release: 0.4.0

[davideast]

Bumps version from 0.3.0 to 0.4.0. All changes since 0.3.0:

Bug Fixes

• Missing design files fail gracefully instead of throwing a stack trace. Reading a non-existent or unreadable file now outputs a clean error message and structured JSON with exit code 2. (fix(cli): single structured error and correct exit code on input failure #123, fix: graceful ENOENT error when DESIGN.md is missing (#132) #145, @rmyndharis, @Emp1500) Fixes ENOENT: no such file or directory error when DESIGN.md is missing #132.
• Successful exports always return exit code 0. Export command exit codes are now decoupled from source document linter warnings or errors, ensuring valid serialized builds pass pipeline gates. (fix(export): exit 0 on a successful export regardless of source lint findings #126, fix(export): set exit code 0 on a successful export #152, @rmyndharis, @arpitjain099)
• Tailwind CSS exports end with exactly one trailing newline. Serializing to css-tailwind no longer appends an extra empty line that caused strict repository formatting checks to fail. (fix(export): remove extra trailing newline in css-tailwind output #151, fix(cli): single trailing newline on css-tailwind export #140, Fix css-tailwind extra trailing newline #144, @sudarshandev-llm, @drmikecrypto, @Jalendar10) Fixes css-tailwind export emits an extra trailing newline #139.
• Reading from an interactive terminal prints a usage hint. When running a command with - as the input path from a TTY, the CLI prints Reading from stdin... Press Ctrl+D when done to prevent silent freezing. (fix(stdin): show TTY hint when reading from interactive terminal #146, @Emp1500)
• Gradian angle units in colors parse correctly. Angles like 100grad now correctly take precedence over radian matching, producing accurate color computations and contrast metrics. (fix(color): correct grad hue parsing and reject non-percentage color-mix weights #120, @rmyndharis)
• CSS color-mix() requires explicit percentage weight values. Bare numbers are now rejected instead of producing inaccurate color blends. (fix(color): correct grad hue parsing and reject non-percentage color-mix weights #120, @rmyndharis)
• Line terminators in font family names are escaped in Tailwind v4 exports. (fix(export): escape line terminators in Tailwind v4 CSS string values #122, @rmyndharis)
• Specification documentation resolves reliably from bundled CLI installations. The CLI command npx @google/design.md spec no longer throws errors when executed from npm installations. (fix: bundle spec.md next to the CLI entry so the spec command works after build #118, Fix/spec command path #157, @rmyndharis, @SyedaQurratAI)
• Primitive types render correctly directly from specification configuration. (fix: render primitive types from spec config #131, @juliosuas)
• Bounded token validation performance on adversarial inputs. Cap dimension string parsing lengths, limit recursion depth in nested colors, and optimize string distance checks to prevent CPU spikes or call stack errors on malformed documents. (perf: bound token-validation cost on adversarial input #121, @rmyndharis)

Features

• Optional omitted frontmatter key suppresses linter warnings. Design authors can explicitly list skipped categories (like spacing or rounded) as bare strings or structured objects with reasons, silencing expected-missing linter warnings. (feat: add omitted frontmatter key to suppress expected-missing lint warnings #155, feat: add omitted frontmatter key to suppress expected-missing lint warnings #113, feat(linter): add \omitted\ key to suppress missing-section warnings #147, @zachshallbetter, @mvanhorn, @sudarshandev-llm) Fixes Feature: omitted key to declare intentional absence and suppress expected-missing warnings #78.
• CSS custom properties export format. Serializes design system tokens directly into standard CSS variables within a :root selector using --format css-vars, with optional naming prefix support via --prefix. (feat: add CSS custom properties export format (--format css-vars) #109, @mvanhorn)
• Typography sub-property linting. The linter now reports warnings for unrecognized or misspelled property fields inside typography token mappings. (feat(lint): flag unrecognized typography sub-properties #125, @rmyndharis)
• Token name collision detection. The linter detects and reports naming collisions occurring between flattened dot-notation keys and nested YAML groups. (feat(linter): detect token name collisions for flat vs grouped keys #150, @Arshgill01)
• Data-driven type definitions in specification. Specification documentation dynamically generated from primitive configuration schemas. (feat: data-driven Color and Dimension type definitions (fixes #97) #117, @Emp1500) Fixes Color type definition is not driven by spec-config.yaml #97.

Docs

• Updated README to match runtime linter JSON output fields (infos vs info) and align the active rules count to eleven. (docs: correct lint/diff output examples and rule count in README #119, @rmyndharis)
• Declared supported Node runtime compatibility requirement ("engines": { "node": ">=18.0.0" }) in package metadata. (chore: declare supported Node engine range (>=18) #124, @rmyndharis)

Contributors

Thank you to the contributors who made this release possible:

• @rmyndharis (fix: bundle spec.md next to the CLI entry so the spec command works after build #118, docs: correct lint/diff output examples and rule count in README #119, fix(color): correct grad hue parsing and reject non-percentage color-mix weights #120, perf: bound token-validation cost on adversarial input #121, fix(export): escape line terminators in Tailwind v4 CSS string values #122, fix(cli): single structured error and correct exit code on input failure #123, chore: declare supported Node engine range (>=18) #124, feat(lint): flag unrecognized typography sub-properties #125, fix(export): exit 0 on a successful export regardless of source lint findings #126)
• @Emp1500 (feat: data-driven Color and Dimension type definitions (fixes #97) #117, fix: graceful ENOENT error when DESIGN.md is missing (#132) #145, fix(stdin): show TTY hint when reading from interactive terminal #146)
• @mvanhorn (feat: add CSS custom properties export format (--format css-vars) #109, feat: add omitted frontmatter key to suppress expected-missing lint warnings #113, feat: add omitted frontmatter key to suppress expected-missing lint warnings #155)
• @sudarshandev-llm (feat(linter): add \omitted\ key to suppress missing-section warnings #147, fix(export): remove extra trailing newline in css-tailwind output #151, feat: add omitted frontmatter key to suppress expected-missing lint warnings #155)
• @zachshallbetter (feat: add omitted frontmatter key to suppress expected-missing lint warnings #155)
• @juliosuas (fix: render primitive types from spec config #131)
• @Arshgill01 (feat(linter): detect token name collisions for flat vs grouped keys #150)
• @arpitjain099 (fix(export): set exit code 0 on a successful export #152)
• @SyedaQurratAI (Fix/spec command path #157)
• @drmikecrypto (fix(cli): single trailing newline on css-tailwind export #140)
• @Jalendar10 (Fix css-tailwind extra trailing newline #144)