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fix(bundler): runtime mode opt-in, ASI-safe joinJsChunks, prune dead subs

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Per @vai-bot's review on hf#641:

Important #1: dead `src=""` substitution sites
=============================================

Now that `bundleToSingleHtml` inlines the runtime IIFE by default, the empty
`src=""` placeholder is never emitted in the no-env-var path — the 5 downstream
substitution sites that grep for `src=""` were dead.

Two of them (studio dev server + studio vite preview) genuinely WANT the
placeholder so they can hot-reload a local /api/runtime.js endpoint without
re-inlining ~150 KB on every composition edit. Three of them (CLI validate,
snapshot, layout) were just doing the same inlining the bundler already does.

Resolution:
- Add a `runtime: "inline" | "placeholder"` option to `BundleOptions`. Default
  is "inline" (matches the self-contained-bundle promise the function name
  makes). The two studio surfaces explicitly pass `{ runtime: "placeholder" }`
  to opt in.
- studioServer.ts + studio/vite.config.ts: pass the option, keep their
  existing string-replace logic unchanged.
- validate.ts + snapshot.ts + layout.ts: delete the now-redundant runtime
  substitution code (regex never matches the new inlined-runtime shape).

Important #2: joinJsChunks ASI hazard
======================================

The new helper appended `;` to chunks not already ending in `;` and joined
on `\n`. If a chunk ended with a `// line comment`, the appended semicolon
was eaten by the comment, leaving the next chunk's first statement attached
to the previous chunk's last expression — exactly the ASI hazard the helper
exists to prevent.

Fix: append `\n;` instead of `;` for chunks not already terminated. The
newline closes the line comment, the standalone `;` becomes the statement
separator. For typical chunks (already ending in `;`), output is unchanged
— still clean `\n`-joined chunks with no bare-semicolon lines.

Also added a trailing `;` to `wrapScopedCompositionScript`'s IIFE close
(`})()` → `})();`) so composition scripts join cleanly without falling
through to the `\n;` fallback.

New test: regression guard at the chunk boundary verifies every inline
script body in the bundle parses cleanly via esbuild even when a source JS
file ends with a line comment.

Verification
============

- `bun run --filter @hyperframes/core test` — 653/653 pass
- `bun run --filter @hyperframes/cli test` — 243/243 pass
- `bun run --filter @hyperframes/{core,cli,studio} typecheck` — clean
- `bunx oxfmt --check` + `bunx oxlint` on all touched files — clean

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Rames Jusso
2026-05-06 04:37:04 +00:00
co-authored by Claude Opus 4.7
parent af2f727b3f
commit dfca302d37
8 changed files with 103 additions and 73 deletions
Download Patch File Download Diff File Expand all files Collapse all files
packages/core/src/compiler/compositionScoping.ts
+1 -1
View File
@@ -286,5 +286,5 @@ ${source}
};
__hfFindRoot();
__hfRun();
})()`;
})();`;
}
packages/core/src/compiler/htmlBundler.test.ts
+34
View File
@@ -82,6 +82,40 @@ describe("bundleToSingleHtml", () => {
expect(innerLength).toBeGreaterThan(1000);
});
it("preserves chunk integrity when a chunk ends with a line comment (ASI hazard guard)", async () => {
// Regression guard for the joinJsChunks helper. If a chunk ends with `// ...`
// and we naively appended `;` on the same line, the appended semicolon would
// be eaten by the comment, leaving the next chunk's first statement attached
// to the previous chunk's last expression. Verify the helper appends `\n;`
// instead so the comment terminates and the semicolon stands alone.
const dir = makeTempProject({
"index.html": `<!doctype html>
<html><body>
<div data-composition-id="root" data-width="320" data-height="180"></div>
<script src="local-a.js"></script>
<script src="local-b.js"></script>
<script>window.__timelines = window.__timelines || {}; window.__timelines.root = {}</script>
</body></html>`,
// Chunk A ends with a // line comment — without the \n separator before
// the appended ;, that ; would be eaten by the comment.
"local-a.js": "window.__a = 1 // trailing line comment",
"local-b.js": "window.__b = 2",
});
const bundled = await bundleToSingleHtml(dir);
// Run every inline script body through esbuild; if the line comment ate
// the separator, parse would fail with an unexpected-token error somewhere
// around the chunk boundary.
const { transformSync } = await import("esbuild");
const re = /<script\b[^>]*>([\s\S]*?)<\/script>/g;
let m: RegExpExecArray | null;
while ((m = re.exec(bundled)) !== null) {
const body = m[1];
if (!body || !body.trim()) continue;
expect(() => transformSync(body, { loader: "js", minify: false })).not.toThrow();
}
});
it("does not produce stray bare-semicolon lines between concatenated JS chunks", async () => {
// Regression guard: hf#XXX. Earlier the bundler joined script chunks with
// `\n;\n`, which produces a lone `;` on its own line between chunks. Valid
packages/core/src/compiler/htmlBundler.ts
+43 -12
View File
@@ -27,20 +27,24 @@ function getRuntimeScriptUrl(): string {
return configured || DEFAULT_RUNTIME_SCRIPT_URL;
}
function injectInterceptor(html: string): string {
function injectInterceptor(html: string, runtimeMode: "inline" | "placeholder" = "inline"): string {
const sanitized = stripEmbeddedRuntimeScripts(html);
if (sanitized.includes(RUNTIME_BOOTSTRAP_ATTR)) return sanitized;
// When a runtime URL is configured (HYPERFRAME_RUNTIME_URL env var), the bundle
// points at it via src=… and the host page serves the script. When no URL is
// configured — the common `bundleToSingleHtml` use case — inline the runtime
// body so the bundle is genuinely self-contained. An empty src="" attribute
// would otherwise resolve to the page URL and trigger an infinite-fetch loop.
// Three modes for the runtime <script>:
// 1. HYPERFRAME_RUNTIME_URL env var set → emit src="<url>" (production CDN deploy).
// 2. runtime: "placeholder" passed → emit src="" for the caller to substitute
// (studio + vite preview hot-load a local
// runtime endpoint via string replace).
// 3. runtime: "inline" (default) → embed the IIFE body directly so the
// bundle is genuinely self-contained.
const runtimeScriptUrl = getRuntimeScriptUrl();
let tag: string;
if (runtimeScriptUrl) {
const escaped = runtimeScriptUrl.replace(/"/g, "&quot;");
tag = `<script ${RUNTIME_BOOTSTRAP_ATTR}="1" src="${escaped}"></script>`;
} else if (runtimeMode === "placeholder") {
tag = `<script ${RUNTIME_BOOTSTRAP_ATTR}="1" src=""></script>`;
} else {
const inlinedRuntime = getHyperframeRuntimeScript();
tag = `<script ${RUNTIME_BOOTSTRAP_ATTR}="1">${inlinedRuntime}</script>`;
@@ -293,16 +297,27 @@ function coalesceHeadStylesAndBodyScripts(document: Document): void {
}
/**
* Concatenate JS chunks safely. Each chunk gets a trailing `;` if it doesn't
* already end in one, so the joined output never inserts a stray bare-semicolon
* line between chunks (the `\n;\n` separator pattern produces a lone `;` on its
* own line, which is valid JS but reads as a code smell to most linters).
* Concatenate JS chunks safely. Goals:
* - Each chunk's last statement is terminated, so joining can't introduce ASI
* surprises (e.g. `a()` followed by `(b)()` — the second chunk would parse
* as a call on the first's return value).
* - In the common case (chunk already ends with `;` — typical of esbuild
* output and IIFE-wrapped composition scripts ending in `})();`), the join
* produces clean output: chunks separated by `\n` with no stray bare
* semicolon lines.
* - Defensive against trailing line comments. If a chunk ends with `// ...`
* and we appended `;` on the same line, the appended semicolon would be
* swallowed by the comment, leaving the next chunk's first statement
* attached to the previous chunk's last expression — exactly the ASI
* hazard this helper exists to prevent. So when a chunk doesn't already
* end in `;`, we append `\n;` instead — the newline closes any line
* comment, and the standalone `;` becomes the statement separator.
*/
function joinJsChunks(chunks: string[]): string {
return chunks
.map((chunk) => chunk.trim())
.filter((chunk) => chunk.length > 0)
.map((chunk) => (chunk.endsWith(";") ? chunk : chunk + ";"))
.map((chunk) => (chunk.endsWith(";") ? chunk : chunk + "\n;"))
.join("\n");
}
@@ -319,6 +334,22 @@ function stripJsCommentsParserSafe(source: string): string {
export interface BundleOptions {
/** Optional media duration prober (e.g., ffprobe). If omitted, media durations are not resolved. */
probeMediaDuration?: MediaDurationProber;
/**
* How to handle the HyperFrames runtime <script> tag. Default: `"inline"`.
*
* - `"inline"` — embed the runtime IIFE body directly into the bundle. Produces
* genuinely self-contained HTML. Right for CLI render output, validate,
* snapshot, and any "ship a single .html file" use case.
* - `"placeholder"` — emit `<script ... src=""></script>` so the caller can
* substitute it with a real URL via string replace. Used by the dev studio
* server and vite preview to point at a local runtime endpoint, which keeps
* the runtime cacheable across hot-reloads instead of re-inlining ~150 KB
* on every change.
*
* The `HYPERFRAME_RUNTIME_URL` env var, when set, takes precedence over both
* modes and emits `<script ... src="<URL>">` directly.
*/
runtime?: "inline" | "placeholder";
}
/**
@@ -347,7 +378,7 @@ export async function bundleToSingleHtml(
);
}
const withInterceptor = injectInterceptor(compiled);
const withInterceptor = injectInterceptor(compiled, options?.runtime ?? "inline");
const document = parseHTMLContent(withInterceptor);
// Inline local CSS