Standardize repository instructions for coding agents #7

Scope

Audit the root and nested agent-instruction files in data, engineer, backtest, specs, live, diagnostic, and models. Replace the historical directory-map sidecar design with a maintained cross-agent standard based on current Codex, Claude Code, GitHub Copilot, and AGENTS.md discovery behavior.

Confirmed starting state

• No managed release repository contains agents.txt; the existing convention is AGENTS.md.
• The seven repositories range from no tracked instructions to 24 AGENTS.md files.
• Data and Engineer have ignored local-only CLAUDE.md files; Diagnostic and Models have none on main.
• Many nested files are API and file inventories with stale line counts rather than local working constraints.
• Engineer exposes the sidecars through the installed package and a public get_agent_docs() API.

Acceptance criteria

• Publish an ecosystem standard defining filename, root and nested scope, size limits, required content, exclusions, Claude interoperability, distribution policy, and maintenance triggers.
• Record the dated audit evidence and authoritative research sources.
• Define automated conformance checks that validate discovery files without testing configuration tautologies.
• Create one implementation issue in each library only after the standard is reviewed.
• Do not merge library instruction changes until the ecosystem standard is accepted.