docs(nests): record that mitigations 3+4 were net-negative

The 600 ms speaker warmup and 250 ms hang-listen post-announced()
sleep were intended to give the relay more time to prime its
per-broadcast subscribe-pump. Sweep showed they actually made
things WORSE — combined 0/5 pass (down from 2/5 with the
single-subscribe fix alone) — because the cumulative ~850 ms
of pre-subscribe delay shrank the catalog-read window into the
speaker's tear-down region.

Lesson recorded: any mitigation that adds pre-subscribe delay
hurts more than it helps. Future attempts should target the
relay's subscribe-routing race directly (upstream fix, RUST_LOG
trace, or version bump) rather than smoothing it over with
delays.

nestsClient/plans/2026-05-07-late-join-catalog-flake-investigation.md

@@ -155,16 +155,25 @@ SUBSCRIBE arriving normally.
    replaces the create-drop-recreate retry shape with one
    subscribe held for the full 10 s read budget. Eliminates the
    moq-rs `Error::Cancel` cascade. **5/5 fail → ~2-3/5 pass.**
-3. **Speaker warmup bump 150 ms → 600 ms** (`00f6cba31`) — gives
+3. **Speaker warmup bump 150 ms → 600 ms** (`00f6cba31`) — gave
    the relay more time to register the speaker's broadcast in
-   its origin before the listener subscribes. **No measurable
-   improvement** — the failing test still shows the speaker
-   receives ANNOUNCE Please/Active but no SUBSCRIBE inbound.
+   its origin before the listener subscribed. **NET NEGATIVE,
+   reverted in `1ddf4967c`** — same failure pattern AND ate
+   into the listener's catalog-read window (5 s broadcast minus
+   600 ms warmup leaves ~4.4 s instead of 4.85 s).
 4. **hang-listen 250 ms post-`origin.announced()` sleep**
-   (`207057374`) — gives the relay time to fully prime its
-   per-broadcast upstream-subscribe pump after the broadcast
-   appears in its origin map but before the listener subscribes.
-   **No measurable improvement** — same failure mode persists.
+   (`207057374`) — gave the relay time to fully prime its
+   per-broadcast upstream-subscribe pump. **NET NEGATIVE,
+   reverted in `9b8b5692b`** — combined with #3 produced 0/5
+   sweep pass (worse than single-subscribe-fix-alone's 2/5)
+   because the cumulative ~850 ms of pre-subscribe delay
+   shrank the catalog-read window into the speaker tear-down
+   region.
+
+Lesson: the failure window for the broken-routing case is
+~3 seconds (until the speaker tears down at end of broadcast).
+ANY pre-subscribe delay shrinks the available retry budget on
+the listener side. Mitigations should NOT add delays.
 
 ## Smoking gun (from speaker stderr trace)