# EIA Brent Price Source — Primary with FRED Fallback Implementation Plan

> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.

**Goal:** Replace FRED as the primary Brent crude data source with EIA's API, keeping FRED as a silent fallback.

**Architecture:** `fetchBrentPrices()` is split into two private methods — `fetchFromEia()` and `fetchFromFred()` — each returning a mapped `array|null`. The public method tries EIA first; on `null`, warns and tries FRED; on second `null`, logs an error and returns. The upsert call is shared and runs once.

**Tech Stack:** Laravel `Http` facade, `BrentPrice::upsert()`, `config/services.php`, Pest + `Http::fake()`

---

## Files

| Action | File |
|--------|------|
| Modify | `config/services.php` |
| Modify | `.env.example` |
| Modify | `app/Services/OilPriceService.php` |
| Modify | `tests/Unit/Services/OilPriceServiceTest.php` |

---

## Task 1: Add EIA config key

**Files:**
- Modify: `config/services.php`
- Modify: `.env.example`

- [ ] **Step 1: Add EIA service config**

In `config/services.php`, add after the `'fred'` block:

```php
'eia' => [
    'api_key' => env('EIA_API_KEY'),
],
```

- [ ] **Step 2: Add EIA key to `.env.example`**

Add after the existing `FRED_API_KEY=` line:

```
EIA_API_KEY=            # US EIA Open Data API key — register free at eia.gov/opendata
```

- [ ] **Step 3: Add your real EIA key to `.env`**

Add after `FRED_API_KEY=`:

```
EIA_API_KEY=your_key_here
```

- [ ] **Step 4: Commit**

```bash
git add config/services.php .env.example
git commit -m "config: add EIA API key for Brent crude price source"
```

---

## Task 2: Write failing tests for EIA fetch behaviour

**Files:**
- Modify: `tests/Unit/Services/OilPriceServiceTest.php`

- [ ] **Step 1: Replace the three existing FRED fetch tests with four new tests**

Replace the `// --- fetchBrentPrices ---` section (lines 22–69) with:

```php
// --- fetchBrentPrices ---

it('fetches and stores brent prices from EIA when EIA succeeds', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::response([
            'response' => [
                'data' => [
                    ['period' => '2026-04-02', 'value' => '73.80'],
                    ['period' => '2026-04-01', 'value' => '75.10'],
                    ['period' => '2026-03-31', 'value' => '74.50'],
                ],
            ],
        ]),
        '*/fred/*' => Http::response([], 500),
    ]);

    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(3)
        ->and(BrentPrice::find('2026-04-02')->price_usd)->toBe('73.80');
    Http::assertNothingSentTo('*fred*');
});

it('falls back to FRED when EIA returns a 500', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::response([], 500),
        '*/fred/series/observations*' => Http::response([
            'observations' => [
                ['date' => '2026-04-01', 'value' => '75.10'],
                ['date' => '2026-04-02', 'value' => '73.80'],
            ],
        ]),
    ]);

    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(2);
});

it('falls back to FRED when EIA returns empty data', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::response(['response' => ['data' => []]]),
        '*/fred/series/observations*' => Http::response([
            'observations' => [
                ['date' => '2026-04-01', 'value' => '75.10'],
            ],
        ]),
    ]);

    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(1);
});

it('stores no rows and logs error when both EIA and FRED fail', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::response([], 500),
        '*/fred/series/observations*' => Http::response([], 500),
    ]);

    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(0);
});

it('filters out EIA missing value markers', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::response([
            'response' => [
                'data' => [
                    ['period' => '2026-04-01', 'value' => '75.10'],
                    ['period' => '2026-04-02', 'value' => '.'],
                    ['period' => '2026-04-03', 'value' => '74.20'],
                ],
            ],
        ]),
    ]);

    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(2)
        ->and(BrentPrice::find('2026-04-02'))->toBeNull();
});

it('upserts existing brent price rows on refetch via EIA', function (): void {
    Http::fake([
        '*/eia.gov/*' => Http::sequence()
            ->push(['response' => ['data' => [['period' => '2026-04-01', 'value' => '74.00']]]])
            ->push(['response' => ['data' => [['period' => '2026-04-01', 'value' => '75.50']]]]),
    ]);

    $this->service->fetchBrentPrices();
    $this->service->fetchBrentPrices();

    expect(BrentPrice::count())->toBe(1)
        ->and(BrentPrice::find('2026-04-01')->price_usd)->toBe('75.50');
});
```

- [ ] **Step 2: Run the new tests to confirm they fail**

```bash
php artisan test --compact tests/Unit/Services/OilPriceServiceTest.php --timeout=10
```

Expected: several FAIL — "no matching fake" or assertion errors (EIA endpoint not yet implemented).

---

## Task 3: Refactor `OilPriceService::fetchBrentPrices()`

**Files:**
- Modify: `app/Services/OilPriceService.php`

- [ ] **Step 1: Replace `fetchBrentPrices()` and extract private methods**

Replace the entire `fetchBrentPrices()` method with:

```php
/**
 * Fetch the last 30 days of Brent crude prices.
 * Tries EIA first; falls back to FRED if EIA is unavailable.
 */
public function fetchBrentPrices(): void
{
    $rows = $this->fetchFromEia();

    if ($rows === null) {
        Log::warning('OilPriceService: EIA fetch failed, falling back to FRED');
        $rows = $this->fetchFromFred();
    }

    if ($rows === null) {
        Log::error('OilPriceService: both EIA and FRED fetch failed');

        return;
    }

    BrentPrice::upsert($rows, ['date'], ['price_usd']);
}

/**
 * Fetch Brent crude prices from the EIA Open Data API.
 * Returns mapped rows or null on any failure.
 *
 * @return array{date: string, price_usd: float}[]|null
 */
private function fetchFromEia(): ?array
{
    $url = 'https://api.eia.gov/v2/petroleum/pri/spt/data/';

    try {
        $response = $this->apiLogger->send('eia', 'GET', $url, fn () => Http::timeout(10)
            ->get($url, [
                'api_key' => config('services.eia.api_key'),
                'frequency' => 'daily',
                'data[0]' => 'value',
                'facets[series][]' => 'RBRTE',
                'sort[0][column]' => 'period',
                'sort[0][direction]' => 'desc',
                'length' => 30,
            ]));

        if (! $response->successful()) {
            Log::error('OilPriceService: EIA request failed', ['status' => $response->status()]);

            return null;
        }

        $rows = collect($response->json('response.data') ?? [])
            ->filter(fn (array $row) => ($row['value'] ?? '.') !== '.')
            ->map(fn (array $row) => [
                'date' => $row['period'],
                'price_usd' => (float) $row['value'],
            ])
            ->all();

        if (empty($rows)) {
            Log::warning('OilPriceService: no valid EIA observations returned');

            return null;
        }

        return $rows;
    } catch (Throwable $e) {
        Log::error('OilPriceService: fetchFromEia failed', ['error' => $e->getMessage()]);

        return null;
    }
}

/**
 * Fetch Brent crude prices from FRED (fallback).
 * Returns mapped rows or null on any failure.
 *
 * @return array{date: string, price_usd: float}[]|null
 */
private function fetchFromFred(): ?array
{
    $url = 'https://api.stlouisfed.org/fred/series/observations';

    try {
        $response = $this->apiLogger->send('fred', 'GET', $url, fn () => Http::timeout(10)
            ->get($url, [
                'series_id' => 'DCOILBRENTEU',
                'api_key' => config('services.fred.api_key'),
                'sort_order' => 'desc',
                'limit' => 30,
                'file_type' => 'json',
            ]));

        if (! $response->successful()) {
            Log::error('OilPriceService: FRED request failed', ['status' => $response->status()]);

            return null;
        }

        $rows = collect($response->json('observations') ?? [])
            ->filter(fn (array $obs) => $obs['value'] !== '.')
            ->map(fn (array $obs) => [
                'date' => $obs['date'],
                'price_usd' => (float) $obs['value'],
            ])
            ->all();

        if (empty($rows)) {
            Log::warning('OilPriceService: no valid FRED observations returned');

            return null;
        }

        return $rows;
    } catch (Throwable $e) {
        Log::error('OilPriceService: fetchFromFred failed', ['error' => $e->getMessage()]);

        return null;
    }
}
```

- [ ] **Step 2: Run Pint to fix formatting**

```bash
vendor/bin/pint app/Services/OilPriceService.php --format agent
```

- [ ] **Step 3: Run the tests**

```bash
php artisan test --compact tests/Unit/Services/OilPriceServiceTest.php --timeout=10
```

Expected: all PASS.

- [ ] **Step 4: Commit**

```bash
git add app/Services/OilPriceService.php tests/Unit/Services/OilPriceServiceTest.php
git commit -m "feat: use EIA as primary Brent crude source with FRED fallback"
```

---

## Task 4: Smoke-test the live fetch

- [ ] **Step 1: Run the command against the live APIs**

```bash
php artisan oil:predict --fetch
```

Expected output: starts with "Fetching latest Brent crude prices from FRED..." (existing message — acceptable), followed by a successful prediction line. No error output.

- [ ] **Step 2: Verify EIA data landed in the database**

```bash
php artisan tinker --execute 'echo App\Models\BrentPrice::orderBy("date","desc")->value("date");'
```

Expected: a date more recent than `2026-04-02` if EIA has newer data, otherwise `2026-04-02` (EIA and FRED may both be current to the same date — that is acceptable).