fix: make HLS edge start idempotent

Treat an already-started HLS edge media session as a successful stream.start response so the edge reconciler can race safely with explicit cluster starts.

lib/sender/management/stream_lifecycle.ex

@@ -299,7 +299,10 @@ defmodule TribeOne.TribesPlugin.Sender.Management.StreamLifecycle do
         Map.get(params, "backend_restart_max_delay_ms")
       )
 
-    MediaSession.start_hls_edge(generation, opts)
+    case MediaSession.start_hls_edge(generation, opts) do
+      {:error, {:already_started, pid}} when is_pid(pid) -> {:ok, pid}
+      result -> result
+    end
   end
 
   defp generation(%{"generation_id" => generation_id}, ash_opts) when is_binary(generation_id) do

test/sender/management_test.exs

@@ -450,6 +450,69 @@ defmodule TribeOne.TribesPlugin.Sender.ManagementTest do
     assert edge["source_endpoint_id"] == source["id"]
   end
 
+  test "stream lifecycle treats an already reconciled HLS edge session as running" do
+    node_pubkey = String.duplicate("d", 64)
+    assert {:ok, _node} = cluster_node(node_pubkey)
+
+    assert {:ok, %{"endpoint" => source}} =
+             Topology.upsert_endpoint(@context, %{
+               "type" => "external_origin",
+               "display_name" => "Mux",
+               "hls_base_url" => "https://origin.example/sender/hls"
+             })
+
+    assert {:ok, %{"endpoint" => edge}} =
+             Topology.upsert_endpoint(@context, %{
+               "type" => "tribes_edge",
+               "node_pubkey" => node_pubkey,
+               "source_endpoint_id" => source["id"],
+               "display_name" => "Local edge",
+               "metadata" => %{"source_tls_verify" => false}
+             })
+
+    assert {:ok, stream} =
+             Streaming.create_stream(
+               %{slug: "edge-idempotent-test", title: "Edge Idempotent Test"},
+               Management.ash_opts(@context)
+             )
+
+    assert {:ok, generation} =
+             Streaming.create_stream_generation(
+               %{
+                 stream_id: stream.id,
+                 status: :live,
+                 started_at: DateTime.utc_now() |> DateTime.truncate(:second),
+                 primary_origin_endpoint_id: source["id"]
+               },
+               Management.ash_opts(@context)
+             )
+
+    assert {:ok, %{started: 1, skipped: 0, errors: []}} =
+             EdgeSessionReconciler.reconcile_once(
+               ash_opts: Management.ash_opts(@context),
+               node_pubkey_fun: fn -> {:ok, node_pubkey} end,
+               backend: EdgeBackend
+             )
+
+    reconciled_pid = MediaSession.whereis(:hls_edge, generation.id)
+    assert is_pid(reconciled_pid)
+
+    assert {:ok, %{"session" => started}} =
+             StreamLifecycle.start(@context, %{
+               "mode" => "hls_edge",
+               "endpoint_id" => edge["id"],
+               "generation_id" => generation.id,
+               "source_tls_verify" => false,
+               backend: EdgeBackend
+             })
+
+    assert started["role"] == "hls_edge"
+    assert started["status"] == "running"
+    assert started["pid"] == inspect(reconciled_pid)
+
+    assert :ok = MediaSession.stop_generation(generation.id)
+  end
+
   test "stream lifecycle marks failed media startup attempts inactive" do
     previous_ffmpeg = System.get_env("SENDER_FFMPEG_EXECUTABLE")
     System.put_env("SENDER_FFMPEG_EXECUTABLE", "sender-missing-ffmpeg-test")