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Use case: bug fixing

Fix Bugs Automatically, From Issue to Merged PR

Hand CodeCourier a bug report and get back a pull request that reproduces the bug, fixes it, and proves the fix with a passing test suite - all in an isolated sandbox, with you reviewing the diff instead of writing it.

Try CodeCourierHow Issue Sessions work

The boring-bug tax

Most bug reports are not hard. They are just expensive. Someone has to drop what they are doing, reproduce the issue, dig through unfamiliar code, write a fix, add a test, and open a PR. Multiply that by a backlog of small, well-scoped bugs and you have lost a senior engineer to context-switching and triage. The interesting work waits while the boring work eats the week. The tax is not the difficulty of any single bug - it is the constant interruption of clearing them.

How it works

How autonomous bug fixing works

Step 1

Reproduce the bug

CodeCourier reads the issue, spins up an isolated sandbox with your repo, and reproduces the failure first. If it cannot reproduce it, it says so and escalates rather than guessing at a fix.

Step 2

Write the fix

With the bug reproduced, the agent locates the root cause across files, writes the smallest correct fix, and follows your team's conventions through its persona instead of inventing its own style.

Step 3

Prove it with tests

It adds or updates a test that fails before the fix and passes after, then runs the full suite in the sandbox to confirm nothing else broke. Green is the bar, not a guess.

Step 4

Open a reviewable PR

CodeCourier opens a pull request with the diff, the reasoning, and the test evidence, ready for review - or for auto-merge if you have classed this kind of low-risk fix for it.

Why the sandbox matters

Every fix runs in a disposable, isolated sandbox with credentials scoped down and the blast radius contained. The agent can reproduce, edit, and run your full test suite without ever touching production or a developer's machine. If a fix is wrong, it fails inside the sandbox where it is harmless - not in your repo. Isolation is what makes autonomous bug fixing safe enough to trust with real code.

More on sandbox isolation

What it does well

  • Well-scoped, reproducible bugs from your tracker (GitHub, Jira, Linear)
  • Logic errors, off-by-one and edge-case failures, regressions caught by tests
  • Fixes that can be verified by a passing test in your existing suite
  • Backlogs of small, repetitive bugs that drain senior time

What it will not do

  • Vague reports it cannot reproduce - it escalates to a human instead of guessing
  • Open-ended product decisions or ambiguous requirements
  • Architecture-level rewrites masquerading as a bug fix
  • Anything outside your defined auto-merge class still waits for human review

Representative of how CodeCourier runs as of June 2026. Results depend on your codebase, test coverage, and the scope of the job. CodeCourier escalates to a human when it cannot reproduce or verify a change rather than guessing.

Proof

See it on a real bug

The honest test is your own backlog. Point CodeCourier at a real, reproducible bug and watch it open a tested PR - then judge the diff, not the demo.

Read the issue-to-PR walkthrough
FAQ
Can CodeCourier really fix bugs without an engineer?
For well-scoped, reproducible bugs, yes - it reproduces the failure, writes the fix, adds a test that proves it, and opens a PR, all in an isolated sandbox. The honest caveat is scope: vague or non-reproducible reports are escalated to a human rather than guessed at, and you stay in control of what merges. Most teams start in review-only mode and let the agent earn an auto-merge class for low-risk fixes over time.
How does it make sure the fix is correct?
It proves the fix with tests. CodeCourier adds or updates a test that fails before the change and passes after, then runs your full suite in the sandbox to confirm nothing else regressed. If it cannot make the suite pass, it does not open a green PR - it reports the blocker. The bar is a verifiable, passing test, not the agent's confidence.
Is it safe to let an AI agent change my code?
That is exactly why every run happens in a disposable, isolated sandbox with scoped credentials. The agent never touches production or a developer's machine; a bad fix fails harmlessly inside the sandbox. Nothing reaches your default branch except a reviewable pull request, and merge policy stays yours. See our sandbox isolation page for the security model.
Which issue trackers does it work with?
CodeCourier is issue-driven, so a tracked ticket maps to a run. It connects to GitHub Issues today, with Jira and Linear on the integrations roadmap. A bug report comes in, an isolated session reproduces and fixes it, and a pull request goes back out - the ticket is the unit of work and the audit trail.

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