Add --base to agentpr pr edit to retarget a PR

internal/agent/client_test.go

@@ -102,7 +102,7 @@ func TestCreatePRRequestBody(t *testing.T) {
 // An edit must send only the fields it was given: Gitea overwrites whatever
 // key it receives, so an omitted --title arriving as "" would blank the title.
 func TestEditPRSendsOnlySuppliedFields(t *testing.T) {
-	title, body, empty := "new title", "new body", ""
+	title, body, base, empty := "new title", "new body", "benvin/parent", ""
 	tests := []struct {
 		name string
 		opts EditOptions
@@ -112,6 +112,8 @@ func TestEditPRSendsOnlySuppliedFields(t *testing.T) {
 		{"title only", EditOptions{Title: &title}, map[string]any{"title": "new title"}},
 		{"both", EditOptions{Title: &title, Body: &body}, map[string]any{"title": "new title", "body": "new body"}},
 		{"explicit empty body is sent", EditOptions{Body: &empty}, map[string]any{"body": ""}},
+		{"base only", EditOptions{Base: &base}, map[string]any{"base": "benvin/parent"}},
+		{"base with title", EditOptions{Title: &title, Base: &base}, map[string]any{"title": "new title", "base": "benvin/parent"}},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {

internal/agent/gitea.go

@@ -283,13 +283,15 @@ func (c *GiteaClient) CreatePR(repoPath string, opts CreatePROptions) (PullReque
 // entirely, leaving that field as it is. The two fields are not symmetric:
 // Gitea only applies a title when it is non-empty, so Title can be set but
 // never cleared and a "" title is a silent no-op, while a pointer to "" Body
-// really does blank the body.
+// really does blank the body. Base retargets a pull request and is never set
+// for an issue.
 type EditOptions struct {
 	Title *string `json:"title,omitempty"`
 	Body  *string `json:"body,omitempty"`
+	Base  *string `json:"base,omitempty"`
 }
 
-// EditPR updates a pull request's title and/or body
+// EditPR updates a pull request's title, body and/or base branch
 // (PATCH /api/v1/repos/{owner}/{repo}/pulls/{index}).
 func (c *GiteaClient) EditPR(repoPath string, number int, opts EditOptions) (PullRequest, error) {
 	var pr PullRequest