[Deicyde]

The anonymous rate limiters key the raw CF-Connecting-IP: flag: (POST /api/flag/:slug), csp: (the CSP report sink from #79), mcp: (POST /mcp) and brainapi-ip: (the Brain REST reads). An IPv6 client usually holds a whole /64, so it can rotate addresses and get a fresh budget on every request.

What changed

• limiterIp in wiki/src/security.ts keys an IPv6 address by its /64 (2001:db8:1:2::/64, however the address is written). Everything else keys as given, as today: IPv4, the ::/64 block (loopback and the IPv4-mapped forms, so ::ffff:cb00:7107 and its neighbours don't share one bucket), and anything it can't parse.
• All four limiters use it. Each keeps its fallback for a missing header ("" for flags and the CSP sink, "unknown" for /mcp and the REST reads).
• The /brain/api and /mcp pages and docs/BRAIN-API.md say "per /64 for IPv6" next to "per IP"; neither page is render-cached. The env.ts and wrangler.jsonc comments match.

Tests

• New wiki/test/limiter-ip.test.ts: the parser (IPv4 and ::/64 addresses kept whole, four spellings of one /64, a compressed form, and a missing header and malformed input passed through), plus one request from each of two addresses in the same /64 to all four routes, asserting the eight keys the limiters receive.
• Locally, that file plus security-headers, flags, mcp and brain-api (205 tests) and tsc --noEmit pass. My local install has hono 4.12.34; CI uses the lockfile's 4.13.12.
• Mutants caught: one call site left on the raw header, no hex normalization, a loose group count, no ::/64 rule.

Notes

• Release-affecting (wiki/src, wiki/wrangler.jsonc). Merge it before release B is built to ship it in B, or after B is promoted; not in between.
• Clients behind one IPv6 /64 now share a budget, as IPv4 clients behind one NAT already do.

[Deicyde]

Merged before release B's build (merge commit d5c9c627). An independent review found no defects. limiterIp handles the IPv6 text forms CF-Connecting-IP can carry: compressed and full, leading zeros, uppercase, and :: standing for one or more groups. A second ::, nine groups, a :: standing for zero groups, stray colons, zone ids and brackets all pass through unchanged, so malformed input can never land in another client's /64. A 30-input differential check against Python's ipaddress agreed everywhere except one case: a dotted IPv4 tail outside ::/64 keys per address, which is harmless. All four IP-keyed limiters use it, every other limit() call is keyed by user id, and neither page is render-cached. Two optional follow-ups for after B is promoted: the /mcp 429 text still says "per IP", and docs/BRAIN-API.md doesn't list the REST reads' own 120/min budget.

Posted by the WikiLean PR swarm (lead).