fix(compat): warn when brand_manifest non-standard path is silently flattened to domain

src/adcp/compat/legacy/v2_5/_media_buy_helpers.py

@@ -12,10 +12,20 @@
 
 from __future__ import annotations
 
+import logging
 from typing import Any
+from urllib.parse import urlparse
 
 from adcp.compat.legacy.v2_5._url import extract_brand_domain
 
+_logger = logging.getLogger(__name__)
+
+# Paths that v3 sellers reconstruct correctly — no information is lost.
+_STANDARD_BRAND_MANIFEST_PATHS = {"", "/", "/.well-known/brand.json"}
+
+# Per-URL dedup so high-RPS v2.5 buyers don't saturate the log pipeline.
+_brand_manifest_path_warned: set[str] = set()
+
 
 def adapt_brand_manifest_to_brand(payload: dict[str, Any]) -> dict[str, Any]:
     """Rewrite v2.5 ``brand_manifest`` (URL string or inline BrandManifest
@@ -34,7 +44,22 @@ def adapt_brand_manifest_to_brand(payload: dict[str, Any]) -> dict[str, Any]:
     out = dict(payload)
     manifest = out.pop("brand_manifest", None)
     if isinstance(manifest, str) and manifest and "brand" not in out:
-        out["brand"] = {"domain": extract_brand_domain(manifest)}
+        domain = extract_brand_domain(manifest)
+        parsed = urlparse(manifest.strip())
+        if (
+            parsed.hostname is not None
+            and parsed.path not in _STANDARD_BRAND_MANIFEST_PATHS
+            and manifest not in _brand_manifest_path_warned
+        ):
+            _brand_manifest_path_warned.add(manifest)
+            _logger.warning(
+                "brand_manifest at %s uses a non-standard path; "
+                "v3 sellers derive %s/.well-known/brand.json from BrandReference.domain. "
+                "Manifest fetch may 404.",
+                manifest,
+                domain,
+            )
+        out["brand"] = {"domain": domain}
     elif isinstance(manifest, dict) and "brand" not in out:
         url = manifest.get("url")
         if isinstance(url, str) and url.strip():

src/adcp/compat/legacy/v2_5/get_products.py

@@ -36,12 +36,22 @@
 
 from __future__ import annotations
 
+import logging
 from typing import Any
+from urllib.parse import urlparse
 
 from adcp.compat.legacy import register_adapter
 from adcp.compat.legacy.types import AdapterPair
 from adcp.compat.legacy.v2_5._url import extract_brand_domain
 
+_logger = logging.getLogger(__name__)
+
+# Paths that v3 sellers reconstruct correctly — no information is lost.
+_STANDARD_BRAND_MANIFEST_PATHS = {"", "/", "/.well-known/brand.json"}
+
+# Per-URL dedup so high-RPS v2.5 buyers don't saturate the log pipeline.
+_brand_manifest_path_warned: set[str] = set()
+
 # v2.5 channel buckets to v3 channel slugs. Multi-mapped buckets resolve
 # to all listed v3 channels; downstream consumers can narrow further via
 # ``filters.channels`` if needed.
@@ -135,7 +145,22 @@ def adapt_request(payload: dict[str, Any]) -> dict[str, Any]:
     # v3 validation handle the missing field.
     brand_manifest = out.pop("brand_manifest", None)
     if isinstance(brand_manifest, str) and brand_manifest and "brand" not in out:
-        out["brand"] = {"domain": extract_brand_domain(brand_manifest)}
+        domain = extract_brand_domain(brand_manifest)
+        parsed = urlparse(brand_manifest.strip())
+        if (
+            parsed.hostname is not None
+            and parsed.path not in _STANDARD_BRAND_MANIFEST_PATHS
+            and brand_manifest not in _brand_manifest_path_warned
+        ):
+            _brand_manifest_path_warned.add(brand_manifest)
+            _logger.warning(
+                "brand_manifest at %s uses a non-standard path; "
+                "v3 sellers derive %s/.well-known/brand.json from BrandReference.domain. "
+                "Manifest fetch may 404.",
+                brand_manifest,
+                domain,
+            )
+        out["brand"] = {"domain": domain}
     elif isinstance(brand_manifest, dict) and "brand" not in out:
         url = brand_manifest.get("url")
         if isinstance(url, str) and url.strip():

tests/test_legacy_adapter_v2_5_get_products.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import logging
 from typing import Any
 
 from adcp.compat.legacy import get_legacy_adapter
@@ -139,6 +140,64 @@ def test_brand_manifest_inline_object_brand_wins_when_both_present() -> None:
     assert "brand_manifest" not in out
 
 
+# ---------------------------------------------------------------------------
+# Request: brand_manifest non-standard-path warning (issue #683)
+# ---------------------------------------------------------------------------
+
+_GP_LOGGER = "adcp.compat.legacy.v2_5.get_products"
+
+
+def test_brand_manifest_cdn_url_warns(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """CDN brand_manifest with non-standard path emits a WARNING about the
+    information loss so operators can debug downstream 404s."""
+    import adcp.compat.legacy.v2_5.get_products as _gp
+
+    monkeypatch.setattr(_gp, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_GP_LOGGER):
+        out = _adapt({"brand_manifest": "https://cdn.acmecorp.com/brand-manifest.json"})
+    assert out["brand"] == {"domain": "cdn.acmecorp.com"}
+    records = [r for r in caplog.records if r.name == _GP_LOGGER]
+    assert len(records) == 1
+    msg = records[0].getMessage()
+    assert "non-standard path" in msg
+    assert "cdn.acmecorp.com" in msg
+
+
+def test_brand_manifest_well_known_path_no_warning(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Standard /.well-known/brand.json path does NOT warn — v3 derives the
+    same URL that the buyer originally pointed at."""
+    import adcp.compat.legacy.v2_5.get_products as _gp
+
+    monkeypatch.setattr(_gp, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_GP_LOGGER):
+        _adapt({"brand_manifest": "https://acme.com/.well-known/brand.json"})
+    assert not any(r.name == _GP_LOGGER for r in caplog.records)
+
+
+def test_brand_manifest_bare_domain_no_warning(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Bare domain brand_manifest (no scheme) does not false-positive — urlparse
+    returns hostname=None for schemeless strings so we skip the path check."""
+    import adcp.compat.legacy.v2_5.get_products as _gp
+
+    monkeypatch.setattr(_gp, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_GP_LOGGER):
+        _adapt({"brand_manifest": "acme.com"})
+    assert not any(r.name == _GP_LOGGER for r in caplog.records)
+
+
+def test_brand_manifest_cdn_url_warns_once_dedup(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Same CDN URL repeated across requests only logs one warning (dedup)."""
+    import adcp.compat.legacy.v2_5.get_products as _gp
+
+    monkeypatch.setattr(_gp, "_brand_manifest_path_warned", set())
+    url = "https://cdn.acmecorp.com/brand-manifest.json"
+    with caplog.at_level(logging.WARNING, logger=_GP_LOGGER):
+        _adapt({"brand_manifest": url})
+        _adapt({"brand_manifest": url})
+    records = [r for r in caplog.records if r.name == _GP_LOGGER]
+    assert len(records) == 1
+
+
 # ---------------------------------------------------------------------------
 # Request: promoted_offerings → catalog
 # ---------------------------------------------------------------------------

tests/test_legacy_adapter_v2_5_media_buy.py

@@ -7,6 +7,7 @@
 
 from __future__ import annotations
 
+import logging
 from typing import Any
 
 from adcp.compat.legacy import get_legacy_adapter
@@ -119,6 +120,66 @@ def test_create_media_buy_brand_manifest_inline_object_brand_wins_when_both_pres
     assert "brand_manifest" not in out
 
 
+# ---------------------------------------------------------------------------
+# create_media_buy: brand_manifest non-standard-path warning (issue #683)
+# ---------------------------------------------------------------------------
+
+_MB_HELPERS_LOGGER = "adcp.compat.legacy.v2_5._media_buy_helpers"
+
+
+def test_create_media_buy_cdn_url_warns(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """CDN brand_manifest with non-standard path emits a WARNING about the
+    information loss so operators can debug downstream 404s."""
+    import adcp.compat.legacy.v2_5._media_buy_helpers as _mbh
+
+    monkeypatch.setattr(_mbh, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_MB_HELPERS_LOGGER):
+        out = v2_5_cmb.adapt_request(
+            {"brand_manifest": "https://cdn.acmecorp.com/brand-manifest.json"}
+        )
+    assert out["brand"] == {"domain": "cdn.acmecorp.com"}
+    records = [r for r in caplog.records if r.name == _MB_HELPERS_LOGGER]
+    assert len(records) == 1
+    msg = records[0].getMessage()
+    assert "non-standard path" in msg
+    assert "cdn.acmecorp.com" in msg
+
+
+def test_create_media_buy_well_known_path_no_warning(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Standard /.well-known/brand.json path does NOT warn."""
+    import adcp.compat.legacy.v2_5._media_buy_helpers as _mbh
+
+    monkeypatch.setattr(_mbh, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_MB_HELPERS_LOGGER):
+        v2_5_cmb.adapt_request(
+            {"brand_manifest": "https://acme.com/.well-known/brand.json"}
+        )
+    assert not any(r.name == _MB_HELPERS_LOGGER for r in caplog.records)
+
+
+def test_create_media_buy_bare_domain_no_warning(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Bare domain brand_manifest (no scheme) does not false-positive."""
+    import adcp.compat.legacy.v2_5._media_buy_helpers as _mbh
+
+    monkeypatch.setattr(_mbh, "_brand_manifest_path_warned", set())
+    with caplog.at_level(logging.WARNING, logger=_MB_HELPERS_LOGGER):
+        v2_5_cmb.adapt_request({"brand_manifest": "acme.com"})
+    assert not any(r.name == _MB_HELPERS_LOGGER for r in caplog.records)
+
+
+def test_create_media_buy_cdn_url_warns_once_dedup(caplog, monkeypatch) -> None:  # type: ignore[no-untyped-def]
+    """Same CDN URL repeated across requests only logs one warning (dedup)."""
+    import adcp.compat.legacy.v2_5._media_buy_helpers as _mbh
+
+    monkeypatch.setattr(_mbh, "_brand_manifest_path_warned", set())
+    url = "https://cdn.acmecorp.com/brand-manifest.json"
+    with caplog.at_level(logging.WARNING, logger=_MB_HELPERS_LOGGER):
+        v2_5_cmb.adapt_request({"brand_manifest": url})
+        v2_5_cmb.adapt_request({"brand_manifest": url})
+    records = [r for r in caplog.records if r.name == _MB_HELPERS_LOGGER]
+    assert len(records) == 1
+
+
 # ---------------------------------------------------------------------------
 # Package request: creative_ids → creative_assignments (both tools)
 # ---------------------------------------------------------------------------