zog

Zog is a Zod-shaped API over Go semantics, and the two disagree in ways that still compile. Import as z "github.com/Oudwins/zog". Three biases decide most calls:

• A remembered Zod default is a defect until checked. Fields are optional by default, z.Enum does not exist, and a schema key names a Go struct field rather than an input key.
• Parse and Validate disagree about what missing means, and that disagreement decides which tests in a chain run at all.
• Zog panics on a schema its author built wrong, and never on input data. A panic is a defect in the schema definition, fixed there.

Schema Shape

• A z.Shape key names a Go struct field, never an input key. The first letter is case-corrected, so "name" and "Name" both bind to Name. A key matching no field panics with Struct Schema Definition Error ... missing expected schema key.
• Struct tags map input keys and nothing else. Resolution runs json, form, query, or env for the source in use, then zog, then the schema key as written.
• z.Struct(...).Required() and .Optional() compile and do nothing. An optional nested struct needs z.Ptr(z.Struct(...)).NotNil().
• Wrap the schema in z.Ptr wherever the destination field is a pointer. A z.Slice(...) against a *[]T field panics with a type-cast error.
• z.Ptr carries only .NotNil(). Put Required, Default, Catch, Test, and Transform on the inner schema.
• Declare every schema once, at package level. A schema rebuilt per call costs roughly twice the time and several times the memory of a reused one, and the gap widens with the number of fields.
• Pick, Omit, Extend, and Merge return shallow copies and are not type-checked. A key naming no struct field panics at execution rather than failing to compile.

Read [${CLAUDE_SKILL_DIR}/references/schema-catalog.md] when reaching for a constructor, a validator, a test option, or an issue code that is not already in the chain — it carries every schema type with its full method set and signatures, the three option families, and the issue-code and type constants.