Repair the mistake. Then do it without choices.
Open Transfer Path · Watch the 1:58 demonstration · Source and setup
A learner can reach the right answer through two wrong steps. They can also pick a correct multiple-choice option without writing the operation themselves. Counterstep turns those gaps into a repair-and-practice workflow for learners and tutors, on a small page that needs no account, cloud model or student-data upload.
The new Transfer Path keeps the original problem fixed, asks for a repaired solution, then moves to a typed next step and a changed-structure question. Its tutor note preserves the questions, every submitted response, feedback and requested help.
A correct answer cannot erase the broken working
The opening example ends at the correct x = 2, but its expansion and following step are wrong. The exact checker finds the first changed solution set. Repair the subsequent equations while the original problem stays locked. The complete revised chain must preserve that original solution and finish with x isolated.
A hint or exact test value is optional and explicitly requested. The tool does not automatically supply the repaired equation.
Write the operation, not just a final answer
The earlier Classic practice offered two next-step buttons. Transfer Path asks the learner to write an equation, without those choices.
When the task asks for expansion, entering the correct final value of x is not enough. The tool reports that it has the same solution set but is not the requested operation. A second check compares the resulting left/right affine coefficients, permits equation-side swaps, and checks the requested form. Expansion removes brackets; arithmetic produces a numeric literal. This is a constrained task check, not a general proof checker.
After that card, a different seed produces a changed layout, sign or inner expression. The demonstration moves from a familiar expansion to a bracket containing a coefficient on x and a subtraction, on the other side of the equation. It does not claim that two cards establish transfer to arbitrary algebra.
Help stays help, even after reopening
Correct on the first response, correct after feedback, and completed with a hint or worked step are separate outcomes. A revealed worked step stays marked assisted when it is entered correctly. Help on that earlier card does not automatically mark a different fresh card assisted.
Save an unfinished response, reopen it, and continue with the same question and draft. Replay reconstructs questions from the stored exercise seed and recomputes results from recorded actions. Saved verdicts are ignored. Stale exports are rejected rather than replacing newer work with an old result.
The readable tutor note includes each question, requested operation, submitted equation and help history. Untrusted response text is fenced in Markdown. The on-screen note matches the downloaded note. A personal practice file is not an authenticated grade; its holder can edit it or construct another valid history.
A small learned model with a specific job
The existing 1,637-parameter neural ranker, trained on 3,200 original generated error pairs, suggests one of five practice families: distribution, balancing, division, bracket negatives and arithmetic. Transfer Path uses its actual inference result. If the model abstains, the learner must choose rather than being silently assigned the top label. Manual overrides remain available.
The model does not decide mathematical correctness. That remains the separate exact BigInt rational checker. The original model weights, exact engine and Classic application are byte-identical to the earlier release; no retraining or new classification accuracy is claimed.
The original fresh numeric evaluation was reproduced: 487 of 600 top-class matches, with 475 suggestions issued and 125 withheld. This remains evaluation within the five original authored generators. It does not validate a learner diagnosis, the new question structures or educational effectiveness. Earlier model failures and evaluation scope remain in the source.
What was executed
The release passed 85 Node tests, all 250 original Fraction-reference cases, and an independent Python AST/Fraction check of 150 generated tasks and 750 submitted-response cases. Those cases check valid equivalents, side swaps, changed solutions, copied questions and solution-equivalent but unrequested operations.
All 45 browser workflows passed locally and again on the anonymous public deployment: 16 Classic plus 29 Transfer Path workflows. They exercise actual learned inference, typed responses, help accounting, unfinished drafts, replay, downloads, hostile inputs, mobile layout and computation after disconnection. No inference or answer results are mocked.
The public application retains its security policy. Only the observed index/path/judge anchor rewrites were allowed, with their destinations and identical embedded scripts checked. Its source files, model, package and video were checked against the release hashes. The 118-second demonstration fully decodes with non-silent audio and records actual application actions using synthetic equations and disclosed stock synthetic narration.
Executed release · Anonymous verification · Download source and tests
These are internal software checks, not a teacher endorsement, learner trial or measured learning improvement. The next validation is an authorized tutor review and usability task: can a learner repair, write, resume and explain the recorded work without interface coaching?
Scope and authorship
Transfer Path supports 2–12 linear equations in x with constants, fractions and parentheses, and requires one solution for its repair exercise. Nonlinear products, variable denominators, inequalities and other variables remain outside scope. Supported equivalent equations do not validate unwritten explanations or establish understanding. Practice is bounded to five authored families and 60 recorded actions per path.
The self-contained page includes the code and model. It computes without additional network access while open; direct local-file navigation was not validated in this environment. No identity, sign-in, teacher account or remote model is required. Exported files contain the equations and responses the user chooses to share.
Original Counterstep work was created September 7, 2026. Transfer Path was added September 8, during the hackathon window, with substantial AI assistance. Original code is MIT licensed. Narration uses the disclosed stock Kokoro af_heart synthetic voice, not a cloned person's voice. No third-party music, learner footage, paying users or prize is claimed.
This improves the existing Prom Fall Classic entry. The separate Amazon Counterstep Relay submission, earlier immutable releases and unrelated portfolio production remain unchanged.
The downloadable archive preserves the tested application release. The source branch additionally retains the later public-verification helper, its initial failed HTML-rewrite check, the corrected browser-runner URL convention, the diagnosed hosting differences and the final verification result.
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