diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52b0731b2..bc9e660bc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,15 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## Unreleased
 
+### Naming a conversation asks the endpoint OPENAI_BASE_URL names, not OpenAI
+
+The job that names a conversation sent its request to api.openai.com whatever `OPENAI_BASE_URL` said,
+while the Bots, the router and tool selection all used the configured endpoint. A deployment behind a
+gateway, a proxy or a local model therefore sent its model key, and the opening of every
+conversation, to OpenAI; OpenAI refused the key, so no conversation was ever named. The request now
+goes to the same endpoint as every other model call. A deployment that never set `OPENAI_BASE_URL`
+behaves as before.
+
 ### A Bot's question to a person survives a route that fails
 
 Who "a person" is, is a seam a deployment fills in with its own on-call rota or duty desk. If that
diff --git a/server/src/channels/titler.ts b/server/src/channels/titler.ts
index 6032935a1..5556d968d 100644
--- a/server/src/channels/titler.ts
+++ b/server/src/channels/titler.ts
@@ -2,11 +2,9 @@
  * One model call for a few words. Not a Bot and not a turn: a title is not said to anybody and is
  * not part of the conversation it names, so there is no runtime work and no thread to hold.
  */
+import { chatCompletionsUrl } from "../routing/model";
 import { oneLine } from "./text";
 
-/** Where an OpenAI-compatible provider answers, overridable the way `agent-bot` overrides it. */
-const DEFAULT_BASE_URL = "https://api.openai.com/v1";
-
 /** Rules, not an example: a model copies an example's subject as readily as its shape. */
 const INSTRUCTION = [
   "You name conversations, like a title in a sidebar.",
@@ -20,7 +18,7 @@ export type TitlerOptions = {
   model: string;
   /** Resolved per call, so a rotated credential is picked up without a restart. */
   resolveApiKey: () => Promise<string | null>;
-  baseUrl?: string;
+  environment?: Record<string, string | undefined>;
   /** Injectable so a test drives this without a network. */
   fetchImpl?: typeof fetch;
   /** How long one call may take before it is given up on. */
@@ -30,29 +28,31 @@ export type TitlerOptions = {
 /** No key resolves to null and is not retried; a provider error throws, so the queue retries it. */
 export function createChannelTitler(options: TitlerOptions) {
   const call = options.fetchImpl ?? fetch;
-  const baseUrl = (options.baseUrl ?? DEFAULT_BASE_URL).replace(/\/+$/, "");
 
   return async (excerpt: string): Promise<string | null> => {
     const apiKey = await options.resolveApiKey();
     if (!apiKey) return null;
 
-    const response = await call(`${baseUrl}/chat/completions`, {
-      method: "POST",
-      headers: {
-        "content-type": "application/json",
-        authorization: `Bearer ${apiKey}`,
+    const response = await call(
+      chatCompletionsUrl(options.environment ?? process.env),
+      {
+        method: "POST",
+        headers: {
+          "content-type": "application/json",
+          authorization: `Bearer ${apiKey}`,
+        },
+        body: JSON.stringify({
+          model: options.model,
+          messages: [
+            { role: "system", content: INSTRUCTION },
+            { role: "user", content: excerpt },
+          ],
+          // Reasoning tokens come out of this budget, so a cap sized for the answer alone 400s.
+          max_completion_tokens: 512,
+        }),
+        signal: AbortSignal.timeout(options.timeoutMs ?? 20_000),
       },
-      body: JSON.stringify({
-        model: options.model,
-        messages: [
-          { role: "system", content: INSTRUCTION },
-          { role: "user", content: excerpt },
-        ],
-        // Reasoning tokens come out of this budget, so a cap sized for the answer alone 400s.
-        max_completion_tokens: 512,
-      }),
-      signal: AbortSignal.timeout(options.timeoutMs ?? 20_000),
-    });
+    );
 
     if (!response.ok) {
       // Capped: this lands on the work item's row, and an HTML error page would land there whole.
diff --git a/server/tests/channel-titler.test.ts b/server/tests/channel-titler.test.ts
index 953be3044..60af46751 100644
--- a/server/tests/channel-titler.test.ts
+++ b/server/tests/channel-titler.test.ts
@@ -25,6 +25,7 @@ describe("asking the model for a title", () => {
     const answer = await createChannelTitler({
       model: "gpt-4.1-mini",
       resolveApiKey: async () => "key-123",
+      environment: {},
       fetchImpl,
     })("Asked: which receipts count as travel?");
 
@@ -33,6 +34,43 @@ describe("asking the model for a title", () => {
     expect(calls[0]?.body.model).toBe("gpt-4.1-mini");
   });
 
+  test("asks the endpoint OPENAI_BASE_URL names, not OpenAI", async () => {
+    const { calls, fetchImpl } = respondWith({
+      choices: [{ message: { content: "Travel receipt rules" } }],
+    });
+
+    await createChannelTitler({
+      model: "openai/gpt-5.6-terra",
+      resolveApiKey: async () => "gateway-key",
+      environment: { OPENAI_BASE_URL: "https://gateway.internal/v1" },
+      fetchImpl,
+    })("Asked: which receipts count as travel?");
+
+    expect(calls.map((call) => call.url)).toEqual([
+      "https://gateway.internal/v1/chat/completions",
+    ]);
+  });
+
+  test("reads OPENAI_BASE_URL from the process when no environment is passed", async () => {
+    const { calls, fetchImpl } = respondWith({
+      choices: [{ message: { content: "Travel receipt rules" } }],
+    });
+    const previous = process.env.OPENAI_BASE_URL;
+    process.env.OPENAI_BASE_URL = "http://localhost:4010";
+    try {
+      await createChannelTitler({
+        model: "gpt-4.1-mini",
+        resolveApiKey: async () => "gateway-key",
+        fetchImpl,
+      })("Asked: anything?");
+    } finally {
+      if (previous === undefined) delete process.env.OPENAI_BASE_URL;
+      else process.env.OPENAI_BASE_URL = previous;
+    }
+
+    expect(calls[0]?.url).toBe("http://localhost:4010/v1/chat/completions");
+  });
+
   test("asks nothing at all when the deployment has no key", async () => {
     const { calls, fetchImpl } = respondWith({});