Status: tooling experimental Target line: N/M 0.2 Last updated: 2026-07-13

Problem

N/M 0.1 workspace imports expose every top-level circuit, observable, and const. A module cannot keep implementation helpers private, so workspace, LSP, and package boundaries cannot share one explicit export contract.

Proposed syntax

module bell_library;

private const HALF = PI / 2;

private circuit prepare_phase(data: QReg<2>) {
  Ry(data[0], HALF);
}

public circuit prepare_bell(data: QReg<2>) {
  H(data[0]);
  CNOT(data[0], data[1]);
}

public observable parity = Z(data[0]) Z(data[1]);

The negotiated tooling slice accepts public and private only on circuit, observable, and const. fn main, param, executable statements, annotations, and nested declarations cannot carry visibility.

Compatibility

N/M 0.1 source remains unchanged: unqualified declarations are treated as legacy-public.
The stable parser default rejects visibility syntax with NM-PARSE-051 unless experimental.moduleVisibility is explicitly enabled.
With the flag enabled, private declarations remain available inside their source module but are excluded from use workspace.<module> expansion.
CLI callers negotiate with --experimental-module-visibility; Language Server and VS Code callers use initializationOptions.nm.experimental.moduleVisibility=true. Neither surface silently enables the proposal.
Local document symbols include private declarations. Cross-module completion, workspace symbols, definition, signature help, references, prepare-rename, and rename filter them from consumers.
Future source-version negotiation may change the default only in a new language contract; this RFC does not do so.

Non-goals in this slice

Package publication exports or cryptographic access control. Visibility is a language namespace boundary, not a security boundary.
Re-export syntax, wildcard imports, friend modules, package namespaces, or registry version syntax.
Visibility for local variables, parameters, fn main, tests, properties, or snapshots.

Promotion sequence

Parser flag and AST evidence → workspace semantic filtering → CLI/LSP/VS Code parity → cross-platform conformance fixtures → 0.2 preview evaluation. The first three stages are implemented. Promotion remains blocked on the Windows/Linux Node 20/22 matrix and later package-publication design; the 0.1 golden parser/runtime suite must remain unchanged throughout.