Bug report info

act version:            0.2.88
GOOS:                   darwin
GOARCH:                 arm64
NumCPU:                 12
Docker host:            unix:///Users/.../docker.sock
Sockets found:
Config files:
        /Users/.../Library/Application Support/act/actrc
        /Users/.../.actrc
Build info:
        Go version:            go1.24+
        Main path:             github.com/nektos/act
        Main version:          0.2.88

Command used with act

act -l

Describe issue

act rejects valid workflows that use concurrency.queue, which GitHub officially documents under the workflow-syntax reference. Any workflow with queue: single or queue: max under concurrency fails schema validation at parse time, so the listing/run never starts.

Relevant references:

• GitHub docs entry: https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#concurrency
• Docs commit that added queue: github/docs@336b7f5
• SchemaStore already encodes the enum (single | max, default single) in github-workflow.json under #/definitions/concurrency: https://raw.githubusercontent.com/SchemaStore/schemastore/master/src/schemas/json/github-workflow.json
• Cross-reference in actionlint: Actionlint does not know about queue: key for concurrency rhysd/actionlint#657

Per the docs, queue accepts single (default — at most one pending run) or max (up to 100 pending runs). The docs also state that queue: max combined with cancel-in-progress: true is a workflow validation error, but that mutual-exclusion is documented in prose only and not encoded in SchemaStore.

Link to GitHub repository

No response

Workflow content

name: queue-test
on: pull_request
concurrency:
  group: g
  queue: max
jobs:
  noop:
    runs-on: ubuntu-latest
    steps:
      - run: echo ok

Relevant log output

Error: workflow is not valid. 'queue.yml': Line: 4 Column 3: Failed to match string: Line: 4 Column 3: Expected a scalar got mapping
Line: 4 Column 3: Failed to match concurrency-mapping: Line: 6 Column 3: Unknown Property queue
Actions YAML Schema Validation Error detected:
For more information, see: https://nektosact.com/usage/schema.html

Additional information

Tracked in pkg/schema/workflow_schema.json - the concurrency-mapping definition lists only group and cancel-in-progress.