diff --git a/packages/server/src/server/agent/agent-manager.ts b/packages/server/src/server/agent/agent-manager.ts
index 5681d8e636..f3beed5d27 100644
--- a/packages/server/src/server/agent/agent-manager.ts
+++ b/packages/server/src/server/agent/agent-manager.ts
@@ -2323,9 +2323,18 @@ export class AgentManager {
    * `settings.features` sends composer values as `featureValues`; this is where they become an
    * options patch for the agent's provider.
    */
-  async setAgentFeatureValues(agentId: string, values: Record<string, unknown>): Promise<void> {
+  async setAgentFeatureValues(input: {
+    agentId: string;
+    values: Record<string, unknown>;
+    /** Options sent with the values; they win over a value of the same name. */
+    options?: Record<string, unknown>;
+  }): Promise<void> {
+    const { agentId, values, options } = input;
     const provider = this.requireAgent(agentId).provider;
-    await this.setAgentOptions(agentId, convertLegacyOptions({ provider, options: values }));
+    await this.setAgentOptions(agentId, {
+      ...convertLegacyOptions({ provider, options: values }),
+      ...options,
+    });
   }
 
   /** The config as the opened session left it: its own difference from the options it was given. */
diff --git a/packages/server/src/server/agent/mcp-server.test.ts b/packages/server/src/server/agent/mcp-server.test.ts
index 1d24d942e9..de878bcde0 100644
--- a/packages/server/src/server/agent/mcp-server.test.ts
+++ b/packages/server/src/server/agent/mcp-server.test.ts
@@ -4718,8 +4718,9 @@ describe("update_agent MCP tool", () => {
     expect(spies.agentManager.setAgentMode).toHaveBeenCalledWith("agent-1", "full-access");
     expect(spies.agentManager.setAgentModel).toHaveBeenCalledWith("agent-1", "gpt-5.4");
     expect(spies.agentManager.setAgentThinkingOption).toHaveBeenCalledWith("agent-1", "high");
-    expect(spies.agentManager.setAgentFeatureValues).toHaveBeenCalledWith("agent-1", {
-      fast_mode: true,
+    expect(spies.agentManager.setAgentFeatureValues).toHaveBeenCalledWith({
+      agentId: "agent-1",
+      values: { fast_mode: true },
     });
     expect(spies.agentManager.updateAgentMetadata).toHaveBeenCalledWith("agent-1", {
       title: "Updated agent",
diff --git a/packages/server/src/server/agent/option-controls.test.ts b/packages/server/src/server/agent/option-controls.test.ts
index 7e3198d00f..c9d7a88bbc 100644
--- a/packages/server/src/server/agent/option-controls.test.ts
+++ b/packages/server/src/server/agent/option-controls.test.ts
@@ -49,4 +49,17 @@ describe("legacy Codex Fast at the other entry points", () => {
       service_tier: "fast",
     });
   });
+
+  test("a hook that replaces the speed it was sent with fast_mode selects Fast", () => {
+    const sent = {
+      provider: "codex",
+      providerOptions: { service_tier: "default" },
+      featureValues: { service_tier: "default" },
+    };
+    const returned = { ...sent, featureValues: { fast_mode: true } };
+
+    expect(foldHookFeatureValues({ returned, sent }).providerOptions).toEqual({
+      service_tier: "fast",
+    });
+  });
 });
diff --git a/packages/server/src/server/agent/option-controls.ts b/packages/server/src/server/agent/option-controls.ts
index 846b840233..2bbb1a1e6a 100644
--- a/packages/server/src/server/agent/option-controls.ts
+++ b/packages/server/src/server/agent/option-controls.ts
@@ -111,7 +111,9 @@ export function foldHookFeatureValues<
     // No copy was sent, so everything the hook put in `featureValues` is new.
     return foldFeatureValues({ config: returned, provider: returned.provider });
   }
-  const after = featureValues ?? {};
+  // The copy the hook was sent is canonical; what it returns may name the old key, so both
+  // sides are compared in the same form and a replaced speed is not read as a deletion.
+  const after = convertLegacyOptions({ provider: returned.provider, options: featureValues ?? {} });
   const patch: ProviderOptionsPatch = {};
   for (const key of new Set([...Object.keys(before), ...Object.keys(after)])) {
     if (isDeepStrictEqual(after[key], before[key])) continue;
@@ -124,7 +126,7 @@ export function foldHookFeatureValues<
         provider: returned.provider,
         options: rest.providerOptions ?? undefined,
       }),
-      patch: convertLegacyOptions({ provider: returned.provider, options: patch }),
+      patch,
     }),
   };
 }
diff --git a/packages/server/src/server/agent/providers/codex-app-server-agent.features.test.ts b/packages/server/src/server/agent/providers/codex-app-server-agent.features.test.ts
index 292130b1f1..1857fa7ba5 100644
--- a/packages/server/src/server/agent/providers/codex-app-server-agent.features.test.ts
+++ b/packages/server/src/server/agent/providers/codex-app-server-agent.features.test.ts
@@ -797,7 +797,7 @@ describe("Codex app-server provider controls", () => {
       const agentId = await create();
       expect(shownSpeed(agentId).selected).toBe("default");
 
-      await manager.setAgentFeatureValues(agentId, { fast_mode: true });
+      await manager.setAgentFeatureValues({ agentId, values: { fast_mode: true } });
       expect(shownSpeed(agentId)).toMatchObject({ own: { service_tier: "priority" }, ...FAST });
       await runTurn(agentId, "priority");
 
@@ -818,7 +818,24 @@ describe("Codex app-server provider controls", () => {
       const { manager, create, shownSpeed, runTurn } = createLegacyFastHarness();
       const agentId = await create({ service_tier: "priority" });
 
-      await manager.setAgentFeatureValues(agentId, { service_tier: "default", fast_mode: true });
+      await manager.setAgentFeatureValues({
+        agentId,
+        values: { service_tier: "default", fast_mode: true },
+      });
+
+      expect(shownSpeed(agentId)).toMatchObject({ own: { service_tier: "default" } });
+      await runTurn(agentId, "default");
+    });
+
+    test("options sent with the older values replace them before anything is applied", async () => {
+      const { manager, create, shownSpeed, runTurn } = createLegacyFastHarness();
+      const agentId = await create({ service_tier: "priority" });
+
+      await manager.setAgentFeatureValues({
+        agentId,
+        values: { service_tier: "retired-tier" },
+        options: { service_tier: "default" },
+      });
 
       expect(shownSpeed(agentId)).toMatchObject({ own: { service_tier: "default" } });
       await runTurn(agentId, "default");
@@ -828,7 +845,7 @@ describe("Codex app-server provider controls", () => {
       const { manager, create, shownSpeed, runTurn } = createLegacyFastHarness();
       const agentId = await create({ service_tier: "priority" });
 
-      await manager.setAgentFeatureValues(agentId, { fast_mode: false });
+      await manager.setAgentFeatureValues({ agentId, values: { fast_mode: false } });
 
       expect(shownSpeed(agentId)).toMatchObject({ own: { service_tier: "default" } });
       await runTurn(agentId, "default");
diff --git a/packages/server/src/server/agent/tools/paseo-tools.ts b/packages/server/src/server/agent/tools/paseo-tools.ts
index 4e40c9b249..f83d982ac8 100644
--- a/packages/server/src/server/agent/tools/paseo-tools.ts
+++ b/packages/server/src/server/agent/tools/paseo-tools.ts
@@ -2292,7 +2292,7 @@ function createToolCatalog(
         await agentManager.setAgentThinkingOption(agentId, settings.thinkingOptionId);
       }
       if (settings?.features) {
-        await agentManager.setAgentFeatureValues(agentId, settings.features);
+        await agentManager.setAgentFeatureValues({ agentId, values: settings.features });
       }
 
       await updateAgentCommand({ agentManager }, { agentId, name, labels });
diff --git a/packages/server/src/server/session.ts b/packages/server/src/server/session.ts
index 26f6cd5614..927db78077 100644
--- a/packages/server/src/server/session.ts
+++ b/packages/server/src/server/session.ts
@@ -1067,7 +1067,7 @@ export class Session {
           (await setAgentModeCommand({ agentManager }, { agentId, modeId })).notice,
         setModel: (agentId, modelId) => agentManager.setAgentModel(agentId, modelId),
         setOptions: (agentId, patch) => agentManager.setAgentOptions(agentId, patch),
-        setFeatureValues: (agentId, values) => agentManager.setAgentFeatureValues(agentId, values),
+        setFeatureValues: (input) => agentManager.setAgentFeatureValues(input),
         setThinking: (agentId, thinkingOptionId) =>
           agentManager.setAgentThinkingOption(agentId, thinkingOptionId),
       },
diff --git a/packages/server/src/server/session/agent-config/agent-config-session.test.ts b/packages/server/src/server/session/agent-config/agent-config-session.test.ts
index 084cfcbe45..a9869f0118 100644
--- a/packages/server/src/server/session/agent-config/agent-config-session.test.ts
+++ b/packages/server/src/server/session/agent-config/agent-config-session.test.ts
@@ -13,7 +13,11 @@ class FakeAgentConfigOperations implements AgentConfigOperations {
   readonly modeCalls: Array<{ agentId: string; modeId: string }> = [];
   readonly modelCalls: Array<{ agentId: string; modelId: string | null }> = [];
   readonly optionsCalls: Array<{ agentId: string; patch: Record<string, unknown> }> = [];
-  readonly featureValueCalls: Array<{ agentId: string; values: Record<string, unknown> }> = [];
+  readonly featureValueCalls: Array<{
+    agentId: string;
+    values: Record<string, unknown>;
+    options?: Record<string, unknown>;
+  }> = [];
   readonly thinkingCalls: Array<{ agentId: string; thinkingOptionId: string | null }> = [];
   /** Cross-operation ordering, which the per-operation arrays above cannot show. */
   readonly callLog: string[] = [];
@@ -46,8 +50,12 @@ class FakeAgentConfigOperations implements AgentConfigOperations {
     if (this.failWith) throw this.failWith;
   }
 
-  async setFeatureValues(agentId: string, values: Record<string, unknown>): Promise<void> {
-    this.featureValueCalls.push({ agentId, values });
+  async setFeatureValues(input: {
+    agentId: string;
+    values: Record<string, unknown>;
+    options?: Record<string, unknown>;
+  }): Promise<void> {
+    this.featureValueCalls.push(input);
     this.callLog.push("featureValues");
     if (this.failWith) throw this.failWith;
   }
@@ -366,7 +374,7 @@ describe("AgentConfigSession", () => {
     ]);
   });
 
-  test("apply: legacy featureValues are applied first and options after, so options win", async () => {
+  test("apply: legacy featureValues and options go in one call, options winning", async () => {
     const { subsystem, operations } = makeSubsystem();
 
     await subsystem.handleAgentConfigApplyRequest({
@@ -379,11 +387,14 @@ describe("AgentConfigSession", () => {
       requestId: "req-1",
     });
 
-    expect(operations.callLog).toEqual(["featureValues", "options"]);
+    expect(operations.callLog).toEqual(["featureValues"]);
     expect(operations.featureValueCalls).toEqual([
-      { agentId: "agent-1", values: { fast_mode: true, service_tier: "fast" } },
+      {
+        agentId: "agent-1",
+        values: { fast_mode: true, service_tier: "fast" },
+        options: { fast_mode: false },
+      },
     ]);
-    expect(operations.optionsCalls).toEqual([{ agentId: "agent-1", patch: { fast_mode: false } }]);
   });
 
   test("apply: leaves omitted fields alone", async () => {
diff --git a/packages/server/src/server/session/agent-config/agent-config-session.ts b/packages/server/src/server/session/agent-config/agent-config-session.ts
index 9f857a1103..db471c111f 100644
--- a/packages/server/src/server/session/agent-config/agent-config-session.ts
+++ b/packages/server/src/server/session/agent-config/agent-config-session.ts
@@ -31,7 +31,11 @@ export interface AgentConfigOperations {
   setModel(agentId: string, modelId: string | null): Promise<void>;
   setOptions(agentId: string, patch: ProviderOptionsPatch): Promise<void>;
   /** COMPAT(featureValues): added in v0.15.0, remove after 2027-05-01. Older clients' values. */
-  setFeatureValues(agentId: string, values: Record<string, unknown>): Promise<void>;
+  setFeatureValues(input: {
+    agentId: string;
+    values: Record<string, unknown>;
+    options?: ProviderOptionsPatch;
+  }): Promise<void>;
   setThinking(
     agentId: string,
     thinkingOptionId: string | null,
@@ -117,7 +121,7 @@ export class AgentConfigSession {
       failureText: "Failed to set agent feature",
       // COMPAT(featureValues): added in v0.15.0, remove after 2027-05-01. A feature is a one-key options patch.
       run: async () => {
-        await this.operations.setFeatureValues(agentId, { [featureId]: value });
+        await this.operations.setFeatureValues({ agentId, values: { [featureId]: value } });
         return undefined;
       },
       emitResponse: (payload) => this.host.emit({ type: "set_agent_feature_response", payload }),
@@ -194,11 +198,16 @@ export class AgentConfigSession {
       notice ??= thinkingNotice;
     }
     // COMPAT(featureValues): added in v0.15.0, remove after 2027-05-01. `featureValues` is an options patch.
-    if (config.featureValues && Object.keys(config.featureValues).length > 0) {
-      await this.operations.setFeatureValues(agentId, config.featureValues);
-    }
-    if (config.options && Object.keys(config.options).length > 0) {
-      await this.operations.setOptions(agentId, config.options);
+    const hasValues = config.featureValues && Object.keys(config.featureValues).length > 0;
+    const hasOptions = config.options && Object.keys(config.options).length > 0;
+    if (hasValues) {
+      await this.operations.setFeatureValues({
+        agentId,
+        values: config.featureValues ?? {},
+        options: config.options,
+      });
+    } else if (hasOptions) {
+      await this.operations.setOptions(agentId, config.options ?? {});
     }
 
     return notice;