feat(flights): stamp source attribution on every flight record

Pre-fix, adsb.lol records (the primary source for most flights) carried
no source marker. OpenSky records got is_opensky: True and supplementals
got supplemental_source, so any UI inspecting source labels saw
OpenSky/airplanes.live records as explicitly tagged and adsb.lol records
as "unlabeled" — making it look like adsb.lol wasn't being used at all
even though it's the primary source.

Changes:

* _fetch_adsb_lol_regions stamps source="adsb.lol" on each aircraft
  before returning, so the tag survives the OpenSky dedupe-by-hex merge.
* OpenSky records get source="OpenSky" (alongside is_opensky=True for
  back-compat).
* military fetcher tags source on both adsb.lol and airplanes.live
  records before they're merged, and propagates source into the
  military_flights and uavs output dicts.
* _classify_and_publish promotes the explicit source field into the
  published flight dict. Falls back to legacy supplemental_source if
  source is absent. Final fallback "adsb.lol" preserves prior behavior
  for any caller synthesizing records without going through a fetcher.

8 new tests cover the published-dict propagation, OpenSky tagging,
supplemental fallback, explicit-wins precedence, default behavior, the
adsb.lol regional fetcher tagging, and the military output dict.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/services/fetchers/flights.py

@@ -459,6 +459,18 @@ def _classify_and_publish(all_adsb_flights):
 
             ac_category = "heli" if model_upper in _HELI_TYPES_BACKEND else "plane"
 
+            # Source attribution: prefer the explicit ``source`` tag stamped
+            # at fetch time (adsb.lol, OpenSky). If absent, fall back to the
+            # legacy ``supplemental_source`` (airplanes.live, adsb.fi) so
+            # supplementals are still attributed without changing their
+            # tagger. Final fallback "adsb.lol" preserves prior behavior for
+            # any caller that synthesizes records without going through one
+            # of our fetchers (e.g. tests).
+            source = (
+                f.get("source")
+                or f.get("supplemental_source")
+                or "adsb.lol"
+            )
             flights.append(
                 {
                     "callsign": flight_str,
@@ -480,6 +492,7 @@ def _classify_and_publish(all_adsb_flights):
                     "airline_code": airline_code,
                     "aircraft_category": ac_category,
                     "nac_p": f.get("nac_p"),
+                    "source": source,
                 }
             )
         except (ValueError, TypeError, KeyError, AttributeError) as loop_e:
@@ -849,7 +862,15 @@ def _fetch_adsb_lol_regions():
             res = fetch_with_curl(url, timeout=10)
             if res.status_code == 200:
                 data = res.json()
-                return data.get("ac", [])
+                aircraft = data.get("ac", [])
+                # Stamp the source at the fetch site so attribution survives
+                # the OpenSky/supplemental dedupe-by-hex merge downstream.
+                # Previously adsb.lol records carried no marker while OpenSky
+                # records got ``is_opensky: True`` — which made flight tooltips
+                # look like everything came from OpenSky.
+                for a in aircraft:
+                    a["source"] = "adsb.lol"
+                return aircraft
         except (
             requests.RequestException,
             ConnectionError,
@@ -932,6 +953,7 @@ def _enrich_with_opensky_and_supplemental(adsb_flights):
                                     "gs": (s[9] * 1.94384) if s[9] else 0,
                                     "t": "Unknown",
                                     "is_opensky": True,
+                                    "source": "OpenSky",
                                 }
                             )
                     elif os_res.status_code == 429:

backend/services/fetchers/military.py

@@ -171,6 +171,7 @@ def fetch_military_flights():
                 h = a.get("hex", "").lower()
                 if h and h not in seen_hex:
                     seen_hex.add(h)
+                    a["source"] = "adsb.lol"
                     all_mil_ac.append(a)
     except Exception as e:
         logger.warning(f"adsb.lol mil fetch failed: {e}")
@@ -182,6 +183,7 @@ def fetch_military_flights():
                 h = a.get("hex", "").lower()
                 if h and h not in seen_hex:
                     seen_hex.add(h)
+                    a["source"] = "airplanes.live"
                     all_mil_ac.append(a)
             logger.info(f"airplanes.live mil: +{len(resp2.json().get('ac', []))} raw, {len(all_mil_ac)} total unique")
     except Exception as e:
@@ -234,6 +236,7 @@ def fetch_military_flights():
                             "registration": f.get("r", "N/A"),
                             "icao24": icao_hex,
                             "squawk": f.get("squawk", ""),
+                            "source": f.get("source") or "adsb.lol",
                         })
                         continue
 
@@ -258,7 +261,8 @@ def fetch_military_flights():
                         "model": f.get("t", "Unknown"),
                         "icao24": icao_hex,
                         "speed_knots": speed_knots,
-                        "squawk": f.get("squawk", "")
+                        "squawk": f.get("squawk", ""),
+                        "source": f.get("source") or "adsb.lol",
                     })
                 except Exception as loop_e:
                     logger.error(f"Mil flight interpolation error: {loop_e}")