Fix #51: drop the unused env-var channel from PythonBridge

CLAUDE.md

@@ -50,7 +50,7 @@ Quantum (Facade)
 - **Tests use Pest PHP**, not raw PHPUnit classes. Use `it()` / `test()` with `expect()`.
 - **Python scripts** live in `bin/python/`, not `resources/`. Each script is self-contained (reads JSON stdin, writes JSON stdout).
 - **Exceptions** all extend `AetherException` with static factory methods (`::fromPythonError()`, `::forDriver()`, etc.)
-- **PythonBridge** only passes non-null env vars to preserve boto3 credential chain (IAM Roles).
+- **PythonBridge** adds no env vars of its own: the child gets Symfony Process's default inherited environment (boto3 credential chain, IAM Roles included, works as-is). Driver settings reach the scripts only through `driver_config` in the JSON payload.
 - **QPU safety:** Drivers with `synchronous_safe: false` throw on `->run()` to prevent HTTP timeouts.
 - **EntropyGenerator::integer()** uses rejection sampling on a 256-bit batch buffer — never modulo.
 

src/Bridge/PythonBridge.php

@@ -32,21 +32,23 @@ public function __construct(
     /**
      * Execute a Python script with the given payload.
      *
+     * The bridge adds no environment variables of its own: the child receives
+     * Symfony Process's default inherited environment, so boto3's credential
+     * chain (IAM roles, profiles, AWS_* variables) behaves exactly as it does
+     * for the PHP process. Driver settings travel inside the JSON payload under
+     * `driver_config`, which is the only channel the bin/python scripts read.
+     *
      * @param  array<mixed>  $payload
-     * @param  array<string, mixed>  $driverConfig
      * @return array<mixed>
      *
      * @throws PythonEnvironmentException
      * @throws QuantumExecutionException
      */
-    public function execute(string $script, array $payload, array $driverConfig = []): array
+    public function execute(string $script, array $payload): array
     {
         $scriptPath = $this->scriptsPath.DIRECTORY_SEPARATOR.$script;
 
-        $process = new Process(
-            command: [$this->pythonPath, $scriptPath],
-            env: $this->buildEnvironment($driverConfig),
-        );
+        $process = new Process([$this->pythonPath, $scriptPath]);
 
         $process->setInput(json_encode($payload, JSON_THROW_ON_ERROR));
         $process->setTimeout($this->timeout);
@@ -148,31 +150,4 @@ public function bitstringToBytes(string $bitstring): string
 
         return $bytes;
     }
-
-    /**
-     * Build the environment variable array for the child process.
-     *
-     * Only non-null values are included to preserve boto3's credential chain.
-     *
-     * @param  array<string, mixed>  $driverConfig
-     * @return array<string, string>
-     */
-    public function buildEnvironment(array $driverConfig): array
-    {
-        $map = [
-            'region' => 'AWS_DEFAULT_REGION',
-            'bucket' => 'AETHER_S3_BUCKET',
-            'device_arn' => 'AETHER_DEVICE_ARN',
-        ];
-
-        $env = [];
-
-        foreach ($map as $configKey => $envKey) {
-            if (isset($driverConfig[$configKey])) {
-                $env[$envKey] = (string) $driverConfig[$configKey];
-            }
-        }
-
-        return $env;
-    }
 }

src/Contracts/PythonExecutor.php

@@ -12,11 +12,13 @@ interface PythonExecutor
     /**
      * Execute a Python script with the given payload.
      *
+     * Driver settings are part of the payload (`driver_config`); implementations
+     * must not need a second channel for them.
+     *
      * @param  array<mixed>  $payload
-     * @param  array<string, mixed>  $driverConfig
      * @return array<mixed>
      */
-    public function execute(string $script, array $payload, array $driverConfig = []): array;
+    public function execute(string $script, array $payload): array;
 
     /**
      * Convert a binary digit string into raw bytes.

src/Drivers/AbstractQuantumDriver.php

@@ -187,7 +187,7 @@ public function executeBatch(array $circuits): BatchResult
             'circuits' => array_map(static fn (CircuitBuilder $c): array => $c->toArray(), $circuits),
         ]);
 
-        $response = $this->bridge->execute('batch.py', $payload, $this->config);
+        $response = $this->bridge->execute('batch.py', $payload);
 
         if (! array_key_exists('results', $response) || ! is_array($response['results'])) {
             throw QuantumExecutionException::malformedResponse(
@@ -273,7 +273,7 @@ protected function runCircuit(CircuitBuilder $circuit): CircuitResult
      */
     private function runDefinition(array $definition): CircuitResult
     {
-        $response = $this->bridge->execute('circuit.py', $this->payload($definition), $this->config);
+        $response = $this->bridge->execute('circuit.py', $this->payload($definition));
 
         if (! array_key_exists('counts', $response) || ! is_array($response['counts'])) {
             throw QuantumExecutionException::malformedResponse(
@@ -303,7 +303,7 @@ protected function submitTask(CircuitBuilder $circuit): string
         $this->assertConfigured();
         $this->validateCircuits([$circuit]);
 
-        $response = $this->bridge->execute('submit.py', $this->payload($circuit->toArray()), $this->config);
+        $response = $this->bridge->execute('submit.py', $this->payload($circuit->toArray()));
 
         $taskArn = $response['task_arn'] ?? null;
 
@@ -330,7 +330,7 @@ protected function pollTask(string $taskArn): TaskSnapshot
     {
         $this->assertConfigured();
 
-        $response = $this->bridge->execute('check.py', $this->payload(['task_arn' => $taskArn]), $this->config);
+        $response = $this->bridge->execute('check.py', $this->payload(['task_arn' => $taskArn]));
 
         $status = $response['status'] ?? null;
 
@@ -364,7 +364,7 @@ public function generateEntropy(int $bits): string
             'shots' => $shots,
         ]);
 
-        $response = $this->bridge->execute('entropy.py', $payload, $this->config);
+        $response = $this->bridge->execute('entropy.py', $payload);
 
         if (! array_key_exists('bits', $response) || ! is_string($response['bits'])) {
             throw QuantumExecutionException::malformedResponse(

tests/Unit/Bridge/PythonBridgeTest.php

@@ -188,71 +188,25 @@ function fakePython(string $shBody): string
 });
 
 // -------------------------------------------------------------------------
-// buildEnvironment()
+// execute() — environment
 // -------------------------------------------------------------------------
 
-it('includes only non-null values in environment', function () {
-    $bridge = new PythonBridge('python3');
-
-    $env = $bridge->buildEnvironment([
-        'region' => 'us-east-1',
-        'bucket' => null,
-        'device_arn' => 'arn:aws:braket:::device/quantum-simulator/amazon/sv1',
-    ]);
-
-    expect($env)->toHaveKey('AWS_DEFAULT_REGION');
-    expect($env['AWS_DEFAULT_REGION'])->toBe('us-east-1');
-    expect($env)->not->toHaveKey('AETHER_S3_BUCKET');
-    expect($env)->toHaveKey('AETHER_DEVICE_ARN');
-    expect($env['AETHER_DEVICE_ARN'])->toBe('arn:aws:braket:::device/quantum-simulator/amazon/sv1');
-});
-
-it('does not include AWS credentials in environment', function () {
-    $bridge = new PythonBridge('python3');
-
-    $env = $bridge->buildEnvironment([
-        'region' => 'eu-west-1',
-        'AWS_ACCESS_KEY_ID' => 'AKIAIOSFODNN7EXAMPLE',
-        'AWS_SECRET_ACCESS_KEY' => 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
-    ]);
-
-    expect($env)->not->toHaveKey('AWS_ACCESS_KEY_ID');
-    expect($env)->not->toHaveKey('AWS_SECRET_ACCESS_KEY');
-});
-
-it('returns empty array when config is empty', function () {
-    $bridge = new PythonBridge('python3');
+it('lets the child process see the parent environment', function () {
+    // Pins the guarantee execute()'s docblock makes: a variable set in the PHP
+    // process (AWS_PROFILE, AWS_*, IAM metadata hints boto3 relies on) reaches
+    // the interpreter. It asserts the observable behaviour, not how the
+    // Process is built.
+    $_ENV['AETHER_TEST_MARKER'] = 'inherited';
 
-    $env = $bridge->buildEnvironment([]);
-
-    expect($env)->toBe([]);
-});
-
-it('maps all supported keys in environment', function () {
-    $bridge = new PythonBridge('python3');
-
-    $env = $bridge->buildEnvironment([
-        'region' => 'ap-southeast-2',
-        'bucket' => 'my-braket-bucket',
-        'device_arn' => 'arn:aws:braket:::device/qpu/ionq/ionQdevice',
-    ]);
-
-    expect($env)->toBe([
-        'AWS_DEFAULT_REGION' => 'ap-southeast-2',
-        'AETHER_S3_BUCKET' => 'my-braket-bucket',
-        'AETHER_DEVICE_ARN' => 'arn:aws:braket:::device/qpu/ionq/ionQdevice',
-    ]);
-});
-
-it('omits unset keys from environment', function () {
-    $bridge = new PythonBridge('python3');
+    try {
+        $python = fakePython('printf \'{"marker":"%s"}\' "$AETHER_TEST_MARKER"');
 
-    // Only region provided — bucket and device_arn not present at all.
-    $env = $bridge->buildEnvironment(['region' => 'us-west-2']);
+        $result = (new PythonBridge($python))->execute('circuit.py', ['qubits' => 1]);
+    } finally {
+        unset($_ENV['AETHER_TEST_MARKER']);
+    }
 
-    expect($env)->toBe(['AWS_DEFAULT_REGION' => 'us-west-2']);
-    expect($env)->not->toHaveKey('AETHER_S3_BUCKET');
-    expect($env)->not->toHaveKey('AETHER_DEVICE_ARN');
+    expect($result)->toBe(['marker' => 'inherited']);
 });
 
 // -------------------------------------------------------------------------

tests/Unit/Drivers/AbstractQuantumDriverTest.php

@@ -42,8 +42,7 @@ protected function driverName(): string
         ->method('execute')
         ->with(
             'circuit.py',
-            $this->callback(fn (array $p) => $p['driver'] === 'test' && $p['driver_config'] === ['key' => 'value']),
-            ['key' => 'value']
+            $this->callback(fn (array $p) => $p['driver'] === 'test' && $p['driver_config'] === ['key' => 'value'])
         )
         ->willReturn(['counts' => ['0' => 500, '1' => 500]]);
 
@@ -74,8 +73,7 @@ protected function driverName(): string
                     && $p['qubits'] === 16
                     && $p['shots'] === 1
                     && ! array_key_exists('bits', $p);
-            }),
-            ['key' => 'value', 'entropy_qubits' => 16]
+            })
         )
         ->willReturn(['bits' => str_repeat('1', 16)]);
 
@@ -96,8 +94,7 @@ protected function driverName(): string
         ->method('execute')
         ->with(
             'entropy.py',
-            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 16),
-            ['key' => 'value', 'entropy_qubits' => 16]
+            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 16)
         )
         ->willReturn(['bits' => str_repeat('10', 128)]);
 
@@ -110,8 +107,7 @@ protected function driverName(): string
         ->method('execute')
         ->with(
             'entropy.py',
-            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 1),
-            ['key' => 'value']
+            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 1)
         )
         ->willReturn(['bits' => str_repeat('1', 16)]);
 
@@ -250,8 +246,7 @@ protected function driverName(): string
         ->method('execute')
         ->with(
             'entropy.py',
-            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 1),
-            ['entropy_qubits' => 0]
+            $this->callback(fn (array $p) => $p['qubits'] === 16 && $p['shots'] === 1)
         )
         ->willReturn(['bits' => str_repeat('1', 16)]);
 
@@ -272,8 +267,7 @@ protected function driverName(): string
         ->method('execute')
         ->with(
             'entropy.py',
-            $this->callback(fn (array $p) => $p['qubits'] === 16),
-            ['entropy_qubits' => -4]
+            $this->callback(fn (array $p) => $p['qubits'] === 16)
         )
         ->willReturn(['bits' => str_repeat('1', 16)]);
 
@@ -294,8 +288,7 @@ protected function driverName(): string
                 && $p['circuits'] === [
                     ['qubits' => 1, 'gates' => [], 'shots' => 1000],
                     ['qubits' => 2, 'gates' => [], 'shots' => 10],
-                ]),
-            ['key' => 'value']
+                ])
         )
         ->willReturn(['results' => [
             ['counts' => ['0' => 500, '1' => 500]],

tests/Unit/Drivers/AwsBraketDriverTest.php

@@ -79,7 +79,7 @@
 
     $this->bridge->expects($this->once())
         ->method('execute')
-        ->with('circuit.py', $expectedPayload, $this->config)
+        ->with('circuit.py', $expectedPayload)
         ->willReturn(['counts' => ['00' => 512, '11' => 512]]);
 
     $result = $driver->executeCircuit($circuit);
@@ -132,8 +132,7 @@
         ->method('execute')
         ->with(
             'entropy.py',
-            ['qubits' => 16, 'shots' => 1, 'driver' => 'aws', 'driver_config' => $this->config],
-            $this->config
+            ['qubits' => 16, 'shots' => 1, 'driver' => 'aws', 'driver_config' => $this->config]
         )
         ->willReturn(['bits' => '1011001110100101']);
 
@@ -265,7 +264,7 @@
 
     $this->bridge->expects($this->once())
         ->method('execute')
-        ->with('submit.py', $expectedPayload, $this->config)
+        ->with('submit.py', $expectedPayload)
         ->willReturn(['task_arn' => 'arn:aws:braket:us-east-1:123456789012:quantum-task/abc']);
 
     $taskArn = $driver->submitCircuit($circuit);
@@ -282,7 +281,7 @@
 
     $this->bridge->expects($this->once())
         ->method('execute')
-        ->with('submit.py', $this->anything(), $config)
+        ->with('submit.py', $this->anything())
         ->willReturn(['task_arn' => 'arn:aws:braket:us-east-1:123456789012:quantum-task/async']);
 
     $taskArn = $driver->submitCircuit($circuit);
@@ -356,8 +355,7 @@
         ->method('execute')
         ->with(
             'check.py',
-            ['task_arn' => 'arn:aws:braket:us-east-1:123456789012:quantum-task/abc', 'driver' => 'aws', 'driver_config' => $this->config],
-            $this->config
+            ['task_arn' => 'arn:aws:braket:us-east-1:123456789012:quantum-task/abc', 'driver' => 'aws', 'driver_config' => $this->config]
         )
         ->willReturn(['status' => 'RUNNING']);
 

tests/Unit/Drivers/LocalSimulatorDriverTest.php

@@ -85,7 +85,7 @@
 
     $this->bridge->expects($this->once())
         ->method('execute')
-        ->with('circuit.py', $expectedPayload, $this->config)
+        ->with('circuit.py', $expectedPayload)
         ->willReturn(['counts' => ['00' => 512, '11' => 512]]);
 
     $result = $this->driver->executeCircuit($circuit);
@@ -114,8 +114,7 @@
         ->method('execute')
         ->with(
             'entropy.py',
-            ['qubits' => 16, 'shots' => 1, 'driver' => 'local', 'driver_config' => $this->config],
-            $this->config
+            ['qubits' => 16, 'shots' => 1, 'driver' => 'local', 'driver_config' => $this->config]
         )
         ->willReturn(['bits' => '1011001110100101']);
 
@@ -187,7 +186,7 @@
 
     $this->bridge->expects($this->once())
         ->method('execute')
-        ->with('circuit.py', $this->anything(), $this->config)
+        ->with('circuit.py', $this->anything())
         ->willReturn(['counts' => ['0' => 100]]);
 
     $this->driver->submitCircuit($circuit);