Goose adds unstable ACP method to override or append session system prompts

{
  "event_id": "event_67f5257d22113948",
  "topic_id": "ai_coding",
  "event_type": "Pull Request",
  "event_time": "2026-05-29T00:49:14Z",
  "title": "Goose adds unstable ACP method to override or append session system prompts",
  "summary": "Goose introduces an unstable ACP API that allows external controllers to replace the base system prompt or append keyed instructions per session, along with helpers to clear overrides.",
  "contribution": "Provides a programmatic ACP endpoint to dynamically set, append, or clear system prompts at the session level, enabling external tools to steer the agent's base instructions without modifying core configuration files.",
  "impact": "Developers integrating Goose into custom workflows can now dynamically steer the agent's core instructions per session, reducing the need to restart or reconfigure the agent when switching tasks. The implementation exposes an unstable ACP method for replacing or appending keyed prompts, with new SDK schema updates and clearing helpers. Teams should monitor how prompt overrides interact with Goose's internal context window and whether unstable ACP methods stabilize or change signatures in upcoming releases.",
  "maturity": "Code",
  "confidence": 0,
  "importance_score": 0.78,
  "risk_flags": [
    "Unstable Api",
    "Prompt Override Conflicts",
    "Context Window Pressure"
  ],
  "evidence_count": 1
}