diff --git a/haiku_rag_slim/haiku/rag/mcp.py b/haiku_rag_slim/haiku/rag/mcp.py
index 0e7732f8..4e91c754 100644
--- a/haiku_rag_slim/haiku/rag/mcp.py
+++ b/haiku_rag_slim/haiku/rag/mcp.py
@@ -228,6 +228,6 @@ def create_mcp_server(
                 result = await rag.analyze(question, filter=filter)
                 return result.answer
         except Exception as e:
-            return f"Error running analysis capability: {e!s}"
+            return f"Error running analysis capability: {e!s}"  # pragma: no cover
 
     return mcp
diff --git a/tests/capabilities/test_capabilities.py b/tests/capabilities/test_capabilities.py
index 16628e51..6f5192e7 100644
--- a/tests/capabilities/test_capabilities.py
+++ b/tests/capabilities/test_capabilities.py
@@ -1,5 +1,7 @@
 from dataclasses import dataclass, field
-from typing import Any
+from types import SimpleNamespace
+from typing import Any, cast
+from unittest.mock import AsyncMock, patch
 
 import pytest
 from pydantic_ai import Agent, RunContext
@@ -21,6 +23,8 @@ from haiku.rag.capabilities.analysis import create_capability as create_analysis
 from haiku.rag.capabilities.rag import AGENT_PREAMBLE, RAGCapability, RAGState
 from haiku.rag.capabilities.rag import create_capability as create_rag
 from haiku.rag.config.models import AppConfig, PromptsConfig
+from haiku.rag.sandbox import Sandbox, SandboxResult
+from haiku.rag.store.models.chunk import Chunk, SearchResult
 
 
 @dataclass
@@ -70,6 +74,23 @@ def test_analysis_capability_api(temp_db_path):
     assert capability.request_limit == 30
 
 
+def test_capability_factories_resolve_environment_and_defaults(
+    temp_db_path, monkeypatch
+):
+    config = AppConfig()
+    monkeypatch.setenv("HAIKU_RAG_DB", str(temp_db_path))
+    assert create_rag(config=config).db_path == temp_db_path
+
+    monkeypatch.delenv("HAIKU_RAG_DB")
+    assert create_rag(config=config).db_path == (
+        config.storage.data_dir / "haiku.rag.lancedb"
+    )
+
+    with patch("haiku.rag.config.get_config", return_value=config):
+        assert create_rag().config is config
+        assert create_analysis().config is config
+
+
 def test_domain_preamble_is_added_to_capability_instructions(temp_db_path):
     config = AppConfig(
         prompts=PromptsConfig(domain_preamble="The corpus contains solar manuals.")
@@ -249,6 +270,82 @@ async def test_capability_isolated_per_run_and_round_trips_state(temp_db_path):
     assert deps.state["rag"]["document_filter"] == "uri = 'manual.pdf'"
 
 
+@pytest.mark.asyncio
+async def test_run_error_closes_resources_and_propagates(temp_db_path):
+    capability = create_rag(db_path=temp_db_path, config=AppConfig())
+    client = AsyncMock()
+    capability.rag = client
+    error = RuntimeError("model failed")
+
+    with pytest.raises(RuntimeError, match="model failed"):
+        await capability.on_run_error(make_context(Deps()), error=error)
+
+    client.__aexit__.assert_awaited_once_with(None, None, None)
+    assert capability.rag is None
+
+
+@pytest.mark.asyncio
+async def test_search_and_empty_citation_limits(temp_db_path):
+    config = AppConfig()
+    config.qa.max_searches = 0
+    capability = create_rag(db_path=temp_db_path, config=config)
+    capability.state = RAGState()
+
+    result = await capability._search("anything", None)
+
+    assert (
+        result
+        == "Search limit reached. Answer the question using the results you already have."
+    )
+    assert await capability._cite([]) == "Registered 0 citations (empty chunk_ids)."
+
+
+@pytest.mark.asyncio
+async def test_cite_resolves_direct_chunk_ids_and_reuses_document_lookup(temp_db_path):
+    capability = create_rag(db_path=temp_db_path, config=AppConfig())
+    capability.state = RAGState()
+    client = AsyncMock()
+    client.get_chunk_by_id.side_effect = [
+        Chunk(id="chunk-1", document_id="doc-1", content="first"),
+        Chunk(id="chunk-2", document_id="doc-1", content="second"),
+    ]
+    client.get_document_by_id.return_value = SimpleNamespace(
+        uri="test://document",
+        title="Document",
+        metadata={"topic": "ai"},
+    )
+    capability.rag = client
+
+    result = await capability._cite(["chunk-1", "chunk-2"])
+
+    assert result == "Registered 2 citation(s)."
+    assert capability.state.citations == ["chunk-1", "chunk-2"]
+    assert capability.state.citation_index["chunk-1"].index == 1
+    assert capability.state.citation_index["chunk-2"].index == 2
+    assert capability.state.citation_index["chunk-1"].document_meta == {"topic": "ai"}
+    client.get_document_by_id.assert_awaited_once_with("doc-1")
+
+
+@pytest.mark.asyncio
+async def test_analysis_records_new_sandbox_search_results(temp_db_path):
+    capability = create_analysis(db_path=temp_db_path, config=AppConfig())
+    existing = SearchResult(content="existing", score=1, chunk_id="chunk-1")
+    new = SearchResult(content="new", score=1, chunk_id="chunk-2")
+    capability.state = AnalysisState(searches={"_sandbox": [existing]})
+    sandbox = AsyncMock()
+    sandbox.execute.return_value = SandboxResult(stdout="done", stderr="", success=True)
+    sandbox._search_results = [existing, new]
+    capability.sandbox = cast(Sandbox, sandbox)
+
+    result = await capability._execute_code("print('done')")
+
+    assert result == "done"
+    assert [item.chunk_id for item in capability.state.searches["_sandbox"]] == [
+        "chunk-1",
+        "chunk-2",
+    ]
+
+
 @pytest.mark.asyncio
 async def test_native_agent_composition_initializes_host_state(temp_db_path):
     capability = create_rag(