Validation and redaction

loadConfig() validates at startup and throws one ConfigError after collecting all detectable issues.

import { ConfigError } from 'typespun';

try {
  loadConfig();
} catch (error) {
  if (error instanceof ConfigError) {
    for (const issue of error.issues) {
      console.error(issue.code, issue.path, issue.message);
    }
  }
}

Issue codes are missing_value, invalid_value, unknown_override, source_read_failed, and incompatible_schema. Non-secret invalid values may include received; missing values never do.

Secret fields

Mark a leaf or object branch with @secret/@Secret(). For secret invalid values, Typespun emits the generic message Invalid value for secret field, omits received, and avoids type-specific details such as allowed enum values. Build-time defaults diagnostics identify only the file and property path.

Coercion rules

• strings remain strings, including empty strings
• numbers accept complete decimal/scientific strings and must be finite
• booleans accept true or false, case-insensitively
• string enums/literal unions require an exact, nonempty member
• arrays are JSON-parsed and every element must match the declared primitive
• typed defaults and overrides are validated without coercion

Optional object branches remain absent until any descendant resolves. Once a branch is active, all required descendants must resolve.

Related