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Malte Ubl 5cc3babc73 Add the ProgramLifetime contract: classes whose instances live until exit skip reference counting and cycle collection

`class Node implements ProgramLifetime` (@scriptc/types, import type only, erased for Node) promises that instances of the class and of its subclasses are kept until the program exits. scriptc then creates them immortal: `new` stores rc = SIZE_MAX and allocates no collector header, the class's retain and release entry points are empty (so reference counting on every static type of the hierarchy folds away), and the cycle analysis treats the hierarchy as a leaf, which untraces types that only reached it. Immortal objects are already part of every RC, collector, weak-collection and publication contract (static literals, published graphs).

The promise only changes memory use; SC7007 refuses it where something else could observe it: on a class that is not the root of its hierarchy (including built-in bases), in library builds, and on classes whose instances can be published to other threads. SC7006 reports the marker outside a class's implements clause.

tsc-ts with nine roots marked (Node, NodeList, FlowNode, Symbol, Type, Signature, IndexInfo, SymbolLinks, NodeLinks): single-threaded wall -25.8% Excalidraw, -22.2% TypeORM, -25.9% self-check, -28.5% Sentry; peak RSS -6.5% to -16.5%; identical diagnostics.

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index.d.ts

Add the ProgramLifetime contract: classes whose instances live until exit skip reference counting and cycle collection

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package.json

wip: contract types prototype

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README.md

Add the ProgramLifetime contract: classes whose instances live until exit skip reference counting and cycle collection

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README.md

@scriptc/types

Contract types for scriptc: type aliases with no meaning in TypeScript or Node.js that scriptc checks as extra promises. Import them with import type, which TypeScript erases, so Node.js never loads this package.

import type { Immutable, Int32, NoThrow } from "@scriptc/types";

const KEYWORDS: Immutable<Map<string, number>> = new Map([["const", 1]]);

class Token {
  pos: Int32 = 0;
}

function isLetter(ch: number): NoThrow<boolean> {
  return (ch >= 97 && ch <= 122) || (ch >= 65 && ch <= 90);
}

Contracts

NoThrow<T> on a function's return type: the function never throws. Callers need no exception checks.
Int32 on a parameter, variable, class instance field or function result: every stored value is a signed 32-bit integer by construction (an integer literal in range, a bitwise result such as x | 0, Math.imul, another Int32, or arithmetic scriptc can bound). The slot is stored as a 32-bit integer.
Immutable<T> on a parameter, variable, class instance field or function result: a deep read-only view, and no code writes to the value through any reference. A module constant built from literals becomes immortal data.
ProgramLifetime in a class's implements clause: instances of the class and its subclasses are never freed, so scriptc skips reference counting and cycle collection for them. Memory only: discarded instances are not reclaimed.

scriptc proves each contract or rejects the program with a diagnostic (SC7001-SC7007) that explains why it does not hold. A program that compiles behaves exactly as under Node.js. See https://scriptc.dev/docs/contracts.