Claude Code Bows to 5,200 Likes, Adopts AGENTS.md

Claude Code version 2.1.277 now reads AGENTS.md when CLAUDE.md is absent, ending a 13-month standoff over AI project instruction files.

Starting with version 2.1.277 released September 19, Claude Code will automatically locate and read AGENTS.md if no CLAUDE.md exists in a project folder — the first line of the release notes states the change. According to 36Kr, the announcement came from Claude Code core engineer Thariq on X, where the thread passed one million views within an hour. AGENTS.md is the open instruction-manual format launched by OpenAI in August 2025 and supported by Codex, Cursor, GitHub Copilot, Gemini CLI and Devin; 36Kr reports more than 60,000 open-source projects now use it, and OpenAI donated the format to the Linux Foundation's Agentic AI Foundation, where Anthropic sits as a platinum member.

The reversal is notable because 36Kr reports the 'Please support AGENTS.md' GitHub issue has been open since August 2025, accumulating over 5,200 likes and 300+ comments — the highest-voted feature request in the entire Claude Code repository, four times the second-ranked request. Until now, mixed-tool teams had to maintain two nearly identical instruction manuals, or resort to soft-linking the files, importing via @AGENTS.md references, or startup hooks that injected AGENTS.md content into every conversation. 36Kr notes the awkwardness of Anthropic and OpenAI sitting in the same open-standards foundation while their flagship coding tools refused to read each other's manuals. The Codex team's head Tibo immediately celebrated: 'Yay! This is the way. Come to the light.'

According to 36Kr, Thariq posted a second thread with bigger news: AGENTS.md support was implemented as a Claude Code 'mod,' and mods are Anthropic's upcoming customization mechanism for modifying the harness — the underlying runtime framework of Claude Code itself. AGENTS.md is the first built-in mod, with source code placed in the mods/agents-md directory of the official repository, letting developers eventually build custom versions of how project instructions are read. 36Kr draws a contrast with DeepSeek Harness, the 'everything is a plugin' open-source framework open-sourced a month earlier that has drawn 229,000 GitHub stars: DeepSeek builds from scratch on the Cordis kernel, while mods open ports on a mature finished product. Either way, 36Kr observes, the runtime framework of coding agents is no longer a black box.

The compatibility news lands amid a legal backdrop that worries open-source developers. devops.com reports the Ninth Circuit ruled on September 16 in Doe v. GitHub that AI-generated code lacking copyright management information does not automatically violate Section 1202 of the DMCA, handing GitHub, Microsoft and OpenAI a significant win. Writing for the court, Judge Eric Miller held that one who creates a new work without including CMI 'cannot be said to have removed or altered anything.' devops.com notes the ruling does not resolve whether training on open-source code infringes copyright; Software Freedom Conservancy's Karen Sadler told devops.com it is 'very easy to overread this decision,' and OSI's Duane O'Brien stressed license obligations remain before the district court.

For working developers, the immediate effect is simple: repositories already configured with AGENTS.md for other agents can now be used with Claude Code as-is — no added CLAUDE.md, no import rules, no settings changes — and the makeshift workarounds of the past year can be discarded, as 36Kr reports. The longer arc is customization: 36Kr says developers were already disassembling the mods source on launch day to study the hook mechanism and lifecycle, with some arguing mods are the real protagonist of the update and AGENTS.md merely its first demonstration. As mods mature, expect community-built variations in how coding agents read project instructions, alongside continued litigation over AI use of open-source code that devops.com says still has 'a lot of litigation and court decisions to come.'