feat(tracing): forward the journey name alongside the journey id

campus_python/tracing.py

@@ -33,6 +33,12 @@
 # action journey. Keep the two in lockstep.
 JOURNEY_ID_HEADER = "X-Journey-ID"
 
+# Mirror of campus.audit.middleware.journeys.ACTION_JOURNEY_NAME_HEADER
+# (campus#952): forwarded with the id so a child service's spans tag
+# the same human label (tags.journey_name) and journey cards show it
+# end to end. Keep the two in lockstep.
+JOURNEY_NAME_HEADER = "X-Journey-Name"
+
 # Mirror of campus.config.DEVICE_ID_HEADER (campus#837): forwarded so a
 # child service's span carries the caller's device identity when the
 # host stashed one (flask_campus's push_context sets g.device from the
@@ -75,10 +81,11 @@ def propagation_headers() -> dict[str, str]:
     tracing middleware turns the trace headers into a child span of the
     caller's span (#794, campus#816); the journeys middleware adopts
     X-Journey-ID so the child span joins the caller's action journey
-    (campus#828); the tracing middleware adopts X-Campus-Device for the
+    (campus#828), with X-Journey-Name carrying its human label
+    (campus#952); the tracing middleware adopts X-Campus-Device for the
     child span's device tag when it knows nothing better (campus#837).
     The three are independent: trace headers require span state on
-    flask.g (tracing middleware ran), the journey header only requires
+    flask.g (tracing middleware ran), the journey headers only require
     an active journey, the device header only requires a stashed
     g.device.
     """
@@ -97,6 +104,9 @@ def propagation_headers() -> dict[str, str]:
     journey_id = getattr(flask.g, "journey_id", None)
     if journey_id:
         headers[JOURNEY_ID_HEADER] = journey_id
+    journey_name = getattr(flask.g, "journey_name", None)
+    if journey_name:
+        headers[JOURNEY_NAME_HEADER] = journey_name
     device_id = getattr(flask.g, "device", None)
     if device_id:
         headers[DEVICE_ID_HEADER] = str(device_id)

tests/unit/test_trace_propagation.py

@@ -181,6 +181,52 @@ def test_journey_header_outside_trace_context(self):
         self.assertNotIn("X-Request-ID", captured["headers"])
 
 
+class TestJourneyNameForwarding(unittest.TestCase):
+    """Journey-label forwarding on SDK calls (campus#952).
+
+    When the host stashes a journey name (flask.g.journey_name — set by
+    flask_campus's @journey decorator or by the journeys middleware
+    adopting X-Journey-Name), SDK calls forward it alongside the id so
+    child services' spans tag the same journey_name.
+    """
+
+    def test_name_forwarded_with_journey_id(self):
+        app = flask.Flask(__name__)
+        client = _make_client()
+        captured = _capture_send(client)
+
+        with app.test_request_context("/"):
+            flask.g.journey_id = "uid-journey-abc123"
+            flask.g.journey_name = "campus.submissions.submit"
+            client.get("/ping")
+
+        self.assertEqual(
+            captured["headers"].get("X-Journey-Name"),
+            "campus.submissions.submit",
+        )
+        self.assertEqual(
+            captured["headers"].get("X-Journey-ID"), "uid-journey-abc123"
+        )
+
+    def test_no_name_no_header(self):
+        """A journey without a stashed name emits no name header."""
+        app = flask.Flask(__name__)
+        client = _make_client()
+        captured = _capture_send(client)
+
+        with app.test_request_context("/"):
+            flask.g.journey_id = "uid-journey-abc123"
+            client.get("/ping")
+
+        self.assertNotIn("X-Journey-Name", captured["headers"])
+
+    def test_name_lockstep_with_campus_middleware(self):
+        """The header name must match the campus journeys middleware's
+        adoption constant — the two modules carry keep-in-lockstep
+        notes and the whole chain breaks silently if they drift."""
+        self.assertEqual(tracing.JOURNEY_NAME_HEADER, "X-Journey-Name")
+
+
 class TestDeviceForwarding(unittest.TestCase):
     """Device forwarding on SDK calls (campus#837).