Transaction traces

The Observability area includes a hierarchical transaction trace panel for recent coordinator runs. Open a project, go to Observability then Traces, and choose Preview trace on a run.

The trace tree is organized by span relationships:

1. Invoke Agent nodes represent agent turns.
2. Execute Tool nodes represent tool calls beneath the agent span that triggered them.
3. LLM nodes represent model calls. When the backend span carries model or token usage directly on an agent span, the UI synthesizes an LLM leaf so the hierarchy still shows agent to model.

Expand or collapse rows to follow the transaction. Select a span to inspect event time, duration, status, operation name, model, token usage, or tool name. If Application Insights has not produced trace data for the run yet, the panel shows an empty state.

For an Execute Tool span, the detail panel also shows the tool's arguments and output. These come from the persisted tool.call / tool.result / tool.error run events (matched to the span by callId), not from Application Insights, so they are available even when the AppInsights span itself only carries the tool name and status. A failed tool call shows its error message in place of the output, with distinct error styling. If no matching event is found (for example, an older run recorded before this correlation existed), the panel shows a placeholder message instead.

Each span, and the panel header, also shows an AIC (AI Credit) cost chip. An LLM span shows the cost of that one model turn; an Invoke Agent span shows the summed cost of every turn and tool call nested beneath it; the panel header shows the total cost across the whole run. The underlying value is agentweaver.aiu.nano (nano-AIU), sourced from the model turn's agent.turn.usage event and formatted with the same AIC unit used elsewhere in the app (see formatAic/CostChip).

Troubleshooting empty traces

An empty spans collection can mean that Application Insights has not produced trace data yet. If the trace query itself fails, the run-traces API response instead includes a non-null queryError value. The API also writes an Error-level log containing the query context and the truncated failing KQL, so operators can distinguish a query failure from a genuinely empty trace.

📸 Screenshot — observability-traces.pngShows: the Observability Traces tab listing recent coordinator runs with status badges, Open run, Preview trace, and Refresh. Path: open a project → click Observability → Traces → /projects/:projectId/observability/traces.

📸 Screenshot — observability-trace-preview.pngShows: the expanded Preview trace panel with the hierarchical transaction trace, span rows, and selected span details when AppInsights has data. Path: /projects/:projectId/observability/traces → click Preview trace.

Source

Concern	Source
Traces page route and preview action	apps/web/src/pages/observability/ObservabilityTracesPage.tsx:69
Hierarchical trace panel	apps/web/src/components/runs/TransactionTracePanel.tsx:294
Parent/child reconstruction and synthetic LLM leaf	apps/web/src/components/runs/traceTree.ts:22
Tool call argument/output correlation by callId	apps/web/src/components/runs/traceTree.ts:1 (buildToolCallIndex)
AIC cost aggregation per span/agent invocation/run	apps/web/src/components/runs/traceTree.ts (aggregateNanoAiu, totalNanoAiu)
Trace DTO	apps/Agentweaver.Api/Metrics/MetricsDtos.cs:133
Trace endpoint	apps/Agentweaver.Api/Endpoints/MetricsEndpoints.cs:130
AppInsights trace query and span classification	apps/Agentweaver.Api/Metrics/AppInsightsMetricsService.cs:522
Trace-query error response and Error-level logging	apps/Agentweaver.Api/Metrics/AppInsightsMetricsService.cs:585, apps/Agentweaver.Api/Metrics/AppInsightsMetricsService.cs:662
Persisted run event log (source of tool.call/tool.result/tool.error)	apps/Agentweaver.Api/Endpoints/RunEndpoints.cs:503

See also

• Events & observability
• Token usage monitoring