# DEVX-169: create_dependency_pr uses branches API

## Problem

After DEVX-168, dep-PR creation fails at `POST /git/refs` with
`HTTP 405 Method Not Allowed` — this Gitea version does not implement the
createRef endpoint. Observed creating the sso_bridge 0.4.1 infra
dependency PR.

## Approach

REQ-1: Create the dependency branch via `POST /branches` with
`new_branch_name`/`old_branch_name` (from master). An already-exists
error is tolerated; other API errors fail closed.

## Test Plan

- Branch creation calls `POST /branches` with the expected payload.
- 422 already-exists is tolerated and the PR is still created.
- Other API errors abort with a branch-creation failure.

## Deploy Plan

devx release tag; producers pick it up via pin bumps.

## Rollback Plan

Revert; dep-PR creation stays broken (status quo).

## Acceptance Criteria

- [x] REQ-1: branch creation uses the branches API; already-exists
  tolerated; failures surface. Covered by unit tests at 100% coverage.