Extend SSR import rewriter to cover side-effect and dynamic import forms

[kojiwakayama]

Split out of #3114 so the dependency-pinning PR's "flag-off is behavior-identical to main" guarantee becomes literal. This carries the un-flagged SSR import-rewriting correctness fixes on their own, so they merge and soak independently of the 243-file pinning diff.

What changes

• rewritePathAliases / rewriteRelativeImports now also match side-effect imports (import "@/x.js") and dynamic imports (import("@/x.js")), which main silently left unrewritten — a correctness bug in SSR module resolution.
• The async path (rewriteSSRImportsCompatAsync) is rewritten from regex replaceAsync helpers to the parser-based parseImportEdits/applyImportEdits pass, which discovers all import forms in one walk.
• shouldKeepBareSpecifier matches protocols case-insensitively and keeps protocol-relative (//) URLs external.
• rewriteBareImports tolerates zero whitespace between the keyword and specifier (\s+ → \s*).

Every hunk is byte-identical to the corresponding code on phase0/dependency-pinning, so when this merges and main is merged back into that branch, these hunks drop out of #3114's diff cleanly and its remaining flag-off surface is unchanged from main.

Tests

New ssr-adapter.test.ts covering all six import forms (named / side-effect / dynamic × alias / relative) against both sync and async entrypoints, plus focused per-form unit tests. Full pre-push suite passed on push.

Part of veryfront-issue-inbox#240 Phase 0. Prerequisite for #3114.

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[Copilot]

Pull request overview

This PR extends the SSR import rewrite adapter to correctly rewrite additional import forms (side-effect and dynamic imports) and refactors the async rewrite path to use the shared parser-based import edit pass for more complete import discovery.

Changes:

• Expand alias and relative rewriting to cover side-effect imports (import "@/x.js") and dynamic imports (import("@/x.js")).
• Refactor the async SSR rewrite path to use parseImportEdits/applyImportEdits instead of regex-based async replacement.
• Adjust bare-import rewriting helpers (protocol detection and from"..." whitespace tolerance).

Verification

• Not run in this environment.
• Safest next step:
  • deno test --no-check --allow-all src/transforms/import-rewriter/ssr-adapter.test.ts
  • deno test --no-check --allow-all src/modules/server/ssr-import-rewriter.test.ts

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/transforms/import-rewriter/ssr-adapter.ts	Adds alias/relative coverage for side-effect and dynamic imports; switches async rewriting to parser-based import edits; tweaks bare import handling.
src/transforms/import-rewriter/ssr-adapter.test.ts	Adds coverage for the newly supported import forms across sync and async SSR rewrite entrypoints.

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[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (3)

src/transforms/import-rewriter/ssr-adapter.ts:276

• Async rewriting uses /^(?:\.\.?\/|\/)[^?#]+\.js$/ to identify relative imports, which also matches protocol-relative URLs like //example.com/mod.js. That would incorrectly rewrite external imports. Make the leading / branch reject a second /.

    const rewrite = specifier.startsWith("@/")
      ? buildAliasRewrite(specifier.slice(2), options)
      : /^(?:\.\.?\/|\/)[^?#]+\.js$/.test(specifier)
      ? buildRelativeRewrite(specifier)

src/transforms/import-rewriter/ssr-adapter.ts:217

• RELATIVE_IMPORT_PATTERNS treats any specifier starting with / as a local relative import, which also matches protocol-relative URLs like "//example.com/mod.js". That would incorrectly append ?ssr=...&v=... and break external URL imports. Exclude protocol-relative (//) here so only true root-relative paths (/foo.js) are rewritten.

This issue also appears on line 273 of the same file.

const RELATIVE_IMPORT_PATTERNS = [
  /(\bfrom\s+)["']((?:\.\.?\/|\/)[^"']+\.js)["']/g,
  /(\bimport\s+)["']((?:\.\.?\/|\/)[^"']+\.js)["']/g,
  /(\bimport\s*\(\s*)["']((?:\.\.?\/|\/)[^"']+\.js)["']/g,
];

src/transforms/import-rewriter/ssr-adapter.test.ts:86

• There’s no test ensuring protocol-relative specifiers (//example.com/...) are left untouched. This is important because the relative-import rewrite patterns treat leading / as internal and can accidentally rewrite protocol-relative URLs. Adding sync + async assertions here would prevent regressions.

  it("keeps mixed-case protocol URLs external", () => {
    const code = `import x from "HTTPS://example.com/mod.js";`;
    assertEquals(rewriteSSRImportsCompat(code, opts), code);
  });