docs(spec): split tracker contract and preview observation releases

[bokelley]

Summary

• move the format-scoped production tracker-execution contract in RFC: Measurement capability declaration (tracking_capabilities, attribution methodologies, TMP exposure data) #6207 into the AdCP 3.2 beta line
• keep preview observation sessions, runtime evidence, and URL-selector registry work in AdCP 3.3 under spec(creative): implement preview event and macro observation sessions #6782
• make the release boundary explicit across package snapshots, Trusted Match projection, conformance gates, and changesets

The 3.2 slice is limited to first-class pixel_tracker, vast_tracker, and daast_tracker assets. A contract-bearing package is pinned to an immutable snapshot whether or not the seller supports preview observation.

Validation

• all 16 JSON examples parse
• npm run test:docs-nav (28/28)
• git diff --check
• ad-tech, protocol, and code expert review

Related: #6207, #6782, #6775, #6767

[aao-secretariat]

Ladon verdict: Approve

Approve — doc-only edit to a nonnormative design draft.

What I checked:

• Single file changed: specs/tracker-execution-preview-observation.md, a nonnormative RFC-6207 design draft.
• No published protocol surface touched: no static/schemas/source/**, no docs/reference/**, no dist/** artifacts, no package.json version, no migrations. So no changeset/oneOf/schema-docs/immutability gate applies.
• The split into an additive AdCP 3.2 slice (first-class pixel/vast/daast trackers) and a 3.3 slice (URL selectors, preview observation, runtime evidence) is internally consistent: version tags on untouched examples remain correct, removed url-selector JSON still parses, and the Trusted Match projection stays fail-closed and digest-immutable.
• No blocking or Medium findings from the reviewer.

Gate checks: No no-auto-approve team match. gated_paths: false. high_risk: false. No prior decision. With zero findings and no escalation trigger, this falls through to row 9.

[aao-secretariat]

Ladon verdict: Approve

Approve.

Single-file delta to specs/tracker-execution-preview-observation.md, a nonnormative WG discussion draft. The PR restructures the versioning story: the first-class pixel/VAST/DAAST production tracker contract becomes additive AdCP 3.2 beta work, while URL-event selectors and preview observation move to AdCP 3.3. The split is applied coherently across version-gating prose, the contract example, the selector-union section, Trusted Match projection rules, ratification gates, conformance plan, and versioning.

No published-surface files touched (no static/schemas/source/**, dist/**, or docs/reference/**), so no changeset is required and the schema↔docs coherence, oneOf, and artifact-immutability gates do not apply. This is an editorial change to a draft, not a Breaking-class protocol change, so the breaking-change hard gate does not fire.

Decision table: no critical/high findings (row 1 n/a); gated_paths false (row 2 n/a); high_risk false with no deletions (rows 3/5 n/a); no medium findings (rows 4/8 n/a); no no-auto-approve team match (row 7 n/a). Prior decision was approve. Falls through to row 9 → approve.