zRPC Plugin Reference

Environment Variables

Variable	Required	Description
`EDGEPLANE_ZRPC_PLUGIN_PATH`	Yes (to enable)	Absolute path to `edgeplane_zrpc.wasm`. If unset, `edgeplaned` uses the paste path — no behavior change.
`EDGEPLANE_ZRPC_SESSIONS`	Yes (to enable)	Comma-separated list of Zellij session names to watch.

Both must be set for the plugin to activate.

Permissions

The plugin requires these Zellij permissions, pre-seeded in permissions.kdl before the Zellij server starts:

Permission	Why
`ReadApplicationState`	Read pane list and pane state
`ReadCliPipes`	Receive commands sent via `zellij pipe`
`WriteToStdin`	Inject text into pane PTY stdin
`ReadPaneContents`	Read scrollback buffer
`ChangeApplicationState`	Send focus events (optional)

Find your Zellij cache directory:

zellij setup --check | grep 'CACHE DIR'

The permissions.kdl file format (raw absolute path as the node name — no file: prefix):

"/absolute/path/to/edgeplane_zrpc.wasm" {
    ReadApplicationState
    ReadCliPipes
    WriteToStdin
    ReadPaneContents
}

Pipe Protocol

The plugin communicates over the edgeplane-zrpc named Zellij pipe. All payloads are JSON.

Commands (edgeplaned → plugin)

`kind`	Fields	Description
`ping`	—	Health check
`inject`	`pane_id: number, text: string`	Inject text + newline into pane PTY stdin
`scrollback`	`pane_id: number, lines: number`	Request scrollback contents
`list_panes`	—	Request current pane manifest

Responses (plugin → edgeplaned)

`kind`	Fields	Description
`pong`	—	Response to `ping`
`scrollback_response`	`pane_id: number, content: string`	Scrollback content
`pane_list`	`panes: [{id, title, is_focused}]`	Pane manifest
`pane_event`	`event: "exit"\|"focus_gained"\|"resize", pane_id: number`	Lifecycle event

Example: inject a prompt

# Sent by edgeplaned internally — shown here for debugging
zellij pipe --name edgeplane-zrpc -- '{"kind":"inject","pane_id":1,"text":"run tests"}'

Build Details

The plugin is a Rust bin crate targeting wasm32-wasip1. This is required — a cdylib on wasm32-wasip1 with Rust 1.82+ exports _initialize (WASI reactor) instead of _start (WASI command). Zellij 0.44.x requires _start and silently fails to instantiate reactor plugins; all subsequent zellij pipe calls hang indefinitely.

Build:

cargo build --release --target wasm32-wasip1 -p edgeplane-zrpc

Verify _start is exported:

wasm-tools print target/wasm32-wasip1/release/edgeplane_zrpc.wasm | grep '(export "_start"'

Logs

Filter edgeplaned logs for zRPC activity:

journalctl --user -u edgeplaned -f | grep zrpc

Zellij log for plugin instantiation failures:

tail -f "$(zellij setup --check | grep 'LOG DIR' | awk '{print $3}')/zellij.log" | grep edgeplane

What’s Next

Guides: Zellij Integration — end-to-end setup walkthrough
Architecture: Components — where the plugin fits