fix(version): keep protocol envelope fields when converting responses down

.changeset/projection-keeps-envelope.md

@@ -0,0 +1,5 @@
+---
+'@adcp/sdk': patch
+---
+
+Version translation no longer removes protocol envelope fields. When a response was converted down to an older release whose task schema didn't compose the protocol envelope (the 3.2 proposal-flow responses, which AdCP 3.2.x and 3.3 fix as DR-0036 correction (b)), the schema projection treated `status`, `message`, `context` and the other envelope fields as newer-only and removed them, so a 3.2 buyer could receive a 3.3 server's `list_products` response without its `status`. The projection now keeps every property the release's protocol and version envelopes declare at the payload root.

src/lib/adapters/version/schema-projection.ts

@@ -261,7 +261,8 @@ function project(
   target: SchemaNode[],
   path: string,
   dropped: ProjectionDrop[],
-  depth: number
+  depth: number,
+  protectedKeys: ReadonlySet<string> = NO_PROTECTED_KEYS
 ): unknown {
   if (depth > MAX_DEPTH || source.length === 0 || target.length === 0) return value;
   const sourceExpansions = source.map(node => expand(node, value, depth));
@@ -323,6 +324,10 @@ function project(
     const sourceSchemas = schemasForKey(sourceIndex, key) ?? nonEmpty(sourceIndex.additional);
     const targetSchemas = schemasForKey(targetIndex, key) ?? nonEmpty(targetIndex.additional);
     const entryPath = joinPath(path, key);
+    if (protectedKeys.has(key)) {
+      out[key] = entry;
+      continue;
+    }
     if (sourceIndex.declares && targetIndex.declares && schemasForKey(sourceIndex, key) && !targetSchemas) {
       dropped.push({ path: entryPath, kind: 'field' });
       changed = true;
@@ -371,10 +376,53 @@ export function projectToolPayload<T>(
   const target = toolRoot(toolName, direction, toVersion);
   if (!source || !target || !isObject(payload)) return { value: payload, dropped: [] };
   const dropped: ProjectionDrop[] = [];
-  const projected = project(payload, [source], [target], '', dropped, 0);
+  const projected = project(payload, [source], [target], '', dropped, 0, envelopeKeys(toVersion));
   return { value: (projected === OMIT ? payload : projected) as T, dropped };
 }
 
+const NO_PROTECTED_KEYS: ReadonlySet<string> = new Set();
+
+/** Envelope fields the protocol has defined since 3.0, used when a bundle omits the envelope schemas. */
+const BASELINE_ENVELOPE_KEYS = [
+  'adcp_error',
+  'adcp_major_version',
+  'adcp_version',
+  'context',
+  'context_id',
+  'governance_context',
+  'message',
+  'payload',
+  'push_notification_config',
+  'replayed',
+  'status',
+  'task_id',
+  'timestamp',
+];
+
+const envelopeKeyCache = new Map<string, ReadonlySet<string>>();
+
+/**
+ * Root-level fields of the protocol and version envelopes. The envelope
+ * applies to every task payload whether or not a task schema composes it
+ * (some 3.2 proposal-flow responses did not, which DR-0036 correction (b)
+ * fixes), so the projection never removes them.
+ */
+function envelopeKeys(version: string): ReadonlySet<string> {
+  const cached = envelopeKeyCache.get(version);
+  if (cached) return cached;
+  const keys = new Set(BASELINE_ENVELOPE_KEYS);
+  for (const ref of ['core/protocol-envelope.json', 'core/version-envelope.json']) {
+    try {
+      const properties = getSchemaDocumentByRef(ref, version)?.schema.properties;
+      if (isObject(properties)) for (const key of Object.keys(properties)) keys.add(key);
+    } catch {
+      // A bundle without the envelope schemas keeps the baseline set.
+    }
+  }
+  envelopeKeyCache.set(version, keys);
+  return keys;
+}
+
 /** Whether the release's schema bundle defines a request schema for the tool. */
 export function releaseDefinesTool(toolName: string, version: string): boolean {
   try {

test/fixtures/version-translation/vectors.json → test/fixtures/version-translation/3.2-3.1.json

@@ -1,5 +1,5 @@
 {
-  "description": "Cross-version translation between consecutive AdCP minor releases (DR-0032, DR-0033): request down-conversion and response up-conversion on the client, response down-conversion on the server, release negotiation, and one-to-one account-key reduction.",
+  "description": "Cross-version translation between AdCP 3.2 and 3.1 (DR-0032, DR-0033), chained to 3.0 where noted: client request down-conversion and response up-conversion, server response down-conversion, release negotiation, and one-to-one reduction of the account key 3.2 changed on schemas 3.1 published closed.",
   "reference_implementation": "@adcp/sdk (adcontextprotocol/adcp-client#3372, #3376)",
   "version_pair": ["3.2", "3.1"],
   "cases": [
@@ -1072,5 +1072,5 @@
       ]
     }
   ],
-  "status": "proposed (DR-0032 and DR-0033 pending ratification; DR-0034 escalated)"
+  "status": "proposed (DR-0032, DR-0033)"
 }