[Ddongddi]

install.ps1 encoded the elevated script twice: the script as UTF-8 base64 inside a wrapper, then the wrapper as UTF-16 base64 for -EncodedCommand. The recent installer growth pushed that to a 37,352-character command line, past Windows' 32,767-character limit. Start-Process powershell.exe -Verb RunAs ... -EncodedCommand ... then failed with "The parameter is incorrect" before the UAC prompt, so dashboard updates from 0.10.4 to 0.10.8 could not run.

Pass the elevated script directly as -EncodedCommand (UTF-16 base64, 27,640 characters) and prepend the values the param block would have taken. The direct -Elevated path is unchanged. Extend scripts/test-legacy-update.ps1 to assert the encoded command stays under the limit and that the decoded script parses.

Verified on Windows: the patched installer updated Tacit 0.10.4 (enkoja) to 0.10.8 with en/ko/ja packs; the legacy-update test passes.

[helloiamnotth3devnicetomeetyou]

Reviewed the installer path and added regression coverage before merging. The tests now measure the complete Windows command line (including the executable, arguments, and terminating NUL), exercise both editions and install/uninstall argument combinations, and verify that the elevated installer body is preserved unchanged. Bilingual changelog entries are included.

All five CI checks pass; local Windows PowerShell 5.1 installer, rollback, default-input, and changelog checks also pass. Landing as a maintainer-signed squash while preserving contributor attribution.