fix(extension): replace dynamic import() with static import in scanner

[JackKuo-tw]

Problem

Clicking the extension icon fails with:

WASM scanner is not built. Run "sh extension/build-wasm.sh" before loading the extension.
import() is disallowed on ServiceWorkerGlobalScope by the HTML specification.

This happens even after a successful WASM build.

Root Cause

src/scanner.js loaded the WASM ES module via a dynamic import():

const wasmModule = await import("../dist/zhtw_mcp_wasm.js");

The HTML specification forbids dynamic import() inside a Service Worker global scope. Since background.js runs as an MV3 module service worker, this call fails at runtime.

Fix

Replace the runtime dynamic import() with a static top-level import, which is permitted in module service workers declared with "type": "module":

// Before — dynamic, forbidden in SW
const wasmModule = await import("../dist/zhtw_mcp_wasm.js");
await wasmModule.default(wasmUrl);
scanTextBinding = wasmModule.scan_text;

// After — static, allowed in module SW
import init, { scan_text } from "../dist/zhtw_mcp_wasm.js";
await init({ module_or_path: wasmUrl });

The scanTextBinding indirection is removed since scan_text is now a direct static import.

Closes #83

[cubic-dev-ai]

1 issue found across 1 file

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="extension/src/scanner.js">

<violation number="1" location="extension/src/scanner.js:1">
P1: Static top-level import of WASM module bypasses graceful error handling — a missing or invalid WASM bundle now crashes the service worker at module load time instead of being caught and reported as a user-friendly error.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P1: Static top-level import of WASM module bypasses graceful error handling — a missing or invalid WASM bundle now crashes the service worker at module load time instead of being caught and reported as a user-friendly error.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At extension/src/scanner.js, line 1:

<comment>Static top-level import of WASM module bypasses graceful error handling — a missing or invalid WASM bundle now crashes the service worker at module load time instead of being caught and reported as a user-friendly error.</comment>

<file context>
@@ -1,20 +1,18 @@
-let wasmModulePromise;
-let scanTextBinding;
+import init, { scan_text } from "../dist/zhtw_mcp_wasm.js";
+
+let initPromise;
</file context>

[JackKuo-tw]

@doggy8088 could you help to verify this fix?

[doggy8088]

Thanks for the fix. I reviewed this PR and the direction looks correct.

Chrome Extension MV3 module service workers support top-level static import, but they do not support dynamic import(). Since background.js is registered as a module service worker via "type": "module", the previous await import("../dist/zhtw_mcp_wasm.js") path can fail in the service worker environment. Replacing it with a static import from ../dist/zhtw_mcp_wasm.js matches Chrome’s service worker loading model.

I also checked the review concern about error handling. It is true that if extension/dist/zhtw_mcp_wasm.js is missing, a static import fails during service worker module loading, so the old user-friendly scanText() error path cannot run. I do not think that should block this PR: an extension loaded without the generated WASM bundle is already not in a valid runnable state, and the extension packaging workflow builds WASM first and includes extension/dist/*.js and *.wasm in the package.

So I think this PR is the right fix for #83. If we want to improve the developer experience further, that can be handled separately by making the build/package step or README more explicit about requiring sh extension/build-wasm.sh before loading the unpacked extension.

LGTM.

[jserv]

Thank @JackKuo-tw for contributing!