MODULE 04 · LESSON 4.3
Resolve competing changes and recover without destructive history edits.
Use the concept at the correct boundary
This topic earns its place in CourseFlow by changing something another person can inspect, test or review. This decision shapes the frontend boundary: what is rendered, what becomes interactive, and which state is allowed to cross into another component or route.
Here, that decision supports a specific checkpoint: Move the tracker through a feature branch, review and release tag. A reviewable result should include a focused component test, an accessibility check and a before/after browser trace rather than a claim that the feature simply works.
Merge Conflicts and Safe Recovery workflow
- 1Conflict Markers
- 2Rebase Versus Merge
- 3Revert
- 4Reflog
A practical model for merge conflicts and safe recovery
Resolve competing changes and recover without destructive history edits. The useful unit of understanding is the boundary: who owns the decision, which input crosses it, what result is visible and how a failure is reported.
- Conflict Markers: Implement one behavior that another learner can reproduce without reading your mind.
- Rebase Versus Merge: Compare the simplest correct approach with one credible alternative.
- Revert: State the assumption this concept relies on and show how the system behaves when it is false.
- Reflog: Connect this concept to the module checkpoint and identify the evidence a reviewer should expect.
What the example proves
Start by locating conflict markers in the sample. Then trace what reaches rebase versus merge and what the caller receives back.
git status
# edit conflicted files
git add src/app.js
git commitWrite down what the sample assumes about conflict markers. Break that assumption deliberately and inspect the response.
Implement and verify one behavior
- 1Conflict Markers
Compare expected and actual output before editing; the difference tells you where to investigate.
- 2Rebase Versus Merge
Keep names tied to the product rule so a reviewer can follow the change without decoding abbreviations.
- 3Revert
Add a regression check close to the boundary where this behavior can fail.
- 4Reflog
Describe the behavior in one sentence, then choose the smallest input that can prove it.
Common design traps
- Treating conflict markers as vocabulary instead of defining the behavior it must produce.
- Testing the expected path while ignoring an empty, invalid, repeated or unauthorized case around rebase versus merge.
- Allowing revert to cross a boundary without an explicit contract or useful error.
- Changing several layers before capturing the first piece of evidence, which makes the original cause harder to see.
Diagnose before changing code
- Reduce the problem to the smallest failing Merge Conflicts and Safe Recovery case.
- Capture the actual input and output at the conflict markers boundary.
- Read the first relevant error, request, trace or query rather than the loudest downstream symptom.
- Test one explanation for the failure in rebase versus merge; avoid changing two variables together.
- Keep a regression check that would expose the same defect if it returned.
Security decision
Assume data from props, storage, URLs and APIs can be malformed. Do not expose secrets in client bundles, and do not treat hidden UI as authorization.
Performance decision
Measure shipped JavaScript, rendering work and network waterfalls. Move work off the client only when the measured trade-off supports it.
PRACTICE
Build something you can inspect
Create a controlled conflict on two branches, resolve it, and document the chosen result.
Stretch challenge
Add observability for rebase versus merge without leaking personal data, secrets or noisy implementation details.
Definition of done
- The behavior around conflict markers works with realistic input.
- A failure involving rebase versus merge is handled clearly and without leaking sensitive detail.
- The implementation remains keyboard-usable when it produces an interface.
- Your evidence directly supports the claim made in the exercise.
- The README records the important trade-off without pretending the solution is universal.
Check your reasoning
When is git revert safer than rewriting published history?
Answer by naming the expected conflict markers behavior, the layer responsible for it and the evidence that would confirm your explanation.
Where would you investigate the first failure?
Start where rebase versus merge crosses a boundary. Compare the actual input and output there before following downstream symptoms.
What would make this work reviewable?
Show the focused change, repeatable steps, the result of your check and one honest trade-off connected to revert.
What to carry into the next lesson
- Resolve competing changes and recover without destructive history edits.
- Keep conflict markers visible at the boundary where it can be tested.
- Use evidence from rebase versus merge before widening the implementation.
References and related reading
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