Description

Subagent jobs (agent run) fail with schema is not a function across all providers (DeepSeek, OpenAI/Qwen, Anthropic). All other gbrain features (search, sync, extract, dream cycle) work correctly.

Error

[chat(deepseek:deepseek-chat)] schema is not a function. (In 'schema()', 'schema' is an instance of Object)

Same error regardless of provider:

• anthropic:claude-sonnet-4-6 → same
• openai:qwen3.7-max → same

Environment

Root Cause Analysis

The error occurs in the gatewayToolLoop → generateText call path. In src/core/ai/gateway.ts line 2531, tool schemas are constructed as:

inputSchema: { jsonSchema: t.inputSchema } as any

The AI SDK v6 internally calls .schema() on a tool schema object during processing, but the object lacks this method as a callable function. This happens regardless of:

• zod version (tested v3.25.76 with package.json overrides and v4.3.6)
• provider (tested DeepSeek via @ai-sdk/openai-compatible, Qwen via @ai-sdk/openai, Anthropic via @ai-sdk/anthropic)
• run mode (tested both bun build --compile binary and bun run source)
• agent.use_gateway_loop setting (tested both true and false)

The issue appears to be an API mismatch between gbrain's tool schema construction ({ jsonSchema: ... }) and how AI SDK v6.0.174 processes tool schemas internally.

Steps to Reproduce

# On a fresh gbrain v0.42.8.0 install with PostgreSQL engine:
gbrain config set models.tier.subagent deepseek:deepseek-chat
gbrain jobs work --queue default &  # start worker
gbrain jobs submit subagent --params '{"prompt":"reply with exactly: working"}'
sleep 15
gbrain jobs get <id>  # shows DEAD with schema error

What Was Tried (all failed)

1. Upgraded from v0.42.1.0 to v0.42.8.0
2. Clean rm -rf node_modules && bun install
3. Pinned zod to v3.25.76 via package.json overrides
4. Tested compiled binary (bun build --compile)
5. Tested source mode (bun run src/cli.ts)
6. Tested all three provider types
7. Toggled agent.use_gateway_loop
8. Fresh rebuild after each change

Impact

All subagent/agent-run functionality is completely non-functional. Other gbrain features (search, sync, extract, dream cycle, skillopt) operate normally.