refactor(hu): abort leaked plugin tasks, harden config, drop legacy world

Address PR #236 review findings in crates/hiroz-union:

- Abort background tokio tasks on drop: add Drop impls that call
  AbortHandle::abort() for subscription/raw-sub/liveliness/queryable/
  rate-tracker state, and break the rate-tracker loop when the receiver
  is gone. Prevents unbounded task accumulation across plugin reload.
- Share a single process-wide WASM engine (OnceLock) with one epoch
  ticker for its lifetime, instead of spawning a fresh engine+ticker on
  every load_plugins/load_plugin_named call.
- Escape untrusted manifest endpoints through serde_json when building
  the connect/endpoints config array (was raw format! interpolation).
- Deduplicate load_plugins/load_plugin_named into a shared load_from.
- Replace the DispatchOutcome enum with Option<u32> and update callers.
- Remove the never-shipped v0.3 legacy hu-plugin alias world:
  PluginBindings::Legacy, try_load_legacy, plugin-event variant, and the
  tui_bindgen module (the top-level bindgen now targets hu-tui-plugin).
- Drop the deprecated --headless/--web CLI flags.

Author: YuanYuYuan

crates/hiroz-union/src/main.rs

@@ -54,10 +54,6 @@ struct Cli {
     #[arg(long, value_enum, default_value = "rmw-zenoh", global = true)]
     backend: Backend,
 
-    /// Deprecated: use `hu stream`. JSON streaming to stdout.
-    #[arg(long, global = true, hide = true)]
-    headless: bool,
-
     /// Output structured JSON logs
     #[arg(long, global = true)]
     json: bool,
@@ -74,10 +70,6 @@ struct Cli {
     #[arg(long = "echo", value_name = "TOPIC", global = true)]
     echo_topics: Vec<String>,
 
-    /// Deprecated: use `hu web`. Start the web plugin server (default port 8080).
-    #[arg(long, value_name = "PORT", global = true, hide = true)]
-    web: Option<Option<u16>>,
-
     #[command(subcommand)]
     command: Option<Commands>,
 }
@@ -185,29 +177,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
         Some(Commands::External(args)) => run_cli_frontend(args, core, &router).await?,
         // Plugin/Router are handled and returned above.
         Some(Commands::Plugin { .. }) | Some(Commands::Router { .. }) => unreachable!(),
-        // Default + the deprecated --export / --web / --headless flags.
+        // Default: bare `hu`, plus the deprecated `--export` flag.
         None => {
             if let Some(path) = cli.export {
                 frontend::launch(frontend::Export { path }, core, &router).await?
-            } else if let Some(port) = cli.web {
-                frontend::launch(
-                    frontend::Web {
-                        port: port.unwrap_or(8080),
-                    },
-                    core,
-                    &router,
-                )
-                .await?
-            } else if cli.headless {
-                frontend::launch(
-                    frontend::Stream {
-                        json: cli.json,
-                        echo: cli.echo_topics,
-                    },
-                    core,
-                    &router,
-                )
-                .await?
             } else {
                 frontend::launch(frontend::Tui, core, &router).await?
             }

crates/hiroz-union/src/modes/cli.rs

@@ -69,9 +69,7 @@ pub async fn run_cli_plugin(
             .await;
     }
 
-    let exit_code = plugin
-        .dispatch_cli_event(CliEvent::Startup(args))
-        .exit_code();
+    let exit_code = plugin.dispatch_cli_event(CliEvent::Startup(args));
     flush_output(plugin);
     if let Some(code) = exit_code {
         return Ok(code);
@@ -91,7 +89,7 @@ pub async fn run_cli_plugin(
     // a Tick.
     if raw_tick_ms == 0 {
         let _ = sigint_rx.await;
-        let interrupt_code = plugin.dispatch_cli_event(CliEvent::Interrupt).exit_code();
+        let interrupt_code = plugin.dispatch_cli_event(CliEvent::Interrupt);
         flush_output(plugin);
         return Ok(interrupt_code.unwrap_or(130));
     }
@@ -101,19 +99,19 @@ pub async fn run_cli_plugin(
 
     loop {
         if sigint_rx.try_recv().is_ok() {
-            let interrupt_code = plugin.dispatch_cli_event(CliEvent::Interrupt).exit_code();
+            let interrupt_code = plugin.dispatch_cli_event(CliEvent::Interrupt);
             flush_output(plugin);
             if let Some(code) = interrupt_code {
                 return Ok(code);
             }
-            let code = plugin.dispatch_cli_event(CliEvent::Tick).exit_code();
+            let code = plugin.dispatch_cli_event(CliEvent::Tick);
             flush_output(plugin);
             return Ok(code.unwrap_or(130));
         }
 
         tokio::time::sleep(tick_interval).await;
 
-        let code = plugin.dispatch_cli_event(CliEvent::Tick).exit_code();
+        let code = plugin.dispatch_cli_event(CliEvent::Tick);
         flush_output(plugin);
         if let Some(c) = code {
             return Ok(c);

crates/hiroz-union/src/plugin/wasm/host/mod.rs

@@ -7,10 +7,11 @@ pub mod transport;
 
 use wasmtime::component::bindgen;
 
-// Legacy / TUI world — used for backward compat and for instantiating hu-plugin
-// (v0.3) components. All Host trait impls on PluginState live here.
+// TUI world — this bindgen also generates the shared `hu::plugin::*` interface
+// modules and their Host traits, which the CLI and web worlds below reuse via
+// `with:` directives. All Host trait impls on PluginState live here.
 bindgen!({
-    world: "hu-plugin",
+    world: "hu-tui-plugin",
     path: "wit/v0.1/hu-plugin.wit",
 });
 
@@ -32,24 +33,6 @@ pub mod cli_bindgen {
     });
 }
 
-/// TUI-world bindings (new hu-tui-plugin world — same interfaces as legacy
-/// hu-plugin but exports on-event(tui-event) instead of on-event(plugin-event)).
-pub mod tui_bindgen {
-    use wasmtime::component::bindgen;
-    bindgen!({
-        world: "hu-tui-plugin",
-        path: "wit/v0.1/hu-plugin.wit",
-        with: {
-            "hu:plugin/types":         super::hu::plugin::types,
-            "hu:plugin/graph":         super::hu::plugin::graph,
-            "hu:plugin/ros":           super::hu::plugin::ros,
-            "hu:plugin/render":        super::hu::plugin::render,
-            "hu:plugin/raw-transport": super::hu::plugin::raw_transport,
-            "hu:plugin/session":       super::hu::plugin::session,
-        }
-    });
-}
-
 /// Web-world bindings.  Only imports graph and ros (no TUI render interface).
 pub mod web_bindgen {
     use wasmtime::component::bindgen;