Problem Matcher Builder

Paste your CLI's error output. Tag the parts. Get a working tasks.json problem matcher back.

When a tool doesn't ship its own VS Code problem matcher — most linters, build scripts, and custom CLIs — you have to hand-write a regex-based JSON block by trial and error. The usual ritual: copy an error line, paste it into an external regex tester, hand-craft the pattern, then remember that JSON needs every backslash escaped a second time. Get it wrong and VS Code's only feedback is "the description can't be converted into a problem matcher" — no line number, no hint.

This extension replaces that ritual.

How it works

1. Open the builder — run Problem Matcher Builder: Open Builder from the Command Palette.
2. Paste sample output — a few real error lines from your tool, exactly as they appear in the terminal.
3. Write a pattern — a regular expression, matched live against every line. Each capture group is painted onto your output in its own color.
4. Tag the groups — click a highlight (or use the dropdown) to say which group is the file, the line, the message, and so on.
5. Copy or insert — the generated problemMatcher JSON is correctly escaped and ready to paste into your tasks.json.

The status tag at the top reads DRAFT until you've tagged a message group, then flips to RESOLVED once it's producing valid output.

Why the escaping is handled for you

The regex is held as a normal string and serialized with a standard JSON serializer, so every backslash is escaped exactly once — by construction, not by remembering. \d+ in the builder becomes \\d+ in the JSON, which is what VS Code needs. No more silent breakage from a swallowed backslash.

What's supported today

Single-line problem patterns — the shape the overwhelming majority of tools produce (file(line,col): severity: message and its many variants). Multi-line and watch/background matchers are planned.

From CodeFront Studio

Small, sharp developer tools that fix one specific annoying problem. codefrontstudio.com