Per-folder MODULE.md codemod for TypeScript codebases. Generates structured specs from source + JSDoc directives + Effect Schema + fast-check property tests. Validates type-coverage, precondition-pass-rate, and branch-coverage-from-spec-tests as hard CI gates.

Status: early package. Public contracts, CLI surface, and property metadata are defined; mode implementations may still be incomplete.

pnpm add -D @chughtapan/safer-spec-development
# Onboard the first folder via the safer-spec-init coding-agent skill (see below).
pnpm safer-spec generate                       # regenerate MODULE.md per folder
pnpm test                                      # property tests; reporter writes execution sidecars
pnpm safer-spec validate --implemented         # CI gate (consumes execution sidecars)

validate --implemented reads per-folder .safer-spec/<slug>.execution.json files written by the package's Vitest reporter. Register it in your vitest.config.ts:

import { defineConfig } from "vitest/config";
import { SaferSpecExecutionReporter } from "@chughtapan/safer-spec-development/reporter";

export default defineConfig({
  test: {
    reporters: ["default", new SaferSpecExecutionReporter()],
  },
});

Import the reporter from the dedicated /reporter subpath, not the package root. The root barrel pulls in itSpec, which transitively imports vitest's test API — Vitest forbids that from a config file and will throw Vitest failed to access its internal state.

The reporter writes one sidecar per folder whose tests ran. Validate compares the sidecar's property-id set against the folder's current implemented properties so a stale sidecar (test set changed since the last run) fails as MissingImplError.

safer-spec.config.json can keep independent trees such as vendored packages or generated workspaces out of the current project's source and folder graph:

{
  "excludeRootPrefixes": ["vendor", "generated/sdk"]
}

Entries are non-empty root-relative POSIX paths. Matching is path-segment aware: vendor excludes vendor and vendor/**, but not vendor-tools. Absolute paths, backslashes, and . / .. segments fail configuration loading. An excluded package can still run safer-spec from its own root; only the configuration in the current working root applies.

safer-spec generate [--folder X] [--write|--dry-run] [--watch]
safer-spec validate [--folder X] [--planned|--implemented]
safer-spec doctor                              health check
safer-spec explain <error-code>                error docs
safer-spec --version
safer-spec --help

Folder onboarding (init) and format-version migration (migrate) are not CLI commands — they ship as coding-agent skills in skills/:

• skills/safer-spec-init — scaffold a folder's first MODULE.md + property-test stub. The agent reads the existing index.ts (if any), picks the right runtime-named export to bind the stub against, and writes both files.
• skills/safer-spec-migrate — walk committed SPEC artifacts for format-version transitions; produces a per-file diff for human review.

These flows depend on judgment (which export is value-bearing on a given barrel; which format-version diffs need human eyes) that a regex / ts-morph picker baked into the CLI handles unreliably — so they live as SKILL docs a coding agent reads and executes.

See docs/DESIGN.md for the architecture.