startup-context

name	startup-context
description	Validate and diagnose startup context files — CLAUDE.md, AGENTS.md, rules, and .cursorrules — that inject instructions into the model context at session start across Claude Code, Cursor, and Codex. Use when this capability is needed.
metadata	{"author":"eyelock"}

Use this skill when working with files that inject instructions at startup — validating format, diagnosing why instructions aren't being read, or understanding load order and precedence per vendor.

What startup context is: Files that are automatically loaded into the model's context before any user prompt. Each vendor uses different file names and locations. All serve the same purpose: priming the model with project-specific or harness-level instructions.

Vendor mapping:

Vendor	Primary file	Rules format	Legacy
Claude Code	CLAUDE.md	.claude/rules/*.md	—
Cursor	.cursor/rules/*.mdc	.cursor/rules/*.mdc	.cursorrules (root)
Codex	AGENTS.md	NOT SUPPORTED in plugins	—

Load order (Claude Code): User CLAUDE.md (~/.claude/CLAUDE.md) → Project CLAUDE.md → Plugin CLAUDE.md (via @-import). Rules in .claude/rules/ are loaded after CLAUDE.md.

The @AGENTS.md workaround (Claude Code): Claude Code does not natively read AGENTS.md. When ynh exports for Claude, it writes a CLAUDE.md containing only @AGENTS.md — using Claude's @-import syntax to pull in the cross-vendor instructions file without duplicating content.

Diagnostic checklist:

1. Is the file in the right location for the vendor?
2. Claude Code: does the plugin CLAUDE.md use @-import correctly?
3. Cursor: is the rules file .mdc (not .md)? Does it have required frontmatter (description, globs, alwaysApply)?
4. Codex: rules are not supported in plugin format — use AGENTS.md only
5. Check file encoding and line endings — bare CR can cause silent failures

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Source: eyelock/assistants — distributed by TomeVault.