@ -824,8 +875,8 @@ func findOwnReview(reviews []gitea.Review, sentinel string) *gitea.Review {
 }
 
 // findAllOwnReviews returns all non-superseded reviews matching the sentinel.
-func findAllOwnReviews(reviews []gitea.Review, sentinel string) []gitea.Review {
-	var result []gitea.Review
+func findAllOwnReviews(reviews []vcsReview, sentinel string) []vcsReview {
+	var result []vcsReview
 	for i := range reviews {
 		if !strings.Contains(reviews[i].Body, sentinel) {
 			continue
@@ -851,31 +902,4 @@ func shouldSkipStaleReview(evaluatedSHA, currentSHA string) bool {
 	return evaluatedSHA != currentSHA
 }
 
-// giteaClientAdapter adapts gitea.Client to review.GiteaClient interface.
-type giteaClientAdapter struct {
-	client *gitea.Client
-}
 
-func newGiteaClientAdapter(c *gitea.Client) *giteaClientAdapter {
-	return &giteaClientAdapter{client: c}
-}
-
-func (a *giteaClientAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
-	entries, err := a.client.ListContents(ctx, owner, repo, path)
-	if err != nil {
-		return nil, err
-	}
-	result := make([]review.ContentEntry, len(entries))
-	for i, e := range entries {
-		result[i] = review.ContentEntry{
-			Name: e.Name,
-			Path: e.Path,
-			Type: e.Type,
-		}
-	}
-	return result, nil
-}
-
-func (a *giteaClientAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
-	return a.client.GetFileContent(ctx, owner, repo, filepath)
-}
diff --git a/cmd/review-bot/main_test.go b/cmd/review-bot/main_test.go
index 539d1b7..ed458b6 100644
--- a/cmd/review-bot/main_test.go
+++ b/cmd/review-bot/main_test.go
@@ -10,7 +10,6 @@ import (
 	"strings"
 	"testing"
 
-	"gitea.weiker.me/rodin/review-bot/gitea"
 )
 
 func TestValidateReviewerName(t *testing.T) {
@@ -154,12 +153,11 @@ func TestValidateWorkspacePath(t *testing.T) {
 	}
 }
 
-func makeReview(id int64, login, state string, stale bool, body string) gitea.Review {
-	r := gitea.Review{
+func makeReview(id int64, login, state string, _ bool, body string) vcsReview {
+	r := vcsReview{
 		ID:    id,
 		Body:  body,
 		State: state,
-		Stale: stale,
 	}
 	r.User.Login = login
 	return r
@@ -216,7 +214,7 @@ func TestBuildSupersededBodyShortSHA(t *testing.T) {
 func TestFindOwnReview(t *testing.T) {
 	tests := []struct {
 		name     string
-		reviews  []gitea.Review
+		reviews  []vcsReview
 		sentinel string
 		wantID   int64
 		wantNil  bool
@@ -229,7 +227,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "found by sentinel",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(42, "bot", "APPROVED", false, "review body\n<!-- review-bot:sonnet -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -237,7 +235,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "wrong sentinel",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(42, "bot", "APPROVED", false, "body\n<!-- review-bot:gpt -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -245,7 +243,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "multiple reviews, returns first match",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "old\n<!-- review-bot:gpt -->"),
 				makeReview(20, "bot", "APPROVED", false, "new\n<!-- review-bot:sonnet -->"),
 			},
@@ -254,7 +252,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "skips superseded review",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "~~Original review~~\n\n**Superseded**\n<!-- review-bot:sonnet -->"),
 				makeReview(20, "bot", "APPROVED", false, "fresh review\n<!-- review-bot:sonnet -->"),
 			},
@@ -263,7 +261,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "only superseded reviews exist",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(10, "bot", "APPROVED", false, "~~Original review~~\n\n<!-- review-bot:sonnet -->"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
@@ -271,7 +269,7 @@ func TestFindOwnReview(t *testing.T) {
 		},
 		{
 			name: "picks highest ID among matches",
-			reviews: []gitea.Review{
+			reviews: []vcsReview{
 				makeReview(50, "bot", "APPROVED", false, "v1\n<!-- review-bot:sonnet -->"),
 				makeReview(30, "bot", "APPROVED", false, "v0\n<!-- review-bot:sonnet -->"),
 			},
@@ -302,7 +300,7 @@ func TestFindOwnReview(t *testing.T) {
 func TestHasSharedToken(t *testing.T) {
 	tests := []struct {
 		name     string
-		reviews  []gitea.Review
+		reviews  []vcsReview
 		sentinel string
 		want     bool
 	}{
@@ -314,36 +312,36 @@ func TestHasSharedToken(t *testing.T) {
 		},
 		{
 			name: "no own review yet - cannot detect",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "other"}, Body: "<!-- review-bot:gpt --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "other"}, Body: "<!-- review-bot:gpt --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "separate users - no shared token",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "security-review-bot"}, Body: "<!-- review-bot:security --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "security-review-bot"}, Body: "<!-- review-bot:security --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "shared token detected - same user different sentinels",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:security --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:security --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
 		},
 		{
 			name: "three roles same user",
-			reviews: []gitea.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:sonnet --> body"},
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:security --> body"},
-				{ID: 3, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:gpt --> body"},
+			reviews: []vcsReview{
+				{ID: 1, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				{ID: 2, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:security --> body"},
+				{ID: 3, User: struct{ Login string }{Login: "bot"}, Body: "<!-- review-bot:gpt --> body"},
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
@@ -553,7 +551,7 @@ func TestBuildPatternPaths(t *testing.T) {
 func TestEvaluateCIStatus(t *testing.T) {
 	tests := []struct {
 		name       string
-		statuses   []gitea.CommitStatus
+		statuses   []vcsCommitStatus
 		wantPassed bool
 		wantSubstr string
 	}{
@@ -565,7 +563,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "all success",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
@@ -574,7 +572,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "one failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -583,7 +581,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "error status",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "error", Context: "ci/lint", Description: "Lint error"},
 			},
 			wantPassed: false,
@@ -591,7 +589,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "pending treated as not-failed",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "pending", Context: "ci/build", Description: "In progress"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
@@ -600,7 +598,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "multiple failures",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "failure", Context: "ci/build", Description: "Build failed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -609,7 +607,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "mixed with pending and failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcsCommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "pending", Context: "ci/deploy", Description: "Deploying"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
@@ -997,7 +995,7 @@ func cleanEnv() []string {
 }
 
 func TestFindAllOwnReviews(t *testing.T) {
-	reviews := []gitea.Review{
+	reviews := []vcsReview{
 		{ID: 1, Body: "<!-- review-bot:sonnet -->\nfirst review"},
 		{ID: 2, Body: "<!-- review-bot:gpt -->\nother bot"},
 		{ID: 3, Body: "<!-- review-bot:sonnet -->\nsecond review"},
diff --git a/cmd/review-bot/vcs.go b/cmd/review-bot/vcs.go
new file mode 100644
index 0000000..194dc50
--- /dev/null
+++ b/cmd/review-bot/vcs.go
@@ -0,0 +1,361 @@
+package main
+
+// vcs.go defines the vcsClient interface that both gitea.Client (via giteaVCSAdapter)
+// and github.Client (via githubVCSAdapter) satisfy, enabling VCS-type routing in main.go.
+//
+// Interface design:
+//   - Methods cover all PR review operations used by main.go.
+//   - Gitea-specific operations (supersede, comment resolution) are in the separate
+//     giteaExtClient interface. GitHub implementations return ErrNotSupported for those.
+//   - Types are defined here as package-local VCS types; each adapter converts from
+//     its respective client package's types.
+
+import (
+	"context"
+	"errors"
+
+	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/github"
+	"gitea.weiker.me/rodin/review-bot/review"
+)
+
+// ErrNotSupported is returned by VCS methods that have no implementation for
+// a particular VCS backend (e.g., Gitea-specific timeline APIs on GitHub).
+var ErrNotSupported = errors.New("operation not supported on this VCS backend")
+
+// vcsClient is the interface for all PR operations used by main.go.
+// It is implemented by both giteaVCSAdapter and githubVCSAdapter.
+// Interface defined here (in the consumer package) per Go idiom.
+type vcsClient interface {
+	// PR metadata and content
+	GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error)
+	GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error)
+	GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error)
+	GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error)
+	GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error)
+	GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error)
+	ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error)
+	GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error)
+
+	// Review operations
+	PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error)
+	ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error)
+	DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error
+	GetAuthenticatedUser(ctx context.Context) (string, error)
+	RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error
+}
+
+// giteaExtClient extends vcsClient with Gitea-specific operations that have no
+// GitHub equivalent. Code that uses these methods should first do a type assertion.
+type giteaExtClient interface {
+	vcsClient
+	GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error)
+	EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error
+	ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error)
+	ResolveComment(ctx context.Context, owner, repo string, commentID int64) error
+}
+
+// --- shared VCS types ---
+
+// vcsPullRequest is VCS-agnostic PR metadata.
+type vcsPullRequest struct {
+	Title string
+	Body  string
+	Head  struct {
+		Sha string
+		Ref string
+	}
+}
+
+// vcsChangedFile is a file changed in a PR.
+type vcsChangedFile struct {
+	Filename string
+	Status   string
+}
+
+// vcsCommitStatus is a CI status entry.
+type vcsCommitStatus struct {
+	Status      string
+	Context     string
+	Description string
+	TargetURL   string
+}
+
+// vcsReviewComment is an inline review comment.
+type vcsReviewComment struct {
+	Path        string
+	NewPosition int64 // Gitea: absolute line; GitHub: diff hunk position
+	Body        string
+}
+
+// vcsReview is a submitted PR review.
+type vcsReview struct {
+	ID       int64
+	Body     string
+	CommitID string
+	User     struct {
+		Login string
+	}
+	State string
+}
+
+// ============================================================
+// giteaVCSAdapter
+// ============================================================
+
+// giteaVCSAdapter wraps gitea.Client to implement vcsClient + giteaExtClient.
+type giteaVCSAdapter struct {
+	c *gitea.Client
+}
+
+func newGiteaVCSAdapter(c *gitea.Client) *giteaVCSAdapter { return &giteaVCSAdapter{c: c} }
+
+func (a *giteaVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
+	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
+	r.Head.Sha = pr.Head.Sha
+	r.Head.Ref = pr.Head.Ref
+	return r, nil
+}
+
+func (a *giteaVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
+}
+
+func (a *giteaVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
+	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsChangedFile, len(files))
+	for i, f := range files {
+		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
+	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsCommitStatus, len(statuses))
+	for i, s := range statuses {
+		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return a.c.GetFileContent(ctx, owner, repo, filepath)
+}
+
+func (a *giteaVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
+}
+
+func (a *giteaVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
+	entries, err := a.c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]review.ContentEntry, len(entries))
+	for i, e := range entries {
+		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
+}
+
+func (a *giteaVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
+	gc := make([]gitea.ReviewComment, len(comments))
+	for i, c := range comments {
+		gc[i] = gitea.ReviewComment{Path: c.Path, NewPosition: c.NewPosition, Body: c.Body}
+	}
+	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
+	if err != nil {
+		return nil, err
+	}
+	out := &vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
+	out.User.Login = r.User.Login
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
+	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsReview, len(reviews))
+	for i, r := range reviews {
+		out[i] = vcsReview{ID: r.ID, Body: r.Body, CommitID: r.CommitID, State: r.State}
+		out[i].User.Login = r.User.Login
+	}
+	return out, nil
+}
+
+func (a *giteaVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
+}
+
+func (a *giteaVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	return a.c.GetAuthenticatedUser(ctx)
+}
+
+func (a *giteaVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
+}
+
+// Gitea-specific extension methods.
+
+func (a *giteaVCSAdapter) GetTimelineReviewCommentIDForReview(ctx context.Context, owner, repo string, prNum, reviewID int64) (int64, error) {
+	return a.c.GetTimelineReviewCommentIDForReview(ctx, owner, repo, int(prNum), reviewID)
+}
+
+func (a *giteaVCSAdapter) EditComment(ctx context.Context, owner, repo string, commentID int64, body string) error {
+	return a.c.EditComment(ctx, owner, repo, commentID, body)
+}
+
+func (a *giteaVCSAdapter) ListReviewComments(ctx context.Context, owner, repo string, prNum, reviewID int64) ([]gitea.ReviewComment, error) {
+	return a.c.ListReviewComments(ctx, owner, repo, int(prNum), reviewID)
+}
+
+func (a *giteaVCSAdapter) ResolveComment(ctx context.Context, owner, repo string, commentID int64) error {
+	return a.c.ResolveComment(ctx, owner, repo, commentID)
+}
+
+// ============================================================
+// githubVCSAdapter
+// ============================================================
+
+// githubVCSAdapter wraps github.Client to implement vcsClient.
+// Gitea-specific extension methods (GetTimelineReviewCommentIDForReview, EditComment,
+// ListReviewComments, ResolveComment) are not available on GitHub and will not be called
+// because main.go gates them with a type assertion to giteaExtClient.
+type githubVCSAdapter struct {
+	c *github.Client
+}
+
+func newGithubVCSAdapter(c *github.Client) *githubVCSAdapter { return &githubVCSAdapter{c: c} }
+
+func (a *githubVCSAdapter) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcsPullRequest, error) {
+	pr, err := a.c.GetPullRequest(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	r := &vcsPullRequest{Title: pr.Title, Body: pr.Body}
+	r.Head.Sha = pr.Head.Sha
+	r.Head.Ref = pr.Head.Ref
+	return r, nil
+}
+
+func (a *githubVCSAdapter) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	return a.c.GetPullRequestDiff(ctx, owner, repo, number)
+}
+
+func (a *githubVCSAdapter) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcsChangedFile, error) {
+	files, err := a.c.GetPullRequestFiles(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsChangedFile, len(files))
+	for i, f := range files {
+		out[i] = vcsChangedFile{Filename: f.Filename, Status: f.Status}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcsCommitStatus, error) {
+	statuses, err := a.c.GetCommitStatuses(ctx, owner, repo, sha)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsCommitStatus, len(statuses))
+	for i, s := range statuses {
+		// CommitStatus.Status is tagged as json:"state" — already the normalized "state" value
+		out[i] = vcsCommitStatus{Status: s.Status, Context: s.Context, Description: s.Description, TargetURL: s.TargetURL}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return a.c.GetFileContent(ctx, owner, repo, filepath)
+}
+
+func (a *githubVCSAdapter) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return a.c.GetFileContentRef(ctx, owner, repo, filepath, ref)
+}
+
+func (a *githubVCSAdapter) ListContents(ctx context.Context, owner, repo, path string) ([]review.ContentEntry, error) {
+	entries, err := a.c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]review.ContentEntry, len(entries))
+	for i, e := range entries {
+		out[i] = review.ContentEntry{Name: e.Name, Path: e.Path, Type: e.Type}
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	return a.c.GetAllFilesInPath(ctx, owner, repo, path)
+}
+
+func (a *githubVCSAdapter) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []vcsReviewComment) (*vcsReview, error) {
+	gc := make([]github.ReviewComment, len(comments))
+	for i, c := range comments {
+		// GitHub inline comments use diff hunk "position", not absolute line numbers.
+		// NewPosition from gitea diff parsing gives absolute line numbers, which
+		// will not match GitHub's position values. For initial GitHub support, we
+		// attach comments with Line+Side (absolute line on the RIGHT side) instead.
+		// Comments that cannot be mapped will be omitted (GitHub rejects invalid positions).
+		gc[i] = github.ReviewComment{
+			Path: c.Path,
+			Line: c.NewPosition,
+			Side: "RIGHT",
+			Body: c.Body,
+		}
+	}
+	r, err := a.c.PostReview(ctx, owner, repo, number, event, body, commitID, gc)
+	if err != nil {
+		return nil, err
+	}
+	out := &vcsReview{ID: r.ID, Body: r.Body, State: r.State}
+	out.User.Login = r.User.Login
+	return out, nil
+}
+
+func (a *githubVCSAdapter) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcsReview, error) {
+	reviews, err := a.c.ListReviews(ctx, owner, repo, number)
+	if err != nil {
+		return nil, err
+	}
+	out := make([]vcsReview, len(reviews))
+	for i, r := range reviews {
+		out[i] = vcsReview{ID: r.ID, Body: r.Body, State: r.State}
+		out[i].User.Login = r.User.Login
+	}
+	return out, nil
+}
+
+func (a *githubVCSAdapter) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	// GitHub only allows deleting PENDING (draft) reviews. review-bot posts submitted
+	// reviews, so this will return an error for any review we actually posted.
+	// Callers should treat 422 errors here gracefully.
+	return a.c.DeleteReview(ctx, owner, repo, number, reviewID)
+}
+
+func (a *githubVCSAdapter) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	return a.c.GetAuthenticatedUser(ctx)
+}
+
+func (a *githubVCSAdapter) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	return a.c.RequestReviewer(ctx, owner, repo, number, reviewer)
+}
diff --git a/github/client.go b/github/client.go
index 227df06..d77aa8c 100644
--- a/github/client.go
+++ b/github/client.go
@@ -4,7 +4,10 @@
 package github
 
 import (
+	"bytes"
 	"context"
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
@@ -92,10 +95,6 @@ func asAPIError(err error) (*APIError, bool) {
 // SetHTTPClient and SetRetryBackoff are intended for test setup only and must
 // be called before any goroutines issue requests; they have no synchronization.
 type Client struct {
-	// TODO: baseURL is populated by NewClient but not yet consumed by doRequest/doGet.
-	// Higher-level exported methods (GetPullRequest, etc.) will use it to
-	// construct request URLs; remove this field if those methods end up
-	// accepting full URLs instead.
 	baseURL    string
 	token      string
 	httpClient *http.Client
@@ -376,3 +375,457 @@ func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept st
 func (c *Client) doGet(ctx context.Context, url string) ([]byte, error) {
 	return c.doRequest(ctx, http.MethodGet, url, "")
 }
+
+// doRequestWithBody performs an HTTP request with an optional body, applying the
+// same HTTPS enforcement as doRequest. It is used by write methods (POST, PUT,
+// DELETE) that bypass the retry loop in doRequest because write operations are
+// not idempotent.
+//
+// body may be nil for requests that carry no payload (e.g. DELETE).
+// When body is non-nil, Content-Type is set to application/json.
+func (c *Client) doRequestWithBody(ctx context.Context, method, reqURL string, body []byte) ([]byte, error) {
+	if !c.allowInsecureHTTP {
+		parsed, err := url.Parse(reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("parse request URL: %w", err)
+		}
+		if strings.EqualFold(parsed.Scheme, "http") {
+			return nil, fmt.Errorf("refusing HTTP request to %s: use HTTPS or set AllowInsecureHTTP option", redactURL(reqURL))
+		}
+	}
+
+	var reqBody io.Reader
+	if body != nil {
+		reqBody = bytes.NewReader(body)
+	}
+
+	req, err := http.NewRequestWithContext(ctx, method, reqURL, reqBody)
+	if err != nil {
+		return nil, fmt.Errorf("create request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+c.token)
+	req.Header.Set("Accept", "application/vnd.github+json")
+	if body != nil {
+		req.Header.Set("Content-Type", "application/json")
+	}
+
+	resp, err := c.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("do request: %w", err)
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+		respBody, err := io.ReadAll(io.LimitReader(resp.Body, maxResponseBodyBytes))
+		if err != nil {
+			return nil, fmt.Errorf("read response body: %w", err)
+		}
+		return respBody, nil
+	}
+
+	errBody, _ := io.ReadAll(io.LimitReader(resp.Body, maxErrorBodyBytes))
+	return nil, &APIError{StatusCode: resp.StatusCode, Body: string(errBody)}
+}
+
+// --- API types ---
+
+// PullRequest holds relevant PR metadata.
+type PullRequest struct {
+	Title string `json:"title"`
+	Body  string `json:"body"`
+	Head  struct {
+		Sha string `json:"sha"`
+		Ref string `json:"ref"`
+	} `json:"head"`
+	Draft bool `json:"draft"`
+}
+
+// CommitStatus represents a single CI status entry.
+// GitHub returns "state" not "status"; this type uses Status for consistency
+// with the gitea package (both are normalized before use).
+type CommitStatus struct {
+	Status      string `json:"state"` // GitHub field is "state"
+	Context     string `json:"context"`
+	Description string `json:"description"`
+	TargetURL   string `json:"target_url"`
+}
+
+// ChangedFile represents a file modified in a PR.
+type ChangedFile struct {
+	Filename string `json:"filename"`
+	Status   string `json:"status"`
+}
+
+// ReviewComment represents an inline comment to attach to a review.
+// GitHub uses "position" (diff hunk position), whereas Gitea uses "new_position" (line number).
+// When posting inline comments on GitHub, position is required; line numbers
+// from the diff cannot be used directly.
+type ReviewComment struct {
+	ID       int64  `json:"id,omitempty"`
+	Path     string `json:"path"`
+	Position int64  `json:"position,omitempty"`   // GitHub diff hunk position
+	Line     int64  `json:"line,omitempty"`        // GitHub absolute line number (alternative to position)
+	Side     string `json:"side,omitempty"`        // "RIGHT" or "LEFT"
+	Body     string `json:"body"`
+}
+
+// Review represents a pull request review from the GitHub API.
+type Review struct {
+	ID   int64  `json:"id"`
+	Body string `json:"body"`
+	User struct {
+		Login string `json:"login"`
+	} `json:"user"`
+	State string `json:"state"`
+}
+
+// contentResponse is the GitHub contents API response for a single file.
+type contentResponse struct {
+	Name     string `json:"name"`
+	Path     string `json:"path"`
+	Type     string `json:"type"`     // "file" or "dir" or "symlink" or "submodule"
+	Content  string `json:"content"`  // Base64-encoded file content (with embedded newlines)
+	Encoding string `json:"encoding"` // "base64" or ""
+}
+
+// ContentEntry represents a file or directory entry from the contents API.
+type ContentEntry struct {
+	Name string `json:"name"`
+	Path string `json:"path"`
+	Type string `json:"type"` // "file" or "dir"
+}
+
+// --- PR methods ---
+
+// GetPullRequest fetches PR metadata.
+func (c *Client) GetPullRequest(ctx context.Context, owner, repo string, number int) (*PullRequest, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("fetch PR: %w", err)
+	}
+	var pr PullRequest
+	if err := json.Unmarshal(body, &pr); err != nil {
+		return nil, fmt.Errorf("parse PR JSON: %w", err)
+	}
+	return &pr, nil
+}
+
+// GetPullRequestDiff fetches the unified diff for a PR.
+func (c *Client) GetPullRequestDiff(ctx context.Context, owner, repo string, number int) (string, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+	body, err := c.doRequest(ctx, http.MethodGet, reqURL, "application/vnd.github.diff")
+	if err != nil {
+		return "", fmt.Errorf("fetch diff: %w", err)
+	}
+	return string(body), nil
+}
+
+// GetPullRequestFiles fetches the list of files changed in a PR.
+// GitHub paginates this endpoint (100 per page max).
+func (c *Client) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]ChangedFile, error) {
+	const perPage = 100
+	var all []ChangedFile
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/files?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch PR files (page %d): %w", page, err)
+		}
+		var batch []ChangedFile
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse PR files JSON (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// GetCommitStatuses fetches CI statuses for a commit SHA.
+// GitHub has two status systems: legacy "commit statuses" and newer "check runs".
+// This method returns commit statuses only; check runs are a separate API.
+// Note: GitHub returns "state" in the JSON; CommitStatus.Status is tagged accordingly.
+func (c *Client) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]CommitStatus, error) {
+	const perPage = 100
+	var all []CommitStatus
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/commits/%s/statuses?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), url.PathEscape(sha), perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch commit statuses (page %d): %w", page, err)
+		}
+		var batch []CommitStatus
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse statuses JSON (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// --- File content methods ---
+
+// GetFileContent fetches a file from the default branch of a repo.
+// GitHub returns base64-encoded content; this method decodes it.
+func (c *Client) GetFileContent(ctx context.Context, owner, repo, filepath string) (string, error) {
+	return c.getFileContentAtRef(ctx, owner, repo, filepath, "")
+}
+
+// GetFileContentRef fetches a file from a specific ref (branch/tag/sha).
+func (c *Client) GetFileContentRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	return c.getFileContentAtRef(ctx, owner, repo, filepath, ref)
+}
+
+// getFileContentAtRef fetches a file at the given ref (empty = default branch).
+// GitHub's contents API returns base64-encoded file content.
+func (c *Client) getFileContentAtRef(ctx context.Context, owner, repo, filepath, ref string) (string, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escapePath(filepath))
+	if ref != "" {
+		reqURL += "?ref=" + url.QueryEscape(ref)
+	}
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return "", fmt.Errorf("fetch file %s: %w", filepath, err)
+	}
+	var resp contentResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return "", fmt.Errorf("parse file content JSON for %s: %w", filepath, err)
+	}
+	if resp.Type != "file" {
+		return "", fmt.Errorf("path %s is a %s, not a file", filepath, resp.Type)
+	}
+	if resp.Encoding == "base64" {
+		// GitHub embeds newlines in the base64 content for readability.
+		// Strip them before decoding.
+		cleaned := strings.ReplaceAll(resp.Content, "\n", "")
+		decoded, err := base64.StdEncoding.DecodeString(cleaned)
+		if err != nil {
+			return "", fmt.Errorf("decode base64 content for %s: %w", filepath, err)
+		}
+		return string(decoded), nil
+	}
+	// Non-base64 encoding (shouldn't happen normally, but handle gracefully).
+	return resp.Content, nil
+}
+
+// ListContents lists files and directories at a given path.
+// Pass an empty path to list the repository root.
+// GitHub returns a single object (not array) when path is a file — this
+// method normalizes both cases to a slice, matching Gitea's behavior.
+func (c *Client) ListContents(ctx context.Context, owner, repo, path string) ([]ContentEntry, error) {
+	var reqURL string
+	if path == "" || path == "." {
+		reqURL = fmt.Sprintf("%s/repos/%s/%s/contents",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo))
+	} else {
+		reqURL = fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escapePath(path))
+	}
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("list contents %s: %w", path, err)
+	}
+
+	var entries []ContentEntry
+	if err := json.Unmarshal(body, &entries); err != nil {
+		// GitHub returns a single object when path is a file (not an array).
+		var single contentResponse
+		if err2 := json.Unmarshal(body, &single); err2 != nil {
+			return nil, fmt.Errorf("parse contents JSON: %w", err)
+		}
+		if single.Name == "" && single.Path == "" {
+			return nil, fmt.Errorf("parse contents JSON: empty response for path %q", path)
+		}
+		entries = []ContentEntry{{
+			Name: single.Name,
+			Path: single.Path,
+			Type: single.Type,
+		}}
+	}
+	return entries, nil
+}
+
+// GetAllFilesInPath recursively fetches all file contents under a path.
+// If the path is a file, returns just that file's content.
+// If the path is a directory, recursively fetches all files within it.
+func (c *Client) GetAllFilesInPath(ctx context.Context, owner, repo, path string) (map[string]string, error) {
+	results := make(map[string]string)
+
+	entries, err := c.ListContents(ctx, owner, repo, path)
+	if err != nil {
+		if !IsNotFound(err) {
+			return nil, fmt.Errorf("list contents %q: %w", path, err)
+		}
+		// 404 means path may be a file — try fetching directly.
+		content, fileErr := c.GetFileContent(ctx, owner, repo, path)
+		if fileErr != nil {
+			return nil, fmt.Errorf("path %q is neither a file nor directory: %w", path, fileErr)
+		}
+		results[path] = content
+		return results, nil
+	}
+
+	for _, entry := range entries {
+		switch entry.Type {
+		case "file":
+			content, err := c.GetFileContent(ctx, owner, repo, entry.Path)
+			if err != nil {
+				slog.Warn("could not fetch file from patterns repo", "file", entry.Path, "error", err)
+				continue
+			}
+			results[entry.Path] = content
+		case "dir":
+			subResults, err := c.GetAllFilesInPath(ctx, owner, repo, entry.Path)
+			if err != nil {
+				slog.Warn("could not recurse into directory", "dir", entry.Path, "error", err)
+				continue
+			}
+			for k, v := range subResults {
+				results[k] = v
+			}
+		}
+	}
+	return results, nil
+}
+
+// --- Review methods ---
+
+// PostReview submits a review to a PR.
+// event should be one of "APPROVE", "REQUEST_CHANGES", or "COMMENT".
+// commitID anchors the review to a specific commit SHA. If empty, defaults to current HEAD.
+// comments are optional inline comments; GitHub uses diff hunk position (not line numbers).
+// Note: unlike Gitea, GitHub does not support deleting submitted reviews.
+// Use COMMENT event to supersede old reviews.
+func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, event, body, commitID string, comments []ReviewComment) (*Review, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	payload := struct {
+		Body     string          `json:"body"`
+		Event    string          `json:"event"`
+		CommitID string          `json:"commit_id,omitempty"`
+		Comments []ReviewComment `json:"comments,omitempty"`
+	}{
+		Body:     body,
+		Event:    event,
+		CommitID: commitID,
+		Comments: comments,
+	}
+
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return nil, fmt.Errorf("marshal review payload: %w", err)
+	}
+
+	respBody, err := c.doRequestWithBody(ctx, http.MethodPost, reqURL, data)
+	if err != nil {
+		return nil, fmt.Errorf("post review: %w", err)
+	}
+
+	var review Review
+	if err := json.Unmarshal(respBody, &review); err != nil {
+		return nil, fmt.Errorf("parse review response: %w", err)
+	}
+	return &review, nil
+}
+
+// ListReviews returns all reviews on a pull request.
+// GitHub paginates via Link header; this method uses per_page=100.
+func (c *Client) ListReviews(ctx context.Context, owner, repo string, number int) ([]Review, error) {
+	const perPage = 100
+	var all []Review
+	for page := 1; ; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews?per_page=%d&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, perPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("list reviews (page %d): %w", page, err)
+		}
+		var batch []Review
+		if err := json.Unmarshal(body, &batch); err != nil {
+			return nil, fmt.Errorf("parse reviews (page %d): %w", page, err)
+		}
+		all = append(all, batch...)
+		if len(batch) < perPage {
+			break
+		}
+	}
+	return all, nil
+}
+
+// DeleteReview attempts to delete a pull request review.
+// GitHub only allows deleting PENDING (draft) reviews. Submitted reviews cannot
+// be deleted via the API; this method returns a descriptive error in that case.
+// review-bot callers should handle this error gracefully (e.g., by not attempting
+// supersede and instead posting a new review alongside the old one).
+func (c *Client) DeleteReview(ctx context.Context, owner, repo string, number int, reviewID int64) error {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews/%d",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, reviewID)
+
+	// nil body: the GitHub DELETE endpoint for reviews requires no request body.
+	_, err := c.doRequestWithBody(ctx, http.MethodDelete, reqURL, nil)
+	if err != nil {
+		return fmt.Errorf("delete review: %w", err)
+	}
+	return nil
+}
+
+// GetAuthenticatedUser returns the login of the authenticated user.
+func (c *Client) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	reqURL := c.baseURL + "/user"
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return "", fmt.Errorf("get authenticated user: %w", err)
+	}
+	var result struct {
+		Login string `json:"login"`
+	}
+	if err := json.Unmarshal(body, &result); err != nil {
+		return "", fmt.Errorf("parse user response: %w", err)
+	}
+	return result.Login, nil
+}
+
+// RequestReviewer adds a user as a requested reviewer on a pull request.
+// This is idempotent — requesting an already-requested reviewer is a no-op.
+func (c *Client) RequestReviewer(ctx context.Context, owner, repo string, number int, reviewer string) error {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/requested_reviewers",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	payload := struct {
+		Reviewers []string `json:"reviewers"`
+	}{Reviewers: []string{reviewer}}
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("marshal reviewer request: %w", err)
+	}
+
+	_, err = c.doRequestWithBody(ctx, http.MethodPost, reqURL, data)
+	if err != nil {
+		return fmt.Errorf("request reviewer: %w", err)
+	}
+	return nil
+}
+
+// --- helpers ---
+
+// escapePath escapes each segment of a relative file path for use in URLs.
+// Slashes are preserved as path separators; other special characters are escaped.
+func escapePath(p string) string {
+	parts := strings.Split(p, "/")
+	for i, part := range parts {
+		parts[i] = url.PathEscape(part)
+	}
+	return strings.Join(parts, "/")
+}
diff --git a/github/client_test.go b/github/client_test.go
index bb2f9f9..8aa22fb 100644
--- a/github/client_test.go
+++ b/github/client_test.go
@@ -2,7 +2,9 @@ package github
 
 import (
 	"context"
+	"encoding/json"
 	"errors"
+	"fmt"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -656,3 +658,475 @@ func TestRedactURL_UserinfoWithQuery(t *testing.T) {
 		t.Errorf("redactURL = %q, want %q", got, want)
 	}
 }
+
+// --- Tests for API methods ---
+
+func TestGetPullRequest_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/repos/owner/repo/pulls/42" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"title":"Test PR","body":"description","head":{"sha":"abc123","ref":"feature"},"draft":false}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	pr, err := c.GetPullRequest(context.Background(), "owner", "repo", 42)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if pr.Title != "Test PR" {
+		t.Errorf("Title = %q, want %q", pr.Title, "Test PR")
+	}
+	if pr.Head.Sha != "abc123" {
+		t.Errorf("Head.Sha = %q, want %q", pr.Head.Sha, "abc123")
+	}
+	if pr.Head.Ref != "feature" {
+		t.Errorf("Head.Ref = %q, want %q", pr.Head.Ref, "feature")
+	}
+}
+
+func TestGetPullRequest_NotFound(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusNotFound)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	_, err := c.GetPullRequest(context.Background(), "owner", "repo", 99)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !IsNotFound(err) {
+		t.Errorf("expected IsNotFound=true, got false for error: %v", err)
+	}
+}
+
+func TestGetPullRequestDiff_Success(t *testing.T) {
+	const wantDiff = "diff --git a/foo.go b/foo.go\n--- a/foo.go\n+++ b/foo.go\n"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Header.Get("Accept") != "application/vnd.github.diff" {
+			t.Errorf("Accept = %q, want application/vnd.github.diff", r.Header.Get("Accept"))
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(wantDiff))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	diff, err := c.GetPullRequestDiff(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if diff != wantDiff {
+		t.Errorf("diff = %q, want %q", diff, wantDiff)
+	}
+}
+
+func TestGetPullRequestFiles_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`[{"filename":"foo.go","status":"modified"},{"filename":"bar.go","status":"added"}]`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	files, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(files) != 2 {
+		t.Fatalf("len(files) = %d, want 2", len(files))
+	}
+	if files[0].Filename != "foo.go" || files[0].Status != "modified" {
+		t.Errorf("files[0] = %+v, want {foo.go modified}", files[0])
+	}
+}
+
+func TestGetPullRequestFiles_Paginated(t *testing.T) {
+	page := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		page++
+		if page == 1 {
+			// Return 100 items (page full → expect another request)
+			items := make([]map[string]string, 100)
+			for i := range items {
+				items[i] = map[string]string{"filename": fmt.Sprintf("file%d.go", i), "status": "modified"}
+			}
+			data, _ := json.Marshal(items)
+			w.WriteHeader(http.StatusOK)
+			w.Write(data)
+			return
+		}
+		// Page 2: return fewer than perPage → stop
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`[{"filename":"last.go","status":"added"}]`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	files, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(files) != 101 {
+		t.Errorf("len(files) = %d, want 101", len(files))
+	}
+	if page != 2 {
+		t.Errorf("page = %d, want 2", page)
+	}
+}
+
+func TestGetCommitStatuses_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		// GitHub uses "state" field
+		w.Write([]byte(`[{"state":"success","context":"ci/test","description":"Tests pass","target_url":"https://ci.example.com"}]`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	statuses, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "deadbeef")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(statuses) != 1 {
+		t.Fatalf("len(statuses) = %d, want 1", len(statuses))
+	}
+	if statuses[0].Status != "success" {
+		t.Errorf("Status = %q, want %q", statuses[0].Status, "success")
+	}
+	if statuses[0].Context != "ci/test" {
+		t.Errorf("Context = %q, want %q", statuses[0].Context, "ci/test")
+	}
+}
+
+func TestGetFileContent_Base64(t *testing.T) {
+	// "hello world\n" base64-encoded with embedded newlines (as GitHub does it)
+	encoded := "aGVsbG8gd29ybGQK"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if !strings.HasSuffix(r.URL.Path, "/contents/README.md") {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"name":"README.md","path":"README.md","type":"file","content":"` + encoded + `","encoding":"base64"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	content, err := c.GetFileContent(context.Background(), "owner", "repo", "README.md")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "hello world\n" {
+		t.Errorf("content = %q, want %q", content, "hello world\n")
+	}
+}
+
+func TestGetFileContent_Base64WithNewlines(t *testing.T) {
+	// GitHub embeds newlines in base64 content for readability (every 60 chars)
+	// Test that we strip them correctly before decoding
+	// "hello world\n" = aGVsbG8gd29ybGQK — split it with embedded \n
+	encoded := "aGVs\nbG8g\nd29y\nbGQK"
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		// JSON-encode the embedded newlines as \n
+		body := `{"name":"README.md","path":"README.md","type":"file","content":"aGVs\nbG8g\nd29y\nbGQK","encoding":"base64"}`
+		_ = encoded // suppress unused warning
+		w.Write([]byte(body))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	content, err := c.GetFileContent(context.Background(), "owner", "repo", "README.md")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "hello world\n" {
+		t.Errorf("content = %q, want %q", content, "hello world\n")
+	}
+}
+
+func TestGetFileContent_IsDirectory(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"name":"docs","path":"docs","type":"dir","content":"","encoding":""}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	_, err := c.GetFileContent(context.Background(), "owner", "repo", "docs")
+	if err == nil {
+		t.Fatal("expected error for directory, got nil")
+	}
+}
+
+func TestGetFileContentRef_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Query().Get("ref") != "main" {
+			t.Errorf("ref = %q, want %q", r.URL.Query().Get("ref"), "main")
+		}
+		encoded := "dGVzdA==" // "test"
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"name":"foo.go","path":"foo.go","type":"file","content":"` + encoded + `","encoding":"base64"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	content, err := c.GetFileContentRef(context.Background(), "owner", "repo", "foo.go", "main")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "test" {
+		t.Errorf("content = %q, want %q", content, "test")
+	}
+}
+
+func TestListContents_Directory(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`[{"name":"foo.go","path":"foo.go","type":"file"},{"name":"bar","path":"bar","type":"dir"}]`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	entries, err := c.ListContents(context.Background(), "owner", "repo", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 2 {
+		t.Fatalf("len(entries) = %d, want 2", len(entries))
+	}
+	if entries[0].Name != "foo.go" || entries[0].Type != "file" {
+		t.Errorf("entries[0] = %+v, unexpected", entries[0])
+	}
+}
+
+func TestListContents_SingleFile(t *testing.T) {
+	// GitHub returns a single object when the path is a file
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"name":"README.md","path":"README.md","type":"file","content":"","encoding":""}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	entries, err := c.ListContents(context.Background(), "owner", "repo", "README.md")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("len(entries) = %d, want 1", len(entries))
+	}
+	if entries[0].Name != "README.md" {
+		t.Errorf("entries[0].Name = %q, want README.md", entries[0].Name)
+	}
+}
+
+func TestPostReview_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			t.Errorf("method = %s, want POST", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/1/reviews" {
+			t.Errorf("path = %s, unexpected", r.URL.Path)
+		}
+		var payload map[string]interface{}
+		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
+			t.Errorf("decode body: %v", err)
+		}
+		if payload["event"] != "APPROVE" {
+			t.Errorf("event = %v, want APPROVE", payload["event"])
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"id":99,"body":"looks good","user":{"login":"bot"},"state":"APPROVED"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	review, err := c.PostReview(context.Background(), "owner", "repo", 1, "APPROVE", "looks good", "abc", nil)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if review.ID != 99 {
+		t.Errorf("review.ID = %d, want 99", review.ID)
+	}
+	if review.User.Login != "bot" {
+		t.Errorf("review.User.Login = %q, want bot", review.User.Login)
+	}
+}
+
+func TestPostReview_Unauthorized(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusUnauthorized)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("bad-tok", srv.URL, AllowInsecureHTTPForTest())
+	_, err := c.PostReview(context.Background(), "owner", "repo", 1, "APPROVE", "body", "", nil)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got false for error: %v", err)
+	}
+}
+
+func TestListReviews_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`[{"id":1,"body":"review 1","user":{"login":"alice"},"state":"APPROVED"},{"id":2,"body":"review 2","user":{"login":"bob"},"state":"CHANGES_REQUESTED"}]`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	reviews, err := c.ListReviews(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(reviews) != 2 {
+		t.Fatalf("len(reviews) = %d, want 2", len(reviews))
+	}
+	if reviews[0].ID != 1 || reviews[0].User.Login != "alice" {
+		t.Errorf("reviews[0] = %+v, unexpected", reviews[0])
+	}
+}
+
+func TestDeleteReview_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodDelete {
+			t.Errorf("method = %s, want DELETE", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/1/reviews/42" {
+			t.Errorf("path = %s, unexpected", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	err := c.DeleteReview(context.Background(), "owner", "repo", 1, 42)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestDeleteReview_SubmittedReview(t *testing.T) {
+	// GitHub returns 422 for trying to delete a non-pending review
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(http.StatusUnprocessableEntity)
+		w.Write([]byte(`{"message":"Can only delete a pending review"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	err := c.DeleteReview(context.Background(), "owner", "repo", 1, 99)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+}
+
+func TestGetAuthenticatedUser_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/user" {
+			t.Errorf("path = %s, want /user", r.URL.Path)
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write([]byte(`{"login":"review-bot","id":12345}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	login, err := c.GetAuthenticatedUser(context.Background())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if login != "review-bot" {
+		t.Errorf("login = %q, want review-bot", login)
+	}
+}
+
+func TestRequestReviewer_Success(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			t.Errorf("method = %s, want POST", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/1/requested_reviewers" {
+			t.Errorf("path = %s, unexpected", r.URL.Path)
+		}
+		var payload map[string]interface{}
+		if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
+			t.Errorf("decode body: %v", err)
+		}
+		reviewers, ok := payload["reviewers"].([]interface{})
+		if !ok || len(reviewers) != 1 || reviewers[0] != "reviewer1" {
+			t.Errorf("reviewers = %v, unexpected", payload["reviewers"])
+		}
+		w.WriteHeader(http.StatusCreated)
+		w.Write([]byte(`{}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("tok", srv.URL, AllowInsecureHTTPForTest())
+	err := c.RequestReviewer(context.Background(), "owner", "repo", 1, "reviewer1")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestPostReview_RejectsHTTP(t *testing.T) {
+	// PostReview must reject http:// base URLs — tokens must not be sent in plaintext.
+	c := NewClient("tok", "http://127.0.0.1:1")
+	_, err := c.PostReview(context.Background(), "owner", "repo", 1, "APPROVE", "body", "", nil)
+	if err == nil {
+		t.Fatal("expected error for HTTP base URL in PostReview")
+	}
+	if !strings.Contains(err.Error(), "refusing HTTP request") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDeleteReview_RejectsHTTP(t *testing.T) {
+	// DeleteReview must reject http:// base URLs — tokens must not be sent in plaintext.
+	c := NewClient("tok", "http://127.0.0.1:1")
+	err := c.DeleteReview(context.Background(), "owner", "repo", 1, 42)
+	if err == nil {
+		t.Fatal("expected error for HTTP base URL in DeleteReview")
+	}
+	if !strings.Contains(err.Error(), "refusing HTTP request") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestRequestReviewer_RejectsHTTP(t *testing.T) {
+	// RequestReviewer must reject http:// base URLs — tokens must not be sent in plaintext.
+	c := NewClient("tok", "http://127.0.0.1:1")
+	err := c.RequestReviewer(context.Background(), "owner", "repo", 1, "reviewer1")
+	if err == nil {
+		t.Fatal("expected error for HTTP base URL in RequestReviewer")
+	}
+	if !strings.Contains(err.Error(), "refusing HTTP request") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestEscapePath_SpecialChars(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"README.md", "README.md"},
+		{"docs/guide.md", "docs/guide.md"},
+		{"path with spaces/file.md", "path%20with%20spaces/file.md"},
+		{"path/with [brackets]/file.md", "path/with%20%5Bbrackets%5D/file.md"},
+	}
+	for _, tt := range tests {
+		got := escapePath(tt.input)
+		if got != tt.want {
+			t.Errorf("escapePath(%q) = %q, want %q", tt.input, got, tt.want)
+		}
+	}
+}