fix(xai): preserve stateful Responses output-only continuations

src/adapters/openai-responses/passthrough.ts

@@ -295,7 +295,15 @@ export function createResponsesPassthroughAdapter(provider: OcxProviderConfig):
       }
       const synthesizeMissingCallOutputs = !forward && (stateless || pairedToolResults);
       if (forward || stateless || pairedToolResults) {
-        outBody = repairOrphanedInputItems(outBody, unexpandedMiss, synthesizeMissingCallOutputs);
+        // A stateful destination can resolve an output-only delta against the call stored behind
+        // an unexpanded previous_response_id. All other shapes have no hidden call to preserve.
+        const repairOrphanOutputs = forward || stateless || !unexpandedMiss;
+        outBody = repairOrphanedInputItems(
+          outBody,
+          unexpandedMiss,
+          synthesizeMissingCallOutputs,
+          repairOrphanOutputs,
+        );
       }
       if (provider.dropResponsesReasoningItems === true) {
         outBody = dropResponsesReasoningInputItems(outBody);

src/adapters/openai-responses/tool-output-recovery.ts

@@ -194,7 +194,8 @@ export function repairUnidentifiedToolOutputItems(body: unknown): unknown {
  *   reasoning-bearing assistant turn (#1477). Gated on
  *   `synthesizeMissingCallOutputs` (stateless AND non-forward wires); forward replay keeps
  *   fail-closed behavior.
- * - `function_call_output`/`custom_tool_call_output` without their paired call item
+ * - `function_call_output`/`custom_tool_call_output` without their paired call item, when
+ *   `repairOrphanOutputs` is enabled
  *   ("No tool call found for function call output with call_id ..."). Converted to user
  *   messages so the result text survives. `function_call_output` also pairs with
  *   `local_shell_call` (codex-rs emits shell outputs as function_call_output).
@@ -340,7 +341,12 @@ export function restoreBridgedWebSearchCalls(body: unknown, destinationScope: st
   return changed ? { ...body, input: restored } : body;
 }
 
-export function repairOrphanedInputItems(body: unknown, dropReasoning: boolean, synthesizeMissingCallOutputs = false): unknown {
+export function repairOrphanedInputItems(
+  body: unknown,
+  dropReasoning: boolean,
+  synthesizeMissingCallOutputs = false,
+  repairOrphanOutputs = true,
+): unknown {
   if (!isPlainObject(body) || !Array.isArray(body.input)) return body;
   const input = body.input;
 
@@ -379,7 +385,7 @@ export function repairOrphanedInputItems(body: unknown, dropReasoning: boolean,
       // incomplete. With no call id and no output, preserve the invalid item so validation fails
       // closed rather than pretending any tool result exists.
       const knownNullOutput = callId.length > 0 && item.output == null;
-      if (!paired && (knownNullOutput || usableOutput)) {
+      if (repairOrphanOutputs && !paired && (knownNullOutput || usableOutput)) {
         changed = true;
         repaired.push({
           type: "message",

structure/providers/chat-compat.md

@@ -194,8 +194,10 @@ xAI's public Responses API is stateful (`store` defaults true; `previous_respons
 stored conversation), so the provider is not marked `statelessResponses`. The pairing repair
 synthesizes an honest unknown-status placeholder without touching `store` or
 `previous_response_id`: repairing an interrupted history must not cost the thread its server-side
-state. Forward auth suppresses the synthesis regardless of the flag, because the backend that holds
-the conversation can resolve the pair itself.
+state. An output-only continuation is preserved because its call may live in that server-side state;
+pairing only synthesizes results for calls present in the current input. Forward auth suppresses the
+synthesis regardless of the flag, because the backend that holds the conversation can resolve the
+pair itself.
 
 > Decision record: [ADR-0052](../decisions/ADR-0052-reasoning-and-tool-result-compatibility.md)
 

tests/adapters/openai/openai-chat-dangling-toolcalls.test.ts

@@ -12,6 +12,10 @@ const provider: OcxProviderConfig = {
   baseUrl: "https://example.test/v1",
   apiKey: "sk-test",
   authMode: "key",
+  // The wire role folds to `system` unless a destination is recorded as accepting
+  // `developer`; this suite is about tool-result repair ordering, so it declares the
+  // destination rather than asserting the default.
+  foldDeveloperRoleToSystem: false,
 };
 
 interface ChatMsg {

tests/providers/xai/xai-responses-adjacency.test.ts

@@ -27,6 +27,9 @@ function buildBody(provider: OcxProviderConfig, rawBody: Record<string, unknown>
     context: { messages: [] },
     stream: true,
     options: {},
+    previousResponseId: typeof rawBody.previous_response_id === "string"
+      ? rawBody.previous_response_id
+      : undefined,
     _rawBody: { model: MODEL, ...rawBody },
   } as Parameters<ReturnType<typeof createResponsesPassthroughAdapter>["buildRequest"]>[0], {
     headers: new Headers(),
@@ -91,6 +94,25 @@ describe("xAI Responses tool-result adjacency", () => {
     expect(body.input).toEqual([call, output, injected]);
   });
 
+  test("preserves output-only continuations whose call remains in xAI state", () => {
+    const functionOutput = { type: "function_call_output", call_id: "call_stored", output: "result" };
+    const customOutput = { type: "custom_tool_call_output", call_id: "custom_stored", output: "patch" };
+    const body = buildBody(xaiOauthResponses({ requiresPairedResponsesToolResults: true }), {
+      previous_response_id: "resp_xai_store",
+      store: true,
+      input: [functionOutput, customOutput],
+    });
+
+    expect(body.previous_response_id).toBe("resp_xai_store");
+    expect(body.store).toBe(true);
+    expect(body.input).toEqual([functionOutput, customOutput]);
+
+    const standalone = buildBody(xaiOauthResponses({ requiresPairedResponsesToolResults: true }), {
+      input: [functionOutput],
+    });
+    expect(standalone.input).toEqual([expect.objectContaining({ type: "message", role: "user" })]);
+  });
+
   test("keeps call_id pairing for two outstanding replayed calls and synthesizes only the missing output", () => {
     const provider = xaiOauthResponses({
       requiresAdjacentResponsesToolResults: true,

tests/responses/chat-inline-document-bytes.test.ts

@@ -28,6 +28,10 @@ const chatProvider: OcxProviderConfig = {
   adapter: "openai-chat",
   baseUrl: "https://gateway.example.internal/v1",
   apiKey: "k",
+  // The wire role folds to `system` unless a destination is recorded as accepting
+  // `developer`; the document test asserts the role a turn keeps, so it declares the
+  // destination rather than asserting the default.
+  foldDeveloperRoleToSystem: false,
 };
 const anthropicProvider = {
   adapter: "anthropic",