add reviewer assigning

cache.go

@@ -164,6 +164,19 @@ func (c *CachedGitHubService) UpdatePullRequest(
 	return writer.UpdatePullRequest(ctx, pullRequestID, update)
 }
 
+func (c *CachedGitHubService) UpdatePullRequestPeople(
+	ctx context.Context,
+	owner, repo string,
+	number int,
+	update PullRequestPeopleUpdate,
+) (PullRequestPeople, error) {
+	writer, ok := c.remote.(GitHubPullRequestPeopleWriteService)
+	if !ok {
+		return PullRequestPeople{}, errors.New("GitHub service does not support updating pull request people")
+	}
+	return writer.UpdatePullRequestPeople(ctx, owner, repo, number, update)
+}
+
 func (c *CachedGitHubService) SetPullRequestAutoMerge(
 	ctx context.Context, pullRequestID, expectedHeadOID, mergeMethod string, enabled bool,
 ) (*AutoMergeRequest, error) {
@@ -209,6 +222,29 @@ func (c *CachedGitHubService) ListBranches(
 	return nil, err
 }
 
+func (c *CachedGitHubService) ListRepositoryUsers(
+	ctx context.Context, owner, repo string,
+) ([]RepositoryUser, error) {
+	service, ok := c.remote.(GitHubRepositoryPeopleService)
+	if !ok {
+		return nil, errors.New("GitHub service does not support listing repository users")
+	}
+	users, err := service.ListRepositoryUsers(ctx, owner, repo)
+	if err == nil {
+		_ = c.write(c.repositoryUsersKey(owner, repo), users)
+		return users, nil
+	}
+	var cached cacheEnvelope[[]RepositoryUser]
+	if _, cacheErr := c.read(c.repositoryUsersKey(owner, repo), &cached); cacheErr == nil {
+		c.health.set(HealthComponent{
+			Name: "repository user cache", Level: healthWarning,
+			Summary: "using cached repository users", Detail: err.Error(), UpdatedAt: time.Now(),
+		})
+		return cached.Value, nil
+	}
+	return nil, err
+}
+
 func (c *CachedGitHubService) EnrichPullRequest(
 	ctx context.Context, details PRDetails,
 ) PRDetailsEnrichment {
@@ -238,6 +274,10 @@ func (c *CachedGitHubService) branchesKey(owner, repo string) string {
 	return fmt.Sprintf("branches:%s/%s", owner, repo)
 }
 
+func (c *CachedGitHubService) repositoryUsersKey(owner, repo string) string {
+	return fmt.Sprintf("repository-users:%s/%s", owner, repo)
+}
+
 func (c *CachedGitHubService) file(key string) string {
 	sum := sha256.Sum256([]byte(key))
 	return filepath.Join(c.dir, hex.EncodeToString(sum[:])+".json")