Coming from GitHub Actions

neosource CI aims to be familiar, not identical. Most of a GitHub Actions workflow carries over unchanged. Some of it carries over with behaviour you need to know about. Some of it does not work at all yet.

This page is the inventory. It is deliberately blunt: a compatibility page that oversells is worse than no page, because you find out at 2am.

Start here: two things to do first

Move the files. .github/workflows/ is not read, and no diagnostic is produced. Move your workflows to .neosource/workflows/ or nothing will ever run. Only the top level of that directory is read, and only on your default branch.
Replace images with packages. image: on a job is a hard parse error; container: is silently ignored. Jobs declare tools instead — see The job environment.

# before
container: node:20

# after
runs-on: nix
packages: [nodejs_20]

Works

These behave as you expect.

Feature	Notes
Workflow file syntax	Same YAML shape, `.yml` or `.yaml`.
`name`, `jobs`, `steps`	Unchanged.
`run:` steps	Unchanged.
`env:` at workflow, job and step level	Same precedence: step > job > workflow.
`needs:`	Enforced server-side; dependants are skipped transitively when a dependency fails.
Step-level `if:`	Evaluated.
`strategy.matrix`	Free-form axes, plus `include`, `exclude`, `fail-fast`, `max-parallel`.
Job `outputs:`	Unchanged.
`continue-on-error`, `timeout-minutes`	Both job and step level.
`working-directory:`	Unchanged.
`shell:`	`bash`, `sh`, `python`, `pwsh`/`powershell`.
`services:`	Real container images, with `env`, `ports` and `healthcheck`.
`${{ … }}` expressions	Contexts: `env`, `steps`, `needs`, `matrix`, `github`, `runner`, `inputs`, `secrets`, `vars`, `job`, `strategy`.
`${{ secrets.NAME }}`	Secrets are managed per workspace via the API.
`actions/checkout`	Native implementation. Version suffix ignored.
`actions/upload-artifact`, `actions/download-artifact`	Native implementations.
`actions/setup-*` toolchains	Native: node, python, go, bun, java, dotnet, ruby, deno, zig, php, haskell, plus `erlef/setup-beam`, `oven-sh/setup-bun`, `dtolnay/rust-toolchain`.
Third-party actions	Fetched from github.com as `owner/repo@ref`. Composite, Docker and Node (`node12`/`16`/`20`) actions run.

Works, with caveats

These work, but not exactly the way they do on GitHub.

Feature	Caveat
Workflow location	`.neosource/workflows/`, top level only, indexed from the default branch only. Subdirectories are ignored.
`on: pull_request`	Fires on opened and synchronize only. Other `types:` — `reopened`, `closed`, `labeled` — never fire, even if you list them.
Branch and path globs	Custom matcher, anchored at both ends: `` does not cross `/`, `` does. `release/` matches `release/v1` but not `release/v1/rc1`.**
`paths` / `paths-ignore`	Degrade to matching everything when the changed-path set is unknown or exceeds 1000 paths — the run happens rather than being skipped.
`runs-on:`	Scheduling label only. No value selects a different image or OS.
Unmodeled GitHub keys	`permissions:`, `defaults:`, `run-name:`, `environment:`, `secrets: inherit` are accepted, warned about, and ignored. Your workflow still runs.
`container:`	Warned and ignored — the job runs in the canonical environment regardless.
`with:` inputs	Must be scalars. A list or map value is a parse error.
Third-party actions	Fetching requires network egress to github.com at job time.
Parse diagnostics	Persisted and returned by the workflows API, but the web UI does not render them. A warning is effectively invisible unless you query the API.
Platform	Linux only.

The diagnostics caveat compounds the others: an ignored container:, a dropped trigger, or a misspelled key produces a warning nobody sees. After migrating, it is worth reading GET /api/repos/{owner}/{repo}/workflows once and checking the warnings array on each workflow.

Not yet

These do not work. Plan around them.

Feature	Status
`.github/workflows/`	Not read at all, and no warning is produced. Silent no-CI.
`image:` on a job	Hard parse error, with a pointer to `packages:`.
`concurrency:`	Ignored. Two quick pushes start two runs and neither cancels the other. There is no cancel-in-progress.
Job-level `if:`	Parsed but never evaluated — a condition on a job does not gate it. Use step-level `if:`.
`tags:` / `tags-ignore:`	Parsed and discarded. A workflow filtering only on tags fires on every push.
`on: workflow_dispatch`	Parses, but no endpoint dispatches it. Use `POST /api/workflow-runs` for manual runs.
`on: repository_dispatch`	Parses, but nothing dispatches or receives it.
`on: change`	Not implemented. A hard parse error when it is a workflow’s only trigger; a warning otherwise.
Reusable workflows (`jobs.<id>.uses:`)	Not supported. That job is skipped with a warning; its siblings still run.
`permissions:`	Ignored — no per-job token scoping.
Deployment `environment:`	Ignored — no environments, approvals or protection rules.
Self-hosted runners	The API exists, but the agent is not distributed. See Runners.
Windows and macOS runners	Linux only.
Other trigger events	`release`, `issues`, `workflow_run` and the rest warn and drop that trigger.

A migrated workflow

Putting it together:

name: CI
on:
  push:
    branches: [main]
  pull_request:

env:
  CARGO_TERM_COLOR: always

jobs:
  test:
    runs-on: nix
    packages: [rustc, cargo]
    strategy:
      matrix:
        rust: [stable]
    steps:
      - uses: actions/checkout@v4
      - run: cargo test

  lint:
    runs-on: nix
    packages: [rustc, cargo, clippy]
    needs: [test]
    steps:
      - uses: actions/checkout@v4
      - run: cargo clippy -- -D warnings

Note what is absent: no container:, no permissions:, no concurrency:. Those would parse, but three of them would be silently ignored.