PHP truthy semantics treat the literal `'false'` as truthy, so `$value ? 'true' : 'false'` in `setVariableValue()` persisted every 'switch off' request as `'true'` for ~30 modules with bool config variables. Canonicalise via the existing `inputToBool()` helper before the ternary so JSON.stringify(boolean) inputs land on the right storage string.
Live repro (api-v2.truckwash.io, 2026-08-10 09:25):
```
POST /minimax/config {variable:"enabled", value:"false"} → 200
GET /minimax/config?variable=enabled → {value:true, ...} ← unchanged
POST /minimax/config {variable:"enabled", value:false} → 200
GET /minimax/config?variable=enabled → {value:false, ...} ← JSON bool works
```
Tests: `tests/Unit/MiniMax/MiniMaxEnabledSetVariableValueTest.php` (6 assertions, captures the UPDATE column value via stubbed `updateVariableValue`/`insertVariableValue` for string/boolean × true/false × insert/update paths).
Companion pleno-vue PR #281 lands the matching UI-side fix (`onMiniMaxEnabledSwitch` re-fetches + optimistic rollback).
Regression coverage for the read-side shape that the frontend `ConfigurationXLVask.refreshMiniMaxApiKeyStatus` parses. Mirrors `BirdConfigSecretRedactionTest` — locks the contract that `api_key` is redacted with `isSet` reflecting actual persistence, so the XL Vask autopilot's `requireModuleEnabled` cannot silently break on a regression.
No production-code change — backend already correct (verified live 2026-08-10 07:58 against `api-v2.truckwash.io` with both `{variable, value}` and raw-key payload shapes).
Companion pleno-vue PR: #281 ("fix(pleno-vue): persist MiniMax API key across refresh + render fix").
Jeppe B