diff --git a/src/agents/live-cache-regression-runner.ts b/src/agents/live-cache-regression-runner.ts
index 559f775c585..206a902d99f 100644
--- a/src/agents/live-cache-regression-runner.ts
+++ b/src/agents/live-cache-regression-runner.ts
@@ -21,6 +21,7 @@ const OPENAI_TIMEOUT_MS = 120_000;
 const ANTHROPIC_TIMEOUT_MS = 120_000;
 const LIVE_CACHE_LANE_RETRIES = 1;
 const LIVE_CACHE_RESPONSE_RETRIES = 2;
+const OPENAI_CACHE_REASONING = "low" as unknown as never;
 const OPENAI_PREFIX = buildStableCachePrefix("openai");
 const OPENAI_MCP_PREFIX = buildStableCachePrefix("openai-mcp-style");
 const ANTHROPIC_PREFIX = buildStableCachePrefix("anthropic");
@@ -168,7 +169,7 @@ async function runToolOnlyTurn(params: {
     sessionId: params.sessionId,
     maxTokens: 128,
     temperature: 0,
-    ...(params.providerTag === "openai" ? { reasoning: "none" as unknown as never } : {}),
+    ...(params.providerTag === "openai" ? { reasoning: OPENAI_CACHE_REASONING } : {}),
   };
   let prompt = `Call the tool \`${params.tool.name}\` with {}. IMPORTANT: respond ONLY with the tool call and no other text.`;
   let response = await completeSimpleWithLiveTimeout(
@@ -243,7 +244,7 @@ async function completeCacheProbe(params: {
         sessionId: params.sessionId,
         maxTokens: params.maxTokens ?? 64,
         temperature: 0,
-        ...(params.providerTag === "openai" ? { reasoning: "none" as unknown as never } : {}),
+        ...(params.providerTag === "openai" ? { reasoning: OPENAI_CACHE_REASONING } : {}),
       },
       `${params.providerTag} cache lane ${params.suffix}`,
       timeoutMs,