Exercise 1: A LogQL Query for the Capstone's Own trace_id — Possible Solution
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{part_of="checkout-stack"} | json | trace_id = "4bf92f3577b34da6a3ce929d0e0e4736"

Explanation:

{part_of="checkout-stack"} is the label selector -- narrowing the
search down to only the log streams belonging to the four services
that make up this capstone's own stack, using the same shared label
the ServiceMonitor in Step 1 used for discovery. This is the cheap,
indexed part of the query, exactly matching obs1-7's own
label-selector-first pattern. | json parses each structured log line
so its fields (including trace_id) become directly queryable, and
| trace_id = "4bf92f3577b34da6a3ce929d0e0e4736" filters down to only
lines carrying that exact trace ID -- the one shown flowing through
Step 6's trace tree. Since every one of the four services shares the
part_of label, this single query would surface the matching log line
from whichever service actually emitted it (checkout-service, per
Step 5), without needing to know in advance which specific service to
look in.

WHY THIS WORKS AS AN ANSWER
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This builds a correctly structured LogQL query using the capstone's
own shared label for discovery and obs1-7's own label-then-filter
LogQL pattern, directly connecting the trace_id value shown in the
chapter's Step 5 log line and Step 6 trace tree.