Claude Code 2.1.277 reads AGENTS.md when no CLAUDE.md is present

Sources: changelog, HN discussion, second thread
Summary: The changelog entry for 2.1.277, dated 2026-09-18, adds a fallback to AGENTS.md for projects with no CLAUDE.md. The setting is under Project instructions in the /config menu. The fallback is not yet available on Bedrock, Vertex or Foundry.
Comments: HN commenters report the fallback runs in one direction only, and that skills under .agents/skills are still not discovered.
Why it matters: Teams maintaining parallel instruction files for several agents can collapse them into one, except on the three hosted backends that lack the fallback.