Anvil

Anvil is a Linux-first terminal editor. The project targets a reusable Rust kernel, a per-session Go policy gateway, and a capability-scoped plugin host. The official standard edition is one composition; third-party distributions can compose the kernel with their own UI and trusted Rust code. Runtime plugins remain untrusted and sandboxed.

Status: 0.4.5 released; 0.4.x feature line active. Release model: 0.3.0 → 0.4.0 maintenance closed. Development uses Rust from rust-toolchain.toml and Go 1.26.10 or newer; CI installs the exact Go version from the root go.mod. The ratatui editor now includes insert mode (i/a/A/o/O), multi-cursor selection (s/Alt-s/C), :w/:wa/:wq/:w file/:q!, an unsaved-change guard, undo/redo, x/dd/yy/p, w/b/e word motions with dw/db/de/yw/yb/ye, literal :s/:%s substitution, / search with n/N, multi-buffer switching, vertical splits with independent pane cursors, horizontal scrolling, and dirty-only redraws, insert-mode Tab indentation, a workspace file tree, and a fuzzy file finder. Rust, TOML, Go, Bash, Python, YAML, JSON/JSONC, Markdown, Makefile, and Dockerfile use Tree-sitter highlighting on a debounced background thread, capped at 256 KiB so large files keep plain-text latency. Trusted language servers (rust-analyzer, gopls, pyright/pylsp, typescript-language-server/vtsls, clangd, jdtls, lua-language-server, vscode-json-language-server, yaml-language-server, bash-language-server) run without the plugin sandbox; diagnostics, completion (Ctrl+Space), definition (gd), hover (K), rename (Space r), code actions/quick fixes (Space a), formatting (Space F), document symbols (Space s), signature help, and workspace symbols (Space S) use canonicalized LSP UTF-16 positions. Rename, code-action, and formatting edits go through a shared WorkspaceEdit engine; unopened files become background buffers, and :wa saves every modified buffer without silently writing files during an edit. Supported files start their language server automatically; each (tool, language_id) keeps its own worker while the session is open. Language servers are not bundled; install them on PATH.

• TypeScript support requires a project-local compiler: run npm install -D typescript (or pnpm add -D typescript) in the project.
• C/C++ support works best with a compilation database: bear -- make, or configure CMake with -DCMAKE_EXPORT_COMPILE_COMMANDS=ON. Without it, clangd may report unresolved includes.

The plugin-host path has an empty sandboxed host with token-FD delivery, close_range, no_new_privs, Landlock read/no-exec rules, native-ABI seccomp with AF_UNIX-only sockets, cgroup v2 limits with OOM classification, framed sys.ping/sys.exec dispatch, and a TUI debug PluginSession (:plugin-start/:plugin-exec/:plugin-stop/:plugin-oom). Local plugin manifests are discovered from child directories of ANVIL_PLUGIN_DIR. onLanguage and onWorkspaceContains events start matching sandboxed hosts with no grants. onStartup requires explicit opt-in via ANVIL_PLUGIN_ALLOW_STARTUP=1; workspace activation is disabled with ANVIL_PLUGIN_DISABLE_WORKSPACE_ACTIVATION=1. onCommand dispatch and the supervisor lifecycle are still pending. This is not a VM or public plugin API.

Phase 0 still consists of the anvil-api contracts, anvil-core PieceTable, anvil-editor snapshots, anvil-ipc framing/JSON-RPC/Unix transport, and the Go gateway with openat2, Landlock/seccomp exec sandboxing, SSRF-constrained fetch, and a synchronous Rust gateway client. The TUI discovers the gateway beside the binary or via ANVIL_GATEWAY.

Usage

anvil [OPTIONS] [FILE]

  -w, --workspace <DIR>  Workspace directory; --workspace=DIR is also accepted
  -h, --help             Show help and exit
  -V, --version          Show the version and exit
  --                     Treat the next argument as FILE

FILE must be inside the selected workspace. Use -- before a file name that starts with a dash. Launching without FILE shows the start dashboard; the first key dismisses it.

Documents

• Installing Anvil
• Project charter
• Known issues
• High-frequency command architecture plan
• 0.3.0 → 0.4.0: Polish & Specification
• 0.3.0 → 0.4.0 / Phase 0.7 plan
• 0.4.x feature plan
• Keymap configuration
• Plugin-host isolation ADR
• Threat model
• Architecture
• Current and future architecture maps
• Deployment model
• Ratatui TUI Elm loop plan
• Performance baseline
• Go gateway benchmarks
• File operation benchmarks
• Text model benchmark
• Editor benchmarks
• Line index stress
• TUI edit-loop latency
• Phase 0.5 plan
• Phase 0.6 plan
• Upstream dependencies
• JSON-RPC and token contract
• Kernel/distribution boundary
• Selection-first interaction
• Text-model snapshot gate
• Cursor and snapshot ownership
• Workspace file I/O protocol
• Workspace tree watching
• Terminal keyboard enhancement
• Architecture decision records
• Governance
• Maintainers
• Release process
• Support
• Roadmap
• Security policy
• Contributing
• Code of conduct
• Changelog

Current decisions

• Plugins are untrusted by default and run in a separate plugin-host process, never in the editor process.

• The Rust v1 stack uses ratatui + crossterm directly, with no Tokio or Ferriso runtime dependency. Ferriso is reference material.

• Lua plugins use mlua with Luau; TS uses rquickjs (QuickJS-NG), not V8.

• The Go gateway is a per-session policy gateway, not the plugin sandbox. One gateway process owns one session socket; closing the server removes the socket.

• sys.exec routes through anvil-exec-runner. The Phase 0.6 gateway uses a one-shot 32-byte bootstrap token: the gateway holds only its SHA-256 verifier, the raw token appears only in session.hello, and a second handshake is rejected. SO_PEERCRED UID plus the token are both required. -allow-exec is currently per gateway instance; per-session permission negotiation remains open.

• The public API starts small and is defined from Rust types plus generated JSON Schema and TypeScript/Lua stubs. Smithy is deferred until the API justifies its code-generation cost.

• The text model is PieceTable, exposed as anvil-core::TextDocument; Rope and Gap Buffer remain benchmark-only. See ADR-0009.

• Syntax highlighting is derived state, not stored in PieceTable. Parsing runs on a background worker after a 50 ms debounce; stale spans remain visible until the replacement arrives. Files over 256 KiB are intentionally plain text.

• The empty plugin host is a real process/sandbox boundary, but not yet a plugin runtime. cgroup limits require a delegated cgroup2 root; without one the host fails closed rather than pretending limits are active.

• The native editor/API interaction model is selection-first. The current TUI exposes that core through a Vim-like keymap implemented in Rust. Normal and operator-pending bindings can be remapped through keymap.toml; Lua/TS keymap plugins are not implemented yet.

• Full untrusted-plugin support targets Linux 5.13+ (Landlock). Linux 5.6-5.12 may run the editor with trusted plugins only.

License

Licensed under either of Apache-2.0 or MIT, at your option. See LICENSE-APACHE and LICENSE-MIT.