fix(inference): request a reply budget hosted endpoints accept

src/lib/actions/sandbox/rebuild-inference-preflight.test.ts

@@ -68,21 +68,53 @@ describe("atomic rebuild inference preflight", () => {
     const command = buildRebuildInferenceProbeCommand({ ...input, model: "gpt-5.4" });
 
     expect(command).toContain("https://inference.local/v1/chat/completions");
-    expect(command).toContain('"max_completion_tokens":8');
+    expect(command).toContain('"max_completion_tokens":16');
     expect(command).not.toContain('"max_tokens"');
   });
 
   it("sends max_completion_tokens for an o-series model on the chat completions route", () => {
     const command = buildRebuildInferenceProbeCommand({ ...input, model: "o3-mini" });
 
-    expect(command).toContain('"max_completion_tokens":8');
+    expect(command).toContain('"max_completion_tokens":16');
     expect(command).not.toContain('"max_tokens"');
   });
 
   it("keeps max_tokens for a model that supports the legacy chat completions field", () => {
     const command = buildRebuildInferenceProbeCommand({ ...input, model: "nvidia/nemotron" });
 
-    expect(command).toContain('"max_tokens":8');
+    expect(command).toContain('"max_tokens":16');
     expect(command).not.toContain('"max_completion_tokens"');
   });
+
+  it("sends max_output_tokens on the responses route", () => {
+    const command = buildRebuildInferenceProbeCommand({
+      ...input,
+      preferredInferenceApi: "openai-responses",
+    });
+
+    expect(command).toContain("https://inference.local/v1/responses");
+    expect(command).toContain('"max_output_tokens":16');
+  });
+
+  // A hosted endpoint validates the reply budget it is sent, so a budget below
+  // its floor fails a route that normal inference serves. Every preflight route
+  // must clear the floor, not just the one the reporter exercised (#7939).
+  it.each([
+    ["chat completions", "nvidia/nemotron", "openai-completions", "max_tokens"],
+    ["chat completions reasoning", "gpt-5.4", "openai-completions", "max_completion_tokens"],
+    ["responses", "nvidia/nemotron", "openai-responses", "max_output_tokens"],
+    ["anthropic messages", "claude-sonnet-4-6", "anthropic-messages", "max_tokens"],
+  ])("requests a reply budget the endpoint accepts on the %s route (#7939)", (_route, model, preferredInferenceApi, field) => {
+    const endpointMinimumReplyTokens = 16;
+    const command = buildRebuildInferenceProbeCommand({
+      ...input,
+      model,
+      preferredInferenceApi,
+    });
+
+    const budget = new RegExp(`"${field}":(\\d+)`).exec(command);
+
+    expect(budget).not.toBeNull();
+    expect(Number(budget?.[1])).toBeGreaterThanOrEqual(endpointMinimumReplyTokens);
+  });
 });

src/lib/actions/sandbox/rebuild-inference-preflight.ts

@@ -2,7 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 import { getSandboxInferenceConfig } from "../../inference/config";
-import { resolveMaxTokensField } from "../../inference/max-tokens-field";
+import { MIN_PROBE_REPLY_TOKENS, resolveMaxTokensField } from "../../inference/max-tokens-field";
 import { shellQuote } from "../../runner";
 import { executeSandboxExecCommand, type SandboxCommandResult } from "./process-recovery";
 
@@ -35,7 +35,7 @@ function buildProbeRequest(input: RebuildInferencePreflightInput): {
       headers: ["anthropic-version: 2023-06-01"],
       payload: {
         model: input.model,
-        max_tokens: 8,
+        max_tokens: MIN_PROBE_REPLY_TOKENS,
         messages: [{ role: "user", content: "Reply with OK" }],
       },
     };
@@ -44,15 +44,19 @@ function buildProbeRequest(input: RebuildInferencePreflightInput): {
     return {
       endpoint: "https://inference.local/v1/responses",
       headers: [],
-      payload: { model: input.model, input: "Reply with OK", max_output_tokens: 8 },
+      payload: {
+        model: input.model,
+        input: "Reply with OK",
+        max_output_tokens: MIN_PROBE_REPLY_TOKENS,
+      },
     };
   }
   return {
     endpoint: "https://inference.local/v1/chat/completions",
     headers: [],
     payload: {
       model: input.model,
-      [resolveMaxTokensField(input.model)]: 8,
+      [resolveMaxTokensField(input.model)]: MIN_PROBE_REPLY_TOKENS,
       messages: [{ role: "user", content: "Reply with OK" }],
       stream: false,
     },

src/lib/inference/health.test.ts

@@ -112,7 +112,7 @@ describe("inference health", () => {
       expect(payload).toEqual({
         model: "gpt-4o-mini",
         messages: [{ role: "user", content: "Reply with exactly: OK" }],
-        max_tokens: 8,
+        max_tokens: 16,
       });
     });
 
@@ -228,7 +228,7 @@ describe("inference health", () => {
       expect(payload).toEqual({
         model: "moonshotai/kimi-k2.6",
         messages: [{ role: "user", content: "Reply with exactly: OK" }],
-        max_tokens: 8,
+        max_tokens: 16,
         chat_template_kwargs: { thinking: false },
       });
       expect(curlArgValue(capturedArgv, "--connect-timeout")).toBe("3");
@@ -250,7 +250,7 @@ describe("inference health", () => {
       expect(curlArgValue(capturedArgv, "--connect-timeout")).toBe("3");
       expect(curlArgValue(capturedArgv, "--max-time")).toBe("5");
       const payload = JSON.parse(capturedArgv[capturedArgv.indexOf("-d") + 1]);
-      expect(payload).toMatchObject({ max_tokens: 8, stream: true });
+      expect(payload).toMatchObject({ max_tokens: 16, stream: true });
     });
 
     it.each([
@@ -423,7 +423,7 @@ describe("inference health", () => {
       const payload = JSON.parse(capturedArgv[capturedArgv.indexOf("-d") + 1]);
       expect(payload).toEqual({
         model: "claude-sonnet-4-6",
-        max_tokens: 8,
+        max_tokens: 16,
         messages: [{ role: "user", content: "Reply with exactly: OK" }],
       });
     });

src/lib/inference/health.ts

@@ -16,6 +16,7 @@ import { normalizeCredentialValue, resolveProviderCredential } from "../credenti
 import { getProviderSelectionConfig } from "./config";
 import type { LocalProviderHealthProbeOptions } from "./local";
 import { probeLocalProviderHealth } from "./local";
+import { MIN_PROBE_REPLY_TOKENS } from "./max-tokens-field";
 import { getChatCompletionsProbeCurlArgs } from "./onboard-probes";
 import { BUILD_ENDPOINT_URL } from "./provider-models";
 
@@ -70,7 +71,7 @@ const GEMINI_CHAT_COMPLETIONS_ENDPOINT =
   "https://generativelanguage.googleapis.com/v1beta/openai/chat/completions";
 const ANTHROPIC_MESSAGES_ENDPOINT = "https://api.anthropic.com/v1/messages";
 const ANTHROPIC_VERSION_HEADER = "anthropic-version: 2023-06-01";
-const HEALTH_PROBE_MAX_TOKENS = 8;
+const HEALTH_PROBE_MAX_TOKENS = MIN_PROBE_REPLY_TOKENS;
 const CURL_TIMEOUT_STATUS = 28;
 const NODE_SPAWN_TIMEOUT_STATUS = -110;
 

src/lib/inference/max-tokens-field.ts

@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: Apache-2.0
 
 /**
- * Resolves the OpenAI-compatible Chat Completions reply-budget field name for a
- * given model.
+ * Resolves how an inference probe states its reply budget: the OpenAI-compatible
+ * Chat Completions field name for a given model, and the smallest reply budget
+ * every probe may request.
  *
  * OpenAI's GPT-5 family and the reasoning-model series (o1/o3/o4) reject the
  * legacy `max_tokens` parameter on `/chat/completions` and require
@@ -14,6 +15,20 @@
  * share this single resolver rather than each carrying their own model list.
  */
 
+/**
+ * Smallest reply budget an inference probe may request.
+ *
+ * Probes only need to read back a short acknowledgement, but the budget is a
+ * value the endpoint validates, not just a ceiling NemoClaw applies. Some
+ * supported hosted endpoints reject a budget below 16 with HTTP 400 even when
+ * discovery succeeds and normal inference works, so a smaller value turns a
+ * valid endpoint, model, and credential combination into a failed onboarding,
+ * health, or rebuild preflight check (#7939). The Anthropic Messages probe
+ * already requests 16; every other probe shares that floor here rather than
+ * carrying its own literal.
+ */
+export const MIN_PROBE_REPLY_TOKENS = 16;
+
 // Matched by prefix rather than exact id: Azure OpenAI deployments append
 // version/suffix segments (e.g. "gpt-5.4", "gpt-5.4-turbo") and callers may or
 // may not include a provider prefix ("azure/gpt-5.4").

src/lib/inference/onboard-probes.test.ts

@@ -310,15 +310,15 @@ describe("OpenAI-compatible inference probes", () => {
     expect(getChatCompletionsProbePayload("nvidia/nemotron-3-super-120b-a12b")).toEqual({
       model: "nvidia/nemotron-3-super-120b-a12b",
       messages: [{ role: "user", content: "Reply with exactly: OK" }],
-      max_tokens: 8,
+      max_tokens: 16,
     });
   });
 
   it("bounds the hosted compatible inference probe for the served Nemotron model", () => {
     expect(getChatCompletionsProbePayload("nvidia/nvidia/nemotron-3-ultra")).toEqual({
       model: "nvidia/nvidia/nemotron-3-ultra",
       messages: [{ role: "user", content: "Reply with exactly: OK" }],
-      max_tokens: 8,
+      max_tokens: 16,
     });
   });
 
@@ -327,11 +327,35 @@ describe("OpenAI-compatible inference probes", () => {
       expect(getChatCompletionsProbePayload(model)).toEqual({
         model,
         messages: [{ role: "user", content: "Reply with exactly: OK" }],
-        max_completion_tokens: 8,
+        max_completion_tokens: 16,
       });
     }
   });
 
+  // Some hosted endpoints reject a reply budget below 16 with HTTP 400 even
+  // though discovery succeeds and normal inference works, so a bounded probe
+  // that undershoots that floor fails a valid route. Whichever field a model
+  // uses, the budget must clear the floor (#7939).
+  it("requests a reply budget hosted endpoints accept, in whichever field the model uses (#7939)", () => {
+    const endpointMinimumReplyTokens = 16;
+
+    for (const model of [
+      "nvidia/nemotron-3-super-120b-a12b",
+      "nvidia/nvidia/nemotron-3-ultra",
+      "openai/openai/gpt-5.6-sol",
+      "moonshotai/kimi-k2.6",
+      "deepseek-ai/deepseek-v4-pro",
+      "gpt-5.4",
+      "o3-mini",
+    ]) {
+      const payload = getChatCompletionsProbePayload(model);
+      const budget = payload.max_completion_tokens ?? payload.max_tokens;
+
+      expect(typeof budget, `${model} states a reply budget`).toBe("number");
+      expect(budget, model).toBeGreaterThanOrEqual(endpointMinimumReplyTokens);
+    }
+  });
+
   it("uses an extended validation budget for DeepSeek V4 Flash", () => {
     const args = getChatCompletionsProbeCurlArgs({
       credentialArgs: FAKE_CREDENTIAL_ARGS,
@@ -356,7 +380,7 @@ describe("OpenAI-compatible inference probes", () => {
     expect(getChatCompletionsProbePayload("moonshotai/kimi-k2.6")).toEqual({
       model: "moonshotai/kimi-k2.6",
       messages: [{ role: "user", content: "Reply with exactly: OK" }],
-      max_tokens: 8,
+      max_tokens: 16,
       chat_template_kwargs: { thinking: false },
     });
 

src/lib/inference/openai-probe-models.ts

@@ -1,7 +1,7 @@
 // SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 // SPDX-License-Identifier: Apache-2.0
 
-import { resolveMaxTokensField } from "./max-tokens-field";
+import { MIN_PROBE_REPLY_TOKENS, resolveMaxTokensField } from "./max-tokens-field";
 
 export function isDeepSeekV4ProModel(model: unknown): boolean {
   return String(model || "").toLowerCase() === "deepseek-ai/deepseek-v4-pro";
@@ -16,7 +16,7 @@ export function getChatCompletionsProbePayload(model: string): Record<string, un
   const payload = {
     model,
     messages: [{ role: "user", content: "Reply with exactly: OK" }],
-    [maxTokensField]: 8,
+    [maxTokensField]: MIN_PROBE_REPLY_TOKENS,
   };
 
   if (isDeepSeekV4ProModel(model)) {
@@ -33,7 +33,7 @@ export function getChatCompletionsProbePayload(model: string): Record<string, un
   if (isKimiK26Model(model)) {
     return {
       ...payload,
-      [maxTokensField]: 8,
+      [maxTokensField]: MIN_PROBE_REPLY_TOKENS,
       chat_template_kwargs: { thinking: false },
     };
   }