Task 12 — NotificationGate implementation
Date: 2026-09-01

What was built:
- crates/news-server/src/gate.rs
  - NotificationGate, TokenBucket, NotifyConfig
  - GateDecision / SuppressReason enums
  - evaluate() with refill → already-notified → bypass → normal → bucket logic
- crates/news-server/src/lib.rs: pub mod gate + re-exports
- crates/news-server/src/error.rs: ServerError::DateTime(String) variant
- root Cargo.toml [workspace.dependencies]: chrono-tz = "0.10"
- crates/news-server/Cargo.toml: chrono-tz = { workspace = true }

Verification commands:

--- cargo fmt --all --check ---
(no output, exit 0)

--- cargo clippy --workspace --all-targets -- -D warnings ---
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.30s
(exit 0)

--- cargo test -p news-server ---
running 11 tests
test gate::tests::material_update_notifies_again_when_delta_reached ... ok
test gate::tests::bypass_ceiling_is_independent_of_normal_budget ... ok
test gate::tests::happy_path_notifies_when_relevance_and_budget_allow ... ok
test scoring::trained_model_persists_and_reloads_with_same_total_samples ... ok
test gate::tests::below_band_suppresses_below_threshold ... ok
test gate::tests::already_notified_suppresses_when_delta_not_reached ... ok
test scoring::matching_item_scores_higher_than_non_matching ... ok
test gate::tests::digest_band_returns_digest ... ok
test gate::tests::quiet_hours_suppresses_high_relevance ... ok
test scoring::importance_scorer_matches_direct_formula ... ok
test scoring::blocklist_veto_returns_neg_infinity ... ok

test result: ok. 11 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s

Gate test names:
- gate::tests::happy_path_notifies_when_relevance_and_budget_allow
- gate::tests::digest_band_returns_digest
- gate::tests::below_band_suppresses_below_threshold
- gate::tests::material_update_notifies_again_when_delta_reached
- gate::tests::already_notified_suppresses_when_delta_not_reached
- gate::tests::quiet_hours_suppresses_high_relevance
- gate::tests::bypass_ceiling_is_independent_of_normal_budget