feat(agent-task/capi): add GetPullRequestDatabaseID method

Signed-off-by: Babak K. Shandiz <babakks@github.com>

pkg/cmd/agent-task/capi/sessions.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"github.com/cli/cli/v2/api"
+	"github.com/shurcooL/githubv4"
 	"github.com/vmihailenco/msgpack/v5"
 )
 
@@ -378,6 +379,34 @@ func (c *CAPIClient) hydrateSessionPullRequestsAndUsers(sessions []session) ([]*
 	return newSessions, nil
 }
 
+// GetPullRequestDatabaseID retrieves the database ID of a pull request given its number in a repository.
+func (c *CAPIClient) GetPullRequestDatabaseID(ctx context.Context, hostname string, owner string, repo string, number int) (int64, error) {
+	var resp struct {
+		Repository struct {
+			PullRequest struct {
+				FullDatabaseID string `graphql:"fullDatabaseId"`
+			} `graphql:"pullRequest(number: $number)"`
+		} `graphql:"repository(owner: $owner, name: $repo)"`
+	}
+
+	variables := map[string]interface{}{
+		"owner":  githubv4.String(owner),
+		"repo":   githubv4.String(repo),
+		"number": githubv4.Int(number),
+	}
+
+	apiClient := api.NewClientFromHTTP(c.httpClient)
+	if err := apiClient.Query(hostname, "GetPullRequestFullDatabaseID", &resp, variables); err != nil {
+		return 0, err
+	}
+
+	databaseID, err := strconv.ParseInt(resp.Repository.PullRequest.FullDatabaseID, 10, 64)
+	if err != nil {
+		return 0, err
+	}
+	return databaseID, nil
+}
+
 // generatePullRequestNodeID converts an int64 databaseID and repoID to a GraphQL Node ID format
 // with the "PR_" prefix for pull requests
 func generatePullRequestNodeID(repoID, pullRequestID int64) string {