ZCode Kimi Error Fix: max_tokens Exceeds 32768

Introduction

When integrating kimi-k2.7-code hosted on Volcano Ark into ZCode as an AI coding assistant, developers may encounter immediate request failures once starting conversations. The API endpoint returns a persistent 400 InvalidParameter error triggered by improper max_tokens configuration. This article systematically analyzes the root cause, provides step-by-step remediation procedures, summarizes reusable troubleshooting workflows, and lists token limit specifications for mainstream models on Volcano Ark. The resolution logic can be generalized to other model providers and similar token-limit errors.

1. Problem Background & Error Information Sorting

After connecting Volcano Ark’s Kimi model within ZCode, every chat request fails immediately. The complete error payload returned by the platform is shown below:

The parameter `max_tokens` specified in the request is not valid: integer above maximum value, expected a value <= 32768, but got 64000 instead.
Request id: 021784268499157bdf0d8876ec55e469c432250c926544c1ddd341
Turn execution failed
provider-code=InvalidParameter
model=kimi-k2.7-code
reason=invalid_request status=400 retryable=false

We organize key error attributes clearly:

The critical detail: this error cannot be resolved by request retries. It originates from static configuration mismatch rather than transient network or service instability.

2. Root Cause Analysis

The failure mechanism is straightforward: ZCode reads the limit.output value stored inside its config.json configuration file, and injects this value into API requests as the max_tokens argument when forwarding calls to Volcano Ark.

The default template configuration for kimi-k2.7-code inside ZCode sets output = 64000. However, Volcano Ark enforces a hard upper bound of 32768 on max_tokens for the kimi-k2.7-code model. Any request carrying a value higher than this threshold will be rejected directly with HTTP 400 status.

In short: the output token limit defined locally within the client configuration exceeds the official constraint set by the upstream LLM service provider. When routing multi-model requests, teams can adopt an API gateway such as 4sapi to implement client-side parameter interception, avoiding invalid requests from reaching upstream services.

3. Step-by-step Remediation Process

Step 1: Locate the ZCode global configuration file

Configuration file paths differ across operating systems:

• Windows: C:\Users\<YOUR_USERNAME>\.zcode\v2\config.json
• macOS / Linux: ~/.zcode/v2/config.json

Step 2: Locate Volcano Ark model configuration entry

Open config.json, search for keywords such as 火山方舟, ark, or kimi-k2.7-code to find the corresponding provider configuration node. The structure template is as follows:

{
  "b30f806d-eb1c-40b6-9287-851ea1e3c3c6": {
    "name": "Volcano Ark",
    "kind": "anthropic",
    "options": {
      "apiKey": "ark-xxxxxxxxxxxxxx",
      "baseURL": "https://ark.cn-beijing.volces.com/api/coding",
      "apiKeyRequired": true
    },
    "source": "custom",
    "models": {}
  }
}

Step 3: Modify the output limit parameter

Find the configuration segment for kimi-k2.7-code, adjust the value of limit.output from 64000 to any integer not exceeding 32768. It is recommended to use 32000 to reserve a safe margin and prevent boundary-triggered exceptions.

"kimi-k2.7-code": {
  "limit": {
    "context": 256000,
    "output": 32000
    // Original value: 64000
  },
  "modalities": {
    "input": ["text"],
    "output": ["text"]
  }
}

Directly assigning 32768 also works in testing; reserving small buffer space is the safer engineering practice.

Step 4: Save changes and fully restart ZCode

1. Save the modified config.json file
2. Completely exit ZCode (terminate background processes, not merely close the window)
3. Launch ZCode again to load updated configurations

Step 5: Function Verification

Re-select model kimi-k2.7-code and initiate a dialogue. Normal response output confirms the fault has been eliminated.

4. Extended Background: Why the Default Template Uses 64000

When users manually add the Volcano Ark provider for the first time, ZCode loads built-in model template parameters. The template sets output:64000, which may reference parameter specifications of other compatible models, or be compiled before Volcano Ark published official parameter constraints for kimi-k2.7-code.

Subsequent divergence between template constants and upstream platform hard limits triggers persistent 400 errors. Manual modification of config.json remains the most direct solution for this template mismatch issue.

5. Universal Troubleshooting Checklist for Token-limit Errors

When integrating any third-party LLM provider with ZCode and encountering 400 errors related to max_tokens or context window limits, follow this standardized workflow:

1. Extract numerical hints from error logs: identify the official ceiling X (expected ≤ X) and the locally configured value Y
2. Navigate to config.json using the corresponding OS file path
3. Locate the path: provider -> models -> [target-model-name] -> limit
4. Adjust output to ≤ X. For context window overflow errors, modify the context field using identical logic
5. Restart ZCode to activate updated configuration

6. Reference Table: Max_tokens Limits for Common Models on Volcano Ark

All values should be cross-checked against official documentation, as platform specifications are subject to iterative adjustment.

7. Conclusion

The root cause of this failure is straightforward: the default output limit value 64000 defined inside ZCode’s kimi-k2.7-code template exceeds Volcano Ark’s hard max_tokens limit of 32768, leading to consistent 400 request rejection.

The remediation workflow consists of editing config.json, reducing the output limit parameter, and restarting the application. More importantly, the troubleshooting routine can be generalized: whenever receiving parameter validation errors indicating token limit overflow, developers should match the threshold described in error messages against local client configuration.

The pattern applies to all models integrated within ZCode. If similar max_tokens or context-length constraint errors appear when switching alternative model providers, engineers can adopt exactly the same investigation and fixing strategy.