## Problem
After the initial submit hardening, two issues remained: source code was
read in Lua and piped as stdin to the scraper (unnecessary roundtrip
since
the file exists on disk), and CF's `page.fill()` timed out on the hidden
`textarea[name="source"]` because CodeMirror owns the editor state.
## Solution
Pass the source file path as a CLI arg instead — AtCoder calls
`page.set_input_files(file_path)` directly, CF reads it with
`Path(file_path).read_text()`. Fix CF source injection via
`page.evaluate()`
into the CodeMirror instance. Extract `BROWSER_SUBMIT_NAV_TIMEOUT` as a
per-platform `defaultdict` (CF defaults to 2× nav timeout). Save the
buffer
with `vim.cmd.update()` before submitting.
Problem: with debug = true, there is not enough diagnostic output to
troubleshoot environment or execution issues. The resolved python path,
scraper commands, and compile/run shell commands are not logged.
Solution: add logger.log calls at key decision points: python env
resolution (nix vs uv vs discovery), uv sync stderr output, scraper
subprocess commands, and compile/run shell strings. All gated behind
the existing debug flag so they only appear when debug = true.
