rollback - safely reverse a completed feature

Context reuse: Reuse any required file already loaded in project instructions or the current session. Read it again only if absent, changed, or exact current bytes or line references are needed.

First action: Before project inspection, preflight, or any other tool call, publish running to blueprint/.state/run.json using the dashboard activity contract in AGENTS.md.

Where this sits in the workflow:

completed feature + git history  ->  [rollback]  ->  /implement  ->  /check  ->  /complete
(archive + squashed commit)           (risk review     (reverse       (prove)     (log + merge)
                                       + spec)          product diff)

This skill plans a rollback. It does not change product code, create a branch, commit, merge, or push. It identifies the completed feature and its exact git commit, checks what changed afterward, writes a guarded rollback spec, then stops for review. /implement performs the reversal only after the user approves that spec.

Input

A completed feature by build-plan number, name, or archive path, plus an optional reason. Examples:

/rollback 4 because the new export flow is corrupting files
/rollback "PDF export"
/rollback blueprint/history/features/04-pdf-export.md

With no target, list a short set of recent completed feature archives and ask the user to choose. Never silently pick the latest feature. If the reason is missing, ask for one before writing the spec because the rollback archive must explain why the feature was removed.

Step 0 - preflight

Read AGENTS.md, blueprint/build-plan.md, blueprint/context/current-feature.md, the completed feature archives, and git state.

Stop before writing when:

• the directory is not a git repository
• current-feature.md already holds active work
• the working tree is dirty, including unrelated untracked work
• the current branch is not the local main or default branch
• the target is not a checked build-plan feature with a matching archive
• the archive or its introducing commit cannot be identified unambiguously

Do not stash, discard, fetch, pull, switch branches, or clean the tree from this skill.

Step 1 - resolve the exact feature

Match the requested number or name against both the checked build-plan items and blueprint/history/features/*.md. Exclude the directory README.

Use the archive path to locate the commit that added it:

git log --diff-filter=A --format="%H %s" HEAD -- <archive-path>

Use the newest matching commit reachable from the current branch. Confirm the archive was added by that commit and its subject and diff are consistent with the requested feature. If the target is a merge commit, stop before Step 2 and before writing or changing blueprint/context/current-feature.md. Do not record a target parent or choose a mainline. Publish blocked to blueprint/.state/run.json, explain that Blueprint cannot safely infer which merge parent represents the pre-feature state, and include the exact /rollback command the user can rerun after choosing a safe remediation or mainline strategy. /implement retains its merge-target stop as defense in depth. If the archive was never committed, explain that git cannot reconstruct a safe rollback from it.

Step 2 - separate product changes from Blueprint history

Inspect the target commit and build the product-path set from the files it changed. Exclude these protected workflow paths:

• .agents/**
• .claude/**
• blueprint/**
• AGENTS.md
• CLAUDE.md
• prototypes/**

The rollback must preserve the original feature archive, later planning changes, the active rollback spec, adapter skills, and throwaway prototype history. Root README.md and ordinary app docs are product files unless the project says otherwise.

If no product paths remain, stop. Do not create an empty rollback that only rewrites Blueprint records.

Step 3 - review later-change risk

Inspect every commit after the target through HEAD that touches one of the product paths. Also read later completed feature specs when they mention the target, its contracts, routes, data, or files.

Classify the result:

• No overlap - no later commit touched the target product paths.
• Overlap, likely compatible - later edits touched the same paths, but the target change can be reversed without removing their behavior.
• Dependency risk - later work appears to require the target's API, schema, route, component, or data.
• Blocked - safe behavior after reversal is unclear, data migration would be destructive, or a cascading rollback would be required.

Path overlap is a warning signal, not proof of dependency. Explain the concrete later commit and contract involved. Never silently cascade into reverting other features. For a blocked case, stop and ask the user to choose a narrower remediation or explicitly plan the dependent rollbacks.

Step 4 - write the rollback spec

Write blueprint/context/current-feature.md using reference/rollback-spec-template.md. Fill in:

• the full rollback branch from the configured prefix plus the rollback title in lowercase kebab-case
• target feature and archive
• target commit and parent commit as full 40-character SHA values
• user's reason
• product paths introduced or changed by the target
• protected workflow paths
• later commits reviewed and the risk classification
• compatibility work that is allowed, if any
• exact verification commands and observable removal criteria

The first build step must apply the target commit's product diff in reverse using the guarded Type: Rollback behavior in /implement. Later steps may repair only the specific downstream compatibility issues named in the spec. Do not use a rollback as permission for unrelated cleanup.

Older installations may not have blueprint/history/rollbacks/ yet because updates preserve user history. That is not a planning blocker; /complete creates the directory when it archives the approved rollback.

Red-team the draft before presenting it:

• does it preserve all Blueprint history and later plan changes?
• could it remove data or require a destructive migration?
• does later code import or call something the target introduced?
• are the removal criteria observable rather than phrased as "feature gone"?
• can each compatibility edit be reviewed separately?

Tighten the spec, then stop. Summarize the target commit, affected product paths, later-change risk, and what the critique changed. Tell the user to review the spec, then run /implement to create the rollback branch and apply it.

Rules

• Preserve history. Never delete or rewrite the original feature archive.
• Plan only. This skill writes the rollback spec and nothing else.
• One completed feature per rollback.
• Record both the target commit and its parent as full 40-character SHA values. Each value must resolve to the recorded commit in the current repository.
• Never use git reset --hard, force-push, history rewriting, or broad file restoration.
• Never infer permission to cascade into later features or destroy stored data.
• A rollback still uses /implement, /check, and /complete review gates.

Formatting

Format the output to match blueprint/context/ai-interaction.md: concise, scannable markdown with a small risk table when later commits overlap.