fix(tests): add missing comprehensive test files and fix gitignore

The comprehensive test files were not committed due to .gitignore pattern 'test_*.py' blocking all test files. Fixed gitignore to only exclude root-level test scripts.

code/tests/test_random_determinism_comprehensive.py

@@ -0,0 +1,122 @@
+"""
+Comprehensive tests for Random Build determinism and seed stability.
+
+Consolidates:
+- test_random_determinism.py (Basic determinism)
+- test_random_determinism_delta.py (Delta checking)
+- test_random_full_build_determinism.py (Full build determinism)
+- test_random_multi_theme_seed_stability.py (Multi-theme stability)
+"""
+from __future__ import annotations
+
+import os
+from deck_builder.random_entrypoint import build_random_deck
+
+
+# ============================================================================
+# Basic Determinism Tests
+# ============================================================================
+
+def test_random_build_is_deterministic_with_seed(monkeypatch):
+    """Fixed seed produces identical commander consistently."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    out1 = build_random_deck(seed=12345)
+    out2 = build_random_deck(seed=12345)
+    
+    assert out1.commander == out2.commander
+    assert out1.seed == out2.seed
+
+
+def test_random_build_uses_theme_when_available(monkeypatch):
+    """Theme parameter is accepted and produces valid output."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    res = build_random_deck(theme="Goblin Kindred", seed=42)
+    assert isinstance(res.commander, str) and len(res.commander) > 0
+
+
+def test_different_seeds_produce_different_commanders(monkeypatch):
+    """Different seeds should produce different results (probabilistic)."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    out1 = build_random_deck(seed=1)
+    out2 = build_random_deck(seed=2)
+    out3 = build_random_deck(seed=3)
+    
+    # At least one should be different (very likely with different seeds)
+    commanders = {out1.commander, out2.commander, out3.commander}
+    assert len(commanders) >= 2, "Different seeds should produce varied results"
+
+
+# ============================================================================
+# Delta Checking Tests
+# ============================================================================
+
+def test_random_build_delta_consistency(monkeypatch):
+    """Small seed delta produces different but consistent results."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    # Build with seed N and seed N+1
+    out1 = build_random_deck(seed=5000)
+    out2 = build_random_deck(seed=5001)
+    
+    # Results should be reproducible
+    out1_repeat = build_random_deck(seed=5000)
+    out2_repeat = build_random_deck(seed=5001)
+    
+    assert out1.commander == out1_repeat.commander
+    assert out2.commander == out2_repeat.commander
+
+
+# ============================================================================
+# Multi-Theme Seed Stability Tests
+# ============================================================================
+
+def test_random_build_multi_theme_stability(monkeypatch):
+    """Multiple themes with same seed produce consistent results."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    # Try with multiple themes (if supported)
+    out1 = build_random_deck(
+        theme="Goblin Kindred",
+        secondary_theme="Aggro",
+        seed=999
+    )
+    out2 = build_random_deck(
+        theme="Goblin Kindred",
+        secondary_theme="Aggro",
+        seed=999
+    )
+    
+    assert out1.commander == out2.commander
+    assert out1.seed == out2.seed
+
+
+def test_random_build_multi_theme_different_order(monkeypatch):
+    """Theme order shouldn't break determinism (if themes are sorted internally)."""
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    
+    # Build with themes in different order but same seed
+    out1 = build_random_deck(
+        theme="Goblin Kindred",
+        secondary_theme="Aggro",
+        seed=1111
+    )
+    out2 = build_random_deck(
+        theme="Aggro",
+        secondary_theme="Goblin Kindred",
+        seed=1111
+    )
+    
+    # Both should succeed and be reproducible
+    assert out1.commander
+    assert out2.commander
+    
+    # Verify reproducibility for each configuration
+    out1_repeat = build_random_deck(
+        theme="Goblin Kindred",
+        secondary_theme="Aggro",
+        seed=1111
+    )
+    assert out1.commander == out1_repeat.commander