openclaw - 💡(How to fix) Fix fix: normalizeDeepSeekSchema drops all but first anyOf variant for const unions [5 pull requests]

Bug Description

normalizeDeepSeekSchema in src/plugin-sdk/provider-tools.ts collapses anyOf unions of const literals to only the first variant. This makes multi-option tool parameters (like mode with 7 enum values) appear as a single const to the LLM, causing validation errors when the model tries to use any option other than the first.

Root Cause

In normalizeDeepSeekSchema() (line ~498 of the bundled provider-tools file):

const selected = nonNullVariants[0] ?? normalizedVariants[0];
const merged = { ...selected, ...normalized };

When a property has anyOf: [{const:"A"}, {const:"B"}, ..., {const:"G"}] (7 const literals from Typebox Union[Literal]), the function:

1. Skips copying the anyOf key (line 485-489)
2. Takes only nonNullVariants[0] — the first const value
3. Merges it with remaining properties

Result: The LLM sees {const: "A", type: "string", description: "..."} instead of {anyOf: [{const:"A"}, ..., {const:"G"}]}.

The function was designed to handle nullable unions (e.g. {anyOf: [{type:"string"}, {type:"null"}]} → {type:"string", nullable:true}), but incorrectly applies the same "pick first" logic to unions of string literal consts.

Reproduction

Any plugin tool with a Type.Union([Type.Literal("a"), Type.Literal("b"), ...]) parameter, used with a DeepSeek model.

Concrete example: The openclaw-lark plugin's feishu_update_doc tool defines:

mode: Type.Union([
  Type.Literal("overwrite"),
  Type.Literal("append"),
  Type.Literal("replace_range"),
  Type.Literal("replace_all"),
  Type.Literal("insert_before"),
  Type.Literal("insert_after"),
  Type.Literal("delete_range"),
], { description: '更新模式（必填）' })

Typebox correctly generates:

{"anyOf": [{"const":"overwrite","type":"string"}, {"const":"append","type":"string"}, ...]}

But after normalizeDeepSeekSchema, the LLM only sees:

{"const": "overwrite", "type": "string", "description": "更新模式（必填）"}

All 6 other modes (append, replace_range, replace_all, insert_before, insert_after, delete_range) are invisible to the model.

Impact

• Tool parameters using Union[Literal] (Typebox) or equivalent JSON Schema anyOf with const values are silently broken for DeepSeek models
• Models can only use the first enum value; all others cause Validation failed: mode: must be equal to constant
• The same issue affects any plugin that uses const unions for enum-like parameters

Suggested Fix

When all non-null variants are const string literals, convert to enum instead of picking the first:

// In normalizeDeepSeekSchema, after computing nonNullVariants:
const allConstStrings = nonNullVariants.every(
  v => v && typeof v === "object" && "const" in v && typeof v.const === "string"
);
if (allConstStrings) {
  const enumValues = nonNullVariants.map(v => v.const);
  return {
    type: "string",
    enum: enumValues,
    ...normalized  // preserve description, etc.
  };
}
// ... existing nullable union handling

This preserves the full set of allowed values while staying compatible with DeepSeek (which supports enum in JSON Schema).

Environment

• OpenClaw version: 2026.5.20
• Model: deepseek-v4-flash (via openai-completions API)
• Plugin: openclaw-lark (feishu_update_doc tool)