Make AGENTS.md the source of truth with CLAUDE.md as a symlink

[billadunblock]

Summary

• Make AGENTS.md the single source of truth for AI coding agent instructions, replacing CLAUDE.md with a symlink to it — AGENTS.md is the tool-agnostic industry convention (used by Codex, Cursor, and others; see agents.md), while the symlink keeps Claude Code working by its conventional filename with zero duplication or drift.
• Drop the old AGENTS.md redirect stub and its fallback summary, so there is only one copy of the rules.
• Update all in-repo references (PR template, onboarding docs, agent and command definitions) to point at AGENTS.md.

Changes

File	Change
AGENTS.md	Now holds the full agent guide (moved from CLAUDE.md via git mv, so git log --follow preserves history); redirect stub removed
CLAUDE.md	Replaced with a symlink to AGENTS.md (mode 120000)
.github/pull_request_template.md	Checklist link now points at AGENTS.md
docs/guide/onboarding.md	Docs table entry now references AGENTS.md
.claude/agents/code-simplifier.md	Reference updated to AGENTS.md
.claude/agents/pr-reviewer.md	Reference updated to AGENTS.md
.claude/commands/review-changes.md	Reference updated to AGENTS.md

Closes

N/A — issues are disabled on this repository.

Test plan

• Docs format: cd docs && npm run format
• Other: head CLAUDE.md resolves through the symlink to the AGENTS.md content; git log --follow AGENTS.md shows the preserved history

No Rust or JS code is touched, so the cargo and vitest gates don't apply to this change.

Checklist

• Changes follow AGENTS.md conventions
• No unwrap() in production code — use expect("should ...") (no Rust changes)
• Uses tracing macros (not println!) (no Rust changes)
• New code has tests (no code changes)
• No secrets or credentials committed

Notes

• Windows: Git for Windows defaults to core.symlinks=false unless symlink support is available (Windows Developer Mode enabled, or an elevated shell). With symlinks disabled, git checks out CLAUDE.md as a plain one-line text file containing the path AGENTS.md instead of a real symlink, so tools that read CLAUDE.md would see the pointer text rather than the instructions. To get a real symlink: enable Developer Mode (Settings → System → For developers), then clone with git clone -c core.symlinks=true, or in an existing clone run git config core.symlinks true followed by git checkout -f CLAUDE.md to re-materialize it.

References

• agents.md — the open AGENTS.md specification: a simple, tool-agnostic Markdown convention for giving coding agents project instructions.
• openai/agents.md — the spec's source repository, with examples and the list of supporting tools.
• Claude Code memory docs — Claude Code loads CLAUDE.md from the project root, which the symlink satisfies while keeping AGENTS.md as the single source.

[billadunblock]

@jevansnyc as we expand agent harnesses and enrich agentic workflows, this change can be pretty handy (prioritize AGENT.md wth CLAUDE.md as symlink). Consider for corporate users, they can only use Claude Code Enterprise plan (data not for training) which is not very practical for the token price, multi harnesses would be ideal in lots of cases.