test: colluding-third adversarial tests (#3, Atomic Raven) — 22/22, 19 invariants + 3 known-defeats

test_swarmmetrics.py

@@ -408,12 +408,111 @@ def test_genuine_novel_concept_zero_echo():
     # for concepts that have had time to propagate.
 
 
+def test_colluding_third_party_echo():
+    """Adversarial case #3 (Atomic Raven, Colony 2026-07-28): three agents
+    in a trench coat manufacturing echo.
+
+    Eve introduces concepts → Mallory adopts them → Sybil adopts them.
+    All three are colluding. Echo gives Eve high score because her
+    concepts propagate (Mallory and Sybil pick them up). The echo
+    is "real" in the temporal sense (concepts do flow A→B→C) but
+    the whole chain is manufactured.
+
+    Echo catches non-colluding adversaries (no third-party adoption).
+    Echo CANNOT catch colluding adversaries (manufactured adoption).
+    This is a known-defeat: the instrument fails by design."""
+    msgs = []
+    # Eve introduces concepts
+    for i in range(5):
+        msgs.append({"from_id": "eve", "to_id": "mallory",
+                     "timestamp": now - 5*day + i*3600,
+                     "concepts": [f"colluded-concept-{i}"]})
+    # Mallory "adopts" them (by pre-arrangement)
+    for i in range(5):
+        msgs.append({"from_id": "mallory", "to_id": "sybil",
+                     "timestamp": now - 4*day + i*3600,
+                     "concepts": [f"colluded-concept-{i}"]})
+    # Sybil "independently" uses them too
+    for i in range(5):
+        msgs.append({"from_id": "sybil", "to_id": "frank",
+                     "timestamp": now - 3*day + i*3600,
+                     "concepts": [f"colluded-concept-{i}"]})
+    # Frank is innocent bystander — doesn't adopt
+    msgs.append({"from_id": "frank", "to_id": "grace",
+                 "timestamp": now - 2*day,
+                 "concepts": ["unrelated"]})
+
+    echo = score_echo(msgs)
+    eve_echo = echo.get("eve", 0)
+
+    # Eve gets positive echo because her concepts DO propagate
+    # through mallory→sybil. This is the manufactured adoption.
+    assert eve_echo > 0, \
+        f"Colluding adversary should get positive echo (manufactured adoption): {eve_echo}"
+
+    # The echo is indistinguishable from genuine propagation.
+    # Echo sees: concept introduced by eve → used later by mallory → used later by sybil.
+    # That's the same pattern as genuine diffusion.
+    # Detecting collusion requires social-graph analysis (is sybil independent?)
+    # or content analysis (are the adoptions semantically motivated?),
+    # not temporal echo alone.
+
+
+def test_colluding_vs_genuine_echo_indistinguishable():
+    """Complementary to colluding-third: genuine propagation and manufactured
+    propagation produce the same echo signature.
+
+    Genuine: alice → bob → charlie (organic adoption)
+    Colluded: eve → mallory → sybil (pre-arranged adoption)
+    Both should score similarly on echo — proving echo cannot distinguish them."""
+    msgs = []
+    # Genuine chain
+    msgs.append({"from_id": "alice", "to_id": "bob",
+                 "timestamp": now - 5*day,
+                 "concepts": ["genuine-idea"]})
+    msgs.append({"from_id": "bob", "to_id": "charlie",
+                 "timestamp": now - 4*day,
+                 "concepts": ["genuine-idea"]})
+    msgs.append({"from_id": "charlie", "to_id": "dave",
+                 "timestamp": now - 3*day,
+                 "concepts": ["genuine-idea"]})
+
+    # Colluded chain (same structure, different concept)
+    msgs.append({"from_id": "eve", "to_id": "mallory",
+                 "timestamp": now - 5*day + 100,
+                 "concepts": ["colluded-idea"]})
+    msgs.append({"from_id": "mallory", "to_id": "sybil",
+                 "timestamp": now - 4*day + 100,
+                 "concepts": ["colluded-idea"]})
+    msgs.append({"from_id": "sybil", "to_id": "frank",
+                 "timestamp": now - 3*day + 100,
+                 "concepts": ["colluded-idea"]})
+
+    echo = score_echo(msgs)
+    alice_echo = echo.get("alice", 0)
+    eve_echo = echo.get("eve", 0)
+
+    # Both should have positive echo
+    assert alice_echo > 0, f"Genuine should have echo: {alice_echo}"
+    assert eve_echo > 0, f"Colluded should have echo: {eve_echo}"
+
+    # And they should be similar (within 2x) — echo can't tell them apart
+    if max(alice_echo, eve_echo) > 0:
+        ratio = max(alice_echo, eve_echo) / max(min(alice_echo, eve_echo), 0.001)
+        assert ratio < 3.0, \
+            f"Genuine and colluded should score similarly: alice={alice_echo:.3f}, eve={eve_echo:.3f}, ratio={ratio:.1f}"
+
+
 # Run all tests
 # Split counter: invariants vs known-defeats (per ColonistOne, Colony 2026-07-28)
 # "18/18" mixes "instrument works" with "instrument fails as expected"
 tests = [v for k, v in sorted(globals().items()) if k.startswith("test_")]
 # Known-defeat tests: these ASSERT that the instrument fails
-known_defeats = {"test_f33_adversarial_synonym_padding"}  # F3.3 is beaten here
+known_defeats = {
+    "test_f33_adversarial_synonym_padding",  # F3.3 beaten by synonym padding
+    "test_colluding_third_party_echo",       # Echo beaten by manufactured adoption
+    "test_colluding_vs_genuine_echo_indistinguishable",  # Echo can't tell genuine from colluded
+}
 invariants = {t.__name__ for t in tests} - known_defeats
 
 passed = 0