feat(gateway): expose Kanban wake metadata

[rmacbot]

Summary

• identify each direct, user-visible Kanban terminal notification with a versioned hermes_kanban_notification envelope
• preserve existing subscription chat/thread routing metadata while keeping the stored subscription mapping unchanged
• retain the distinct hermes_kanban_wake envelope on the later synthetic internal wake, including deterministic aggregate event ordering
• preserve localized text, retry/cursor behavior, artifact delivery, ordinary sends, and the stateless API self-post shape

Delivery-plane contracts

Direct push notifications receive metadata["hermes_kanban_notification"] version 1 with only:

• board
• task_id
• the direct notification's event_kind
• the claimed batch cursor

The later push-capable synthetic MessageEvent receives event.metadata["hermes_kanban_wake"] version 1 with only:

• board
• task_id
• deterministically ordered aggregate event_kinds
• the same claimed batch cursor

The names are intentionally distinct: one direct notification represents one event, while one internal wake can aggregate several events from the claimed batch.

Compatibility and privacy

Existing subscription routing metadata remains alongside the direct-notification envelope and is copied before augmentation. Neither the caller mapping nor the stored subscription metadata is mutated. Calling deliver_wake without metadata still produces the existing internal text MessageEvent with an empty metadata mapping; supplied wake metadata is deep-copied.

Both Kanban envelopes are explicit privacy allowlists. They exclude task content, summaries/results/reasons, arbitrary event payloads, profile/assignee identity, local paths, credentials, secret-like fields, and subscription delivery metadata. Localized visible text and ordinary adapter sends are unchanged.

Stateless API self-post wakes retain their existing request shape and receive neither adapter-only envelope. Non-push delivery still relies on the existing self-post path.

Overlap reconciliation

A current open-PR scan before repair found adjacent Kanban notifier, routing, and wake work, but no open PR providing both direct per-event notification identity and the separate aggregate synthetic-wake contract. This PR remains the single candidate lineage.

Verification

• scripts/run_tests.sh tests/gateway/test_kanban_notifier.py tests/gateway/test_kanban_notifier_apiserver_wake.py tests/gateway/test_kanban_notifier_watcher_dispatch_gate.py tests/gateway/test_kanban_notifier_zero_sub_gate.py tests/gateway/test_kanban_watchers_mixin.py tests/gateway/test_wake_delivery.py tests/hermes_cli/test_kanban_notify.py tests/tui_gateway/test_kanban_notify_poller.py -q — 42 passed
• ruff check gateway/kanban_watchers.py gateway/wake.py tests/gateway/test_kanban_notifier.py tests/gateway/test_wake_delivery.py — passed
• python -m py_compile gateway/kanban_watchers.py gateway/wake.py tests/gateway/test_kanban_notifier.py tests/gateway/test_wake_delivery.py — passed
• git diff --check — passed

Residual risk

Push notification text remains the delivery boundary before the best-effort synthetic wake, matching existing behavior. The shared claimed cursor identifies retries and aggregate batches; it is not a per-event database ID.