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Claude Code 2.1.277 Reads AGENTS.md Only When CLAUDE.md Is Absent

Author Editor

The 18 September 2026 release falls back to AGENTS.md. CLAUDE.md still wins unless the project setting loads both.

Harness Engineering Claude Code AGENTS.md

Direct answer

Claude Code 2.1.277 reads AGENTS.md only when no CLAUDE.md exists in the working directory or any parent. The default project setting is claude-md-or-agents-md, and v2.1.281 later extended that fallback to Bedrock, Vertex, and Foundry.

Claude Code 2.1.277, shipped on 18 September 2026, can read AGENTS.md. The default is a fallback, not a merge. If the working directory or any parent already has a CLAUDE.md, Claude Code uses that file and ignores AGENTS.md. Only a tree with no CLAUDE.md picks up the shared instructions file.

DevOps.com quotes the Claude Code team: if there is no CLAUDE.md in a folder, Claude checks for AGENTS.md. The Project instructions control in /config has four values. The default, claude-md-or-agents-md, is the fallback just described. claude-md-and-agents-md loads both, with CLAUDE.md first. claude-md ignores AGENTS.md. managed-only loads the organization's managed file and auto memory.

The first release did not cover every host

The 2.1.277 notes say the feature is not on Bedrock, Vertex, or Foundry. Sessions that do not fetch Anthropic feature flags, including telemetry-off sessions, also miss it, and so does the first session after an install. In those cases the documented path is to import AGENTS.md from a CLAUDE.md. v2.1.281, on 23 September 2026, changes that limit and turns the same fallback on for Bedrock, Vertex, Foundry, gateways, and telemetry-disabled sessions.

A repo shared by several coding agents can keep one AGENTS.md. Claude Code will honor it on 2.1.277 only when it does not also see a CLAUDE.md. Teams that need both files have to flip the project setting or add the import.

Source: DevOps.com.

FAQ

How do you load both files?
Set Project instructions in /config to claude-md-and-agents-md, which loads CLAUDE.md first, or start CLAUDE.md with an @AGENTS.md import.
Does the fallback work on Bedrock?
Not in 2.1.277. v2.1.281, dated 23 September 2026, extends AGENTS.md support to Bedrock, Vertex, Foundry, gateways, and sessions with telemetry disabled.