Fix pi's small compile gaps

[cramforce]

The pi coding agent diagnosis turned up a set of small gaps on pi's startup, provider-stream and terminal paths. Each fix is its own commit and lands with Node-differential corpus programs, which pass in both the plain and sanitized lanes. The optional-chain miscompile from the same diagnosis lands separately (opt/optional-chain-fix).

Changes

1. Assign process.emitWarning. The assignment stores the replacement. Later process.emitWarning(...) calls apply it to their own arguments. Warnings the runtime builds itself (util.deprecate and Node's own modules) reach it as (message, type[, code]), and no report is printed. Assigning process.title already worked; the corpus program pins both.
2. Type process.getBuiltinModule results as module namespaces. Under @types/node, a string-literal id that names a supported builtin now lowers to the same namespace value an import * as binding has. This includes pi's spelling (process as P).getBuiltinModule?.("node:os") ?? null. A nullable namespace binding that has been narrowed to present uses the same member tables, and a namespace is truthy. Reading process.features as a whole value gives an object with none of the flags set, which matches the existing reads of its members.
3. for await over class instances whose [Symbol.asyncIterator] is an async generator method. This is pi-ai's EventStream, which every provider stream goes through. An async * declaration annotated with AsyncIterator, AsyncIterableIterator or AsyncIterable maps like AsyncGenerator. Boxing a class instance whose fields hold a promise now links the dynamic async unit. Without that, linking failed on EventStream's this.isComplete(event).
4. WeakMap- and WeakSet-typed class fields. These are stored in the same checked-dynamic storage that locals of those types already use.
5. chalk.bold() from TypeScript. TypeScript that imports chalk's JavaScript source types the default export as a plain function, so chalk.bold is an any member on a typed receiver. Compile chalk 5 through the dynamic object model #1309 only handled receivers that are themselves untyped, so this shape was still refused. A member the checker leaves untyped now takes the same path, which still refuses a string receiver at run time. The chalk 5 fixture now covers root, aliased and Chalk-instance bold calls.
6. Bare core-module names resolve to builtins. An installed npm string_decoder (or events, ...) no longer captures import "string_decoder", because Node checks its builtins first. Builtins that only exist with the node: prefix, such as node:test, leave their bare names to packages.
7. pi-tui terminal setup. The presence check if (process.stdin.setRawMode) now answers the method on a TTY and undefined otherwise. process.stdin.setEncoding decodes with the shared StringDecoder: a multibyte character split across reads stays whole, and the buffered tail is flushed before 'end'. String 'data' listeners are supported. process.stdout.on/once/off("resize") works, backed by a SIGWINCH listener that does not keep the event loop alive and only emits when a TTY's size actually changed.
8. delete this.stack on Error subclasses that declare a stack accessor. quickjs-wasi's JSException does this. Compiled errors keep the stack trace internally, so the delete only needs to evaluate its receiver.
9. Runtime variants for the new runtime behavior. The emitWarning replacement (item 1) and the stdin encoding, string 'data' listeners and 'resize' support (item 7) are compiled only into two new runtime-pack variants: SCR_WARNING_REPLACE of scr_async_dyn.c and SCR_STDIO_EXTENDED of scr_events.c. The link selects them when the program assigns process.emitWarning, or reaches setEncoding, a string 'data' listener or 'resize' (the compiler's warningReplace / stdioExtended link features). The default objects are byte-identical to main's, so the shared warning paths, stdin delivery and TLS layout of every other executable are unchanged. The development and sanitizer builds pass the same defines. The darwin matrix lists the variants too, so the macOS runtime pack has to be rebuilt to provide them.

Not in this PR

• A computed class field keyed by a well-known symbol ([Symbol.toStringTag] = "LRUCache", from lru-cache). Fields named with sym: need to be materialized for the dynamic view, Object.prototype.toString and inspect, and only methods support that today.
• node:sea, which pi's extension loader probes with process.getBuiltinModule("node:sea")?.isSea(), is not a supported builtin.
• this.decoder.decode(...) inside a method compiled with a dynamic this (quickjs-wasi handleHostCall). The class's dynamic view cannot expose a TextDecoder record field. Fixing it needs a dynamic handle that holds the codec record by reference. A repro is in the results directory.
• Destructuring from globalThis in TypeScript (const { X } = globalThis as unknown as T), and the local typing of evalCode() results in quickjs-wasi callers.
• Found while testing: "stack" in e is false natively for a class stack accessor, where Node answers true.

Validation

• Corpus programs 6231–6237 and the extended chalk 5 fixture pass in the plain and sanitized lanes, with 6231 and 6236 re-run against the variant runtime pack. The related existing corpus slices (async iteration, stdin, readline, tty, signals, warnings, weak collections, chalk, npm) also pass. Failures that reproduce identically on the base build were left alone: 5614, 5254, 5372, 5568, 5564 and npm node24-url-authority. These are Node 24.15 vs 24.22 differences in the sandbox.
• pnpm lint and pnpm format:check are clean. pnpm test:ts7 --baselines-only is complete. The runtime-pack, backend, executable-cache, runtime-features, validate and code-quality unit tests pass (941).
• Self-hosting: building packages/compiler/src/native/cli.ts with --emit=ir reports no diagnostics. tests/harness/self-hosting-native-driver.test.ts passed on the pre-merge tree.
• The default runtime-pack objects (.o, all flavors) built from this branch are byte-identical to origin/main's; the only additions are the warning-replace and stdio-extended variant directories (and their -workers twins).
• Zero-cost gate against origin/main 64e3ecd (benchmarks, the self-hosted compiler and the TypeScript corpus): PASS: all 2395 programs are byte-identical in IR, LLVM and release executables, with no remaining differences. Compile time: bench geomean −0.12% (CI −1.07%/+0.70%), self +0.28% (CI +0.20%/+0.46%), both within tolerance. The gate ran on the tree just before two last edits: normalizing the new link features to booleans in effectiveRuntimeFeatures (needed for self-hosting) and the matching test fixture. Those edits only touch variant selection and give the same answer for programs that do not set the features.

🤖 Generated with Claude Code

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
scriptc	Ready	Preview, v0	Oct 19, 2026 9:48pm UTC