Bug: Zod TypeError when loading custom tools from .opencode directory #12336

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1. github-actions

   assigned

   rekram1-node

   on Feb 5, 2026
2. github-actions

   added

   windows

   on Feb 5, 2026
3. github-actions commented on Feb 5, 2026

   

   github-actionsBot

   on Feb 5, 2026 – with GitHub Actions

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   This issue might be a duplicate of existing issues. Please check:

   • bug: tool.registry test fails on CI — custom tool import crashes registry when dependencies are missing #12269: Tool registry test fails on CI — custom tool import crashes registry when dependencies are missing (same root cause location with missing error handling for custom tool imports)
   • Bug: TypeError in session prompt handling and workflow timeout with free models #9733: TypeError in session prompt handling with similar undefined object access pattern in src/session/prompt.ts

   Feel free to ignore if none of these address your specific case.
4. wlioi commented on Feb 5, 2026

   

   wlioi

   on Feb 5, 2026

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   @github-actions[bot] This is not a duplicate of the mentioned issues.

   Comparison with suggested issues

   Our issue (#12336)

   • Location: src/session/prompt.ts:704:62
   • Error: TypeError: undefined is not an object (evaluating 'schema._zod.def')
   • Root cause: Zod 4.1.8 toJSONSchema function lacks defensive checks when processing tool parameter schemas
   • Trigger: Loading custom tools from .opencode directory

   #12269

   • Issue: Tool dependency import fails registry
   • Root cause: Missing error handling in ToolRegistry.state() when importing tools with unresolvable dependencies
   • Different: This is about dependency resolution, not Zod schema validation

   #9733

   • Location: src/session/prompt.ts:1597
   • Error: TypeError: undefined is not an object (evaluating 'command3.agent')
   • Root cause: command3.agent is undefined (null checking issue)
   • Different: This is about command handling, not Zod schema validation

   Conclusion

   This is a separate bug that needs its own fix. The commonality is that all three are TypeError issues in the same file, but they have different root causes and occur at different locations.

   Please reopen this issue.
5. rekram1-node commented on Feb 5, 2026

   

   rekram1-node

   on Feb 5, 2026

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   can u send ur custom tools?
6. wlioi commented on Feb 5, 2026

   

   wlioi

   on Feb 5, 2026

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   @wlioi Yes! The minimal reproduction is:

   This triggers the Zod TypeError in toJSONSchema when processing the nested ZodString.
7. wlioi commented on Feb 5, 2026

   

   wlioi

   on Feb 5, 2026

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   @rekram1-node Apologies for the confusion! Here's the actual minimal reproduction code that triggers the bug:

   Minimal Reproduction

   The bug occurs when your custom tool returns a plain object instead of a Zod schema in the args field. Here's what triggers it:

   // tools/test-tool.js
   const { z } = require('zod');
   
   function createBrokenTool(description) {
     const safeArgs = z.object({
       name: z.string().describe("A name parameter")
     });
   
     // BUG: Returning safeArgs._zod.def (plain object) instead of safeArgs (Zod schema)
     return {
       description,
       args: safeArgs._zod.def,  // This causes the TypeError!
       execute: async (args) => `Hello ${args.name}!`
     };
   }
   
   module.exports = {
     testTool: createBrokenTool("Test tool")
   };

   Why This Fails

   1. safeArgs._zod.def returns a plain object like { shape: { name: ZodString } }
   2. OpenCode's toJSONSchema() expects a Zod schema with _zod property
   3. When it tries to access schema._zod.def, schema._zod is undefined
   4. Result: TypeError: undefined is not an object (evaluating 'schema._zod.def')

   The fix should be in OpenCode's to-json-schema.ts to handle cases where schema._zod is undefined.
8. github-actions commented on Apr 7, 2026

   

   github-actionsBot

   on Apr 7, 2026 – with GitHub Actions

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   To stay organized issues are automatically closed after 90 days of no activity. If the issue is still relevant please open a new one.
9. github-actions

   closed this as completedon Apr 7, 2026