Support global AGENTS.md or custom default instructions for all sessions

[RajnarayanChoudhary]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

Currently AGENTS.md is project-specific (created by /init per project). There's no way to set default instructions that apply to all sessions/projects globally.

Proposed solutions (any of these):

(1) Global AGENTS.md - Load instructions from ~/.config/opencode/AGENTS.md for all sessions
(2) Agent default system prompt - Allow setting default system prompt in global config
(3) Startup hook/initialization - Run initialization script on every new session
This would let users set preferences once (like "show code in conversation") that apply everywhere without repeating at each session.

[github-actions]

This issue doesn't fully meet our contributing guidelines.

What needs to be fixed:

• Feature request titles must start with [FEATURE]: (e.g., [FEATURE]: Support global AGENTS.md or custom default instructions for all sessions)

Please edit this issue to address the above within 2 hours, or it will be automatically closed.

---

This issue might be a duplicate of existing issues. Please check:

• [FEATURE]: Allow custom system prompts in global, project or custom directories #7101: [FEATURE]: Allow custom system prompts in global, project or custom directories — this issue specifically proposes global system prompts at ~/.config/opencode/prompt/, which overlaps significantly with your proposal for a global ~/.config/opencode/AGENTS.md

If you believe this was flagged incorrectly, please let a maintainer know.

[github-actions]

This issue has been automatically closed because it was not updated to meet our contributing guidelines within the 2-hour window.

Feel free to open a new issue that follows our issue templates.