zed-noir

March 18, 2026 ยท View on GitHub

Noir support for Zed.

This extension now has a working local development loop with:

  • tree-sitter-based syntax highlighting
  • outline support for core Noir declarations
  • nargo lsp startup through the extension runtime

Workspace Layout

  • languages/noir/config.toml
  • languages/noir/highlights.scm
  • languages/noir/outline.scm
  • extension.toml
  • src/lib.rs

The extension currently points at the local tree-sitter-noir repository during development.

Local Development Loop

Extension validation:

cd zed-noir
cargo check

Grammar validation:

cd ../tree-sitter-noir
tree-sitter generate
tree-sitter test
tree-sitter parse examples/simple.nr
tree-sitter parse examples/edge_cases.nr

Runtime validation:

zeditor --foreground /path/to/file.nr

When iterating on the dev extension in Zed, use the Noir extension's Rebuild action after changes. In this workspace, that has been the most reliable way to force Zed to rebuild and reload both the Rust extension runtime and the grammar integration.

Rebuild Workflow

There are two separate WASM artifacts:

  1. The extension runtime:
cd zed-noir
cargo build --release --target wasm32-wasip2
cp target/wasm32-wasip2/release/zed_noir.wasm extension.wasm
  1. The tree-sitter grammar:
cd ../tree-sitter-noir
tree-sitter build --wasm
cp tree-sitter-noir.wasm ../zed-noir/grammars/noir.wasm

Important:

  • extension.wasm must come from wasm32-wasip2
  • wasm32-wasip1 produces the wrong format for the current Zed extension runtime
  • rebuilding only one of the two WASM files can leave the extension in a confusing half-working state
  • after local changes, the Zed dev extension Rebuild action is usually still required before editor behavior updates in a running session
  • if the grammar source URL changes during development, a stale generated checkout in zed-noir/grammars/noir can block rebuilds until it is removed and recreated

Troubleshooting

No syntax highlighting

Likely area:

  • grammar build or grammar reload

Check:

  • confirm grammars/noir.wasm exists
  • use the Noir dev extension Rebuild action

If Zed reports that grammars/noir is not a git clone of the configured repository:

  • remove the generated zed-noir/grammars/noir checkout
  • rebuild the dev extension so Zed recreates it from the current grammar source

Syntax highlighting works, but hover and diagnostics do not

Likely area:

  • extension runtime or LSP startup

Check:

  • confirm extension.wasm was built from wasm32-wasip2
  • run zeditor --foreground path/to/file.nr
  • look for a foreground log line like:
[lsp] starting language server process ... args: ["lsp"]

If that line never appears, the Noir buffer probably did not attach a running language server.

Highlighting or hover behavior looks stale after local changes

Likely area:

  • dev extension reload state

Check:

  • use the Noir dev extension Rebuild action, even if you already restarted Zed
  • then re-open a Noir file and re-check behavior

In this workspace, Rebuild has been more reliable than restart alone.

You are not sure whether the problem is grammar, runtime, or LSP

Use this split:

  • no syntax highlighting: suspect grammar build/reload
  • syntax highlighting but no hover/diagnostics: suspect extension runtime or nargo lsp
  • plain-text hover with minimal formatting: LSP is running, but hover payload quality is limited by nargo lsp

Current Limitations

  • Hover quality is currently limited by the nargo lsp payload. The extension can start the language server, but hover content is still mostly plain text.
  • Foreground logs are more reliable than ~/.local/share/zed/logs/Zed.log in this workspace. Disk-backed log updates have been inconsistent.
  • Highlighting is coherent for common Noir code, but not yet polished to the level of flagship language extensions.
  • Reload behavior is still somewhat manual: a plain editor restart is not always enough, and using the dev extension Rebuild action remains part of the normal workflow.

Real Project Fixture

The primary local Noir project used for validation is:

  • ../firma/src/main.nr

It is useful for checking:

  • trailing-comma parameter parsing
  • imported function calls
  • assert highlighting
  • LSP attachment inside a real Noir project