Changelog

All notable changes to the AHP specification are documented here.

Format: [version] YYYY-MM-DD — description

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[0.1] 2026-02-21 — Initial draft

• Initial specification covering MODE1, MODE2, and MODE3
• Discovery mechanisms: well-known URI, Accept header, HTML link tag, in-page agent notice
• AHP Manifest schema
• Conversational endpoint request/response format
• Multi-turn session protocol with session_id
• Content signals: ai_train, ai_input, search, attribution_required
• Trust & identity model (v0: unverified, declaration-based)
• Async model for MODE3 long-running capabilities
• Rate limiting: headers, recommended limits, cost-based throttling
• Error handling with standard codes
• Versioning and backwards compatibility policy
• Security considerations: prompt injection, SSRF, data exfiltration
• Appendix B: relationship to and migration path from llms.txt