Canonical-formats conformance storyboard track — gates 3.1 GA promotion rubric

[bokelley]

Filed off the SDK-team implementor review on #3307 (creative formats canonical / canonical-formats).

Problem

The canonical-formats base schema is intentionally permissive: additionalProperties: true everywhere, x-canonical-policy-required-params-not-enforced on /schemas/formats/canonical/_base.json, no required parameter fields on any canonical. This is correct for the canonical (it's a loose contract — products narrow it) but it means JSON Schema validation passes on almost any conformant-shaped declaration.

The current "fixtures validate" evidence is Schroedinger conformance: the fixtures pass because they were authored against the schema, not because adopters' independent emissions would. Until we have a conformance harness that exercises:

• v1↔v2 projection in both directions (including divergence detection per RFC #3305 implementation preview — v2 creative formats (full spec, not for merge) #3307's new normative section)
• format_schema fetch contract (digest mismatch, $ref sandbox, invalid-schema handling) per IR3
• validate_input three-way result_kind discrimination across all 12 format_kind variants
• runtime_status skip-gating (compliance storyboards SHOULD gracefully skip declared_only)
• synthesis_nondeterministic × *_source compatibility rules from _base.json

…we don't actually know whether independent v2 emitters and consumers agree.

What this issue tracks

Build a canonical-formats storyboard track in the compliance harness (storyboard infrastructure already exists for other AdCP surfaces). Scope:

1. Producer storyboards: emit a product with format_ids + format_options (agreeing), format_ids only, format_options only, format_kind: "custom" (must have v2_only: true), divergent dual-emission (negative — must be flagged by consumer).
2. Consumer storyboards: read each producer-shape, assert the SDK projects/warns correctly (silent-loss-of-inventory must be caught).
3. format_schema fetch storyboards: serve a digest-matched schema, a digest-mismatched schema, an invalid-JSON-Schema body, a $ref-out-of-sandbox schema. Assert SDK responses (resolved / hard-fail / hard-fail / hard-fail with structured warning).
4. validate_input storyboards: per-canonical positive (validated_pass), per-canonical negative (validated_fail with violations), nondeterministic (unvalidatable_nondeterministic).
5. runtime_status skip-gate: assert declared_only entries are skipped gracefully, not failed.

Why this is GA-blocking, not 3.1-beta-blocking

The schema work is shippable as beta. The conformance harness is the artifact that lets us promote individual canonicals from preview to stable under the rubric in _base.json#status (2 adopters × 90 days no breakage). Without it, promotion is on vibes.

Dependencies

• Storyboard infrastructure already exists ([reference path needed])
• IR1 (v2_only) and IR3 (format_schema fetch contract) landed inline on RFC #3305 implementation preview — v2 creative formats (full spec, not for merge) #3307
• v1-canonical-mapping.json structural/glob matching is the basis for projection storyboards

Out of scope here

• Adapter-contract docs for sponsored_placement (IR5 — separate issue)
• Codegen-vs-runtime documentation (IR6 — landed inline on RFC #3305 implementation preview — v2 creative formats (full spec, not for merge) #3307)

Tracking: gates 3.1 GA promotion rubric for individual canonicals.

[bokelley]

Extends #4591 (canonical-formats conformance storyboard track).

Updated scope

Original issue framed storyboards by canonical (11 cells). The real complexity is the (canonical × production_source) matrix — a single audio_hosted canonical covers buyer_uploaded, publisher_host_recorded, and agent_synthesized with different required slots, validation rules, and SLA semantics.

Matrix cells (incomplete list)

For canonicals that carry audio_source / image_source / video_source / item_production_model:

• audio_hosted × {buyer_uploaded, publisher_host_recorded, agent_synthesized} = 3 storyboard cells
• video_hosted × {buyer_uploaded, agent_synthesized, seller_pre_rendered_from_brief} = 3 cells
• image × {buyer_uploaded, agent_synthesized, seller_pre_rendered_from_brief} = 3 cells
• sponsored_placement × item_production_model × fanout_mode = adapter-family-dependent (see sponsored_placement adapter-contract docs — gates canonical promotion to stable #4592)

Plus the canonical alone for: display_tag, video_vast, audio_daast (no production-source axis — render-verbatim).

Why this matters

Storyboards organized by canonical alone treat "audio_hosted ships fine" as evidence — but a seller's runtime may handle buyer-uploaded MP3 perfectly and silently fail on host-read script handoff. The matrix cells are the actual conformance unit.

Dependencies

• Per-slot consumed_for_production boolean lands inline on this PR (B1 from the second implementor review)
• IR5 sponsored_placement adapter-contract docs — gates canonical promotion to stable #4592 sponsored_placement adapter contracts feeds the matrix cell enumeration for that canonical

Tracking: matrix-cell enumeration is the conformance evidence required to promote Track-B canonicals from preview to stable post-GA.