perf(constructor): park the bootstrap-section SPOT carrier in compose too

On a compose host no applications carrier sits between the add_host
placement and the stage-wide park, so every SPOT-reading task of the
pre-flight checks and the package batch rendered the applications SPOT
cold. In the galaxyserver production deploy of 2fd6c6d (compose) the
seven tasks from "Fail when a docker network does not belong to its
entity" to "Install the packages of every role this host may run"
took 10.3 to 12.3 s each, 77.4 s together, while the explicit SPOT
renders of the same run took 9.2 to 9.8 s; echoserver 2fd6c6d and
galaxyserver 9e1cf40 show the same pattern.

778c18fb23 parked this carrier only in swarm because "in compose the
section runs in about a second". The pre-flight checks (a67dd9b372)
and the package batch (18ea75049e) came later and changed that. Swarm
already runs this section under the carrier, and the key still rejects
a carrier whose roles tree or stable variable signature changed, so
compose now parks it as swarm does.

Projected from the log: about 60 s less per compose deploy (seven cold
renders become one), not yet re-measured on a deploy.

| 🎯 Fix | 💥 Break | 🌱 Efficiency | ⚡ Speed | 🛡️ Security | 🏆 Score | Gate |
| --- | --- | --- | --- | --- | --- | --- |
| 88 % | 5 % | – | – | ~100 % | 84 | ⛔ fix 88 % < 90 |

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

plugins/action/applications_carrier.py

@@ -14,8 +14,8 @@ the token store digest and ``inventory_hostname``::
 
 ``tasks/stages/01_constructor.yml`` parks three of them: a block-scoped one
 for the merge block, which it drops again at the block's end, one after the
-``add_host`` tasks for the swarm bootstrap roles, parked only when
-``DEPLOYMENT_MODE`` is ``swarm``, and the stage-wide one after the token store. ``merged_applications_cache_key`` reads ``group_names``, so a
+``add_host`` tasks for the pre-flight checks, the package batch and the
+bootstrap roles, and the stage-wide one after the token store. ``merged_applications_cache_key`` reads ``group_names``, so a
 carrier whose groups no longer match is rejected and the reader renders
 afresh. ``merged_users_cache_key`` adds a digest of the tokens the users are
 hydrated from (the tokens file, or the ``sys_token_store_users`` fact once the

tasks/stages/01_constructor.yml

@@ -68,7 +68,6 @@
 
 - name: 🧊 Render the applications SPOT once for the bootstrap section
   applications_carrier: {}
-  when: IS_SWARM_MODE
 
 - name: "🛫 Pre-flight checks"
   ansible.builtin.include_tasks: ./tasks/utils/constructor/preflight.yml

tests/integration/ansible/playbooks/test_constructor_carriers.py

@@ -0,0 +1,73 @@
+import unittest
+
+from utils.cache.yaml import load_yaml_any
+
+from . import PROJECT_ROOT
+
+CONSTRUCTOR = PROJECT_ROOT / "tasks" / "stages" / "01_constructor.yml"
+PLACEMENT = "./tasks/utils/constructor/placement.yml"
+PREFLIGHT = "🛫 Pre-flight checks"
+
+
+def _carrier(task: dict) -> dict | None:
+    args = task.get("applications_carrier")
+    return args if isinstance(args, dict) else None
+
+
+def _parks(task: dict) -> bool:
+    args = _carrier(task)
+    return args is not None and not args.get("clear", False)
+
+
+def _clears(task: dict) -> bool:
+    args = _carrier(task)
+    return args is not None and bool(args.get("clear", False))
+
+
+class TestConstructorBootstrapCarrier(unittest.TestCase):
+    def setUp(self) -> None:
+        self.tasks = load_yaml_any(str(CONSTRUCTOR))
+        self.placement = next(
+            index
+            for index, task in enumerate(self.tasks)
+            if task.get("ansible.builtin.include_tasks") == PLACEMENT
+        )
+        self.preflight = next(
+            index
+            for index, task in enumerate(self.tasks)
+            if task.get("name") == PREFLIGHT
+        )
+        self.stage_wide = next(
+            index
+            for index, task in enumerate(self.tasks)
+            if _parks(task) and _carrier(task).get("provider_view")
+        )
+
+    def test_the_pre_flight_checks_read_a_carrier_in_every_deploy_mode(self):
+        window = self.tasks[self.placement + 1 : self.preflight]
+        parks = [task for task in window if _parks(task)]
+
+        self.assertEqual(
+            len(parks),
+            1,
+            "one carrier must be parked between the add_host placement and the "
+            "pre-flight checks, or every check renders the SPOT cold",
+        )
+        self.assertNotIn(
+            "when",
+            parks[0],
+            "the pre-flight checks and the package batch read the SPOT in compose "
+            "as in swarm, so the carrier must not depend on the deploy mode",
+        )
+
+    def test_no_carrier_is_dropped_before_the_stage_wide_park(self):
+        window = self.tasks[self.placement + 1 : self.stage_wide]
+
+        self.assertEqual(
+            [task["name"] for task in window if _clears(task)],
+            [],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()