CB-WP-0035: a session that answers nothing

Two reports, one cause: the script's fetch had no .catch. When the server
had exited the promise rejected, the chain never ran, and not even the
status line moved — so a dead server and a click that did nothing were
indistinguishable. play again read as a dead button, and the linger
timeout was invisible.

Now a rejection says the session is gone and seals the page, and a
5-second heartbeat against a new /alive notices it without needing a
click, which is what the timeout case requires. The beat carries the
token, and does not extend the linger: that deadline is absolute.

The harness had the same hole. jsrun's fetch stub had no .catch, so the
branch that notices a dead server would have been unreachable in every
test — the very defect the stub's own comment records from CB-WP-0024.
Teaching it __failing, .catch and a recorded setInterval was the fix;
writing the script defensively would have repeated the trap.

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

workplans/CB-WP-0034-who-you-are-bonding-with.md

@@ -3,6 +3,7 @@ id: CB-WP-0034
 kind: product
 title: "Who you are bonding with"
 status: done
+state_hub_workstream_id: "bde0c1d5-a76c-4431-a48a-a9fa81f4d0cc"
 ---
 
 # Purpose
@@ -52,6 +53,7 @@ neighbours as they were.
 id: CB-WP-0034-T01
 status: done
 priority: high
+state_hub_task_id: "d8429ce2-991a-45df-9fcd-6b70b0e81511"
 ```
 
 **Controls:**