NIP-AD web addresses for relay groups, event pages and hosted sites

[FelineStateMachine]

Motivation

A URL shared from bind.ws opens in a browser but does not tell a supporting Nostr client which local event it represents. NIP-AD gives relay homepages, event/article pages and hosted sites a Nostr counterpart.

Change

• Implements /.well-known/nostr.json?path=<original-path> from proposal 2406, pinned to b82a9bf66ec9757149b5aa3b3cd36190dd4e6fed (checked 2026-09-04).
• Maps the homepage to the exact relay-authored NIP-29 metadata address, /e/<id> to that event version, /a/... to its article address, and mapped NIP-5A site paths to their live manifest or snapshot. Every mapping has an exact filter, limit: 1, and explicit relay hints.
• Reuses browser event/path resolution and preserves private reads, moderation/deletion/expiry, disabled features, custom-domain targets, site authentication and site-origin isolation. Discovery never fetches external URLs or site file bytes.
• Preserves NIP-05 name and directory semantics; name takes precedence when both parameters are supplied. Path discovery remains independent of the names feature. GET/HEAD and narrow OPTIONS preflight use CORS and non-storable responses.
• Documents the pinned proposal, path encoding, HTTP contract and compatibility limits; extends HTTP exposure and site-cookie coverage.

Compatibility and coordination

The upstream proposal is still open. This PR does not change NIP-11 supported_nips; the parallel NIP-9a compatibility PR owns lettered advertisement. Merge this PR before that PR, which will advertise AD. This PR has no dependency on NIP-9a or NIP-86 claims. Site discovery describes manifest mappings without guaranteeing file availability; the browser site door retains its hash checks and file-fetch policy.

Testing Completed

• npm run typecheck: passes TypeScript, generated artifacts, console, celld configuration and template checks.
• npm test -- --maxWorkers=4: all 45 files / 229 tests pass on the final implementation. An earlier default-pool run passed 225 tests; the final default-pool attempt stalled without an assertion failure, so the final complete run bounds worker concurrency.
• Focused coverage includes exact filters and article replacement, private/group admission, hidden/deleted/expired events and manifests, disabled features, custom/stale-host isolation, local relay hints, encoded filenames, NIP-05 coexistence, NIP-98/site cookies, CORS and malformed requests.
• Independent subagent policy and final source reviews completed; findings were checked and resolved before submission.

Responsible AI disclosure

Implemented and reviewed with Codex and subagents. Maintainers retain final review and merge decisions; no merge or deployment was performed.