Security:
- Reaction signatures: ed25519 sign/verify (sign_reaction, verify_reaction_signature)
Backward-compatible — unsigned reactions from old nodes still accepted
- Comment signature verification: verify_comment_signature now called on receipt
- Reaction removal authorization: only reactor or post author can remove
- BlobHeader author verification: lookup actual author from storage, don't trust payload
Lock contention (4 fixes):
- ManifestPush discovery: cm lock released before PostFetch I/O
- Pull request handler: load under lock, filter without lock, brief re-lock for is_deleted
- Pull sender: split into two brief locks (store posts, then batch upstream+sync)
- Engagement checker: batch all chunk results, single lock for writes
Data cleanup:
- Post deletion cleans post_downstream, post_upstream, seen_engagement tables
- Added TODO-hardening.md documenting remaining DOS/security/lock/data issues
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
