docs(0262): link the cache verification report to ADR 0012 - #286
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The report measures the cache and asks for a reworded criterion; it did not say why the architecture was left alone rather than changed to avoid asking. ADR 0012 is that record, so the two are cross-linked and a reader arriving at either finds the other. The note is deliberately worded to close the alternatives rather than list them: a handler-written header and a CloudFront distribution are both rejected in the ADR with reasons, and someone proposing either again needs a new argument. Also repoints the task link at archive/ — 0122 was archived on 2026-09-04.
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Summary
Docs only. Follows the operator's decision of 2026-09-04: no CloudFront, no
X-Cacheheader at this point in the project — record the reasoning instead. That record is ADR 0012, already ondevelop. This PR is the cross-link.prices-api-cache-verification.mdmeasures the cache and asks for a reworded criterion, but it never said why the architecture was left alone rather than changed so the question would not arise. A reader arriving at either document now finds the other.The note is worded to close the alternatives rather than list them — both are rejected in the ADR with reasons, so proposing either again needs a new argument, not a re-reading.
Why the decision went this way, in one paragraph
The expensive hop is the database, and the stage cache already removes it — hits at 45–53 ms against misses at 78–145 ms, verified in 0122. Nothing in Tranche 2 asks for edge latency, and no measured user problem points at it. A handler-written
X-Cachewould report the opposite of the truth, proven with body hashes across a TTL boundary: the gateway replays cached bytes and the Lambda only runs on a miss. And CloudFront emitsX-Cache: Hit from cloudfront, so after 3–5 days of edge work the criterion's literal wording is still unmet and the same reviewer conversation is still required.Cost is explicitly not the reason — roughly neutral, with the certificate already in
us-east-1.The ADR carries a "when to revisit" list (distant-client latency becoming a real requirement, egress economics changing, or an edge-only launch requirement) and warns that another
X-Cacherequest is not on it.Also
Repoints the task link at
archive/— 0122 was archived on 2026-09-04.