CB-103: injector submits the prompt (Enter as a separate keystroke)

A delegated message was delivered into the worker's input box but never
submitted, so no task was ever processed: bridge_send blocked until timeout
while the worker sat idle with the prompt typed but not entered.

herdr's agent.send delivers text as a bracketed paste; a trailing carriage
return in that same call is swallowed as literal newline content, not Enter.
AgentControl.send now emits two keystroke events — the payload, then a
standalone "\r" — so the worker actually submits and runs the task.

Verified live (Claude Code v2.1.210, off-sub worker): full hands-off
bridge_send -> auto-submit -> worker computes -> bridge_reply round trip
returns the reply in ~41s. 62 tests green.

bridged/src/test/java/dev/ltms/bridged/herdr/AgentControlTest.java

@@ -0,0 +1,40 @@
+package dev.ltms.bridged.herdr;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/** Unit-level behaviour of {@link AgentControl} over a fake herdr. */
+class AgentControlTest {
+
+    /** The {@code text} of every agent.send, in call order. */
+    @SuppressWarnings("unchecked")
+    private static List<String> sendTexts(FakeHerdr herdr) {
+        return herdr.calls.stream()
+                .filter(c -> c.method().equals("agent.send"))
+                .map(c -> ((Map<String, Object>) c.params()).get("text").toString())
+                .toList();
+    }
+
+    @Test
+    void sendDeliversThePayloadThenAStandaloneSubmitKey() {
+        FakeHerdr herdr = new FakeHerdr();
+        new AgentControl(herdr).send("term_x", "do the thing");
+
+        // The Enter must be its own event — appended to the paste it would be swallowed as text.
+        assertEquals(List.of("do the thing", "\r"), sendTexts(herdr),
+                "payload paste first, then a separate carriage-return keystroke to submit it");
+    }
+
+    @Test
+    void sendPreservesEmbeddedNewlinesAndSubmitsOnlyOnce() {
+        FakeHerdr herdr = new FakeHerdr();
+        new AgentControl(herdr).send("term_x", "line1\nline2");
+
+        assertEquals(List.of("line1\nline2", "\r"), sendTexts(herdr),
+                "multiline content is delivered verbatim; a single trailing Enter submits it");
+    }
+}

bridged/src/test/java/dev/ltms/bridged/inject/InjectorTest.java

@@ -25,12 +25,18 @@ class InjectorTest {
     private final FakeHerdr herdr = new FakeHerdr();
     private final Injector injector = new Injector(new AgentControl(herdr));
 
-    /** Text of every agent.send, in order. */
+    /**
+     * The logical messages delivered, in order. AgentControl.send emits each delivery as two
+     * agent.send calls — the payload, then a standalone Enter keystroke ({@code "\r"}) to submit
+     * it; these tests assert delivery ordering/gating, not the submit event, so drop the bare
+     * carriage returns.
+     */
     @SuppressWarnings("unchecked")
     private List<String> sent() {
         return herdr.calls.stream()
                 .filter(c -> c.method().equals("agent.send"))
                 .map(c -> ((Map<String, Object>) c.params()).get("text").toString())
+                .filter(t -> !t.equals("\r"))
                 .toList();
     }
 
@@ -170,7 +176,9 @@ class InjectorTest {
                     @SuppressWarnings("unchecked")
                     Map<String, Object> p = (Map<String, Object>) c.params();
                     return p.get("text").toString();
-                }).toList());
+                })
+                .filter(t -> !t.equals("\r")) // drop the standalone submit keystroke
+                .toList());
     }
 
     @Test