diff --git a/tests/test_execute_recipe.py b/tests/test_execute_recipe.py
index bd3ae1d..647192b 100644
--- a/tests/test_execute_recipe.py
+++ b/tests/test_execute_recipe.py
@@ -244,3 +244,174 @@ class TestExecuteRecipeIntegration:
         # User source resolves from input_hashes
         user_cid = resolve_source_cid(user_source.config, input_hashes)
         assert user_cid == "QmUserProvidedVideo456"
+
+
+class TestCompoundNodeHandling:
+    """
+    Tests for COMPOUND node handling.
+
+    COMPOUND nodes are collapsed effect chains that should be executed
+    sequentially through their respective effect executors.
+
+    Bug fixed: "No executor for node type: COMPOUND"
+    """
+
+    def test_compound_node_has_filter_chain(self):
+        """COMPOUND nodes must have a filter_chain config."""
+        step = MockStep(
+            step_id="compound_1",
+            node_type="COMPOUND",
+            config={
+                "filter_chain": [
+                    {"type": "EFFECT", "config": {"effect": "identity"}},
+                    {"type": "EFFECT", "config": {"effect": "dog"}},
+                ],
+                "inputs": ["source_1"],
+            },
+            cache_id="compound_cache",
+            level=1,
+        )
+
+        assert step.node_type == "COMPOUND"
+        assert "filter_chain" in step.config
+        assert len(step.config["filter_chain"]) == 2
+
+    def test_compound_filter_chain_has_effects(self):
+        """COMPOUND filter_chain should contain EFFECT items with effect names."""
+        filter_chain = [
+            {"type": "EFFECT", "config": {"effect": "identity", "cid": "Qm123"}},
+            {"type": "EFFECT", "config": {"effect": "dog", "cid": "Qm456"}},
+        ]
+
+        for item in filter_chain:
+            assert item["type"] == "EFFECT"
+            assert "effect" in item["config"]
+            assert "cid" in item["config"]
+
+    def test_compound_requires_inputs(self):
+        """COMPOUND nodes must have input steps."""
+        step = MockStep(
+            step_id="compound_1",
+            node_type="COMPOUND",
+            config={"filter_chain": [], "inputs": []},
+            cache_id="compound_cache",
+            input_steps=[],
+            level=1,
+        )
+
+        # Empty inputs should be detected as error
+        assert len(step.input_steps) == 0
+        # The execute_recipe should raise ValueError for empty inputs
+
+
+class TestCacheIdLookup:
+    """
+    Tests for cache lookup by code-addressed cache_id.
+
+    Bug fixed: Cache lookups by cache_id (code hash) were failing because
+    only IPFS CID was indexed. Now we also index by node_id when different.
+    """
+
+    def test_cache_id_is_code_addressed(self):
+        """cache_id should be a SHA3-256 hash (64 hex chars), not IPFS CID."""
+        # Code-addressed hash example
+        cache_id = "5702aaec14adaddda9baefa94d5842143749ee19e6bb7c1fa7068dce21f51ed4"
+
+        assert len(cache_id) == 64
+        assert all(c in "0123456789abcdef" for c in cache_id)
+        assert not cache_id.startswith("Qm")  # Not IPFS CID
+
+    def test_ipfs_cid_format(self):
+        """IPFS CIDs start with 'Qm' (v0) or 'bafy' (v1)."""
+        ipfs_cid_v0 = "QmXrj6tSSn1vQXxxEY2Tyoudvt4CeeqR9gGQwSt7WFrhMZ"
+        ipfs_cid_v1 = "bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi"
+
+        assert ipfs_cid_v0.startswith("Qm")
+        assert ipfs_cid_v1.startswith("bafy")
+
+    def test_cache_id_differs_from_ipfs_cid(self):
+        """
+        Code-addressed cache_id is computed BEFORE execution.
+        IPFS CID is computed AFTER execution from file content.
+        They will differ for the same logical step.
+        """
+        # Same step can have:
+        cache_id = "5702aaec14adaddda9baefa94d5842143749ee19e6bb7c1fa7068dce21f51ed4"
+        ipfs_cid = "QmXrj6tSSn1vQXxxEY2Tyoudvt4CeeqR9gGQwSt7WFrhMZ"
+
+        assert cache_id != ipfs_cid
+        # Both should be indexable for cache lookups
+
+
+class TestPlanStepTypes:
+    """
+    Tests verifying all node types in S-expression plans are handled.
+
+    These tests document the node types that execute_recipe must handle.
+    """
+
+    def test_source_node_types(self):
+        """SOURCE nodes: fixed asset or user input."""
+        # Fixed asset source
+        fixed = MockStep("s1", "SOURCE", {"cid": "Qm123"}, "cache1")
+        assert fixed.node_type == "SOURCE"
+        assert "cid" in fixed.config
+
+        # User input source
+        user = MockStep("s2", "SOURCE", {"input": True, "name": "video"}, "cache2")
+        assert user.node_type == "SOURCE"
+        assert user.config.get("input") is True
+
+    def test_effect_node_type(self):
+        """EFFECT nodes: single effect application."""
+        step = MockStep(
+            "e1", "EFFECT",
+            {"effect": "invert", "cid": "QmEffect123", "intensity": 1.0},
+            "cache3"
+        )
+        assert step.node_type == "EFFECT"
+        assert "effect" in step.config
+
+    def test_compound_node_type(self):
+        """COMPOUND nodes: collapsed effect chains."""
+        step = MockStep(
+            "c1", "COMPOUND",
+            {"filter_chain": [{"type": "EFFECT", "config": {}}]},
+            "cache4"
+        )
+        assert step.node_type == "COMPOUND"
+        assert "filter_chain" in step.config
+
+    def test_sequence_node_type(self):
+        """SEQUENCE nodes: concatenate multiple clips."""
+        step = MockStep(
+            "seq1", "SEQUENCE",
+            {"transition": {"type": "cut"}},
+            "cache5",
+            input_steps=["clip1", "clip2"]
+        )
+        assert step.node_type == "SEQUENCE"
+
+
+class TestExecuteRecipeErrorHandling:
+    """Tests for error handling in execute_recipe."""
+
+    def test_missing_input_hash_error_message(self):
+        """Error should list available input keys when source not found."""
+        config = {"input": True, "name": "Unknown Video"}
+        input_hashes = {"video-a": "Qm1", "video-b": "Qm2"}
+
+        with pytest.raises(ValueError) as excinfo:
+            resolve_source_cid(config, input_hashes)
+
+        error_msg = str(excinfo.value)
+        assert "Unknown Video" in error_msg
+        assert "video-a" in error_msg or "video-b" in error_msg
+
+    def test_source_no_cid_no_input_error(self):
+        """SOURCE without cid or input flag should return None (invalid)."""
+        config = {"name": "broken-source"}  # Missing both cid and input
+        input_hashes = {}
+
+        result = resolve_source_cid(config, input_hashes)
+        assert result is None  # execute_recipe should catch this