feat(github): implement Reviewer and Identity interfaces (#81)

Implement the remaining vcs.Client interface methods for github.Client:

Reviewer:
- PostReview: POST /repos/{owner}/{repo}/pulls/{number}/reviews
- ListReviews: GET /repos/{owner}/{repo}/pulls/{number}/reviews
  with state translation (CHANGES_REQUESTED → REQUEST_CHANGES, etc.)
- DeleteReview: DELETE /repos/{owner}/{repo}/pulls/{number}/reviews/{id}
  Returns ErrCannotDeleteSubmittedReview on 422
- DismissReview: PUT /repos/{owner}/{repo}/pulls/{number}/reviews/{id}/dismissals

Identity:
- GetAuthenticatedUser: GET /user

Infrastructure:
- Add doRequestWithBody helper for POST/PUT/DELETE with JSON bodies
- Update conformance_test.go: var _ vcs.Client = (*github.Client)(nil)

All unit tests pass including error cases (401, 404, 422, malformed).

github/client.go

@@ -4,6 +4,7 @@
 package github
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -342,3 +343,113 @@ func (c *Client) handleResponse(resp *http.Response, maxRespBytes int, maxErrByt
 func (c *Client) doGet(ctx context.Context, reqURL string) ([]byte, error) {
 	return c.doRequest(ctx, http.MethodGet, reqURL, "")
 }
+
+// doRequestWithBody is like doRequest but sends a request body.
+// It accepts the raw body bytes and sets Content-Type to application/json.
+// Retry semantics match doRequest (retries on 429 with Retry-After support).
+func (c *Client) doRequestWithBody(ctx context.Context, method, reqURL string, body []byte) ([]byte, error) {
+	const maxRetryAfter = 120 * time.Second
+
+	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)
+	}
+
+	const maxErrorBodyBytes = 4 * 1024
+
+	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()
+				case <-ctx.Done():
+					timer.Stop()
+					return nil, ctx.Err()
+				}
+			}
+		}
+
+		var bodyReader io.Reader
+		if body != nil {
+			bodyReader = bytes.NewReader(body)
+		}
+		req, err := http.NewRequestWithContext(ctx, method, reqURL, bodyReader)
+		if err != nil {
+			return nil, fmt.Errorf("create request: %w", 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")
+		if body != nil {
+			req.Header.Set("Content-Type", "application/json")
+		}
+
+		resp, err := c.httpClient.Do(req)
+		if err != nil {
+			return nil, fmt.Errorf("do request: %w", err)
+		}
+
+		respStatus := resp.StatusCode
+		retryAfterHeader := resp.Header.Get("Retry-After")
+
+		respBody, done, handleErr := c.handleResponse(resp, maxResponseBytes, maxErrorBodyBytes)
+		if done {
+			return respBody, handleErr
+		}
+		lastErr = handleErr
+
+		if respStatus == http.StatusTooManyRequests && attempt < maxRetryAttempts-1 {
+			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
+		}
+
+		return nil, lastErr
+	}
+
+	return nil, lastErr
+}

github/conformance_test.go

@@ -5,9 +5,7 @@ import (
 	"gitea.weiker.me/rodin/review-bot/vcs"
 )
 
-// Compile-time interface conformance assertions.
+// Compile-time interface conformance assertion.
-// These verify github.Client satisfies vcs.PRReader and vcs.FileReader.
+// This verifies github.Client satisfies the full vcs.Client interface
-var (
+// (PRReader, FileReader, Reviewer, Identity).
-	_ vcs.PRReader   = (*github.Client)(nil)
+var _ vcs.Client = (*github.Client)(nil)
-	_ vcs.FileReader = (*github.Client)(nil)
-)

github/identity.go

@@ -0,0 +1,29 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+)
+
+// userResponse is the GitHub API response for the authenticated user.
+type userResponse struct {
+	Login string `json:"login"`
+}
+
+// GetAuthenticatedUser returns the login of the currently 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
+}

github/identity_test.go

@@ -0,0 +1,46 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"testing"
+)
+
+func TestGetAuthenticatedUser_HappyPath(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "GET" {
+			t.Errorf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/user" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		if r.Header.Get("Authorization") != "Bearer test-token" {
+			t.Errorf("unexpected auth header: %s", r.Header.Get("Authorization"))
+		}
+		json.NewEncoder(w).Encode(map[string]string{"login": "review-bot"})
+	})
+
+	login, err := c.GetAuthenticatedUser(context.Background())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if login != "review-bot" {
+		t.Errorf("expected login 'review-bot', got %q", login)
+	}
+}
+
+func TestGetAuthenticatedUser_401(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	})
+
+	_, err := c.GetAuthenticatedUser(context.Background())
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got error: %v", err)
+	}
+}

github/review.go

@@ -0,0 +1,191 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/url"
+
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+// ErrCannotDeleteSubmittedReview is returned when DeleteReview is called on
+// a review that has already been submitted (APPROVED, REQUEST_CHANGES, COMMENT).
+// GitHub only allows deletion of PENDING reviews. Callers that need to replace
+// a submitted review should use DismissReview instead.
+var ErrCannotDeleteSubmittedReview = errors.New("cannot delete submitted review: use DismissReview instead")
+
+// postReviewRequest is the GitHub API request body for creating a review.
+type postReviewRequest struct {
+	CommitID string               `json:"commit_id,omitempty"`
+	Body     string               `json:"body"`
+	Event    string               `json:"event"`
+	Comments []reviewCommentEntry `json:"comments,omitempty"`
+}
+
+// reviewCommentEntry is a single inline comment in a review creation request.
+type reviewCommentEntry struct {
+	Path     string `json:"path"`
+	Position int    `json:"position"`
+	Body     string `json:"body"`
+}
+
+// reviewResponse is the GitHub API response for a review.
+type reviewResponse struct {
+	ID       int64  `json:"id"`
+	Body     string `json:"body"`
+	State    string `json:"state"`
+	CommitID string `json:"commit_id"`
+	User     struct {
+		Login string `json:"login"`
+	} `json:"user"`
+}
+
+// dismissReviewRequest is the GitHub API request body for dismissing a review.
+type dismissReviewRequest struct {
+	Message string `json:"message"`
+	Event   string `json:"event"`
+}
+
+// translateGitHubReviewState translates a GitHub API review state to the
+// canonical vcs.Review.State value.
+func translateGitHubReviewState(state string) string {
+	switch state {
+	case "APPROVED":
+		return "APPROVED"
+	case "CHANGES_REQUESTED":
+		return "REQUEST_CHANGES"
+	case "COMMENTED":
+		return "COMMENT"
+	case "DISMISSED":
+		return "DISMISSED"
+	default:
+		return state
+	}
+}
+
+// PostReview submits a review on a pull request.
+// The ReviewRequest.Event values (APPROVE, REQUEST_CHANGES, COMMENT) are sent
+// directly — they match GitHub's canonical event strings.
+// ReviewComment.Position maps directly to the GitHub API position field.
+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 := postReviewRequest{
+		Body:  req.Body,
+		Event: string(req.Event),
+	}
+
+	// Populate CommitID from the first comment if available.
+	// All comments in a single review share the same commit_id.
+	for _, comment := range req.Comments {
+		if comment.CommitID != "" {
+			payload.CommitID = comment.CommitID
+			break
+		}
+	}
+
+	for _, comment := range req.Comments {
+		payload.Comments = append(payload.Comments, reviewCommentEntry{
+			Path:     comment.Path,
+			Position: comment.Position,
+			Body:     comment.Body,
+		})
+	}
+
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return nil, fmt.Errorf("marshal review request: %w", err)
+	}
+
+	body, err := c.doRequestWithBody(ctx, "POST", reqURL, data)
+	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:    translateGitHubReviewState(resp.State),
+		CommitID: resp.CommitID,
+	}, nil
+}
+
+// ListReviews retrieves all reviews for a pull request.
+// GitHub review states are translated to canonical vcs values.
+func (c *Client) ListReviews(ctx context.Context, owner, repo string, number int) ([]vcs.Review, error) {
+	reqURL := fmt.Sprintf("%s/repos/%s/%s/pulls/%d/reviews",
+		c.baseURL, url.PathEscape(owner), url.PathEscape(repo), number)
+
+	body, err := c.doGet(ctx, reqURL)
+	if err != nil {
+		return nil, fmt.Errorf("list reviews: %w", err)
+	}
+
+	var responses []reviewResponse
+	if err := json.Unmarshal(body, &responses); err != nil {
+		return nil, fmt.Errorf("parse reviews response: %w", err)
+	}
+
+	reviews := make([]vcs.Review, len(responses))
+	for i, r := range responses {
+		reviews[i] = vcs.Review{
+			ID:       r.ID,
+			Body:     r.Body,
+			User:     vcs.UserInfo{Login: r.User.Login},
+			State:    translateGitHubReviewState(r.State),
+			CommitID: r.CommitID,
+		}
+	}
+	return reviews, nil
+}
+
+// DeleteReview deletes a pull request review.
+// Only PENDING reviews can be deleted; attempting to delete a submitted review
+// (APPROVED, CHANGES_REQUESTED, COMMENTED) returns ErrCannotDeleteSubmittedReview.
+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.doRequestWithBody(ctx, "DELETE", reqURL, nil)
+	if err != nil {
+		var apiErr *APIError
+		if errors.As(err, &apiErr) && apiErr.StatusCode == 422 {
+			return ErrCannotDeleteSubmittedReview
+		}
+		return fmt.Errorf("delete review: %w", err)
+	}
+	return nil
+}
+
+// DismissReview dismisses a submitted review on a pull request.
+// This is the correct way to "remove" a submitted review (APPROVED, REQUEST_CHANGES).
+// GitHub does not allow deleting submitted reviews — they must be dismissed.
+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,
+		Event:   "DISMISS",
+	}
+
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("marshal dismiss request: %w", err)
+	}
+
+	_, err = c.doRequestWithBody(ctx, "PUT", reqURL, data)
+	if err != nil {
+		return fmt.Errorf("dismiss review: %w", err)
+	}
+	return nil
+}

github/review_test.go

@@ -0,0 +1,394 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"gitea.weiker.me/rodin/review-bot/vcs"
+)
+
+func newTestClient(t *testing.T, handler http.HandlerFunc) *Client {
+	t.Helper()
+	srv := httptest.NewServer(handler)
+	t.Cleanup(srv.Close)
+	c := NewClient("test-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)
+	}
+	return c
+}
+
+// --- PostReview tests ---
+
+func TestPostReview_HappyPath(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			t.Errorf("expected POST, got %s", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/5/reviews" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		if r.Header.Get("Content-Type") != "application/json" {
+			t.Errorf("expected Content-Type application/json, got %q", r.Header.Get("Content-Type"))
+		}
+
+		// Verify request body
+		body, _ := io.ReadAll(r.Body)
+		var req postReviewRequest
+		if err := json.Unmarshal(body, &req); err != nil {
+			t.Fatalf("unmarshal request: %v", err)
+		}
+		if req.Event != "APPROVE" {
+			t.Errorf("expected event APPROVE, got %q", req.Event)
+		}
+		if req.Body != "LGTM" {
+			t.Errorf("expected body 'LGTM', got %q", req.Body)
+		}
+		if req.CommitID != "abc123" {
+			t.Errorf("expected commit_id 'abc123', got %q", req.CommitID)
+		}
+		if len(req.Comments) != 1 {
+			t.Fatalf("expected 1 comment, got %d", len(req.Comments))
+		}
+		if req.Comments[0].Path != "main.go" {
+			t.Errorf("expected comment path 'main.go', got %q", req.Comments[0].Path)
+		}
+		if req.Comments[0].Position != 4 {
+			t.Errorf("expected comment position 4, got %d", req.Comments[0].Position)
+		}
+
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"id":        100,
+			"body":      "LGTM",
+			"state":     "APPROVED",
+			"commit_id": "abc123",
+			"user":      map[string]string{"login": "reviewer"},
+		})
+	})
+
+	review, err := c.PostReview(context.Background(), "owner", "repo", 5, vcs.ReviewRequest{
+		Body:  "LGTM",
+		Event: vcs.ReviewEventApprove,
+		Comments: []vcs.ReviewComment{
+			{Path: "main.go", Position: 4, CommitID: "abc123", Body: "nit: rename"},
+		},
+	})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if review.ID != 100 {
+		t.Errorf("expected ID 100, got %d", review.ID)
+	}
+	if review.Body != "LGTM" {
+		t.Errorf("expected body 'LGTM', got %q", review.Body)
+	}
+	if review.State != "APPROVED" {
+		t.Errorf("expected state 'APPROVED', got %q", review.State)
+	}
+	if review.User.Login != "reviewer" {
+		t.Errorf("expected user 'reviewer', got %q", review.User.Login)
+	}
+	if review.CommitID != "abc123" {
+		t.Errorf("expected commit_id 'abc123', got %q", review.CommitID)
+	}
+}
+
+func TestPostReview_401(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	})
+
+	_, err := c.PostReview(context.Background(), "owner", "repo", 5, vcs.ReviewRequest{
+		Body:  "LGTM",
+		Event: vcs.ReviewEventApprove,
+	})
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got error: %v", err)
+	}
+}
+
+func TestPostReview_422(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(422)
+		w.Write([]byte(`{"message":"Unprocessable Entity"}`))
+	})
+
+	_, err := c.PostReview(context.Background(), "owner", "repo", 5, vcs.ReviewRequest{
+		Body:  "LGTM",
+		Event: vcs.ReviewEventApprove,
+	})
+	if err == nil {
+		t.Fatal("expected error for 422")
+	}
+	// 422 should surface as a wrapped APIError
+	var apiErr *APIError
+	if !errors.As(err, &apiErr) {
+		t.Fatalf("expected *APIError, got %T: %v", err, err)
+	}
+	if apiErr.StatusCode != 422 {
+		t.Errorf("expected status 422, got %d", apiErr.StatusCode)
+	}
+}
+
+func TestPostReview_MalformedResponse(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.Write([]byte(`not json`))
+	})
+
+	_, err := c.PostReview(context.Background(), "owner", "repo", 5, vcs.ReviewRequest{
+		Body:  "LGTM",
+		Event: vcs.ReviewEventApprove,
+	})
+	if err == nil {
+		t.Fatal("expected error for malformed response")
+	}
+	if !containsStr(err.Error(), "parse review response") {
+		t.Errorf("expected parse error, got: %v", err)
+	}
+}
+
+// --- ListReviews tests ---
+
+func TestListReviews_HappyPath(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "GET" {
+			t.Errorf("expected GET, got %s", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/3/reviews" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		json.NewEncoder(w).Encode([]map[string]interface{}{
+			{
+				"id":        1,
+				"body":      "Approved",
+				"state":     "APPROVED",
+				"commit_id": "sha1",
+				"user":      map[string]string{"login": "user1"},
+			},
+			{
+				"id":        2,
+				"body":      "Needs work",
+				"state":     "CHANGES_REQUESTED",
+				"commit_id": "sha2",
+				"user":      map[string]string{"login": "user2"},
+			},
+			{
+				"id":        3,
+				"body":      "Comment only",
+				"state":     "COMMENTED",
+				"commit_id": "sha3",
+				"user":      map[string]string{"login": "user3"},
+			},
+			{
+				"id":        4,
+				"body":      "Old review",
+				"state":     "DISMISSED",
+				"commit_id": "sha4",
+				"user":      map[string]string{"login": "user4"},
+			},
+		})
+	})
+
+	reviews, err := c.ListReviews(context.Background(), "owner", "repo", 3)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(reviews) != 4 {
+		t.Fatalf("expected 4 reviews, got %d", len(reviews))
+	}
+
+	// Check state translation
+	expected := []struct {
+		id    int64
+		state string
+	}{
+		{1, "APPROVED"},
+		{2, "REQUEST_CHANGES"},
+		{3, "COMMENT"},
+		{4, "DISMISSED"},
+	}
+	for i, e := range expected {
+		if reviews[i].ID != e.id {
+			t.Errorf("review[%d]: expected ID %d, got %d", i, e.id, reviews[i].ID)
+		}
+		if reviews[i].State != e.state {
+			t.Errorf("review[%d]: expected state %q, got %q", i, e.state, reviews[i].State)
+		}
+	}
+}
+
+func TestListReviews_404(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	})
+
+	_, err := c.ListReviews(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 TestListReviews_401(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	})
+
+	_, err := c.ListReviews(context.Background(), "owner", "repo", 3)
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got error: %v", err)
+	}
+}
+
+// --- DeleteReview tests ---
+
+func TestDeleteReview_HappyPath(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "DELETE" {
+			t.Errorf("expected DELETE, got %s", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/5/reviews/42" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+		w.WriteHeader(204)
+	})
+
+	err := c.DeleteReview(context.Background(), "owner", "repo", 5, 42)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestDeleteReview_422_SubmittedReview(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(422)
+		w.Write([]byte(`{"message":"Can not delete a non pending review"}`))
+	})
+
+	err := c.DeleteReview(context.Background(), "owner", "repo", 5, 42)
+	if err == nil {
+		t.Fatal("expected error for 422")
+	}
+	if !errors.Is(err, ErrCannotDeleteSubmittedReview) {
+		t.Errorf("expected ErrCannotDeleteSubmittedReview, got: %v", err)
+	}
+}
+
+// --- DismissReview tests ---
+
+func TestDismissReview_HappyPath(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "PUT" {
+			t.Errorf("expected PUT, got %s", r.Method)
+		}
+		if r.URL.Path != "/repos/owner/repo/pulls/5/reviews/10/dismissals" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+		}
+
+		body, _ := io.ReadAll(r.Body)
+		var req dismissReviewRequest
+		if err := json.Unmarshal(body, &req); err != nil {
+			t.Fatalf("unmarshal request: %v", err)
+		}
+		if req.Message != "Superseded by new review" {
+			t.Errorf("expected message 'Superseded by new review', got %q", req.Message)
+		}
+		if req.Event != "DISMISS" {
+			t.Errorf("expected event 'DISMISS', got %q", req.Event)
+		}
+
+		json.NewEncoder(w).Encode(map[string]interface{}{
+			"id":    10,
+			"state": "DISMISSED",
+		})
+	})
+
+	err := c.DismissReview(context.Background(), "owner", "repo", 5, 10, "Superseded by new review")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
+
+func TestDismissReview_404(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(404)
+		w.Write([]byte(`{"message":"Not Found"}`))
+	})
+
+	err := c.DismissReview(context.Background(), "owner", "repo", 5, 999, "dismiss")
+	if err == nil {
+		t.Fatal("expected error for 404")
+	}
+	if !IsNotFound(err) {
+		t.Errorf("expected IsNotFound=true, got error: %v", err)
+	}
+}
+
+func TestDismissReview_401(t *testing.T) {
+	c := newTestClient(t, func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(401)
+		w.Write([]byte(`{"message":"Bad credentials"}`))
+	})
+
+	err := c.DismissReview(context.Background(), "owner", "repo", 5, 10, "dismiss")
+	if err == nil {
+		t.Fatal("expected error for 401")
+	}
+	if !IsUnauthorized(err) {
+		t.Errorf("expected IsUnauthorized=true, got error: %v", err)
+	}
+}
+
+// --- State translation tests ---
+
+func TestTranslateGitHubReviewState(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"APPROVED", "APPROVED"},
+		{"CHANGES_REQUESTED", "REQUEST_CHANGES"},
+		{"COMMENTED", "COMMENT"},
+		{"DISMISSED", "DISMISSED"},
+		{"UNKNOWN_STATE", "UNKNOWN_STATE"},
+		{"", ""},
+	}
+	for _, tt := range tests {
+		got := translateGitHubReviewState(tt.input)
+		if got != tt.expected {
+			t.Errorf("translateGitHubReviewState(%q) = %q, want %q", tt.input, got, tt.expected)
+		}
+	}
+}
+
+// containsStr is a test helper for checking error messages.
+func containsStr(s, substr string) bool {
+	return len(s) >= len(substr) && (s == substr || len(s) > 0 && containsSubstring(s, substr))
+}
+
+func containsSubstring(s, sub string) bool {
+	for i := 0; i <= len(s)-len(sub); i++ {
+		if s[i:i+len(sub)] == sub {
+			return true
+		}
+	}
+	return false
+}