Release 1.20.0

What's New

New reply Statement

New language construct for query handlers to send results back
to the sender without needing to know the sender's identity.

on query GetOrder {
  reply result OrderResult
}

• Syntax: reply result SomeResult (or any message ref)
• Classified as an executable statement for handler completeness
• Query completeness check now accepts reply as satisfying
  the query→result requirement
• Full support: parser, AST, EBNF, BAST (subtype 15), prettify,
  resolution, validation, and diagrams

Extended require Statement

The require statement now accepts either a literal string
condition or a named invariant reference:

invariant BalanceNonNegative is "balance >= 0"
handler H is {
  on command Withdraw {
    require invariant BalanceNonNegative
    // ... or the original form:
    require "amount > 0"
  }
}

• New InvariantRef type in AST
• Invariants defined but not referenced by any require invariant
  statement produce a UsageWarning
• BAST subtype 14 format updated (condition-kind byte added)

New auto-id Entity Option

entity Order is { ... } with { option auto-id }

Instructs the entity to automatically obtain a unique ULID at
instantiation time. The entity must still define an Id type so
it can be referenced in messages and state fields.

New Validation Checks

Entity checks:

• Entity Id type scope verification (three-level):
  • Inside entity body: warns to move to containing context
  • In containing context: correct, no warning
  • At domain level or beyond: warns scope is too broad
  • Not defined at all: warns missing
• Event-sourced entity command handlers must emit events
• Entities without query handlers flagged

Saga checks:

• Saga step do-statements must contain tell command to
  effect state changes

Handler checks:

• Empty on other clauses flagged (silently discards messages)

Streamlet checks:

• Flow/Split/Router handlers must send to their outlets
• Source streamlets must have on init or on other to
  generate data

Type checks:

• Command types with no fields (skips placeholder definitions)
• Event types not produced by any handler
• Query types without corresponding result types (and vice versa)

BAST Format

FORMAT_REVISION bumped to 6. RequireStatement wire format changed
(added condition-kind byte) and ReplyStatement is new subtype 15.
Old BAST files are incompatible with this revision.

Compatibility

• New language features: reply statement, require invariant
  form, auto-id option — all additive
• BAST: Breaking change (revision 5 → 6), old .bast files
  must be regenerated
• All existing APIs remain unchanged