[Bug]: Settings → Providers: editing "Health check interval" blanks and reloads the panel #21741

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

Area: apps/web
Impact: Minor bug or occasional failure

Steps to reproduce

1. Open Settings → Providers (scope: All projects, local desktop host).
2. Scroll to Advanced → Health check interval (default 300).
3. Click + or −, OR click into the field and type a new value.

Expected behavior

The value changes (or to the typed value) and persists. The panel stays mounted.

Actual behavior

The Providers panel goes blank, hangs briefly, then reloads reverting back to the default 300 value,
so the setting can't be edited from the UI at all.

Version or commit

Environment

Windows desktop app (host: local desktop). Providers: Claude v2.1.303 enabled (Claude Team subscription), Codex disabled.

Logs or stack traces

Notes from reading the code (HEAD 5307c23)

• ProviderSettingsPanel.tsx: the NumberField onValueChange calls updateSettings(...) directly on every
  change. There's no debounce or commit-on-blur, so typing fires a settings write per keystroke.
• Each write goes through backgroundActivityOverrideSettings(), which flips the profile to "custom"
  and persists all background-activity overrides at once. I suspect this triggers a settings reload or
  provider re-probe that remounts the panel mid-edit, but I haven't verified it.
• Input handling itself looks fine: normalizeIntervalSeconds() guards null and NaN.

Workaround

None found from the UI.

Expected behavior

The health check interval should change accordingly.

Actual behavior

No value is ever accepted aside from the default 300. As soon as you attempt to modify it - the page visually renders to black and resets.

Impact

Minor bug or occasional failure

Version or commit

(HEAD 5307c23)

Environment

No response

Logs or stack traces

Screenshots, recordings, or supporting files

No response

Workaround

None