diff --git a/tests/testBehavior.cpp b/tests/testBehavior.cpp
index c07c083..10a2950 100644
--- a/tests/testBehavior.cpp
+++ b/tests/testBehavior.cpp
@@ -313,3 +313,165 @@ VF_TEST(timeLimitCutsOffAChildThatNeverSettles) {
     CHECK_EQ(runs, 4);
 }
 
+VF_TEST(parallelSettlesOnItsSuccessAndFailureThresholds) {
+    int slowRuns = 0;
+    int slowProgress = 0;
+
+    auto wide = std::unique_ptr<ParallelNode>(new ParallelNode("parallel", 2, 2));
+    wide->add(constantAction("ok", BehaviorStatus::Success, nullptr));
+    wide->add(slowAction("slow", 2, &slowRuns, &slowProgress));
+    wide->add(constantAction("nope", BehaviorStatus::Failure, nullptr));
+
+    BehaviorTree tree(std::move(wide));
+    BehaviorContext ctx;
+
+    // One success, one failure, one still running: neither threshold is met.
+    CHECK(tree.tick(ctx) == BehaviorStatus::Running);
+    CHECK(tree.tick(ctx) == BehaviorStatus::Running);
+    // The slow child succeeds on its third visit, which is the second success.
+    CHECK(tree.tick(ctx) == BehaviorStatus::Success);
+    CHECK_EQ(slowRuns, 3);
+
+    auto doomed = std::unique_ptr<ParallelNode>(new ParallelNode("parallel", 3, 2));
+    doomed->add(constantAction("no", BehaviorStatus::Failure, nullptr));
+    doomed->add(constantAction("alsoNo", BehaviorStatus::Failure, nullptr));
+    doomed->add(constantAction("yes", BehaviorStatus::Success, nullptr));
+    BehaviorTree unlucky(std::move(doomed));
+    CHECK(unlucky.tick(ctx) == BehaviorStatus::Failure);
+}
+
+VF_TEST(anOverDeepTreeIsRejectedInsteadOfOverflowingTheStack) {
+    std::unique_ptr<BehaviorNode> node = constantAction("leaf", BehaviorStatus::Success, nullptr);
+    for (int level = 0; level < maxBehaviorDepth + 12; ++level) {
+        node = std::unique_ptr<BehaviorNode>(new InverterNode("wrap", std::move(node)));
+    }
+
+    BehaviorTree tree(std::move(node));
+    CHECK(!tree.structureValid());
+    CHECK(tree.stats().depth > maxBehaviorDepth);
+    CHECK_EQ(tree.stats().nodeCount, maxBehaviorDepth + 13);
+
+    BehaviorContext ctx;
+    CHECK(tree.tick(ctx) == BehaviorStatus::Failure);
+    CHECK_EQ(ctx.tick, 0);
+    CHECK_EQ(tree.tickCount(), 0);
+}
+
+VF_TEST(aTreeExactlyAtTheDepthLimitStillRuns) {
+    std::unique_ptr<BehaviorNode> node = constantAction("leaf", BehaviorStatus::Success, nullptr);
+    for (int level = 0; level < maxBehaviorDepth - 1; ++level) {
+        node = std::unique_ptr<BehaviorNode>(new InverterNode("wrap", std::move(node)));
+    }
+
+    BehaviorTree tree(std::move(node));
+    CHECK_EQ(tree.stats().depth, maxBehaviorDepth);
+    CHECK(tree.structureValid());
+
+    BehaviorContext ctx;
+    tree.tick(ctx);
+    CHECK_EQ(ctx.tick, 1);
+}
+
+VF_TEST(theTraceRecordsEveryNodeVisitedInOrder) {
+    auto root = std::unique_ptr<SequenceNode>(new SequenceNode("root"));
+    root->add(constantAction("first", BehaviorStatus::Success, nullptr));
+    root->add(constantAction("second", BehaviorStatus::Failure, nullptr));
+    root->add(constantAction("third", BehaviorStatus::Success, nullptr));
+
+    BehaviorTree tree(std::move(root));
+    BehaviorContext ctx;
+    ctx.traceEnabled = true;
+    tree.tick(ctx);
+
+    std::vector<std::string> expected{"root", "first", "second"};
+    CHECK_EQ(ctx.trace.size(), expected.size());
+    for (std::size_t i = 0; i < expected.size() && i < ctx.trace.size(); ++i) {
+        CHECK_EQ(ctx.trace[i], expected[i]);
+    }
+}
+
+VF_TEST(theHostileTreePathsToThePlayerAndLandsRepeatedBlows) {
+    World world = flatWorld();
+    BehaviorAgent agent = makeAgent(Species::Zombie, {2.5f, 1.0f, 2.5f});
+
+    BehaviorContext ctx = freshContext(&world);
+    ctx.agent = &agent;
+    ctx.playerPresent = true;
+    ctx.playerPosition = {10.5f, 1.0f, 2.5f};
+
+    BehaviorTree tree = makeHostileHunterTree();
+    CHECK(tree.structureValid());
+
+    float startDistance = behaviorHorizontalDistance(agent.position, ctx.playerPosition);
+    for (int step = 0; step < 120; ++step) tree.tick(ctx);
+
+    CHECK(behaviorHorizontalDistance(agent.position, ctx.playerPosition) < startDistance);
+    CHECK(behaviorHorizontalDistance(agent.position, ctx.playerPosition) <=
+          speciesStats(Species::Zombie).attackRange);
+    CHECK(agent.attacksLanded >= 2);
+    CHECK(ctx.blackboard.flag("engaged"));
+    CHECK_NEAR(ctx.blackboard.number("lastAttackDamage"),
+               speciesStats(Species::Zombie).attackDamage, 1e-6f);
+    CHECK(agent.routeGoal == behaviorCellOf(ctx.playerPosition));
+    CHECK(agent.routePlannedTick > 0);
+}
+
+VF_TEST(theHostileTreeWalksHomeOnceTheTargetIsGone) {
+    World world = flatWorld();
+    BehaviorAgent agent = makeAgent(Species::Zombie, {9.5f, 1.0f, 2.5f});
+    agent.homePosition = {2.5f, 1.0f, 2.5f};
+
+    BehaviorContext ctx = freshContext(&world);
+    ctx.agent = &agent;
+    ctx.playerPresent = false;
+
+    BehaviorTree tree = makeHostileHunterTree();
+    for (int step = 0; step < 120; ++step) tree.tick(ctx);
+
+    CHECK(behaviorHorizontalDistance(agent.position, agent.homePosition) <=
+          ctx.tuning.homeReturnRadius);
+    CHECK_EQ(agent.attacksLanded, 0);
+}
+
+VF_TEST(theAnimalTreeRunsAwayFromAnEmptyHandedPlayer) {
+    World world = grassWorld();
+    BehaviorAgent agent = makeAgent(Species::Sheep, {0.5f, 1.0f, 0.5f});
+
+    BehaviorContext ctx = freshContext(&world);
+    ctx.agent = &agent;
+    ctx.playerPresent = true;
+    ctx.playerPosition = {2.5f, 1.0f, 0.5f};
+    ctx.playerHeldItem = ItemId::None;
+
+    BehaviorTree tree = makeGrazingAnimalTree();
+    float before = behaviorHorizontalDistance(agent.position, ctx.playerPosition);
+    for (int step = 0; step < 20; ++step) tree.tick(ctx);
+
+    CHECK(behaviorHorizontalDistance(agent.position, ctx.playerPosition) > before + 2.0f);
+    CHECK_EQ(agent.breedCount, 0);
+}
+
+VF_TEST(theAnimalTreeFollowsHeldFoodAndBreedsOnlyOncePerCooldown) {
+    World world = grassWorld();
+    BehaviorAgent agent = makeAgent(Species::Sheep, {0.5f, 1.0f, 0.5f});
+
+    BehaviorContext ctx = freshContext(&world);
+    ctx.agent = &agent;
+    ctx.playerPresent = true;
+    ctx.playerPosition = {6.5f, 1.0f, 0.5f};
+    ctx.playerHeldItem = breedingFoodFor(Species::Sheep);
+    ctx.matePresent = true;
+    ctx.matePosition = {5.0f, 1.0f, 0.5f};
+
+    BehaviorTree tree = makeGrazingAnimalTree();
+
+    std::vector<long long> breedTicks;
+    int lastCount = 0;
+    for (int step = 0; step < 400; ++step) {
+        tree.tick(ctx);
+        if (agent.breedCount != lastCount) {
+            lastCount = agent.breedCount;
+            breedTicks.push_back(ctx.tick);
+        }
+    }
+