Quoted proxy credentials generate invalid Chrome extension JavaScript

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Environment

- FlareSolverr version: master at 0f05ed8fc974b215c36892b5a30122e27fe3c671
- Last working FlareSolverr version: unknown
- Operating system: Windows 11 (unit-level reproducer)
- Are you using Docker: no
- FlareSolverr User-Agent (see log traces or / endpoint): not applicable
- Are you using a VPN: no
- Are you using a Proxy: yes
- URL to test this issue: any target through a proxy with quote-containing credentials

Description

Description

The proxy-extension generator interpolates the proxy URL and credentials directly into generated JavaScript. Quotes, backslashes, or newlines in proxy credentials make background.js syntactically invalid; unescaped content can also change the generated script.

Expected behaviour

Arbitrary proxy credential strings should be represented as JavaScript string values and passed unchanged to Chrome's proxy-auth callback.

Proposed fix

Build the proxy configuration and credential objects in Python and serialize them with json.dumps before embedding them in the extension. A focused regression test uses quote-containing values and verifies the generated script has valid serialized configuration.

Logged Error Messages

No server log is required; Chrome rejects the generated extension script when the injected JavaScript is invalid.

Screenshots

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