Cross-session message delivery stopped surfacing in the recipient session — regression in claude-desktop ≥ 1.46388.2

**Summary**

In the desktop app, sending a message from one Claude Code session to another (the "send to another session" / cross-session messaging feature) stopped being delivered to the recipient as a live turn. The sender's call is accepted, but the message never surfaces or gets processed in the target session.

**Environment**

- claude-desktop on Linux (Debian/Ubuntu, amd64)
- Affected: 1.46388.2 and 2.110.0. Last known-good: 1.24012.0.

**Regression window**

Worked fine on 1.24012.0 for weeks. The app auto-upgraded 1.24012.0 → 1.46388.2 (~2026-09-08, per apt/dpkg history) and the feature broke immediately after. Still broken after a later update to 2.110.0.

**Symptom by version**

- **1.46388.2:** the message never appears in the recipient at all — no error, nothing surfaces.
- **2.110.0:** the injected message *does* trigger a turn in the recipient ("waiting for claude…") but it aborts before producing anything; the recipient still never processes the message. The sender's delivery status returns `undelivered (no sign of starting within 20s)` or `queued`, but it never lands.

**Ruled out**

- Forward-updating to the latest (2.110.0) — did not fix it.
- A clean `apt purge` + reinstall of 2.110.0 — did not fix it (rules out a corrupted install).

**Fix / workaround**

Downgrading to 1.24012.0 restored it completely — verified with a full round-trip (a message sent to another session surfaces there as a live turn and the recipient replies). Because reverting the **code** alone fixed it, this is a code regression in the 1.46388.2 → 2.110.0 line, not local config/state.

```
sudo apt-get install claude-desktop=1.24012.0 && sudo apt-mark hold claude-desktop
```

Until it's fixed upstream, the stopgap without downgrading is for the recipient session to manually read the sender's transcript.

**Impact**

Multi-session workflows where sessions message each other are broken on every version ≥ 1.46388.2.

**Repro**

1. Open two Claude Code sessions in the desktop app.
2. From session A, send a message to session B.
3. On ≥ 1.46388.2, B never surfaces it as a live turn (1.46388.2: nothing; 2.110.0: a turn starts then aborts). On 1.24012.0 the same steps deliver normally.

Reproduce the cross-session delivery flow with two Claude Code sessions on 1.24012.0 and an affected version, using the version details and steps in this report as the baseline. Trace the sender's delivery status and the recipient's turn startup; done means a message sent from session A surfaces as a live, processed turn in session B on current versions.

Written by the indexing model from the issue text.