feat(cmd): add VCS routing for GitHub PR reviews

Wire up the new GitHub API methods to the review-bot CLI via VCS
type detection. review-bot can now review PRs on both Gitea and
GitHub (including GitHub Enterprise Server).

Changes:
- vcs.go: define vcsClient interface with all PR operations
  - giteaVCSAdapter: wraps gitea.Client, satisfies vcsClient + giteaExtClient
  - githubVCSAdapter: wraps github.Client, satisfies vcsClient
  - giteaExtClient: Gitea-specific extension (supersede, comment resolution)
- main.go: detect VCS type via VCS_TYPE env var (auto-detects github.com URLs)
  - Creates appropriate client (gitea or github) based on vcs_type
  - GitHub API URL derived from server URL (github.com → api.github.com,
    GHES → /api/v3)
  - All main flow uses vcsClient interface
  - Gitea-specific supersede operations gated via giteaExtClient type assertion
  - GitHub: logs info when skipping supersede (not supported)
- Removes old giteaClientAdapter (replaced by giteaVCSAdapter in vcs.go)
- giteaVCSAdapter satisfies review.GiteaClient for persona loading

GitHub limitations handled gracefully:
- Review supersede skipped (GitHub doesn't allow editing submitted reviews)
- DeleteReview returns error for non-pending reviews (documented in adapter)
- Inline comments use absolute line + side='RIGHT' instead of diff position

Closes #130.

Co-authored-by: Rodin <rodin@forgedthought.ai>

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)
-}

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"},

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)
+}