fledge-hello-rust

Example fledge plugin written in Rust, demonstrating the fledge-v1 protocol. Exercises every message type in a single interactive walkthrough.

Building

cargo build --release

Or with fledge:

fledge run build

Installing

fledge plugin install ./path/to/fledge-plugin-hello-rust
fledge hello-rust

Message types demonstrated

#	Type	Direction	What happens
1	log	plugin -> fledge	Colored structured logging
2	output	plugin -> fledge	Raw text passthrough
3	prompt	plugin -> fledge -> plugin	Ask for text input with validation
4	confirm	plugin -> fledge -> plugin	Yes/no dialog
5	select	plugin -> fledge -> plugin	Pick one from a list
6	multi_select	plugin -> fledge -> plugin	Pick multiple from a list
7	progress	plugin -> fledge	Determinate progress bar
8	store / load	plugin -> fledge	Key-value persistence roundtrip
9	exec	plugin -> fledge -> plugin	Sandboxed shell command
10	metadata	plugin -> fledge -> plugin	Project context query
11	progress (spinner)	plugin -> fledge	Indeterminate spinner

Protocol overview

The fledge-v1 protocol uses newline-delimited JSON (NDJSON) over stdio:

• stdin receives messages from fledge (init, response, cancel)
• stdout sends messages to fledge (prompt, log, output, etc.)
• stderr goes directly to the terminal (debug output)

The plugin lifecycle:

1. Fledge sends an init message with project context
2. Plugin sends outbound messages (requests or fire-and-forget)
3. For requests (prompt, confirm, select, load, exec, metadata), read the response from stdin
4. Exit with code 0 on success

Writing your own Rust plugin

Copy this project as a starting point. The key patterns:

• Define an OutboundMessage enum with #[serde(tag = "type")] for clean serialization
• Use a simple PluginIO struct to wrap stdin/stdout with JSON line reading/writing
• Handle cancel messages in the response reader so Ctrl+C works
• Use eprintln! for debug output (stderr is never captured)