## Problem
When editing trader configuration, if `system_prompt_template` was set to an empty string (""), the UI would incorrectly treat it as falsy and overwrite it with 'default', losing the user's selection.
**Root cause:**
```tsx
if (traderData && !traderData.system_prompt_template) {
// ❌ This triggers for both undefined AND empty string ""
setFormData({ system_prompt_template: 'default' });
}
```
JavaScript falsy values that trigger `!` operator:
- `undefined` ✅ Should trigger default
- `null` ✅ Should trigger default
- `""` ❌ Should NOT trigger (user explicitly chose empty)
- `false`, `0`, `NaN` (less relevant here)
## Solution
Change condition to explicitly check for `undefined`:
```tsx
if (traderData && traderData.system_prompt_template === undefined) {
// ✅ Only triggers for truly missing field
setFormData({ system_prompt_template: 'default' });
}
```
## Impact
- ✅ Empty string selections are preserved
- ✅ Legacy data (undefined) still gets default value
- ✅ User's explicit choices are respected
- ✅ No breaking changes to existing functionality
## Testing
- ✅ Code compiles
- ⚠️ Requires manual UI testing:
- [ ] Edit trader with empty system_prompt_template
- [ ] Verify it doesn't reset to 'default'
- [ ] Create new trader → should default to 'default'
- [ ] Edit old trader (undefined field) → should default to 'default'
## Code Changes
```
web/src/components/TraderConfigModal.tsx:
- Line 99: Changed !traderData.system_prompt_template → === undefined
```
- Add aiScanInterval and scanIntervalRecommend translation keys to translations.ts
- Update TraderConfigModal to use internationalized text instead of hardcoded Chinese
- Support language switching for scan interval labels and recommendations
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: tinkle-community <tinklefund@gmail.com>
