fix(cmd): remove duplicate doc comment and double blank line

Address sonnet-review feedback on PR #106:

- Document that the type assertion in supersedeOldReviews is guaranteed to
  succeed given the caller's provider switch, with the !ok branch guarding
  against future refactors (comment 18889).
- Clarify that vcsURL is only used in the Gitea path for constructing
  review permalink URLs (comment 18890).
- Add note explaining why the page-limit warning in ListReviews only fires
  when the final page is full, confirming the logic is intentional
  (comment 18891).

cmd/review-bot/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"log/slog"
@@ -13,6 +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"
 	"gitea.weiker.me/rodin/review-bot/vcs"
@@ -54,12 +56,15 @@ func main() {
 	// Logging flags
 	logFormat := flag.String("log-format", envOrDefault("LOG_FORMAT", "text"), "Log output format: text or json")
 	verbosity := flag.String("verbosity", envOrDefault("LOG_VERBOSITY", "info"), "Log verbosity: debug, info, warn, error")
-	// CLI flags
+	// VCS flags
-	giteaURL := flag.String("gitea-url", envOrDefault("GITEA_URL", envOrDefault("GITHUB_SERVER_URL", "")), "Gitea instance URL")
+	provider := flag.String("provider", envOrDefault("VCS_PROVIDER", "gitea"), "VCS provider: gitea or github")
-	repo := flag.String("repo", envOrDefault("GITEA_REPO", envOrDefault("GITHUB_REPOSITORY", "")), "Repository (owner/name)")
+	baseURL := flag.String("base-url", envOrDefault("VCS_BASE_URL", ""), "VCS API base URL (for github provider; defaults to https://api.github.com)")
+	vcsURL := flag.String("vcs-url", envOrDefault("VCS_URL", envOrDefault("GITEA_URL", envOrDefault("GITHUB_SERVER_URL", ""))), "VCS instance URL (Gitea) [deprecated alias: --gitea-url]")
+	// Keep --gitea-url as backward-compatible alias (flag package doesn't support aliases natively, handle below)
+	repo := flag.String("repo", envOrDefault("VCS_REPO", envOrDefault("GITEA_REPO", envOrDefault("GITHUB_REPOSITORY", ""))), "Repository (owner/name)")
 	prNum := flag.String("pr", envOrDefault("PR_NUMBER", ""), "Pull request number")
 	reviewerName := flag.String("reviewer-name", envOrDefault("REVIEWER_NAME", ""), "Reviewer display name")
-	reviewerToken := flag.String("reviewer-token", envOrDefault("REVIEWER_TOKEN", ""), "Gitea token for posting review")
+	reviewerToken := flag.String("reviewer-token", envOrDefault("REVIEWER_TOKEN", ""), "VCS token for posting review")
 	llmBaseURL := flag.String("llm-base-url", envOrDefault("LLM_BASE_URL", ""), "LLM API base URL")
 	llmAPIKey := flag.String("llm-api-key", envOrDefault("LLM_API_KEY", ""), "LLM API key")
 	llmModel := flag.String("llm-model", envOrDefault("LLM_MODEL", ""), "LLM model name")
@@ -80,6 +85,18 @@ func main() {
 	aicoreAPIURL := flag.String("aicore-api-url", envOrDefault("AICORE_API_URL", ""), "SAP AI Core API URL (for provider=aicore)")
 	aicoreResourceGroup := flag.String("aicore-resource-group", envOrDefault("AICORE_RESOURCE_GROUP", "default"), "SAP AI Core resource group (for provider=aicore)")
 
+	// Register --gitea-url as a backward-compatible alias for --vcs-url.
+	// StringVar shares the *string pointer with vcsURL, so whichever flag is
+	// set last by flag.Parse wins — both point to the same underlying value.
+	// NOTE: If a user passes both --vcs-url and --gitea-url, the last one on
+	// the command line takes effect (standard flag package behavior). This is
+	// acceptable since --gitea-url is deprecated and both serve the same purpose.
+	//
+	// ORDERING: This must remain AFTER vcsURL's flag.String declaration and BEFORE
+	// flag.Parse(). The *vcsURL dereference captures the env-var-resolved default
+	// at registration time; moving flag.Parse() above this line would break it.
+	flag.StringVar(vcsURL, "gitea-url", *vcsURL, "Deprecated: use --vcs-url instead")
+
 	flag.Parse()
 
 	if *versionFlag {
@@ -92,12 +109,25 @@ func main() {
 
 	slog.Info("review-bot starting", "version", version)
 
+	// Validate VCS provider
+	switch *provider {
+	case "gitea", "github":
+		// valid
+	default:
+		fmt.Fprintf(os.Stderr, "Error: invalid --provider %q (valid: gitea, github)\n", *provider)
+		os.Exit(1)
+	}
+
 	// Validate required fields
-	// For aicore provider, llm-base-url and llm-api-key are not required
 	isAICore := llm.Provider(*llmProvider) == llm.ProviderAICore
-	if *giteaURL == "" || *repo == "" || *prNum == "" || *reviewerToken == "" || *llmModel == "" {
+	if *repo == "" || *prNum == "" || *reviewerToken == "" || *llmModel == "" {
 		fmt.Fprintf(os.Stderr, "Error: missing required flags or environment variables\n\n")
-		fmt.Fprintf(os.Stderr, "Required: --gitea-url, --repo, --pr, --reviewer-token, --llm-model\n")
+		fmt.Fprintf(os.Stderr, "Required: --repo, --pr, --reviewer-token, --llm-model\n")
+		os.Exit(1)
+	}
+	// --vcs-url is required only for gitea provider
+	if *provider == "gitea" && *vcsURL == "" {
+		fmt.Fprintf(os.Stderr, "Error: --vcs-url (or --gitea-url) is required for provider=gitea\n")
 		os.Exit(1)
 	}
 	if !isAICore && (*llmBaseURL == "" || *llmAPIKey == "") {
@@ -116,8 +146,6 @@ func main() {
 		os.Exit(1)
 	}
 
-	// NOTE: Persona loading deferred until after Gitea client init to support repo personas
-
 	// Validate reviewer-name: only safe characters allowed in sentinel
 	if err := validateReviewerName(*reviewerName); err != nil {
 		slog.Error("invalid reviewer name", "error", err)
@@ -139,8 +167,25 @@ func main() {
 		os.Exit(1)
 	}
 
-	// Initialize clients
+	// Initialize VCS client
-	giteaClient := gitea.NewClient(*giteaURL, *reviewerToken)
+	var client vcs.Client
+	switch *provider {
+	case "gitea":
+		giteaClient := gitea.NewClient(*vcsURL, *reviewerToken)
+		client = gitea.NewAdapter(giteaClient)
+	case "github":
+		ghBaseURL := *baseURL
+		if ghBaseURL == "" {
+			ghBaseURL = "https://api.github.com"
+		}
+		client = github.NewClient(*reviewerToken, ghBaseURL)
+	default:
+		fmt.Fprintf(os.Stderr, "Error: unhandled provider %q\n", *provider)
+		os.Exit(1)
+	}
+	slog.Info("VCS client initialized", "provider", *provider)
+
+	// Initialize LLM client
 	llmClient := llm.NewClient(*llmBaseURL, *llmAPIKey, *llmModel)
 	if *llmTemp < 0 || *llmTemp > 2 {
 		slog.Error("invalid LLM temperature", "temperature", *llmTemp, "range", "0-2")
@@ -174,16 +219,13 @@ func main() {
 	ctx, cancel := context.WithTimeout(context.Background(), overallTimeout)
 	defer cancel()
 
-	// Load persona if specified (after Gitea client init to support repo personas)
+	// Load persona if specified
 	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, client, owner, repoName)
 		if err != nil {
 			slog.Warn("could not load repo personas", "repo", owner+"/"+repoName, "error", err)
-			// Continue with built-in personas only.
-			// NOTE: repoPersonas is nil here, but map indexing on a nil map is safe in Go
-			// (returns the zero value), so the fallback to built-in below works correctly.
 		}
 		if p, ok := repoPersonas[*personaName]; ok {
 			persona = p
@@ -214,7 +256,7 @@ 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 := client.GetPullRequest(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch PR", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -222,7 +264,7 @@ 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 := client.GetPullRequestDiff(ctx, owner, repoName, prNumber)
 	if err != nil {
 		slog.Error("failed to fetch diff", "pr", prNumber, "error", err)
 		os.Exit(1)
@@ -231,21 +273,21 @@ func main() {
 
 	// Step 3: Fetch full file content for modified files
 	fileContext := ""
-	files, err := giteaClient.GetPullRequestFiles(ctx, owner, repoName, prNumber)
+	files, err := client.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, client, owner, repoName, pr.Head.Ref, files)
 		slog.Debug("fetched file context", "files", len(files))
 	}
 
 	// Step 4: Check CI status
 	ciPassed := true
 	ciDetails := ""
-	if pr.Head.Sha != "" {
+	if pr.Head.SHA != "" {
-		statuses, err := giteaClient.GetCommitStatuses(ctx, owner, repoName, pr.Head.Sha)
+		statuses, err := client.GetCommitStatuses(ctx, owner, repoName, pr.Head.SHA)
 		if err != nil {
-			slog.Warn("could not fetch CI status", "sha", pr.Head.Sha, "error", err)
+			slog.Warn("could not fetch CI status", "sha", pr.Head.SHA, "error", err)
 		} else {
 			ciPassed, ciDetails = evaluateCIStatus(statuses)
 			slog.Info("CI status checked", "passed", ciPassed)
@@ -255,7 +297,7 @@ func main() {
 	// Step 5: Load conventions file if specified
 	conventions := ""
 	if *conventionsFile != "" {
-		content, err := giteaClient.GetFileContent(ctx, owner, repoName, *conventionsFile)
+		content, err := client.GetFileContent(ctx, owner, repoName, *conventionsFile, "")
 		if err != nil {
 			slog.Warn("could not load conventions file", "file", *conventionsFile, "error", err)
 		} else {
@@ -267,7 +309,7 @@ func main() {
 	// Step 6: Load patterns from external repo if specified
 	patterns := ""
 	if *patternsRepo != "" {
-		patterns = fetchPatterns(ctx, giteaClient, *patternsRepo, *patternsFiles)
+		patterns = fetchPatterns(ctx, client, *patternsRepo, *patternsFiles)
 		slog.Debug("loaded patterns", "repo", *patternsRepo, "bytes", len(patterns))
 	}
 
@@ -360,15 +402,16 @@ func main() {
 	}
 
 	// Add commit footer so readers know which commit was evaluated
-	if pr.Head.Sha != "" {
+	if pr.Head.SHA != "" {
-		shortSHA := pr.Head.Sha
+		shortSHA := pr.Head.SHA
 		if len(shortSHA) > 8 {
 			shortSHA = shortSHA[:8]
 		}
 		reviewBody += fmt.Sprintf("\n\n---\n*Evaluated against %s*", shortSHA)
 	}
 
-	event := review.GiteaEvent(result.Verdict)
+	// Map verdict to canonical review event
+	event := verdictToEvent(result.Verdict)
 
 	if *dryRun {
 		fmt.Println("--- DRY RUN ---")
@@ -380,14 +423,13 @@ func main() {
 	sentinel := fmt.Sprintf("<!-- review-bot:%s -->", *reviewerName)
 
 	// Stale check: verify HEAD hasn't moved since we started
-	evaluatedSHA := pr.Head.Sha
+	evaluatedSHA := pr.Head.SHA
 	var currentSHA string
-	currentPR, err := giteaClient.GetPullRequest(ctx, owner, repoName, prNumber)
+	currentPR, err := client.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
 	} else {
-		currentSHA = currentPR.Head.Sha
+		currentSHA = currentPR.Head.SHA
 	}
 	if shouldSkipStaleReview(evaluatedSHA, currentSHA) {
 		slog.Warn("HEAD moved during review — skipping stale review",
@@ -397,17 +439,24 @@ func main() {
 		return
 	}
 
-	// Map findings to inline comments for lines present in the diff
+	// Build line→position map for inline comments
-	diffRanges := gitea.ParseDiffNewLines(diff)
+	lineToPosition := vcs.BuildLineToPositionMap(diff)
-	var inlineComments []gitea.ReviewComment
+	var inlineComments []vcs.ReviewComment
 	for _, f := range result.Findings {
-		if f.File != "" && f.Line > 0 && diffRanges.Contains(f.File, f.Line) {
+		if f.File == "" || f.Line <= 0 {
-			inlineComments = append(inlineComments, gitea.ReviewComment{
+			continue
-				Path:        f.File,
-				NewPosition: int64(f.Line),
-				Body:        fmt.Sprintf("**[%s]** %s", f.Severity, f.Finding),
-			})
 		}
+		pos, ok := lineToPosition[f.File][f.Line]
+		if !ok {
+			slog.Warn("line not in diff, skipping comment", "file", f.File, "line", f.Line)
+			continue
+		}
+		inlineComments = append(inlineComments, vcs.ReviewComment{
+			Path:     f.File,
+			Position: pos,
+			CommitID: pr.Head.SHA,
+			Body:     fmt.Sprintf("**[%s]** %s", f.Severity, f.Finding),
+		})
 	}
 	if len(inlineComments) > 0 {
 		slog.Debug("attaching inline comments", "count", len(inlineComments))
@@ -416,10 +465,9 @@ func main() {
 	// --- Review update strategy ---
 	// 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 []vcs.Review
-	var oldReviews []gitea.Review
 	if *reviewerName != "" {
-		existingReviews, err := giteaClient.ListReviews(ctx, owner, repoName, prNumber)
+		existingReviews, err := client.ListReviews(ctx, owner, repoName, prNumber)
 		if err != nil {
 			slog.Warn("could not list existing reviews", "pr", prNumber, "error", err)
 		} else {
@@ -431,74 +479,137 @@ func main() {
 		}
 	}
 
-	// Self-request as reviewer (ensures we appear in required-reviewer checks)
+	// Self-request as reviewer (Gitea-specific; ensures we appear in required-reviewer checks)
-	authUser, err := giteaClient.GetAuthenticatedUser(ctx)
+	if giteaAdapter, ok := client.(*gitea.Adapter); ok {
-	if err != nil {
+		authUser, err := client.GetAuthenticatedUser(ctx)
-		slog.Warn("could not determine authenticated user for reviewer self-request", "error", err)
+		if err != nil {
-	} else if authUser != "" {
+			slog.Warn("could not determine authenticated user for reviewer self-request", "error", err)
-		if err := giteaClient.RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
+		} else if authUser != "" {
-			slog.Warn("could not self-request as reviewer", "user", authUser, "error", err)
+			if err := giteaAdapter.Underlying().RequestReviewer(ctx, owner, repoName, prNumber, authUser); err != nil {
-		} else {
+				slog.Warn("could not self-request as reviewer", "user", authUser, "error", err)
-			slog.Debug("self-requested as reviewer", "user", authUser, "pr", prNumber)
+			} else {
+				slog.Debug("self-requested as reviewer", "user", authUser, "pr", prNumber)
+			}
 		}
+	} else {
+		slog.Debug("RequestReviewer not supported for provider, skipping")
 	}
 
 	// POST new review
 	slog.Info("posting review", "event", event, "pr", prNumber)
-	posted, err := giteaClient.PostReview(ctx, owner, repoName, prNumber, event, reviewBody, inlineComments)
+	reviewReq := vcs.ReviewRequest{
+		Body:     reviewBody,
+		Event:    event,
+		Comments: inlineComments,
+	}
+	posted, err := client.PostReview(ctx, owner, repoName, prNumber, reviewReq)
 	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
+	// Supersede all old reviews
 	if len(oldReviews) > 0 {
-		newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(*giteaURL, "/"), owner, repoName, prNumber, posted.ID)
+		if err := supersedeOldReviews(ctx, client, *provider, *vcsURL, owner, repoName, prNumber, oldReviews, posted.ID, sentinel); err != nil {
-		for _, oldReview := range oldReviews {
+			slog.Error("failed to supersede old reviews", "error", err)
-			cid, err := giteaClient.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, prNumber, oldReview.ID)
+			os.Exit(1)
-			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 {
-				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)
-			if err != nil {
-				slog.Warn("could not list old review comments for resolution", "review_id", oldReview.ID, "error", err)
-				continue
-			}
-			resolved, failed := 0, 0
-			for _, c := range oldComments {
-				if c.ID == 0 {
-					continue
-				}
-				if err := giteaClient.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
-					slog.Debug("could not resolve inline comment", "comment_id", c.ID, "error", err)
-					failed++
-				} else {
-					resolved++
-				}
-			}
-			if resolved > 0 {
-				slog.Info("resolved old inline comments", "review_id", oldReview.ID, "count", resolved, "pr", prNumber)
-			}
-			if failed > 0 {
-				slog.Warn("some inline comments could not be resolved", "review_id", oldReview.ID, "failed", failed, "pr", prNumber)
-			}
 		}
 	}
+}
 
+// verdictToEvent maps a verdict string from the LLM response to a canonical vcs.ReviewEvent.
+func verdictToEvent(verdict string) vcs.ReviewEvent {
+	switch verdict {
+	case "APPROVE":
+		return vcs.ReviewEventApprove
+	case "REQUEST_CHANGES":
+		return vcs.ReviewEventRequestChanges
+	default:
+		return vcs.ReviewEventComment
+	}
+}
+
+// supersedeOldReviews marks prior reviews as superseded so only the latest review is visible.
+// For GitHub: dismisses old reviews (vcsURL is unused in this path).
+// For Gitea: edits the review body with a link to the new review and resolves inline comments.
+//
+// The vcsURL parameter is only used in the Gitea path to construct review permalink URLs;
+// it is accepted unconditionally to keep the function signature uniform across providers.
+func supersedeOldReviews(ctx context.Context, client vcs.Client, provider, vcsURL, owner, repoName string, prNumber int, oldReviews []vcs.Review, newReviewID int64, sentinel string) error {
+	switch provider {
+	case "github":
+		// Best-effort dismissal: attempt all reviews, join any errors.
+		var errs []error
+		for _, old := range oldReviews {
+			if err := client.DismissReview(ctx, owner, repoName, prNumber, old.ID, "Superseded by new review"); err != nil {
+				slog.Warn("failed to dismiss review", "id", old.ID, "error", err)
+				errs = append(errs, fmt.Errorf("dismiss review %d: %w", old.ID, err))
+			} else {
+				slog.Info("dismissed old review", "review_id", old.ID, "new_review_id", newReviewID, "pr", prNumber)
+			}
+		}
+		return errors.Join(errs...)
+	case "gitea":
+		// Continue to Gitea-specific logic below the switch.
+	default:
+		return fmt.Errorf("supersedeOldReviews: unsupported provider %q", provider)
+	}
+
+	// The type assertion below is guaranteed to succeed: the caller's provider switch
+	// ensures we only reach this point when provider == "gitea", and the gitea provider
+	// always constructs a *gitea.Adapter. The !ok branch guards against future refactors
+	// (e.g. wrapping the adapter in a decorator) that would silently break this path.
+	giteaAdapter, ok := client.(*gitea.Adapter)
+	if !ok {
+		return fmt.Errorf("expected gitea.Adapter for gitea provider, got %T", client)
+	}
+	underlying := giteaAdapter.Underlying()
+
+	newReviewURL := fmt.Sprintf("%s/%s/%s/pulls/%d#pullrequestreview-%d", strings.TrimRight(vcsURL, "/"), owner, repoName, prNumber, newReviewID)
+	for _, oldReview := range oldReviews {
+		cid, err := underlying.GetTimelineReviewCommentIDForReview(ctx, owner, repoName, 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 := underlying.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", newReviewID, "pr", prNumber)
+
+		// Resolve old review's inline comments
+		oldComments, err := underlying.ListReviewComments(ctx, owner, repoName, prNumber, oldReview.ID)
+		if err != nil {
+			slog.Warn("could not list old review comments for resolution", "review_id", oldReview.ID, "error", err)
+			continue
+		}
+		resolved, failed := 0, 0
+		for _, c := range oldComments {
+			if c.ID == 0 {
+				continue
+			}
+			if err := underlying.ResolveComment(ctx, owner, repoName, c.ID); err != nil {
+				slog.Debug("could not resolve inline comment", "comment_id", c.ID, "error", err)
+				failed++
+			} else {
+				resolved++
+			}
+		}
+		if resolved > 0 {
+			slog.Info("resolved old inline comments", "review_id", oldReview.ID, "count", resolved, "pr", prNumber)
+		}
+		if failed > 0 {
+			slog.Warn("some inline comments could not be resolved", "review_id", oldReview.ID, "failed", failed, "pr", prNumber)
+		}
+	}
+	return nil
 }
 
 // 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 vcs.PRReader, owner, repo, ref string, files []vcs.ChangedFile) string {
 	var sb strings.Builder
 	for _, f := range files {
 		if ctx.Err() != nil {
@@ -507,7 +618,7 @@ func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, re
 		if f.Status == "removed" {
 			continue // Skip deleted files
 		}
-		content, err := client.GetFileContentRef(ctx, owner, repo, f.Filename, ref)
+		content, err := client.GetFileContentAtRef(ctx, owner, repo, f.Filename, ref)
 		if err != nil {
 			slog.Warn("could not fetch file content", "file", f.Filename, "error", err)
 			continue
@@ -524,7 +635,7 @@ func fetchFileContext(ctx context.Context, client *gitea.Client, owner, repo, re
 // patternsRepo is comma-separated list of owner/name repos.
 // 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.
-func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patternsFiles string) string {
+func fetchPatterns(ctx context.Context, client vcs.FileReader, patternsRepo, patternsFiles string) string {
 	var sb strings.Builder
 
 	repos := strings.Split(patternsRepo, ",")
@@ -554,7 +665,7 @@ func fetchPatterns(ctx context.Context, client *gitea.Client, patternsRepo, patt
 				continue
 			}
 
-			files, err := client.GetAllFilesInPath(ctx, owner, repo, path)
+			files, err := vcs.GetAllFilesInPath(ctx, client, owner, repo, path)
 			if err != nil {
 				slog.Warn("could not fetch patterns", "path", path, "repo", repoRef, "error", err)
 				continue
@@ -593,18 +704,20 @@ func isPatternFile(path string) bool {
 }
 
 // evaluateCIStatus checks if all CI statuses indicate success.
-func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details string) {
+// Returns passed=true if no checks have failed (pending checks are not treated as failures).
+func evaluateCIStatus(statuses []vcs.CommitStatus) (passed bool, details string) {
 	if len(statuses) == 0 {
 		return true, "no CI statuses found"
 	}
 
 	var failed []string
+	var pending int
 	for _, s := range statuses {
 		switch s.Status {
 		case "success":
 			// good
 		case "pending":
-			// treat pending as not-failed
+			pending++
 		case "failure", "error":
 			failed = append(failed, fmt.Sprintf("%s: %s", s.Context, s.Description))
 		}
@@ -613,6 +726,9 @@ func evaluateCIStatus(statuses []gitea.CommitStatus) (passed bool, details strin
 	if len(failed) > 0 {
 		return false, strings.Join(failed, "; ")
 	}
+	if pending > 0 {
+		return true, fmt.Sprintf("no failures (%d pending)", pending)
+	}
 	return true, "all checks passed"
 }
 
@@ -728,10 +844,10 @@ func buildSupersededBody(originalBody, commitSHA, newReviewURL, sentinel string)
 }
 
 // hasSharedToken detects if another review-bot role posted under the same
-// Gitea user. This indicates misconfiguration where two roles share a token
+// VCS user. This indicates misconfiguration where two roles share a token
-// instead of having separate Gitea accounts. Returns true if shared token
+// instead of having separate 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 []vcs.Review, ownSentinel string) bool {
 	ownLogin := ""
 	for _, r := range reviews {
 		if strings.Contains(r.Body, ownSentinel) {
@@ -744,7 +860,7 @@ func hasSharedToken(reviews []gitea.Review, ownSentinel string) bool {
 	}
 	for _, r := range reviews {
 		if r.User.Login == ownLogin && strings.Contains(r.Body, "<!-- review-bot:") && !strings.Contains(r.Body, ownSentinel) {
-			slog.Warn("shared token detected — another review-bot role is using the same Gitea user",
+			slog.Warn("shared token detected — another review-bot role is using the same VCS user",
 				"sibling_role", extractSentinelName(r.Body), "user", ownLogin)
 			return true
 		}
@@ -765,29 +881,27 @@ func extractSentinelName(body string) string {
 	if end < 0 {
 		return "unknown"
 	}
-	return rest[:end]
+	name := rest[:end]
+	// Sanitize: strip control characters to prevent log injection.
+	name = strings.Map(func(r rune) rune {
+		if r < 0x20 || r == 0x7f {
+			return -1
+		}
+		return r
+	}, name)
+	if len(name) > 64 {
+		name = name[:64]
+	}
+	if name == "" {
+		return "unknown"
+	}
+	return name
 }
 
-// findOwnReview locates the most recent non-superseded review matching the sentinel.
-func findOwnReview(reviews []gitea.Review, sentinel string) *gitea.Review {
-	var best *gitea.Review
-	for i := range reviews {
-		if !strings.Contains(reviews[i].Body, sentinel) {
-			continue
-		}
-		if strings.Contains(reviews[i].Body, "~~Original review~~") {
-			continue
-		}
-		if best == nil || reviews[i].ID > best.ID {
-			best = &reviews[i]
-		}
-	}
-	return best
-}
 
 // findAllOwnReviews returns all non-superseded reviews matching the sentinel.
-func findAllOwnReviews(reviews []gitea.Review, sentinel string) []gitea.Review {
+func findAllOwnReviews(reviews []vcs.Review, sentinel string) []vcs.Review {
-	var result []gitea.Review
+	var result []vcs.Review
 	for i := range reviews {
 		if !strings.Contains(reviews[i].Body, sentinel) {
 			continue
@@ -812,35 +926,3 @@ func shouldSkipStaleReview(evaluatedSHA, currentSHA string) bool {
 	}
 	return evaluatedSHA != currentSHA
 }
-
-// giteaClientAdapter adapts gitea.Client to vcs.FileReader 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) ([]vcs.ContentEntry, error) {
-	entries, err := a.client.ListContents(ctx, owner, repo, path)
-	if err != nil {
-		return nil, err
-	}
-	result := make([]vcs.ContentEntry, len(entries))
-	for i, e := range entries {
-		result[i] = vcs.ContentEntry{
-			Name: e.Name,
-			Path: e.Path,
-			Type: e.Type,
-		}
-	}
-	return result, nil
-}
-
-func (a *giteaClientAdapter) GetFileContent(ctx context.Context, owner, repo, filePath, ref string) (string, error) {
-	if ref != "" {
-		return a.client.GetFileContentRef(ctx, owner, repo, filePath, ref)
-	}
-	return a.client.GetFileContent(ctx, owner, repo, filePath)
-}

cmd/review-bot/main_test.go

@@ -10,7 +10,7 @@ import (
 	"strings"
 	"testing"
 
-	"gitea.weiker.me/rodin/review-bot/gitea"
+	"gitea.weiker.me/rodin/review-bot/vcs"
 )
 
 func TestValidateReviewerName(t *testing.T) {
@@ -107,9 +107,7 @@ func TestValidateWorkspacePath(t *testing.T) {
 			workspace: tmpDir,
 			path:      "/etc/passwd",
 			wantErr:   true,
-			// Go 1.21+ filepath.Join normalizes absolute paths: Join("/tmp/x", "/etc/passwd")
+			errMatch:  "failed to resolve",
-			// becomes "/tmp/x/etc/passwd", which is within workspace but doesn't exist.
-			errMatch: "failed to resolve",
 		},
 		{
 			name:      "nonexistent file",
@@ -154,15 +152,14 @@ func TestValidateWorkspacePath(t *testing.T) {
 	}
 }
 
-func makeReview(id int64, login, state string, stale bool, body string) gitea.Review {
+func makeReview(id int64, login, state string, stale bool, body string) vcs.Review {
-	r := gitea.Review{
+	return vcs.Review{
 		ID:    id,
 		Body:  body,
+		User:  vcs.UserInfo{Login: login},
 		State: state,
 		Stale: stale,
 	}
-	r.User.Login = login
-	return r
 }
 
 func TestBuildSupersededBody(t *testing.T) {
@@ -213,96 +210,11 @@ func TestBuildSupersededBodyShortSHA(t *testing.T) {
 	}
 }
 
-func TestFindOwnReview(t *testing.T) {
-	tests := []struct {
-		name     string
-		reviews  []gitea.Review
-		sentinel string
-		wantID   int64
-		wantNil  bool
-	}{
-		{
-			name:     "no reviews",
-			reviews:  nil,
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantNil:  true,
-		},
-		{
-			name: "found by sentinel",
-			reviews: []gitea.Review{
-				makeReview(42, "bot", "APPROVED", false, "review body\n<!-- review-bot:sonnet -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantID:   42,
-		},
-		{
-			name: "wrong sentinel",
-			reviews: []gitea.Review{
-				makeReview(42, "bot", "APPROVED", false, "body\n<!-- review-bot:gpt -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantNil:  true,
-		},
-		{
-			name: "multiple reviews, returns first match",
-			reviews: []gitea.Review{
-				makeReview(10, "bot", "APPROVED", false, "old\n<!-- review-bot:gpt -->"),
-				makeReview(20, "bot", "APPROVED", false, "new\n<!-- review-bot:sonnet -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantID:   20,
-		},
-		{
-			name: "skips superseded review",
-			reviews: []gitea.Review{
-				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 -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantID:   20,
-		},
-		{
-			name: "only superseded reviews exist",
-			reviews: []gitea.Review{
-				makeReview(10, "bot", "APPROVED", false, "~~Original review~~\n\n<!-- review-bot:sonnet -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantNil:  true,
-		},
-		{
-			name: "picks highest ID among matches",
-			reviews: []gitea.Review{
-				makeReview(50, "bot", "APPROVED", false, "v1\n<!-- review-bot:sonnet -->"),
-				makeReview(30, "bot", "APPROVED", false, "v0\n<!-- review-bot:sonnet -->"),
-			},
-			sentinel: "<!-- review-bot:sonnet -->",
-			wantID:   50,
-		},
-	}
-
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			got := findOwnReview(tc.reviews, tc.sentinel)
-			if tc.wantNil {
-				if got != nil {
-					t.Errorf("findOwnReview() = %v, want nil", got)
-				}
-			} else {
-				if got == nil {
-					t.Fatal("findOwnReview() = nil, want non-nil")
-				}
-				if got.ID != tc.wantID {
-					t.Errorf("findOwnReview().ID = %d, want %d", got.ID, tc.wantID)
-				}
-			}
-		})
-	}
-}
 
 func TestHasSharedToken(t *testing.T) {
 	tests := []struct {
 		name     string
-		reviews  []gitea.Review
+		reviews  []vcs.Review
 		sentinel string
 		want     bool
 	}{
@@ -314,36 +226,36 @@ func TestHasSharedToken(t *testing.T) {
 		},
 		{
 			name: "no own review yet - cannot detect",
-			reviews: []gitea.Review{
+			reviews: []vcs.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "other"}, Body: "<!-- review-bot:gpt --> body"},
+				makeReview(1, "other", "APPROVED", false, "<!-- review-bot:gpt --> body"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "separate users - no shared token",
-			reviews: []gitea.Review{
+			reviews: []vcs.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				makeReview(1, "sonnet-review-bot", "APPROVED", false, "<!-- review-bot:sonnet --> body"),
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "security-review-bot"}, Body: "<!-- review-bot:security --> body"},
+				makeReview(2, "security-review-bot", "APPROVED", false, "<!-- review-bot:security --> body"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     false,
 		},
 		{
 			name: "shared token detected - same user different sentinels",
-			reviews: []gitea.Review{
+			reviews: []vcs.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				makeReview(1, "sonnet-review-bot", "APPROVED", false, "<!-- review-bot:sonnet --> body"),
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "sonnet-review-bot"}, Body: "<!-- review-bot:security --> body"},
+				makeReview(2, "sonnet-review-bot", "APPROVED", false, "<!-- review-bot:security --> body"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
 		},
 		{
 			name: "three roles same user",
-			reviews: []gitea.Review{
+			reviews: []vcs.Review{
-				{ID: 1, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:sonnet --> body"},
+				makeReview(1, "bot", "APPROVED", false, "<!-- review-bot:sonnet --> body"),
-				{ID: 2, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:security --> body"},
+				makeReview(2, "bot", "APPROVED", false, "<!-- review-bot:security --> body"),
-				{ID: 3, User: struct{ Login string `json:"login"` }{Login: "bot"}, Body: "<!-- review-bot:gpt --> body"},
+				makeReview(3, "bot", "APPROVED", false, "<!-- review-bot:gpt --> body"),
 			},
 			sentinel: "<!-- review-bot:sonnet -->",
 			want:     true,
@@ -507,7 +419,7 @@ func TestIsPatternFile(t *testing.T) {
 func TestEvaluateCIStatus(t *testing.T) {
 	tests := []struct {
 		name       string
-		statuses   []gitea.CommitStatus
+		statuses   []vcs.CommitStatus
 		wantPassed bool
 		wantSubstr string
 	}{
@@ -519,7 +431,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "all success",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
@@ -528,7 +440,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "one failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -537,7 +449,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "error status",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "error", Context: "ci/lint", Description: "Lint error"},
 			},
 			wantPassed: false,
@@ -545,16 +457,16 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "pending treated as not-failed",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "pending", Context: "ci/build", Description: "In progress"},
 				{Status: "success", Context: "ci/test", Description: "Tests passed"},
 			},
 			wantPassed: true,
-			wantSubstr: "all checks passed",
+			wantSubstr: "no failures",
 		},
 		{
 			name: "multiple failures",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "failure", Context: "ci/build", Description: "Build failed"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
 			},
@@ -563,7 +475,7 @@ func TestEvaluateCIStatus(t *testing.T) {
 		},
 		{
 			name: "mixed with pending and failure",
-			statuses: []gitea.CommitStatus{
+			statuses: []vcs.CommitStatus{
 				{Status: "success", Context: "ci/build", Description: "Build passed"},
 				{Status: "pending", Context: "ci/deploy", Description: "Deploying"},
 				{Status: "failure", Context: "ci/test", Description: "Tests failed"},
@@ -792,7 +704,7 @@ func TestMainSubprocess_InvalidReviewerName(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
+			"--vcs-url", "http://localhost",
 			"--repo", "owner/repo",
 			"--pr", "1",
 			"--reviewer-name", "invalid name",
@@ -820,7 +732,7 @@ func TestMainSubprocess_InvalidRepo(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
+			"--vcs-url", "http://localhost",
 			"--repo", "invalidrepo",
 			"--pr", "1",
 			"--reviewer-token", "tok",
@@ -847,7 +759,7 @@ func TestMainSubprocess_InvalidPRNumber(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
+			"--vcs-url", "http://localhost",
 			"--repo", "owner/repo",
 			"--pr", "notanumber",
 			"--reviewer-token", "tok",
@@ -874,7 +786,7 @@ func TestMainSubprocess_InvalidTemperature(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
+			"--vcs-url", "http://localhost",
 			"--repo", "owner/repo",
 			"--pr", "1",
 			"--reviewer-token", "tok",
@@ -902,7 +814,7 @@ func TestMainSubprocess_InvalidProvider(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
 		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
+			"--vcs-url", "http://localhost",
 			"--repo", "owner/repo",
 			"--pr", "1",
 			"--reviewer-token", "tok",
@@ -926,7 +838,35 @@ func TestMainSubprocess_InvalidProvider(t *testing.T) {
 	}
 }
 
-// cleanEnv returns environ without any GITEA/LLM/REVIEWER env vars that would
+func TestMainSubprocess_InvalidVCSProvider(t *testing.T) {
+	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
+		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+		os.Args = []string{"review-bot",
+			"--provider", "invalid",
+			"--vcs-url", "http://localhost",
+			"--repo", "owner/repo",
+			"--pr", "1",
+			"--reviewer-token", "tok",
+			"--llm-base-url", "http://localhost",
+			"--llm-api-key", "key",
+			"--llm-model", "model",
+		}
+		main()
+		return
+	}
+
+	cmd := exec.Command(os.Args[0], "-test.run=TestMainSubprocess_InvalidVCSProvider")
+	cmd.Env = append(cleanEnv(), "TEST_SUBPROCESS_MAIN=1")
+	out, err := cmd.CombinedOutput()
+	if err == nil {
+		t.Fatal("expected non-zero exit with invalid VCS provider")
+	}
+	if !strings.Contains(string(out), "invalid --provider") {
+		t.Errorf("expected error about invalid --provider, got: %s", out)
+	}
+}
+
+// cleanEnv returns environ without any GITEA/LLM/REVIEWER/VCS env vars that would
 // interfere with testing missing-flag scenarios.
 func cleanEnv() []string {
 	var env []string
@@ -934,6 +874,7 @@ func cleanEnv() []string {
 		key := strings.SplitN(e, "=", 2)[0]
 		switch {
 		case strings.HasPrefix(key, "GITEA_"),
+			strings.HasPrefix(key, "VCS_"),
 			strings.HasPrefix(key, "LLM_"),
 			strings.HasPrefix(key, "REVIEWER_"),
 			strings.HasPrefix(key, "PR_"),
@@ -951,12 +892,12 @@ func cleanEnv() []string {
 }
 
 func TestFindAllOwnReviews(t *testing.T) {
-	reviews := []gitea.Review{
+	reviews := []vcs.Review{
-		{ID: 1, Body: "<!-- review-bot:sonnet -->\nfirst review"},
+		makeReview(1, "bot", "APPROVED", false, "<!-- review-bot:sonnet -->\nfirst review"),
-		{ID: 2, Body: "<!-- review-bot:gpt -->\nother bot"},
+		makeReview(2, "bot", "APPROVED", false, "<!-- review-bot:gpt -->\nother bot"),
-		{ID: 3, Body: "<!-- review-bot:sonnet -->\nsecond review"},
+		makeReview(3, "bot", "APPROVED", false, "<!-- review-bot:sonnet -->\nsecond review"),
-		{ID: 4, Body: "~~Original review~~\n<!-- review-bot:sonnet -->\nsuperseded"},
+		makeReview(4, "bot", "APPROVED", false, "~~Original review~~\n<!-- review-bot:sonnet -->\nsuperseded"),
-		{ID: 5, Body: "<!-- review-bot:sonnet -->\nthird review"},
+		makeReview(5, "bot", "APPROVED", false, "<!-- review-bot:sonnet -->\nthird review"),
 	}
 
 	got := findAllOwnReviews(reviews, "<!-- review-bot:sonnet -->")
@@ -1020,3 +961,23 @@ func TestShouldSkipStaleReview(t *testing.T) {
 		})
 	}
 }
+
+func TestVerdictToEvent(t *testing.T) {
+	tests := []struct {
+		verdict string
+		want    vcs.ReviewEvent
+	}{
+		{"APPROVE", vcs.ReviewEventApprove},
+		{"REQUEST_CHANGES", vcs.ReviewEventRequestChanges},
+		{"COMMENT", vcs.ReviewEventComment},
+		{"other", vcs.ReviewEventComment},
+		{"", vcs.ReviewEventComment},
+	}
+
+	for _, tc := range tests {
+		got := verdictToEvent(tc.verdict)
+		if got != tc.want {
+			t.Errorf("verdictToEvent(%q) = %q, want %q", tc.verdict, got, tc.want)
+		}
+	}
+}

gitea/position.go

@@ -11,6 +11,7 @@ import (
 type PositionMap struct {
 	// files maps filename → (position → new-file line number).
 	// Deletion lines are mapped to -1 (no new-file line).
+	// Hunk-header lines are mapped to 0 (no new-file line).
 	files map[string]map[int]int
 	// maxPositions caches the highest position number per file,
 	// tracked during construction to avoid O(n) scans at translate time.
@@ -19,8 +20,8 @@ type PositionMap struct {
 
 // Translate converts a GitHub diff-position to a new-file line number for a given file.
 // Returns an error if the file is not in the diff or the position is out of range.
-// If the position targets a deletion line, it maps to the nearest non-deletion line below;
+// If the position targets a deletion or hunk-header line, it maps to the nearest
-// if no such line exists, returns an error.
+// context/addition line below; if no such line exists, returns an error.
 func (pm *PositionMap) Translate(file string, position int) (int, error) {
 	if pm == nil || pm.files == nil {
 		return 0, fmt.Errorf("empty position map")
@@ -41,14 +42,18 @@ func (pm *PositionMap) Translate(file string, position int) (int, error) {
 	}
 
 	// lineNum == -1 means this position is a deletion line.
-	// Map to the nearest non-deletion line below.
+	// lineNum == 0 means this position is a hunk-header line.
-	if lineNum == -1 {
+	// Both map to the nearest context/addition line below.
+	if lineNum <= 0 {
 		maxPos := pm.maxPosition(file)
 		for p := position + 1; p <= maxPos; p++ {
 			if ln, exists := fileMap[p]; exists && ln > 0 {
 				return ln, nil
 			}
 		}
+		if lineNum == 0 {
+			return 0, fmt.Errorf("position %d targets a hunk-header line with no subsequent new-file line in %q", position, file)
+		}
 		return 0, fmt.Errorf("position %d targets a deletion line with no subsequent new-file line in %q", position, file)
 	}
 
@@ -70,6 +75,7 @@ func (pm *PositionMap) maxPosition(file string) int {
 //   - A new @@ hunk within the same file continues incrementing (does not reset)
 //   - Position maps to the new file line number for additions and context lines
 //   - Deletion lines have a position but no new-file line number (stored as -1)
+//   - Hunk-header lines have a position but no new-file line number (stored as 0)
 func BuildPositionToLineMap(diff string) *PositionMap {
 	pm := &PositionMap{
 		files:        make(map[string]map[int]int),
@@ -126,6 +132,7 @@ func BuildPositionToLineMap(diff string) *PositionMap {
 		// Parse hunk headers
 		if strings.HasPrefix(line, "@@") && currentFile != "" {
 			position++
+			pm.files[currentFile][position] = 0 // sentinel: hunk-header has no new-file line
 			pm.maxPositions[currentFile] = position
 			newLine = parseHunkStart(line)
 			continue

gitea/position_test.go

@@ -272,3 +272,112 @@ diff --git a/b.go b/b.go
 		t.Errorf("Translate(b.go, 3) = %d, want 2", got)
 	}
 }
+
+func TestTranslate_HunkHeaderPosition_SingleHunk(t *testing.T) {
+	// Position 1 is the @@ hunk-header line.
+	// It should resolve to the first context/addition line below (new line 16).
+	diff := `diff --git a/file.go b/file.go
+index abc..def 100644
+--- a/file.go
++++ b/file.go
+@@ -16,4 +16,5 @@ func example() {
+ context line
+-deleted line
++added line
+ context after
+`
+	pm := BuildPositionToLineMap(diff)
+
+	got, err := pm.Translate("file.go", 1)
+	if err != nil {
+		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
+	}
+	if got != 16 {
+		t.Errorf("Translate(file.go, 1) = %d, want 16 (first context/addition line in hunk)", got)
+	}
+}
+
+func TestTranslate_HunkHeaderPosition_MultiHunk(t *testing.T) {
+	// First hunk: @@ is pos 1, then " line1" (pos 2), "-old" (pos 3), "+new" (pos 4)
+	// Second hunk: @@ is pos 5, then " func foo() {" (pos 6), "+// added" (pos 7), etc.
+	// Translating position 5 (second @@) should resolve to new line 10.
+	diff := `diff --git a/file.go b/file.go
+--- a/file.go
++++ b/file.go
+@@ -1,3 +1,3 @@ package main
+ line1
+-old
++new
+@@ -10,3 +10,4 @@ func foo() {
+ func foo() {
++	// added
+ 	return
+ }
+`
+	pm := BuildPositionToLineMap(diff)
+
+	// Position 5 is the second @@ hunk-header — should resolve to new line 10
+	got, err := pm.Translate("file.go", 5)
+	if err != nil {
+		t.Fatalf("Translate(file.go, 5): unexpected error: %v", err)
+	}
+	if got != 10 {
+		t.Errorf("Translate(file.go, 5) = %d, want 10 (first context/addition line in second hunk)", got)
+	}
+
+	// Also verify first hunk header at position 1 resolves to new line 1
+	got, err = pm.Translate("file.go", 1)
+	if err != nil {
+		t.Fatalf("Translate(file.go, 1): unexpected error: %v", err)
+	}
+	if got != 1 {
+		t.Errorf("Translate(file.go, 1) = %d, want 1 (first context/addition line in first hunk)", got)
+	}
+}
+
+func TestTranslate_HunkHeaderPosition_NewFile(t *testing.T) {
+	// New file: @@ -0,0 +1,3 @@ is position 1.
+	// Should resolve to new line 1 (the first addition).
+	diff := `diff --git a/new.go b/new.go
+new file mode 100644
+--- /dev/null
++++ b/new.go
+@@ -0,0 +1,3 @@
++package main
++
++func init() {}
+`
+	pm := BuildPositionToLineMap(diff)
+
+	got, err := pm.Translate("new.go", 1)
+	if err != nil {
+		t.Fatalf("Translate(new.go, 1): unexpected error: %v", err)
+	}
+	if got != 1 {
+		t.Errorf("Translate(new.go, 1) = %d, want 1 (first addition line)", got)
+	}
+}
+
+func TestTranslate_HunkHeaderAtEnd(t *testing.T) {
+	// A hunk-header at the last position with no subsequent new-file line should error.
+	// This is the hunk-header equivalent of TestBuildPositionToLineMap_DeletionAtEnd.
+	diff := `diff --git a/file.go b/file.go
+--- a/file.go
++++ b/file.go
+@@ -1,2 +1,2 @@ package main
+ line1
+-old
++new
+@@ -10,2 +10,1 @@ func foo() {
+-removed
+`
+	pm := BuildPositionToLineMap(diff)
+
+	// Position 5 is the second @@ hunk-header; the only line after it (pos 6) is a
+	// deletion (lineNum == -1), so there's no positive new-file line to resolve to.
+	// The hunk-header lookup should fail.
+	_, err := pm.Translate("file.go", 5)
+	if err == nil {
+		t.Error("expected error for hunk-header at end with no subsequent new-file line")
+	}
+}

github/client.go

@@ -0,0 +1,388 @@
+// Package github provides a client for the GitHub API.
+// It supports pull request operations, file content retrieval, CI status checks,
+// and directory listing for both github.com and GitHub Enterprise.
+package github
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const (
+	defaultBaseURL = "https://api.github.com"
+	userAgent      = "review-bot/1.0"
+
+	// maxResponseBytes limits successful response body reads to 10 MiB.
+	maxResponseBytes = 10 * 1024 * 1024
+
+	// maxRetryAttempts is the number of times doRequest will attempt a request.
+	// The retry backoff slice must have length maxRetryAttempts-1.
+	maxRetryAttempts = 3
+)
+
+// APIError represents an HTTP error response from the GitHub API.
+// It carries the status code so callers can distinguish between
+// different failure modes (e.g. 404 vs 500).
+//
+// The Body field stores up to 4 KiB of the raw response for programmatic
+// inspection. Error() truncates to 200 bytes for safe logging, but callers
+// should avoid logging or propagating Body directly in production since it may
+// contain sensitive details from the upstream server.
+type APIError struct {
+	StatusCode int
+	Body       string
+}
+
+func (e *APIError) Error() string {
+	body := e.Body
+	if len(body) > 200 {
+		body = body[:200] + "...(truncated)"
+	}
+	// Sanitize newlines to prevent log injection from upstream response bodies.
+	body = strings.ReplaceAll(body, "\n", " ")
+	body = strings.ReplaceAll(body, "\r", " ")
+	return fmt.Sprintf("HTTP %d: %s", e.StatusCode, body)
+}
+
+// IsNotFound reports whether an error is an API 404 response.
+func IsNotFound(err error) bool {
+	if apiErr, ok := asAPIError(err); ok {
+		return apiErr.StatusCode == http.StatusNotFound
+	}
+	return false
+}
+
+// IsUnauthorized reports whether an error is an API 401 response.
+func IsUnauthorized(err error) bool {
+	if apiErr, ok := asAPIError(err); ok {
+		return apiErr.StatusCode == http.StatusUnauthorized
+	}
+	return false
+}
+
+func asAPIError(err error) (*APIError, bool) {
+	if err == nil {
+		return nil, false
+	}
+	var target *APIError
+	if errors.As(err, &target) {
+		return target, true
+	}
+	return nil, false
+}
+
+// clientConfig holds optional configuration for NewClient.
+type clientConfig struct {
+	allowInsecureHTTP bool
+}
+
+// ClientOption configures optional behavior of NewClient.
+type ClientOption func(*clientConfig)
+
+// AllowInsecureHTTP permits the client to use HTTP (non-TLS) base URLs.
+// This should only be used for trusted internal deployments or testing.
+func AllowInsecureHTTP() ClientOption {
+	return func(c *clientConfig) {
+		c.allowInsecureHTTP = true
+	}
+}
+
+// Client interacts with the GitHub API.
+// A Client is safe for concurrent use by multiple goroutines.
+// 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 {
+	baseURL           string
+	token             string
+	allowInsecureHTTP bool
+	httpClient        *http.Client
+
+	// retryBackoff defines the delays between retry attempts for 429 responses.
+	// retryBackoff[i] is the delay before attempt i+1 (after attempt i fails).
+	// If nil, defaults to {1s, 2s}. Set to shorter durations in tests via SetRetryBackoff.
+	retryBackoff []time.Duration
+}
+
+// defaultCheckRedirect is the redirect policy used by NewClient and SetHTTPClient(nil).
+// It rejects HTTPS→HTTP protocol downgrades (to prevent plaintext leakage) and strips
+// the Authorization header on cross-host redirects to prevent credential leakage to
+// third-party hosts (e.g. CDN redirects from GitHub).
+func defaultCheckRedirect(req *http.Request, via []*http.Request) error {
+	if len(via) >= 10 {
+		return fmt.Errorf("stopped after 10 redirects")
+	}
+	// Guard: net/http guarantees len(via) >= 1 but this is undocumented;
+	// defend against zero-length to avoid panic on index out of range.
+	if len(via) == 0 {
+		return nil
+	}
+	prev := via[len(via)-1]
+	// Reject protocol downgrade: HTTPS→HTTP leaks request metadata over plaintext.
+	if prev.URL.Scheme == "https" && req.URL.Scheme == "http" {
+		return fmt.Errorf("refusing redirect from HTTPS to HTTP (%s → %s)", prev.URL.Host, req.URL.Host)
+	}
+	// Strip Authorization on cross-host redirect to avoid leaking credentials
+	// to third-party hosts (GitHub legitimately redirects to CDN hosts).
+	if req.URL.Host != prev.URL.Host {
+		req.Header.Del("Authorization")
+	}
+	return nil
+}
+
+// NewClient creates a new GitHub API client.
+// If baseURL is empty, it defaults to https://api.github.com.
+// For GitHub Enterprise, pass the API base URL (e.g. https://github.concur.com/api/v3).
+// The baseURL must use HTTPS; pass AllowInsecureHTTP() as an option to permit HTTP
+// for trusted internal deployments (e.g. local testing).
+func NewClient(token, baseURL string, opts ...ClientOption) *Client {
+	if baseURL == "" {
+		baseURL = defaultBaseURL
+	}
+	cfg := clientConfig{}
+	for _, o := range opts {
+		o(&cfg)
+	}
+	return &Client{
+		baseURL:           strings.TrimRight(baseURL, "/"),
+		allowInsecureHTTP: cfg.allowInsecureHTTP,
+		token:             token,
+		httpClient: &http.Client{
+			Timeout:       30 * time.Second,
+			CheckRedirect: defaultCheckRedirect,
+		},
+	}
+}
+
+// SetHTTPClient sets the underlying HTTP client used for requests.
+// This is intended for test setup only to inject mock transports; it must be
+// called before any goroutines issue requests.
+//
+// Passing nil restores the default client (30s timeout + auth-stripping
+// CheckRedirect policy matching NewClient).
+//
+// Callers providing a non-nil client are responsible for configuring a safe
+// CheckRedirect policy. Without one, the default net/http behavior will follow
+// redirects and may forward the Authorization header to untrusted hosts.
+func (c *Client) SetHTTPClient(hc *http.Client) {
+	if hc == nil {
+		hc = &http.Client{
+			Timeout:       30 * time.Second,
+			CheckRedirect: defaultCheckRedirect,
+		}
+	}
+	c.httpClient = hc
+}
+
+// SetRetryBackoff configures the retry backoff durations for testing.
+// It must be called before any goroutines issue requests.
+// The slice must have exactly maxRetryAttempts-1 entries (one delay per retry gap).
+// In production the default {1s, 2s} applies.
+func (c *Client) SetRetryBackoff(d []time.Duration) error {
+	if len(d) != maxRetryAttempts-1 {
+		return fmt.Errorf("github: backoff length %d does not match maxRetryAttempts-1 (%d)", len(d), maxRetryAttempts-1)
+	}
+	c.retryBackoff = d
+	return nil
+}
+
+// doWithRetry performs an HTTP request with retry on 429 rate limit responses.
+// It delegates request construction to buildReq, which is called on each attempt
+// to produce a fresh *http.Request (allowing body re-reads for POST/PUT).
+// It respects the Retry-After header when present (capped at maxRetryAfter).
+// Transport errors (network failures, context cancellation) are not retried.
+func (c *Client) doWithRetry(ctx context.Context, reqURL string, buildReq func() (*http.Request, error)) ([]byte, error) {
+	const maxRetryAfter = 120 * time.Second
+
+	// maxErrorBodyBytes limits how much of an error response body is stored.
+	// Kept small (4 KiB) to reduce the risk of sensitive data leakage if callers
+	// log APIError.Body directly. Error() further truncates to 200 bytes.
+	const maxErrorBodyBytes = 4 * 1024
+
+	// backoff holds per-attempt delays: backoff[i] is the delay before attempt i+1.
+	// Length must be maxRetryAttempts-1 (one entry per retry gap).
+	// SetRetryBackoff validates at configuration time; the default is always valid.
+	defaultBackoff := []time.Duration{1 * time.Second, 2 * time.Second}
+	var backoff []time.Duration
+	if c.retryBackoff != nil && len(c.retryBackoff) == maxRetryAttempts-1 {
+		backoff = make([]time.Duration, len(c.retryBackoff))
+		copy(backoff, c.retryBackoff)
+	} else {
+		backoff = make([]time.Duration, len(defaultBackoff))
+		copy(backoff, defaultBackoff)
+	}
+
+	// Reject non-HTTPS URLs early since the URL is immutable across retries.
+	if c.token != "" && !c.allowInsecureHTTP {
+		parsed, err := url.Parse(reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("parse request URL: %w", err)
+		}
+		if !strings.EqualFold(parsed.Scheme, "https") {
+			return nil, fmt.Errorf("refusing to send credentials over non-HTTPS URL %q (use AllowInsecureHTTP option for trusted networks)", reqURL)
+		}
+	}
+
+	var lastErr error
+	for attempt := 0; attempt < maxRetryAttempts; attempt++ {
+		if attempt > 0 {
+			var delay time.Duration
+			if attempt-1 < len(backoff) {
+				delay = backoff[attempt-1]
+			}
+			if delay > 0 {
+				timer := time.NewTimer(delay)
+				select {
+				case <-timer.C:
+					timer.Stop() // no-op after fire; kept for symmetry with the ctx.Done case
+				case <-ctx.Done():
+					timer.Stop()
+					return nil, ctx.Err()
+				}
+			}
+		}
+
+		req, err := buildReq()
+		if err != nil {
+			return nil, fmt.Errorf("create request: %w", err)
+		}
+
+		resp, err := c.httpClient.Do(req)
+		if err != nil {
+			return nil, fmt.Errorf("do request: %w", err)
+		}
+
+		// Capture response metadata before handleResponse takes body ownership.
+		respStatus := resp.StatusCode
+		retryAfterHeader := resp.Header.Get("Retry-After")
+
+		body, done, handleErr := c.handleResponse(resp, maxResponseBytes, maxErrorBodyBytes)
+		if done {
+			return body, handleErr
+		}
+		lastErr = handleErr
+
+		// Retry on 429 rate limit
+		if respStatus == http.StatusTooManyRequests && attempt < maxRetryAttempts-1 {
+			// Check for Retry-After header and override backoff if present.
+			// Supports both integer seconds (common) and HTTP-date format (RFC 7231).
+			if ra := retryAfterHeader; ra != "" {
+				if seconds, err := strconv.Atoi(ra); err == nil && seconds > 0 {
+					delay := time.Duration(seconds) * time.Second
+					if delay > maxRetryAfter {
+						delay = maxRetryAfter
+					}
+					if attempt < len(backoff) {
+						backoff[attempt] = delay
+					}
+				} else if retryAt, err := http.ParseTime(ra); err == nil {
+					delay := time.Until(retryAt)
+					if delay < 0 {
+						delay = 0
+					}
+					if delay > maxRetryAfter {
+						delay = maxRetryAfter
+					}
+					if attempt < len(backoff) {
+						backoff[attempt] = delay
+					}
+				}
+			}
+			continue
+		}
+
+		// Don't retry other errors
+		return nil, lastErr
+	}
+
+	return nil, lastErr
+}
+
+// doRequest performs an HTTP request with retry on 429 rate limit responses.
+// It respects the Retry-After header when present (capped at maxRetryAfter).
+// Transport errors (network failures, context cancellation) are not retried.
+func (c *Client) doRequest(ctx context.Context, method, reqURL string, accept string) ([]byte, error) {
+	buildReq := func() (*http.Request, error) {
+		req, err := http.NewRequestWithContext(ctx, method, reqURL, nil)
+		if err != nil {
+			return nil, err
+		}
+		if c.token != "" {
+			// Bearer is the OAuth2 standard and is accepted by GitHub for both
+			// classic PATs and fine-grained tokens. The alternative "token" scheme
+			// is GitHub-specific and offers no additional compatibility.
+			req.Header.Set("Authorization", "Bearer "+c.token)
+		}
+		req.Header.Set("User-Agent", userAgent)
+		if accept != "" {
+			req.Header.Set("Accept", accept)
+		} else {
+			req.Header.Set("Accept", "application/vnd.github+json")
+		}
+		return req, nil
+	}
+	return c.doWithRetry(ctx, reqURL, buildReq)
+}
+
+// handleResponse reads and closes the response body, returning the result.
+// It uses defer to ensure the body is always closed regardless of code path.
+// Returns (body, done, err) where done=true means the caller should return immediately.
+func (c *Client) handleResponse(resp *http.Response, maxRespBytes int, maxErrBytes int) ([]byte, bool, error) {
+	defer resp.Body.Close()
+
+	if resp.StatusCode >= 200 && resp.StatusCode < 300 {
+		body, err := io.ReadAll(io.LimitReader(resp.Body, int64(maxRespBytes)+1))
+		if err != nil {
+			return nil, true, fmt.Errorf("read response body: %w", err)
+		}
+		if len(body) > maxRespBytes {
+			return nil, true, fmt.Errorf("response body exceeded %d bytes", maxRespBytes)
+		}
+		return body, true, nil
+	}
+
+	errBody, readErr := io.ReadAll(io.LimitReader(resp.Body, int64(maxErrBytes)))
+	if readErr != nil && len(errBody) == 0 {
+		errBody = []byte(fmt.Sprintf("[error reading response body: %v]", readErr))
+	}
+	return nil, false, &APIError{StatusCode: resp.StatusCode, Body: string(errBody)}
+}
+
+// doGet is a convenience wrapper for GET requests with the default Accept header.
+func (c *Client) doGet(ctx context.Context, reqURL string) ([]byte, error) {
+	return c.doRequest(ctx, http.MethodGet, reqURL, "")
+}
+
+// doJSONRequest performs an HTTP request with a JSON body and returns the response body.
+// It delegates retry/backoff/429 handling to doWithRetry.
+// This is a general-purpose helper used by any method that needs to send JSON payloads
+// (e.g. PostReview, DismissReview).
+func (c *Client) doJSONRequest(ctx context.Context, method, reqURL string, payload any) ([]byte, error) {
+	jsonBody, err := json.Marshal(payload)
+	if err != nil {
+		return nil, fmt.Errorf("marshal request body: %w", err)
+	}
+
+	buildReq := func() (*http.Request, error) {
+		req, err := http.NewRequestWithContext(ctx, method, reqURL, bytes.NewReader(jsonBody))
+		if err != nil {
+			return nil, err
+		}
+		if c.token != "" {
+			req.Header.Set("Authorization", "Bearer "+c.token)
+		}
+		req.Header.Set("User-Agent", userAgent)
+		req.Header.Set("Accept", "application/vnd.github+json")
+		req.Header.Set("Content-Type", "application/json")
+		return req, nil
+	}
+	return c.doWithRetry(ctx, reqURL, buildReq)
+}

github/client_test.go

@@ -0,0 +1,651 @@
+package github
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestNewClient_DefaultBaseURL(t *testing.T) {
+	c := NewClient("test-token", "")
+	if c.baseURL != "https://api.github.com" {
+		t.Errorf("expected default base URL, got %q", c.baseURL)
+	}
+}
+
+func TestNewClient_CustomBaseURL(t *testing.T) {
+	c := NewClient("test-token", "https://github.concur.com/api/v3")
+	if c.baseURL != "https://github.concur.com/api/v3" {
+		t.Errorf("expected custom base URL, got %q", c.baseURL)
+	}
+}
+
+func TestNewClient_TrimsTrailingSlash(t *testing.T) {
+	c := NewClient("test-token", "https://github.concur.com/api/v3/")
+	if c.baseURL != "https://github.concur.com/api/v3" {
+		t.Errorf("expected trailing slash trimmed, got %q", c.baseURL)
+	}
+}
+
+func TestDoRequest_SetsAuthHeader(t *testing.T) {
+	var gotAuth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAuth = r.Header.Get("Authorization")
+		w.WriteHeader(200)
+		w.Write([]byte("{}"))
+	}))
+	defer srv.Close()
+
+	c := NewClient("my-token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	_, _ = c.doGet(context.Background(), srv.URL+"/test")
+
+	if gotAuth != "Bearer my-token" {
+		t.Errorf("expected Bearer auth, got %q", gotAuth)
+	}
+}
+
+func TestDoRequest_SetsDefaultAcceptHeader(t *testing.T) {
+	var gotAccept string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAccept = r.Header.Get("Accept")
+		w.WriteHeader(200)
+		w.Write([]byte("{}"))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	_, _ = c.doGet(context.Background(), srv.URL+"/test")
+
+	if gotAccept != "application/vnd.github+json" {
+		t.Errorf("expected default Accept header, got %q", gotAccept)
+	}
+}
+
+func TestDoRequest_429Retry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{10 * time.Millisecond, 10 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(body) != `{"ok":true}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+}
+
+func TestDoRequest_429ExhaustsRetries(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(429)
+		w.Write([]byte(`{"message":"rate limit"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error after exhausting retries")
+	}
+	apiErr, ok := err.(*APIError)
+	if !ok {
+		t.Fatalf("expected *APIError, got %T", err)
+	}
+	if apiErr.StatusCode != 429 {
+		t.Errorf("expected 429, got %d", apiErr.StatusCode)
+	}
+	if attempts != 3 {
+		t.Errorf("expected 3 attempts, got %d", attempts)
+	}
+}
+
+func TestDoRequest_404NoRetry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"not found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+	if attempts != 1 {
+		t.Errorf("expected 1 attempt (no retry on 404), got %d", attempts)
+	}
+}
+
+func TestDoRequest_401NoRetry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if attempts != 1 {
+		t.Errorf("expected 1 attempt (no retry on 401), got %d", attempts)
+	}
+}
+
+func TestIsNotFound(t *testing.T) {
+	err := &APIError{StatusCode: 404, Body: "not found"}
+	if !IsNotFound(err) {
+		t.Error("expected IsNotFound to return true for 404")
+	}
+	err2 := &APIError{StatusCode: 500, Body: "server error"}
+	if IsNotFound(err2) {
+		t.Error("expected IsNotFound to return false for 500")
+	}
+}
+
+func TestIsUnauthorized(t *testing.T) {
+	err := &APIError{StatusCode: 401, Body: "bad credentials"}
+	if !IsUnauthorized(err) {
+		t.Error("expected IsUnauthorized to return true for 401")
+	}
+}
+
+func TestAPIError_SanitizesNewlines(t *testing.T) {
+	err := &APIError{StatusCode: 500, Body: "line1\ninjected\rmore"}
+	msg := err.Error()
+	if strings.Contains(msg, "\n") || strings.Contains(msg, "\r") {
+		t.Errorf("expected newlines to be sanitized, got: %q", msg)
+	}
+	if !strings.Contains(msg, "line1 injected more") {
+		t.Errorf("expected sanitized body, got: %q", msg)
+	}
+}
+
+func TestDoRequest_429RetryAfterHeader(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping slow retry test in short mode")
+	}
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.Header().Set("Retry-After", "1")
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	// Use short backoff; Retry-After should override
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	start := time.Now()
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	elapsed := time.Since(start)
+
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(body) != `{"ok":true}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+	// Retry-After: 1 means at least 1 second delay
+	if elapsed < 900*time.Millisecond {
+		t.Errorf("expected ~1s delay from Retry-After, got %v", elapsed)
+	}
+}
+
+func TestDoRequest_RetryAfterDoesNotMutateBackoff(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping slow retry test in short mode")
+	}
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.Header().Set("Retry-After", "1")
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Verify the original retryBackoff slice was not mutated
+	if c.retryBackoff[0] != 1*time.Millisecond {
+		t.Errorf("retryBackoff[0] was mutated: got %v, want 1ms", c.retryBackoff[0])
+	}
+	if c.retryBackoff[1] != 1*time.Millisecond {
+		t.Errorf("retryBackoff[1] was mutated: got %v, want 1ms", c.retryBackoff[1])
+	}
+}
+
+func TestDoRequest_429RetryAfterHTTPDate(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping slow Retry-After HTTP-date test in short mode")
+	}
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			// Use HTTP-date format (RFC 7231) — a time 2 seconds in the future.
+			future := time.Now().Add(2 * time.Second).UTC()
+			w.Header().Set("Retry-After", future.Format(http.TimeFormat))
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	start := time.Now()
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	elapsed := time.Since(start)
+
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(body) != `{"ok":true}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+	// HTTP-date was ~2s in the future; by the time client processes it,
+	// time.Until gives ~1-2s. Verify it's meaningfully delayed (not instant).
+	if elapsed < 500*time.Millisecond {
+		t.Errorf("expected meaningful delay from HTTP-date Retry-After, got %v", elapsed)
+	}
+}
+
+func TestDoRequest_429RetryAfterHTTPDateInPast(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			// Use a time in the past — should result in zero/immediate retry.
+			past := time.Now().Add(-10 * time.Second).UTC()
+			w.Header().Set("Retry-After", past.Format(http.TimeFormat))
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{5 * time.Second, 5 * time.Second}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	start := time.Now()
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	elapsed := time.Since(start)
+
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+	// Past date should override the 5s backoff to ~0
+	if elapsed > 500*time.Millisecond {
+		t.Errorf("expected near-instant retry for past HTTP-date, got %v", elapsed)
+	}
+}
+
+func TestDoRequest_SetsUserAgentHeader(t *testing.T) {
+	var gotUA string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotUA = r.Header.Get("User-Agent")
+		w.WriteHeader(200)
+		w.Write([]byte("{}"))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	_, _ = c.doGet(context.Background(), srv.URL+"/test")
+
+	if gotUA != "review-bot/1.0" {
+		t.Errorf("expected User-Agent 'review-bot/1.0', got %q", gotUA)
+	}
+}
+
+func TestDoRequest_LimitsResponseBody(t *testing.T) {
+	// Verify that oversized responses return an error rather than silently truncating.
+	bigBody := strings.Repeat("x", maxResponseBytes+1024)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(bigBody))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error for oversized response body")
+	}
+	if !strings.Contains(err.Error(), "exceeded") {
+		t.Errorf("expected truncation error, got: %v", err)
+	}
+}
+
+func TestDoRequest_AcceptsExactlyAtLimit(t *testing.T) {
+	// A response body exactly equal to maxResponseBytes should succeed (not error).
+	exactBody := strings.Repeat("x", maxResponseBytes)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(exactBody))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err != nil {
+		t.Fatalf("unexpected error for exactly-at-limit body: %v", err)
+	}
+	if len(body) != maxResponseBytes {
+		t.Errorf("expected body length %d, got %d", maxResponseBytes, len(body))
+	}
+}
+
+func TestDoRequest_SkipsAuthWhenTokenEmpty(t *testing.T) {
+	var gotAuth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAuth = r.Header.Get("Authorization")
+		w.WriteHeader(200)
+		w.Write([]byte("{}"))
+	}))
+	defer srv.Close()
+
+	c := NewClient("", srv.URL, AllowInsecureHTTP()) // empty token
+	c.SetHTTPClient(srv.Client())
+	_, _ = c.doGet(context.Background(), srv.URL+"/test")
+
+	if gotAuth != "" {
+		t.Errorf("expected no Authorization header with empty token, got %q", gotAuth)
+	}
+}
+
+func TestNewClient_CheckRedirectStripsAuthOnCrossHost(t *testing.T) {
+	// Verify the CheckRedirect function is configured
+	c := NewClient("secret-token", "https://api.github.com")
+	if c.httpClient.CheckRedirect == nil {
+		t.Fatal("expected CheckRedirect to be set")
+	}
+}
+
+func TestDefaultCheckRedirect_RejectsHTTPSToHTTP(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "api.github.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "http", Host: "api.github.com", Path: "/foo"},
+		Header: http.Header{"Authorization": []string{"Bearer token"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err == nil {
+		t.Fatal("expected error on HTTPS→HTTP redirect")
+	}
+	if !strings.Contains(err.Error(), "refusing redirect from HTTPS to HTTP") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDefaultCheckRedirect_StripsAuthOnCrossHost(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "api.github.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "https", Host: "objects.githubusercontent.com", Path: "/bar"},
+		Header: http.Header{"Authorization": []string{"Bearer token"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if auth := req.Header.Get("Authorization"); auth != "" {
+		t.Errorf("expected Authorization header to be stripped, got %q", auth)
+	}
+}
+
+func TestDefaultCheckRedirect_PreservesAuthOnSameHost(t *testing.T) {
+	prev := &http.Request{URL: &url.URL{Scheme: "https", Host: "api.github.com", Path: "/foo"}}
+	req := &http.Request{
+		URL:    &url.URL{Scheme: "https", Host: "api.github.com", Path: "/bar"},
+		Header: http.Header{"Authorization": []string{"Bearer token"}},
+	}
+	err := defaultCheckRedirect(req, []*http.Request{prev})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if auth := req.Header.Get("Authorization"); auth != "Bearer token" {
+		t.Errorf("expected Authorization to be preserved, got %q", auth)
+	}
+}
+
+func TestDoRequest_RejectsHTTPWithToken(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte("{}"))
+	}))
+	defer srv.Close()
+
+	// Without AllowInsecureHTTP, should refuse to send token over HTTP
+	c := NewClient("secret-token", srv.URL)
+	c.SetHTTPClient(srv.Client())
+	_, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err == nil {
+		t.Fatal("expected error when sending token over HTTP")
+	}
+	if !strings.Contains(err.Error(), "refusing to send credentials") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+}
+
+func TestDoRequest_AllowsHTTPWithoutToken(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	// Without token, HTTP should be fine (no credentials to leak)
+	c := NewClient("", srv.URL)
+	c.SetHTTPClient(srv.Client())
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(body) != `{"ok":true}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+}
+
+func TestDoRequest_AllowsHTTPWithInsecureOption(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`{"ok":true}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("secret-token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	body, err := c.doGet(context.Background(), srv.URL+"/test")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if string(body) != `{"ok":true}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+}
+
+func TestSetHTTPClient_NilRestoresDefault(t *testing.T) {
+	c := NewClient("token", "https://api.github.com")
+	c.SetHTTPClient(nil)
+	if c.httpClient == nil {
+		t.Fatal("expected non-nil httpClient after SetHTTPClient(nil)")
+	}
+	if c.httpClient.Timeout != 30*time.Second {
+		t.Errorf("expected 30s timeout, got %v", c.httpClient.Timeout)
+	}
+	if c.httpClient.CheckRedirect == nil {
+		t.Fatal("expected CheckRedirect policy after SetHTTPClient(nil)")
+	}
+}
+
+
+func TestSetRetryBackoff_RejectsInvalidLength(t *testing.T) {
+	c := NewClient("token", "https://api.github.com")
+
+	// Too short
+	err := c.SetRetryBackoff([]time.Duration{1 * time.Second})
+	if err == nil {
+		t.Fatal("expected error for backoff length 1")
+	}
+	if !strings.Contains(err.Error(), "backoff length 1") {
+		t.Errorf("unexpected error message: %v", err)
+	}
+
+	// Too long
+	err = c.SetRetryBackoff([]time.Duration{1 * time.Second, 2 * time.Second, 3 * time.Second})
+	if err == nil {
+		t.Fatal("expected error for backoff length 3")
+	}
+
+	// Correct length succeeds
+	err = c.SetRetryBackoff([]time.Duration{1 * time.Second, 2 * time.Second})
+	if err != nil {
+		t.Fatalf("unexpected error for valid backoff: %v", err)
+	}
+}
+
+func TestDoJSONRequest_429Retry(t *testing.T) {
+	attempts := 0
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts < 3 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit exceeded"}`))
+			return
+		}
+		w.WriteHeader(200)
+		w.Write([]byte(`{"id":1}`))
+	}))
+	defer ts.Close()
+
+	c := NewClient("token", ts.URL, AllowInsecureHTTP())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	body, err := c.doJSONRequest(context.Background(), http.MethodPost, ts.URL+"/test", map[string]string{"key": "val"})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if attempts != 3 {
+		t.Errorf("expected 3 attempts, got %d", attempts)
+	}
+	if string(body) != `{"id":1}` {
+		t.Errorf("unexpected body: %s", body)
+	}
+}
+
+func TestDoJSONRequest_429ExhaustsRetries(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(429)
+		w.Write([]byte(`{"message":"rate limit"}`))
+	}))
+	defer ts.Close()
+
+	c := NewClient("token", ts.URL, AllowInsecureHTTP())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	_, err := c.doJSONRequest(context.Background(), http.MethodPost, ts.URL+"/test", map[string]string{"key": "val"})
+	if err == nil {
+		t.Fatal("expected error after exhausting retries")
+	}
+	var apiErr *APIError
+	if !errors.As(err, &apiErr) {
+		t.Fatalf("expected APIError, got %T: %v", err, err)
+	}
+	if apiErr.StatusCode != 429 {
+		t.Errorf("expected 429, got %d", apiErr.StatusCode)
+	}
+}

github/conformance_test.go

@@ -0,0 +1,10 @@
+package github_test
+
+import (
+	"gitea.weiker.me/rodin/review-bot/github"
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+// Compile-time interface conformance assertions.
+// These verify github.Client satisfies vcs.Client (the full interface).
+var _ vcs.Client = (*github.Client)(nil)

github/files.go

@@ -0,0 +1,160 @@
+package github
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"net/url"
+	"path"
+	"strings"
+
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+// GetFileContent fetches a file from a repo at the given ref.
+// Delegates to GetFileContentAtRef with the provided ref.
+func (c *Client) GetFileContent(ctx context.Context, owner, repo, filePath, ref string) (string, error) {
+	return c.GetFileContentAtRef(ctx, owner, repo, filePath, ref)
+}
+
+// GetFileContentAtRef fetches a file at a specific ref from a repo.
+// If ref is empty, the query parameter is omitted (uses default branch).
+//
+// Returns an error if the path contains dot-segments (".", "..") or
+// attempts to traverse above the repository root.
+func (c *Client) GetFileContentAtRef(ctx context.Context, owner, repo, filePath, ref string) (string, error) {
+	escaped, err := escapePath(filePath)
+	if err != nil {
+		return "", fmt.Errorf("invalid file path: %w", err)
+	}
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escaped)
+	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 struct {
+		Content  string `json:"content"`
+		Encoding string `json:"encoding"`
+	}
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return "", fmt.Errorf("parse file content JSON: %w", err)
+	}
+	if resp.Encoding != "base64" {
+		return "", fmt.Errorf("unexpected encoding %q for file %s", resp.Encoding, filePath)
+	}
+	decoded, err := decodeBase64Content(resp.Content)
+	if err != nil {
+		return "", fmt.Errorf("decode base64 content for %s: %w", filePath, err)
+	}
+	return decoded, nil
+}
+
+// ListContents lists files and directories at a given path in a repo.
+// Returns the directory listing from the GitHub contents API.
+// If the path points to a single file (not a directory), the API returns
+// a JSON object instead of an array; this is handled by returning a
+// single-element slice.
+func (c *Client) ListContents(ctx context.Context, owner, repo, filePath string) ([]vcs.ContentEntry, error) {
+	escaped, err := escapePath(filePath)
+	if err != nil {
+		return nil, fmt.Errorf("invalid file path: %w", err)
+	}
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/contents/%s",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), escaped)
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("list contents %s: %w", filePath, err)
+	}
+
+	type entry struct {
+		Name string `json:"name"`
+		Path string `json:"path"`
+		Type string `json:"type"`
+	}
+
+	// The GitHub contents API returns an array for directories and an object
+	// for single files. Try array first (common case), then fall back to object.
+	// An empty array ([]) is valid — it represents an empty directory — and
+	// results in a zero-length slice returned without error.
+	var entries []entry
+	if err := json.Unmarshal(body, &entries); err != nil {
+		var single entry
+		if err2 := json.Unmarshal(body, &single); err2 != nil {
+			return nil, fmt.Errorf("parse contents JSON: as array: %v; as object: %w", err, err2)
+		}
+		// Guard against empty objects ({}) or unexpected shapes that
+		// unmarshal successfully but carry no useful data.
+		if single.Name == "" && single.Path == "" && single.Type == "" {
+			return nil, fmt.Errorf("parse contents JSON: unexpected response format")
+		}
+		entries = []entry{single}
+	}
+
+	result := make([]vcs.ContentEntry, len(entries))
+	for i, e := range entries {
+		result[i] = vcs.ContentEntry{
+			Name: e.Name,
+			Path: e.Path,
+			Type: e.Type,
+		}
+	}
+	return result, nil
+}
+
+// escapePath validates and encodes a slash-separated file path for use in
+// GitHub API URLs. Returns an error if the path contains dot-segments ("."
+// or "..") or resolves to a path outside the repository root.
+func escapePath(p string) (string, error) {
+	// Reject paths containing dot-segments rather than silently rewriting them.
+	for _, seg := range strings.Split(p, "/") {
+		if seg == "." || seg == ".." {
+			return "", fmt.Errorf("path contains dot-segment %q: %s", seg, p)
+		}
+	}
+
+	// Use path.Clean for canonical form, then verify it doesn't escape root.
+	cleaned := path.Clean(p)
+	if cleaned == "." || strings.HasPrefix(cleaned, "..") {
+		return "", fmt.Errorf("path resolves outside repository root: %s", p)
+	}
+
+	// Encode each segment individually.
+	parts := strings.Split(cleaned, "/")
+	var encoded []string
+	for _, part := range parts {
+		if part == "" {
+			continue
+		}
+		encoded = append(encoded, url.PathEscape(part))
+	}
+	return strings.Join(encoded, "/"), nil
+}
+
+// maxFileContentSize is the maximum decoded file size (10 MB) to prevent
+// resource exhaustion when decoding base64 content from the API.
+const maxFileContentSize = 10 * 1024 * 1024
+
+// decodeBase64Content decodes base64-encoded content from the GitHub contents API.
+// GitHub returns base64 content with line breaks for formatting; we strip \r and \n before decoding.
+// Returns an error if the decoded content exceeds maxFileContentSize.
+func decodeBase64Content(encoded string) (string, error) {
+	cleaned := strings.NewReplacer("\n", "", "\r", "").Replace(encoded)
+	// Check estimated decoded size before allocating.
+	// Base64 encodes 3 bytes into 4 chars, so decoded ~ len*3/4.
+	if len(cleaned)*3/4 > maxFileContentSize {
+		return "", fmt.Errorf("file content too large: estimated %d bytes exceeds limit of %d", len(cleaned)*3/4, maxFileContentSize)
+	}
+	decoded, err := base64.StdEncoding.DecodeString(cleaned)
+	if err != nil {
+		return "", err
+	}
+	if len(decoded) > maxFileContentSize {
+		return "", fmt.Errorf("file content too large: %d bytes exceeds limit of %d", len(decoded), maxFileContentSize)
+	}
+	return string(decoded), nil
+}

github/files_test.go

@@ -0,0 +1,405 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestGetFileContent_DelegatesToGetFileContentAtRef(t *testing.T) {
+	var gotRef string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotRef = r.URL.Query().Get("ref")
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "dGVzdA==", // "test" in base64
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	// Call with empty ref — should not include ref param
+	content, err := c.GetFileContent(context.Background(), "owner", "repo", "file.go", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "test" {
+		t.Errorf("expected 'test', got %q", content)
+	}
+	if gotRef != "" {
+		t.Errorf("expected empty ref, got %q", gotRef)
+	}
+}
+
+func TestGetFileContent_WithRef(t *testing.T) {
+	var gotRef string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotRef = r.URL.Query().Get("ref")
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "dGVzdA==",
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContent(context.Background(), "owner", "repo", "file.go", "abc123")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if gotRef != "abc123" {
+		t.Errorf("expected ref 'abc123', got %q", gotRef)
+	}
+}
+
+func TestGetFileContent_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContent(context.Background(), "owner", "repo", "missing.go", "")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestGetFileContent_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContent(context.Background(), "owner", "repo", "file.go", "")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+}
+
+func TestGetFileContent_429Retry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "b2s=",
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	content, err := c.GetFileContent(context.Background(), "owner", "repo", "file.go", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "ok" {
+		t.Errorf("expected 'ok', got %q", content)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+}
+
+func TestGetFileContent_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`not json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContent(context.Background(), "owner", "repo", "file.go", "")
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+}
+
+func TestListContents_HappyPath(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/repos/owner/repo/contents/src" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		json.NewEncoder(w).Encode([]map[string]string{
+			{"name": "main.go", "path": "src/main.go", "type": "file"},
+			{"name": "lib", "path": "src/lib", "type": "dir"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	entries, err := c.ListContents(context.Background(), "owner", "repo", "src")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 2 {
+		t.Fatalf("expected 2 entries, got %d", len(entries))
+	}
+	if entries[0].Name != "main.go" {
+		t.Errorf("expected name 'main.go', got %q", entries[0].Name)
+	}
+	if entries[0].Path != "src/main.go" {
+		t.Errorf("expected path 'src/main.go', got %q", entries[0].Path)
+	}
+	if entries[0].Type != "file" {
+		t.Errorf("expected type 'file', got %q", entries[0].Type)
+	}
+	if entries[1].Name != "lib" {
+		t.Errorf("expected name 'lib', got %q", entries[1].Name)
+	}
+	if entries[1].Type != "dir" {
+		t.Errorf("expected type 'dir', got %q", entries[1].Type)
+	}
+}
+
+func TestListContents_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.ListContents(context.Background(), "owner", "repo", "missing")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestListContents_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.ListContents(context.Background(), "owner", "repo", "src")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+}
+
+func TestListContents_429Retry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		json.NewEncoder(w).Encode([]map[string]string{
+			{"name": "file.go", "path": "file.go", "type": "file"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	if err := c.SetRetryBackoff([]time.Duration{1 * time.Millisecond, 1 * time.Millisecond}); err != nil {
+		t.Fatalf("SetRetryBackoff: %v", err)
+	}
+
+	entries, err := c.ListContents(context.Background(), "owner", "repo", "src")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(entries) != 1 {
+		t.Fatalf("expected 1 entry, got %d", len(entries))
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+}
+
+func TestListContents_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`not json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.ListContents(context.Background(), "owner", "repo", "src")
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+}
+
+func TestListContents_SingleFile(t *testing.T) {
+	// GitHub Contents API returns a JSON object (not array) for single-file paths
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`{"name":"README.md","path":"README.md","type":"file"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	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("expected 1 entry, got %d", len(entries))
+	}
+	if entries[0].Name != "README.md" {
+		t.Errorf("expected name 'README.md', got %q", entries[0].Name)
+	}
+	if entries[0].Type != "file" {
+		t.Errorf("expected type 'file', got %q", entries[0].Type)
+	}
+}
+
+func TestEscapePath_ValidPaths(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name string
+		path string
+		want string
+	}{
+		{"simple file", "file.go", "file.go"},
+		{"nested path", "path/to/file.go", "path/to/file.go"},
+		{"special chars", "path/to/my file.go", "path/to/my%20file.go"},
+		{"leading slash stripped", "/path/to/file.go", "path/to/file.go"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			got, err := escapePath(tt.path)
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if got != tt.want {
+				t.Errorf("escapePath(%q) = %q, want %q", tt.path, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestEscapePath_DotSegments(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name string
+		path string
+	}{
+		{"single dot", "./file.go"},
+		{"double dot", "../file.go"},
+		{"dot in middle", "path/./file.go"},
+		{"parent traversal", "path/../file.go"},
+		{"only dots", ".."},
+		{"nested parent traversal", "a/b/../../c"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			_, err := escapePath(tt.path)
+			if err == nil {
+				t.Fatalf("expected error for path %q, got nil", tt.path)
+			}
+			if !strings.Contains(err.Error(), "dot-segment") {
+				t.Errorf("expected error about dot-segment, got: %v", err)
+			}
+		})
+	}
+}
+
+func TestGetFileContentAtRef_DotSegmentError(t *testing.T) {
+	// Server should never be called — the error is caught before the request.
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		t.Fatal("server should not have been called")
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	_, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "foo/../bar.go", "main")
+	if err == nil {
+		t.Fatal("expected error for path with dot-segments")
+	}
+	if !strings.Contains(err.Error(), "invalid file path") {
+		t.Errorf("expected 'invalid file path' error, got: %v", err)
+	}
+}
+
+func TestDecodeBase64Content(t *testing.T) {
+	// Test with newlines (GitHub's format)
+	encoded := "cGFja2FnZSBt\nYWlu"
+	decoded, err := decodeBase64Content(encoded)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if decoded != "package main" {
+		t.Errorf("expected 'package main', got %q", decoded)
+	}
+}
+
+func TestDecodeBase64Content_Invalid(t *testing.T) {
+	_, err := decodeBase64Content("not!!!valid!!!base64")
+	if err == nil {
+		t.Fatal("expected error for invalid base64")
+	}
+}
+
+func TestDecodeBase64Content_CRLF(t *testing.T) {
+	// Base64 of "hello world" with CRLF line breaks inserted
+	encoded := "aGVs\r\nbG8g\r\nd29y\r\nbGQ="
+	decoded, err := decodeBase64Content(encoded)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if decoded != "hello world" {
+		t.Errorf("expected 'hello world', got %q", decoded)
+	}
+}
+
+func TestDecodeBase64Content_SizeLimit(t *testing.T) {
+	t.Parallel()
+	// Create base64 content that would decode to > maxFileContentSize.
+	// maxFileContentSize is 10MB. Base64 of 11MB worth of zeros.
+	// We just need something big enough to trigger the estimated size check.
+	// 14MB of base64 chars (decodes to ~10.5MB).
+	huge := strings.Repeat("A", 14*1024*1024)
+	_, err := decodeBase64Content(huge)
+	if err == nil {
+		t.Fatal("expected error for oversized content")
+	}
+	if !strings.Contains(err.Error(), "too large") {
+		t.Errorf("expected 'too large' error, got: %v", err)
+	}
+}

github/pr.go

@@ -0,0 +1,222 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+// pullRequestResponse is the GitHub API response for a pull request.
+type pullRequestResponse struct {
+	Number int    `json:"number"`
+	Title  string `json:"title"`
+	Body   string `json:"body"`
+	Head   struct {
+		SHA string `json:"sha"`
+		Ref string `json:"ref"`
+	} `json:"head"`
+	Base struct {
+		Ref string `json:"ref"`
+	} `json:"base"`
+}
+
+// changedFileResponse is the GitHub API response for a changed file in a PR.
+type changedFileResponse struct {
+	Filename string `json:"filename"`
+	Status   string `json:"status"`
+	Patch    string `json:"patch"`
+}
+
+// commitStatusResponse is the GitHub combined status API response.
+type commitStatusResponse struct {
+	Statuses []struct {
+		Context     string `json:"context"`
+		State       string `json:"state"`
+		Description string `json:"description"`
+		TargetURL   string `json:"target_url"`
+	} `json:"statuses"`
+}
+
+// checkRunsResponse is the GitHub check runs API response.
+type checkRunsResponse struct {
+	CheckRuns []struct {
+		Name       string  `json:"name"`
+		Conclusion *string `json:"conclusion"`
+		Status     string  `json:"status"`
+		HTMLURL    string  `json:"html_url"`
+	} `json:"check_runs"`
+}
+
+// GetPullRequest fetches PR metadata from the GitHub API.
+// Returns an *APIError wrapping the HTTP status on non-2xx responses (e.g.
+// IsNotFound for 404, IsUnauthorized for 401). Network and context errors
+// are wrapped but not typed as *APIError.
+func (c *Client) GetPullRequest(ctx context.Context, owner, repo string, number int) (*vcs.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 resp pullRequestResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return nil, fmt.Errorf("parse PR JSON: %w", err)
+	}
+	return &vcs.PullRequest{
+		Number: resp.Number,
+		Title:  resp.Title,
+		Body:   resp.Body,
+		Head:   vcs.HeadRef{SHA: resp.Head.SHA, Ref: resp.Head.Ref},
+		Base:   vcs.BaseRef{Ref: resp.Base.Ref},
+	}, nil
+}
+
+// GetPullRequestDiff fetches the unified diff for a PR.
+// Uses Accept: application/vnd.github.diff to get raw diff text.
+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
+}
+
+const (
+	// maxFilesPages is the upper bound on pagination loops for PR file listing,
+	// preventing unbounded iteration if the server always returns a full page.
+	maxFilesPages = 100
+
+	// maxCheckRunPages is the upper bound on pagination loops for check-run listing,
+	// preventing unbounded iteration if the server always returns a full page.
+	maxCheckRunPages = 100
+)
+
+// GetPullRequestFiles fetches the list of files changed in a PR.
+// Paginates through all pages (100 per page) to collect all files.
+// Returns nil (not an empty slice) when the PR has no changed files.
+// Callers can safely range over or check len() on a nil slice.
+func (c *Client) GetPullRequestFiles(ctx context.Context, owner, repo string, number int) ([]vcs.ChangedFile, error) {
+	var allFiles []vcs.ChangedFile
+
+	for page := 1; page <= maxFilesPages; page++ {
+		reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/files?per_page=100&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch PR files page %d: %w", page, err)
+		}
+		var files []changedFileResponse
+		if err := json.Unmarshal(body, &files); err != nil {
+			return nil, fmt.Errorf("parse PR files JSON: %w", err)
+		}
+		if len(files) == 0 {
+			break
+		}
+		for _, f := range files {
+			allFiles = append(allFiles, vcs.ChangedFile{
+				Filename: f.Filename,
+				Status:   f.Status,
+				Patch:    f.Patch,
+			})
+		}
+		if len(files) < 100 {
+			break
+		}
+	}
+
+	return allFiles, nil
+}
+
+// GetCommitStatuses fetches both commit statuses and check runs for a SHA,
+// merging them into a unified []vcs.CommitStatus slice.
+// Returns nil (not an empty slice) when there are no statuses or check runs.
+// If the commit statuses endpoint fails (e.g. 404 for an unknown SHA), the
+// function returns immediately without attempting the check-runs endpoint.
+// If the check-runs endpoint fails after statuses were fetched successfully,
+// the function returns an error (not a partial result) so callers always get
+// either a complete view or a clear error signal.
+func (c *Client) GetCommitStatuses(ctx context.Context, owner, repo, sha string) ([]vcs.CommitStatus, error) {
+	var result []vcs.CommitStatus
+
+	// Fetch commit statuses
+	statusURL := fmt.Sprintf("%s/repos/%s/%s/commits/%s/status",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), url.PathEscape(sha))
+	statusBody, err := c.doGet(ctx, statusURL)
+	if err != nil {
+		return nil, fmt.Errorf("fetch commit statuses: %w", err)
+	}
+	var statusResp commitStatusResponse
+	if err := json.Unmarshal(statusBody, &statusResp); err != nil {
+		return nil, fmt.Errorf("parse commit statuses JSON: %w", err)
+	}
+	for _, s := range statusResp.Statuses {
+		result = append(result, vcs.CommitStatus{
+			Context:     s.Context,
+			Status:      s.State,
+			Description: s.Description,
+			TargetURL:   s.TargetURL,
+		})
+	}
+
+	// Fetch check runs (paginated)
+	for checkPage := 1; checkPage <= maxCheckRunPages; checkPage++ {
+		checkURL := fmt.Sprintf("%s/repos/%s/%s/commits/%s/check-runs?per_page=100&page=%d",
+			c.baseURL, url.PathEscape(owner), url.PathEscape(repo), url.PathEscape(sha), checkPage)
+		checkBody, err := c.doGet(ctx, checkURL)
+		if err != nil {
+			return nil, fmt.Errorf("fetch check runs page %d: %w", checkPage, err)
+		}
+		var checkResp checkRunsResponse
+		if err := json.Unmarshal(checkBody, &checkResp); err != nil {
+			return nil, fmt.Errorf("parse check runs JSON: %w", err)
+		}
+		for _, cr := range checkResp.CheckRuns {
+			result = append(result, vcs.CommitStatus{
+				Context:     cr.Name,
+				Status:      mapCheckRunStatus(cr.Conclusion),
+				Description: "", // check runs have no human-readable description; conclusion is captured in Status
+				TargetURL:   cr.HTMLURL,
+			})
+		}
+		if len(checkResp.CheckRuns) < 100 {
+			break
+		}
+	}
+
+	return result, nil
+}
+
+// mapCheckRunStatus maps a GitHub check run conclusion to a vcs.CommitStatus status string.
+// Conclusion alone determines the mapped state: nil conclusion means the run is
+// still in progress (pending), regardless of the status field value.
+//
+// Mapping rules:
+//   - nil → "pending" (run still in progress or queued)
+//   - "success" → "success"
+//   - "failure", "action_required", "timed_out" → "failure"
+//   - "cancelled", "skipped", "neutral" → "success" (non-blocking per GitHub check suite semantics)
+//   - "stale" → "pending" (check run became stale before completing)
+//   - unknown values → "pending" (conservative: treat unrecognized conclusions as incomplete)
+func mapCheckRunStatus(conclusion *string) string {
+	if conclusion == nil {
+		// Still running or queued
+		return "pending"
+	}
+	switch *conclusion {
+	case "success":
+		return "success"
+	case "failure", "action_required", "timed_out":
+		return "failure"
+	case "cancelled", "skipped", "neutral":
+		return "success" // non-blocking: these do not indicate a blocking failure per GitHub check suite semantics
+	case "stale":
+		return "pending"
+	default:
+		return "pending"
+	}
+}
+

github/pr_test.go

@@ -0,0 +1,676 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestGetPullRequest_HappyPath(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)
+		}
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"number": 42,
+			"title":  "Test PR",
+			"body":   "Description",
+			"head":   map[string]string{"sha": "abc123", "ref": "feature-branch"},
+			"base":   map[string]string{"ref": "main"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	pr, err := c.GetPullRequest(context.Background(), "owner", "repo", 42)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if pr.Number != 42 {
+		t.Errorf("expected number 42, got %d", pr.Number)
+	}
+	if pr.Title != "Test PR" {
+		t.Errorf("expected title 'Test PR', got %q", pr.Title)
+	}
+	if pr.Body != "Description" {
+		t.Errorf("expected body 'Description', got %q", pr.Body)
+	}
+	if pr.Head.SHA != "abc123" {
+		t.Errorf("expected head SHA 'abc123', got %q", pr.Head.SHA)
+	}
+	if pr.Head.Ref != "feature-branch" {
+		t.Errorf("expected head ref 'feature-branch', got %q", pr.Head.Ref)
+	}
+	if pr.Base.Ref != "main" {
+		t.Errorf("expected base ref 'main', got %q", pr.Base.Ref)
+	}
+}
+
+func TestGetPullRequest_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequest(context.Background(), "owner", "repo", 999)
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+	if !IsNotFound(err) {
+		t.Errorf("expected IsNotFound=true, got error: %v", err)
+	}
+}
+
+func TestGetPullRequest_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequest(context.Background(), "owner", "repo", 1)
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got error: %v", err)
+	}
+}
+
+func TestGetPullRequest_429Retry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"number": 1,
+			"title":  "PR",
+			"body":   "",
+			"head":   map[string]string{"sha": "abc", "ref": "br"},
+			"base":   map[string]string{"ref": "main"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	c.SetRetryBackoff([]time.Duration{1 * time.Millisecond})
+
+	pr, err := c.GetPullRequest(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if pr.Number != 1 {
+		t.Errorf("expected number 1, got %d", pr.Number)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+}
+
+func TestGetPullRequest_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`{invalid json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequest(context.Background(), "owner", "repo", 1)
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+	if !strings.Contains(err.Error(), "parse PR JSON") {
+		t.Errorf("expected parse error, got: %v", err)
+	}
+}
+
+func TestGetPullRequestDiff_HappyPath(t *testing.T) {
+	expectedDiff := "diff --git a/file.go b/file.go\n--- a/file.go\n+++ b/file.go\n@@ -1,3 +1,4 @@\n+// new line\n"
+	var gotAccept string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAccept = r.Header.Get("Accept")
+		w.WriteHeader(200)
+		w.Write([]byte(expectedDiff))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	diff, err := c.GetPullRequestDiff(context.Background(), "owner", "repo", 42)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if diff != expectedDiff {
+		t.Errorf("unexpected diff: %q", diff)
+	}
+	if gotAccept != "application/vnd.github.diff" {
+		t.Errorf("expected diff Accept header, got %q", gotAccept)
+	}
+}
+
+func TestGetPullRequestDiff_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequestDiff(context.Background(), "owner", "repo", 999)
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestGetPullRequestDiff_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequestDiff(context.Background(), "owner", "repo", 1)
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+}
+
+func TestGetPullRequestFiles_HappyPath(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode([]map[string]interface{}{
+			{"filename": "main.go", "status": "modified", "patch": "@@ -1,3 +1,4 @@\n+line"},
+			{"filename": "test.go", "status": "added", "patch": "@@ -0,0 +1,5 @@\n+new file"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	files, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(files) != 2 {
+		t.Fatalf("expected 2 files, got %d", len(files))
+	}
+	if files[0].Filename != "main.go" {
+		t.Errorf("expected filename 'main.go', got %q", files[0].Filename)
+	}
+	if files[0].Status != "modified" {
+		t.Errorf("expected status 'modified', got %q", files[0].Status)
+	}
+	if files[0].Patch != "@@ -1,3 +1,4 @@\n+line" {
+		t.Errorf("unexpected patch: %q", files[0].Patch)
+	}
+}
+
+func TestGetPullRequestFiles_Pagination(t *testing.T) {
+	// Simulate > 100 files requiring pagination
+	page1Files := make([]map[string]string, 100)
+	for i := 0; i < 100; i++ {
+		page1Files[i] = map[string]string{
+			"filename": fmt.Sprintf("file%d.go", i),
+			"status":   "modified",
+			"patch":    fmt.Sprintf("patch%d", i),
+		}
+	}
+	page2Files := []map[string]string{
+		{"filename": "file100.go", "status": "added", "patch": "patch100"},
+	}
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		page := r.URL.Query().Get("page")
+		if page == "" || page == "1" {
+			json.NewEncoder(w).Encode(page1Files)
+		} else {
+			json.NewEncoder(w).Encode(page2Files)
+		}
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	files, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(files) != 101 {
+		t.Errorf("expected 101 files (paginated), got %d", len(files))
+	}
+	if files[100].Filename != "file100.go" {
+		t.Errorf("expected last file 'file100.go', got %q", files[100].Filename)
+	}
+	if files[100].Patch != "patch100" {
+		t.Errorf("expected last patch 'patch100', got %q", files[100].Patch)
+	}
+}
+
+func TestGetPullRequestFiles_BinaryFile_NoPatch(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Binary files have no patch field in GitHub response
+		json.NewEncoder(w).Encode([]map[string]interface{}{
+			{"filename": "image.png", "status": "added"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	files, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(files) != 1 {
+		t.Fatalf("expected 1 file, got %d", len(files))
+	}
+	if files[0].Patch != "" {
+		t.Errorf("expected empty patch for binary file, got %q", files[0].Patch)
+	}
+}
+
+func TestGetPullRequestFiles_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 999)
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestGetPullRequestFiles_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`not json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetPullRequestFiles(context.Background(), "owner", "repo", 1)
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+}
+
+func TestGetFileContentAtRef_HappyPath(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/repos/owner/repo/contents/path/to/file.go" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		if r.URL.Query().Get("ref") != "abc123" {
+			t.Errorf("unexpected ref: %s", r.URL.Query().Get("ref"))
+		}
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "cGFja2FnZSBtYWlu", // "package main" in base64
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	content, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "path/to/file.go", "abc123")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "package main" {
+		t.Errorf("expected 'package main', got %q", content)
+	}
+}
+
+func TestGetFileContentAtRef_EmptyRef(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Query().Get("ref") != "" {
+			t.Errorf("expected no ref param, got %q", r.URL.Query().Get("ref"))
+		}
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "aGVsbG8=", // "hello" in base64
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	content, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "file.txt", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "hello" {
+		t.Errorf("expected 'hello', got %q", content)
+	}
+}
+
+func TestGetFileContentAtRef_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "missing.go", "main")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestGetFileContentAtRef_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "file.go", "main")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+}
+
+func TestGetFileContentAtRef_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`not valid json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "file.go", "main")
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+}
+
+func TestGetFileContentAtRef_429Retry(t *testing.T) {
+	attempts := 0
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		attempts++
+		if attempts == 1 {
+			w.WriteHeader(429)
+			w.Write([]byte(`{"message":"rate limit"}`))
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]string{
+			"content":  "b2s=", // "ok" in base64
+			"encoding": "base64",
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+	c.SetRetryBackoff([]time.Duration{1 * time.Millisecond})
+
+	content, err := c.GetFileContentAtRef(context.Background(), "owner", "repo", "file.go", "main")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if content != "ok" {
+		t.Errorf("expected 'ok', got %q", content)
+	}
+	if attempts != 2 {
+		t.Errorf("expected 2 attempts, got %d", attempts)
+	}
+}
+
+func TestGetCommitStatuses_HappyPath(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case strings.Contains(r.URL.Path, "/status"):
+			json.NewEncoder(w).Encode(map[string]interface{}{
+				"state": "success",
+				"statuses": []map[string]string{
+					{
+						"context":     "ci/build",
+						"state":       "success",
+						"description": "Build passed",
+						"target_url":  "https://ci.example.com/1",
+					},
+				},
+			})
+		case strings.Contains(r.URL.Path, "/check-runs"):
+			conclusion := "success"
+			json.NewEncoder(w).Encode(map[string]interface{}{
+				"total_count": 1,
+				"check_runs": []map[string]interface{}{
+					{
+						"name":       "lint",
+						"conclusion": &conclusion,
+						"status":     "completed",
+						"html_url":   "https://github.com/check/1",
+					},
+				},
+			})
+		default:
+			t.Errorf("unexpected path: %s", r.URL.Path)
+			w.WriteHeader(404)
+		}
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	statuses, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "abc123")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(statuses) != 2 {
+		t.Fatalf("expected 2 statuses, got %d", len(statuses))
+	}
+	// First should be from commit statuses
+	if statuses[0].Context != "ci/build" {
+		t.Errorf("expected context 'ci/build', got %q", statuses[0].Context)
+	}
+	if statuses[0].Status != "success" {
+		t.Errorf("expected status 'success', got %q", statuses[0].Status)
+	}
+	// Second should be from check runs
+	if statuses[1].Context != "lint" {
+		t.Errorf("expected context 'lint', got %q", statuses[1].Context)
+	}
+	if statuses[1].Status != "success" {
+		t.Errorf("expected status 'success', got %q", statuses[1].Status)
+	}
+}
+
+func TestGetCommitStatuses_CheckRunConclusions(t *testing.T) {
+	tests := []struct {
+		conclusion *string
+		status     string
+		want       string
+	}{
+		{stringPtr("success"), "completed", "success"},
+		{stringPtr("failure"), "completed", "failure"},
+		{stringPtr("action_required"), "completed", "failure"},
+		{stringPtr("timed_out"), "completed", "failure"},
+		{stringPtr("cancelled"), "completed", "success"},
+		{stringPtr("skipped"), "completed", "success"},
+		{stringPtr("neutral"), "completed", "success"},
+		{nil, "in_progress", "pending"},
+		{nil, "queued", "pending"},
+	}
+
+	for _, tt := range tests {
+		name := "nil"
+		if tt.conclusion != nil {
+			name = *tt.conclusion
+		}
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				if strings.Contains(r.URL.Path, "/status") {
+					json.NewEncoder(w).Encode(map[string]interface{}{
+						"state":    "success",
+						"statuses": []interface{}{},
+					})
+					return
+				}
+				json.NewEncoder(w).Encode(map[string]interface{}{
+					"total_count": 1,
+					"check_runs": []map[string]interface{}{
+						{
+							"name":       "check",
+							"conclusion": tt.conclusion,
+							"status":     tt.status,
+							"html_url":   "https://github.com/check/1",
+						},
+					},
+				})
+			}))
+			defer srv.Close()
+
+			c := NewClient("token", srv.URL, AllowInsecureHTTP())
+			c.SetHTTPClient(srv.Client())
+
+			statuses, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "sha1")
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if len(statuses) != 1 {
+				t.Fatalf("expected 1 status, got %d", len(statuses))
+			}
+			if statuses[0].Status != tt.want {
+				t.Errorf("expected status %q, got %q", tt.want, statuses[0].Status)
+			}
+		})
+	}
+}
+
+func TestGetCommitStatuses_404(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "badsha")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+}
+
+func TestGetCommitStatuses_401(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "sha")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+}
+
+func TestGetCommitStatuses_MalformedJSON(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		w.Write([]byte(`not json`))
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "sha")
+	if err == nil {
+		t.Fatal("expected error for malformed JSON")
+	}
+}
+
+func TestGetCommitStatuses_CheckRunsErrorAfterStatusesSucceed(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case strings.Contains(r.URL.Path, "/status"):
+			// Statuses succeed
+			json.NewEncoder(w).Encode(map[string]interface{}{
+				"state": "success",
+				"statuses": []map[string]string{
+					{
+						"context":     "ci/build",
+						"state":       "success",
+						"description": "Build passed",
+						"target_url":  "https://ci.example.com/1",
+					},
+				},
+			})
+		case strings.Contains(r.URL.Path, "/check-runs"):
+			// Check runs fail with 500
+			w.WriteHeader(500)
+			w.Write([]byte(`{"message":"Internal Server Error"}`))
+		default:
+			w.WriteHeader(404)
+		}
+	}))
+	defer srv.Close()
+
+	c := NewClient("token", srv.URL, AllowInsecureHTTP())
+	c.SetHTTPClient(srv.Client())
+
+	_, err := c.GetCommitStatuses(context.Background(), "owner", "repo", "abc123")
+	if err == nil {
+		t.Fatal("expected error when check-runs endpoint fails after statuses succeed")
+	}
+	if !strings.Contains(err.Error(), "fetch check runs") {
+		t.Errorf("expected check runs error, got: %v", err)
+	}
+}
+
+func stringPtr(s string) *string {
+	return &s
+}

github/reviews.go

@@ -0,0 +1,198 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"net/url"
+
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+const (
+	// reviewsPerPage is the number of reviews to fetch per API page.
+	reviewsPerPage = 100
+	// maxReviewPages is the maximum number of pages to paginate through
+	// when listing reviews. Acts as a safeguard against infinite pagination.
+	maxReviewPages = 100
+)
+
+// reviewResponse is the GitHub API response for a pull request review.
+type reviewResponse struct {
+	ID   int64  `json:"id"`
+	Body string `json:"body"`
+	User struct {
+		Login string `json:"login"`
+	} `json:"user"`
+	State    string `json:"state"`
+	CommitID string `json:"commit_id"`
+}
+
+// reviewCreateRequest is the GitHub API request body for creating a pull request review.
+type reviewCreateRequest struct {
+	Body     string                `json:"body"`
+	Event    string                `json:"event"`
+	Comments []reviewCommentCreate `json:"comments,omitempty"`
+	CommitID string                `json:"commit_id,omitempty"`
+}
+
+// reviewCommentCreate is a single inline comment in a review creation request.
+type reviewCommentCreate struct {
+	Path     string `json:"path"`
+	Position int    `json:"position"`
+	Body     string `json:"body"`
+}
+
+// dismissReviewRequest is the GitHub API request body for dismissing a review.
+type dismissReviewRequest struct {
+	Message string `json:"message"`
+}
+
+// userResponse is the GitHub API response for the authenticated user.
+type userResponse struct {
+	Login string `json:"login"`
+}
+
+// translateReviewEvent converts a vcs.ReviewEvent to the GitHub API event string.
+func translateReviewEvent(event vcs.ReviewEvent) string {
+	switch event {
+	case vcs.ReviewEventApprove:
+		return "APPROVE"
+	case vcs.ReviewEventRequestChanges:
+		return "REQUEST_CHANGES"
+	default:
+		return "COMMENT"
+	}
+}
+
+// PostReview creates a new review on a pull request.
+func (c *Client) PostReview(ctx context.Context, owner, repo string, number int, req vcs.ReviewRequest) (*vcs.Review, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	payload := reviewCreateRequest{
+		Body:  req.Body,
+		Event: translateReviewEvent(req.Event),
+	}
+
+	for _, comment := range req.Comments {
+		rc := reviewCommentCreate{
+			Path:     comment.Path,
+			Position: comment.Position,
+			Body:     comment.Body,
+		}
+		payload.Comments = append(payload.Comments, rc)
+		// Use CommitID from the first comment that has one.
+		// All comments in a single review are expected to reference the same commit.
+		if payload.CommitID == "" && comment.CommitID != "" {
+			payload.CommitID = comment.CommitID
+		}
+	}
+
+	body, err := c.doJSONRequest(ctx, http.MethodPost, reqURL, payload)
+	if err != nil {
+		return nil, fmt.Errorf("post review: %w", err)
+	}
+
+	var resp reviewResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return nil, fmt.Errorf("parse review response: %w", err)
+	}
+
+	return &vcs.Review{
+		ID:       resp.ID,
+		Body:     resp.Body,
+		User:     vcs.UserInfo{Login: resp.User.Login},
+		State:    resp.State,
+		CommitID: resp.CommitID,
+	}, nil
+}
+
+// ListReviews lists all reviews on a pull request.
+func (c *Client) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcs.Review, error) {
+	var allReviews []vcs.Review
+
+	for page := 1; page <= maxReviewPages; 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, reviewsPerPage, page)
+		body, err := c.doGet(ctx, reqURL)
+		if err != nil {
+			return nil, fmt.Errorf("list reviews page %d: %w", page, err)
+		}
+		var reviews []reviewResponse
+		if err := json.Unmarshal(body, &reviews); err != nil {
+			return nil, fmt.Errorf("parse reviews JSON: %w", err)
+		}
+		if len(reviews) == 0 {
+			break
+		}
+		for _, r := range reviews {
+			allReviews = append(allReviews, vcs.Review{
+				ID:       r.ID,
+				Body:     r.Body,
+				User:     vcs.UserInfo{Login: r.User.Login},
+				State:    r.State,
+				CommitID: r.CommitID,
+			})
+		}
+		if len(reviews) < reviewsPerPage {
+			break
+		}
+		// NOTE: This warning only fires when the final page was full (the short-page
+		// break above did not trigger), meaning additional reviews likely exist beyond
+		// our page limit. The loop naturally exits after this iteration since page
+		// increments past maxReviewPages.
+		if page == maxReviewPages {
+			slog.Warn("ListReviews hit page limit; results may be truncated",
+				"owner", owner, "repo", repo, "pr", number,
+				"maxPages", maxReviewPages, "reviewsFetched", len(allReviews))
+		}
+	}
+
+	return allReviews, nil
+}
+
+// DeleteReview permanently deletes a review from a pull request.
+// Use DismissReview instead when the review should remain visible but marked as dismissed
+// (e.g., superseding an outdated review while preserving history).
+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)
+	_, err := c.doRequest(ctx, http.MethodDelete, reqURL, "")
+	if err != nil {
+		return fmt.Errorf("delete review: %w", err)
+	}
+	return nil
+}
+
+// DismissReview dismisses a review on a pull request with a message.
+func (c *Client) DismissReview(ctx context.Context, owner, repo string, number int, reviewID int64, message string) error {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews/%d/dismissals",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number, reviewID)
+
+	payload := dismissReviewRequest{
+		Message: message,
+	}
+
+	_, err := c.doJSONRequest(ctx, http.MethodPut, reqURL, payload)
+	if err != nil {
+		return fmt.Errorf("dismiss review: %w", err)
+	}
+	return nil
+}
+
+// GetAuthenticatedUser returns the login name of the authenticated user.
+func (c *Client) GetAuthenticatedUser(ctx context.Context) (string, error) {
+	reqURL := fmt.Sprintf("%s/user", c.baseURL)
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return "", fmt.Errorf("get authenticated user: %w", err)
+	}
+	var resp userResponse
+	if err := json.Unmarshal(body, &resp); err != nil {
+		return "", fmt.Errorf("parse user response: %w", err)
+	}
+	return resp.Login, nil
+}

review/formatter.go

@@ -10,18 +10,6 @@ func FormatMarkdown(result *ReviewResult, reviewerName string) string {
 	return FormatMarkdownWithDisplay(result, reviewerName, reviewerName)
 }
 
-// GiteaEvent converts the verdict to the Gitea API event string.
-func GiteaEvent(verdict string) string {
-	switch verdict {
-	case "APPROVE":
-		return "APPROVED"
-	case "REQUEST_CHANGES":
-		return "REQUEST_CHANGES"
-	default:
-		return "COMMENT"
-	}
-}
-
 // FormatMarkdownWithDisplay formats a ReviewResult with separate display name and sentinel name.
 // Note: displayName is not HTML-escaped as Gitea sanitizes rendered Markdown.
 // Persona display names are controlled by repo owners (trusted input).

review/formatter_test.go

@@ -98,25 +98,6 @@ func TestFormatMarkdown_SpecialChars(t *testing.T) {
 	}
 }
 
-func TestGiteaEvent(t *testing.T) {
-	tests := []struct {
-		verdict  string
-		expected string
-	}{
-		{"APPROVE", "APPROVED"},
-		{"REQUEST_CHANGES", "REQUEST_CHANGES"},
-		{"UNKNOWN", "COMMENT"},
-		{"", "COMMENT"},
-	}
-
-	for _, tc := range tests {
-		got := GiteaEvent(tc.verdict)
-		if got != tc.expected {
-			t.Errorf("GiteaEvent(%q) = %q, want %q", tc.verdict, got, tc.expected)
-		}
-	}
-}
-
 func TestFormatMarkdown_Sentinel(t *testing.T) {
 	result := &ReviewResult{
 		Verdict:        "APPROVE",

vcs/types.go

@@ -44,6 +44,7 @@ type PullRequest struct {
 type ChangedFile struct {
 	Filename string `json:"filename"`
 	Status   string `json:"status"`
+	Patch    string `json:"patch"`
 }
 
 // ContentEntry represents a file or directory entry from the contents API.