[BUG] Epitaxy (Windows desktop): microphone device selector forgets its choice and reverts to the system default input device -- no way to pin dictation to a non-default mic

Summary

In the Windows desktop app, the dictation microphone selector does not hold the device I pick. It intermittently reverts to the Windows default input device, sometimes several times within a single session. There is no way to pin dictation to a specific, non-default mic and have it stay pinned.

Why this matters (real-world setup)

My Windows default communications device is a Plantronics headset sitting in a cradle about ten feet away. It can pick me up, but only just. For dictation I use a lapel mic clipped to my collar, which is why I select it explicitly in Epitaxy rather than relying on the system default.

When the selector silently drops back to the default, dictation starts listening through the distant cradle headset instead of the lapel mic, and recognition accuracy falls off a cliff. The failure is silent, so I often don't notice for a while -- I just see garbage transcription and have to work out that the input device changed underneath me.

Steps to reproduce

1. Have a non-default audio input device available (in my case a lapel mic; the Windows default input/communications device is a different mic).
2. In Epitaxy, select the non-default mic in the dictation device selector.
3. Use the app normally -- in particular, switch between sessions in the left-hand sidebar a few times.
4. Check which input device dictation is actually using.

Note: this may be hard to reproduce on a typical machine. As an audio developer I have 18 active capture/input endpoints on this box (28 audio endpoints total), so there is a lot of opportunity for an enumeration or default-fallback path to pick the "wrong" device. I don't think it needs a clean repro to fix -- a read through the selector's persistence and re-apply logic should make the cause obvious.

Expected

The selected mic stays selected for dictation until I deliberately change it, and the choice persists across session switches and across full app restarts.

Actual

The selection reverts to the system default input device on its own. It is intermittent rather than consistent:

• I have seen it revert multiple times within one session.
• It seems to revert most reliably when I switch sessions in the left-hand sidebar.
• At other times it holds the chosen device for a while (it is holding right now).
• I strongly suspect a fresh restart of Epitaxy comes up on the default device again rather than restoring my last choice, i.e. the choice is not reliably persisted.

Suspected mechanism (hunch, not verified)

It feels like more than one part of the harness writes the same shared device setting, and they clobber each other. That would explain why it is intermittent and why a session switch in the sidebar is a frequent trigger: one code path re-initializes audio with the system default and overwrites the value a different code path had set from my explicit choice. Worth checking whether the selected-input-device setting has a single writer, or several that don't all honor the persisted user choice.

Environment

• Claude for Windows (Epitaxy desktop app), Version 1.13576.0 (1290fc)
• Windows 11
• 18 active audio input/capture endpoints, 28 audio endpoints total