Spice

Spice Language Extension for Zed

Syntax highlighting and language server support for SPICE circuit netlists in the Zed editor.

Supported files

Extension	Description
`.cir`, `.sp`, `.spi`	Circuit netlists
`.lib`	Model/subcircuit libraries
`.mod`, `.mdl`	Model files

Features

Syntax highlighting via tree-sitter-spice: component cards, .subckt/.ends, .model, other dot commands, numbers with engineering suffixes (4.7k, 100n), behavioral expressions ({V(a)-V(b)}), and comments (*, ;, $, //)
Line comment toggling with *
Bracket matching for () and {}
Language server (spice-lsp, downloaded automatically):
- Completion for dot-command directives (with docs) and .subckt/.model names (current file + includes)
- Hover: built-in dot-command documentation, subcircuit port lists, model types
- Go to definition and find references for .subckt/.model, across .include/.lib files
- Document symbols / outline
- Document formatting (whitespace normalization)
- Diagnostics: unbalanced blocks, undefined subcircuit/model references, port-count mismatches, duplicate instance names
Run the current netlist through a simulator via a "run" gutter button on .tran/.ac/.dc/.op lines (see Running a simulation)

Running a simulation

languages/spice/runnables.scm tags simulation-analysis directives (.tran, .ac, .dc, .op, .noise, .tf) as runnable, and languages/spice/tasks.json bundles a matching task that invokes ngspice -b $ZED_FILE.

I haven't been able to verify end-to-end whether Zed actually picks up an extension-bundled tasks.json automatically — this is a real gap even in Zed's own documentation (their tasks doc lists "by language extension" as one of four ways tasks are defined, but doesn't document the exact mechanism, and a GitHub discussion about adding default run tasks for built-in languages like C/C++ suggests this doesn't happen automatically even for languages Zed ships itself). If the gutter run button doesn't appear or doesn't do anything for you, add the same task to your project's .zed/tasks.json — that mechanism is stable and well-documented:

[
  {
    "label": "Run SPICE ($ZED_FILENAME)",
    "command": "ngspice",
    "args": ["-b", "$ZED_FILE"],
    "tags": ["spice-run"],
    "use_new_terminal": false,
    "reveal": "always"
  }
]

The default command assumes ngspice is on your PATH. If you use LTspice, HSPICE, or another simulator, change command/args to match (e.g. LTspice on macOS: "/Applications/LTspice.app/Contents/MacOS/LTspice" with ["-b", "$ZED_FILE"]).

Not supported

A few other file types share the "SPICE" name or ecosystem but are out of scope for this extension:

LTspice schematics (.asc) and symbols (.asy)
LTspice simulation output (.raw) - binary waveform data
NASA/NAIF SPICE toolkit kernels (.bsp, .tpc, .tls) - spacecraft ephemeris data from an entirely unrelated "SPICE" (NASA's, not Berkeley's)

Spice netlist example

* Example RC low-pass filter
.param VDD=5

.subckt lpf in out
R1 in mid 4.7k
C1 mid 0 100n
.ends lpf

X1 vin vout lpf
V1 vin 0 PULSE(0 {VDD} 0 1n 1n 1m 2m)

.tran 0 10m
.end

Installation

From Zed extension registry

Search for Spice in zed: extensions.

Local development

# In Zed, open command palette and run:
# zed: install dev extension
# Point it at the spice-lang directory