Program-lifetime instances were created with rc == SIZE_MAX, which every runtime contract reads as "published": the frozen-object guards throw on stores, postMessage and workerData share the object by pointer instead of cloning it, and the publish walker stops there. So programs that publish could not use ProgramLifetime (SC7007 refused it), and an unpublished instance posted to a worker would have been shared instead of cloned.
They are now created with the midpoint count 2^63 (2^31 on 32-bit targets). Only the class's empty retain and release helpers count references on these types, so nothing ever changes or frees that count; the midpoint keeps even an unpaired generic retain or release away from 0 and SIZE_MAX. Until the program publishes an instance it is an ordinary mutable, thread-local object to every runtime contract: stores succeed, postMessage clones it. Publication marks it SIZE_MAX like any object it reaches (the visited mark, logged and restored when a refusal undoes the publish), after which the frozen guards throw Node's TypeErrors and other threads read it by pointer. No header, extra word, runtime change or new instruction: the count itself is the published mark. The cycle analysis keeps the hierarchies untraced, so the collector never visits an instance, as for every untraced class.
SC7007 no longer refuses program-lifetime classes reachable from a publish() call; it still requires a root class in an executable. Without the marker nothing changes: tsc-ts best-v7 built with and without this change is byte-identical.
Tests: corpus 4634-contract-program-lifetime-publish (Node vs native): program-lifetime hierarchies with parent cycles, maps and sets of them, maps keyed by them and mortal scopes around them, published on the main thread and a worker and read on the other; writes after publication throw on both threads; unpublished instances stay writable; a refused publish leaves visited instances writable; a later publish reaches published and fresh instances; an unpublished instance in workerData is cloned. With the old SIZE_MAX count the program dies at its first constructor store. classes.test.ts covers the count on both pointer widths, the walker and the frozen guard. The contract-program-lifetime-publish diagnostics fixture is removed (the program now compiles). Docs: contracts and limitations pages, @scriptc/types.
`implements Acyclic` resolved to Record<never, never>, and the frontend
indexes implemented types as class protocols by symbol, so every Record
value in the program took checked identity (on tsc-ts: Int32 field
contracts failed with SC7003). The default is now AcyclicObject, an empty
interface only @scriptc/types declares, and type arguments in heritage
clauses are reported (they would make a class implement its own type).
Corpus 4642 stores an Acyclic class with an Int32 field in a Record.
explainCycle picks the shortest cycle through the unit and a mutable
edge (BFS distances forward and backward within the component): on
tsc-ts `Node.parent -> Node` instead of a 20-step path through the
checker.
`class C implements Acyclic`, `interface I extends Acyclic` and
`type T = Acyclic<{ ... }>` promise that no chain of references leads
from such an object back to itself. The check is the cycle analysis that
decides tracing, so a proven type carries no cycle-collector header. When
it does not hold, SC7007 shows the cycle: the path of fields, and why it
can close (a field assigned after construction, with the first such
write; an array, Map or Set; a function, dynamic or promise field; a
subclass sharing the layout). cycle-analysis.ts gains explainCycle over
the same graph with edge labels; computeTraced is unchanged.
Acyclic elsewhere is reported with SC7006. Docs, @scriptc/types,
corpus 4642, diagnostics snapshots and TypeScript baselines included.
`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.
Chris Tate