Scrub personal data and secrets from log lines before sharing (tokens, URL secrets, emails, IPv6/IPv4, Luhn-checked card numbers)

# Scrub personal data and secrets from logs before sharing them We share service logs in public bug reports, so `redact.py` must remove personal data and secrets first. The current regexes leak a lot and also mangle harmless text. Rewrite `redact(line) -> str` in `redact.py` (Python 3 stdlib only) to follow these rules **exactly, in this order**, each rule working on the output of the previous one. `sample.log` / `sample.expected.log` show 40 lines of correct input/output. "Word character" below means `A-Z a-z 0-9 _`. 1. **JWT.** `eyJ` followed by any run of `[A-Za-z0-9_-]`, then `.`, one or more `[A-Za-z0-9_-]`, `.`, one or more `[A-Za-z0-9_-]` -> `<JWT>`. The match must not be preceded or followed by a word character or `-`. 2. **Bearer.** The word `bearer` (any case, not preceded by a word character), then one or more spaces, then a run of non-space characters (the token). Keep the word and the spaces exactly as written; replace the token with `<TOKEN>`, except a token that is exactly `<JWT>` stays `<JWT>`. 3. **Secret URL parameters.** After `?` or `&`, a parameter named (any case) `token`, `access_token`, `api_key`, `apikey`, `key`, `secret`, `password`, `pwd` or `sig`, then `=`: its value (everything up to the next `&`, `#`, whitespace, `"`, `'` or end of line) becomes `<REDACTED>`. An empty value stays empty. Names not preceded by `?`/`&` are not parameters (`key=1` in plain text stays). 4. **Email.** Local part `[A-Za-z0-9._%+-]+` (not preceded by one of those characters), `@`, then dot-separated labels of `[A-Za-z0-9-]+` with at least two labels and a final label of 2+ letters only, not followed by `[A-Za-z0-9-]` -> `<EMAIL>`. (`a@b` and `@admin` stay.) 5. **IPv6.** Take each maximal run of the characters `0-9 A-F a-f : .`. If it contains at least two `:`, is not preceded or followed by a word character, and `ipaddress.IPv6Address(run)` accepts it, replace the whole run with `<IPV6>` (so `::ffff:1.2.3.4` is one `<IPV6>`; brackets and `:port` around it stay). Times like `12:30:45`, MAC addresses and `std::vector` stay. 6. **IPv4.** Take each maximal run of digits and dots of the form `digits(.digits)+`. Replace it with `<IPV4>` only if it has exactly 4 parts, each 0-255 with no leading zero (`0` itself is fine), it is not preceded by a word character or `.`, not followed by a word character, and not followed by `.` + digit. `:port` after it stays. `1.2.3.4.5`, `10.0.0.256`, `01.2.3.4` stay. 7. **Payment cards.** Take each maximal run of digits where neighbouring digits are separated by nothing, one space or one hyphen (pattern `\d([ -]?\d)*`). If it is not preceded or followed by a word character, has 13-19 digits in total and the digits pass the Luhn check, replace the whole run with `<CARD>`. Otherwise leave it unchanged (do not look for shorter sub-runs). Everything else in the line is kept byte for byte. ## Scoring Hidden check groups (partial credit = fraction passed; all must pass): `jwt_bearer` (1-2), `url_params` (3), `email` (4), `ipv6` (5), `ipv4` (6), `cards_luhn` (7), `rule_order` (interactions between rules), each with exact expected lines; then on a hidden 150-line log made like `sample.log`: `generated_accuracy` (at least **97%** of lines exactly equal to the correct output), `no_leaks` (on **every** line, each placeholder type appears at least as many times as in the correct output) and `no_overredaction` (**every** line that the rules leave unchanged is returned unchanged).