an answer that goes nowhere now says so, and one that lands says that too

Second half of the AskUserQuestion report: "when I answer, the agent does not react — I see the bubble
for a long time and end up sending a message anyway", intermittently and not reproducible.

Two different causes, both invisible from the outside.

A DROPPED answer was silent at every step. user-instance discarded the boolean, sendFire does nothing
when no sidecar is connected, and the lookup returns undefined for both "no such session" and "not
yours". So a lost answer and a slow agent looked identical: a card that does not change. It now warns
with the reason, and where a session exists it emits an error into the durable log — the same channel a
successful answer uses, so a second pane sees it too, rather than confirming to the browser that
clicked.

A LANDED answer had the opposite problem. The card goes read-only the moment you pick, but `sent` is
local and optimistic while `message.output` only arrives once the harness has produced something. In
between there is a real gap, and nothing filled it — so an answered card looked exactly like one that
had timed out. It now says "Answer sent — waiting for the agent", which makes the two states different
without pretending to know when the agent will speak.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/sidecar/claude/user-instance.ts

@@ -321,6 +321,8 @@ async function handleCommand(cmd: SidecarCommand, reply: ReplyFn) {
     // the plan commands above, one layer deeper: what the user needs to see is the question's own card
     // filling in, and that arrives as the `tool:result` this unblocks.
     case 'claude:question-answer':
+      // The boolean was discarded here, which is how a dropped answer became invisible. It reports its
+      // own reason now — this only has to stop throwing it away.
       claudeManager.answerClaudeQuestion(cmd.sessionKey, cmd.userId, cmd.toolCallId, cmd.answer);
       break;