Reporting metric coherence — deferred review findings (post-#6618 stack)

[bokelley]

A three-perspective review (protocol, buyer-workflow, code) of the delivery-reporting coherence stack (#6618 + #6620/#6621/#6622/#6626/#6627, plus #6616) produced findings that were fixed in the PRs, and the following accepted-but-deferred items. Recording them so they don't silently vanish; none blocks the stack.

1. Single-qualifier-per-(package, metric_id) is asserted, not enforced. get-media-buy-delivery-response.json justifies flat per-buy totals with "each buy is single-qualifier by definition," but committed-metric.json validates two entries with the same metric_id and different viewability_standard on one package — making such a commitment structurally unsatisfiable at package grain. Either enforce uniqueness at commitment validation or drop the by-definition claim. WG-level decision.

2. missing_metrics doesn't state where a leaf must appear (package totals vs any breakdown row). The sane reading for quartile_75 is quartile_data.q3_views present in package totals — one clause would make it a rule instead of a reading.

3. time_based_views: absent vs [] is undefined on a mixed video/display package (quartile_data uses null for not-applicable; the array has no analog).

4. reporting_dimensions.demographic is the only closed dimension block (additionalProperties: false) — 3.1 sellers hard-reject new fields there (e.g. sort_direction) but silently ignore them on the other dimensions. Pre-existing closure asymmetry; degradation behavior differs per dimension.

5. No video_starts metric exists, so cross-channel completion rates are all computed over impressions — autoplay-inflated on social, start-deflated on click-to-play olv — and completion_rate's meaning shifts per package when view_duration_seconds is set. Candidate for one honesty sentence in optimization-reporting.mdx, or a metric addition if buyers ask.

6. Conformance-grading note: with requested_metrics (feat(reporting): add requested_metrics to get_media_buy_delivery #6626), a buyer can sort by a metric excluded from the payload — graders MUST NOT attempt order-verification from response bodies in that case (the applied-sort echo is the contract surface).

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[bokelley]

Triage

Classification: Spec question (multi-item deferred review findings)
Bucket(s): spec / protocol, schema, compliance-suite
Status: deferred

Blocked-on: #6618 stack (#6620, #6621, #6622, #6626, #6627) — resurfaces when the stack lands.

Two notes for the WG queue when it does:

• Item 1 is a genuine schema-contract decision: the by-definition claim and the committed-metric schema are contradictory. Either enforce uniqueness or drop the claim — both paths are in scope, the WG pick is the gate.
• Item 4 is already governed by DR-0009 (published schemas default additionalProperties: true; tightening is breaking and policy-wide). The correct resolution is to remove the additionalProperties: false from demographic to align with the decision record — not to add it to the other dimensions.

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Triaged by Claude Code. Session: https://claude.ai/code

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