Adds the on-wire shapes for FoF Mode 2 comment-gating per
docs/fof-spec/layer-2-mode2-fof-comments.md:
- WrapSlot: per-V_x slot with 2B prefilter_tag + 48B read_ciphertext
+ 48B sign_ciphertext (sealed CEK + sealed priv_x_seed). 98 bytes
total per slot. Receiver trial-decrypts via prefilter match.
- FoFCommentGating: author-published gating block embedded in
Post.fof_gating. Carries slot_binder_nonce (32B random; replaces
spec's circular "post_id in HKDF info"), pub_post_set (1:1 with
wrap_slots, includes dummy pubkeys), wrap_slots, and revocation_list
(initially empty; revocation diffs accumulate on the BlobHeader copy).
- RevocationEntry: author-signed entry triggering retroactive comment
delete + pub_post_set removal on every file-holder that receives it.
- CommentPermission gains FriendsOfFriends variant. Existing match arm
in connection.rs handle-incoming-diff path is extended with a
"drop pending CDN four-check verification" stub (full verify in a
later slice).
- InlineComment extended with three optional fields:
pub_x_index: index into parent post's pub_post_set
group_sig: 64B ed25519 sig under priv_x
encrypted_payload: ChaCha20-Poly1305 ciphertext under CEK_comments
All #[serde(default)] for back-compat. Old comments deserialize
cleanly with None.
- Post gains optional fof_gating field for the author-signed snapshot
at publish time. PostId = BLAKE3(Post) covers it, so any tampering
is detectable. Mutations (revocation, access-grant) arrive later as
diffs against the local BlobHeader copy.
All 21 existing Post construction sites + 4 existing InlineComment
sites updated via perl -0pe sweeps to pass None for the new fields.
Full test suite: 134/134 pass (4 new slot crypto + 130 existing).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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