feat: subagent activity viewing by supreme-gg-gg · Pull Request #1513 · kagent-dev/kagent

supreme-gg-gg · 2026-03-17T05:30:02Z

Allows for viewing activity of subagents in the chat + fixes like user id passthrough for subagents

supreme-gg-gg · 2026-03-17T05:31:37Z

In action:

Screen.Recording.2026-03-16.at.4.12.53.PM.mov

How nested agent calls look like (note I set a max depth of 3, there is no theoretical max depth, but the UI looks really bad and it's not practical to have more than 3 layers of subagent calls...)

Copilot

Pull request overview

This PR adds end-to-end support for viewing subagent activity inline within the parent chat UI, and propagates user/source context through the A2A request chain so subagent sessions are stored and fetched correctly.

Changes:

UI: propagate subagent_session_id through tool call/result metadata and render an inline “Activity” panel that polls the subagent session’s tasks.
Python (ADK/Core): forward x-user-id and x-kagent-source headers for subagent calls; stamp subagent session ids into A2A DataPart metadata.
Go: persist a Session.Source field and filter subagent sessions out of agent session listings.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
ui/src/lib/messageHandlers.ts	Adds `subagent_session_id` extraction/propagation into processed tool call/result metadata.
ui/src/components/chat/ToolCallDisplay.tsx	Threads subagent session id into `AgentCallDisplay` for agent-tool calls.
ui/src/components/chat/AgentCallDisplay.tsx	Implements the expandable “Activity” panel with polling + nested chat rendering and depth limiting.
ui/src/app/actions/sessions.ts	Adds a helper to fetch subagent session + tasks for polling.
python/packages/kagent-core/src/kagent/core/a2a/_requests.py	Extracts forwarded user id and propagates subagent source tag via request context state.
python/packages/kagent-adk/src/kagent/adk/converters/event_converter.py	Stamps `subagent_session_id` into function_call DataPart metadata when provided.
python/packages/kagent-adk/src/kagent/adk/_session_service.py	Includes `source` in session creation payload.
python/packages/kagent-adk/src/kagent/adk/_remote_a2a_tool.py	Adds request interceptors for user/source headers; exposes a subagent session id in tool output.
python/packages/kagent-adk/src/kagent/adk/_agent_executor.py	Threads subagent session id mapping into the event converter; propagates source into session creation state.
go/core/internal/httpserver/handlers/sessions.go	Accepts and persists `source` from SessionRequest.
go/core/internal/database/fake/client.go	Filters out subagent sessions in agent session listing (fake DB).
go/core/internal/database/client.go	Filters out subagent sessions in agent session listing (real DB).
go/api/httpapi/types.go	Adds `source` to SessionRequest type.
go/api/database/models.go	Adds `Source` column to Session model.
docs/architecture/subagent-viewing.md	Documents the feature’s request/data flow.

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ui/src/components/chat/AgentCallDisplay.tsx

ui/src/app/actions/sessions.ts

ui/src/lib/messageHandlers.ts

supreme-gg-gg · 2026-03-17T15:49:08Z

python/packages/kagent-adk/src/kagent/adk/_remote_a2a_tool.py

+        # Pre-generate context_id for UI session polling
+        self._last_context_id: str = str(uuid.uuid4())
+
+    @property
+    def subagent_session_id(self) -> str | None:
+        """The subagent's session ID (== context_id sent in the A2A message)."""
+        return self._last_context_id


Tool instances are created fresh per request and destroyed after, so this _last_context_id UUID is effectively per-request already. For more info see the following comment, these three comments are all related to each other.

supreme-gg-gg · 2026-03-17T18:35:52Z

python/packages/kagent-adk/src/kagent/adk/_agent_executor.py

@@ -596,7 +604,11 @@ async def _handle_request(
                    run_metadata[get_kagent_metadata_key("invocation_id")] = real_invocation_id

                for a2a_event in convert_event_to_a2a_events(
-                    adk_event, invocation_context, context.task_id, context.context_id
+                    adk_event,
+                    invocation_context,
+                    context.task_id,
+                    context.context_id,
+                    subagent_session_ids=subagent_session_ids or None,
                ):


This sounds like an edge case, but when combined with the behaviour of the above comment, it's actually an intended feature. So the behaviour overall is:

User -> Main agent -> Subagent (multiple / parallel / sequential) -> they go into the same session for that subagent, the UI shows the same session -> each subagent return a response (existing behaviour) -> main agent

Now when user does another invocation of main agent:

User -> Main agent -> Runner gets recreated (existing behaviour) -> KagentRemoteA2ATool gets reset + session ID reset -> subagent (new session) -> ...

Because within each invocation the session ID for the same subagent is the same, therefore stamping the data part with the same ID mapped by name is not a problem. 😄

This is intended because when the main agent invokes the subagent sequentially, it's because it want to continue the conversation and the flow here is designed to support this.

supreme-gg-gg · 2026-03-17T18:42:46Z

python/packages/kagent-adk/src/kagent/adk/converters/event_converter.py

+def _process_subagent_session_id(a2a_part: A2APart, subagent_session_ids: Dict[str, str]) -> None:
+    """Stamps a subagent session ID onto a function_call DataPart.
+
+    If the part is a function_call whose tool name appears in
+    ``subagent_session_ids``, the corresponding session ID is added to
+    the DataPart metadata so the UI can find the subagent session.
+
+    Args:
+      a2a_part: The A2A part to potentially stamp.
+      subagent_session_ids: Mapping of tool name to pre-generated session ID.
+    """
+    if not isinstance(a2a_part.root, DataPart) or not a2a_part.root.metadata:
+        return
+    if (
+        a2a_part.root.metadata.get(get_kagent_metadata_key(A2A_DATA_PART_METADATA_TYPE_KEY))
+        != A2A_DATA_PART_METADATA_TYPE_FUNCTION_CALL
+    ):
+        return
+    tool_name = a2a_part.root.data.get("name") if isinstance(a2a_part.root.data, dict) else None
+    if tool_name and tool_name in subagent_session_ids:
+        a2a_part.root.metadata[get_kagent_metadata_key("subagent_session_id")] = subagent_session_ids[tool_name]


See above comment

docs/architecture/subagent-viewing.md

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> userid propagation to subagents Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> subagents Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> You are currently rebasing branch 'jetc/feat/subagent-viewing' on '802f95be'.

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg requested review from EItanya, ilackarms, peterj and yuval-k as code owners March 17, 2026 05:30

Copilot AI review requested due to automatic review settings March 17, 2026 05:30

Copilot started reviewing on behalf of supreme-gg-gg March 17, 2026 05:30 View session

Copilot AI reviewed Mar 17, 2026

View reviewed changes

supreme-gg-gg added 3 commits March 17, 2026 12:22

feat: subagent viewing

b3435ba

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> userid propagation to subagents Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> subagents Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

subagent fixes

ede4a1e

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io> You are currently rebasing branch 'jetc/feat/subagent-viewing' on '802f95be'.

docs

014c871

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

dobesv mentioned this pull request Mar 17, 2026

Ability to open sub-agent sessions in chat #1466

Closed

supreme-gg-gg added 3 commits March 17, 2026 12:28

cleanup

c9e1627

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

fix tests

59d684d

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

fix comments and rebase

f963623

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

supreme-gg-gg force-pushed the jetc/feat/subagent-viewing branch from 21df4cb to f963623 Compare March 17, 2026 17:03

supreme-gg-gg added 2 commits March 17, 2026 15:02

docs and fix lint

eec886e

Signed-off-by: Jet Chiang <pokyuen.jetchiang-ext@solo.io>

Merge branch 'main' into jetc/feat/subagent-viewing

c3b5bcd

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feat: subagent activity viewing#1513

feat: subagent activity viewing#1513
supreme-gg-gg wants to merge 8 commits intokagent-dev:mainfrom
supreme-gg-gg:jetc/feat/subagent-viewing

supreme-gg-gg commented Mar 17, 2026

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