approvals: ship raw diff text instead of pre-rendered html; client classifies per-line

TODO.md

@@ -34,3 +34,4 @@
 
 - ~~**Pending message wake-up**~~ ✓ fixed (e423d57) — subscribe-before-check race in `broker.recv_blocking` meant a send landing between the initial `recv()` and `subscribe()` was missed; agent then sat on the 180s long-poll until another, unrelated message woke it. Now subscribe first.
 - **Post-rebuild system-message missed wake**: at 09:13:14 the dashboard showed `system → damocles container rebuilt` as ✓ delivered, but the agent harness never ran a turn for it (no claude invocation, no operator-visible activity). A subsequent `recv()` from inside the agent returned `(empty)`, confirming the message was popped + marked delivered server-side — yet drove no turn. Most likely cause: the agent_server `serve_agent_stdio` task is up and answering MCP/socket calls, but the `hive-ag3nt::serve` long-poll loop that drives `drive_turn` either died silently during rebuild or never restarted. Investigate: (a) does hive-ag3nt's serve loop survive `nixos-container update` cleanly, or does its tokio runtime get torn down mid-loop? (b) is there an early-exit path on a transient socket error during rebuild that drops the serve task without notifying the manager? (c) compare timeline with manager's own post-rebuild wake to see if this is rebuilt-agents-only or universal. Could be related to the `recv_blocking` fix in `e423d57` if the rebuild restarts the broker mid-subscribe.
+- **`LiveEvent::Note(String)` never reaches the browser**: the enum is `#[serde(tag = "kind", rename_all = "snake_case")]` with `Note(String)` as a newtype variant — `serde_json::to_string` errors at runtime with `cannot serialize tagged newtype variant containing a string`. The SSE handler's `filter_map(... .ok()? ...)` silently drops the event; the sqlite history persists it as the literal string `"null"`. Every `bus.emit(LiveEvent::Note(...))` call site has been a no-op since the variant was added, and the JS terminal's `note` renderer is dead code. Fix: convert to a struct variant `Note { text: String }` (matches what the JS already reads via `ev.text`) and verify the existing call sites still type-check. While there, audit the sqlite-stored `"null"` rows so history-replay doesn't trip on them.