tests/test_face_tracker.cpp

@@ -192,6 +192,13 @@ TEST_CASE("a track within the extinction window is still a candidate",
 
     Embedding person = at_sim(0, 1, 0.99f);
     int id_pre = r.track_of(frame(0.0, 10, 10, person));
+
+    // Identify it while it is still on screen. Since 1477c53 a DORMANT track is
+    // only associable if it was owned -- an anonymous one has no actor to
+    // re-attach to, so it is dropped from the pool a line before the horizon is
+    // ever consulted. Without this the test cannot reach what it is about.
+    r.reg->observe(id_pre, /*actor=*/0, /*posterior=*/0.99f, person);
+
     r.track_of(frame(1.0, 300, 300, axis(7), /*is_cut=*/true));
 
     // Back inside the window: the same person continues the same track, so the

tests/test_track_registry.cpp

@@ -415,15 +415,21 @@ TEST_CASE("a track is not reaped until the evidence clock passes it",
 }
 
 /// TRACES: UT-001 | AR-008, AR-013 | SR-002
-TEST_CASE("a track retired from association is still open to evidence",
+TEST_CASE("association and reaping retire a track on the same clock",
           "[registry][AR-008]") {
-    // The two clocks answer different questions and must not share an answer.
-    // Association asks "may this detection link to that track?" on the tracker's
-    // clock; reaping asks "is that track finished?" and cannot answer until the
-    // votes are in. Deferring both to the evidence clock was the second half of
-    // this bug: retired tracks lingered in the candidate pool for as long as the
-    // matcher lagged, so a new face re-associated onto a long-dead track and two
-    // people merged into one window.
+    // Renamed and rewritten for the unified clock. This test used to assert the
+    // opposite arrangement -- association answered on the tracker's clock while
+    // reaping answered on the evidence watermark -- and it was written when that
+    // was true. It is not true now: candidates() and reap_locked() take the SAME
+    // clock and the SAME threshold, so "retired from association" and "reaped"
+    // are one event, and the interval the old name described does not exist.
+    //
+    // Both halves of the AR-013 bug are visible here. Offering on a LOOSER
+    // horizon than the reap left retired tracks in the candidate pool for as
+    // long as the matcher lagged, so a new face re-associated onto a long-dead
+    // track and two people merged into one window. Reaping on a looser horizon
+    // than the offer killed tracks whose votes were still in flight. One clock
+    // makes both unrepresentable.
     TrackRegistry reg(cfg(/*extinction=*/5.0), disc());
     Sink sink; sink.attach(reg);
     reg.expect_evidence();
@@ -432,21 +438,37 @@ TEST_CASE("a track retired from association is still open to evidence",
     {
         auto s = reg.begin_frame(0.0);
         id = s.create(0.0, axis(1));
+    }
+    // Owned before it goes dormant, for the reason above: an unidentified
+    // dormant track is not a candidate at any horizon (1477c53).
+    reg.observe(id, 7, 0.99f, axis(1));
+    {
+        auto s = reg.begin_frame(0.0);
         s.mark_lost(id, 0.0);
     }
 
     {
-        auto s = reg.begin_frame(3.0);          // inside the window
+        auto s = reg.begin_frame(3.0);          // watermark inside the window
         CHECK(s.candidates().size() == 1);      // still associable
     }
+    // The tracker races far past the horizon while the matcher lags. This
+    // retires nothing, and that is the point of the watermark: the clock that
+    // decides has not moved, so the track is still offered.
     {
-        auto s = reg.begin_frame(50.0);         // far outside it
-        CHECK(s.candidates().empty());          // retired from association...
+        auto s = reg.begin_frame(50.0);
+        CHECK(s.candidates().size() == 1);
     }
-    // ...but not gone, and still able to receive the votes in flight for it.
+    // Which is what keeps it able to receive the votes still in flight for it.
     reg.observe(id, 7, 0.99f, axis(1));
     CHECK(reg.dropped_votes() == 0);
+
+    // Only the watermark passing last_seen + extinction retires it -- and the
+    // same call reaps and emits it, so there is no interval in between.
     reg.advance_evidence(50.0);
+    {
+        auto s = reg.begin_frame(50.0);
+        CHECK(s.candidates().empty());
+    }
     REQUIRE(sink.claims.size() == 1);
     CHECK(sink.claims[0].actor_idx == 7);
 }