fix(tracing): seed log context before route-thinking to fix gen_ai.conversation.id on gen_ai.chat spans

[dcramer]

Problem

In the queue-worker path (POST /api/internal/agent/continue), gen_ai.conversation.id is missing from the gen_ai.chat span emitted during thinking-level routing (the Haiku router call).

OTel GenAI semconv marks gen_ai.conversation.id as Conditionally Required on gen_ai.chat and gen_ai.invoke_agent spans. All other gen_ai.* spans in Junior already carry it — this was the one gap.

Root cause

gen_ai.conversation.id propagates via AsyncLocalStorage. spanContext (which has conversationId) is computed before selectTurnThinkingLevel is called, but hasn't been installed into ALS yet at that point. So the chat.route_thinking + its nested gen_ai.chat span both miss the attribute in queue-worker turns.

The Slack inline path is unaffected: slack-runtime.ts wraps the full turn in withSpan('chat.turn', ..., context) which seeds ALS with conversationId before selectTurnThinkingLevel runs.

Fix

Wrap the awaited selectTurnThinkingLevel call in withLogContext(spanContext, ...). This is a scoped seed — it only covers the route-thinking subtree, leaves everything else unchanged, and works identically in both code paths.

- thinkingSelection = await selectTurnThinkingLevel({ ... });
+ thinkingSelection = await withLogContext(spanContext, () =>
+   selectTurnThinkingLevel({ ... }),
+ );

Verification

After this change, in queue-worker turns:

• chat.route_thinking has gen_ai.conversation.id ✓
• gen_ai.chat inside route-thinking has gen_ai.conversation.id ✓
• All existing spans unaffected ✓

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Project	Deployment	Actions	Updated (UTC)
junior-docs	Ready	Preview, Comment	Jun 17, 2026 9:31pm

[dcramer]

Closing — the premise is wrong per OTel semconv. The router (Haiku) call is a one-shot classifier with no conversation context, so its gen_ai.chat span correctly has no gen_ai.conversation.id. Spec footnote [4] says to only set it when an identifier is available for that operation. Trace parent-child links are the right mechanism here. The actual investigation this spun out of (missing auth-prompt trace) is a separate, still-open question.