Seq Language for VS Code

Syntax, diagnostics, and build inspection for the Seq programming language,ordered workflows written as plain-language requests and compiled by seqc into native executables.

model("https://huggingface.co/Qwen/Qwen2.5-Coder-1.5B-Instruct")
backend.C()
name = "top3Company"

step step1():
    ask("create a database file company.txt with 5 sample stock transactions")

step step2():
    ask("for each transaction created give me the total revenue of the company")

Features

Editing

• Syntax highlighting for .seq files, with escapes and tabs marked as invalid
• Outline, breadcrumbs, and folding per step
• Completion for the header declarations, step, and ask()
• Hover documentation for every keyword, and the byte count of a request against the 4096-byte limit
• Snippets: workflow, header, step, ask
• Format Document: indentation normalized to 0 or 4 spaces, trailing whitespace removed
• Rename a step (F2)

Diagnostics

• seqc check runs when a .seq file is opened or saved; every error appears in Problems with its code (linked to the language reference) and its hint
• Quick fixes for the usual slips: ask "x" → ask("x"), model = "…" → model("…"), backend = "c" → backend.C(), tabs and wrong indentation, missing header declarations, duplicate step names, step parameters

Running

• Seq: Run Workflow, Build Only, Rebuild, Check, Doctor, Pull Model, Clean,each runs seqc in a task terminal
• Run button in the editor title, and CodeLens above the workflow: Run · Build only · Check · Rebuild · build status
• The status bar follows the build stages (plan, generate, compile, test, run)
• A failed build offers the next step: compare repair attempts, run seqc doctor, pull the model, retry with --force
• seqc tasks (run, build, check) for tasks.json, and a $seqc problem matcher

Build inspection

• CodeLens above each step: the result of the last run, a jump to its generated C function (seq_step_N), and what the plan says it reads and writes
• The Seq Build view in the Explorer: the accepted build (generated C with one entry per step function, assembly, tests, build.json), the published outputs, and every run record with its plan, attempts, logs, and manifests
• Compare a repair attempt with the previous one in the diff editor
• JSON schemas for build.json, plan.json, and run-manifest.json

The extension never writes under output/. What it shows is what seqc left on disk.

Requirements

• seqc 0.1 on the PATH (or set seq.seqcPath). Without it, editing features still work; diagnostics and the run commands need it.
• seqc builds and runs workflows on Linux x86_64 only. On Windows, either open the project in a Remote – WSL window (recommended), or set seq.useWsl to run the seqc of your default WSL distribution from a Windows window.
• Running seqc is disabled in untrusted workspaces.

Settings

Commands

seqc builds <project>/src/main.seq; a .seq file elsewhere can be checked but not built.

Development

npm install
npm run build          # bundle to dist/extension.js
npm test               # unit tests (vitest) and grammar snapshots
npm run test:integration   # runs inside a downloaded VS Code
SEQ_E2E=1 npm run test:integration   # also checks a file with a real seqc

Press F5 in VS Code to launch the extension against tests/fixtures/project, a recorded project with an accepted build and two run records.

License

MIT. Seq itself is at github.com/tomjnet/seq-lang.