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Anthropic models ignore Custom Instructions #8892
Description
Description
The Custom Instructions feature documented at https://opencode.ai/docs/rules/#custom-instructions does not work with Anthropic models.
From docs:
"You can specify custom instruction files in your opencode.json [...] This allows you and your team to reuse existing rules rather than having to duplicate them to AGENTS.md."
"All instruction files are combined with your AGENTS.md files."
Expected behavior
Files specified in instructions array are automatically combined with AGENTS.md and included in the LLM context. The model should follow these rules.
Actual behavior
Anthropic models (Claude Sonnet 4.5, Opus 4.5, Haiku 4.5) completely ignore content from instructions array. The same configuration works correctly with OpenAI and Groq models.
Reproduction
// opencode.json
{
"$schema": "https://opencode.ai/config.json",
"instructions": ["my-rules.md"]
}- Add any rule to my-rules.md
- Start opencode, select Anthropic model
- Ask a question where the rule should apply
- Rule is ignored
Switch to OpenAI/Groq → rule is applied.
Environment
- opencode v1.1.21
- macOS
- Tested with multiple Anthropic models
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github-actions commentedon Jan 16, 2026
This issue might be a duplicate of or related to existing issues. Please check:
Feel free to ignore if these don't address your specific case.
pedropombeiro commentedon Feb 3, 2026
Still seeing this in v1.1.49, FWIW.
rekram1-node commentedon Feb 3, 2026
What provider? Anthropic?
pedropombeiro commentedon Feb 3, 2026
Yes, Anthropic and also GitLab with Anthropic-based models.
github-actions commentedon Apr 5, 2026
To stay organized issues are automatically closed after 90 days of no activity. If the issue is still relevant please open a new one.