feat: confstash — standardized project config loading (discovery, extends/presets, layered merge with provenance)

.github/workflows/ci.yml

@@ -48,6 +48,7 @@ jobs:
         package:
           - appstash
           - clean-ansi
+          - confstash
           - fetch-api-client
           - find-and-require-package-json
           - http-errors

README.md

@@ -21,6 +21,7 @@ A comprehensive collection of TypeScript utilities for working with schemas, JSO
 |---------|-----|--------|-------------|
 | **appstash** | [![npm](https://img.shields.io/npm/v/appstash.svg)](https://www.npmjs.com/package/appstash) | [GitHub](./packages/appstash) | Simple, clean application directory resolution |
 | **clean-ansi** | [![npm](https://img.shields.io/npm/v/clean-ansi.svg)](https://www.npmjs.com/package/clean-ansi) | [GitHub](./packages/clean-ansi) | Remove ANSI escape codes from strings |
+| **confstash** | [![npm](https://img.shields.io/npm/v/confstash.svg)](https://www.npmjs.com/package/confstash) | [GitHub](./packages/confstash) | Standardized project configuration loading — config files, rc files, presets, and layered merge with provenance |
 | **create-gen-app** | [![npm](https://img.shields.io/npm/v/create-gen-app.svg)](https://www.npmjs.com/package/create-gen-app) | [GitHub](./packages/create-gen-app) | Clone and customize template repositories with variable replacement |
 | **inquirerer** | [![npm](https://img.shields.io/npm/v/inquirerer.svg)](https://www.npmjs.com/package/inquirerer) | [GitHub](./packages/inquirerer) | TypeScript-first library for building beautiful CLI interfaces with interactive prompts |
 | **jsonldjs** | [![npm](https://img.shields.io/npm/v/jsonldjs.svg)](https://www.npmjs.com/package/jsonldjs) | [GitHub](./packages/jsonld-tools) | Powerful JSON-LD builder with comprehensive filtering and subgraph extraction |

packages/confstash/README.md

@@ -0,0 +1,163 @@
+# confstash
+
+<p align="center">
+  <img src="https://raw.githubusercontent.com/constructive-io/constructive/refs/heads/main/assets/outline-logo.svg" height="250">
+  <br />
+    <strong>standardized project configuration loading</strong>
+  <br />
+  <br />
+  Config files, rc files, presets, and layered merge with provenance
+  <br />
+  <br />
+  <a href="https://github.com/constructive-io/dev-utils/actions/workflows/ci.yml">
+    <img height="20" src="https://github.com/constructive-io/dev-utils/actions/workflows/ci.yml/badge.svg" />
+  </a>
+  <a href="https://github.com/constructive-io/dev-utils/blob/main/LICENSE">
+    <img height="20" src="https://img.shields.io/badge/license-MIT-blue.svg"/>
+  </a>
+</p>
+
+Standardized project configuration loading for CLI tools — the project-level complement to [`appstash`](../appstash) (user-level directories).
+
+Give it a tool name and it discovers `mytool.config.{ts,js,mjs,cjs}`, `.mytoolrc{,.json,.yaml,.yml,.js}`, `mytool.json`, and `package.json` keys via walk-up search, resolves `extends`/preset chains, and merges layered configuration with per-key provenance:
+
+```
+defaults -> presets (extends) -> user stash -> project file -> env vars -> runtime overrides
+```
+
+## Installation
+
+```bash
+npm install confstash
+```
+
+## Features
+
+- **Walk-up discovery**: finds config in the current directory or any parent
+- **Every format**: `.config.ts/js/mjs/cjs` modules, rc files (JSON/YAML), JSON, `package.json` keys
+- **Presets & extends**: named presets, relative paths, or npm packages — recursively, with cycle detection
+- **Layered merge**: deterministic precedence with `replace` or `concat` array strategies
+- **Provenance**: `explainSync()` tells you which layer supplied every value (`--print-config` UX)
+- **Sync and async**: fully synchronous path for CLIs (ESM configs require `load()`)
+- **User layer**: optional `~/.<tool>/config/config.json` layer via appstash
+- **Typed**: `defineConfig<T>()` + generic loader for full type safety
+
+## Usage
+
+### Basic Usage
+
+```typescript
+import { createConfigLoader } from 'confstash';
+
+interface MyConfig {
+  level: string;
+  rules: Record<string, string>;
+}
+
+const loader = createConfigLoader<MyConfig>({
+  tool: 'mytool',
+  defaults: { level: 'medium', rules: {} }
+});
+
+const { config, filepath, layers, isEmpty } = loader.loadSync();
+// or: await loader.load()  — also supports .mjs / ESM configs
+```
+
+### Presets and extends
+
+```typescript
+const loader = createConfigLoader<MyConfig>({
+  tool: 'mytool',
+  presets: {
+    'mytool:recommended': { level: 'medium', rules: { A1: 'error' } },
+    'mytool:strict': { extends: 'mytool:recommended', level: 'high' }
+  }
+});
+```
+
+```jsonc
+// .mytoolrc.json
+{
+  "extends": "mytool:strict",     // or "./team-preset.js", or "some-npm-pkg"
+  "rules": { "A1": "off" }
+}
+```
+
+### Typed config authoring
+
+```typescript
+// mytool.config.ts
+import { defineConfig } from 'confstash';
+
+export default defineConfig({
+  extends: 'mytool:recommended',
+  level: 'high'
+});
+```
+
+### Environment and CLI layers
+
+```typescript
+const loader = createConfigLoader<MyConfig>({
+  tool: 'mytool',
+  envLayer: (env) => (env.MYTOOL_LEVEL ? { level: env.MYTOOL_LEVEL } : {}),
+  userStash: true // include ~/.mytool/config/config.json (via appstash)
+});
+
+const { config } = loader.loadSync({
+  overrides: parsedCliFlags // highest precedence
+});
+```
+
+### Provenance / print-config
+
+```typescript
+for (const entry of loader.explainSync()) {
+  console.log(`${entry.path} = ${JSON.stringify(entry.value)}  (${entry.source}: ${entry.origin})`);
+}
+// level = "high"        (file: /repo/mytool.config.ts)
+// rules.A1 = "error"    (preset: mytool:recommended)
+```
+
+### Custom search places
+
+```typescript
+// pgpm-compatible discovery
+const loader = createConfigLoader({
+  tool: 'pgpm',
+  searchPlaces: ['pgpm.config.js', 'pgpm.json'],
+  arrayMerge: 'replace'
+});
+```
+
+## API
+
+### `createConfigLoader<T>(options)`
+
+**Options:**
+- `tool` (string): tool name; drives default search places and the user stash directory
+- `searchPlaces` (SearchPlace[]): filenames or `{ packageJson: key }` entries, in precedence order
+- `defaults` (Partial<T>): lowest-precedence layer
+- `presets` (Record<string, Partial<T>>): named presets resolvable via `extends`
+- `envLayer` ((env) => Partial<T>): map environment variables into a layer
+- `userStash` (boolean): include `~/.<tool>/config/config.json` (default `false`)
+- `arrayMerge` (`'replace' | 'concat'`): array strategy (default `'replace'`)
+- `validate` ((config: T) => T | void): validate/normalize the merged result
+- `walkUp` (boolean): search parent directories (default `true`)
+
+**Returns:** `ConfigLoader<T>` with `load(params)`, `loadSync(params)`, `explainSync(params)`, `searchPlaces`.
+
+**Load params:** `cwd`, `overrides`, `configFile` (skip discovery), `env`.
+
+### Utilities
+
+- `defineConfig<T>(config)` — identity helper for typed config files
+- `defaultSearchPlaces(tool)` — the derived search place list
+- `findConfigSync(startDir, searchPlaces, walkUp?)` / `findUpDir(startDir, filename)` — discovery primitives
+- `loadFileSync(found)` / `loadFile(found)` — format-aware file loading
+- `deepMerge(target, source, arrayMerge?)` / `mergeLayers(layers)` / `explainLayers(layers)` — merge primitives
+- `ConfigLoadError` — thrown for unreadable/invalid config files
+
+## Related
+
+- [`appstash`](../appstash) — user-level directories (`~/.<tool>/{config,cache,data,logs}`) and the optional `userStash` layer