Builds 232 and 233 held the Bedrock hit rate at 9% with the Claude Code
driver already sending byte-identical requests and headers, so something
between the proxy's ingress and the upstream still moves per build and
the flat key cannot say what.
Emit a digest per key component next to the counters: the test id, the
method, the URL, each keyed header, the whole body, and one digest per
top-level JSON body field. Values are digested, so no payload or
credential reaches the artifact. Diffing two builds' artifacts names the
field that moved.
Diagnostic, to be removed once it has answered.
