diff --git a/src/Cli/WorkflowMode.php b/src/Cli/WorkflowMode.php
index c4bb0e2..a5aa20d 100644
--- a/src/Cli/WorkflowMode.php
+++ b/src/Cli/WorkflowMode.php
@@ -13,10 +13,9 @@
 use Claw\Project\IssueStatus;
 use Claw\Project\ProjectStore;
 use Claw\Project\Strategy;
-use Claw\Run\ConsoleRunFrontend;
-use Claw\Run\IssueRunner;
 use Claw\Run\Triage;
 use Claw\Server;
+use Claw\ServerClient;
 use Claw\ServerLocator;
 use Claw\Trace\Level;
 use Claw\Trace\TraceReader;
@@ -253,23 +252,33 @@ private function runIssue(array $args, ?string $projectDir, ?Level $verbosity):
         try {
             $store = $this->resolve($projectDir);
             $issue = $store->loadIssue($issueId);
-            $config = Config::load($this->root . '/.env');
         } catch (ClawException $e) {
             fwrite(STDERR, 'claw run: ' . $e->getMessage() . "\n");
 
             return 1;
         }
 
-        $agent = AgentFactory::make($config, new CurlHttpClient());
+        // The CLI is a thin client: the server is the one process that writes a project db, so hand the
+        // run to it rather than opening the db here. If none is running, start one and wait for it.
+        $client = new ServerClient(new CurlHttpClient(), $this->appHome(), $this->root);
+
+        try {
+            if ($client->running() === null) {
+                fwrite(STDOUT, "claw run: no server running for this workspace — starting one…\n");
+            }
 
-        if ($agent === null) {
-            fwrite(STDERR, "claw run: agent '{$config->agent}' is not wired yet.\n");
+            $server = $client->ensure();
+            $client->startRun($server, $store->project()->id, $issue->id);
+        } catch (ClawException $e) {
+            fwrite(STDERR, 'claw run: ' . $e->getMessage() . "\n");
 
             return 1;
         }
 
-        return new IssueRunner($this->projectsDir(), $store, $config, $agent, new ConsoleRunFrontend($verbosity))
-            ->run($issue);
+        fwrite(STDOUT, "Run started for issue #{$issue->id} on the server at {$server['host']}:{$server['port']}.\n");
+        fwrite(STDOUT, "  watch it:  claw log\n");
+
+        return 0;
     }
 
     /**
diff --git a/src/ServerClient.php b/src/ServerClient.php
new file mode 100644
index 0000000..4b93f96
--- /dev/null
+++ b/src/ServerClient.php
@@ -0,0 +1,196 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Claw;
+
+use Claw\Exceptions\ClawException;
+use Claw\Http\HttpClientInterface;
+
+/**
+ * The CLI's side of the one-writer rule: it does not open a project db, it asks the server to. The
+ * server is the only process that writes, so the CLI finds one ({@see ServerLocator}) and, when there
+ * is none, starts one and waits for it to answer — then it is a thin client, a manager that hands work
+ * off rather than doing it.
+ *
+ * Autospawn needs to launch php WITH the server extension, which the CLI itself runs without; the
+ * command is rebuilt from {@see PHP_BINARY} and `CLAW_SERVER_EXTENSION` (the `.so`, defaulting to the
+ * name resolved from php's extension_dir).
+ */
+final readonly class ServerClient
+{
+    private const int SPAWN_TIMEOUT_MS = 10_000;
+    private const int POLL_MS = 100;
+
+    private ServerLocator $locator;
+
+    public function __construct(
+        private HttpClientInterface $http,
+        private string $workspace,
+        private string $root,
+        private string $host = '127.0.0.1',
+        private int $port = 8787,
+    ) {
+        $this->locator = new ServerLocator($workspace);
+    }
+
+    /**
+     * The address of a server already answering for this workspace, or null when none is — so the CLI
+     * can say it is about to start one before {@see ensure()} does.
+     *
+     * @return array{host: string, port: int}|null
+     */
+    public function running(): ?array
+    {
+        $found = $this->locator->locate();
+
+        return $found !== null && $this->locator->alive($found['host'], $found['port'])
+            ? ['host' => $found['host'], 'port' => $found['port']]
+            : null;
+    }
+
+    /**
+     * The address of a live server for this workspace, starting one if none answers.
+     *
+     * @return array{host: string, port: int}
+     *
+     * @throws ClawException when no server can be reached and none can be started
+     */
+    public function ensure(): array
+    {
+        return $this->running() ?? $this->spawn();
+    }
+
+    /**
+     * Ask the server to start the issue's solver. Returns once the run is launched — the server owns
+     * it from there.
+     *
+     * @param array{host: string, port: int} $server
+     *
+     * @throws ClawException when the server refuses the start
+     */
+    public function startRun(array $server, string $key, string $issueId): void
+    {
+        $url = sprintf(
+            'http://%s:%d/api/projects/%s/issues/%s/start',
+            $server['host'],
+            $server['port'],
+            rawurlencode($key),
+            rawurlencode($issueId),
+        );
+
+        $response = $this->http->post($url, '', ['Content-Type: application/json']);
+
+        if ($response->status === 202) {
+            return;
+        }
+
+        if ($response->status === 409) {
+            throw new ClawException('a run for this issue is already active');
+        }
+
+        throw new ClawException("the server refused to start the run (HTTP {$response->status})");
+    }
+
+    /**
+     * The argv that launches a server, or null when one cannot be built (bin/claw is not where it
+     * should be). Returned as a list, not a shell string, so it carries no quoting to get wrong and can
+     * be handed to proc_open's array form on either platform. Pure, so the shape can be asserted without
+     * spawning anything.
+     *
+     * The extension defaults to the `.so` name php resolves from its extension_dir; on Windows (a `.dll`)
+     * or a non-standard install, set CLAW_SERVER_EXTENSION to the file to load.
+     *
+     * @return list<string>|null
+     */
+    public static function spawnCommand(string $root, string $host, int $port): ?array
+    {
+        $claw = $root . \DIRECTORY_SEPARATOR . 'bin' . \DIRECTORY_SEPARATOR . 'claw';
+
+        if (!is_file($claw)) {
+            return null;
+        }
+
+        $extension = getenv('CLAW_SERVER_EXTENSION');
+        $extension = $extension === false || $extension === '' ? 'true_async_server.so' : $extension;
+
+        return [
+            \PHP_BINARY, '-d', 'extension=' . $extension,
+            $claw, 'serve', '--host', $host, '--port', (string) $port,
+        ];
+    }
+
+    /**
+     * Start a server and wait for it to answer.
+     *
+     * @return array{host: string, port: int}
+     *
+     * @throws ClawException
+     */
+    private function spawn(): array
+    {
+        $command = self::spawnCommand($this->root, $this->host, $this->port);
+
+        if ($command === null) {
+            throw new ClawException('cannot start a server: bin/claw is not where it should be');
+        }
+
+        $this->launchDetached($command);
+
+        $waited = 0;
+
+        while ($waited < self::SPAWN_TIMEOUT_MS) {
+            $found = $this->locator->locate();
+
+            if ($found !== null && $this->locator->alive($found['host'], $found['port'])) {
+                return ['host' => $found['host'], 'port' => $found['port']];
+            }
+
+            usleep(self::POLL_MS * 1000);
+            $waited += self::POLL_MS;
+        }
+
+        throw new ClawException(
+            'the server did not come up within ' . (self::SPAWN_TIMEOUT_MS / 1000) . 's — is the server '
+            . 'extension available? (set CLAW_SERVER_EXTENSION to its .so/.dll path)',
+        );
+    }
+
+    /**
+     * Start the server as a process that outlives this CLI and holds none of its stdio.
+     *
+     * The two platforms detach differently, and neither is the shell `&` a terminal-launched CLI would
+     * leak its console through. POSIX: `setsid --fork` gives the server its own session and returns at
+     * once (without --fork setsid execs in place and proc_close would block for the server's life).
+     * Windows: `create_new_console` cuts it from this console so it survives the CLI exiting. Either way
+     * the descriptor spec points stdio at files, so the server never inherits the pipe we were called
+     * through.
+     *
+     * @param list<string> $command
+     */
+    private function launchDetached(array $command): void
+    {
+        $log = $this->workspace . \DIRECTORY_SEPARATOR . 'server.log';
+        $windows = \PHP_OS_FAMILY === 'Windows';
+
+        $descriptors = [
+            0 => ['file', $windows ? 'NUL' : '/dev/null', 'r'],
+            1 => ['file', $log, 'a'],
+            2 => ['file', $log, 'a'],
+        ];
+
+        if ($windows) {
+            $process = @proc_open($command, $descriptors, $pipes, null, null, [
+                'bypass_shell' => true,
+                'create_new_console' => true,
+                'create_process_group' => true,
+            ]);
+        } else {
+            $process = @proc_open(['setsid', '--fork', ...$command], $descriptors, $pipes);
+        }
+
+        if (\is_resource($process)) {
+            proc_close($process);
+        }
+    }
+}
diff --git a/tests/ServerClientTest.php b/tests/ServerClientTest.php
new file mode 100644
index 0000000..6e638ab
--- /dev/null
+++ b/tests/ServerClientTest.php
@@ -0,0 +1,116 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests;
+
+use Claw\Exceptions\ClawException;
+use Claw\Http\HttpResponse;
+use Claw\ServerClient;
+use Testo\Assert;
+use Testo\Test;
+use Tests\Support\FakeHttpClient;
+
+/**
+ * The CLI's thin-client side: how it reads the server's answer to a start, the address it targets, and
+ * the shape of the command it would spawn a server with. The spawn itself needs the server extension
+ * and is exercised elsewhere; here the pure decisions are pinned.
+ */
+final class ServerClientTest
+{
+    private string $workspace;
+
+    public function __construct()
+    {
+        $this->workspace = sys_get_temp_dir() . '/claw-client-' . bin2hex(random_bytes(6));
+        mkdir($this->workspace);
+    }
+
+    public function __destruct()
+    {
+        @rmdir($this->workspace);
+    }
+
+    private function client(HttpResponse $response): ServerClient
+    {
+        return new ServerClient(new FakeHttpClient($response), $this->workspace, '/opt/claw');
+    }
+
+    #[Test]
+    public function aStartAcceptedReturnsQuietly(): void
+    {
+        $http = new FakeHttpClient(new HttpResponse(202, ''));
+        // a 202 must return without throwing; that the POST was issued is the proof it ran
+        new ServerClient($http, $this->workspace, '/opt/claw')
+            ->startRun(['host' => '127.0.0.1', 'port' => 8787], 'proj', '7');
+
+        Assert::same(str_ends_with((string) $http->lastUrl, '/issues/7/start'), true);
+    }
+
+    #[Test]
+    public function anAlreadyActiveRunIsReportedNotSwallowed(): void
+    {
+        $threw = false;
+
+        try {
+            $this->client(new HttpResponse(409, '{"error":"a run for this issue is already active"}'))
+                ->startRun(['host' => '127.0.0.1', 'port' => 8787], 'proj', '7');
+        } catch (ClawException $e) {
+            $threw = true;
+            Assert::same(str_contains($e->getMessage(), 'already active'), true);
+        }
+
+        Assert::same($threw, true);
+    }
+
+    #[Test]
+    public function aServerErrorIsSurfaced(): void
+    {
+        $threw = false;
+
+        try {
+            $this->client(new HttpResponse(500, ''))
+                ->startRun(['host' => '127.0.0.1', 'port' => 8787], 'proj', '7');
+        } catch (ClawException $e) {
+            $threw = true;
+            Assert::same(str_contains($e->getMessage(), '500'), true);
+        }
+
+        Assert::same($threw, true);
+    }
+
+    #[Test]
+    public function theStartTargetsTheIssuesRunEndpointWithEscapedKeys(): void
+    {
+        $http = new FakeHttpClient(new HttpResponse(202, ''));
+        new ServerClient($http, $this->workspace, '/opt/claw')
+            ->startRun(['host' => '10.0.0.5', 'port' => 9000], 'a b/c', '7');
+
+        Assert::same($http->lastUrl, 'http://10.0.0.5:9000/api/projects/a%20b%2Fc/issues/7/start');
+    }
+
+    #[Test]
+    public function runningIsNullWhenNothingIsRecorded(): void
+    {
+        Assert::same($this->client(new HttpResponse(202, ''))->running(), null);
+    }
+
+    #[Test]
+    public function theSpawnCommandCarriesTheExtensionHostAndPort(): void
+    {
+        // bin/claw must exist under the root for a command to be built, so point the root at the repo
+        $command = ServerClient::spawnCommand(\dirname(__DIR__), '127.0.0.1', 8787) ?? [];
+
+        Assert::same(\in_array('serve', $command, true), true);
+        Assert::same(\in_array('--host', $command, true), true);
+        Assert::same(\in_array('127.0.0.1', $command, true), true);
+        Assert::same(\in_array('8787', $command, true), true);
+        Assert::same(array_any($command, static fn (string $a): bool => str_starts_with($a, 'extension=')), true);
+    }
+
+    #[Test]
+    public function noSpawnCommandWhenBinClawIsAbsent(): void
+    {
+        Assert::same(ServerClient::spawnCommand('/nowhere/at/all', '127.0.0.1', 8787), null);
+    }
+}