[codex] fix: preserve localhost preview hosts

[StiensWout]

Summary

• Preserve normalized localhost discovered preview URLs when the prepared connection itself is local loopback.
• Keep 0.0.0.0 flowing through the existing environment-port normalization path.
• Keep private remote host remapping for discovered loopback ports.

Root cause

resolveDiscoveredServerUrl(...) treated every loopback discovered URL as an environment-port target. When the prepared connection base was http://127.0.0.1:<port>, that remapped localhost:<port> onto 127.0.0.1:<port>, even though the normalized user-visible URL should stay on localhost.

Impact

Users opening a discovered localhost dev server from a local prepared environment keep the localhost host, which preserves host-specific API allowlists. Wildcard local hosts such as 0.0.0.0 still normalize to a concrete reachable host, and private remote environments still remap discovered loopback ports onto the private environment host.

Validation

• PATH="$HOME/.vite-plus/bin:$PATH" vp test apps/web/src/browser/browserTargetResolver.test.ts passed: 1 file passed, 7 tests passed.
• PATH="$HOME/.vite-plus/bin:$PATH" vp check passed: 0 errors; 20 existing unrelated warnings.
• PATH="$HOME/.vite-plus/bin:$PATH" vp run typecheck passed: completed successfully.

Closes #3124

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Note

Low Risk
Small, targeted change to preview URL resolution in the web app with clear tests and no auth or data-path impact.

Overview
resolveDiscoveredServerUrl no longer remaps discovered localhost URLs onto 127.0.0.1 when the prepared environment connection is itself a local loopback host (localhost, 127.0.0.1, or ::1). In that case it returns the normalized URL unchanged so host-specific API allowlists stay on localhost.

Discovered 0.0.0.0 URLs still go through environment-port normalization, and loopback discoveries against private remote prepared bases still remap ports onto the environment host as before. A new isLocalLoopbackHost helper drives the early-return branch, with a unit test covering 127.0.0.1 prepared base + localhost picker input including path, query, and hash.

^{Reviewed by Cursor Bugbot for commit e581f07. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Preserve localhost preview hosts in resolveDiscoveredServerUrl

Previously, resolveDiscoveredServerUrl would rewrite loopback URLs through environment-port resolution even when both the discovered host and the prepared connection base host were local loopbacks. This adds a new isLocalLoopbackHost helper and an early-return path in resolveDiscoveredServerUrl that returns the normalized URL unchanged when both sides are loopback (localhost/127.0.0.1/::1) and the discovered host is not 0.0.0.0. If no prepared connection exists, the function now returns the raw input instead of attempting port mapping.

^{Macroscope summarized e581f07.}

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[macroscopeapp]

Approvability

Verdict: Approved

Straightforward bug fix that preserves localhost preview URLs when the environment is also running on localhost. The change is small, self-contained, includes a test, and has clear intent with limited scope.

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