The 12-word BIP-39 test phrase survived in every release bundle as dead text: module.exports keeps DEBUG_MNEMONIC live even though wallet.js's only use of it folds away in a release build, so it could not be tree-shaken. Putting the value itself behind the __BUILD_DEBUG__ define makes esbuild fold it to null, so no distributed bundle carries it. script/verify-build now fails a release build if the phrase appears in any emitted file, so the fold cannot silently regress; test-verify-build covers both the release failure and the debug allowance. tests/extensionId.test.js now scans the content of every tracked file for a PEM private-key header instead of matching filename extensions alone, so a key committed under an unexpected name is caught. Model: opus-4-8