Config Loading

Purpose

A single shared routine every CLI command calls to find, load, and validate patties.config.ts. The framework spec 08-config defines the file's shape; this spec defines the CLI's resolution behavior.

Public surface

export interface ResolvedConfig { /* see framework spec 08 */ }
export interface LoadOptions {
  cwd: string
  configPath?: string         // from --config flag
  overrides?: Partial<ResolvedConfig>  // from per-command flags like --target
}

export async function loadConfig(opts: LoadOptions): Promise<ResolvedConfig>

Resolution order

1. If configPath is set, use it. Error if the file does not exist.
2. Otherwise look in cwd for patties.config.ts, then .js, then .mjs. First hit wins.
3. If nothing is found, return defaults — Patties must run with zero config.

Load

• Import the file via Bun's native TS support.
• The default export must be the object (or the result of defineConfig(...)).
• Validate with Zod; produce a normalized config.
• Apply overrides after validation, validating again (so --target node still rejects).

Caching

• Loads are not cached across CLI invocations.
• Within a single invocation (e.g. dev re-reading after a restart), the loader uses a content-hash cache to skip re-validation when the file is unchanged.

Errors

Validation errors include:

• Absolute path to the offending file.
• The path within the config (e.g. env.required[0]).
• The expected vs received value.
• A suggested fix when possible (closest legal enum value).

Acceptance criteria

• Running any command in an empty directory uses defaults without warning.
• --config ./custom.ts loads that file; if missing, the command exits 2 with the resolved path in the message.
• An invalid target value in config is caught before any build or server work begins.