Authoring GitHub Actions Workflows Safely GitHub Actions workflow files are YAML, but valid YAML is not the same as a valid workflow . A workflow can parse cleanly with yaml.safe_load (or a casual review) yet still be rejected by GitHub Actions at load time — producing the opaque failure "This run likely failed because of a workflow file issue" with zero jobs started . This skill teaches the YAML-vs-Actions traps (the

-as-comment trap above all), how to quote expression scalars correctly, and how to validate with actionlint before merge. Scope: syntactic vs. semantic. This skill is about the syntactic and structural correctness of workflow YAML — quoting, parsing, and actionlint -level validity that determines whether GitHub Actions will load and run a file at all. It is not about what a workflow should do or how an agentic workflow should behave. For semantic and functional guidance (designing workflow logic, agentic-workflow patterns, gh-aw authoring), use .github/agents/agentic-workflows.agent.md . The two are complementary: get the behavior right with the agent, get the YAML right with this skill. When to Use Editing, adding, or reviewing any file under .github/workflows/ . Writing a run-name , name , if , env , with , or run value that embeds a ${{ }} expression. A workflow run failed with "This run likely failed because of a workflow file issue" and no jobs ran . Eval/CI on main suddenly breaks for every run after a workflow edit merged, even though the change "looked fine." Deciding whether a YAML scalar needs quoting. When Not to Use Authoring non-Actions YAML (app config, Kubernetes, Compose, Azure Pipelines, GitLab CI). Pure shell/script logic inside an already-valid run: block (that is a scripting task, not a workflow-syntax task). Show more Installs 983 Repository dotnet/skills GitHub Stars 5.3K First Seen Jun 17, 2026 Security Audits Gen Agent Trust Hub Pass Socket Pass Snyk Pass