add act

Author: nullstyle

.actrc

@@ -0,0 +1,5 @@
+-W .github/workflows/ci.yml
+-P ubuntu-latest=catthehacker/ubuntu:act-latest
+-P macos-latest=catthehacker/ubuntu:act-latest
+-P windows-latest=catthehacker/ubuntu:act-latest
+--container-architecture linux/amd64

.mise.toml

@@ -1,4 +1,5 @@
 [tools]
+act = "latest"
 deno = "latest"
 go = "latest"
 just = "latest"

Justfile

@@ -56,6 +56,18 @@ ci:
     zig build test --summary all
     just e2e
 
+# List CI workflow jobs as seen by `act`
+act-list:
+    act -W .github/workflows/ci.yml -l
+
+# Run GitHub Actions CI workflow locally with `act`
+act-ci event="pull_request":
+    act {{ event }} -W .github/workflows/ci.yml
+
+# Run a single CI job locally with `act` (example: `just act-ci-job test`)
+act-ci-job job event="pull_request":
+    act {{ event }} -W .github/workflows/ci.yml -j {{ job }}
+
 # Install to a local bin path (defaults to ~/.local/bin)
 install dest="${HOME}/.local/bin": release
     mkdir -p "{{ dest }}"

README.md

@@ -23,6 +23,7 @@ A pure Zig implementation of [Cap'n Proto](https://capnproto.org/) -- a serializ
 - Cap'n Proto compiler (`capnp`) - optional, for schema compilation
 - `mise` (recommended, for environment management)
 - `just` (recommended, for task automation)
+- Docker (optional, for local GitHub Actions runs via `act`)
 
 ### Building from Source
 
@@ -329,6 +330,28 @@ zig build test-codegen       # Codegen tests
 just e2e                    # Cross-language interop harness
 ```
 
+### Run GitHub Actions Locally
+
+Use [`act`](https://github.com/nektos/act) to run `.github/workflows/ci.yml` on your machine.
+
+```bash
+# Install toolchain declared in mise config (includes act)
+mise install
+
+# List available CI jobs
+just act-list
+
+# Run CI workflow locally (default event: pull_request)
+just act-ci
+
+# Run a single job
+just act-ci-job test
+```
+
+Notes:
+- The repo `.actrc` maps all matrix runner labels to a Linux container image for local execution.
+- Ensure Docker is running before invoking `act`.
+
 ### Test Coverage
 
 - Message wire-format encode/decode, pointer resolution, limits, and malformed/fuzz inputs