{"name":"RUNNER_OS","slug":"runner-os","family":"env","title":"Environment variables","noun":"environment variable","description":"When `GITHUB_ACTIONS` is truthy, the value of `RUNNER_OS` is recorded as `githubActionsRunnerOs` in the `envContext` metadata built for Claude Code's events. It is also read into the `runnerOs` field of a separate environment-facts object.","description_source":"code","described_by":{"bundle":"2.1.286","author":"claude-opus-5-5"},"presence":{"first_seen":"2.1.138","removed_in":null,"in_current_build":true,"newest_mined":"2.1.308","builds":149,"mined_builds":149,"first_cited":null},"aliases":[],"entries":[],"entries_total":0,"docs":[],"docs_total":0,"gates":[],"related":[{"name":"RUNNER_ENVIRONMENT","slug":"runner-environment","description":"CLAUDE_CODE_SUBAGENT_MODEL_FORCE joins a list of passed-on env vars, and RUNNER_ENVIRONMENT is added next to GITHUB_ACTIONS"}],"url":"https:\/\/changelogs.core-directive.com\/reference\/env\/runner-os","family_url":"https:\/\/changelogs.core-directive.com\/reference\/env.json"}