[rachitm022]

Summary

• forward-port the AdCP 3.2 webhook challenge schema fix from fix(webhooks)!: comply with AdCP 3.2 challenge schema #1897 onto next
• require and validate seller_agent_url, delivery_auth, and event_types while preserving deprecated Bearer/HMAC delivery metadata
• preserve next signing-profile selection and require a sender capable of the configured profile
• validate generated payloads against the cached AdCP 3.2 schema without weakening receiver validation

This must land before release PR #1892 so 10.0.0b16 contains the fix.

BREAKING CHANGE: Webhook challenge helpers now require seller_agent_url and event_types, and proof challenges require an RFC 9421 sender.

Refs AI-21266.

Verification

• targeted webhook/conformance suite: 93 passed
• Ruff: passed
• mypy (SDK and reporting storage): passed
• strict adopter mypy fixtures: passed
• Pyright fixtures: passed (67 checked, 11 excluded)
• full pytest: 21,986 passed, 2,983 skipped; six unchanged reporting-interop tests cannot run on macOS because they require Linux /etc/os-release or /proc and will be exercised by Linux CI

Source

Forward-port of the implementation reviewed and merged in #1897, with conflict resolution for the AdCP 3.3 signing-profile support already present on next.

[aao-secretariat]

Ladon verdict: Approve

Approve.

Clean forward-port of #1897. The reviewer found no Critical/High/Medium findings.

Checks that passed review:

• Breaking marker is correct: fix(webhooks)!: carries the breaking signal for public exports challenge_webhook_destination and create_webhook_challenge_payload (snapshot lines 689/695), both of which gain required params (seller_agent_url/event_types) and challenge_webhook_destination now requires sender. Satisfies the mandatory semver-signal gate.
• Wire-shape fidelity: payload at webhooks.py:301-309 matches core/webhook-challenge.json 3.3.0-beta.5 exactly.
• No credential leak: legacy credentials are fingerprinted, not transmitted (asserted at tests/test_webhook_challenge.py:647); dropping _validate_header_value on the legacy path is safe since the credential never reaches a header.
• Schema validation fails closed (RuntimeError on missing validator); default token generation stays conformant with the schema pattern.

Decision-rule walkthrough: no critical/high findings (row 1 n/a); gated_paths false (row 2 n/a); high_risk reasons are all (modified) with no medium findings, so rows 3-5 do not fire; no prior decision (row 6 n/a); no no-auto-approve team match (row 7 n/a); zero medium findings (row 8 n/a). Falls through to row 9 → approve. The high_risk flag on src/adcp/signing/** is a heuristic LOOK signal only; modifications with no medium-or-higher findings are presumed safe.