fix(log): Resolve 'undefined is not an object (evaluating Log.Default.lazy.info)' error

[konard]

Summary

Fixes #96 - The agent CLI was crashing with the error "undefined is not an object (evaluating 'Log.Default.lazy.info')" when running commands.

Root Cause

The code in `src/index.js` was calling `Log.Default.lazy.info()`, but the `Log.Default` object does not have a `.lazy` property. The lazy logging functionality is built directly into the logging methods themselves (e.g., `Log.Default.info()` already accepts callback functions for lazy evaluation).

Changes

1. Fixed `src/index.js`

   • Changed `Log.Default.lazy.info(...)` to `Log.Default.info(...)`
   • The lazy evaluation is built into the logging methods, not a separate property

2. Added backward compatibility in `src/util/log.ts`

   • Added `lazy` property to Logger type (optional)
   • Added self-referencing `lazy` property to Logger instances: `result.lazy = result`
   • This allows both syntaxes to work: `Log.Default.info()` and `Log.Default.lazy.info()`

3. Added tests in `tests/log-lazy.test.js`

   • Verify `Log.Default.info()` accepts callback functions
   • Verify lazy logging with callbacks works correctly

4. Created case study documentation in `docs/case-studies/issue-96/`

   • Comprehensive analysis of the root cause
   • Timeline of events
   • Lessons learned and prevention strategies

Test Plan

• Run `bun test tests/log-lazy.test.js` - All 19 tests pass
• Verify `echo '{"message":"hi"}' | bun run src/index.js --model link-assistant/echo --no-always-accept-stdin` works without crashing
• Verify `--verbose` mode shows proper JSON log output including "Agent started" message
• CI tests should pass

Verification

Before fix:

$ echo \"hi\" | agent --model opencode/gemini-3-pro
...
undefined is not an object (evaluating 'Log.Default.lazy.info')

After fix:

$ echo \"hi\" | agent --model link-assistant/echo --no-always-accept-stdin
{
  \"type\": \"status\",
  ...
}
{
  \"type\": \"step_start\",
  ...
}

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