Jake Goldsborough

Lok Part 4: The Self-Healing Loop

Jan 28, 2026

3 min read

#ai

#tools

#rust

#dev

Last time I showed lok finding 25 bugs in itself and creating GitHub issues automatically. Today it fixed one of those bugs, submitted a PR, and then found a real bug in Discourse that I just pushed upstream.

Agentic Workflows

The missing piece was letting lok actually do things, not just talk about them. I added a few fields to the workflow TOML:

[[steps]]
name = "fix"
backend = "claude"
apply_edits = true
verify = "cargo build"
prompt = """
Fix this issue. Output JSON:
{"edits": [{"file": "src/main.rs", "old": "...", "new": "..."}], "summary": "..."}
"""

[[steps]]
name = "commit"
shell = "git add -A && git commit -m '{{ steps.fix.summary }}'"
depends_on = ["fix"]

Three new things:

  1. shell runs a command instead of querying an LLM
  2. apply_edits parses JSON from the LLM and patches files
  3. verify runs after edits to make sure they work

The {{ steps.fix.summary }} bit extracts a field from the JSON output. You can also do {{ arg.1 }} for positional arguments, so lok run fix-issue 42 passes 42 into the workflow.

Lok Fixes Itself

Issue #25 was about a redundant Clone implementation. The Delegator struct already derives Clone, but there was a manual impl at the bottom of the file doing the same thing.

I ran the fix workflow:

lok run fix-issue 25

It analyzed the issue, generated an edit to delete the redundant impl, applied it, ran cargo build to verify, committed with a message based on the fix summary, pushed the branch, and opened a PR.

The whole loop took maybe 30 seconds. I reviewed the diff, looked reasonable, merged it.

Finding Bugs in Discourse

Feeling confident, I pointed lok at the main Discourse codebase:

lok hunt ~/discourse/discourse

Both Codex and Claude found issues. Most were minor (confusing patterns, style things) but two stood out:

  1. A chat job with a TODO saying "delete after 2025-01-01" that was still there in January 2026. Pure dead code.

  2. A bug in the thread serializer. It had this pattern:

@opts[:include_thread_original_message].presence || true

The problem is .presence on false returns nil. So if you explicitly pass include_thread_original_message: false, it gets converted to nil, then || true kicks in, and your option is ignored.

One controller was passing false and getting true back. Nobody noticed because the behavior difference is subtle, but it was definitely wrong.

I created two PRs: #37333 #37334

The Vision

The pieces are coming together for a fully autonomous loop:

  1. lok hunt --issues finds bugs and creates GitHub issues
  2. lok run fix-issue 42 analyzes, fixes, verifies, commits, opens PR
  3. lok run review-pr 43 has multiple backends review the diff
  4. If they agree, merge

Humans become exception handlers. You get pinged when the LLMs disagree or flag something they are not confident about. Otherwise the codebase quietly improves itself.

We are not there yet. The fix workflow needs better error recovery, the review workflow needs the debate mode integrated, and I want confidence scores on the merge decision. But the foundation is solid.

What's Next

Honestly, I'm not 100% sure. I plan to just keep using it and adding/fixing things that I want or need. Stay tuned to see how the project evolves.

Next stop: unknown. But the tracks are laid.

Previous: Part 3: Dogfooding and Code Review

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