test: reorganize test structure and add missing unit tests

Reorganize flat tests/ directory to mirror source code structure
(tools/, gateway/, hermes_cli/, integration/). Add 11 new test files
covering previously untested modules: registry, patch_parser,
fuzzy_match, todo_tool, approval, file_tools, gateway session/config/
delivery, and hermes_cli config/models. Total: 147 unit tests passing,
9 integration tests gated behind pytest marker.

tests/tools/test_registry.py

@@ -0,0 +1,121 @@
+"""Tests for the central tool registry."""
+
+import json
+
+from tools.registry import ToolRegistry
+
+
+def _dummy_handler(args, **kwargs):
+    return json.dumps({"ok": True})
+
+
+def _make_schema(name="test_tool"):
+    return {"name": name, "description": f"A {name}", "parameters": {"type": "object", "properties": {}}}
+
+
+class TestRegisterAndDispatch:
+    def test_register_and_dispatch(self):
+        reg = ToolRegistry()
+        reg.register(
+            name="alpha",
+            toolset="core",
+            schema=_make_schema("alpha"),
+            handler=_dummy_handler,
+        )
+        result = json.loads(reg.dispatch("alpha", {}))
+        assert result == {"ok": True}
+
+    def test_dispatch_passes_args(self):
+        reg = ToolRegistry()
+
+        def echo_handler(args, **kw):
+            return json.dumps(args)
+
+        reg.register(name="echo", toolset="core", schema=_make_schema("echo"), handler=echo_handler)
+        result = json.loads(reg.dispatch("echo", {"msg": "hi"}))
+        assert result == {"msg": "hi"}
+
+
+class TestGetDefinitions:
+    def test_returns_openai_format(self):
+        reg = ToolRegistry()
+        reg.register(name="t1", toolset="s1", schema=_make_schema("t1"), handler=_dummy_handler)
+        reg.register(name="t2", toolset="s1", schema=_make_schema("t2"), handler=_dummy_handler)
+
+        defs = reg.get_definitions({"t1", "t2"})
+        assert len(defs) == 2
+        assert all(d["type"] == "function" for d in defs)
+        names = {d["function"]["name"] for d in defs}
+        assert names == {"t1", "t2"}
+
+    def test_skips_unavailable_tools(self):
+        reg = ToolRegistry()
+        reg.register(
+            name="available",
+            toolset="s",
+            schema=_make_schema("available"),
+            handler=_dummy_handler,
+            check_fn=lambda: True,
+        )
+        reg.register(
+            name="unavailable",
+            toolset="s",
+            schema=_make_schema("unavailable"),
+            handler=_dummy_handler,
+            check_fn=lambda: False,
+        )
+        defs = reg.get_definitions({"available", "unavailable"})
+        assert len(defs) == 1
+        assert defs[0]["function"]["name"] == "available"
+
+
+class TestUnknownToolDispatch:
+    def test_returns_error_json(self):
+        reg = ToolRegistry()
+        result = json.loads(reg.dispatch("nonexistent", {}))
+        assert "error" in result
+        assert "Unknown tool" in result["error"]
+
+
+class TestToolsetAvailability:
+    def test_no_check_fn_is_available(self):
+        reg = ToolRegistry()
+        reg.register(name="t", toolset="free", schema=_make_schema(), handler=_dummy_handler)
+        assert reg.is_toolset_available("free") is True
+
+    def test_check_fn_controls_availability(self):
+        reg = ToolRegistry()
+        reg.register(
+            name="t",
+            toolset="locked",
+            schema=_make_schema(),
+            handler=_dummy_handler,
+            check_fn=lambda: False,
+        )
+        assert reg.is_toolset_available("locked") is False
+
+    def test_check_toolset_requirements(self):
+        reg = ToolRegistry()
+        reg.register(name="a", toolset="ok", schema=_make_schema(), handler=_dummy_handler, check_fn=lambda: True)
+        reg.register(name="b", toolset="nope", schema=_make_schema(), handler=_dummy_handler, check_fn=lambda: False)
+
+        reqs = reg.check_toolset_requirements()
+        assert reqs["ok"] is True
+        assert reqs["nope"] is False
+
+    def test_get_all_tool_names(self):
+        reg = ToolRegistry()
+        reg.register(name="z_tool", toolset="s", schema=_make_schema(), handler=_dummy_handler)
+        reg.register(name="a_tool", toolset="s", schema=_make_schema(), handler=_dummy_handler)
+        assert reg.get_all_tool_names() == ["a_tool", "z_tool"]
+
+    def test_handler_exception_returns_error(self):
+        reg = ToolRegistry()
+
+        def bad_handler(args, **kw):
+            raise RuntimeError("boom")
+
+        reg.register(name="bad", toolset="s", schema=_make_schema(), handler=bad_handler)
+        result = json.loads(reg.dispatch("bad", {}))
+        assert "error" in result
+        assert "RuntimeError" in result["error"]