Crate Mountain 

Mountain: Native Backend for Code Editor Land

Mountain replaces Electron with Rust and Tauri. It manages windows, file systems, processes, and extensions at native speed. Where Electron takes milliseconds, Mountain responds in microseconds.

What Mountain Does

• Hosts the editor UI via Tauri webview (no Chromium process overhead)
• Runs VS Code extensions by managing the Cocoon sidecar over gRPC
• Handles file I/O through native async Rust (tokio), not Node.js fs
• Manages terminals via native PTY (portable-pty), not shell wrappers
• Stores secrets in the OS keychain (keyring crate), not plaintext

Architecture

Mountain uses a declarative effect system defined in Common. Business logic is expressed as ActionEffects executed by the ApplicationRunTime. All state lives in a single thread-safe ApplicationState managed by Tauri.

Wind/Sky (UI) ──Tauri commands──> Mountain ──gRPC──> Cocoon (extensions)
                                     │
                                     ├── Environment providers (file, process, terminal)
                                     ├── ApplicationRunTime (effect executor)
                                     └── ApplicationState (shared state)

Module Layout

Core Infrastructure

• ApplicationState: Centralized, thread-safe state for the entire app
• Environment: Capability providers (file system, processes, extensions)
• RunTime: Effect execution engine that runs ActionEffect pipelines

Communication

• IPC: Inter-process communication primitives
• Air: Client for the background daemon (updates, crypto signing)
• Vine: gRPC server/client for Cocoon extension host communication
• RPC: Remote procedure call service implementations

Services

• ProcessManagement: Sidecar process lifecycle (launch, monitor, restart)
• FileSystem: Native TreeView provider for the File Explorer
• ExtensionManagement: Extension discovery, scanning, and activation

Commands

• Command: Native command handlers (file, edit, view, terminal)
• Track: Central command dispatcher routing UI requests to providers
• Workspace: .code-workspace file parsing and multi-root support

Related Crates

Crate	Role
Common	Abstract traits and DTOs that Mountain implements
Echo	Work-stealing task scheduler used by Mountain’s runtime
Air	Background daemon that Mountain communicates with

Getting Started

Mountain builds as part of the Land monorepo:

cargo build -p Mountain

Full setup: https://github.com/CodeEditorLand/Land

Modules

Air

Air (Air Integration Module)

ApplicationState

Centralised, thread-safe state for the Mountain application. Held inside MountainEnvironment and accessed via Arc<...> clones from every provider. Sub-modules:

Binary

Binary Module

Cache

Mountain caching primitives.

Command

Command Module

Environment

Environment Module

Error

Centralized error handling system Local error stack. Currently dead code - every Mountain consumer uses CommonLibrary::Error::CommonError instead. Files remain in place to preserve the original taxonomy; remove or migrate when the strategy is settled.

ExtensionManagement

Extension lifecycle: scan bundled + user-installed extension trees, parse their package.json manifests, install VSIX archives. Mountain owns the discovery surface; activation runs in Cocoon over gRPC.

FileSystem

Native file-explorer surface for the workspace sidebar. Mountain owns the tree-view provider; URIs flow through CommonLibrary::FileSystem traits.

IPC

IPC Module

LandFixTier

LandFixTier

ProcessManagement

Process Management Module

RPC

Mountain RPC services. The active surface is CocoonService - the tonic server impl that Cocoon dials into. The other modules here (EchoAction, Commands, Workspace, Configuration, plus the Windows/Terminals/Debug/SCM/Processes/Telemetry cfg-feature shells) are scaffolding for the multi-extension-host roadmap; most carry zero external callers today.

RunTime

RunTime Module

Track

Track Module

Vine

Vine gRPC Module

Workspace

Workspace lifecycle: .code-workspace parsing, multi-root folder resolution, workspace-scoped configuration. Implements CommonLibrary::Workspace::WorkspaceProvider over ApplicationState.

Macros

TraceStep

Logs a checkpoint message at TRACE level (for “every step” tracing).

dev_log

Log a tagged dev message. Only prints if the tag is enabled via Trace.

impl_provider

Macro to generate Requires<T> trait implementations for MountainEnvironment.

otel_span

Convenience macro: emit an OTLP span for an IPC handler. Usage: otel_span!("file:readFile", StartNano, &[("path", &SomePath)]);

Functions

main

Main entry point for both mobile and desktop builds.