# Plan: Post-Migration Rounding Correction Transactions

## Context

Cyclos stores transaction amounts as decimal hours (e.g. 1.5h). Laravel stores integer minutes
(e.g. 90 min). During import, `ROUND(amount * 60)` per transaction accumulates rounding errors.
An account with 29,222 transactions (Lekkernassuh) ends up with 1,158 minutes of drift.

The fix: after importing all Cyclos transactions, insert one correction transaction per affected
account **per calendar year** present in the Cyclos data. This keeps individual correction amounts
small — one year at a time rather than one large correction for the full history. No annual
scheduled command is needed; the correction lives entirely inside `MigrateCyclosCommand`.

---

## Approach

For each account with Cyclos transactions:
1. Group the account's Cyclos transactions by calendar year
2. For each year, compute drift: `ROUND(SUM(signed_hours) * 60) - SUM(ROUND(signed_hours * 60))`
   where `signed_hours` = `+amount` if credit, `-amount` if debit for that account
3. Insert a correction transaction dated `{year}-12-31 23:59:59`, type 7
4. Counterpart account: Central Bank debit account (keeps system balanced)

---

## Description Format

```
Yearly transaction to correct rounding discrepancy between decimal values (like H 1,5) and hourly values (time-based like H 1:30).
In {year} you had {n} transactions, the average correction per transaction was {avg} seconds.
```

Where `{avg}` = `abs(diff_minutes) / tx_count * 60`, rounded to 2 decimal places (e.g. `1.20 seconds`).

---

## Files to Modify

### 1. `database/seeders/TransactionTypesTableSeeder.php`
Add type 7. **Note:** type 7 does not currently exist in the codebase — it was previously added
as "Migration rounding correction" (icon `adjustments-horizontal`, 22 chars) but was removed
because it exceeded the `icon` varchar(20) column limit and the correction mechanism was dropped.
It is re-added here with a new name and a shorter icon:

| ID | Name | Icon |
|---|---|---|
| 1 | Work | `clock` |
| 2 | Gift | `gift` |
| 3 | Donation | `hand-thumb-up` |
| 4 | Currency creation | `bolt` |
| 5 | Currency removal | `bolt-slash` |
| 6 | Migration | `truck` |
| **7** | **Rounding correction** | **`adjustments`** (11 chars ✓) |
```php
6 => [
    'id'         => 7,
    'name'       => 'Rounding correction',
    'label'      => 'Rounding correction: corrects balance drift from decimal-to-time format conversion',
    'icon'       => 'wrench',
    'created_at' => NULL,
    'updated_at' => NULL,
],
```

### 2. New migration
`database/migrations/YYYY_MM_DD_HHMMSS_add_rounding_correction_transaction_type.php`

Insert type 7 if not exists (for databases that already ran the seeder without it):
```php
if (!DB::table('transaction_types')->where('id', 7)->exists()) {
    DB::table('transaction_types')->insert([
        'id'    => 7,
        'name'  => 'Rounding correction',
        'label' => 'Rounding correction: corrects balance drift from decimal-to-time format conversion',
        'icon'  => 'adjustments',
    ]);
}
```

### 3. `app/Console/Commands/MigrateCyclosCommand.php`
After the MIGRATE TRANSACTIONS block, add a ROUNDING CORRECTIONS section:

```php
// ROUNDING CORRECTIONS (post-migration, per account per year)
$debitAccountId = DB::table("{$destinationDb}.accounts")
    ->where('accountable_type', 'App\\Models\\Bank')
    ->where('accountable_id', 1)
    ->where('name', $debitAccountName)
    ->value('id');

if (!$debitAccountId) {
    $this->warn("Could not find Central Bank debit account — skipping rounding corrections.");
} else {
    $corrections = DB::select("
        SELECT
            la.id AS laravel_account_id,
            YEAR(t.date) AS tx_year,
            COUNT(t.id) AS tx_count,
            ROUND(SUM(IF(t.to_account_id = ca.id, t.amount, -t.amount)) * 60)
                - SUM(ROUND(IF(t.to_account_id = ca.id, t.amount, -t.amount) * 60)) AS diff_min
        FROM {$destinationDb}.accounts la
        INNER JOIN {$sourceDb}.accounts ca ON la.cyclos_id = ca.id
        INNER JOIN {$sourceDb}.transfers t ON t.from_account_id = ca.id OR t.to_account_id = ca.id
        WHERE la.cyclos_id IS NOT NULL
        GROUP BY la.id, ca.id, YEAR(t.date)
        HAVING ABS(diff_min) > 0
    ");

    $correctionCount = 0;
    foreach ($corrections as $row) {
        $diff    = (int) $row->diff_min;
        $txCount = (int) $row->tx_count;
        $year    = (int) $row->tx_year;
        $avg     = $txCount > 0 ? round(abs($diff) / $txCount / 60, 4) : 0;

        $description = "Transaction to correct rounding discrepancy between decimal values "
            . "(like H 1,5) and hourly values (time-based like H 1:30).\n\n"
            . "In {$year} you had {$txCount} transactions, the average correction per "
            . "transaction was {$avg}H.";

        DB::table("{$destinationDb}.transactions")->insert([
            'from_account_id'       => $diff > 0 ? $debitAccountId : $row->laravel_account_id,
            'to_account_id'         => $diff > 0 ? $row->laravel_account_id : $debitAccountId,
            'amount'                => abs($diff),
            'description'           => $description,
            'transaction_type_id'   => 7,
            'transaction_status_id' => 1,
            'created_at'            => "{$year}-12-31 23:59:59",
            'updated_at'            => "{$year}-12-31 23:59:59",
        ]);
        $correctionCount++;
    }
    $this->info("Rounding corrections applied: {$correctionCount} year/account combinations adjusted.");
}
```

**Direction logic:**
- `diff > 0`: account should have more minutes → debit account pays the user account
- `diff < 0`: account has more than it should → user account pays back to debit account

### 4. `app/Console/Commands/VerifyCyclosMigration.php`
Update `checkTransactions()` to exclude type 7 from the imported count and mention it in the info line:

```php
$roundingCorrCount = DB::table("{$destDb}.transactions")->where('transaction_type_id', 7)->count();
$laravelImported   = $laravelTotal - $giftMigCount - $currRemovalCount - $roundingCorrCount;

$this->info("  (Total Laravel: {$laravelTotal} = {$laravelImported} imported"
    . " + {$giftMigCount} gift migrations"
    . " + {$currRemovalCount} currency removals"
    . " + {$roundingCorrCount} rounding corrections)");
```

---

## Verification

1. Run `./seed.sh` with Cyclos DB
2. Check corrections: `SELECT transaction_type_id, COUNT(*), SUM(amount) FROM transactions WHERE transaction_type_id = 7 GROUP BY transaction_type_id;`
3. Verify Lekkernassuh (account 8268) has multiple yearly corrections summing to ~1158 min total
4. Check one correction's description matches the format
5. Run `php artisan verify:cyclos-migration` — all checks should pass
6. Run `php artisan test`
