diff --git a/test/fixtures/documents/flow_patterns/composed.json b/test/fixtures/documents/flow_patterns/composed.json
new file mode 100644
index 00000000..09d67a2e
--- /dev/null
+++ b/test/fixtures/documents/flow_patterns/composed.json
@@ -0,0 +1,62 @@
+{
+  "schema_version": 1,
+  "id": "bdoc_01JHOLDPICKUP",
+  "revision": 1,
+  "metadata": {"name": "Hold pickup, confirmed and shelved"},
+  "accepts": ["hold.confirmed", "hold.collected", "hold.cancelled"],
+  "datamodel": [
+    {"id": "wants_confirmation", "description": "The desk confirms the hold."},
+    {"id": "held_on_shelf", "description": "The item waits on the hold shelf."}
+  ],
+  "root": {
+    "id": "blk_ROOT", "type": "core.sequence", "type_version": 1,
+    "slots": {"body": [
+      {"id": "blk_PLACE", "type": "core.send", "type_version": 2,
+       "config": {"event": "hold.placed"}},
+      {"id": "blk_PICKUP", "type": "core.parallel", "type_version": 1,
+       "config": {"lanes": ["confirm", "shelf"], "complete": "all"},
+       "slots": {
+         "lane_confirm": [
+           {"id": "blk_IF_CONFIRM", "type": "core.branch", "type_version": 1,
+            "config": {"arms": [{"slot": "arm_asked", "cond": "wants_confirmation"}]},
+            "slots": {"arm_asked": [
+              {"id": "blk_CONFIRM", "type": "core.group", "type_version": 1,
+               "slots": {
+                 "body": [
+                   {"id": "blk_TIMER", "type": "core.send", "type_version": 2,
+                    "config": {"event": "deadline.hold_confirm", "delay": "1d"}},
+                   {"id": "blk_WAIT", "type": "core.await", "type_version": 1,
+                    "config": {"event": "hold.confirmed"}}
+                 ],
+                 "interrupts": [
+                   {"id": "blk_EXPIRE", "type": "core.on_event", "type_version": 1,
+                    "config": {"event": "deadline.hold_confirm", "outcome": "abandon"}}
+                 ]
+               }}
+            ]}}
+         ],
+         "lane_shelf": [
+           {"id": "blk_IF_SHELF", "type": "core.branch", "type_version": 1,
+            "config": {"arms": [{"slot": "arm_asked", "cond": "held_on_shelf"}]},
+            "slots": {"arm_asked": [
+              {"id": "blk_SHELF", "type": "core.group", "type_version": 1,
+               "slots": {
+                 "body": [
+                   {"id": "blk_SHELVED", "type": "core.wait", "type_version": 2,
+                    "config": {"duration": "7d"}}
+                 ],
+                 "interrupts": [
+                   {"id": "blk_COLLECTED", "type": "core.on_event", "type_version": 1,
+                    "config": {"event": "hold.collected", "outcome": "abandon"}},
+                   {"id": "blk_CANCELLED", "type": "core.on_event", "type_version": 1,
+                    "config": {"event": "hold.cancelled", "outcome": "abandon"}}
+                 ]
+               }}
+            ]}}
+         ]
+       }},
+      {"id": "blk_CLOSE", "type": "core.send", "type_version": 2,
+       "config": {"event": "hold.closed"}}
+    ]}
+  }
+}
diff --git a/test/statifier_blocks/flow_patterns_composed_test.exs b/test/statifier_blocks/flow_patterns_composed_test.exs
new file mode 100644
index 00000000..14412c39
--- /dev/null
+++ b/test/statifier_blocks/flow_patterns_composed_test.exs
@@ -0,0 +1,301 @@
+defmodule StatifierBlocks.FlowPatternsComposedTest do
+  @moduledoc """
+  The three patterns `docs/guides/flow-patterns.md` shows one by one,
+  composed in one document: optional arms (a `core.parallel` whose lanes
+  are each guarded by a one-arm `core.branch`), with the bounded step (a
+  `core.group` carrying the deadline recipe around a `core.await`) in one
+  lane, and the park (a `core.group` whose body is a `core.wait` and whose
+  rail carries handlers) in the other.
+
+  The document is `test/fixtures/documents/flow_patterns/composed.json`, in
+  the guide's library world: a hold is placed, the desk may be asked to
+  confirm it within a day, the item may wait on the hold shelf for seven
+  days, and the hold is closed when both lanes are done. The compiled lines
+  each pattern carries are the guide's own lines, byte for byte, which is
+  what shows that nesting a pattern inside another changes nothing about it.
+
+  A pure test. Nothing here names LiveView, so it compiles and runs headless.
+  """
+
+  use ExUnit.Case, async: true
+
+  alias StatifierBlocks.{Compiler, Describe, Document, Finding, Palette, Publish, ViewModel}
+  alias StatifierBlocks.Map, as: BlockMap
+
+  @page "docs/guides/flow-patterns.md"
+  @composed "test/fixtures/documents/flow_patterns/composed.json"
+
+  # One day and seven days, as the host is asked to schedule the two
+  # delayed sends.
+  @one_day_ms 24 * 60 * 60 * 1000
+  @seven_days_ms 7 * @one_day_ms
+
+  describe "the composed document: publish and compile" do
+    # Sabotage: in the fixture, the parallel's `complete` set to `"every"`
+    # - red: Publish reports an error finding on `complete` (verified).
+    test "Publish reports no error, and it compiles under the core palette with no warning" do
+      document = composed()
+
+      assert for(
+               %Finding{severity: :error} = finding <- Publish.findings(document, palette(), %{}),
+               do: finding
+             ) == []
+
+      assert {:ok, compiled} = Compiler.compile(document, palette())
+      assert compiled.warnings == []
+      assert {:ok, _machine} = Statifier.compile(compiled.scxml)
+    end
+  end
+
+  describe "the composed document: the compiled chart" do
+    # Sabotage: in the fixture, the deadline handler (`blk_EXPIRE`) dropped
+    # from the group's rail - red here on the deadline's interrupt
+    # transition, and red on the two run tests that ask for the confirm
+    # lane and on the Describe test below; no Publish finding and no
+    # compile warning appear, so the first test stays green (verified).
+    # Sabotage: in the fixture, the deadline's send moved out of the group
+    # to just ahead of it in the branch arm - red here: the send is no
+    # longer inside the group (verified).
+    test "each pattern's timers and interrupt transitions are the guide's own lines" do
+      assert {:ok, compiled} = Compiler.compile(composed(), palette())
+
+      # The bounded step, inside the confirm lane's group: the guide's
+      # first pattern. The hold shelf, inside the shelf lane's group: the
+      # guide's third pattern.
+      for {group, lines} <- [
+            {"s_blk_CONFIRM",
+             [
+               ~s(<send delay="1d" event="deadline.hold_confirm" id="s_blk_TIMER__send"/>),
+               ~s(<transition event="deadline.hold_confirm" target="s_blk_EXPIRE__o_done">) <>
+                 ~s(<raise event="statifier_blocks.interrupt.abandon.s_blk_CONFIRM"/></transition>),
+               ~s(<transition event="statifier_blocks.interrupt.abandon.s_blk_CONFIRM" target="s_blk_CONFIRM__o_done" type="internal"/>),
+               ~s(<onexit><cancel sendid="s_blk_TIMER__send"/></onexit>)
+             ]},
+            {"s_blk_SHELF",
+             [
+               ~s(<send delay="7d" event="statifier_blocks.wait.blk_SHELVED" id="s_blk_SHELVED__send"/>),
+               ~s(<transition event="hold.collected" target="s_blk_COLLECTED__o_done">) <>
+                 ~s(<raise event="statifier_blocks.interrupt.abandon.s_blk_SHELF"/></transition>),
+               ~s(<transition event="done.state.s_blk_SHELF__body" target="s_blk_SHELF__o_done" type="internal"/>),
+               ~s(<transition event="statifier_blocks.interrupt.abandon.s_blk_SHELF" target="s_blk_SHELF__o_done" type="internal"/>),
+               ~s(<onexit><cancel sendid="s_blk_SHELVED__send"/></onexit>)
+             ]}
+          ],
+          line <- lines do
+        assert within(compiled.scxml, group, group <> "__o_done") =~ line
+        assert page() =~ line
+      end
+
+      for {lane, group} <- [{"confirm", "s_blk_CONFIRM"}, {"shelf", "s_blk_SHELF"}] do
+        lane_xml =
+          within(
+            compiled.scxml,
+            "s_blk_PICKUP__lane_" <> lane,
+            "s_blk_PICKUP__done_lane_" <> lane
+          )
+
+        assert lane_xml =~ within(compiled.scxml, group, group <> "__o_done")
+      end
+
+      # The optional arms around them: the guide's second pattern, with
+      # this document's lanes and guards.
+      for line <- [
+            ~s(<transition cond="wants_confirmation" target="s_blk_CONFIRM"/>) <>
+              ~s(<transition target="s_blk_IF_CONFIRM__o_done"/>),
+            ~s(<transition cond="held_on_shelf" target="s_blk_SHELF"/>) <>
+              ~s(<transition target="s_blk_IF_SHELF__o_done"/>),
+            ~s(<transition event="done.state.s_blk_CONFIRM" target="s_blk_IF_CONFIRM__o_done" type="internal"/>),
+            ~s(<transition event="done.state.s_blk_SHELF" target="s_blk_IF_SHELF__o_done" type="internal"/>),
+            ~s(<transition event="done.state.s_blk_IF_CONFIRM" target="s_blk_PICKUP__done_lane_confirm" type="internal"/>),
+            ~s(<transition event="done.state.s_blk_IF_SHELF" target="s_blk_PICKUP__done_lane_shelf" type="internal"/>),
+            ~s(<transition event="done.state.s_blk_PICKUP__run" target="s_blk_PICKUP__o_done" type="internal"/>),
+            ~s(<transition event="done.state.s_blk_PICKUP" target="s_blk_CLOSE" type="internal"/>)
+          ] do
+        assert compiled.scxml =~ line
+      end
+    end
+  end
+
+  describe "the composed document: the chart, run" do
+    setup do
+      {:ok, compiled} = Compiler.compile(composed(), palette())
+      {:ok, machine} = Statifier.compile(compiled.scxml)
+
+      %{machine: machine}
+    end
+
+    # Sabotage: in `Cancels.onexit/2`, emitted no `<cancel>` element - red:
+    # the bound abandons the group and leaves its day-long timer behind
+    # (verified).
+    test "both asked: each lane arms its own deadline, and the bound fails open inside its lane",
+         ctx do
+      {machine_state, effects} = start(ctx.machine, true, true)
+
+      assert sent(effects) == ["hold.placed"]
+
+      assert delayed(effects) == [
+               {"deadline.hold_confirm", @one_day_ms},
+               {"statifier_blocks.wait.blk_SHELVED", @seven_days_ms}
+             ]
+
+      assert Statifier.active_leaf_states(machine_state) ==
+               MapSet.new([
+                 "s_blk_WAIT__waiting",
+                 "s_blk_EXPIRE__armed",
+                 "s_blk_SHELVED__waiting",
+                 "s_blk_COLLECTED__armed",
+                 "s_blk_CANCELLED__armed"
+               ])
+
+      {:ok, machine_state, effects} =
+        Statifier.send_event(machine_state, "deadline.hold_confirm")
+
+      assert sent(effects) == []
+      assert cancelled(effects) == ["s_blk_TIMER__send"]
+
+      assert Statifier.active_leaf_states(machine_state) ==
+               MapSet.new([
+                 "s_blk_PICKUP__done_lane_confirm",
+                 "s_blk_SHELVED__waiting",
+                 "s_blk_COLLECTED__armed",
+                 "s_blk_CANCELLED__armed"
+               ])
+
+      {:ok, machine_state, effects} = Statifier.send_event(machine_state, "hold.collected")
+
+      assert Statifier.active_leaf_states(machine_state) == MapSet.new(["s_blk_ROOT__o_done"])
+      assert sent(effects) == ["hold.closed"]
+      assert cancelled(effects) == ["s_blk_SHELVED__send"]
+    end
+
+    # Sabotage: in the fixture, the two branches' conditions swapped - red:
+    # the shelf lane parks and the confirm lane arms no deadline (verified).
+    test "only the confirm lane asked: the bound alone ends the pickup", ctx do
+      {machine_state, effects} = start(ctx.machine, true, false)
+
+      assert delayed(effects) == [{"deadline.hold_confirm", @one_day_ms}]
+
+      assert Statifier.active_leaf_states(machine_state) ==
+               MapSet.new([
+                 "s_blk_WAIT__waiting",
+                 "s_blk_EXPIRE__armed",
+                 "s_blk_PICKUP__done_lane_shelf"
+               ])
+
+      {:ok, machine_state, effects} =
+        Statifier.send_event(machine_state, "deadline.hold_confirm")
+
+      assert Statifier.active_leaf_states(machine_state) == MapSet.new(["s_blk_ROOT__o_done"])
+      assert sent(effects) == ["hold.closed"]
+      assert cancelled(effects) == ["s_blk_TIMER__send"]
+    end
+
+    # Sabotage: in the fixture, the shelf branch's condition set to `true`
+    # - red: the chart parks on the hold shelf for a hold that asked for
+    # neither lane (verified).
+    test "neither asked: every lane finishes at once, with no timer, and the hold is closed",
+         ctx do
+      {machine_state, effects} = start(ctx.machine, false, false)
+
+      assert Statifier.active_leaf_states(machine_state) == MapSet.new(["s_blk_ROOT__o_done"])
+      assert sent(effects) == ["hold.placed", "hold.closed"]
+      assert delayed(effects) == []
+    end
+  end
+
+  describe "the composed document: what Describe and the Map show" do
+    # Sabotage: in the fixture, the lane `shelf` renamed `rack` (in
+    # `lanes` and its slot key) - red: the Map's second lane is titled
+    # `rack`, not `shelf` (verified).
+    test "Describe names every arm, and the Map draws both lanes and every edge" do
+      document = composed()
+      lines = Describe.render(Describe.outline(document, palette(), []), [])
+
+      for line <- [
+            "Run 2 lanes at the same time (all of)",
+            "After Run 2 lanes at the same time (done), Send hold.closed",
+            "The branch: when wants_confirmation, Run interruptible steps",
+            "The branch: when held_on_shelf, Run interruptible steps",
+            "In 1 day, send deadline.hold_confirm",
+            "When deadline.hold_confirm, abandon",
+            "On deadline.hold_confirm, When deadline.hold_confirm, abandon abandons the group",
+            "In 1 day, deadline.hold_confirm reaches When deadline.hold_confirm, abandon",
+            "Wait 7d",
+            "Wait 7d (done) ends the group",
+            "On hold.collected, When hold.collected, abandon abandons the group",
+            "On hold.cancelled, When hold.cancelled, abandon abandons the group"
+          ] do
+        assert line in lines
+      end
+
+      assert Enum.count(lines, &(&1 == ~s[Decide: When "asked", otherwise (one of)])) == 2
+      assert Enum.count(lines, &(&1 == "The branch: otherwise, the end of the branch")) == 2
+
+      graph = document |> ViewModel.build(palette(), []) |> BlockMap.graph()
+      parallel = find_node(graph, "blk_PICKUP")
+
+      assert for(lane <- parallel["children"], do: {lane["id"], lane["title"]}) == [
+               {"blk_PICKUP/lane_confirm", "confirm"},
+               {"blk_PICKUP/lane_shelf", "shelf"}
+             ]
+
+      assert BlockMap.interrupts(graph) == [
+               %{"from" => "blk_EXPIRE", "group" => "blk_CONFIRM", "to" => "exit"},
+               %{"from" => "blk_COLLECTED", "group" => "blk_SHELF", "to" => "exit"},
+               %{"from" => "blk_CANCELLED", "group" => "blk_SHELF", "to" => "exit"}
+             ]
+
+      assert BlockMap.timers(graph) == [
+               %{
+                 "from" => "blk_TIMER",
+                 "to" => "blk_EXPIRE",
+                 "event" => "deadline.hold_confirm",
+                 "delay" => "1d"
+               }
+             ]
+    end
+  end
+
+  defp page, do: File.read!(@page)
+
+  defp palette, do: Palette.core()
+
+  defp composed do
+    {:ok, document} = Document.from_json(File.read!(@composed))
+    document
+  end
+
+  # Starts the chart with the hold's two answers in the datamodel, as a host
+  # supplies them.
+  defp start(machine, wants_confirmation, held_on_shelf) do
+    Statifier.initialize(machine,
+      datamodel: %{
+        "wants_confirmation" => wants_confirmation,
+        "held_on_shelf" => held_on_shelf
+      }
+    )
+  end
+
+  # The compiled chart's state `id`, from its opening tag to the final
+  # `final` it closes with: everything the state holds that this test
+  # looks for.
+  defp within(scxml, id, final) do
+    [_before, rest] = String.split(scxml, ~s(<state id="#{id}"), parts: 2)
+    [inside, _after] = String.split(rest, ~s(<final id="#{final}"), parts: 2)
+    inside
+  end
+
+  defp sent(effects), do: for({:send, send} <- effects, do: send.event)
+
+  defp delayed(effects),
+    do: for({:send_delayed, send} <- effects, do: {send.event, send.delay_ms})
+
+  defp cancelled(effects), do: for({:cancel, cancel} <- effects, do: cancel.send_id)
+
+  defp find_node(%{"id" => id} = node, id), do: node
+
+  defp find_node(%{"children" => children}, id),
+    do: Enum.find_value(children, &find_node(&1, id))
+
+  defp find_node(_node, _id), do: nil
+end