tidaldb/.sdlc/features/m9-community-profile-sync/tasks.md

Tasks: Community Profile Sync

T1 — Add Tag::CommunityMembership = 0x0E to storage key encoding

File: tidal/src/storage/keys.rs

• Add CommunityMembership = 0x0E variant to Tag enum.
• Add 0x0E => Some(Self::CommunityMembership) arm to from_byte.
• Update all tag-listing tests.

Status: COMPLETE

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T2 — Implement CommunityMembershipIndex

File: tidal/src/entities/community.rs (new)

• add(user_id, name) — inserts into sorted Vec, deduplicates.
• get(user_id) -> Vec<String> — cloned snapshot.
• contains(user_id, name) -> bool.
• entry_count() -> usize.
• Unit tests covering all methods.

Status: COMPLETE

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T3 — Add community_membership field to TidalDb

File: tidal/src/db/mod.rs

• Add field: community_membership: Arc<CommunityMembershipIndex>.
• Wire into both constructors.

Status: COMPLETE

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T4 — Implement db/community.rs

File: tidal/src/db/community.rs (new)

• join_community(user_id, community_name) -> Result<()> — validate, persist, update index.
• get_community_memberships(user_id) -> Result<Vec<String>> — read from index.
• is_community_member(user_id, community_name) -> Result<bool> — read from index.

Status: COMPLETE

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T5 — Startup rebuild of community membership index

File: tidal/src/db/state_rebuild.rs

• rebuild_community_memberships(users_engine, index) — scans Tag::CommunityMembership keys.
• Called from open path.

Status: COMPLETE

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T6 — Signal forwarding: try_community_forwarding

File: tidal/src/db/signals.rs

• try_community_forwarding(&self, signal_type, entity_id, weight, timestamp, user_id).
• Called from signal_with_context after try_cohort_attribution.

Status: COMPLETE

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T7 — Integration tests

File: tidal/tests/m9_community_sync.rs

10 integration tests: join_and_query_membership, signal_routes_to_community_aggregate, nonmember_signal_not_forwarded, multiple_communities_independent, membership_persists_across_restart, join_idempotent, invalid_community_name_empty, invalid_community_name_too_long, forwarding_does_not_block_primary_write, community_aggregate_windowed_count.

Status: COMPLETE — all 10 pass

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T8 — Verify

cargo test --manifest-path tidal/Cargo.toml --lib → 1299 passed
cargo test --manifest-path tidal/Cargo.toml --test m9_community_sync → 10 passed
cargo clippy --lib -- -D warnings → clean
cargo fmt --check → clean

Status: COMPLETE