diff --git a/README.md b/README.md
index e9e5454..ccf5525 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,7 @@ dw workflow:query <workflow-id> current-status --json
 dw workflow:update <workflow-id> approve --input='{"approver":"operator"}'
 dw workflow:cancel <workflow-id> --reason="Customer request"
 dw workflow:history <workflow-id> <run-id>
+dw service-call:describe <endpoint> <service> <operation> <call-id> --json
 ```
 
 ## Automation Contract
diff --git a/docs/cli-reference.md b/docs/cli-reference.md
index c8a4f18..daaa95a 100644
--- a/docs/cli-reference.md
+++ b/docs/cli-reference.md
@@ -513,6 +513,21 @@ dw workflow:history order-123 01HXYZ
 dw workflow:history order-123 01HXYZ --follow
 ```
 
+### Nexus service calls
+
+Inspect one durable call in its endpoint namespace:
+
+```bash
+dw service-call:describe <endpoint> <service> <operation> <call-id> --namespace=shared
+dw service-call:describe <endpoint> <service> <operation> <call-id> --json
+```
+
+The response preserves the original caller and target, outcome, deadline,
+attempt records, typed failure and retained payload references. The command
+does not retry or cancel the call, or fetch external objects. JSON output
+preserves the complete Server response, including the lossless Avro
+`result_envelope` and outcome metadata.
+
 ### Namespaces
 
 ```bash
diff --git a/schemas/output/manifest.json b/schemas/output/manifest.json
index 2d4423b..e3fd4fc 100644
--- a/schemas/output/manifest.json
+++ b/schemas/output/manifest.json
@@ -6,6 +6,13 @@
   "json_schema_draft": "https://json-schema.org/draft/2020-12/schema",
   "stability": "patch-stable-additive",
   "commands": {
+    "service-call:describe": {
+      "output": "--json",
+      "schema": "schemas/output/service-call.schema.json",
+      "schema_id": "https://durable-workflow.github.io/cli-json-envelopes/v3/schemas/service-call.schema.json",
+      "resolver_url": "https://durable-workflow.github.io/cli-json-envelopes/v3/schemas/service-call.schema.json",
+      "sha256": "sha256:b9058cb4e958c8717676ec68aae46f0710751711249c32249bb021cacb344f3d"
+    },
     "debug": {
       "output": "--json",
       "schema": "schemas/output/workflow-debug.schema.json",
diff --git a/schemas/output/service-call.schema.json b/schemas/output/service-call.schema.json
new file mode 100644
index 0000000..e551583
--- /dev/null
+++ b/schemas/output/service-call.schema.json
@@ -0,0 +1,25 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "$id": "https://durable-workflow.github.io/cli-json-envelopes/v3/schemas/service-call.schema.json",
+  "title": "dw service-call:describe --json",
+  "type": "object",
+  "required": ["namespace", "id", "status", "service_call_attempts", "retry_attempt_count"],
+  "properties": {
+    "namespace": {"type": "string"},
+    "id": {"type": "string"},
+    "status": {"type": "string"},
+    "caller_namespace": {"type": ["string", "null"]},
+    "caller_workflow_instance_id": {"type": ["string", "null"]},
+    "caller_workflow_run_id": {"type": ["string", "null"]},
+    "target_namespace": {"type": ["string", "null"]},
+    "linked_workflow_instance_id": {"type": ["string", "null"]},
+    "linked_workflow_run_id": {"type": ["string", "null"]},
+    "linked_workflow_update_id": {"type": ["string", "null"]},
+    "call_deadline_at": {"type": ["string", "null"]},
+    "service_call_attempts": {"type": "array", "items": {"type": "object", "additionalProperties": true}},
+    "retry_attempt_count": {"type": "integer", "minimum": 0},
+    "caller_observed_error_type": {"type": ["string", "null"]},
+    "typed_error_message": {"type": ["string", "null"]}
+  },
+  "additionalProperties": true
+}
diff --git a/src/Application.php b/src/Application.php
index 3404436..f362236 100644
--- a/src/Application.php
+++ b/src/Application.php
@@ -18,6 +18,7 @@
 use DurableWorkflow\Cli\Commands\SchemaCommand;
 use DurableWorkflow\Cli\Commands\SearchAttributeCommand;
 use DurableWorkflow\Cli\Commands\ServerCommand;
+use DurableWorkflow\Cli\Commands\ServiceCallCommand;
 use DurableWorkflow\Cli\Commands\StorageCommand;
 use DurableWorkflow\Cli\Commands\SystemCommand;
 use DurableWorkflow\Cli\Commands\TaskQueueCommand;
@@ -148,6 +149,9 @@ public function __construct(?callable $serverClientFactory = null)
             new WorkflowCommand\HistoryExportCommand(),
             new WorkflowCommand\MigrateV1Command(),
 
+            // Durable Nexus inspection
+            new ServiceCallCommand\DescribeCommand(),
+
             // Environment profiles (local config)
             new EnvCommand\ListCommand(),
             new EnvCommand\SetCommand(),
diff --git a/src/Commands/BaseCommand.php b/src/Commands/BaseCommand.php
index bc2d62b..4f4762b 100644
--- a/src/Commands/BaseCommand.php
+++ b/src/Commands/BaseCommand.php
@@ -52,6 +52,7 @@ abstract class BaseCommand extends Command
         'search-attribute:create',
         'search-attribute:delete',
         'search-attribute:list',
+        'service-call:describe',
         'storage:test',
         'system:activity-timeout-pass',
         'system:activity-timeout-status',
diff --git a/src/Commands/ServiceCallCommand/DescribeCommand.php b/src/Commands/ServiceCallCommand/DescribeCommand.php
new file mode 100644
index 0000000..b63e6d8
--- /dev/null
+++ b/src/Commands/ServiceCallCommand/DescribeCommand.php
@@ -0,0 +1,78 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DurableWorkflow\Cli\Commands\ServiceCallCommand;
+
+use DurableWorkflow\Cli\Commands\BaseCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Formatter\OutputFormatter;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class DescribeCommand extends BaseCommand
+{
+    protected function configure(): void
+    {
+        parent::configure();
+        $this->setName('service-call:describe')
+            ->setDescription('Inspect a durable Nexus service call and its original target')
+            ->setHelp(<<<'HELP'
+Read one service call in the selected endpoint namespace. The JSON response
+preserves the server's outcome, attempt records, original caller and target,
+deadlines, typed failure and retained payload references. The result remains its
+lossless Avro result_envelope. Only a GET is issued: no retry, cancellation or
+external-object fetch is requested.
+
+  <info>dw service-call:describe billing invoices create call-42 --namespace=shared</info>
+  <info>dw service-call:describe billing invoices create call-42 --json</info>
+HELP)
+            ->addArgument('endpoint', InputArgument::REQUIRED, 'Endpoint name')
+            ->addArgument('service', InputArgument::REQUIRED, 'Service name')
+            ->addArgument('operation', InputArgument::REQUIRED, 'Operation name')
+            ->addArgument('call-id', InputArgument::REQUIRED, 'Original service call ID')
+            ->addOption('json', null, InputOption::VALUE_NONE, 'Output the complete server response as JSON');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $segments = array_map(
+            static fn (string $name): string => rawurlencode((string) $input->getArgument($name)),
+            ['endpoint', 'service', 'operation', 'call-id'],
+        );
+        $result = $this->addNamespaceContext($input, $this->client($input)->get(sprintf(
+            '/service-endpoints/%s/services/%s/operations/%s/service-calls/%s',
+            ...$segments,
+        )));
+
+        if ($this->wantsJson($input)) {
+            return $this->renderJson($output, $result);
+        }
+
+        $output->writeln('<info>Nexus Service Call</info>');
+        foreach ([
+            'Namespace' => 'namespace', 'Call ID' => 'id', 'Status' => 'status',
+            'Outcome' => 'outcome', 'Deadline' => 'call_deadline_at',
+            'Caller Namespace' => 'caller_namespace', 'Caller Workflow' => 'caller_workflow_instance_id',
+            'Caller Run' => 'caller_workflow_run_id', 'Target Namespace' => 'target_namespace',
+            'Target Workflow' => 'linked_workflow_instance_id', 'Target Run' => 'linked_workflow_run_id',
+            'Target Update' => 'linked_workflow_update_id', 'Retry Attempts' => 'retry_attempt_count',
+            'Failure Type' => 'failure_type', 'Failure Message' => 'message',
+            'Caller Failure Type' => 'caller_observed_error_type',
+            'Result Envelope' => 'result_envelope', 'Output Reference' => 'output_payload_reference',
+            'Failure Reference' => 'failure_payload_reference', 'Outcome Metadata' => 'outcome_metadata',
+            'Attempts' => 'service_call_attempts',
+        ] as $label => $field) {
+            $value = $result[$field] ?? null;
+            $text = '-';
+            if (array_key_exists($field, $result)) {
+                $text = is_string($value) ? $value : json_encode($value, JSON_THROW_ON_ERROR | JSON_UNESCAPED_UNICODE);
+            }
+            $output->writeln('  '.$label.': '.OutputFormatter::escape($text));
+        }
+
+        return Command::SUCCESS;
+    }
+}
diff --git a/tests/Commands/OutputContractTest.php b/tests/Commands/OutputContractTest.php
index 36e4e65..82810a3 100644
--- a/tests/Commands/OutputContractTest.php
+++ b/tests/Commands/OutputContractTest.php
@@ -385,6 +385,7 @@ public function test_json_mode_keeps_stderr_silent_on_error(): void
      */
     public static function namespaceScopedCommandNames(): iterable
     {
+        yield 'service call describe' => ['service-call:describe'];
         yield 'activity complete' => ['activity:complete'];
         yield 'activity describe' => ['activity:describe'];
         yield 'activity fail' => ['activity:fail'];
diff --git a/tests/Commands/ServiceCallDescribeCommandTest.php b/tests/Commands/ServiceCallDescribeCommandTest.php
new file mode 100644
index 0000000..a8f3339
--- /dev/null
+++ b/tests/Commands/ServiceCallDescribeCommandTest.php
@@ -0,0 +1,106 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Commands;
+
+use DurableWorkflow\Cli\Application;
+use DurableWorkflow\Cli\Commands\ServiceCallCommand\DescribeCommand;
+use DurableWorkflow\Cli\Support\OutputSchemaRegistry;
+use DurableWorkflow\Cli\Support\ServerClient;
+use DurableWorkflow\Cli\Support\ServerHttpException;
+use Opis\JsonSchema\Validator;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Console\Tester\CommandTester;
+
+final class ServiceCallDescribeCommandTest extends TestCase
+{
+    public static function outcomes(): array
+    {
+        return [['started'], ['completed'], ['failed'], ['cancelled']];
+    }
+
+    #[DataProvider('outcomes')]
+    public function test_json_preserves_original_outcomes_and_only_reads_one_scoped_call(string $status): void
+    {
+        $response = [
+            'id' => 'call-17', 'namespace' => '017', 'status' => $status,
+            'caller_namespace' => '0', 'caller_workflow_instance_id' => 'caller', 'caller_workflow_run_id' => 'original-caller',
+            'target_namespace' => '017', 'linked_workflow_instance_id' => 'target', 'linked_workflow_run_id' => 'original-target',
+            'call_deadline_at' => '2026-10-18T03:00:00.123456Z',
+            'outcome_metadata' => ['long' => PHP_INT_MAX, 'null' => null, 'unicode' => 'λ雪'],
+            'result_envelope' => ['codec' => 'avro', 'blob' => 'AA=='],
+            'caller_observed_error_type' => 'OriginalServiceFailure', 'typed_error_message' => 'exact failure',
+            'service_call_attempts' => [['attempt' => 1, 'status' => 'failed'], ['attempt' => 2, 'status' => 'completed']],
+            'retry_attempt_count' => 2, 'output_payload_reference' => ['provider' => 'unavailable', 'key' => 'retained'],
+        ];
+        $client = new ServiceCallDescribeClient($response);
+        $command = (new Application())->find('service-call:describe');
+        self::assertInstanceOf(DescribeCommand::class, $command);
+        $command->setServerClient($client);
+        $tester = new CommandTester($command);
+
+        self::assertSame(0, $tester->execute([
+            'endpoint' => 'billing/017', 'service' => 'invoices λ', 'operation' => '0', 'call-id' => 'call-17',
+            '--namespace' => '017', '--json' => true,
+        ]));
+        self::assertSame([['/service-endpoints/billing%2F017/services/invoices%20%CE%BB/operations/0/service-calls/call-17', []]], $client->reads);
+        self::assertSame($response, json_decode($tester->getDisplay(), true, flags: JSON_THROW_ON_ERROR));
+        self::assertTrue((new Validator())->validate(
+            json_decode($tester->getDisplay(), flags: JSON_THROW_ON_ERROR),
+            json_decode(json_encode(OutputSchemaRegistry::schema('service-call:describe'), JSON_THROW_ON_ERROR), flags: JSON_THROW_ON_ERROR),
+        )->isValid());
+    }
+
+    public function test_human_output_preserves_failure_identity_zero_and_console_markup(): void
+    {
+        $command = new DescribeCommand();
+        $command->setServerClient(new ServiceCallDescribeClient([
+            'namespace' => '0', 'id' => 'original', 'status' => 'failed', 'linked_workflow_run_id' => 'target-run',
+            'failure_type' => 'OriginalFailure', 'message' => '<info>λ雪</info>',
+            'retry_attempt_count' => 0, 'service_call_attempts' => [],
+            'result_envelope' => ['codec' => 'avro', 'blob' => 'AA=='],
+            'outcome_metadata' => ['long' => PHP_INT_MAX, 'null' => null],
+        ]));
+        $tester = new CommandTester($command);
+        self::assertSame(0, $tester->execute(['endpoint' => 'e', 'service' => 's', 'operation' => 'o', 'call-id' => 'original']));
+        foreach (['Namespace: 0', 'Target Run: target-run', 'Retry Attempts: 0', 'OriginalFailure', '<info>λ雪</info>', 'Result Envelope: {"codec":"avro","blob":"AA=="}', (string) PHP_INT_MAX, '"null":null'] as $expected) {
+            self::assertStringContainsString($expected, $tester->getDisplay());
+        }
+    }
+
+    public function test_a_server_selector_refusal_is_never_rendered_as_a_success(): void
+    {
+        $client = new ServiceCallDescribeClient([]);
+        $client->failure = new ServerHttpException('service_call_not_found', 404);
+        $command = new DescribeCommand();
+        $command->setServerClient($client);
+        $tester = new CommandTester($command);
+        self::assertSame(5, $tester->execute(['endpoint' => 'e', 'service' => 's', 'operation' => 'o', 'call-id' => 'wrong', '--namespace' => '017', '--json' => true]));
+        self::assertStringContainsString('service_call_not_found', $tester->getDisplay());
+        self::assertSame('017', json_decode($tester->getDisplay(), true, flags: JSON_THROW_ON_ERROR)['namespace']);
+        self::assertCount(1, $client->reads);
+    }
+}
+
+final class ServiceCallDescribeClient extends ServerClient
+{
+    public array $reads = [];
+    public ?ServerHttpException $failure = null;
+
+    public function __construct(private readonly array $response)
+    {
+        parent::__construct('http://localhost');
+    }
+
+    public function get(string $path, array $query = []): array
+    {
+        $this->reads[] = [$path, $query];
+        if ($this->failure !== null) {
+            throw $this->failure;
+        }
+
+        return $this->response;
+    }
+}