Import Tasks: switching source blanks the list and re-flashes the loading spinner every time

[liuxiaocs7]

What happened

In Settings → Activity → Import Tasks, changing the source (Codex / Claude Code / opencode) — including switching back to a source that was already loaded — blanks the conversation list and flashes the full-width "Reading external conversations…" spinner on every switch, then re-fetches from scratch.

Expected: returning to a source (or archived/search filter) that was already loaded should show its rows immediately, without blanking the list and re-showing the spinner each time.

How to reproduce

(Requires at least two sources that have conversations on the machine, so the source switcher renders.)

1. Open Settings → Activity → Import Tasks.
2. Wait for the first source to finish loading its list.
3. Switch to another source; wait for it to load.
4. Switch back to the first source.

Observed: the list blanks and "Reading external conversations…" appears again, even though that source was loaded a moment ago. With a slow catalog read the spinner is visible for a noticeable time on every switch.

Environment

• Maka commit: 654764fb4 (origin/main)
• OS and version: macOS (Apple Silicon)
• Surface: Desktop
• Node.js version: v24.14.0

Logs, screenshots, or additional context

Root cause is in apps/desktop/src/renderer/settings/import-tasks-settings-page.tsx: loadCatalog unconditionally calls setCatalog(EMPTY_CATALOG) + setCatalogLoading(true) on every non-append load, and there is no per-selection cache — so every source/filter change fully blanks the list and re-fetches, even for a selection just viewed.

Separately (latent, not the visible symptom): the background import poll refreshLoadedCatalog shares the same requestGeneration counter that gates the catalogLoading reset, but never resets catalogLoading itself — a fragile coupling worth hardening.

[liuxiaocs7]

Claiming this. I've opened #3905 with a fix — caching the loaded catalog per (adapterId, includeArchived, search) so a revisited source/filter renders its rows instantly and refreshes in the background, instead of blanking the list and re-flashing the spinner on every switch.