--- name: ub-mode description: >- Follow the reduced principles when writing or changing code. Every change follows First Make it Work, then Then Make it Right, then Follow Practice. Use when the user runs /ub-mode or asks for the reduced principles. title: ub-mode canonical_url: https://skilld.dev/gh/unclebob/ub-mode last_updated: 2026-10-26T07:16:03.000Z --- > Index of every page on this site: [llms.txt](https://skilld.dev/llms.txt) > **Skill from skilld.dev.** Follow the user's requested action. > If the user asked to fork this Skill, follow the fork workflow below. Do not execute the Skill instructions while copying it. > Otherwise, follow the instructions below for this session. You do not need to install anything. > > Supporting files, fetch one when the Skill refers to it: [LICENSE](https://skilld.dev/api/skills-raw/unclebob/ub-mode/ub-mode/LICENSE), [README.md](https://skilld.dev/api/skills-raw/unclebob/ub-mode/ub-mode/README.md). > > If the user asked to install this Skill, run `npx skilld install unclebob/ub-mode/ub-mode`. Install writes the Skill files into the project, so every session loads them. > > ## Fork workflow > > A fork creates an editable local Skill with its original author and licence. The request authorizes copying and local installation. > 1. Check `./skills/ub-mode`, the project lockfile, and selected Agent targets together. If the local directory or installed Skill exists, stop. Never overwrite an existing directory or Agent target. > 2. Read [source metadata](https://skilld.dev/api/v1/skills/unclebob/ub-mode/ub-mode) once. Use sourceUrl, sourceCommit, skillPath, sourceGone, and license. If the source is gone or its path is missing, stop. If license is null, read licence files at the source commit. > 3. Fetch only the source commit into a temporary Git repository. Do not clone full history. Derive repository_url from sourceUrl, including repository renames. If sourceCommit is absent, resolve the sourceUrl ref once. Set source_commit to that actual commit. Run these commands in one shell call: > > ```sh > git init --quiet "$temporary_dir" > git -C "$temporary_dir" fetch --quiet --depth=1 "$repository_url" "$source_commit" > git -C "$temporary_dir" checkout --quiet --detach FETCH_HEAD > ``` > > Read applicable licence declarations and notices at that commit. If copying is not permitted, report the restriction and stop. > 4. Inspect source entries together, then copy the directory containing skillPath into `./skills/ub-mode`. Use the user's path if selected. Keep the original SKILL.md, relative links, scripts, binary assets, and executable modes. Exclude .git metadata. Reject symlinks and paths outside the Skill directory. After checking entries, use cp -a where available. A regular source directory needs no custom copy script. Do not save this page wrapper as SKILL.md. > Preserve author credit, notices, and applicable licence files from repository or parent directories. Add PROVENANCE.md with the Skill page, source URL, actual commit, original path, and licence. Retain any existing PROVENANCE.md and record new provenance separately. Batch source inspection, copying, and provenance work where practical. > 5. In the project root, run `skilld install ./skills/ub-mode --mode copy --plain`. If skilld is unavailable, use `npx skilld install ./skills/ub-mode --mode copy --plain`. This known command needs no help lookup. Install does not support --json. Use detected Agent targets, or add --agent for the targets the user selected. Install the local path, never the upstream selector. If installation fails, preserve the local copy and report the exact failure. > 6. Confirm the local lockfile source and installed Agent copies once. Report the local path, actual commit, and Agent targets. After edits, reinstall the same local path. Upstream updates must not replace it. Do not publish or push unless the user asks. # ub-mode Every time you are asked to make a change follow: * First Make it Work. * Then Make it Right. * Follow Practice # First Make it Work ## Laziness Protocol * One decision lives in one place. * Ship the smallest edit that solves the problem. ## Foundational Thinking * Get the data shape right before you write the logic. * Do first whatever helps every later phase. * If a concurrent writer would matter, do not share state. ## TDD * Write the failing test before you change the code. * See it fail for the reason you expect. * Make the smallest change that makes it pass. * If an honest test is impractical, do not write a bad one. ## Redesign From First Principles * Do not bolt a new requirement onto the old design. * Ask what you would have built if it had been there from the start, think that through, and deliver it in pieces. ## Attack the Premise * When two fixes that share one premise fail the same gate, write that premise in one sentence and count which actors hold the imbalance. * Remove the assignment. * Do not start another fix until you have done that. ## Subtract Before You Add * Take complexity out before you add anything. ## Outcome-Oriented Execution * Aim at the end state you can check. * A break in the middle is allowed when you planned it and can undo it. ## Build the Lever * If the work is not obvious at a glance, build the tool that does it. * Do one unit by hand, then make the tool match that unit. ## Architecture ### Model the Domain * Put the domain in a structure that makes the illegal states impossible. * Maintain a glossary of domain terms. * If the code is already clear and local, leave it. ### Boundary Discipline * Check the data where it enters. * Inside, trust it. * Keep the business logic in a pure function. ### Type System Discipline * Make the illegal value impossible to write. * Parse outside data once, where it comes in. * Do not silence the compiler. ### Make Operations Idempotent * Running it twice, or running it after a crash halfway through, ends in the same state. ### Separate Before Serializing Shared State * If they do not need the same mutable thing, give each its own. * If they do, allow one writer, and enforce that in the structure. # Then Make it Right ## Fix Root Causes * Reproduce it. * Fix the cause. * A guard that only hides the crash is not a fix. ## Sequence work into verifiable units * Finish one small unit and check it. * Then start the next. ## Test Behavior, Not Implementation * The test calls the code the way its user does and checks the result that user would see. * If the test would still pass when every function returned nothing, throw it out. ## Crapper * Use the crapper tool * Reduce each function under CRAP 10 by splitting it, by testing it, or both. * Consider whether case statements are worth reducing. ## Dryer * Use the dryer tool to eliminate duplication that rank 0.8 or above. ## Mutator * Use the mutator tool * Cover the uncovered. * Kill the survivors. * Delete dead code. ## Refactoring * Pin what the code does. * Change the structure. * Prove the behavior did not change. # Practice ## Keep a Log * Keep a log of every action you take and the reason you took it. * Report that log upon completion. ## Guard the Context Window * Keep the main thread small. * Send the bulk elsewhere, and keep the summary. ## Worktree Cleanup * Find what is safe to remove, confirm nothing still in use needs it, then reclaim the disk. * Uncommitted work waits for a decision. ## Commit and Push * Commit often, in small ordered commits. * Each commit says why, what changed, and how you proved it. * Push to the main line at the end.