fix(android): the cast header is everything before the first moof

The node's first chunk can be the 28-byte ftyp alone, the moov in the next;
served as the header, the receiver had no moov and gave up. A receiver early
for the header now waits for all of it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/packages/meshbay-android/app/src/test/kotlin/org/meshbay/client/CastRelayTest.kt b/packages/meshbay-android/app/src/test/kotlin/org/meshbay/client/CastRelayTest.kt
index 1c604d0..5d3125f 100644
--- a/packages/meshbay-android/app/src/test/kotlin/org/meshbay/client/CastRelayTest.kt
+++ b/packages/meshbay-android/app/src/test/kotlin/org/meshbay/client/CastRelayTest.kt
@@ -106,6 +106,31 @@ class CastRelayTest {
         assertArrayEquals("header, then each fragment once", stream, reply.body)
     }
 
+    @Test fun `a header split across chunks is served whole`() {
+        // Measured on a fresh start: the first chunk was the 28-byte ftyp
+        // alone, the moov came in the next push. Served as the header, the
+        // receiver had no moov and gave up — the first cast failed every time.
+        val ftyp = box("ftyp", 20)
+        val moov = box("moov", 2124)
+        val started = relay.start(ftyp, null)
+        val url = started.getString("url")
+        // The page pushes the first chunk too, then the rest.
+        relay.push(ftyp); relay.push(moov); relay.push(fragment(1)); relay.push(fragment(2))
+        val reply = get(url, readBytes = ftyp.size + moov.size + fragment(1).size + fragment(2).size)
+        assertArrayEquals(ftyp + moov + fragment(1) + fragment(2), reply.body)
+    }
+
+    @Test fun `a receiver early for the header waits for all of it`() {
+        val ftyp = box("ftyp", 20)
+        val moov = box("moov", 2124)
+        val url = relay.start(ftyp, null).getString("url")
+        relay.push(ftyp)
+        val late = Thread { Thread.sleep(400); relay.push(moov); relay.push(fragment(1)) }.apply { start() }
+        val reply = get(url, readBytes = ftyp.size + moov.size + fragment(1).size)
+        late.join()
+        assertArrayEquals(ftyp + moov + fragment(1), reply.body)
+    }
+
     @Test fun `the token is required and unguessable`() {
         val url = relay.start(null, null).getString("url")
         val token = url.substringAfter("t=")