authoring-github-workflows

This error means GitHub Actions rejected the workflow file at load time, so no jobs started. A common cause is a `#` inside an unquoted `${{ }}` expression being parsed as a YAML comment, truncating the value into an unterminated expression. Quote the scalar and validate with actionlint.

Run actionlint against your workflow files, for example `actionlint -shellcheck= -pyflakes= .github/workflows/*.yml`. It understands the Actions schema and expression grammar, catching errors that plain YAML linters miss. A clean exit code 0 means the workflows are structurally valid.

Quote the entire scalar when the value contains a `#` preceded by a space, a colon followed by a space, or a leading special character like `*`, `&`, `!`, `@`, or backtick. Prefer double quotes when the inner expression uses single quotes, and never escape the `${{ }}` braces.

No. YAML-only parsers accept the truncated-comment form where a `#` silently cuts off an expression, so they report success on workflows GitHub Actions will refuse to run. Only actionlint (or pushing and watching Actions parse it) validates the Actions layer.

No. It covers only syntactic and structural correctness of workflow YAML — quoting, parsing, and actionlint-level validity. For semantic and functional workflow design, including agentic-workflow behavior, use the complementary agentic-workflows agent guidance instead.