Root AGENTS.md not auto-loaded at session start when no CLAUDE.md exists

Bug description

A root AGENTS.md is not loaded into context at session start, even though the repository contains no CLAUDE.md anywhere and no claudeMd/claudeMdExcludes settings. Per the documented fallback behavior, AGENTS.md should be read in place of CLAUDE.md when the latter is absent.

The model confirmed no project-instruction content was injected at startup — the AGENTS.md contents only entered context after being explicitly @-mentioned by the user.

Environment

• Claude Code version: 2.1.246
• OS: Windows 11 Enterprise (10.0.26200)
• Shell: PowerShell
• Model: Fable 5

Steps to reproduce

1. Create a repository with a root AGENTS.md (project instructions) and no CLAUDE.md in the repo or any parent directory.
2. No project .claude/settings.json / settings.local.json (nothing excluding memory files).
3. Start a Claude Code session in that directory (Windows, PowerShell).
4. Ask Claude what project instructions it has in context.

Expected behavior

Root AGENTS.md is loaded at session start, exactly as a root CLAUDE.md would be (documented CLAUDE.md-fallback behavior).

Actual behavior

No memory/system-reminder injection of AGENTS.md content occurs. /context shows no project instructions loaded. The file is only read when explicitly @-mentioned.

Additional notes

• The repository also has nested AGENTS.md files (cli/AGENTS.md, cmd/AGENTS.md); the issue observed is about the root file at session start.
• Workaround: adding a root CLAUDE.md containing @AGENTS.md works as expected.