<div align="center">
# SpecSync
[](https://github.com/marketplace/actions/spec-sync)
[](https://github.com/CorvidLabs/spec-sync/actions/workflows/ci.yml)
[](https://crates.io/crates/specsync)
[](LICENSE)
**Bidirectional spec-to-code validation.** Written in Rust. Single binary. 9 languages.
[Quick Start](#quick-start) • [Spec Format](#spec-format) • [CLI](#cli-reference) • [GitHub Action](#github-action) • [Config](#configuration) • [Docs Site](https://corvidlabs.github.io/spec-sync)
</div>
---
## What It Does
SpecSync validates markdown module specs (`*.spec.md`) against your source code in both directions:
| Code exports something not in the spec | Warning | Undocumented export |
| Spec documents something missing from code | **Error** | Stale/phantom entry |
| Source file in spec was deleted | **Error** | Missing file |
| DB table in spec missing from schema | **Error** | Phantom table |
| Required markdown section missing | **Error** | Incomplete spec |
## Supported Languages
Auto-detected from file extensions. Same spec format for all.
| **TypeScript/JS** | `export function/class/type/const/enum`, re-exports | `.test.ts`, `.spec.ts`, `.d.ts` |
| **Rust** | `pub fn/struct/enum/trait/type/const/static/mod` | `#[cfg(test)]` modules |
| **Go** | Uppercase `func/type/var/const`, methods | `_test.go` |
| **Python** | `__all__`, or top-level `def/class` (no `_` prefix) | `test_*.py`, `*_test.py` |
| **Swift** | `public/open` func/class/struct/enum/protocol/actor | `*Tests.swift` |
| **Kotlin** | Top-level declarations (excludes private/internal) | `*Test.kt`, `*Spec.kt` |
| **Java** | `public` class/interface/enum/record/methods | `*Test.java`, `*Tests.java` |
| **C#** | `public` class/struct/interface/enum/record/delegate | `*Test.cs`, `*Tests.cs` |
| **Dart** | Top-level (no `_` prefix), class/mixin/enum/typedef | `*_test.dart` |
---
## Install
### GitHub Action (recommended)
```yaml
- uses: CorvidLabs/spec-sync@v1
with:
strict: 'true'
require-coverage: '100'
```
### Crates.io
```bash
cargo install specsync
```
### Pre-built binaries
Download from [GitHub Releases](https://github.com/CorvidLabs/spec-sync/releases):
```bash
# macOS (Apple Silicon)
# macOS (Intel)
curl -sL https://github.com/CorvidLabs/spec-sync/releases/latest/download/specsync-macos-x86_64.tar.gz | tar xz
sudo mv specsync-macos-x86_64 /usr/local/bin/specsync
# Linux (x86_64)
curl -sL https://github.com/CorvidLabs/spec-sync/releases/latest/download/specsync-linux-x86_64.tar.gz | tar xz
sudo mv specsync-linux-x86_64 /usr/local/bin/specsync
# Linux (aarch64)
```
**Windows:** download `specsync-windows-x86_64.exe.zip` from the [releases page](https://github.com/CorvidLabs/spec-sync/releases).
### From source
```bash
cargo install --git https://github.com/CorvidLabs/spec-sync
```
---
## Quick Start
```bash
specsync init # Create specsync.json config
specsync check # Validate specs against code
specsync coverage # Show file/module coverage
specsync generate # Scaffold specs for unspecced modules
specsync generate --provider auto # AI-powered specs (auto-detect provider)
specsync generate --provider anthropic # Use Anthropic API directly (no CLI needed)
specsync score # Quality-score your spec files (0–100)
specsync mcp # Start MCP server for AI agent integration
specsync watch # Re-validate on every file change
```
---
## Spec Format
Specs are markdown files (`*.spec.md`) with YAML frontmatter in your specs directory.
### Frontmatter
```yaml
---
module: auth # Module name (required)
version: 3 # Spec version (required)
- src/auth/service.ts
- src/auth/middleware.ts
db_tables: # Validated against schema dir (optional)
- users
- sessions
depends_on: # Other spec paths, validated for existence (optional)
- specs/database/database.spec.md
---
```
### Required Sections
Every spec must include these `##` sections (configurable in `specsync.json`):
Purpose, Public API, Invariants, Behavioral Examples, Error Cases, Dependencies, Change Log
### Public API Tables
SpecSync extracts the first backtick-quoted name per row and cross-references it against code exports:
```markdown
## Public API
| `authenticate` | `(token: string)` | `User \| null` | Validates bearer token |
| `refreshSession` | `(sessionId: string)` | `Session` | Extends session TTL |
```
<details>
<summary>Full spec example</summary>
```markdown
---
module: auth
version: 3
status: stable
files:
- src/auth/service.ts
- src/auth/middleware.ts
db_tables:
- users
- sessions
depends_on:
- specs/database/database.spec.md
---
# Auth
## Purpose
Handles authentication and session management. Validates bearer tokens,
manages session lifecycle, provides middleware for route protection.
## Public API
### Exported Functions
| `authenticate` | `(token: string)` | `User \| null` | Validates a token |
| `refreshSession` | `(sessionId: string)` | `Session` | Extends session TTL |
### Exported Types
| `User` | Authenticated user object |
| `Session` | Active session record |
## Invariants
1. Sessions expire after 24 hours
2. Failed auth attempts rate-limited to 5/minute
3. Tokens validated cryptographically, never by string comparison
## Behavioral Examples
### Scenario: Valid token
- **Given** a valid JWT token
- **When** `authenticate()` is called
- **Then** returns the corresponding User object
### Scenario: Expired token
- **Given** an expired JWT token
- **When** `authenticate()` is called
- **Then** returns null and logs a warning
## Error Cases
| Expired token | Returns null, logs warning |
| Malformed token | Returns null |
| DB unavailable | Throws `ServiceUnavailableError` |
## Dependencies
| database | `query()` for user lookups |
| crypto | `verifyJwt()` for token validation |
## Change Log
| 2026-03-18 | Initial spec |
```
</details>
---
## CLI Reference
```
specsync [command] [flags]
```
### Commands
| `check` | Validate all specs against source code **(default)** |
| `coverage` | File and module coverage report |
| `generate` | Scaffold specs for modules missing one (`--provider` for AI-powered content) |
| `score` | Quality-score spec files (0–100) with improvement suggestions |
| `mcp` | Start MCP server for AI agent integration (Claude Code, Cursor, etc.) |
| `init` | Create default `specsync.json` |
| `watch` | Live validation on file changes (500ms debounce) |
### Flags
| `--strict` | Warnings become errors (recommended for CI) |
| `--require-coverage N` | Fail if file coverage < N% |
| `--root <path>` | Project root (default: cwd) |
| `--provider <name>` | AI provider: `auto`, `anthropic`, `openai`, or `command`. `auto` detects installed provider. Without `--provider`, generate uses templates only. |
| `--json` | Structured JSON output |
### Exit Codes
| `0` | All checks passed |
| `1` | Errors, strict warnings, or coverage below threshold |
---
## GitHub Action
Available on the [GitHub Marketplace](https://github.com/marketplace/actions/spec-sync). Auto-detects OS/arch, downloads the binary, runs validation.
### Inputs
| `version` | `latest` | Release version to download |
| `strict` | `false` | Treat warnings as errors |
| `require-coverage` | `0` | Minimum file coverage % |
| `root` | `.` | Project root directory |
| `args` | `''` | Extra CLI arguments |
### Workflow example
```yaml
name: Spec Check
on: [push, pull_request]
jobs:
specsync:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: CorvidLabs/spec-sync@v1
with:
strict: 'true'
require-coverage: '100'
```
---
## Configuration
Create `specsync.json` in your project root (or run `specsync init`):
```json
{
"specsDir": "specs",
"sourceDirs": ["src"],
"schemaDir": "db/migrations",
"requiredSections": ["Purpose", "Public API", "Invariants", "Behavioral Examples", "Error Cases", "Dependencies", "Change Log"],
"excludeDirs": ["__tests__"],
"excludePatterns": ["**/__tests__/**", "**/*.test.ts", "**/*.spec.ts"],
"sourceExtensions": [],
"aiCommand": "claude -p --output-format text",
"aiTimeout": 120
}
```
| `specsDir` | `string` | `"specs"` | Directory containing `*.spec.md` files |
| `sourceDirs` | `string[]` | `["src"]` | Source directories for coverage analysis |
| `schemaDir` | `string?` | — | SQL schema dir for `db_tables` validation |
| `schemaPattern` | `string?` | `CREATE TABLE` regex | Custom regex for table name extraction |
| `requiredSections` | `string[]` | 7 defaults | Markdown sections every spec must include |
| `excludeDirs` | `string[]` | `["__tests__"]` | Directories excluded from coverage |
| `excludePatterns` | `string[]` | Common test globs | File patterns excluded from coverage |
| `sourceExtensions` | `string[]` | All supported | Restrict to specific extensions (e.g., `["ts", "rs"]`) |
| `aiCommand` | `string?` | `claude -p ...` | Command for `generate --provider command` (reads stdin prompt, writes stdout markdown) |
| `aiTimeout` | `number?` | `120` | Seconds before AI command times out per module |
---
## Spec Generation
`specsync generate` scans your source directories, finds modules without spec files, and scaffolds `*.spec.md` files for each one.
```bash
specsync generate # Scaffold template specs for all unspecced modules
specsync generate --provider auto # Use AI to generate filled-in specs from source code
specsync coverage # See what's still missing
```
### Template mode (default)
Uses your custom template (`specs/_template.spec.md`) or the built-in default. Generates frontmatter + stubbed sections with TODOs.
### AI mode (`--provider`)
Reads your source code, sends it to an LLM, and generates specs with real content — Purpose, Public API tables, Invariants, Error Cases, all filled in from the code. No manual filling required.
The AI command is resolved in order:
1. `"aiCommand"` in `specsync.json`
2. `SPECSYNC_AI_COMMAND` environment variable
3. `claude -p --output-format text` (default, requires [Claude CLI](https://docs.anthropic.com/en/docs/claude-code))
Any command that reads a prompt from stdin and writes markdown to stdout works:
```json
{ "aiCommand": "claude -p --output-format text" }
{ "aiCommand": "ollama run llama3" }
```
Set `"aiTimeout"` in `specsync.json` to control per-module timeout (default: 120 seconds).
### Designed for AI agents
The generate command is the entry point for LLM-powered spec workflows:
```bash
specsync generate --provider auto # AI writes specs from source code
specsync check --json # validate, get structured feedback
# LLM fixes errors from JSON output # iterate until clean
specsync check --strict --require-coverage 100 # enforce full coverage in CI
```
Every output format is designed for machine consumption:
- **`--json`** on any command → structured JSON, no ANSI codes
- **Exit code 0/1** → pass/fail, no parsing needed
- **Spec files are plain markdown** → any LLM can read and write them
- **Public API tables** use backtick-quoted names → unambiguous to extract
### JSON output shapes
```json
// specsync check --json
{ "passed": false, "errors": ["..."], "warnings": ["..."], "specs_checked": 12 }
// specsync coverage --json
{ "file_coverage": 85.33, "files_covered": 23, "files_total": 27, "loc_coverage": 79.12, "loc_covered": 4200, "loc_total": 5308, "modules": [...] }
```
---
## Architecture
```
src/
├── main.rs CLI entry + output formatting
├── ai.rs AI-powered spec generation (prompt builder + command runner)
├── mcp.rs MCP server for AI agent integration (JSON-RPC stdio)
├── scoring.rs Spec quality scoring (0–100, weighted rubric)
├── types.rs Data types + config schema
├── config.rs specsync.json / specsync.toml loading
├── parser.rs Frontmatter + spec body parsing
├── validator.rs Validation + coverage computation
├── generator.rs Spec scaffolding
├── watch.rs File watcher (notify, 500ms debounce)
└── exports/
├── mod.rs Language dispatch
├── typescript.rs TS/JS exports
├── rust_lang.rs Rust pub items
├── go.rs Go uppercase identifiers
├── python.rs Python __all__ / top-level
├── swift.rs Swift public/open items
├── kotlin.rs Kotlin top-level
├── java.rs Java public items
├── csharp.rs C# public items
└── dart.rs Dart public items
```
**Design:** Single binary, no runtime deps. Frontmatter parsed with regex (no YAML library). Language backends use regex, not ASTs — works without compilers installed. Release builds use LTO + strip + opt-level 3.
---
## Contributing
1. Fork, branch (`git checkout -b feat/my-feature`), implement
2. `cargo test` + `cargo clippy`
3. Open a PR
### Adding a language
1. Create `src/exports/yourlang.rs` — return `Vec<String>` of exported names
2. Add variant to `Language` enum in `types.rs`
3. Wire extension detection + dispatch in `src/exports/mod.rs`
4. Add tests for common patterns
---
## License
[MIT](LICENSE) © [CorvidLabs](https://github.com/CorvidLabs)