> ## Documentation Index
> Fetch the complete documentation index at: https://docs.frankenpress.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Runtime matrix

> Supported PHP × WordPress combinations and how to pick one

`runtime` ships a multi-arch image for each supported PHP minor.
`site-template` runs a nightly compat-matrix that confirms each
PHP × WP combination still composes cleanly. This page is the source
of truth for which combinations are blessed.

## Supported combinations

|                   | PHP 8.3   | PHP 8.4   | PHP 8.5   |
| ----------------- | --------- | --------- | --------- |
| **WordPress 6.9** | supported | supported | supported |
| **WordPress 6.8** | supported | supported | supported |

PHP \< 8.3 is EOL or near-EOL upstream — out of scope. WordPress \< 6.8
is below the floor we commit to support.

The compat-matrix workflow runs on every PR to `site-template` plus
nightly at 06:00 UTC, so any regression introduced by an upstream WP
point release within `~6.8.0` / `~6.9.0` is caught within 24 hours.

## Tag schema

`runtime` publishes a multi-arch manifest list (`linux/amd64` +
`linux/arm64`) under each of these tags:

| Tag                     | Cadence                               | Example                         |
| ----------------------- | ------------------------------------- | ------------------------------- |
| `:php<X.Y>`             | rolling, on push to `main`            | `:php8.3`, `:php8.4`, `:php8.5` |
| `:php<X.Y>-<short-sha>` | every non-PR push                     | `:php8.4-abc1234`               |
| `:php<X.Y>-v<W.Z>`      | on `v*.*.*` tag push                  | `:php8.4-v0.2.0`                |
| `:v<W.Z>`               | on `v*.*.*` tag, **default PHP only** | `:v0.2.0`                       |

The unprefixed `:v<W.Z>` channel exists so consumers who don't care
which PHP they're on can pin a release without encoding the default.
The default PHP is **`8.3`** — see [Default-PHP cadence](#default-php-cadence).

## Picking a PHP

`site-template`'s `Dockerfile` defaults the runtime base to the
default PHP:

```dockerfile theme={null}
ARG FP_RUNTIME_IMAGE=ghcr.io/frankenpress/runtime
ARG FP_RUNTIME_VERSION=php8.3
```

To opt into a different PHP, either pin it in your fork's `Dockerfile`:

```dockerfile theme={null}
ARG FP_RUNTIME_VERSION=php8.4
```

…or override per-build:

```bash theme={null}
docker build --build-arg FP_RUNTIME_VERSION=php8.4 -t my-site:test .
```

Your site's CI (`build.yml`) honours the Dockerfile default; per-build
overrides only affect the invocation that sets them.

<Tip>
  To exercise your actual site code under a non-default PHP before
  flipping it, run `FP_RUNTIME_VERSION=php8.4 make build` locally.
  The compose harness picks up the override.
</Tip>

## Picking a WordPress minor

WordPress core is composer-installed at site-build time, gated by the
`roots/wordpress` constraint in your fork's `composer.json`:

```json theme={null}
{
  "require": {
    "roots/wordpress": "^6.8"
  }
}
```

`^6.8` admits both 6.8.x and 6.9.x; `composer install` resolves to the
highest matching point release at build time. To lock onto a specific
minor:

```bash theme={null}
composer require "roots/wordpress:~6.9.0"
```

`~6.9.0` admits patch releases (6.9.1, 6.9.2, …) but not 6.10. Useful
when an upstream minor introduces a regression for your stack and you
want a stable hold-line until it's fixed.

## Default-PHP cadence

The unprefixed `:v<W.Z>` channel always points at the **default PHP**,
currently `8.3`. The default is bumped deliberately — typically \~6
months after a new PHP minor reaches upstream-stable status, long
enough for early ecosystem incompatibilities to surface and be patched.

A default-PHP bump is a coordinated PR across `runtime` (the
`DEFAULT_PHP` env in `build.yml`) and this page. `site-template`
forks do **not** auto-bump; each site pins its own PHP via the
`FP_RUNTIME_VERSION` build arg.

## What's next

<CardGroup cols={2}>
  <Card title="runtime" icon="cube" href="/components/runtime">
    Build args, env vars, and the cache-invalidation contract.
  </Card>

  <Card title="Upgrade flow" icon="arrows-rotate" href="/operations/upgrade">
    `git tag` → CI → `helm upgrade` per environment.
  </Card>
</CardGroup>