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>
Encrypted slots in BlobHeader:
- Private posts get noise-prefilled receipt slots (64B, 1 per participant)
and comment slots (256B, ceil(participants/3), expandable)
- Slot key derived from post CEK via BLAKE3 — only participants can read
- CDN relays propagate opaque encrypted bytes without decryption
- 3 new BlobHeaderDiffOps: WriteReceiptSlot, WriteCommentSlot, AddCommentSlots
Receipt system:
- States: empty(0), delivered(1), seen(2), reacted(3)
- Slot index = position in sorted participant NodeId list
- Author can pre-feed emoji reaction at creation time
- 6 new crypto tests for slot encrypt/decrypt/derivation
Node methods:
- write_receipt_slot, write_comment_slot with upstream+downstream propagation
- read_receipt_slots, read_comment_slots with CEK-based decryption
- get_post_cek_and_participants helper for both Encrypted and GroupEncrypted
IPC: write_message_receipt, write_message_comment, get_message_receipts,
get_message_comments
Frontend:
- DM chat bubbles show delivery indicators (check → double → blue → emoji)
- Opening conversation auto-marks incoming messages as seen
- React button on messages with emoji prompt
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
