fix(combo): keep the caller's connection pin through the safety-net redirect

src/sse/handlers/chat.ts

@@ -1507,7 +1507,7 @@ async function handleSingleModelChat(
           {
             sessionId: "", // safety-net redirect doesn't have session context
             forceLiveComboTest: false,
-            forcedConnectionId: null,
+            forcedConnectionId: runtimeOptions?.forcedConnectionId ?? null,
             allowedConnectionIds: null,
             comboStepId: null,
             comboExecutionKey: null,

tests/unit/chat-safetynet-pin.test.ts

@@ -0,0 +1,41 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+
+// The safety-net redirect rebuilds the options for the inner call. The
+// caller's connection pin arrives as runtimeOptions.forcedConnectionId.
+// Hardcoding null there drops the pin, so a quota-weighted pool serves one
+// connection no matter which one the caller named. The emergency fallback is
+// a different path and still clears the pin.
+
+const source = fs.readFileSync(new URL("../../src/sse/handlers/chat.ts", import.meta.url), "utf8");
+
+function blockBetween(startMarker: string, endMarker: string): string {
+  const start = source.indexOf(startMarker);
+  assert.ok(start >= 0, `missing start marker ${startMarker}`);
+  const end = source.indexOf(endMarker, start + startMarker.length);
+  assert.ok(end > start, `missing end marker ${endMarker}`);
+  return source.slice(start, end);
+}
+
+function assignments(block: string): string[] {
+  return [...block.matchAll(/forcedConnectionId:\s*([^,\n]+)/g)].map((match) => match[1].trim());
+}
+
+test("safety-net combo redirect forwards the caller's connection pin", () => {
+  const found = assignments(
+    blockBetween("Safety-net combo redirect", "isModelAvailable: async () => true")
+  );
+  assert.ok(found.length > 0, "redirect block has no forcedConnectionId assignment");
+  for (const value of found) {
+    assert.notEqual(value, "null");
+    assert.match(value, /runtimeOptions/);
+  }
+});
+
+test("emergency fallback still clears the connection pin", () => {
+  const found = assignments(
+    blockBetween("EMERGENCY_FALLBACK", "no strategy for emergency fallback")
+  );
+  assert.ok(found.includes("null"), "emergency fallback no longer clears the pin");
+});