fix(logging): use configurable max-depth when bounding logged tool_calls

requestLogger.ts's cloneBoundedForLog had its own hardcoded depth cap of 6,
independent of the existing configurable getChatLogMaxDepth(). A typical
Chat Completions response body's responseBody.choices[0].message.tool_calls[0].function
sits at exactly depth 6, so every logged tool call's function field
(name+arguments) was silently replaced with the literal string "[MaxDepth]"
before ever being stored — corrupting the data, not just how it renders.
Bumped the shared default 6->20 and switched requestLogger.ts to read it
instead of using its own literal.

(cherry picked from commit a2df6cf289)

open-sse/utils/requestLogger.ts

@@ -1,4 +1,5 @@
 import { getPendingById } from "@/lib/usage/usageHistory";
+import { getChatLogMaxDepth } from "@/lib/logEnv";
 import { sanitizeErrorMessage } from "./error.ts";
 
 type JsonRecord = Record<string, unknown>;
@@ -148,7 +149,7 @@ export function cloneBoundedForLog(value: unknown, depth = 0, key: string | null
   if (ArrayBuffer.isView(value)) {
     return `[binary ${(value as ArrayBufferView).byteLength} bytes]`;
   }
-  if (depth >= 6) return "[MaxDepth]";
+  if (depth >= getChatLogMaxDepth()) return "[MaxDepth]";
 
   if (Array.isArray(value)) {
     // Idempotence (#7847): an already-bounded array is [marker, ...tail] — MAX_LOG_ARRAY_ITEMS + 1

src/lib/logEnv.ts

@@ -150,8 +150,17 @@ export function getChatLogArrayTailItems(): number {
   return parsePositiveInt(process.env.CHAT_LOG_ARRAY_TAIL_ITEMS, 24);
 }
 
+/**
+ * Was a hardcoded 6 — trivially too shallow for real Chat Completions tool
+ * calls: `body.choices[0].message.tool_calls[0].function` alone is already
+ * 6 levels deep (body→choices→[i]→message→tool_calls→[i]→function), so
+ * EVERY logged tool call got its `function` field (name + arguments)
+ * replaced outright with the literal string "[MaxDepth]" before the name/
+ * arguments one level further in were ever reached — not an edge case, a
+ * universal truncation of tool-call data in call log artifacts.
+ */
 export function getChatLogMaxDepth(): number {
-  return parsePositiveInt(process.env.CHAT_LOG_MAX_DEPTH, 6);
+  return parsePositiveInt(process.env.CHAT_LOG_MAX_DEPTH, 20);
 }
 
 export function getChatLogMaxObjectKeys(): number {

tests/unit/request-logger-bounded-clone.test.ts

@@ -38,6 +38,40 @@ test("cloneBoundedForLog: nested tools field still exempt", () => {
   assert.equal(result.body.tools.length, 30);
 });
 
+// Regression: a Chat Completions response's tool_calls[].function is 6 levels
+// deep from the response body (body -> choices -> [i] -> message -> tool_calls
+// -> [i] -> function) — the depth cap used to be a hardcoded 6, so every
+// logged tool call's `function` (name + arguments) got replaced outright with
+// the literal string "[MaxDepth]", not just deeply truncated. This broke tool
+// call rendering in the request-detail view for ANY response with a tool
+// call — not an edge case, universal.
+test("cloneBoundedForLog: tool_calls[].function survives at its natural depth (was clobbered to '[MaxDepth]')", () => {
+  const body = {
+    choices: [
+      {
+        index: 0,
+        message: {
+          role: "assistant",
+          content: null,
+          tool_calls: [
+            {
+              id: "call_1",
+              type: "function",
+              function: { name: "write", arguments: '{"path":"/tmp/x","content":"hi"}' },
+            },
+          ],
+        },
+      },
+    ],
+  };
+  const result = cloneBoundedForLog(body) as {
+    choices: Array<{ message: { tool_calls: Array<{ function: unknown }> } }>;
+  };
+  const fn = result.choices[0].message.tool_calls[0].function;
+  assert.notEqual(fn, "[MaxDepth]", "function must not be clobbered to the MaxDepth placeholder");
+  assert.deepEqual(fn, { name: "write", arguments: '{"path":"/tmp/x","content":"hi"}' });
+});
+
 test("cloneBoundedForLog: top-level array without key context still truncated", () => {
   const arr = Array.from({ length: 45 }, (_, i) => i);
   const result = cloneBoundedForLog(arr) as unknown[];