refactor(plugins): fix plugin loading data flow (#1995)

zellij-server/src/lib.rs

@@ -4,6 +4,7 @@ pub mod panes;
 pub mod tab;
 
 mod logging_pipe;
+mod plugins;
 mod pty;
 mod pty_writer;
 mod route;
@@ -11,7 +12,6 @@ mod screen;
 mod terminal_bytes;
 mod thread_bus;
 mod ui;
-mod wasm_vm;
 
 use log::info;
 use pty_writer::{pty_writer_main, PtyWriteInstruction};
@@ -29,10 +29,10 @@ use wasmer::Store;
 
 use crate::{
     os_input_output::ServerOsApi,
+    plugins::{plugin_thread_main, PluginInstruction},
     pty::{pty_thread_main, Pty, PtyInstruction},
     screen::{screen_thread_main, ScreenInstruction},
     thread_bus::{Bus, ThreadSenders},
-    wasm_vm::{wasm_thread_main, PluginInstruction},
 };
 use route::route_thread_main;
 use zellij_utils::{
@@ -108,7 +108,7 @@ pub(crate) struct SessionMetaData {
     pub default_shell: Option<TerminalAction>,
     screen_thread: Option<thread::JoinHandle<()>>,
     pty_thread: Option<thread::JoinHandle<()>>,
-    wasm_thread: Option<thread::JoinHandle<()>>,
+    plugin_thread: Option<thread::JoinHandle<()>>,
     pty_writer_thread: Option<thread::JoinHandle<()>>,
 }
 
@@ -124,8 +124,8 @@ impl Drop for SessionMetaData {
         if let Some(pty_thread) = self.pty_thread.take() {
             let _ = pty_thread.join();
         }
-        if let Some(wasm_thread) = self.wasm_thread.take() {
-            let _ = wasm_thread.join();
+        if let Some(plugin_thread) = self.plugin_thread.take() {
+            let _ = plugin_thread.join();
         }
         if let Some(pty_writer_thread) = self.pty_writer_thread.take() {
             let _ = pty_writer_thread.join();
@@ -332,7 +332,7 @@ pub fn start_server(mut os_input: Box<dyn ServerOsApi>, socket_path: PathBuf) {
                         .as_ref()
                         .unwrap()
                         .senders
-                        .send_to_pty(PtyInstruction::NewTab(
+                        .send_to_screen(ScreenInstruction::NewTab(
                             default_shell.clone(),
                             tab_layout,
                             tab_name,
@@ -655,6 +655,7 @@ fn init_session(
     let pty_thread = thread::Builder::new()
         .name("pty".to_string())
         .spawn({
+            let layout = layout.clone();
             let pty = Pty::new(
                 Bus::new(
                     vec![pty_receiver],
@@ -700,7 +701,7 @@ fn init_session(
         })
         .unwrap();
 
-    let wasm_thread = thread::Builder::new()
+    let plugin_thread = thread::Builder::new()
         .name("wasm".to_string())
         .spawn({
             let plugin_bus = Bus::new(
@@ -715,7 +716,14 @@ fn init_session(
             let store = Store::default();
 
             move || {
-                wasm_thread_main(plugin_bus, store, data_dir, plugins.unwrap_or_default()).fatal()
+                plugin_thread_main(
+                    plugin_bus,
+                    store,
+                    data_dir,
+                    plugins.unwrap_or_default(),
+                    layout,
+                )
+                .fatal()
             }
         })
         .unwrap();
@@ -750,7 +758,7 @@ fn init_session(
         client_attributes,
         screen_thread: Some(screen_thread),
         pty_thread: Some(pty_thread),
-        wasm_thread: Some(wasm_thread),
+        plugin_thread: Some(plugin_thread),
         pty_writer_thread: Some(pty_writer_thread),
     }
 }

zellij-server/src/panes/floating_panes/mod.rs

@@ -9,9 +9,9 @@ use crate::{
     os_input_output::ServerOsApi,
     output::{FloatingPanesStack, Output},
     panes::{ActivePanes, PaneId},
+    plugins::PluginInstruction,
     thread_bus::ThreadSenders,
     ui::pane_contents_and_ui::PaneContentsAndUi,
-    wasm_vm::PluginInstruction,
     ClientId,
 };
 use std::cell::RefCell;

zellij-server/src/panes/plugin_pane.rs

@@ -3,10 +3,10 @@ use std::time::Instant;
 
 use crate::output::{CharacterChunk, SixelImageChunk};
 use crate::panes::{grid::Grid, sixel::SixelImageStore, LinkHandler, PaneId};
+use crate::plugins::PluginInstruction;
 use crate::pty::VteBytes;
 use crate::tab::Pane;
 use crate::ui::pane_boundaries_frame::{FrameParams, PaneFrame};
-use crate::wasm_vm::PluginInstruction;
 use crate::ClientId;
 use std::cell::RefCell;
 use std::rc::Rc;

zellij-server/src/panes/tiled_panes/mod.rs

@@ -8,11 +8,11 @@ use crate::{
     os_input_output::ServerOsApi,
     output::Output,
     panes::{ActivePanes, PaneId},
+    plugins::PluginInstruction,
     tab::{Pane, MIN_TERMINAL_HEIGHT, MIN_TERMINAL_WIDTH},
     thread_bus::ThreadSenders,
     ui::boundaries::Boundaries,
     ui::pane_contents_and_ui::PaneContentsAndUi,
-    wasm_vm::PluginInstruction,
     ClientId,
 };
 use zellij_utils::{
@@ -346,9 +346,7 @@ impl TiledPanes {
         self.reset_boundaries();
     }
     pub fn focus_pane_if_client_not_focused(&mut self, pane_id: PaneId, client_id: ClientId) {
-        log::info!("inside focus_pane_if_client_not_focused");
         if self.active_panes.get(&client_id).is_none() {
-            log::info!("is none");
             self.focus_pane(pane_id, client_id)
         }
     }

zellij-server/src/plugins/mod.rs

@@ -0,0 +1,135 @@
+mod wasm_bridge;
+use log::info;
+use std::{collections::HashMap, fs, path::PathBuf};
+use wasmer::Store;
+
+use crate::{pty::PtyInstruction, thread_bus::Bus, ClientId};
+
+use wasm_bridge::WasmBridge;
+
+use zellij_utils::{
+    data::Event,
+    errors::{prelude::*, ContextType, PluginContext},
+    input::{
+        command::TerminalAction,
+        layout::{Layout, PaneLayout, Run, RunPlugin, RunPluginLocation},
+        plugins::PluginsConfig,
+    },
+    pane_size::Size,
+};
+
+#[derive(Clone, Debug)]
+pub enum PluginInstruction {
+    Load(RunPlugin, usize, ClientId, Size), // plugin metadata, tab_index, client_ids
+    Update(Option<u32>, Option<ClientId>, Event), // Focused plugin / broadcast, client_id, event data
+    Unload(u32),                                  // plugin_id
+    Resize(u32, usize, usize),                    // plugin_id, columns, rows
+    AddClient(ClientId),
+    RemoveClient(ClientId),
+    NewTab(
+        Option<TerminalAction>,
+        Option<PaneLayout>,
+        Option<String>, // tab name
+        usize,          // tab_index
+        ClientId,
+    ),
+    Exit,
+}
+
+impl From<&PluginInstruction> for PluginContext {
+    fn from(plugin_instruction: &PluginInstruction) -> Self {
+        match *plugin_instruction {
+            PluginInstruction::Load(..) => PluginContext::Load,
+            PluginInstruction::Update(..) => PluginContext::Update,
+            PluginInstruction::Unload(..) => PluginContext::Unload,
+            PluginInstruction::Resize(..) => PluginContext::Resize,
+            PluginInstruction::Exit => PluginContext::Exit,
+            PluginInstruction::AddClient(_) => PluginContext::AddClient,
+            PluginInstruction::RemoveClient(_) => PluginContext::RemoveClient,
+            PluginInstruction::NewTab(..) => PluginContext::NewTab,
+        }
+    }
+}
+
+pub(crate) fn plugin_thread_main(
+    bus: Bus<PluginInstruction>,
+    store: Store,
+    data_dir: PathBuf,
+    plugins: PluginsConfig,
+    layout: Box<Layout>,
+) -> Result<()> {
+    info!("Wasm main thread starts");
+
+    let plugin_dir = data_dir.join("plugins/");
+    let plugin_global_data_dir = plugin_dir.join("data");
+
+    let mut wasm_bridge = WasmBridge::new(plugins, bus.senders.clone(), store, plugin_dir);
+
+    loop {
+        let (event, mut err_ctx) = bus.recv().expect("failed to receive event on channel");
+        err_ctx.add_call(ContextType::Plugin((&event).into()));
+        match event {
+            // TODO: remove pid_tx from here
+            PluginInstruction::Load(run, tab_index, client_id, size) => {
+                wasm_bridge.load_plugin(&run, tab_index, size, client_id)?;
+            },
+            PluginInstruction::Update(pid, cid, event) => {
+                wasm_bridge.update_plugins(pid, cid, event)?;
+            },
+            PluginInstruction::Unload(pid) => {
+                wasm_bridge.unload_plugin(pid)?;
+            },
+            PluginInstruction::Resize(pid, new_columns, new_rows) => {
+                wasm_bridge.resize_plugin(pid, new_columns, new_rows)?;
+            },
+            PluginInstruction::AddClient(client_id) => {
+                wasm_bridge.add_client(client_id)?;
+            },
+            PluginInstruction::RemoveClient(client_id) => {
+                wasm_bridge.remove_client(client_id);
+            },
+            PluginInstruction::NewTab(
+                terminal_action,
+                tab_layout,
+                tab_name,
+                tab_index,
+                client_id,
+            ) => {
+                let mut plugin_ids: HashMap<RunPluginLocation, Vec<u32>> = HashMap::new();
+                let extracted_run_instructions = tab_layout
+                    .clone()
+                    .unwrap_or_else(|| layout.new_tab())
+                    .extract_run_instructions();
+                let size = Size::default(); // TODO: is this bad?
+                for run_instruction in extracted_run_instructions {
+                    if let Some(Run::Plugin(run)) = run_instruction {
+                        let plugin_id =
+                            wasm_bridge.load_plugin(&run, tab_index, size, client_id)?;
+                        plugin_ids.entry(run.location).or_default().push(plugin_id);
+                    }
+                }
+                drop(bus.senders.send_to_pty(PtyInstruction::NewTab(
+                    terminal_action,
+                    tab_layout,
+                    tab_name,
+                    tab_index,
+                    plugin_ids,
+                    client_id,
+                )));
+            },
+            PluginInstruction::Exit => break,
+        }
+    }
+    info!("wasm main thread exits");
+
+    fs::remove_dir_all(&plugin_global_data_dir)
+        .or_else(|err| {
+            if err.kind() == std::io::ErrorKind::NotFound {
+                // I don't care...
+                Ok(())
+            } else {
+                Err(err)
+            }
+        })
+        .context("failed to cleanup plugin data directory")
+}

zellij-server/src/plugins/wasm_bridge.rs

@@ -0,0 +1,737 @@
+use super::PluginInstruction;
+use highway::{HighwayHash, PortableHash};
+use log::{debug, info, warn};
+use semver::Version;
+use serde::{de::DeserializeOwned, Serialize};
+use std::{
+    collections::{HashMap, HashSet},
+    fmt, fs,
+    path::PathBuf,
+    process,
+    str::FromStr,
+    sync::{Arc, Mutex},
+    thread,
+    time::{Duration, Instant},
+};
+use url::Url;
+use wasmer::{
+    imports, ChainableNamedResolver, Function, ImportObject, Instance, Module, Store, Value,
+    WasmerEnv,
+};
+use wasmer_wasi::{Pipe, WasiEnv, WasiState};
+
+use crate::{
+    logging_pipe::LoggingPipe,
+    panes::PaneId,
+    pty::{ClientOrTabIndex, PtyInstruction},
+    screen::ScreenInstruction,
+    thread_bus::ThreadSenders,
+    ClientId,
+};
+
+use zellij_utils::{
+    consts::{DEBUG_MODE, VERSION, ZELLIJ_CACHE_DIR, ZELLIJ_TMP_DIR},
+    data::{Event, EventType, PluginIds},
+    errors::prelude::*,
+    input::{
+        command::TerminalAction,
+        layout::RunPlugin,
+        plugins::{PluginConfig, PluginType, PluginsConfig},
+    },
+    pane_size::Size,
+    serde,
+};
+
+/// Custom error for plugin version mismatch.
+///
+/// This is thrown when, during starting a plugin, it is detected that the plugin version doesn't
+/// match the zellij version. This is treated as a fatal error and leads to instantaneous
+/// termination.
+#[derive(Debug)]
+pub struct VersionMismatchError {
+    zellij_version: String,
+    plugin_version: String,
+    plugin_path: PathBuf,
+    // true for builtin plugins
+    builtin: bool,
+}
+
+impl std::error::Error for VersionMismatchError {}
+
+impl VersionMismatchError {
+    pub fn new(
+        zellij_version: &str,
+        plugin_version: &str,
+        plugin_path: &PathBuf,
+        builtin: bool,
+    ) -> Self {
+        VersionMismatchError {
+            zellij_version: zellij_version.to_owned(),
+            plugin_version: plugin_version.to_owned(),
+            plugin_path: plugin_path.to_owned(),
+            builtin,
+        }
+    }
+}
+
+impl fmt::Display for VersionMismatchError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let first_line = if self.builtin {
+            "It seems your version of zellij was built with outdated core plugins."
+        } else {
+            "If you're seeing this error a plugin version doesn't match the current
+zellij version."
+        };
+
+        write!(
+            f,
+            "{}
+Detected versions:
+
+- Plugin version: {}
+- Zellij version: {}
+- Offending plugin: {}
+
+If you're a user:
+    Please contact the distributor of your zellij version and report this error
+    to them.
+
+If you're a developer:
+    Please run zellij with updated plugins. The easiest way to achieve this
+    is to build zellij with `cargo make install`. Also refer to the docs:
+    https://github.com/zellij-org/zellij/blob/main/CONTRIBUTING.md#building
+",
+            first_line,
+            self.plugin_version.trim_end(),
+            self.zellij_version.trim_end(),
+            self.plugin_path.display()
+        )
+    }
+}
+
+#[derive(WasmerEnv, Clone)]
+pub struct PluginEnv {
+    pub plugin_id: u32,
+    pub plugin: PluginConfig,
+    pub senders: ThreadSenders,
+    pub wasi_env: WasiEnv,
+    pub subscriptions: Arc<Mutex<HashSet<EventType>>>,
+    pub tab_index: usize,
+    pub client_id: ClientId,
+    #[allow(dead_code)]
+    plugin_own_data_dir: PathBuf,
+}
+
+type PluginMap = HashMap<(u32, ClientId), (Instance, PluginEnv, (usize, usize))>; // u32 =>
+                                                                                  // plugin_id,
+                                                                                  // (usize, usize)
+                                                                                  // => (rows,
+                                                                                  // columns)
+
+pub struct WasmBridge {
+    connected_clients: Vec<ClientId>,
+    plugins: PluginsConfig,
+    senders: ThreadSenders,
+    store: Store,
+    plugin_dir: PathBuf,
+    plugin_cache: HashMap<PathBuf, Module>,
+    plugin_map: PluginMap,
+    next_plugin_id: u32,
+}
+
+impl WasmBridge {
+    pub fn new(
+        plugins: PluginsConfig,
+        senders: ThreadSenders,
+        store: Store,
+        plugin_dir: PathBuf,
+    ) -> Self {
+        let plugin_map = HashMap::new();
+        let connected_clients: Vec<ClientId> = vec![];
+        let plugin_cache: HashMap<PathBuf, Module> = HashMap::new();
+        WasmBridge {
+            connected_clients,
+            plugins,
+            senders,
+            store,
+            plugin_dir,
+            plugin_cache,
+            plugin_map,
+            next_plugin_id: 0,
+        }
+    }
+    pub fn load_plugin(
+        &mut self,
+        run: &RunPlugin,
+        tab_index: usize,
+        size: Size,
+        client_id: ClientId,
+    ) -> Result<u32> {
+        // returns the plugin id
+        let err_context = || format!("failed to load plugin for client {client_id}");
+        let plugin_id = self.next_plugin_id;
+
+        let plugin = self
+            .plugins
+            .get(run)
+            .with_context(|| format!("failed to resolve plugin {run:?}"))
+            .with_context(err_context)
+            .fatal();
+
+        let (instance, plugin_env) = self
+            .start_plugin(plugin_id, client_id, &plugin, tab_index)
+            .with_context(err_context)?;
+
+        let mut main_user_instance = instance.clone();
+        let main_user_env = plugin_env.clone();
+        load_plugin_instance(&mut main_user_instance).with_context(err_context)?;
+
+        self.plugin_map.insert(
+            (plugin_id, client_id),
+            (main_user_instance, main_user_env, (size.rows, size.cols)),
+        );
+
+        // clone plugins for the rest of the client ids if they exist
+        for client_id in self.connected_clients.iter() {
+            let mut new_plugin_env = plugin_env.clone();
+            new_plugin_env.client_id = *client_id;
+            let module = instance.module().clone();
+            let wasi = new_plugin_env
+                .wasi_env
+                .import_object(&module)
+                .with_context(err_context)?;
+            let zellij = zellij_exports(&self.store, &new_plugin_env);
+            let mut instance =
+                Instance::new(&module, &zellij.chain_back(wasi)).with_context(err_context)?;
+            load_plugin_instance(&mut instance).with_context(err_context)?;
+            self.plugin_map.insert(
+                (plugin_id, *client_id),
+                (instance, new_plugin_env, (size.rows, size.cols)),
+            );
+        }
+        self.next_plugin_id += 1;
+        Ok(plugin_id)
+    }
+    pub fn unload_plugin(&mut self, pid: u32) -> Result<()> {
+        info!("Bye from plugin {}", &pid);
+        // TODO: remove plugin's own data directory
+        let ids_in_plugin_map: Vec<(u32, ClientId)> = self.plugin_map.keys().copied().collect();
+        for (plugin_id, client_id) in ids_in_plugin_map {
+            if pid == plugin_id {
+                drop(self.plugin_map.remove(&(plugin_id, client_id)));
+            }
+        }
+        Ok(())
+    }
+    #[allow(clippy::too_many_arguments)]
+    pub fn start_plugin(
+        &mut self,
+        plugin_id: u32,
+        client_id: ClientId,
+        plugin: &PluginConfig,
+        tab_index: usize,
+    ) -> Result<(Instance, PluginEnv)> {
+        let err_context = || format!("failed to start plugin {plugin:#?} for client {client_id}");
+
+        let plugin_own_data_dir = ZELLIJ_CACHE_DIR.join(Url::from(&plugin.location).to_string());
+        let cache_hit = self.plugin_cache.contains_key(&plugin.path);
+
+        // We remove the entry here and repopulate it at the very bottom, if everything went well.
+        // We must do that because a `get` will only give us a borrow of the Module. This suffices for
+        // the purpose of setting everything up, but we cannot return a &Module from the "None" match
+        // arm, because we create the Module from scratch there. Any reference passed outside would
+        // outlive the Module we create there. Hence, we remove the plugin here and reinsert it
+        // below...
+        let module = match self.plugin_cache.remove(&plugin.path) {
+            Some(module) => {
+                log::debug!(
+                    "Loaded plugin '{}' from plugin cache",
+                    plugin.path.display()
+                );
+                module
+            },
+            None => {
+                // Populate plugin module cache for this plugin!
+                // Is it in the cache folder already?
+                if plugin._allow_exec_host_cmd {
+                    info!(
+                        "Plugin({:?}) is able to run any host command, this may lead to some security issues!",
+                        plugin.path
+                    );
+                }
+
+                // The plugins blob as stored on the filesystem
+                let wasm_bytes = plugin
+                    .resolve_wasm_bytes(&self.plugin_dir)
+                    .with_context(err_context)
+                    .fatal();
+
+                fs::create_dir_all(&plugin_own_data_dir)
+                    .with_context(|| format!("failed to create datadir in {plugin_own_data_dir:?}"))
+                    .with_context(err_context)
+                    .non_fatal();
+
+                // ensure tmp dir exists, in case it somehow was deleted (e.g systemd-tmpfiles)
+                fs::create_dir_all(ZELLIJ_TMP_DIR.as_path())
+                    .with_context(|| {
+                        format!("failed to create tmpdir at {:?}", &ZELLIJ_TMP_DIR.as_path())
+                    })
+                    .with_context(err_context)
+                    .non_fatal();
+
+                let hash: String = PortableHash::default()
+                    .hash256(&wasm_bytes)
+                    .iter()
+                    .map(ToString::to_string)
+                    .collect();
+                let cached_path = ZELLIJ_CACHE_DIR.join(&hash);
+
+                unsafe {
+                    match Module::deserialize_from_file(&self.store, &cached_path) {
+                        Ok(m) => {
+                            log::debug!(
+                                "Loaded plugin '{}' from cache folder at '{}'",
+                                plugin.path.display(),
+                                ZELLIJ_CACHE_DIR.display(),
+                            );
+                            m
+                        },
+                        Err(e) => {
+                            let inner_context = || format!("failed to recover from {e:?}");
+
+                            let m = Module::new(&self.store, &wasm_bytes)
+                                .with_context(inner_context)
+                                .with_context(err_context)?;
+                            fs::create_dir_all(ZELLIJ_CACHE_DIR.to_owned())
+                                .with_context(inner_context)
+                                .with_context(err_context)?;
+                            m.serialize_to_file(&cached_path)
+                                .with_context(inner_context)
+                                .with_context(err_context)?;
+                            m
+                        },
+                    }
+                }
+            },
+        };
+
+        let mut wasi_env = WasiState::new("Zellij")
+            .env("CLICOLOR_FORCE", "1")
+            .map_dir("/host", ".")
+            .and_then(|wasi| wasi.map_dir("/data", &plugin_own_data_dir))
+            .and_then(|wasi| wasi.map_dir("/tmp", ZELLIJ_TMP_DIR.as_path()))
+            .and_then(|wasi| {
+                wasi.stdin(Box::new(Pipe::new()))
+                    .stdout(Box::new(Pipe::new()))
+                    .stderr(Box::new(LoggingPipe::new(
+                        &plugin.location.to_string(),
+                        plugin_id,
+                    )))
+                    .finalize()
+            })
+            .with_context(err_context)?;
+        let wasi = wasi_env.import_object(&module).with_context(err_context)?;
+
+        let mut mut_plugin = plugin.clone();
+        mut_plugin.set_tab_index(tab_index);
+        let plugin_env = PluginEnv {
+            plugin_id,
+            client_id,
+            plugin: mut_plugin,
+            senders: self.senders.clone(),
+            wasi_env,
+            subscriptions: Arc::new(Mutex::new(HashSet::new())),
+            plugin_own_data_dir,
+            tab_index,
+        };
+
+        let zellij = zellij_exports(&self.store, &plugin_env);
+        let instance =
+            Instance::new(&module, &zellij.chain_back(wasi)).with_context(err_context)?;
+
+        if !cache_hit {
+            // Check plugin version
+            assert_plugin_version(&instance, &plugin_env).with_context(err_context)?;
+        }
+
+        // Only do an insert when everything went well!
+        let cloned_plugin = plugin.clone();
+        self.plugin_cache.insert(cloned_plugin.path, module);
+
+        Ok((instance, plugin_env))
+    }
+    pub fn add_client(&mut self, client_id: ClientId) -> Result<()> {
+        let err_context = || format!("failed to add plugins for client {client_id}");
+
+        self.connected_clients.push(client_id);
+
+        let mut seen = HashSet::new();
+        let mut new_plugins = HashMap::new();
+        for (&(plugin_id, _), (instance, plugin_env, (rows, columns))) in &self.plugin_map {
+            if seen.contains(&plugin_id) {
+                continue;
+            }
+            seen.insert(plugin_id);
+            let mut new_plugin_env = plugin_env.clone();
+
+            new_plugin_env.client_id = client_id;
+            new_plugins.insert(
+                plugin_id,
+                (instance.module().clone(), new_plugin_env, (*rows, *columns)),
+            );
+        }
+        for (plugin_id, (module, mut new_plugin_env, (rows, columns))) in new_plugins.drain() {
+            let wasi = new_plugin_env
+                .wasi_env
+                .import_object(&module)
+                .with_context(err_context)?;
+            let zellij = zellij_exports(&self.store, &new_plugin_env);
+            let mut instance =
+                Instance::new(&module, &zellij.chain_back(wasi)).with_context(err_context)?;
+            load_plugin_instance(&mut instance).with_context(err_context)?;
+            self.plugin_map.insert(
+                (plugin_id, client_id),
+                (instance, new_plugin_env, (rows, columns)),
+            );
+        }
+        Ok(())
+    }
+    pub fn resize_plugin(&mut self, pid: u32, new_columns: usize, new_rows: usize) -> Result<()> {
+        let err_context = || format!("failed to resize plugin {pid}");
+        for ((plugin_id, client_id), (instance, plugin_env, (current_rows, current_columns))) in
+            self.plugin_map.iter_mut()
+        {
+            if *plugin_id == pid {
+                *current_rows = new_rows;
+                *current_columns = new_columns;
+
+                // TODO: consolidate with above render function
+                let render = instance
+                    .exports
+                    .get_function("render")
+                    .with_context(err_context)?;
+
+                render
+                    .call(&[
+                        Value::I32(*current_rows as i32),
+                        Value::I32(*current_columns as i32),
+                    ])
+                    .with_context(err_context)?;
+                let rendered_bytes = wasi_read_string(&plugin_env.wasi_env);
+                drop(self.senders.send_to_screen(ScreenInstruction::PluginBytes(
+                    *plugin_id,
+                    *client_id,
+                    rendered_bytes.as_bytes().to_vec(),
+                )));
+            }
+        }
+        Ok(())
+    }
+    pub fn update_plugins(
+        &mut self,
+        pid: Option<u32>,
+        cid: Option<ClientId>,
+        event: Event,
+    ) -> Result<()> {
+        let err_context = || {
+            if *DEBUG_MODE.get().unwrap_or(&true) {
+                format!("failed to update plugin state with event: {event:#?}")
+            } else {
+                "failed to update plugin state".to_string()
+            }
+        };
+
+        for (&(plugin_id, client_id), (instance, plugin_env, (rows, columns))) in &self.plugin_map {
+            let subs = plugin_env
+                .subscriptions
+                .lock()
+                .to_anyhow()
+                .with_context(err_context)?;
+            // FIXME: This is very janky... Maybe I should write my own macro for Event -> EventType?
+            let event_type = EventType::from_str(&event.to_string()).with_context(err_context)?;
+            if subs.contains(&event_type)
+                && ((pid.is_none() && cid.is_none())
+                    || (pid.is_none() && cid == Some(client_id))
+                    || (cid.is_none() && pid == Some(plugin_id))
+                    || (cid == Some(client_id) && pid == Some(plugin_id)))
+            {
+                let update = instance
+                    .exports
+                    .get_function("update")
+                    .with_context(err_context)?;
+                wasi_write_object(&plugin_env.wasi_env, &event);
+                let update_return = update.call(&[]).or_else::<anyError, _>(|e| {
+                    match e.downcast::<serde_json::Error>() {
+                        Ok(_) => panic!(
+                            "{}",
+                            anyError::new(VersionMismatchError::new(
+                                VERSION,
+                                "Unavailable",
+                                &plugin_env.plugin.path,
+                                plugin_env.plugin.is_builtin(),
+                            ))
+                        ),
+                        Err(e) => Err(e).with_context(err_context),
+                    }
+                })?;
+                let should_render = match update_return.get(0) {
+                    Some(Value::I32(n)) => *n == 1,
+                    _ => false,
+                };
+
+                if *rows > 0 && *columns > 0 && should_render {
+                    let render = instance
+                        .exports
+                        .get_function("render")
+                        .with_context(err_context)?;
+                    render
+                        .call(&[Value::I32(*rows as i32), Value::I32(*columns as i32)])
+                        .with_context(err_context)?;
+                    let rendered_bytes = wasi_read_string(&plugin_env.wasi_env);
+                    drop(self.senders.send_to_screen(ScreenInstruction::PluginBytes(
+                        plugin_id,
+                        client_id,
+                        rendered_bytes.as_bytes().to_vec(),
+                    )));
+                }
+            }
+        }
+        Ok(())
+    }
+    pub fn remove_client(&mut self, client_id: ClientId) {
+        self.connected_clients.retain(|c| c != &client_id);
+    }
+}
+
+// Returns `Ok` if the plugin version matches the zellij version.
+// Returns an `Err` otherwise.
+fn assert_plugin_version(instance: &Instance, plugin_env: &PluginEnv) -> Result<()> {
+    let err_context = || {
+        format!(
+            "failed to determine plugin version for plugin {}",
+            plugin_env.plugin.path.display()
+        )
+    };
+
+    let plugin_version_func = match instance.exports.get_function("plugin_version") {
+        Ok(val) => val,
+        Err(_) => {
+            return Err(anyError::new(VersionMismatchError::new(
+                VERSION,
+                "Unavailable",
+                &plugin_env.plugin.path,
+                plugin_env.plugin.is_builtin(),
+            )))
+        },
+    };
+    plugin_version_func.call(&[]).with_context(err_context)?;
+    let plugin_version_str = wasi_read_string(&plugin_env.wasi_env);
+    let plugin_version = Version::parse(&plugin_version_str)
+        .context("failed to parse plugin version")
+        .with_context(err_context)?;
+    let zellij_version = Version::parse(VERSION)
+        .context("failed to parse zellij version")
+        .with_context(err_context)?;
+    if plugin_version != zellij_version {
+        return Err(anyError::new(VersionMismatchError::new(
+            VERSION,
+            &plugin_version_str,
+            &plugin_env.plugin.path,
+            plugin_env.plugin.is_builtin(),
+        )));
+    }
+
+    Ok(())
+}
+
+fn load_plugin_instance(instance: &mut Instance) -> Result<()> {
+    let err_context = || format!("failed to load plugin from instance {instance:#?}");
+
+    let load_function = instance
+        .exports
+        .get_function("_start")
+        .with_context(err_context)?;
+    // This eventually calls the `.load()` method
+    load_function.call(&[]).with_context(err_context)?;
+    Ok(())
+}
+
+pub(crate) fn zellij_exports(store: &Store, plugin_env: &PluginEnv) -> ImportObject {
+    macro_rules! zellij_export {
+        ($($host_function:ident),+ $(,)?) => {
+            imports! {
+                "zellij" => {
+                    $(stringify!($host_function) =>
+                        Function::new_native_with_env(store, plugin_env.clone(), $host_function),)+
+                }
+            }
+        }
+    }
+
+    zellij_export! {
+        host_subscribe,
+        host_unsubscribe,
+        host_set_selectable,
+        host_get_plugin_ids,
+        host_get_zellij_version,
+        host_open_file,
+        host_switch_tab_to,
+        host_set_timeout,
+        host_exec_cmd,
+        host_report_panic,
+    }
+}
+
+fn host_subscribe(plugin_env: &PluginEnv) {
+    let mut subscriptions = plugin_env.subscriptions.lock().unwrap();
+    let new: HashSet<EventType> = wasi_read_object(&plugin_env.wasi_env);
+    subscriptions.extend(new);
+}
+
+fn host_unsubscribe(plugin_env: &PluginEnv) {
+    let mut subscriptions = plugin_env.subscriptions.lock().unwrap();
+    let old: HashSet<EventType> = wasi_read_object(&plugin_env.wasi_env);
+    subscriptions.retain(|k| !old.contains(k));
+}
+
+fn host_set_selectable(plugin_env: &PluginEnv, selectable: i32) {
+    match plugin_env.plugin.run {
+        PluginType::Pane(Some(tab_index)) => {
+            let selectable = selectable != 0;
+            plugin_env
+                .senders
+                .send_to_screen(ScreenInstruction::SetSelectable(
+                    PaneId::Plugin(plugin_env.plugin_id),
+                    selectable,
+                    tab_index,
+                ))
+                .unwrap()
+        },
+        _ => {
+            debug!(
+                "{} - Calling method 'host_set_selectable' does nothing for headless plugins",
+                plugin_env.plugin.location
+            )
+        },
+    }
+}
+
+fn host_get_plugin_ids(plugin_env: &PluginEnv) {
+    let ids = PluginIds {
+        plugin_id: plugin_env.plugin_id,
+        zellij_pid: process::id(),
+    };
+    wasi_write_object(&plugin_env.wasi_env, &ids);
+}
+
+fn host_get_zellij_version(plugin_env: &PluginEnv) {
+    wasi_write_object(&plugin_env.wasi_env, VERSION);
+}
+
+fn host_open_file(plugin_env: &PluginEnv) {
+    let path: PathBuf = wasi_read_object(&plugin_env.wasi_env);
+    plugin_env
+        .senders
+        .send_to_pty(PtyInstruction::SpawnTerminal(
+            Some(TerminalAction::OpenFile(path, None)),
+            None,
+            None,
+            ClientOrTabIndex::TabIndex(plugin_env.tab_index),
+        ))
+        .unwrap();
+}
+
+fn host_switch_tab_to(plugin_env: &PluginEnv, tab_idx: u32) {
+    plugin_env
+        .senders
+        .send_to_screen(ScreenInstruction::GoToTab(
+            tab_idx,
+            Some(plugin_env.client_id),
+        ))
+        .unwrap();
+}
+
+fn host_set_timeout(plugin_env: &PluginEnv, secs: f64) {
+    // There is a fancy, high-performance way to do this with zero additional threads:
+    // If the plugin thread keeps a BinaryHeap of timer structs, it can manage multiple and easily `.peek()` at the
+    // next time to trigger in O(1) time. Once the wake-up time is known, the `wasm` thread can use `recv_timeout()`
+    // to wait for an event with the timeout set to be the time of the next wake up. If events come in in the meantime,
+    // they are handled, but if the timeout triggers, we replace the event from `recv()` with an
+    // `Update(pid, TimerEvent)` and pop the timer from the Heap (or reschedule it). No additional threads for as many
+    // timers as we'd like.
+    //
+    // But that's a lot of code, and this is a few lines:
+    let send_plugin_instructions = plugin_env.senders.to_plugin.clone();
+    let update_target = Some(plugin_env.plugin_id);
+    let client_id = plugin_env.client_id;
+    thread::spawn(move || {
+        let start_time = Instant::now();
+        thread::sleep(Duration::from_secs_f64(secs));
+        // FIXME: The way that elapsed time is being calculated here is not exact; it doesn't take into account the
+        // time it takes an event to actually reach the plugin after it's sent to the `wasm` thread.
+        let elapsed_time = Instant::now().duration_since(start_time).as_secs_f64();
+
+        send_plugin_instructions
+            .unwrap()
+            .send(PluginInstruction::Update(
+                update_target,
+                Some(client_id),
+                Event::Timer(elapsed_time),
+            ))
+            .unwrap();
+    });
+}
+
+fn host_exec_cmd(plugin_env: &PluginEnv) {
+    let mut cmdline: Vec<String> = wasi_read_object(&plugin_env.wasi_env);
+    let command = cmdline.remove(0);
+
+    // Bail out if we're forbidden to run command
+    if !plugin_env.plugin._allow_exec_host_cmd {
+        warn!("This plugin isn't allow to run command in host side, skip running this command: '{cmd} {args}'.",
+        	cmd = command, args = cmdline.join(" "));
+        return;
+    }
+
+    // Here, we don't wait the command to finish
+    process::Command::new(command)
+        .args(cmdline)
+        .spawn()
+        .unwrap();
+}
+
+// Custom panic handler for plugins.
+//
+// This is called when a panic occurs in a plugin. Since most panics will likely originate in the
+// code trying to deserialize an `Event` upon a plugin state update, we read some panic message,
+// formatted as string from the plugin.
+fn host_report_panic(plugin_env: &PluginEnv) {
+    let msg = wasi_read_string(&plugin_env.wasi_env);
+    panic!("{}", msg);
+}
+
+// Helper Functions ---------------------------------------------------------------------------------------------------
+
+pub fn wasi_read_string(wasi_env: &WasiEnv) -> String {
+    let mut state = wasi_env.state();
+    let wasi_file = state.fs.stdout_mut().unwrap().as_mut().unwrap();
+    let mut buf = String::new();
+    wasi_file.read_to_string(&mut buf).unwrap();
+    // https://stackoverflow.com/questions/66450942/in-rust-is-there-a-way-to-make-literal-newlines-in-r-using-windows-c
+    buf.replace("\n", "\n\r")
+}
+
+pub fn wasi_write_string(wasi_env: &WasiEnv, buf: &str) {
+    let mut state = wasi_env.state();
+    let wasi_file = state.fs.stdin_mut().unwrap().as_mut().unwrap();
+    writeln!(wasi_file, "{}\r", buf).unwrap();
+}
+
+pub fn wasi_write_object(wasi_env: &WasiEnv, object: &(impl Serialize + ?Sized)) {
+    wasi_write_string(wasi_env, &serde_json::to_string(&object).unwrap());
+}
+
+pub fn wasi_read_object<T: DeserializeOwned>(wasi_env: &WasiEnv) -> T {
+    let json = wasi_read_string(wasi_env);
+    serde_json::from_str(&json).unwrap()
+}

zellij-server/src/pty.rs

@@ -1,9 +1,9 @@
 use crate::terminal_bytes::TerminalBytes;
 use crate::{
     panes::PaneId,
+    plugins::PluginInstruction,
     screen::ScreenInstruction,
     thread_bus::{Bus, ThreadSenders},
-    wasm_vm::PluginInstruction,
     ClientId, ServerInstruction,
 };
 use async_std::task::{self, JoinHandle};
@@ -15,7 +15,7 @@ use zellij_utils::{
     errors::{ContextType, PtyContext},
     input::{
         command::{RunCommand, TerminalAction},
-        layout::{Layout, PaneLayout, Run},
+        layout::{Layout, PaneLayout, Run, RunPluginLocation},
     },
 };
 
@@ -51,6 +51,8 @@ pub enum PtyInstruction {
         Option<TerminalAction>,
         Option<PaneLayout>,
         Option<String>,
+        usize,                                // tab_index
+        HashMap<RunPluginLocation, Vec<u32>>, // plugin_ids
         ClientId,
     ), // the String is the tab name
     ClosePane(PaneId),
@@ -330,12 +332,21 @@ pub(crate) fn pty_thread_main(mut pty: Pty, layout: Box<Layout>) -> Result<()> {
                         format!("failed to move client {} to tab {}", client_id, tab_index)
                     })?;
             },
-            PtyInstruction::NewTab(terminal_action, tab_layout, tab_name, client_id) => {
+            PtyInstruction::NewTab(
+                terminal_action,
+                tab_layout,
+                tab_name,
+                tab_index,
+                plugin_ids,
+                client_id,
+            ) => {
                 let err_context = || format!("failed to open new tab for client {}", client_id);
 
                 pty.spawn_terminals_for_layout(
                     tab_layout.unwrap_or_else(|| layout.new_tab()),
                     terminal_action.clone(),
+                    plugin_ids,
+                    tab_index,
                     client_id,
                 )
                 .with_context(err_context)?;
@@ -555,6 +566,8 @@ impl Pty {
         &mut self,
         layout: PaneLayout,
         default_shell: Option<TerminalAction>,
+        plugin_ids: HashMap<RunPluginLocation, Vec<u32>>,
+        tab_index: usize,
         client_id: ClientId,
     ) -> Result<()> {
         let err_context = || format!("failed to spawn terminals for layout for client {client_id}");
@@ -747,9 +760,11 @@ impl Pty {
             .collect();
         self.bus
             .senders
-            .send_to_screen(ScreenInstruction::NewTab(
+            .send_to_screen(ScreenInstruction::ApplyLayout(
                 layout,
                 new_tab_pane_ids,
+                plugin_ids,
+                tab_index,
                 client_id,
             ))
             .with_context(err_context)?;

zellij-server/src/route.rs

@@ -2,9 +2,9 @@ use std::sync::{Arc, RwLock};
 
 use crate::{
     os_input_output::ServerOsApi,
+    plugins::PluginInstruction,
     pty::{ClientOrTabIndex, PtyInstruction},
     screen::ScreenInstruction,
-    wasm_vm::PluginInstruction,
     ServerInstruction, SessionMetaData, SessionState,
 };
 use zellij_utils::{
@@ -440,7 +440,7 @@ pub(crate) fn route_action(
             let shell = session.default_shell.clone();
             session
                 .senders
-                .send_to_pty(PtyInstruction::NewTab(
+                .send_to_screen(ScreenInstruction::NewTab(
                     shell, tab_layout, tab_name, client_id,
                 ))
                 .with_context(err_context)?;

zellij-server/src/screen.rs

@@ -9,7 +9,11 @@ use zellij_utils::errors::prelude::*;
 use zellij_utils::input::command::RunCommand;
 use zellij_utils::input::options::Clipboard;
 use zellij_utils::pane_size::{Size, SizeInPixels};
-use zellij_utils::{input::command::TerminalAction, input::layout::PaneLayout, position::Position};
+use zellij_utils::{
+    input::command::TerminalAction,
+    input::layout::{PaneLayout, RunPluginLocation},
+    position::Position,
+};
 
 use crate::panes::alacritty_functions::xparse_color;
 use crate::panes::terminal_character::AnsiCode;
@@ -18,11 +22,11 @@ use crate::{
     output::Output,
     panes::sixel::SixelImageStore,
     panes::PaneId,
+    plugins::PluginInstruction,
     pty::{ClientOrTabIndex, PtyInstruction, VteBytes},
     tab::Tab,
     thread_bus::Bus,
     ui::overlay::{Overlay, OverlayWindow, Overlayable},
-    wasm_vm::PluginInstruction,
     ClientId, ServerInstruction,
 };
 use zellij_utils::{
@@ -174,7 +178,19 @@ pub enum ScreenInstruction {
     HoldPane(PaneId, Option<i32>, RunCommand, Option<ClientId>), // Option<i32> is the exit status
     UpdatePaneName(Vec<u8>, ClientId),
     UndoRenamePane(ClientId),
-    NewTab(PaneLayout, Vec<(u32, HoldForCommand)>, ClientId),
+    NewTab(
+        Option<TerminalAction>,
+        Option<PaneLayout>,
+        Option<String>,
+        ClientId,
+    ),
+    ApplyLayout(
+        PaneLayout,
+        Vec<(u32, HoldForCommand)>,
+        HashMap<RunPluginLocation, Vec<u32>>,
+        usize, // tab_index
+        ClientId,
+    ),
     SwitchTabNext(ClientId),
     SwitchTabPrev(ClientId),
     ToggleActiveSyncTab(ClientId),
@@ -275,6 +291,7 @@ impl From<&ScreenInstruction> for ScreenContext {
             ScreenInstruction::UpdatePaneName(..) => ScreenContext::UpdatePaneName,
             ScreenInstruction::UndoRenamePane(..) => ScreenContext::UndoRenamePane,
             ScreenInstruction::NewTab(..) => ScreenContext::NewTab,
+            ScreenInstruction::ApplyLayout(..) => ScreenContext::ApplyLayout,
             ScreenInstruction::SwitchTabNext(..) => ScreenContext::SwitchTabNext,
             ScreenInstruction::SwitchTabPrev(..) => ScreenContext::SwitchTabPrev,
             ScreenInstruction::CloseTab(..) => ScreenContext::CloseTab,
@@ -761,7 +778,7 @@ impl Screen {
                 let vte_overlay = overlay.generate_overlay(size).context(err_context)?;
                 tab.render(&mut output, Some(vte_overlay))
                     .context(err_context)?;
-            } else {
+            } else if !tab.is_pending() {
                 tabs_to_close.push(*tab_index);
             }
         }
@@ -838,14 +855,8 @@ impl Screen {
         self.get_tabs_mut().get_mut(&tab_index)
     }
 
-    /// Creates a new [`Tab`] in this [`Screen`], applying the specified [`Layout`]
-    /// and switching to it.
-    pub fn new_tab(
-        &mut self,
-        layout: PaneLayout,
-        new_ids: Vec<(u32, HoldForCommand)>,
-        client_id: ClientId,
-    ) -> Result<()> {
+    /// Creates a new [`Tab`] in this [`Screen`]
+    pub fn new_tab(&mut self, tab_index: usize, client_id: ClientId) -> Result<()> {
         let err_context = || format!("failed to create new tab for client {client_id:?}",);
 
         let client_id = if self.get_active_tab(client_id).is_ok() {
@@ -856,9 +867,8 @@ impl Screen {
             client_id
         };
 
-        let tab_index = self.get_new_tab_index();
         let position = self.tabs.len();
-        let mut tab = Tab::new(
+        let tab = Tab::new(
             tab_index,
             position,
             String::new(),
@@ -882,35 +892,72 @@ impl Screen {
             self.terminal_emulator_colors.clone(),
             self.terminal_emulator_color_codes.clone(),
         );
-        tab.apply_layout(layout, new_ids, tab_index, client_id)
-            .with_context(err_context)?;
-        if self.session_is_mirrored {
-            if let Ok(active_tab) = self.get_active_tab_mut(client_id) {
-                let client_mode_infos_in_source_tab = active_tab.drain_connected_clients(None);
-                tab.add_multiple_clients(client_mode_infos_in_source_tab)
-                    .with_context(err_context)?;
-                if active_tab.has_no_connected_clients() {
-                    active_tab.visible(false).with_context(err_context)?;
-                }
-            }
+        self.tabs.insert(tab_index, tab);
+        Ok(())
+    }
+    pub fn apply_layout(
+        &mut self,
+        layout: PaneLayout,
+        new_terminal_ids: Vec<(u32, HoldForCommand)>,
+        new_plugin_ids: HashMap<RunPluginLocation, Vec<u32>>,
+        tab_index: usize,
+        client_id: ClientId,
+    ) -> Result<()> {
+        let client_id = if self.get_active_tab(client_id).is_ok() {
+            client_id
+        } else if let Some(first_client_id) = self.get_first_client_id() {
+            first_client_id
+        } else {
+            client_id
+        };
+        let err_context = || format!("failed to apply layout for tab {tab_index:?}",);
+
+        // move the relevant clients out of the current tab and place them in the new one
+        let drained_clients = if self.session_is_mirrored {
+            let client_mode_infos_in_source_tab =
+                if let Ok(active_tab) = self.get_active_tab_mut(client_id) {
+                    let client_mode_infos_in_source_tab = active_tab.drain_connected_clients(None);
+                    if active_tab.has_no_connected_clients() {
+                        active_tab.visible(false).with_context(err_context)?;
+                    }
+                    Some(client_mode_infos_in_source_tab)
+                } else {
+                    None
+                };
             let all_connected_clients: Vec<ClientId> =
                 self.connected_clients.borrow().iter().copied().collect();
             for client_id in all_connected_clients {
                 self.update_client_tab_focus(client_id, tab_index);
             }
+            client_mode_infos_in_source_tab
         } else if let Ok(active_tab) = self.get_active_tab_mut(client_id) {
             let client_mode_info_in_source_tab =
                 active_tab.drain_connected_clients(Some(vec![client_id]));
-            tab.add_multiple_clients(client_mode_info_in_source_tab)
-                .with_context(err_context)?;
             if active_tab.has_no_connected_clients() {
                 active_tab.visible(false).with_context(err_context)?;
             }
             self.update_client_tab_focus(client_id, tab_index);
-        }
+            Some(client_mode_info_in_source_tab)
+        } else {
+            None
+        };
+
+        // apply the layout to the new tab
+        let tab = self.tabs.get_mut(&tab_index).unwrap(); // TODO: no unwrap
+        tab.apply_layout(
+            layout,
+            new_terminal_ids,
+            new_plugin_ids,
+            tab_index,
+            client_id,
+        )
+        .with_context(err_context)?;
         tab.update_input_modes().with_context(err_context)?;
         tab.visible(true).with_context(err_context)?;
-        self.tabs.insert(tab_index, tab);
+        if let Some(drained_clients) = drained_clients {
+            tab.add_multiple_clients(drained_clients)
+                .with_context(err_context)?;
+        }
         if !self.active_tab_indices.contains_key(&client_id) {
             // this means this is a new client and we need to add it to our state properly
             self.add_client(client_id).with_context(err_context)?;
@@ -1853,8 +1900,28 @@ pub(crate) fn screen_thread_main(
                 screen.unblock_input()?;
                 screen.render()?;
             },
-            ScreenInstruction::NewTab(layout, new_pane_pids, client_id) => {
-                screen.new_tab(layout, new_pane_pids, client_id)?;
+            ScreenInstruction::NewTab(default_shell, layout, tab_name, client_id) => {
+                let tab_index = screen.get_new_tab_index();
+                screen.new_tab(tab_index, client_id)?;
+                screen
+                    .bus
+                    .senders
+                    .send_to_plugin(PluginInstruction::NewTab(
+                        default_shell,
+                        layout,
+                        tab_name,
+                        tab_index,
+                        client_id,
+                    ))?;
+            },
+            ScreenInstruction::ApplyLayout(
+                layout,
+                new_pane_pids,
+                new_plugin_ids,
+                tab_index,
+                client_id,
+            ) => {
+                screen.apply_layout(layout, new_pane_pids, new_plugin_ids, tab_index, client_id)?;
                 screen.unblock_input()?;
                 screen.render()?;
             },

zellij-server/src/tab/mod.rs

@@ -23,15 +23,14 @@ use crate::{
     panes::sixel::SixelImageStore,
     panes::{FloatingPanes, TiledPanes},
     panes::{LinkHandler, PaneId, PluginPane, TerminalPane},
+    plugins::PluginInstruction,
     pty::{ClientOrTabIndex, PtyInstruction, VteBytes},
     thread_bus::ThreadSenders,
-    wasm_vm::PluginInstruction,
     ClientId, ServerInstruction,
 };
 use serde::{Deserialize, Serialize};
 use std::cell::RefCell;
 use std::rc::Rc;
-use std::sync::mpsc::channel;
 use std::time::Instant;
 use std::{
     collections::{HashMap, HashSet},
@@ -41,7 +40,7 @@ use zellij_utils::{
     data::{Event, InputMode, ModeInfo, Palette, PaletteColor, Style},
     input::{
         command::TerminalAction,
-        layout::{PaneLayout, Run},
+        layout::{PaneLayout, Run, RunPluginLocation},
         parse_keys,
     },
     pane_size::{Offset, PaneGeom, Size, SizeInPixels, Viewport},
@@ -70,14 +69,19 @@ macro_rules! resize_pty {
     }};
 }
 
-type HoldForCommand = Option<RunCommand>;
-
 // FIXME: This should be replaced by `RESIZE_PERCENT` at some point
 pub const MIN_TERMINAL_HEIGHT: usize = 5;
 pub const MIN_TERMINAL_WIDTH: usize = 5;
 
 const MAX_PENDING_VTE_EVENTS: usize = 7000;
 
+type HoldForCommand = Option<RunCommand>;
+
+enum BufferedTabInstruction {
+    SetPaneSelectable(PaneId, bool),
+    HandlePtyBytes(u32, VteBytes),
+}
+
 pub(crate) struct Tab {
     pub index: usize,
     pub position: usize,
@@ -113,8 +117,11 @@ pub(crate) struct Tab {
     terminal_emulator_color_codes: Rc<RefCell<HashMap<usize, String>>>,
     pids_waiting_resize: HashSet<u32>, // u32 is the terminal_id
     cursor_positions_and_shape: HashMap<ClientId, (usize, usize, String)>, // (x_position,
-                                       // y_position,
-                                       // cursor_shape_csi)
+    // y_position,
+    // cursor_shape_csi)
+    is_pending: bool, // a pending tab is one that is still being loaded or otherwise waiting
+    pending_instructions: Vec<BufferedTabInstruction>, // instructions that came while the tab was
+                      // pending and need to be re-applied
 }
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize)]
@@ -489,13 +496,16 @@ impl Tab {
             terminal_emulator_color_codes,
             pids_waiting_resize: HashSet::new(),
             cursor_positions_and_shape: HashMap::new(),
+            is_pending: true, // will be switched to false once the layout is applied
+            pending_instructions: vec![],
         }
     }
 
     pub fn apply_layout(
         &mut self,
         layout: PaneLayout,
-        new_ids: Vec<(u32, HoldForCommand)>,
+        new_terminal_ids: Vec<(u32, HoldForCommand)>,
+        mut new_plugin_ids: HashMap<RunPluginLocation, Vec<u32>>,
         tab_index: usize,
         client_id: ClientId,
     ) -> Result<()> {
@@ -523,7 +533,7 @@ impl Tab {
         match layout.position_panes_in_space(&free_space) {
             Ok(positions_in_layout) => {
                 let positions_and_size = positions_in_layout.iter();
-                let mut new_ids = new_ids.iter();
+                let mut new_terminal_ids = new_terminal_ids.iter();
 
                 let mut focus_pane_id: Option<PaneId> = None;
                 let mut set_focus_pane_id = |layout: &PaneLayout, pane_id: PaneId| {
@@ -535,18 +545,16 @@ impl Tab {
                 for (layout, position_and_size) in positions_and_size {
                     // A plugin pane
                     if let Some(Run::Plugin(run)) = layout.run.clone() {
-                        let (pid_tx, pid_rx) = channel();
+                        // let (pid_tx, pid_rx) = channel();
                         let pane_title = run.location.to_string();
-                        self.senders
-                            .send_to_plugin(PluginInstruction::Load(
-                                pid_tx,
-                                run,
-                                tab_index,
-                                client_id,
-                                position_and_size.into(),
-                            ))
-                            .with_context(err_context)?;
-                        let pid = pid_rx.recv().with_context(err_context)?;
+                        let pid = new_plugin_ids
+                            .get_mut(&run.location)
+                            .unwrap()
+                            .pop()
+                            .unwrap(); // TODO:
+                                       // err_context
+                                       // and
+                                       // stuff
                         let mut new_plugin = PluginPane::new(
                             pid,
                             *position_and_size,
@@ -570,7 +578,7 @@ impl Tab {
                         set_focus_pane_id(layout, PaneId::Plugin(pid));
                     } else {
                         // there are still panes left to fill, use the pids we received in this method
-                        if let Some((pid, hold_for_command)) = new_ids.next() {
+                        if let Some((pid, hold_for_command)) = new_terminal_ids.next() {
                             let next_terminal_position = self.get_next_terminal_position();
                             let initial_title = match &layout.run {
                                 Some(Run::Command(run_command)) => Some(run_command.to_string()),
@@ -601,7 +609,7 @@ impl Tab {
                         }
                     }
                 }
-                for (unused_pid, _) in new_ids {
+                for (unused_pid, _) in new_terminal_ids {
                     // this is a bit of a hack and happens because we don't have any central location that
                     // can query the screen as to how many panes it needs to create a layout
                     // fixing this will require a bit of an architecture change
@@ -639,14 +647,17 @@ impl Tab {
                         },
                     }
                 }
+                self.is_pending = false;
+                self.apply_buffered_instructions()?;
                 Ok(())
             },
             Err(e) => {
-                for (unused_pid, _) in new_ids {
+                for (unused_pid, _) in new_terminal_ids {
                     self.senders
                         .send_to_pty(PtyInstruction::ClosePane(PaneId::Terminal(unused_pid)))
                         .with_context(err_context)?;
                 }
+                self.is_pending = false;
                 Err::<(), _>(anyError::msg(e))
                     .with_context(err_context)
                     .non_fatal(); // TODO: propagate this to the user
@@ -654,6 +665,21 @@ impl Tab {
             },
         }
     }
+    pub fn apply_buffered_instructions(&mut self) -> Result<()> {
+        let buffered_instructions: Vec<BufferedTabInstruction> =
+            self.pending_instructions.drain(..).collect();
+        for buffered_instruction in buffered_instructions {
+            match buffered_instruction {
+                BufferedTabInstruction::SetPaneSelectable(pane_id, selectable) => {
+                    self.set_pane_selectable(pane_id, selectable);
+                },
+                BufferedTabInstruction::HandlePtyBytes(terminal_id, bytes) => {
+                    self.handle_pty_bytes(terminal_id, bytes)?;
+                },
+            }
+        }
+        Ok(())
+    }
     pub fn update_input_modes(&mut self) -> Result<()> {
         // this updates all plugins with the client's input mode
         let mode_infos = self.mode_info.borrow();
@@ -1120,6 +1146,11 @@ impl Tab {
                 .any(|s_p| s_p.pid() == PaneId::Plugin(plugin_id))
     }
     pub fn handle_pty_bytes(&mut self, pid: u32, bytes: VteBytes) -> Result<()> {
+        if self.is_pending {
+            self.pending_instructions
+                .push(BufferedTabInstruction::HandlePtyBytes(pid, bytes));
+            return Ok(());
+        }
         let err_context = || format!("failed to handle pty bytes from fd {pid}");
         if let Some(terminal_output) = self
             .tiled_panes
@@ -1818,6 +1849,11 @@ impl Tab {
             .collect()
     }
     pub fn set_pane_selectable(&mut self, id: PaneId, selectable: bool) {
+        if self.is_pending {
+            self.pending_instructions
+                .push(BufferedTabInstruction::SetPaneSelectable(id, selectable));
+            return;
+        }
         if let Some(pane) = self.tiled_panes.get_pane_mut(id) {
             pane.set_selectable(selectable);
             if !selectable {
@@ -2807,6 +2843,10 @@ impl Tab {
         }
     }
 
+    pub fn is_pending(&self) -> bool {
+        self.is_pending
+    }
+
     fn show_floating_panes(&mut self) {
         // this function is to be preferred to directly invoking floating_panes.toggle_show_panes(true)
         self.floating_panes.toggle_show_panes(true);

zellij-server/src/tab/unit/tab_integration_tests.rs

@@ -224,8 +224,14 @@ fn create_new_tab(size: Size, default_mode: ModeInfo) -> Tab {
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 
@@ -274,8 +280,14 @@ fn create_new_tab_with_os_api(
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 
@@ -328,7 +340,7 @@ fn create_new_tab_with_layout(size: Size, default_mode: ModeInfo, layout: &str)
         .enumerate()
         .map(|(i, _)| (i as u32, None))
         .collect();
-    tab.apply_layout(tab_layout, pane_ids, index, client_id)
+    tab.apply_layout(tab_layout, pane_ids, HashMap::new(), index, client_id)
         .unwrap();
     tab
 }
@@ -379,8 +391,14 @@ fn create_new_tab_with_mock_pty_writer(
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 
@@ -432,8 +450,14 @@ fn create_new_tab_with_sixel_support(
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 

zellij-server/src/tab/unit/tab_tests.rs

@@ -138,8 +138,14 @@ fn create_new_tab(size: Size) -> Tab {
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 
@@ -185,8 +191,14 @@ fn create_new_tab_with_cell_size(
         terminal_emulator_colors,
         terminal_emulator_color_codes,
     );
-    tab.apply_layout(PaneLayout::default(), vec![(1, None)], index, client_id)
-        .unwrap();
+    tab.apply_layout(
+        PaneLayout::default(),
+        vec![(1, None)],
+        HashMap::new(),
+        index,
+        client_id,
+    )
+    .unwrap();
     tab
 }
 

zellij-server/src/thread_bus.rs

@@ -1,8 +1,8 @@
 //! Definitions and helpers for sending and receiving messages between threads.
 
 use crate::{
-    os_input_output::ServerOsApi, pty::PtyInstruction, pty_writer::PtyWriteInstruction,
-    screen::ScreenInstruction, wasm_vm::PluginInstruction, ServerInstruction,
+    os_input_output::ServerOsApi, plugins::PluginInstruction, pty::PtyInstruction,
+    pty_writer::PtyWriteInstruction, screen::ScreenInstruction, ServerInstruction,
 };
 use zellij_utils::errors::prelude::*;
 use zellij_utils::{channels, channels::SenderWithContext, errors::ErrorContext};

zellij-server/src/unit/screen_tests.rs

@@ -23,7 +23,7 @@ use std::env::set_var;
 use std::os::unix::io::RawFd;
 use std::sync::{Arc, Mutex};
 
-use crate::{pty::PtyInstruction, wasm_vm::PluginInstruction};
+use crate::{plugins::PluginInstruction, pty::PtyInstruction};
 use zellij_utils::ipc::PixelDimensions;
 
 use zellij_utils::{
@@ -221,7 +221,7 @@ fn create_new_screen(size: Size) -> Screen {
     let session_is_mirrored = true;
     let copy_options = CopyOptions::default();
 
-    Screen::new(
+    let screen = Screen::new(
         bus,
         &client_attributes,
         max_panes,
@@ -229,7 +229,8 @@ fn create_new_screen(size: Size) -> Screen {
         draw_pane_frames,
         session_is_mirrored,
         copy_options,
-    )
+    );
+    screen
 }
 
 struct MockScreen {
@@ -248,6 +249,7 @@ struct MockScreen {
     pub client_attributes: ClientAttributes,
     pub config_options: Options,
     pub session_metadata: SessionMetaData,
+    last_opened_tab_index: Option<usize>,
 }
 
 impl MockScreen {
@@ -280,27 +282,53 @@ impl MockScreen {
         let pane_layout = initial_layout.unwrap_or_default();
         let pane_count = pane_layout.extract_run_instructions().len();
         let mut pane_ids = vec![];
+        let plugin_ids = HashMap::new();
         for i in 0..pane_count {
             pane_ids.push((i as u32, None));
         }
+        let default_shell = None;
+        let tab_name = None;
+        let tab_index = self.last_opened_tab_index.map(|l| l + 1).unwrap_or(0);
         let _ = self.to_screen.send(ScreenInstruction::NewTab(
-            pane_layout,
-            pane_ids,
+            default_shell,
+            Some(pane_layout.clone()),
+            tab_name,
             self.main_client_id,
         ));
+        let _ = self.to_screen.send(ScreenInstruction::ApplyLayout(
+            pane_layout,
+            pane_ids,
+            plugin_ids,
+            tab_index,
+            self.main_client_id,
+        ));
+        self.last_opened_tab_index = Some(tab_index);
         screen_thread
     }
     pub fn new_tab(&mut self, tab_layout: PaneLayout) {
         let pane_count = tab_layout.extract_run_instructions().len();
         let mut pane_ids = vec![];
+        let plugin_ids = HashMap::new();
+        let default_shell = None;
+        let tab_name = None;
+        let tab_index = self.last_opened_tab_index.map(|l| l + 1).unwrap_or(0);
         for i in 0..pane_count {
             pane_ids.push((i as u32, None));
         }
         let _ = self.to_screen.send(ScreenInstruction::NewTab(
-            tab_layout,
-            pane_ids,
+            default_shell,
+            Some(tab_layout.clone()),
+            tab_name,
             self.main_client_id,
         ));
+        let _ = self.to_screen.send(ScreenInstruction::ApplyLayout(
+            tab_layout,
+            pane_ids,
+            plugin_ids,
+            0,
+            self.main_client_id,
+        ));
+        self.last_opened_tab_index = Some(tab_index);
     }
     pub fn teardown(&mut self, threads: Vec<std::thread::JoinHandle<()>>) {
         let _ = self.to_pty.send(PtyInstruction::Exit);
@@ -321,7 +349,7 @@ impl MockScreen {
             default_shell: self.session_metadata.default_shell.clone(),
             screen_thread: None,
             pty_thread: None,
-            wasm_thread: None,
+            plugin_thread: None,
             pty_writer_thread: None,
         }
     }
@@ -369,7 +397,7 @@ impl MockScreen {
             client_attributes: client_attributes.clone(),
             screen_thread: None,
             pty_thread: None,
-            wasm_thread: None,
+            plugin_thread: None,
             pty_writer_thread: None,
         };
 
@@ -392,6 +420,7 @@ impl MockScreen {
             client_attributes,
             config_options,
             session_metadata,
+            last_opened_tab_index: None,
         }
     }
 }
@@ -421,10 +450,19 @@ macro_rules! log_actions_in_thread {
     };
 }
 
-fn new_tab(screen: &mut Screen, pid: u32) {
+fn new_tab(screen: &mut Screen, pid: u32, tab_index: usize) {
     let client_id = 1;
+    let new_terminal_ids = vec![(pid, None)];
+    let new_plugin_ids = HashMap::new();
+    screen.new_tab(tab_index, client_id).expect("TEST");
     screen
-        .new_tab(PaneLayout::default(), vec![(pid, None)], client_id)
+        .apply_layout(
+            PaneLayout::default(),
+            new_terminal_ids,
+            new_plugin_ids,
+            tab_index,
+            client_id,
+        )
         .expect("TEST");
 }
 
@@ -436,8 +474,8 @@ fn open_new_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 1, 0);
+    new_tab(&mut screen, 2, 1);
 
     assert_eq!(screen.tabs.len(), 2, "Screen now has two tabs");
     assert_eq!(
@@ -455,8 +493,8 @@ pub fn switch_to_prev_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
     screen.switch_tab_prev(1).expect("TEST");
 
     assert_eq!(
@@ -474,8 +512,8 @@ pub fn switch_to_next_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
     screen.switch_tab_prev(1).expect("TEST");
     screen.switch_tab_next(1).expect("TEST");
 
@@ -494,8 +532,8 @@ pub fn close_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
     screen.close_tab(1).expect("TEST");
 
     assert_eq!(screen.tabs.len(), 1, "Only one tab left");
@@ -514,9 +552,9 @@ pub fn close_the_middle_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
-    new_tab(&mut screen, 3);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
+    new_tab(&mut screen, 3, 3);
     screen.switch_tab_prev(1).expect("TEST");
     screen.close_tab(1).expect("TEST");
 
@@ -536,9 +574,9 @@ fn move_focus_left_at_left_screen_edge_changes_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
-    new_tab(&mut screen, 3);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
+    new_tab(&mut screen, 3, 3);
     screen.switch_tab_prev(1).expect("TEST");
     screen.move_focus_left_or_previous_tab(1).expect("TEST");
 
@@ -557,9 +595,9 @@ fn move_focus_right_at_right_screen_edge_changes_tab() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
-    new_tab(&mut screen, 3);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
+    new_tab(&mut screen, 3, 3);
     screen.switch_tab_prev(1).expect("TEST");
     screen.move_focus_right_or_next_tab(1).expect("TEST");
 
@@ -578,8 +616,8 @@ pub fn toggle_to_previous_tab_simple() {
     };
     let mut screen = create_new_screen(position_and_size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 1, 1);
+    new_tab(&mut screen, 2, 2);
     screen.go_to_tab(1, 1).expect("TEST");
     screen.go_to_tab(2, 1).expect("TEST");
 
@@ -606,9 +644,9 @@ pub fn toggle_to_previous_tab_create_tabs_only() {
     };
     let mut screen = create_new_screen(position_and_size);
 
-    new_tab(&mut screen, 1);
-    new_tab(&mut screen, 2);
-    new_tab(&mut screen, 3);
+    new_tab(&mut screen, 1, 0);
+    new_tab(&mut screen, 2, 1);
+    new_tab(&mut screen, 3, 2);
 
     assert_eq!(
         screen.tab_history.get(&1).unwrap(),
@@ -656,10 +694,10 @@ pub fn toggle_to_previous_tab_delete() {
     };
     let mut screen = create_new_screen(position_and_size);
 
-    new_tab(&mut screen, 1); // 0
-    new_tab(&mut screen, 2); // 1
-    new_tab(&mut screen, 3); // 2
-    new_tab(&mut screen, 4); // 3
+    new_tab(&mut screen, 1, 0);
+    new_tab(&mut screen, 2, 1);
+    new_tab(&mut screen, 3, 2);
+    new_tab(&mut screen, 4, 3);
 
     assert_eq!(
         screen.tab_history.get(&1).unwrap(),
@@ -752,7 +790,7 @@ fn switch_to_tab_with_fullscreen() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
+    new_tab(&mut screen, 1, 1);
     {
         let active_tab = screen.get_active_tab_mut(1).unwrap();
         active_tab
@@ -760,7 +798,7 @@ fn switch_to_tab_with_fullscreen() {
             .unwrap();
         active_tab.toggle_active_pane_fullscreen(1);
     }
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 2, 2);
 
     screen.switch_tab_prev(1).expect("TEST");
 
@@ -867,7 +905,7 @@ fn attach_after_first_tab_closed() {
     };
     let mut screen = create_new_screen(size);
 
-    new_tab(&mut screen, 1);
+    new_tab(&mut screen, 1, 0);
     {
         let active_tab = screen.get_active_tab_mut(1).unwrap();
         active_tab
@@ -875,7 +913,7 @@ fn attach_after_first_tab_closed() {
             .unwrap();
         active_tab.toggle_active_pane_fullscreen(1);
     }
-    new_tab(&mut screen, 2);
+    new_tab(&mut screen, 2, 1);
 
     screen.close_tab_at_index(0).expect("TEST");
     screen.remove_client(1).expect("TEST");
@@ -2208,12 +2246,12 @@ pub fn send_cli_new_tab_action_default_params() {
     let mut mock_screen = MockScreen::new(size);
     let session_metadata = mock_screen.clone_session_metadata();
     let screen_thread = mock_screen.run(Some(initial_layout));
-    let received_pty_instructions = Arc::new(Mutex::new(vec![]));
-    let pty_receiver = mock_screen.pty_receiver.take().unwrap();
-    let pty_thread = log_actions_in_thread!(
-        received_pty_instructions,
-        PtyInstruction::Exit,
-        pty_receiver
+    let received_plugin_instructions = Arc::new(Mutex::new(vec![]));
+    let plugin_receiver = mock_screen.plugin_receiver.take().unwrap();
+    let plugin_thread = log_actions_in_thread!(
+        received_plugin_instructions,
+        PluginInstruction::Exit,
+        plugin_receiver
     );
     let new_tab_action = CliAction::NewTab {
         name: None,
@@ -2227,8 +2265,16 @@ pub fn send_cli_new_tab_action_default_params() {
         client_id,
     );
     std::thread::sleep(std::time::Duration::from_millis(100));
-    mock_screen.teardown(vec![pty_thread, screen_thread]);
-    assert_snapshot!(format!("{:?}", *received_pty_instructions.lock().unwrap()));
+    mock_screen.teardown(vec![plugin_thread, screen_thread]);
+    let received_plugin_instructions = received_plugin_instructions.lock().unwrap();
+    let new_tab_action =
+        received_plugin_instructions
+            .iter()
+            .find(|instruction| match instruction {
+                PluginInstruction::NewTab(..) => true,
+                _ => false,
+            });
+    assert_snapshot!(format!("{:#?}", new_tab_action));
 }
 
 #[test]
@@ -2241,12 +2287,12 @@ pub fn send_cli_new_tab_action_with_name_and_layout() {
     let mut mock_screen = MockScreen::new(size);
     let session_metadata = mock_screen.clone_session_metadata();
     let screen_thread = mock_screen.run(Some(initial_layout));
-    let received_pty_instructions = Arc::new(Mutex::new(vec![]));
-    let pty_receiver = mock_screen.pty_receiver.take().unwrap();
-    let pty_thread = log_actions_in_thread!(
-        received_pty_instructions,
-        PtyInstruction::Exit,
-        pty_receiver
+    let received_plugin_instructions = Arc::new(Mutex::new(vec![]));
+    let plugin_receiver = mock_screen.plugin_receiver.take().unwrap();
+    let plugin_thread = log_actions_in_thread!(
+        received_plugin_instructions,
+        PluginInstruction::Exit,
+        plugin_receiver
     );
     let new_tab_action = CliAction::NewTab {
         name: Some("my-awesome-tab-name".into()),
@@ -2263,13 +2309,14 @@ pub fn send_cli_new_tab_action_with_name_and_layout() {
         client_id,
     );
     std::thread::sleep(std::time::Duration::from_millis(100));
-    mock_screen.teardown(vec![pty_thread, screen_thread]);
-    let new_tab_instruction = received_pty_instructions
+    mock_screen.teardown(vec![plugin_thread, screen_thread]);
+    let new_tab_instruction = received_plugin_instructions
         .lock()
         .unwrap()
         .iter()
+        .rev()
         .find(|i| {
-            if let PtyInstruction::NewTab(..) = i {
+            if let PluginInstruction::NewTab(..) = i {
                 return true;
             } else {
                 return false;

zellij-server/src/unit/snapshots/zellij_server__screen__screen_tests__send_cli_new_tab_action_default_params.snap

@@ -1,6 +1,46 @@
 ---
 source: zellij-server/src/./unit/screen_tests.rs
-assertion_line: 1898
-expression: "format!(\"{:?}\", * received_pty_instructions.lock().unwrap())"
+assertion_line: 2272
+expression: "format!(\"{:#?}\", new_tab_action)"
 ---
-[NewTab(None, None, None, 10), UpdateActivePane(Some(Terminal(0)), 1), UpdateActivePane(Some(Terminal(0)), 1), Exit]
+Some(
+    NewTab(
+        None,
+        Some(
+            PaneLayout {
+                children_split_direction: Vertical,
+                name: None,
+                children: [
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+            },
+        ),
+        None,
+        0,
+        1,
+    ),
+)

zellij-server/src/unit/snapshots/zellij_server__screen__screen_tests__send_cli_new_tab_action_with_name_and_layout.snap

@@ -1,6 +1,6 @@
 ---
 source: zellij-server/src/./unit/screen_tests.rs
-assertion_line: 2287
+assertion_line: 2322
 expression: "format!(\"{:#?}\", new_tab_instruction)"
 ---
 NewTab(
@@ -63,5 +63,6 @@ NewTab(
     Some(
         "my-awesome-tab-name",
     ),
+    1,
     10,
 )

zellij-server/src/unit/snapshots/zellij_server__screen__screen_tests__send_cli_rename_tab.snap

@@ -1,6 +1,6 @@
 ---
 source: zellij-server/src/./unit/screen_tests.rs
-assertion_line: 2528
+assertion_line: 2506
 expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
 ---
 [
@@ -18,6 +18,45 @@ expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
         ),
         InputReceived,
     ),
+    NewTab(
+        None,
+        Some(
+            PaneLayout {
+                children_split_direction: Horizontal,
+                name: None,
+                children: [
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+            },
+        ),
+        None,
+        0,
+        1,
+    ),
     Update(
         None,
         Some(
@@ -190,6 +229,45 @@ expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
             ],
         ),
     ),
+    NewTab(
+        None,
+        Some(
+            PaneLayout {
+                children_split_direction: Vertical,
+                name: None,
+                children: [
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+            },
+        ),
+        None,
+        1,
+        1,
+    ),
     Update(
         None,
         Some(

zellij-server/src/unit/snapshots/zellij_server__screen__screen_tests__send_cli_undo_rename_tab.snap

@@ -1,6 +1,6 @@
 ---
 source: zellij-server/src/./unit/screen_tests.rs
-assertion_line: 2571
+assertion_line: 2549
 expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
 ---
 [
@@ -18,6 +18,45 @@ expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
         ),
         InputReceived,
     ),
+    NewTab(
+        None,
+        Some(
+            PaneLayout {
+                children_split_direction: Horizontal,
+                name: None,
+                children: [
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+            },
+        ),
+        None,
+        0,
+        1,
+    ),
     Update(
         None,
         Some(
@@ -190,6 +229,45 @@ expression: "format!(\"{:#?}\", * received_plugin_instructions.lock().unwrap())"
             ],
         ),
     ),
+    NewTab(
+        None,
+        Some(
+            PaneLayout {
+                children_split_direction: Vertical,
+                name: None,
+                children: [
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                    PaneLayout {
+                        children_split_direction: Horizontal,
+                        name: None,
+                        children: [],
+                        split_size: None,
+                        run: None,
+                        borderless: false,
+                        focus: None,
+                        external_children_index: None,
+                    },
+                ],
+                split_size: None,
+                run: None,
+                borderless: false,
+                focus: None,
+                external_children_index: None,
+            },
+        ),
+        None,
+        1,
+        1,
+    ),
     Update(
         None,
         Some(

zellij-server/src/wasm_vm.rs

@@ -1,785 +0,0 @@
-use highway::{HighwayHash, PortableHash};
-use log::{debug, info, warn};
-use semver::Version;
-use serde::{de::DeserializeOwned, Serialize};
-use std::{
-    collections::{HashMap, HashSet},
-    fmt, fs,
-    path::{Path, PathBuf},
-    process,
-    str::FromStr,
-    sync::{mpsc::Sender, Arc, Mutex},
-    thread,
-    time::{Duration, Instant},
-};
-use url::Url;
-use wasmer::{
-    imports, ChainableNamedResolver, Function, ImportObject, Instance, Module, Store, Value,
-    WasmerEnv,
-};
-use wasmer_wasi::{Pipe, WasiEnv, WasiState};
-
-use crate::{
-    logging_pipe::LoggingPipe,
-    panes::PaneId,
-    pty::{ClientOrTabIndex, PtyInstruction},
-    screen::ScreenInstruction,
-    thread_bus::{Bus, ThreadSenders},
-    ClientId,
-};
-
-use zellij_utils::{
-    consts::{DEBUG_MODE, VERSION, ZELLIJ_CACHE_DIR, ZELLIJ_TMP_DIR},
-    data::{Event, EventType, PluginIds},
-    errors::{prelude::*, ContextType, PluginContext},
-    input::{
-        command::TerminalAction,
-        layout::RunPlugin,
-        plugins::{PluginConfig, PluginType, PluginsConfig},
-    },
-    pane_size::Size,
-    serde,
-};
-
-/// Custom error for plugin version mismatch.
-///
-/// This is thrown when, during starting a plugin, it is detected that the plugin version doesn't
-/// match the zellij version. This is treated as a fatal error and leads to instantaneous
-/// termination.
-#[derive(Debug)]
-pub struct VersionMismatchError {
-    zellij_version: String,
-    plugin_version: String,
-    plugin_path: PathBuf,
-    // true for builtin plugins
-    builtin: bool,
-}
-
-impl std::error::Error for VersionMismatchError {}
-
-impl VersionMismatchError {
-    pub fn new(
-        zellij_version: &str,
-        plugin_version: &str,
-        plugin_path: &PathBuf,
-        builtin: bool,
-    ) -> Self {
-        VersionMismatchError {
-            zellij_version: zellij_version.to_owned(),
-            plugin_version: plugin_version.to_owned(),
-            plugin_path: plugin_path.to_owned(),
-            builtin,
-        }
-    }
-}
-
-impl fmt::Display for VersionMismatchError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        let first_line = if self.builtin {
-            "It seems your version of zellij was built with outdated core plugins."
-        } else {
-            "If you're seeing this error a plugin version doesn't match the current
-zellij version."
-        };
-
-        write!(
-            f,
-            "{}
-Detected versions:
-
-- Plugin version: {}
-- Zellij version: {}
-- Offending plugin: {}
-
-If you're a user:
-    Please contact the distributor of your zellij version and report this error
-    to them.
-
-If you're a developer:
-    Please run zellij with updated plugins. The easiest way to achieve this
-    is to build zellij with `cargo make install`. Also refer to the docs:
-    https://github.com/zellij-org/zellij/blob/main/CONTRIBUTING.md#building
-",
-            first_line,
-            self.plugin_version.trim_end(),
-            self.zellij_version.trim_end(),
-            self.plugin_path.display()
-        )
-    }
-}
-
-#[derive(Clone, Debug)]
-pub enum PluginInstruction {
-    Load(Sender<u32>, RunPlugin, usize, ClientId, Size), // tx_pid, plugin metadata, tab_index, client_ids
-    Update(Option<u32>, Option<ClientId>, Event), // Focused plugin / broadcast, client_id, event data
-    Unload(u32),                                  // plugin_id
-    Resize(u32, usize, usize),                    // plugin_id, columns, rows
-    AddClient(ClientId),
-    RemoveClient(ClientId),
-    Exit,
-}
-
-impl From<&PluginInstruction> for PluginContext {
-    fn from(plugin_instruction: &PluginInstruction) -> Self {
-        match *plugin_instruction {
-            PluginInstruction::Load(..) => PluginContext::Load,
-            PluginInstruction::Update(..) => PluginContext::Update,
-            PluginInstruction::Unload(..) => PluginContext::Unload,
-            PluginInstruction::Resize(..) => PluginContext::Resize,
-            PluginInstruction::Exit => PluginContext::Exit,
-            PluginInstruction::AddClient(_) => PluginContext::AddClient,
-            PluginInstruction::RemoveClient(_) => PluginContext::RemoveClient,
-        }
-    }
-}
-
-#[derive(WasmerEnv, Clone)]
-pub(crate) struct PluginEnv {
-    pub plugin_id: u32,
-    pub plugin: PluginConfig,
-    pub senders: ThreadSenders,
-    pub wasi_env: WasiEnv,
-    pub subscriptions: Arc<Mutex<HashSet<EventType>>>,
-    pub tab_index: usize,
-    pub client_id: ClientId,
-    #[allow(dead_code)]
-    plugin_own_data_dir: PathBuf,
-}
-
-// Thread main --------------------------------------------------------------------------------------------------------
-pub(crate) fn wasm_thread_main(
-    bus: Bus<PluginInstruction>,
-    store: Store,
-    data_dir: PathBuf,
-    plugins: PluginsConfig,
-) -> Result<()> {
-    info!("Wasm main thread starts");
-
-    let mut plugin_id = 0;
-    let mut headless_plugins = HashMap::new();
-    let mut plugin_map: HashMap<(u32, ClientId), (Instance, PluginEnv, (usize, usize))> =
-        HashMap::new(); // u32 => pid, (usize, usize) => rows/columns TODO: clean this up into a struct or something
-    let mut connected_clients: Vec<ClientId> = vec![];
-    let plugin_dir = data_dir.join("plugins/");
-    let plugin_global_data_dir = plugin_dir.join("data");
-    // Caches the "wasm bytes" of all plugins that have been loaded since zellij was started.
-    // Greatly decreases loading times of all plugins and avoids accesses to the hard-drive during
-    // "regular" operation.
-    let mut plugin_cache: HashMap<PathBuf, Module> = HashMap::new();
-
-    loop {
-        let (event, mut err_ctx) = bus.recv().expect("failed to receive event on channel");
-        err_ctx.add_call(ContextType::Plugin((&event).into()));
-        match event {
-            PluginInstruction::Load(pid_tx, run, tab_index, client_id, size) => {
-                let err_context = || format!("failed to load plugin for client {client_id}");
-
-                let plugin = plugins
-                    .get(&run)
-                    .with_context(|| format!("failed to resolve plugin {run:?}"))
-                    .with_context(err_context)
-                    .fatal();
-
-                let (instance, plugin_env) = start_plugin(
-                    plugin_id,
-                    client_id,
-                    &plugin,
-                    tab_index,
-                    &bus,
-                    &store,
-                    &plugin_dir,
-                    &mut plugin_cache,
-                )
-                .with_context(err_context)?;
-
-                let mut main_user_instance = instance.clone();
-                let main_user_env = plugin_env.clone();
-                load_plugin(&mut main_user_instance).with_context(err_context)?;
-
-                plugin_map.insert(
-                    (plugin_id, client_id),
-                    (main_user_instance, main_user_env, (size.rows, size.cols)),
-                );
-
-                // clone plugins for the rest of the client ids if they exist
-                for client_id in connected_clients.iter() {
-                    let mut new_plugin_env = plugin_env.clone();
-                    new_plugin_env.client_id = *client_id;
-                    let module = instance.module().clone();
-                    let wasi = new_plugin_env
-                        .wasi_env
-                        .import_object(&module)
-                        .with_context(err_context)?;
-                    let zellij = zellij_exports(&store, &new_plugin_env);
-                    let mut instance = Instance::new(&module, &zellij.chain_back(wasi))
-                        .with_context(err_context)?;
-                    load_plugin(&mut instance).with_context(err_context)?;
-                    plugin_map.insert(
-                        (plugin_id, *client_id),
-                        (instance, new_plugin_env, (size.rows, size.cols)),
-                    );
-                }
-                pid_tx.send(plugin_id).with_context(err_context)?;
-                plugin_id += 1;
-            },
-            PluginInstruction::Update(pid, cid, event) => {
-                let err_context = || {
-                    if *DEBUG_MODE.get().unwrap_or(&true) {
-                        format!("failed to update plugin state with event: {event:#?}")
-                    } else {
-                        "failed to update plugin state".to_string()
-                    }
-                };
-
-                for (&(plugin_id, client_id), (instance, plugin_env, (rows, columns))) in
-                    &plugin_map
-                {
-                    let subs = plugin_env
-                        .subscriptions
-                        .lock()
-                        .to_anyhow()
-                        .with_context(err_context)?;
-                    // FIXME: This is very janky... Maybe I should write my own macro for Event -> EventType?
-                    let event_type =
-                        EventType::from_str(&event.to_string()).with_context(err_context)?;
-                    if subs.contains(&event_type)
-                        && ((pid.is_none() && cid.is_none())
-                            || (pid.is_none() && cid == Some(client_id))
-                            || (cid.is_none() && pid == Some(plugin_id))
-                            || (cid == Some(client_id) && pid == Some(plugin_id)))
-                    {
-                        let update = instance
-                            .exports
-                            .get_function("update")
-                            .with_context(err_context)?;
-                        wasi_write_object(&plugin_env.wasi_env, &event);
-                        let update_return =
-                            update.call(&[]).or_else::<anyError, _>(|e| match e
-                                .downcast::<serde_json::Error>()
-                            {
-                                Ok(_) => panic!(
-                                    "{}",
-                                    anyError::new(VersionMismatchError::new(
-                                        VERSION,
-                                        "Unavailable",
-                                        &plugin_env.plugin.path,
-                                        plugin_env.plugin.is_builtin(),
-                                    ))
-                                ),
-                                Err(e) => Err(e).with_context(err_context),
-                            })?;
-                        let should_render = match update_return.get(0) {
-                            Some(Value::I32(n)) => *n == 1,
-                            _ => false,
-                        };
-
-                        if *rows > 0 && *columns > 0 && should_render {
-                            let render = instance
-                                .exports
-                                .get_function("render")
-                                .with_context(err_context)?;
-                            render
-                                .call(&[Value::I32(*rows as i32), Value::I32(*columns as i32)])
-                                .with_context(err_context)?;
-                            let rendered_bytes = wasi_read_string(&plugin_env.wasi_env);
-                            drop(bus.senders.send_to_screen(ScreenInstruction::PluginBytes(
-                                plugin_id,
-                                client_id,
-                                rendered_bytes.as_bytes().to_vec(),
-                            )));
-                        }
-                    }
-                }
-            },
-            PluginInstruction::Unload(pid) => {
-                info!("Bye from plugin {}", &pid);
-                // TODO: remove plugin's own data directory
-                let ids_in_plugin_map: Vec<(u32, ClientId)> = plugin_map.keys().copied().collect();
-                for (plugin_id, client_id) in ids_in_plugin_map {
-                    if pid == plugin_id {
-                        drop(plugin_map.remove(&(plugin_id, client_id)));
-                    }
-                }
-            },
-            PluginInstruction::Resize(pid, new_columns, new_rows) => {
-                let err_context = || format!("failed to resize plugin {pid}");
-                for (
-                    (plugin_id, client_id),
-                    (instance, plugin_env, (current_rows, current_columns)),
-                ) in plugin_map.iter_mut()
-                {
-                    if *plugin_id == pid {
-                        *current_rows = new_rows;
-                        *current_columns = new_columns;
-
-                        // TODO: consolidate with above render function
-                        let render = instance
-                            .exports
-                            .get_function("render")
-                            .with_context(err_context)?;
-
-                        render
-                            .call(&[
-                                Value::I32(*current_rows as i32),
-                                Value::I32(*current_columns as i32),
-                            ])
-                            .with_context(err_context)?;
-                        let rendered_bytes = wasi_read_string(&plugin_env.wasi_env);
-                        drop(bus.senders.send_to_screen(ScreenInstruction::PluginBytes(
-                            *plugin_id,
-                            *client_id,
-                            rendered_bytes.as_bytes().to_vec(),
-                        )));
-                    }
-                }
-            },
-            PluginInstruction::AddClient(client_id) => {
-                let err_context = || format!("failed to add plugins for client {client_id}");
-
-                connected_clients.push(client_id);
-
-                let mut seen = HashSet::new();
-                let mut new_plugins = HashMap::new();
-                for (&(plugin_id, _), (instance, plugin_env, (rows, columns))) in &plugin_map {
-                    if seen.contains(&plugin_id) {
-                        continue;
-                    }
-                    seen.insert(plugin_id);
-                    let mut new_plugin_env = plugin_env.clone();
-
-                    new_plugin_env.client_id = client_id;
-                    new_plugins.insert(
-                        plugin_id,
-                        (instance.module().clone(), new_plugin_env, (*rows, *columns)),
-                    );
-                }
-                for (plugin_id, (module, mut new_plugin_env, (rows, columns))) in
-                    new_plugins.drain()
-                {
-                    let wasi = new_plugin_env
-                        .wasi_env
-                        .import_object(&module)
-                        .with_context(err_context)?;
-                    let zellij = zellij_exports(&store, &new_plugin_env);
-                    let mut instance = Instance::new(&module, &zellij.chain_back(wasi))
-                        .with_context(err_context)?;
-                    load_plugin(&mut instance).with_context(err_context)?;
-                    plugin_map.insert(
-                        (plugin_id, client_id),
-                        (instance, new_plugin_env, (rows, columns)),
-                    );
-                }
-
-                // load headless plugins
-                for plugin in plugins.iter() {
-                    if let PluginType::Headless = plugin.run {
-                        let (instance, plugin_env) = start_plugin(
-                            plugin_id,
-                            client_id,
-                            plugin,
-                            0,
-                            &bus,
-                            &store,
-                            &plugin_dir,
-                            &mut plugin_cache,
-                        )
-                        .with_context(err_context)?;
-                        headless_plugins.insert(plugin_id, (instance, plugin_env));
-                        plugin_id += 1;
-                    }
-                }
-            },
-            PluginInstruction::RemoveClient(client_id) => {
-                connected_clients.retain(|c| c != &client_id);
-            },
-            PluginInstruction::Exit => break,
-        }
-    }
-    info!("wasm main thread exits");
-
-    fs::remove_dir_all(&plugin_global_data_dir)
-        .or_else(|err| {
-            if err.kind() == std::io::ErrorKind::NotFound {
-                // I don't care...
-                Ok(())
-            } else {
-                Err(err)
-            }
-        })
-        .context("failed to cleanup plugin data directory")
-}
-
-#[allow(clippy::too_many_arguments)]
-fn start_plugin(
-    plugin_id: u32,
-    client_id: ClientId,
-    plugin: &PluginConfig,
-    tab_index: usize,
-    bus: &Bus<PluginInstruction>,
-    store: &Store,
-    plugin_dir: &Path,
-    plugin_cache: &mut HashMap<PathBuf, Module>,
-) -> Result<(Instance, PluginEnv)> {
-    let err_context = || format!("failed to start plugin {plugin:#?} for client {client_id}");
-
-    let plugin_own_data_dir = ZELLIJ_CACHE_DIR.join(Url::from(&plugin.location).to_string());
-    let cache_hit = plugin_cache.contains_key(&plugin.path);
-
-    // We remove the entry here and repopulate it at the very bottom, if everything went well.
-    // We must do that because a `get` will only give us a borrow of the Module. This suffices for
-    // the purpose of setting everything up, but we cannot return a &Module from the "None" match
-    // arm, because we create the Module from scratch there. Any reference passed outside would
-    // outlive the Module we create there. Hence, we remove the plugin here and reinsert it
-    // below...
-    let module = match plugin_cache.remove(&plugin.path) {
-        Some(module) => {
-            log::debug!(
-                "Loaded plugin '{}' from plugin cache",
-                plugin.path.display()
-            );
-            module
-        },
-        None => {
-            // Populate plugin module cache for this plugin!
-            // Is it in the cache folder already?
-            if plugin._allow_exec_host_cmd {
-                info!(
-                    "Plugin({:?}) is able to run any host command, this may lead to some security issues!",
-                    plugin.path
-                );
-            }
-
-            // The plugins blob as stored on the filesystem
-            let wasm_bytes = plugin
-                .resolve_wasm_bytes(plugin_dir)
-                .with_context(err_context)
-                .fatal();
-
-            fs::create_dir_all(&plugin_own_data_dir)
-                .with_context(|| format!("failed to create datadir in {plugin_own_data_dir:?}"))
-                .with_context(err_context)
-                .non_fatal();
-
-            // ensure tmp dir exists, in case it somehow was deleted (e.g systemd-tmpfiles)
-            fs::create_dir_all(ZELLIJ_TMP_DIR.as_path())
-                .with_context(|| {
-                    format!("failed to create tmpdir at {:?}", &ZELLIJ_TMP_DIR.as_path())
-                })
-                .with_context(err_context)
-                .non_fatal();
-
-            let hash: String = PortableHash::default()
-                .hash256(&wasm_bytes)
-                .iter()
-                .map(ToString::to_string)
-                .collect();
-            let cached_path = ZELLIJ_CACHE_DIR.join(&hash);
-
-            unsafe {
-                match Module::deserialize_from_file(store, &cached_path) {
-                    Ok(m) => {
-                        log::debug!(
-                            "Loaded plugin '{}' from cache folder at '{}'",
-                            plugin.path.display(),
-                            ZELLIJ_CACHE_DIR.display(),
-                        );
-                        m
-                    },
-                    Err(e) => {
-                        let inner_context = || format!("failed to recover from {e:?}");
-
-                        let m = Module::new(store, &wasm_bytes)
-                            .with_context(inner_context)
-                            .with_context(err_context)?;
-                        fs::create_dir_all(ZELLIJ_CACHE_DIR.to_owned())
-                            .with_context(inner_context)
-                            .with_context(err_context)?;
-                        m.serialize_to_file(&cached_path)
-                            .with_context(inner_context)
-                            .with_context(err_context)?;
-                        m
-                    },
-                }
-            }
-        },
-    };
-
-    let mut wasi_env = WasiState::new("Zellij")
-        .env("CLICOLOR_FORCE", "1")
-        .map_dir("/host", ".")
-        .and_then(|wasi| wasi.map_dir("/data", &plugin_own_data_dir))
-        .and_then(|wasi| wasi.map_dir("/tmp", ZELLIJ_TMP_DIR.as_path()))
-        .and_then(|wasi| {
-            wasi.stdin(Box::new(Pipe::new()))
-                .stdout(Box::new(Pipe::new()))
-                .stderr(Box::new(LoggingPipe::new(
-                    &plugin.location.to_string(),
-                    plugin_id,
-                )))
-                .finalize()
-        })
-        .with_context(err_context)?;
-    let wasi = wasi_env.import_object(&module).with_context(err_context)?;
-
-    let mut mut_plugin = plugin.clone();
-    mut_plugin.set_tab_index(tab_index);
-    let plugin_env = PluginEnv {
-        plugin_id,
-        client_id,
-        plugin: mut_plugin,
-        senders: bus.senders.clone(),
-        wasi_env,
-        subscriptions: Arc::new(Mutex::new(HashSet::new())),
-        plugin_own_data_dir,
-        tab_index,
-    };
-
-    let zellij = zellij_exports(store, &plugin_env);
-    let instance = Instance::new(&module, &zellij.chain_back(wasi)).with_context(err_context)?;
-
-    if !cache_hit {
-        // Check plugin version
-        assert_plugin_version(&instance, &plugin_env).with_context(err_context)?;
-    }
-
-    // Only do an insert when everything went well!
-    let cloned_plugin = plugin.clone();
-    plugin_cache.insert(cloned_plugin.path, module);
-
-    Ok((instance, plugin_env))
-}
-
-// Returns `Ok` if the plugin version matches the zellij version.
-// Returns an `Err` otherwise.
-fn assert_plugin_version(instance: &Instance, plugin_env: &PluginEnv) -> Result<()> {
-    let err_context = || {
-        format!(
-            "failed to determine plugin version for plugin {}",
-            plugin_env.plugin.path.display()
-        )
-    };
-
-    let plugin_version_func = match instance.exports.get_function("plugin_version") {
-        Ok(val) => val,
-        Err(_) => {
-            return Err(anyError::new(VersionMismatchError::new(
-                VERSION,
-                "Unavailable",
-                &plugin_env.plugin.path,
-                plugin_env.plugin.is_builtin(),
-            )))
-        },
-    };
-    plugin_version_func.call(&[]).with_context(err_context)?;
-    let plugin_version_str = wasi_read_string(&plugin_env.wasi_env);
-    let plugin_version = Version::parse(&plugin_version_str)
-        .context("failed to parse plugin version")
-        .with_context(err_context)?;
-    let zellij_version = Version::parse(VERSION)
-        .context("failed to parse zellij version")
-        .with_context(err_context)?;
-    if plugin_version != zellij_version {
-        return Err(anyError::new(VersionMismatchError::new(
-            VERSION,
-            &plugin_version_str,
-            &plugin_env.plugin.path,
-            plugin_env.plugin.is_builtin(),
-        )));
-    }
-
-    Ok(())
-}
-
-fn load_plugin(instance: &mut Instance) -> Result<()> {
-    let err_context = || format!("failed to load plugin from instance {instance:#?}");
-
-    let load_function = instance
-        .exports
-        .get_function("_start")
-        .with_context(err_context)?;
-    // This eventually calls the `.load()` method
-    load_function.call(&[]).with_context(err_context)?;
-    Ok(())
-}
-
-// Plugin API ---------------------------------------------------------------------------------------------------------
-
-pub(crate) fn zellij_exports(store: &Store, plugin_env: &PluginEnv) -> ImportObject {
-    macro_rules! zellij_export {
-        ($($host_function:ident),+ $(,)?) => {
-            imports! {
-                "zellij" => {
-                    $(stringify!($host_function) =>
-                        Function::new_native_with_env(store, plugin_env.clone(), $host_function),)+
-                }
-            }
-        }
-    }
-
-    zellij_export! {
-        host_subscribe,
-        host_unsubscribe,
-        host_set_selectable,
-        host_get_plugin_ids,
-        host_get_zellij_version,
-        host_open_file,
-        host_switch_tab_to,
-        host_set_timeout,
-        host_exec_cmd,
-        host_report_panic,
-    }
-}
-
-fn host_subscribe(plugin_env: &PluginEnv) {
-    let mut subscriptions = plugin_env.subscriptions.lock().unwrap();
-    let new: HashSet<EventType> = wasi_read_object(&plugin_env.wasi_env);
-    subscriptions.extend(new);
-}
-
-fn host_unsubscribe(plugin_env: &PluginEnv) {
-    let mut subscriptions = plugin_env.subscriptions.lock().unwrap();
-    let old: HashSet<EventType> = wasi_read_object(&plugin_env.wasi_env);
-    subscriptions.retain(|k| !old.contains(k));
-}
-
-fn host_set_selectable(plugin_env: &PluginEnv, selectable: i32) {
-    match plugin_env.plugin.run {
-        PluginType::Pane(Some(tab_index)) => {
-            let selectable = selectable != 0;
-            plugin_env
-                .senders
-                .send_to_screen(ScreenInstruction::SetSelectable(
-                    PaneId::Plugin(plugin_env.plugin_id),
-                    selectable,
-                    tab_index,
-                ))
-                .unwrap()
-        },
-        _ => {
-            debug!(
-                "{} - Calling method 'host_set_selectable' does nothing for headless plugins",
-                plugin_env.plugin.location
-            )
-        },
-    }
-}
-
-fn host_get_plugin_ids(plugin_env: &PluginEnv) {
-    let ids = PluginIds {
-        plugin_id: plugin_env.plugin_id,
-        zellij_pid: process::id(),
-    };
-    wasi_write_object(&plugin_env.wasi_env, &ids);
-}
-
-fn host_get_zellij_version(plugin_env: &PluginEnv) {
-    wasi_write_object(&plugin_env.wasi_env, VERSION);
-}
-
-fn host_open_file(plugin_env: &PluginEnv) {
-    let path: PathBuf = wasi_read_object(&plugin_env.wasi_env);
-    plugin_env
-        .senders
-        .send_to_pty(PtyInstruction::SpawnTerminal(
-            Some(TerminalAction::OpenFile(path, None)),
-            None,
-            None,
-            ClientOrTabIndex::TabIndex(plugin_env.tab_index),
-        ))
-        .unwrap();
-}
-
-fn host_switch_tab_to(plugin_env: &PluginEnv, tab_idx: u32) {
-    plugin_env
-        .senders
-        .send_to_screen(ScreenInstruction::GoToTab(
-            tab_idx,
-            Some(plugin_env.client_id),
-        ))
-        .unwrap();
-}
-
-fn host_set_timeout(plugin_env: &PluginEnv, secs: f64) {
-    // There is a fancy, high-performance way to do this with zero additional threads:
-    // If the plugin thread keeps a BinaryHeap of timer structs, it can manage multiple and easily `.peek()` at the
-    // next time to trigger in O(1) time. Once the wake-up time is known, the `wasm` thread can use `recv_timeout()`
-    // to wait for an event with the timeout set to be the time of the next wake up. If events come in in the meantime,
-    // they are handled, but if the timeout triggers, we replace the event from `recv()` with an
-    // `Update(pid, TimerEvent)` and pop the timer from the Heap (or reschedule it). No additional threads for as many
-    // timers as we'd like.
-    //
-    // But that's a lot of code, and this is a few lines:
-    let send_plugin_instructions = plugin_env.senders.to_plugin.clone();
-    let update_target = Some(plugin_env.plugin_id);
-    let client_id = plugin_env.client_id;
-    thread::spawn(move || {
-        let start_time = Instant::now();
-        thread::sleep(Duration::from_secs_f64(secs));
-        // FIXME: The way that elapsed time is being calculated here is not exact; it doesn't take into account the
-        // time it takes an event to actually reach the plugin after it's sent to the `wasm` thread.
-        let elapsed_time = Instant::now().duration_since(start_time).as_secs_f64();
-
-        send_plugin_instructions
-            .unwrap()
-            .send(PluginInstruction::Update(
-                update_target,
-                Some(client_id),
-                Event::Timer(elapsed_time),
-            ))
-            .unwrap();
-    });
-}
-
-fn host_exec_cmd(plugin_env: &PluginEnv) {
-    let mut cmdline: Vec<String> = wasi_read_object(&plugin_env.wasi_env);
-    let command = cmdline.remove(0);
-
-    // Bail out if we're forbidden to run command
-    if !plugin_env.plugin._allow_exec_host_cmd {
-        warn!("This plugin isn't allow to run command in host side, skip running this command: '{cmd} {args}'.",
-        	cmd = command, args = cmdline.join(" "));
-        return;
-    }
-
-    // Here, we don't wait the command to finish
-    process::Command::new(command)
-        .args(cmdline)
-        .spawn()
-        .unwrap();
-}
-
-// Custom panic handler for plugins.
-//
-// This is called when a panic occurs in a plugin. Since most panics will likely originate in the
-// code trying to deserialize an `Event` upon a plugin state update, we read some panic message,
-// formatted as string from the plugin.
-fn host_report_panic(plugin_env: &PluginEnv) {
-    let msg = wasi_read_string(&plugin_env.wasi_env);
-    panic!("{}", msg);
-}
-
-// Helper Functions ---------------------------------------------------------------------------------------------------
-
-pub fn wasi_read_string(wasi_env: &WasiEnv) -> String {
-    let mut state = wasi_env.state();
-    let wasi_file = state.fs.stdout_mut().unwrap().as_mut().unwrap();
-    let mut buf = String::new();
-    wasi_file.read_to_string(&mut buf).unwrap();
-    // https://stackoverflow.com/questions/66450942/in-rust-is-there-a-way-to-make-literal-newlines-in-r-using-windows-c
-    buf.replace("\n", "\n\r")
-}
-
-pub fn wasi_write_string(wasi_env: &WasiEnv, buf: &str) {
-    let mut state = wasi_env.state();
-    let wasi_file = state.fs.stdin_mut().unwrap().as_mut().unwrap();
-    writeln!(wasi_file, "{}\r", buf).unwrap();
-}
-
-pub fn wasi_write_object(wasi_env: &WasiEnv, object: &(impl Serialize + ?Sized)) {
-    wasi_write_string(wasi_env, &serde_json::to_string(&object).unwrap());
-}
-
-pub fn wasi_read_object<T: DeserializeOwned>(wasi_env: &WasiEnv) -> T {
-    let json = wasi_read_string(wasi_env);
-    serde_json::from_str(&json).unwrap()
-}

zellij-utils/src/errors.rs

@@ -285,6 +285,7 @@ pub enum ScreenContext {
     UpdatePaneName,
     UndoRenamePane,
     NewTab,
+    ApplyLayout,
     SwitchTabNext,
     SwitchTabPrev,
     CloseTab,
@@ -350,6 +351,7 @@ pub enum PluginContext {
     Exit,
     AddClient,
     RemoveClient,
+    NewTab,
 }
 
 /// Stack call representations corresponding to the different types of [`ClientInstruction`]s.