Worked on the anthropics/claude-code-action repository to address a reliability issue affecting prompt isolation on non-ephemeral self-hosted runners. Using Node.js and TypeScript for backend development, implemented a pre-write cleanup mechanism for the claude-prompts directory, ensuring that stale prompt files no longer persisted between job invocations. This solution provided idempotent and self-healing behavior, maintaining safety for hosted runners while improving reliability for self-hosted environments. The change closed a longstanding bug, reduced debugging time, and ensured more predictable prompt generation across both create-prompt and agent invocation flows. All updates were clearly documented and contributed to more robust backend operations.