Summary

When using oh-my-opencode with opencode v1.2.6, the process crashes with a TypeError in certain conditions — specifically when a model calls the task() tool without providing subagent_type.

This is primarily an opencode bug, but it's worth noting here because oh-my-opencode's multi-model orchestration (especially Sisyphus with models like Qwen 3.5, GLM-4.7) increases the frequency of task() calls, making the crash more likely to surface.

The Error

TypeError: undefined is not an object (evaluating 'str3.replace')
      at titlecase (src/util/locale.ts:3:12)
      at task (src/cli/cmd/run.ts:170:24)
      at loop (src/cli/cmd/run.ts:472:15)

What Triggers It

opencode/run.ts:170 calls Locale.titlecase(info.input.subagent_type) with no null check. When a model omits subagent_type from its task() call (valid per schema), titlecase(undefined) throws.

In TypeScript project directories, models orchestrated by oh-my-opencode's Sisyphus agent tend to delegate via task() more aggressively, often without subagent_type — reliably reproducing the crash.

Attempted Workaround: disabled_hooks

Adding "disabled_hooks": ["category-skill-reminder"] to oh-my-opencode.json does not fully fix this — even with the hook disabled, the models themselves generate task() calls without subagent_type. The hook was only one trigger.

Upstream Issue

Filed as: anomalyco/opencode#14169

The fix is a simple null guard in src/util/locale.ts:

function titlecase(str: string | undefined): string {
    if (!str) return "";
    return str.replace(/\b\w/g, (c) => c.toUpperCase());
}

Workaround Until Fixed

A same-size binary patch can be applied to the compiled opencode binary. Full details, patch script, and verification results here:

https://gist.github.com/bkataru/27caa1aeb746efb06f83127cfcc586b0

Suggestion for oh-my-opencode

If possible, when oh-my-opencode generates a task() call (e.g. via the category-skill-reminder hook or Sisyphus orchestration), ensuring subagent_type is always included would prevent this crash path regardless of the opencode version.

Environment