Runtime Request Validation

The problem

-> is a data pipe, not a type pipe. When A returns {name: "x"} and B expects struct{Description string; Tier string}, Coerce silently zeroes the mismatched fields.

A: {name: "x", tier: "pro"}
         ↓ InvokeAny → Coerce[Req_B]
B: {Description: "", Tier: "pro"}   ← name vanished, no error

The compile-time edge check in flow/pipeline_types.go catches only direct A -> B. Any projection { } or with @{ } in between disables the check, because the parser cannot see what flows through. Runtime strict closes that gap.

Four validation states

The interaction between @config:strict, :strict, and :lenient determines whether validation runs.

• No @config:strict, no :strict, no :lenient → validation does **not** run.
• @config:strict=true alone → validation runs.
• :strict alone on an atom → validation runs for that atom.
• @config:strict=true + :lenient on an atom → validation does **not** run for that atom.
• @config:strict=true + :strict + :lenient on the same atom → :lenient wins; validation does not run.

Three ways to enable

# Per file
@config:strict=true
producer -> { name: .name } -> consumer

# Per atom
producer -> { name: .name } -> consumer:strict

# Opt-out per atom (when global strict is on)
@config:strict=true
producer -> { internal_thing: .x } -> helper:lenient

Example with validate tags

Action with validate tags + strict mode = runtime validation that produces xerr.KindValidation (HTTP 400) on failure.

type CreateUserReq struct {
    Name  string `json:"name"  validate:"required,min=3"`
    Email string `json:"email" validate:"required,email"`
}

@config:strict=true

# passes
{ name: "Ada", email: "ada@nexss.dev" } -> create_user

# runtime: [Validation] validation failed
#    field "name": failed 'min' check (expected 3)
{ name: "Al", email: "ada@nexss.dev" } -> create_user

# runtime: "email" field missing
{ name: "Ada" } -> create_user