test: add unit tests for 8 modules (batch 2)

Cover model_tools, toolset_distributions, context_compressor,
prompt_caching, cronjob_tools, session_search, process_registry,
and cron/scheduler with 127 new test cases.

tests/test_toolset_distributions.py

@@ -0,0 +1,103 @@
+"""Tests for toolset_distributions.py — distribution CRUD, sampling, validation."""
+
+import pytest
+from unittest.mock import patch
+
+from toolset_distributions import (
+    DISTRIBUTIONS,
+    get_distribution,
+    list_distributions,
+    sample_toolsets_from_distribution,
+    validate_distribution,
+)
+
+
+class TestGetDistribution:
+    def test_known_distribution(self):
+        dist = get_distribution("default")
+        assert dist is not None
+        assert "description" in dist
+        assert "toolsets" in dist
+
+    def test_unknown_returns_none(self):
+        assert get_distribution("nonexistent") is None
+
+    def test_all_named_distributions_exist(self):
+        expected = [
+            "default", "image_gen", "research", "science", "development",
+            "safe", "balanced", "minimal", "terminal_only", "terminal_web",
+            "creative", "reasoning", "browser_use", "browser_only",
+            "browser_tasks", "terminal_tasks", "mixed_tasks",
+        ]
+        for name in expected:
+            assert get_distribution(name) is not None, f"{name} missing"
+
+
+class TestListDistributions:
+    def test_returns_copy(self):
+        d1 = list_distributions()
+        d2 = list_distributions()
+        assert d1 is not d2
+        assert d1 == d2
+
+    def test_contains_all(self):
+        dists = list_distributions()
+        assert len(dists) == len(DISTRIBUTIONS)
+
+
+class TestValidateDistribution:
+    def test_valid(self):
+        assert validate_distribution("default") is True
+        assert validate_distribution("research") is True
+
+    def test_invalid(self):
+        assert validate_distribution("nonexistent") is False
+        assert validate_distribution("") is False
+
+
+class TestSampleToolsetsFromDistribution:
+    def test_unknown_raises(self):
+        with pytest.raises(ValueError, match="Unknown distribution"):
+            sample_toolsets_from_distribution("nonexistent")
+
+    def test_default_returns_all_toolsets(self):
+        # default has all at 100%, so all should be selected
+        result = sample_toolsets_from_distribution("default")
+        assert len(result) > 0
+        # With 100% probability, all valid toolsets should be present
+        dist = get_distribution("default")
+        for ts in dist["toolsets"]:
+            assert ts in result
+
+    def test_minimal_returns_web_only(self):
+        result = sample_toolsets_from_distribution("minimal")
+        assert "web" in result
+
+    def test_returns_list_of_strings(self):
+        result = sample_toolsets_from_distribution("balanced")
+        assert isinstance(result, list)
+        for item in result:
+            assert isinstance(item, str)
+
+    def test_fallback_guarantees_at_least_one(self):
+        # Even with low probabilities, at least one toolset should be selected
+        for _ in range(20):
+            result = sample_toolsets_from_distribution("reasoning")
+            assert len(result) >= 1
+
+
+class TestDistributionStructure:
+    def test_all_have_required_keys(self):
+        for name, dist in DISTRIBUTIONS.items():
+            assert "description" in dist, f"{name} missing description"
+            assert "toolsets" in dist, f"{name} missing toolsets"
+            assert isinstance(dist["toolsets"], dict), f"{name} toolsets not a dict"
+
+    def test_probabilities_are_valid_range(self):
+        for name, dist in DISTRIBUTIONS.items():
+            for ts_name, prob in dist["toolsets"].items():
+                assert 0 < prob <= 100, f"{name}.{ts_name} has invalid probability {prob}"
+
+    def test_descriptions_non_empty(self):
+        for name, dist in DISTRIBUTIONS.items():
+            assert len(dist["description"]) > 5, f"{name} has too short description"