check object shorthand: deep should default to true

[DmitrySharabin]

Problem

The default check function (equals) is deep — it's defined as deep(shallowEquals()). But when using the object shorthand to customize check behavior, deep previously defaulted to false (no default was set in the destructuring). This creates a usability cliff: the moment a user customizes check via object shorthand, they silently lose deep comparison unless they explicitly add deep: true.

Example

// Default check — deep comparison, works on nested objects
{
    run: () => ({ a: { b: 1 } }),
    expect: { a: { b: 1 } },
    // ✅ passes — default equals is deep
}

// Object shorthand — loses deep comparison
{
    run: () => ({ a: { b: 1 } }),
    expect: { a: { b: 1 } },
    check: { subset: true },
    // ❌ fails — shallowEquals can't compare objects by structure
}

// Must explicitly opt in
{
    run: () => ({ a: { b: 1 } }),
    expect: { a: { b: 1 } },
    check: { subset: true, deep: true },
    // ✅ passes
}

Docs mismatch

docs/define/README.md states deep defaults to false. PR #153 changed the code to default to true, which matches user expectations (consistent with the default equals check) but contradicts the docs.

Proposed fix

• Default deep to true in the object shorthand (as PR Lazy property resolution and accessor support (#152) #153 already does)
• Update docs/define/README.md to document deep defaulting to true

Co-Authored-By: Claude Opus 4.6 (1M context) noreply@anthropic.com

[DmitrySharabin]

Not an issue. When using the object shorthand to configure check, the author is already being explicit about comparison behavior — requiring deep: true to be stated explicitly is consistent with that. The docs correctly document deep defaulting to false.