feat(ui): finding → analysis trace entry points and the agent-trace viewer

[GabrielDrapor]

Makes the traces reachable. Four entry points:

• Runs table — the Finding ID becomes clickable, styled like the Run ID and Trace ID beside it, opening the analysis trace in the same in-page viewer panel the page already uses. It stays plain text while the analysis is running, when tracing failed, and for findings analysed before tracing existed; the hover title says which.
• Alert panel — a View analysis trace button swaps the viewer to the analysis trace; ← Back to trace returns.
• Sidebar — every finished assistant reply gets a View trace link next to its token count, opening the turn's trace in a sheet over the current page. Links appear only when trace_status = available.
• Viewer — an Agent badge in the header, and span names that read as what the agent did.

The invariant to review hardest: analysis traces never appear in the Traces list, and the viewer for customer traces is unchanged. The snapshot test of the user-trace viewer is taken in its own commit before the changes, so the diff proves it stayed byte-identical.

Closes #2064. Part of #2058.

Supersedes #2073, which GitHub auto-closed during a stack force-push and refuses to reopen. Review history lives on #2073.

[cubic-dev-ai]

2 issues found and verified against the latest diff

Confidence score: 3/5

• In frontend/ui/src/features/ai-assistant/components/message-list.tsx, streamed assistant messages do not receive the final traceId or traceStatus, so the completed turn lacks its View trace link; handle the final trace SSE event and annotate the current message.
• In frontend/ui/src/features/ai-assistant/components/ai-assistant-panel.tsx, tool-step Open span clicks store spanId but pass only traceId to the sheet, so the viewer opens at the trace root instead of the requested span; thread spanId through AgentTraceSh….

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="frontend/ui/src/features/ai-assistant/components/message-list.tsx">

<violation number="1" location="frontend/ui/src/features/ai-assistant/components/message-list.tsx:487">
P2: After a streamed turn completes, the new `View trace` link is absent because the live message never receives `traceId` or `traceStatus`. Handle the final `trace` SSE event and annotate the current assistant message, or reload the session messages when the run finishes.</violation>
</file>

<file name="frontend/ui/src/features/ai-assistant/components/ai-assistant-panel.tsx">

<violation number="1" location="frontend/ui/src/features/ai-assistant/components/ai-assistant-panel.tsx:250">
P2: Clicking a tool step's `Open span` link loses the requested span because this callback stores `spanId` but the sheet receives only `traceId`, opening the viewer at the trace root. Thread `spanId` through `AgentTraceSheet` and initialize or select that span in the viewer.</violation>
</file>

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Re-trigger cubic</sub>

[cubic-dev-ai]

P2: After a streamed turn completes, the new View trace link is absent because the live message never receives traceId or traceStatus. Handle the final trace SSE event and annotate the current assistant message, or reload the session messages when the run finishes.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At frontend/ui/src/features/ai-assistant/components/message-list.tsx, line 487:

<comment>After a streamed turn completes, the new `View trace` link is absent because the live message never receives `traceId` or `traceStatus`. Handle the final `trace` SSE event and annotate the current assistant message, or reload the session messages when the run finishes.</comment>

<file context>
@@ -460,6 +484,19 @@ function UsageFooter({ msg }: { msg: AIMessage }) {
           <span title="Estimated cost">${msg.costUsd.toFixed(4)}</span>
         </>
       )}
+      {msg.traceId && msg.traceStatus === "available" && onOpenTrace && (
+        <>
+          <span>&middot;</span>
</file context>

[GabrielDrapor]

Fixed in 5ba2f54. The stream parser only read data: lines, so the agent's NAMED trace event (event: trace) was dropped; it now tracks the event name and annotates the live assistant message with traceId/traceStatus, so the View trace link appears without a reload. Covered by two new use-ai-stream tests (available and disabled outcomes).

[cubic-dev-ai]

P2: Clicking a tool step's Open span link loses the requested span because this callback stores spanId but the sheet receives only traceId, opening the viewer at the trace root. Thread spanId through AgentTraceSheet and initialize or select that span in the viewer.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At frontend/ui/src/features/ai-assistant/components/ai-assistant-panel.tsx, line 250:

<comment>Clicking a tool step's `Open span` link loses the requested span because this callback stores `spanId` but the sheet receives only `traceId`, opening the viewer at the trace root. Thread `spanId` through `AgentTraceSheet` and initialize or select that span in the viewer.</comment>

<file context>
@@ -238,7 +244,11 @@ export function AiAssistantPanel({
+          <MessageList
+            messages={messages}
+            sessionStreaming={isStreaming}
+            onOpenTrace={(traceId, spanId) => setOpenTrace({ traceId, spanId })}
+          />
         )}
</file context>

[GabrielDrapor]

Correct within this PR's diff, and implemented by the stacked #2083: MessageList's onOpenTrace already captures spanId here, and #2083 threads it through AgentTraceSheet as initialSpanId with the deep-link selection logic (plus its own tests). Nothing further to change at this layer.

[cubic-dev-ai]

All reported issues were addressed across 7 files (changes from recent commits).

<sub>Tip: Review your code locally with the cubic CLI to iterate faster.

Fix all with cubic | Re-trigger cubic</sub>