speckit-modify

name	speckit-modify
description	Modify an existing feature with impact analysis and backward compatibility tracking.
compatibility	Requires spec-kit project structure with .specify/ directory
metadata	{"author":"github-spec-kit","source":"workflows:commands/modify.md"}

The user input to you can be provided directly by the agent or as a command argument - you MUST consider it before proceeding with the prompt (if not empty).

User input:

$ARGUMENTS

The text the user typed after /speckit.workflows.modify (or /speckit.modify) in the triggering message can be:

• /speckit.workflows.modify <feature-number> "modification description" - Direct with feature number
• /speckit.workflows.modify "modification description" - Interactive (will prompt for feature selection)

Assume you always have it available in this conversation even if $ARGUMENTS appears literally below.

Given that modification request, do this:

1. Parse $ARGUMENTS to check if feature number is provided

   • If starts with 3 digits (e.g., "014 add compression"), extract feature number and description
   • If no leading digits (e.g., "add compression"), treat as description-only (interactive mode)

2. If interactive mode (no feature number provided): a. Run .specify/extensions/workflows/scripts/bash/create-modification.sh --list-features "<description>" to get list of features b. Parse the JSON output which contains: {"mode":"list","description":"...","features":[...]} c. Present the features list to the user in a clear, numbered format:

   Which feature do you want to modify?
   
   1. 001 - ability-for-new
   2. 002 - ability-for-users
   3. 014 - edit-profile-form
   ...
   
   Type the feature number (e.g., 014) or respond with the line number (e.g., 3).
   

   d. Wait for user response with their selection e. Extract the feature number from their response (handle both "014" and "3" formats) f. Continue to step 3 with the selected feature number

3. Normal workflow (feature number now available): Run the script .specify/extensions/workflows/scripts/bash/create-modification.sh --json <feature-number> "<description>" from repo root and parse its JSON output for MOD_ID, BRANCH_NAME, MOD_SPEC_FILE, IMPACT_FILE, and FEATURE_NAME. All file paths must be absolute. IMPORTANT You must only ever run this script once per feature selection. The JSON is provided in the terminal as output - always refer to it to get the actual content you're looking for.

4. Read the impact analysis from IMPACT_FILE to understand what files and contracts are affected.

5. Load the original feature spec from specs/<FEATURE_NAME>/spec.md to understand the baseline.

6. Load .specify/extensions/workflows/templates/modify/modification-template.md to understand required sections.

7. Write the modification spec to MOD_SPEC_FILE using the template structure:

   • Fill "Why Modify?" with business justification from description
   • Fill "What's Changing?" sections (Added/Modified/Removed) based on description
   • Include impact analysis summary from IMPACT_FILE
   • Document backward compatibility considerations
   • Leave detailed implementation sections for planning phase

8. Report completion with Next Steps:

Modification workflow initialized

**Modification ID**: [MOD_ID]
**Original Feature**: specs/[FEATURE_NAME]
**Modification Spec**: [MOD_SPEC_FILE]
**Impact Analysis**: [IMPACT_FILE]

**Impact Summary:**
- [X] files affected
- [Y] contracts changed
- [Z] tests need updates

**Next Steps:**
1. Review modification spec and impact analysis
2. Refine requirements if needed (edit modification-spec.md)
3. Run `/speckit.plan` to create implementation plan
4. Run `/speckit.tasks` to break down into tasks
5. Run `/speckit.implement` to execute changes

**Reminder**: Consider backward compatibility and migration strategy

Note: The script creates and checks out the new branch, runs impact analysis, and prepares directory structure before writing.

Interactive Mode Usage Examples:

• User: /speckit.workflows.modify "add avatar compression" -> Shows feature list -> User selects -> Creates modification
• User: /speckit.workflows.modify 014 "add avatar compression" -> Directly creates modification for feature 014