All Mistral models fail with ZodError: "finish" expected string, received object

Description

All Mistral provider models fail with a ZodError validation error after successfully generating a response. The error occurs during stream parsing when the AI SDK validates the finish field.

Steps to Reproduce

# Any Mistral model fails:
opencode run -m mistral/ministral-3b-latest "say hi" < /dev/null
opencode run -m mistral/mistral-small-latest "say hi" < /dev/null
opencode run -m mistral/mistral-large-latest "say hi" < /dev/null

Expected Behavior

Command completes successfully after generating response.

Actual Behavior

Response generates correctly, then immediately fails with validation error:

ZodError: [
  {
    "expected": "string",
    "code": "invalid_type",
    "path": ["finish"],
    "message": "Invalid input: expected string, received object"
  }
]

Full error with --format json:

{"type":"text","timestamp":...,"part":{"type":"text","text":"Hi"}}
{"type":"error","timestamp":...,"error":{"name":"UnknownError","data":{"message":"[{\"code\":\"invalid_union\",\"errors\":[[{\"expected\":\"string\",\"code\":\"invalid_type\",\"path\":[\"reason\"],\"message\":\"Invalid input: expected string, received object\"}],...]}"}}}

Root Cause Analysis

The Vercel AI SDK expects the Mistral stream to return {"finish": "stop"} (string), but Mistral's API returns {"finish": {"reason": "stop"}} (object). This causes Zod validation to fail.

Environment

OpenCode version: 1.0.186
OS: Linux (Debian 12)
Installation method: curl
Affected models: All mistral/* models

Related Issues

generateObject and streamObject not working after v5 update for Mistral models vercel/ai#8119 - Similar Mistral validation issue (fixed for generateObject)
imagen_generate tool crashes with validation error: expected string, received object #4951 - Similar "expected string, received object" pattern

This appears to be a unique issue specific to Mistral's API response format for the stream finish field.

While there is a related issue #5034 about Ministral 3 support, that issue addresses a different error (system message role error) rather than the ZodError validation issue with the finish field.

This issue is distinct from other provider validation errors in the codebase, as it specifically stems from Mistral's API returning {"finish": {"reason": "stop"}} (object) while the Vercel AI SDK expects {"finish": "stop"} (string).

Recommendation: This appears to be a fresh/unique issue that may require a custom Mistral provider adapter or upstream fix in the Vercel AI SDK's Mistral integration.

I am also facing this error also for GROQ related models. I am using gpt oss 120b with groq and its not working on opencode.

me too all groq models fails too.

can anyone show me:

cat ~/.cache/opencode/package.json

looks like ai sdk v6 released just now and it busts the cached versions, looking into fix

not sure if you still need it but here you go:

╭╴󰀵 // ima // [main]
╰─> cat ~/.cache/opencode/package.json
{
  "dependencies": {
    "oh-my-opencode": "2.4.5",
    "opencode-antigravity-auth": "1.1.2",
    "@tarquinen/opencode-dcp": "1.0.4",
    "@franlol/opencode-md-table-formatter": "0.0.3",
    "opencode-copilot-auth": "0.0.9",
    "opencode-anthropic-auth": "0.0.5",
    "@ai-sdk/gateway": "3.0.0"
  }
}

Will release fix shortly:
https://github.com/sst/opencode/commits/dev/

I think this should get it fixed

ty goat 👑

Release is in progress. w/ desktpp stuff it takes a while and some of the npm stuff is getting 503'ed so im doing waht I can but blocked until release goes out :/

welp:
https://www.githubstatus.com/

now github is down

after 3 yrs of waiting it finally deployed. Latest should have fix

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All Mistral models fail with ZodError: "finish" expected string, received object #5981

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All Mistral models fail with ZodError: "finish" expected string, received object #5981

Description

Description

Steps to Reproduce

Expected Behavior

Actual Behavior

Root Cause Analysis

Environment

Related Issues

Activity

github-actions commented on Dec 22, 2025

nimitbhardwaj commented on Dec 22, 2025

Vicenzo-Giuseppe commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

rayhanadev commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

rayhanadev commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

rekram1-node commented on Dec 22, 2025

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