kramme-code-rewrite-clean

name	kramme:code:rewrite-clean
description	Scrap a working-but-mediocre fix and reimplement elegantly. Use after making a fix that works but feels hacky. Applies Chesterton's Fence before scrapping, emits SIMPLICITY CHECK at design time, and rejects rewrites that require modifying tests to pass.
disable-model-invocation	true
user-invocable	true

Rewrite Clean

Knowing everything you know now, scrap this and implement the elegant solution.

Step 0: Validate Context

Before proceeding, review the current conversation to confirm:

1. Implementation work exists — We've written or modified code in this session.
2. The work is complete enough — The fix/feature works (even if inelegantly).
3. There's something to improve — The implementation has identifiable inelegance.

If any of these are missing, STOP and explain:

• No implementation work? → "There's no implementation in this conversation to refactor. This command is for redoing existing work more elegantly."
• Work isn't complete? → "Let's finish the current implementation first, then we can evaluate whether it needs an elegant refactor."
• Nothing obviously inelegant? → "The current implementation looks reasonable. What specifically feels hacky or inelegant to you?"

Only proceed if all three conditions are met.

Prerequisites — When NOT to rewrite

Even when Step 0 passes, do not proceed if any of these apply:

• The solution is fine, just unfamiliar. Unfamiliarity is not inelegance. Read the code a second time before deciding to scrap it.
• You don't understand the problem yet. Rewriting code you don't fully understand deletes subtle behavior. If you cannot explain what edge cases the mediocre version handles, stop.
• Time pressure makes "good enough" acceptable. A working fix before a deadline is not a candidate for a scrap-and-rewrite. Ship it; log a follow-up if the inelegance matters.
• The inelegance is inherent to the problem domain. Some problems are ugly. If the ugliness tracks the domain rather than the implementation, a rewrite will reproduce it in a different shape.
• It's performance-critical and the current shape is measured-fast. "Elegant" does not override measured performance. Check benchmarks before rewriting hot paths.

The Core Insight

First implementations often solve the problem but in a hacky way. Having solved the problem once, you now understand it deeply enough to implement it properly from scratch.

Do not preserve the mediocre code. The whole point is to start fresh.

Process

1. Extract What You Learned

Before touching any code, apply Chesterton's Fence to the mediocre version. You wrote it; that does not mean you remember every decision inside it. Verify you understand why each non-trivial piece exists:

1. Responsibility — What does each part do, including side effects?
2. Callers — Who depends on the current shape? (Other modules? Tests? External consumers?)
3. Edge cases — What hidden inputs does it handle that the happy path obscures?
4. Tests — What behaviors do the tests lock in? Read them.
5. Git blame / session history — Why did each piece get added? Was any part added in response to a bug you hit during this session?

If you cannot answer all five for a given piece, you haven't earned the right to scrap it. Read more first.

Then articulate:

• What was the actual problem? (Not what you thought it was initially.)
• What constraints did you discover?
• What edge cases matter?
• What dependencies or interactions exist?

2. Identify the Inelegance

Be specific about what's wrong with the current solution:

• Unnecessary complexity?
• Wrong abstraction level?
• Coupling that shouldn't exist?
• Duplicated logic?
• Hard to understand or maintain?

3. Design the Elegant Solution

Think before coding. Emit a SIMPLICITY CHECK marker stating the minimum shape of the elegant solution:

SIMPLICITY CHECK: <one-line summary of the simplest elegant form that handles all discovered cases>

Then answer:

• What's the simplest approach that handles all the cases Chesterton's Fence surfaced?
• What abstraction, if any, makes this clearer? (Default: none. Abstractions are earned.)
• How would you explain this solution to someone else?

If the design expands beyond the SIMPLICITY CHECK, write a second line explaining what forced the expansion. If there is no forcing requirement, stay at the simpler form.

4. Scrap and Reimplement

1. Create a recovery point — Before reverting, preserve the mediocre fix so you can return to it if the rewrite turns out worse. Commit it on a throwaway branch (git switch -c rewrite-baseline && git commit -am "baseline: pre-rewrite") or stash with a labeled message (git stash push -u -m "pre-rewrite baseline"). State the exact recovery command before continuing.
2. Save the expected behavior — Note the files touched and the behavior to verify against, including the edge cases surfaced by Chesterton's Fence. This is the spec the rewrite must satisfy.
3. Revert the changes — Return the working tree to the state before the mediocre fix.
4. Implement the elegant solution — Write it fresh, properly.
5. Verify equivalence — Delegate to kramme:verify:run for the project's verification battery. If a test fails, the rewrite changed behavior — restore the recovery point or reclassify as a behavior change.

"Existing tests" in this skill includes any tests written or modified during the current session. The rewrite must satisfy them unchanged.

Common Rationalizations

These are the lies you will tell yourself to justify scrapping code that should stand. Each has a correct response:

• "The elegant version should be shorter." → Line count is not a goal. Clarity is. An elegant version can be longer if it reads top-to-bottom.
• "I remember writing this; I don't need to re-read it." → You remember the happy path. Chesterton's Fence is for the parts you don't remember writing for a reason.
• "The test is flaky; I'll just tweak it when the rewrite lands." → If the rewrite requires modifying a test, it changed behavior. Revert or reclassify.
• "The rewrite surfaced a bug in the original — I'll fix it in the rewrite." → No. A bug fix is its own slice. Revert, land the bug fix separately, then attempt the rewrite from the fixed baseline.
• "This abstraction is elegant in the abstract; the project just doesn't use it yet." → Not elegant — speculative. Wait for the third use case before introducing an abstraction the codebase does not yet need.
• "I'll rewrite and rename at the same time for consistency." → Two changes. Rename is its own slice, often its own PR. Pick one.

Red Flags

Rejection criteria. If any of these are true, revert the rewrite:

• The rewrite requires modifying tests to pass. Tests encode behavior. If the rewrite changes test expectations, it is a behavior change, not an elegant refactor. Revert or reclassify.
• The rewrite is longer without a stated clarity gain. Longer code is acceptable only when it reads more clearly top-to-bottom. If "elegant" turned out longer and you cannot articulate the clarity gain, the original was probably fine. Discard the rewrite.
• Rewriting for personal preference, not codebase consistency. If the old shape matched the codebase and the new shape matches your taste, the old shape wins.
• Removing defensive checks without proving they're unreachable. If you cannot prove a check is dead (via types, invariants, or caller analysis), keep it. The mediocre version may have encoded a lesson.

Verification

Before declaring the rewrite done, self-check:

• All five Chesterton's Fence criteria were answered for every non-trivial piece of the original before scrapping.
• A SIMPLICITY CHECK marker was emitted at design time; any expansion beyond it has a documented forcing requirement.
• All existing tests pass without any test modifications.
• Build, typecheck, and lint all pass.
• The rewrite's behavior matches the saved-state notes, including edge cases.
• No bug found during the rewrite was silently folded in — any bug fix is a separate slice.
• The rewrite is shorter or equally clear. If it is longer and less clear, revert.

If any box is unchecked, finish the gap or revert before declaring done.