Specification Status

This specification records the accepted semantic model of VibeLang. It is not a final language standard and does not imply a conforming implementation exists.

Last reconciled with the decision ledger: August 21, 2026.

Maturity Labels

Every design rule has one of three maturity levels:

Unless a section says otherwise, statements in these specification pages summarize locked decisions. Syntax shown for a directional feature is informative.

Normative Terms

The words MUST, MUST NOT, SHOULD, SHOULD NOT, and MAY describe intended conformance requirements. Because the grammar and compiler contract are incomplete, these terms apply only to behavior marked locked.

Examples are non-normative unless the surrounding text states otherwise.

Conformance Targets

VibeLang defines several distinct subjects of conformance:

• a source implementation parses and checks .vibe programs
• the TypeScript backend preserves TypeScript-compatible source behavior and emits TypeScript/JavaScript artifacts
• a native backend emits near-native code and supplies the VibeLang runtime
• a Wasm backend emits WebAssembly for a declared host contract
• a durable runtime executes compiler-produced Flow plans and Action protocols

No conforming compiler has been released. The repository prototype is not a reference implementation.

Source of Truth

During early design, accepted decisions live in the decision ledger. The durable execution draft expands the distributed runtime model.

When these pages conflict with the ledger, the ledger wins until the specification is updated. A future complete specification will replace that arrangement.

Specification Map

• Compatibility defines the TypeScript interop boundary and target model.
• Type System defines function channels, optionals, and portability classification.
• Failure Semantics defines failures, defects, propagation, and recovery.
• Requirements defines Context capabilities, inferred requirement rows, and layer satisfaction.
• Control Flow defines expression forms and cleanup direction.
• Comptime defines the imported compiler intrinsic, phase evaluation, and tracked compiler input.
• Durable Execution defines the imported durable intrinsic, Actions, static Flow lowering, non-executing plan/preview, and runtime guarantees.

Known Gaps

The following areas prevent a complete normative grammar and conformance suite:

1. dynamic TypeScript feature classification
2. assertion and cast semantics
3. nested Optional normalization and additional implicit conversions
4. layer lifecycle and lowering
5. shared checked IR and compiler plugin seams
6. loader registration and built-in asset module shapes
7. durable IDs, loops, sequencing, encoding, and migration
8. exact standard-library and agent-library APIs