CodeShift

Most tools give developers migration guides, dependency warnings, or a list of files to change. CodeShift answers a harder question: what will actually happen to the application if we perform the upgrade? Software migrations become expensive because developers must discover the current stack, understand breaking changes, resolve dependency conflicts, update code, run builds and tests, diagnose regressions, and decide whether failures were already present or were caused by the migration. That investigation can take days or weeks before a production repository can be changed with confidence. CodeShift turns this into an executable migration rehearsal. A developer provides a public GitHub repository or ZIP. CodeShift automatically analyzes the repository and detects its ecosystem, framework, current version, runtime, package manager, lockfile, dependencies, scripts, source structure, and configuration. It then uses a versioned migration knowledge registry to present valid upgrade targets, so the developer can simply select the desired destination instead of manually identifying the framework and source version. After target selection, IBM watsonx.ai analyzes the migration using the repository profile, curated migration knowledge, relevant source context, and detected risks. The result is a structured migration plan and set of auditable findings. The defining feature is CodeShift's disposable executable Twin. Before making any changes, CodeShift establishes a baseline by running the repository's applicable install, build, test, and lint workflow. It then creates an isolated Twin and rehearses the selected migration there. The original repository remains untouched. CodeShift compares the migrated Twin against the baseline to identify regressions and migration-caused failures. It clusters failure evidence, uses watsonx.ai to diagnose relevant issues, and can apply targeted repairs inside the Twin before running verification again. Every step is evidence-backed: findings map to actions, changed files, diffs, diagnoses, repairs, and verification results. The final output is more than a migration checklist. Developers can see what the repository contains, what the upgrade changes, what actually failed, why it failed, what was repaired, and what still requires human review. CodeShift then generates an AgentTaskSpec and downloadable 8-artifacts Agent Pack containing the implementation plan, findings, affected files, constraints, verification evidence, patch diff, acceptance criteria, and an implementation prompt ready for a coding agent. Built for developers and engineering teams maintaining evolving codebases, CodeShift turns migration investigation into a repeatable, evidence-backed rehearsal measured in minutes for all supported migrations. Don't discover migration failures after changing the real repository. Rehearse the upgrade first.