Marketplace: ALTCHA, rate limits, one-click report and admin blocklist #921

Parent

#913 · #18

What to build

URL paste and reporting are protected without relying on services that are unreliable in mainland China. Both require a solved ALTCHA (self-hosted proof-of-work) challenge, solved in the Client and forwarded through the Host, with escalating cost tiers (default, elevated, high) driven by recent volume per source, plus per-IP and per-repository rate limits (a repository is crawled at most once per five minutes). Each entry has a one-click Report with an optional reason, needing no account and no GitHub access. Reports from a configured number of distinct hashed sources hide the entry as hidden_reported. An authenticated admin endpoint blocklists or restores entries; blocklisted repositories cannot be listed again by paste or discovery. Raw IPs are never stored.

Acceptance criteria

• Challenge endpoint issues HMAC-signed ALTCHA challenges; paste and report reject missing, invalid, expired or replayed solutions.
• Cost tier escalates with recent volume per source.
• Per-IP and per-repository limits return typed refusals.
• Report threshold of distinct hashed sources hides the entry; duplicates from one source don't count twice.
• Admin endpoint (token secret) blocklists and restores; blocklisted repositories stay unlisted through paste and discovery.
• The modal shows the challenge for paste and report and a report confirmation.
• Worker boundary tests cover verification, tiers, limits, threshold, blocklist and admin auth.

Blocked by

• Tracer: paste a GitHub repo, see it in the Marketplace modal, install it #916