Recursive $ref in postgres tool schemas breaks Meta Muse Spark ("Recursive JSON schemas are not currently supported") #45800

Description

Summary

Using Muse Spark 1.2 Contributor via OpenCode Go (paid subscription) fails immediately with:
_

AI_APICallError: Error from provider (Console Go): Upstream request failed:
[invalid_request_error] Recursive JSON schemas are not currently supported

_
The error occurs on the first request before any tool executes. The cause is the PostgreSQL tool schemas (postgres-readonly_pg_explain, postgres-readonly_pg_readonly, postgres-readonly_pg_query) which contain a self-referencing $ref:

{
  "$defs": {
    "__schema0": {
      "anyOf": [
        {"type": "string"},
        {"type": "number"},
        {"type": "boolean"},
        {"type": "null"},
        {"type": "array", "items": {"$ref": "#/$defs/__schema0"}},
        {"type": "object", "additionalProperties": {"$ref": "#/$defs/__schema0"}}
      ]
    }
  }
}

Meta's Model API explicitly rejects recursive schemas (https://ai.developer.meta.com/docs/features/structured-output/) in tool parameters with HTTP 400.

Why it happens

packages/opencode/src/provider/transform.ts has per-provider schema sanitizers for OpenAI, Moonshot/Kimi, and Gemini — but no Meta/Muse-specific sanitization. The sanitizeOpenAISchema function (which applies to Meta via @ai-sdk/openai) preserves $ref/$defs verbatim, so recursive schemas pass through to Meta's API unchanged.

Suggested fix

Flatten recursive $ref cycles in the schema transform layer before sending to any provider that rejects them. The approach from unmerged PR #29295 (inline local $refs, replace recursive refs with permissive {}) or the merged MCP fix #16910 (fallback to {type:"object", additionalProperties:true}) would both work.

Workaround

Disable PostgreSQL tools in opencode.json:

{
  "permission": {
    "postgres-*": "deny"
  }
}

Environment

• opencode: latest (2026-08-28) 1.18.23
• Provider: opencode-go → Console Go → Meta Model API
• Model: muse-spark-1.2-contributor
• OS: Linux (Pop! OS 24.04)

Plugins

None

OpenCode version

1.18.23

Steps to reproduce

1. opencode.json - define a local mcp server

  "mcp": {
    "postgres-readonly": {
      "type": "local",
      "enabled": true,
      "command": ["npx", "-y", "@yawlabs/postgres-mcp@latest"],
      "environment": {
        "DATABASE_URL": "postgresql://testuser:<TESTPASSWD>@localhost:5432/TESTDB",
        "ALLOW_WRITES": "0"
      }
    }
  }

2. opencode.json - set permissions

"permission": {
  "postgres-readonly_*": "allow"
}

3. Start opencode
4. set model to Muse Spark 1.2 Contributor
5. Type 'Hello'
6. response should fail in a few seconds with

Error from provider (Console Go): Upstream request failed: [invalid_request_error] Recursive JSON schemas are not currently supported

7. (Side note) setting MCP tool "enabled": false, and repeat steps 3 - 5, should result in a successful response.

Screenshot and/or share link

No response

Operating System

Linux (Pop! OS 24.04)

Terminal

COSMIC Terminal