Fix elicitation graceful degradation when client lacks protocol support

ctx.elicit() throws an exception (not CancelledElicitation) when the
MCP client doesn't implement the elicitation/create JSON-RPC method.
Wrap the call in try/except to treat protocol-level rejection the
same as CancelledElicitation. Found during live testing with Claude
Code CLI which doesn't support MCP elicitation yet.

src/mcdbus/_interaction.py

@@ -25,13 +25,19 @@ from mcdbus._state import mcp
 
 async def _confirm_or_abort(ctx: Context, message: str, operation: str) -> None:
     """Elicit user confirmation; raise ToolError or return silently to proceed."""
-    result = await ctx.elicit(
-        message,
-        {
-            "confirm": {"title": "Yes, proceed"},
-            "deny": {"title": "No, cancel"},
-        },
-    )
+    try:
+        result = await ctx.elicit(
+            message,
+            {
+                "confirm": {"title": "Yes, proceed"},
+                "deny": {"title": "No, cancel"},
+            },
+        )
+    except Exception:
+        # Client doesn't implement elicitation at the protocol level —
+        # ctx.elicit() throws instead of returning CancelledElicitation.
+        result = CancelledElicitation()
+
     if isinstance(result, AcceptedElicitation) and result.data == "confirm":
         return
     if isinstance(result, CancelledElicitation):

tests/test_elicitation.py

@@ -48,6 +48,21 @@ class TestConfirmOrAbort:
             with pytest.raises(ToolError, match="Elicitation required"):
                 await _confirm_or_abort(ctx, "Test message", "test_op")
 
+    async def test_elicit_exception_treated_as_cancelled(self):
+        """When ctx.elicit() throws (client lacks protocol support), proceed."""
+        ctx = AsyncMock()
+        ctx.elicit = AsyncMock(side_effect=Exception("Method not found"))
+        # Should not raise — exception is treated as CancelledElicitation
+        await _confirm_or_abort(ctx, "Test message", "test_op")
+
+    async def test_elicit_exception_hard_fails_when_required(self):
+        """When ctx.elicit() throws and MCDBUS_REQUIRE_ELICITATION is set, fail."""
+        ctx = AsyncMock()
+        ctx.elicit = AsyncMock(side_effect=Exception("Method not found"))
+        with patch.dict(os.environ, {"MCDBUS_REQUIRE_ELICITATION": "1"}):
+            with pytest.raises(ToolError, match="Elicitation required"):
+                await _confirm_or_abort(ctx, "Test message", "test_op")
+
 
 class TestCallMethodElicitation:
     """Verify call_method triggers elicitation on system bus but not session bus."""