AG-UI ADK is not cleaning pending tools

[rrazvd]

I have been trying to implement a chat just using HttpAgent on React and I'm currently stuck on a problem that pending_tool_calls persists and don't get resolved.

I would like to confirm if I am implementing wrong or there is a bug that ADK Middleware doesn't clean pending tools properly. Here is my code.

As we can see below, there is in Messages State a message with the result of render_ItemsList tool. But when we look to the session registered on ADK Session DB, we cannot see the render_ItemsList tool result event. So, pending_tool_calls remains with the toolCallId.

HttpAgent Messages State:

[
    {
        "id": "user-1760622214456",
        "role": "user",
        "content": "Hi\n"
    },
    {
        "id": "76f84e95-595f-4a9a-971b-5d2b05ef1680",
        "role": "assistant",
        "content": "Hello Joe Doe! How can I help you today?"
    },
    {
        "id": "user-1760622234346",
        "role": "user",
        "content": "I would like to see the available items\n"
    },
    {
        "id": "adk-5ad444ed-0610-49ae-bf14-c89273b38d6f",
        "role": "assistant",
        "toolCalls": [
            {
                "id": "adk-5ad444ed-0610-49ae-bf14-c89273b38d6f",
                "type": "function",
                "function": {
                    "name": "get_items",
                    "arguments": ""
                }
            }
        ]
    },
    {
        "id": "ffa2d8c9-f1e8-4aed-97aa-56ee440c8404",
        "toolCallId": "adk-5ad444ed-0610-49ae-bf14-c89273b38d6f",
        "role": "tool",
        "content": "{\"result\": [\"Item 1\", \"Item 2\", \"Item 3\", \"Item 4\", \"Item 5\"]}"
    },
    {
        "id": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571", // render_ItemsList tool call
        "role": "assistant",
        "toolCalls": [
            {
                "id": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571",
                "type": "function",
                "function": {
                    "name": "render_ItemsList",
                    "arguments": "{\"items\": [\"Item 1\", \"Item 2\", \"Item 3\", \"Item 4\", \"Item 5\"]}"
                }
            }
        ]
    },
    {
        "id": "tool-result-1760622239565", // render_ItemsList tool result sent by client
        "role": "tool",
        "content": "{\"status\":\"success\",\"message\":\"Items were rendered successfully.\",\"itemsCount\":5}",
        "toolCallId": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571"
    },
    {
        "id": "user-1760622531664",
        "role": "user",
        "content": "Cool"
    }
]

Session registered on ADK db:

{
	"id": "ca4a6c6c-a554-442e-8b89-31a715f97d3c",
	"appName": "agent",
	"userId": "user-123",
	"state": {
		"user_id": "user-123",
		"user_name": "Joe Doe",
		"pending_tool_calls": [
			"adk-8ccd7b09-4c51-4352-be35-da49bc10a571" // toolCallId persists, we cannot see an event with this tool result
		]
	},
	"events": [
		{
			"invocationId": "state_update_1760622214",
			"author": "system",
			"actions": {
				"stateDelta": {
					"user_id": "user-123",
					"user_name": "Joe Doe"
				},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "5eecf8ef-7866-4fa7-ac90-f06474c5f8ec",
			"timestamp": 1760622214.65949
		},
		{
			"content": {
				"parts": [
					{
						"text": "Hi\n"
					}
				],
				"role": "user"
			},
			"invocationId": "e-7a649858-9b89-4878-9665-4f3d7ef583b3",
			"author": "user",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "ea6dab00-b584-4588-868d-953b2a8c8c76",
			"timestamp": 1760622214.672113
		},
		{
			"content": {
				"parts": [
					{
						"text": "Hello Joe Doe! How can I help you today?"
					}
				],
				"role": "model"
			},
			"invocationId": "e-7a649858-9b89-4878-9665-4f3d7ef583b3",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "18185c89-31ed-43e2-96c3-f11b9280bd5d",
			"timestamp": 1760622216.554769
		},
		{
			"invocationId": "state_update_1760622234",
			"author": "system",
			"actions": {
				"stateDelta": {
					"user_id": "user-123",
					"user_name": "Joe Doe"
				},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "421d663f-ee43-4d52-aa57-8f0dcdd3e9a2",
			"timestamp": 1760622234.422587
		},
		{
			"content": {
				"parts": [
					{
						"text": "I would like to see the available items\n"
					}
				],
				"role": "user"
			},
			"invocationId": "e-a1a8bf33-e77f-4e5a-b1a4-5f9c0170670b",
			"author": "user",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "e2e37bf4-52da-474c-83e1-4e6f36648f00",
			"timestamp": 1760622234.443018
		},
		{
			"content": {
				"parts": [
					{
						"thoughtSignature": "CikB0e2Kb0uzhedBITTDSdgQBX5okPM0bvKzDyVod2Cqc2A35hSpAy7GWwpkAdHtim9hELttZxq0fa7xctgyoMlQ9i0UOYHFfOWa_smKArp83DZGf1bF1Wyd-NEnCeJyc0IWmkOu2m22IxJIxuYnUGQMdKV7gN6oBtqJlbQhPc5gn61nj-rD0zi_b068y3or3wqdAQHR7Ypvz_op3P7LsqKLbqW9wW-IK14Wc6_Hk6c2nHmweHExvfjcdnSvCoZHMix33OMvn0s_j31omwWN-p2pamrautmnFvMAyJEZ-7p2ECMZUmx977JgBgQ4hJ1yxkKfsKF2L1fBPknLRlvl3mGVBJ7d0eRJkSfSE0BESpYV1AOB76ua0v1VlO-Ogiwtappg0bqXvwZ5ADxvQUEO7pM=",
						"functionCall": {
							"id": "adk-5ad444ed-0610-49ae-bf14-c89273b38d6f",
							"args": {},
							"name": "get_items"
						}
					}
				],
				"role": "model"
			},
			"invocationId": "e-a1a8bf33-e77f-4e5a-b1a4-5f9c0170670b",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "c4a7cd78-1216-4943-9f6f-fe201567b86d",
			"timestamp": 1760622234.448923
		},
		{
			"content": {
				"parts": [
					{
						"functionResponse": {
							"id": "adk-5ad444ed-0610-49ae-bf14-c89273b38d6f",
							"name": "get_items",
							"response": {
								"result": [
									"Item 1",
									"Item 2",
									"Item 3",
									"Item 4",
									"Item 5"
								]
							}
						}
					}
				],
				"role": "user"
			},
			"invocationId": "e-a1a8bf33-e77f-4e5a-b1a4-5f9c0170670b",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "5b0c0c96-02c8-4da2-8b21-34ea9eb7d545",
			"timestamp": 1760622236.385817
		},
		{
			"content": {
				"parts": [
					{
						"thoughtSignature": "CikB0e2Kb2NfqEJgBm9vvOQ5Ja09Q3ngf4ssQeF_jLykEOPIRahc6wcqVgpyAdHtim_r4n6-OVwJNul_fhd-oLoHyQT-x8v8Ge9JA2bk57ppk7b-2hmhIUg0lh4JkjWmZM61ldzyVIaQbut6UIz1K7t1oECAQHWpstCSVqpfiQuYxKUR45uE2aAoFJ50XRABk5J8P2xQbo2Sa1RsHhV2CqwBAdHtim96LzYVdxKGt_WJze89VrAkexAUL5YYaBIFHISfQf_T2kTgriMWgTbd2FBT1hrwxxgp7cLgwObJOHDS7cUYaalXineZyo0KnC1-yRSjeMgHY_QeZeDZT3jS-Wj7iN_-8QakEYIoh4XTbKTyaAKI0baeNgA2f_TY1mw2e1meqNsscOruNXst0g5RM4CM4IK14m6IWl7WZf68S3wFqWIF55NnfTCHjdOK4wolAdHtim-kjIOFEqpE2V0rkHlOpRZtGNNMv8MR77FmlLJbFy-h3A==",
						"functionCall": {
							"id": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571",
							"args": {
								"items": [
									"Item 1",
									"Item 2",
									"Item 3",
									"Item 4",
									"Item 5"
								]
							},
							"name": "render_ItemsList"
						}
					}
				],
				"role": "model"
			},
			"invocationId": "e-a1a8bf33-e77f-4e5a-b1a4-5f9c0170670b",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [
				"adk-8ccd7b09-4c51-4352-be35-da49bc10a571"
			],
			"id": "5718940c-2c2e-4a1c-95d5-60ed239a11c8",
			"timestamp": 1760622236.392789
		},
		{
			"invocationId": "state_update_1760622240",
			"author": "system",
			"actions": {
				"stateDelta": {
					"pending_tool_calls": [
						"adk-8ccd7b09-4c51-4352-be35-da49bc10a571"
					]
				},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "330711d9-a910-475a-ba45-457b593ac1a7",
			"timestamp": 1760622240.565043
		},
		{
			"invocationId": "state_update_1760622531",
			"author": "system",
			"actions": {
				"stateDelta": {
					"user_id": "user-123",
					"user_name": "Joe Doe"
				},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "14ff9f88-f93c-4fcb-9c9a-374771417a9d",
			"timestamp": 1760622531.760833
		},
		{
			"content": {
				"parts": [
					{
						"text": "Cool"
					}
				],
				"role": "user"
			},
			"invocationId": "e-7d2cfd01-dc2f-4b76-a344-522f61243311",
			"author": "user",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "8b7217c4-5a76-49e4-a76b-03f47ac310b5",
			"timestamp": 1760622531.776152
		},
		{
			"content": {
				"parts": [
					{
						"text": "Here are the available items for you to choose from. Is there anything else I can help you with?"
					}
				],
				"role": "model"
			},
			"invocationId": "e-7d2cfd01-dc2f-4b76-a344-522f61243311",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},
			"longRunningToolIds": [],
			"id": "718bea92-5902-42e1-9728-c9abcf2d5a34",
			"timestamp": 1760622534.456543
		}
	],
	"lastUpdateTime": 1760622531.0
}

[contextablemark]

@NathanTarbert You can assign to me to investigate

[NathanTarbert]

Amazing, thanks @contextablemark!

[trend-denny-lee]

@rrazvd
But I see render_ItemsList in the session you provided:

{
			"content": {
				"parts": [
					{
						"thoughtSignature": "CikB0e2Kb2NfqEJgBm9vvOQ5Ja09Q3ngf4ssQeF_jLykEOPIRahc6wcqVgpyAdHtim_r4n6-OVwJNul_fhd-oLoHyQT-x8v8Ge9JA2bk57ppk7b-2hmhIUg0lh4JkjWmZM61ldzyVIaQbut6UIz1K7t1oECAQHWpstCSVqpfiQuYxKUR45uE2aAoFJ50XRABk5J8P2xQbo2Sa1RsHhV2CqwBAdHtim96LzYVdxKGt_WJze89VrAkexAUL5YYaBIFHISfQf_T2kTgriMWgTbd2FBT1hrwxxgp7cLgwObJOHDS7cUYaalXineZyo0KnC1-yRSjeMgHY_QeZeDZT3jS-Wj7iN_-8QakEYIoh4XTbKTyaAKI0baeNgA2f_TY1mw2e1meqNsscOruNXst0g5RM4CM4IK14m6IWl7WZf68S3wFqWIF55NnfTCHjdOK4wolAdHtim-kjIOFEqpE2V0rkHlOpRZtGNNMv8MR77FmlLJbFy-h3A==",
						"functionCall": {
							"id": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571",
							"args": {
								"items": [
									"Item 1",
									"Item 2",
									"Item 3",
									"Item 4",
									"Item 5"
								]
							},
							"name": "render_ItemsList"
						}
					}
				],
				"role": "model"
			},
			"invocationId": "e-a1a8bf33-e77f-4e5a-b1a4-5f9c0170670b",
			"author": "GenericAgent",
			"actions": {
				"stateDelta": {},
				"artifactDelta": {},
				"requestedAuthConfigs": {},
				"requestedToolConfirmations": {}
			},

[rrazvd]

@trend-denny-lee right, but that is the tool calling and what about the tool result?

Look on messages states:

    {
        "id": "tool-result-1760622239565", // render_ItemsList tool result sent by client
        "role": "tool",
        "content": "{\"status\":\"success\",\"message\":\"Items were rendered successfully.\",\"itemsCount\":5}",
        "toolCallId": "adk-8ccd7b09-4c51-4352-be35-da49bc10a571"
    },

This message does not appear in the registered session

[contextablemark]

@rrazvd
If, as appears to be the case, the last two messages in that list were sent down in the same run, the issue is occurring because of this arriving after the tool-result message:

{
"id": "user-1760622531664",
"role": "user",
"content": "Cool"
}

Because so much of the ADK Middleware logic is based on the basic premise that "we need to deal with the possibility that the client is going to send down the entire history of the conversation with each request", there is code built around the assumption that the only message that matters is the last one received. This logic breaks when, as appears to be the case here, there are multiple relevant messages in the same payload (i.e., by looking at just the very last message received, the middleware "misses" the tool call result). It seems that your client only calls runAgent when the user enters a message (as opposed to CopilotKit which has "tool only runs" where the tool result is sent down before the user enters a follow-on message).

The obvious solution is to start tracking, at the session level, the IDs of all messages processed by the middleware in order to make sure that each message is processed once and only once, which I think would improve overall resiliency. I'll take a look at what would be involved with this approach.

[rrazvd]

@contextablemark Thank's @contextablemark, it makes sense. So, in my code i need to "force" a new runAgent when i have a client side tool result?

If so, this concerns me because the proper functioning of the protocol is left to the implementation external to HttpClient. I may be wrong, but wouldn't it be a good option for HttpClient to handle this internally to automatically execute a new run when it has a Tool Result?

[contextablemark]

@rrazvd I share your concern - this is why I've already started working on improving the resilience (and hopefully cleaning up some "special case" code in the process) by tracking the IDs of all processed messages instead of requiring changes in the httpClient (which would affect all client-side SDKs, not just Typescript) or changing application code to force a new runAgent call in order to mimic the behavior of CopilotKit.

[rrazvd]

@contextablemark Got it, I appreciate your attention for this, please keep me updated.

[contextablemark]

@contextablemark Got it, I appreciate your attention for this, please keep me updated.

@rrazvd A PR is pending, if you want to try it out.