fix(shared): preview addresses containing another URL open instead of searching

[maxwellyoung]

Typing localhost:3000/?next=https://example.com in the preview address bar starts a search instead of opening the local app. The URL normalizer mistook any embedded :// for the outer scheme.

Use the address bar's existing anchored scheme check in both helpers, preserving the outer host and path/query/fragment. Original fix by @maxwellyoung in #17943; retained after independent implementation review. Merged current main into the contributor branch without rewriting its history.

Verification at 4f4b89e:

• Reduced eight PR-added mirrored helper cases to three address-bar behavior cases (query, path, fragment); 19 baseline cases unchanged. Total: 27 → 22.
• With main's implementation: 3 regression cases fail, 19 pass. With the fix: all 22 pass.
• node_modules/.bin/vp test run packages/shared/src/preview.test.ts: passed.
• Targeted lint, formatting, shared package typecheck, and git diff --check: passed (existing Effect suggestions elsewhere).
• One full-diff adversarial review round, independently by Claude Opus 5.5 and Codex GPT-6 Sol: no findings.
• Actual isolated T3 web app on headless Linux, 1280×800: entering localhost:9471/redirect.html?next=https://example.com reproduces a search with the actual main helper and opens the local page with the head helper. Same fixture and viewport. A temporary downloaded fallback font supplied the host's missing fonts; no product styling changes were committed.

Before — main searches for the address:

After — head opens the local page and preserves its query:

Not verified: macOS, Windows, native iOS/Android, or Electron desktop. The shared helper callers were inspected across web, mobile, server, and desktop. This is a URL behavior fix with no visual design change.

Original work by @maxwellyoung. Takeover tests: GPT-6 Astra (high); implementation: GPT-6.1 Sol (high); reviews: Claude Opus 5.5 and GPT-6 Sol. Harnesses: Codex and Claude Code through T3 Code.

[macroscopeapp]

Approvability

Verdict: Approved at 4f4b89e

Macroscope's review found this PR approvable — This is a narrowly scoped URL parsing bug fix that preserves existing URL handling while correctly opening addresses containing embedded URLs instead of searching. The shared helper change is covered by focused regression tests and introduces no schema, deployment, security, billing, or static-analysis configuration risk.

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[coderabbitai]

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• Run ID: 89e57d8b-afd9-4fda-837e-eea847d8a3a4

📥 Commits

Reviewing files that changed from the base of the PR and between 8acaa44 and 4f4b89e.

📒 Files selected for processing: 2

• packages/shared/src/preview.test.ts
• packages/shared/src/preview.ts

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📝 Walkthrough

Preview URL handling now uses a shared pattern to identify inputs that begin with a valid scheme and authority. Address-bar tests cover inputs with embedded URLs in a query, fragment, or path.

Changes: Preview URL qualification

Layer / File(s)	Summary
URL qualification and embedded-URL handling packages/shared/src/preview.ts, packages/shared/src/preview.test.ts	A shared pattern identifies inputs that begin with a valid scheme and ://. resolveAddressBarInput uses this pattern. normalizePreviewUrl uses it to select the explicit URL path. Tests check that inputs with embedded URLs resolve to the outer address.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 4f4b8

The resolver preserves explicit URLs and correctly handles host addresses containing nested URLs. No actionable merge-blocking issue was found in the reviewed change.

Pre-merge checks: 4

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the primary fix: preview addresses containing another URL open instead of being searched.
Description check		The description covers the problem, implementation, focused verification, observed results, screenshots, and unverified platforms. It references the related PR for scope, although it does not explicit…

Full details: Description check

Explanation

The description covers the problem, implementation, focused verification, observed results, screenshots, and unverified platforms. It references the related PR for scope, although it does not explicitly identify a maintainer approval comment or explain the small-fix exemption.

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Dismissing prior approval to re-evaluate 8acaa44

[juliusmarminge]

Taking over this one. I'll resolve the conflict with main, rebuild it to repo conventions and push to this branch.

Dismissing prior approval to re-evaluate 4f4b89e