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/agent/test_prompt_caching.py

@@ -0,0 +1,128 @@
+"""Tests for agent/prompt_caching.py — Anthropic cache control injection."""
+
+import copy
+import pytest
+
+from agent.prompt_caching import (
+    _apply_cache_marker,
+    apply_anthropic_cache_control,
+)
+
+
+MARKER = {"type": "ephemeral"}
+
+
+class TestApplyCacheMarker:
+    def test_tool_message_gets_top_level_marker(self):
+        msg = {"role": "tool", "content": "result"}
+        _apply_cache_marker(msg, MARKER)
+        assert msg["cache_control"] == MARKER
+
+    def test_none_content_gets_top_level_marker(self):
+        msg = {"role": "assistant", "content": None}
+        _apply_cache_marker(msg, MARKER)
+        assert msg["cache_control"] == MARKER
+
+    def test_string_content_wrapped_in_list(self):
+        msg = {"role": "user", "content": "Hello"}
+        _apply_cache_marker(msg, MARKER)
+        assert isinstance(msg["content"], list)
+        assert len(msg["content"]) == 1
+        assert msg["content"][0]["type"] == "text"
+        assert msg["content"][0]["text"] == "Hello"
+        assert msg["content"][0]["cache_control"] == MARKER
+
+    def test_list_content_last_item_gets_marker(self):
+        msg = {
+            "role": "user",
+            "content": [
+                {"type": "text", "text": "First"},
+                {"type": "text", "text": "Second"},
+            ],
+        }
+        _apply_cache_marker(msg, MARKER)
+        assert "cache_control" not in msg["content"][0]
+        assert msg["content"][1]["cache_control"] == MARKER
+
+    def test_empty_list_content_no_crash(self):
+        msg = {"role": "user", "content": []}
+        # Should not crash on empty list
+        _apply_cache_marker(msg, MARKER)
+
+
+class TestApplyAnthropicCacheControl:
+    def test_empty_messages(self):
+        result = apply_anthropic_cache_control([])
+        assert result == []
+
+    def test_returns_deep_copy(self):
+        msgs = [{"role": "user", "content": "Hello"}]
+        result = apply_anthropic_cache_control(msgs)
+        assert result is not msgs
+        assert result[0] is not msgs[0]
+        # Original should be unmodified
+        assert "cache_control" not in msgs[0].get("content", "")
+
+    def test_system_message_gets_marker(self):
+        msgs = [
+            {"role": "system", "content": "You are helpful"},
+            {"role": "user", "content": "Hi"},
+        ]
+        result = apply_anthropic_cache_control(msgs)
+        # System message should have cache_control
+        sys_content = result[0]["content"]
+        assert isinstance(sys_content, list)
+        assert sys_content[0]["cache_control"]["type"] == "ephemeral"
+
+    def test_last_3_non_system_get_markers(self):
+        msgs = [
+            {"role": "system", "content": "System"},
+            {"role": "user", "content": "msg1"},
+            {"role": "assistant", "content": "msg2"},
+            {"role": "user", "content": "msg3"},
+            {"role": "assistant", "content": "msg4"},
+        ]
+        result = apply_anthropic_cache_control(msgs)
+        # System (index 0) + last 3 non-system (indices 2, 3, 4) = 4 breakpoints
+        # Index 1 (msg1) should NOT have marker
+        content_1 = result[1]["content"]
+        if isinstance(content_1, str):
+            assert True  # No marker applied (still a string)
+        else:
+            assert "cache_control" not in content_1[0]
+
+    def test_no_system_message(self):
+        msgs = [
+            {"role": "user", "content": "Hello"},
+            {"role": "assistant", "content": "Hi"},
+        ]
+        result = apply_anthropic_cache_control(msgs)
+        # Both should get markers (4 slots available, only 2 messages)
+        assert len(result) == 2
+
+    def test_1h_ttl(self):
+        msgs = [{"role": "system", "content": "System prompt"}]
+        result = apply_anthropic_cache_control(msgs, cache_ttl="1h")
+        sys_content = result[0]["content"]
+        assert isinstance(sys_content, list)
+        assert sys_content[0]["cache_control"]["ttl"] == "1h"
+
+    def test_max_4_breakpoints(self):
+        msgs = [
+            {"role": "system", "content": "System"},
+        ] + [
+            {"role": "user" if i % 2 == 0 else "assistant", "content": f"msg{i}"}
+            for i in range(10)
+        ]
+        result = apply_anthropic_cache_control(msgs)
+        # Count how many messages have cache_control
+        count = 0
+        for msg in result:
+            content = msg.get("content")
+            if isinstance(content, list):
+                for item in content:
+                    if isinstance(item, dict) and "cache_control" in item:
+                        count += 1
+            elif "cache_control" in msg:
+                count += 1
+        assert count <= 4