* 🐛 Fix plugin postMessage channel allowing cross-plugin message injection
The global postMessage listener was broadcasting incoming messages to all
loaded plugins without validating the origin or routing to the correct
sender. This allowed any plugin (or any iframe from any origin) to inject
messages into other plugins.
- Added origin validation — messages from origins other than
window.location.origin are rejected.
- Added sender-based routing — a message is only delivered to the plugin
whose iframe contentWindow matches event.source.
- Exposed iframeWindow getters in PluginManager, PluginModalElement, and
createPlugin so the runtime can compare event.source against the correct
iframe reference.
- Updated documentation examples to include origin validation and
recommend window.location.origin over '*' for postMessage targetOrigin.
AI-assisted-by: qwen3.7-plus
* 🐛 Fix plugin origin check breaking cross-origin plugin messaging
The origin check added in the previous commit compared event.origin
against window.location.origin (Penpot own origin). Since plugins
are cross-origin by design (hosted on the plugin author domain),
this check rejected every legitimate message from every real plugin.
The event.source-based sender routing (matching iframeWindow identity)
is the correct and sufficient security mechanism - it cannot be forged
cross-origin, so the redundant origin check was removed.
- Removed event.origin check from load-plugin.ts message listener
- Updated tests to use realistic plugin origins (localhost:4202/4203)
and to verify rejection based on source identity, not origin
- Fixed documentation examples: use event.source for receiving
validation and '*' for postMessage targetOrigin
AI-assisted-by: mimo-v2.5-pro
Andrey Antukh