Openspec Apply Change Agent Skill

Implement tasks from an OpenSpec change.

Input: Optionally specify a change name. If omitted, check if it can be inferred from conversation context. If vague or ambiguous you MUST prompt for available changes.

Steps

• Select the change

If a name is provided, use it. Otherwise:

• Infer from conversation context if the user mentioned a change
• Auto-select if only one active change exists
• If ambiguous, run openspec list --json to get available changes and use the AskUserQuestion tool to let the user select

Always announce: "Using change: <name>" and how to override (e.g., /opsx:apply <other>).

• Check status to understand the schema

   openspec status --change "<name>" --json

Parse the JSON to understand:

• schemaName: The workflow being used (e.g., "spec-driven")
• Which artifact contains the tasks (typically "tasks" for spec-driven, check status for others)

• Get apply instructions

   openspec instructions apply --change "<name>" --json

This returns:

• Context file paths (varies by schema - could be proposal/specs/design/tasks or spec/tests/implementation/docs)
• Progress (total, complete, remaining)
• Task list with status
• Dynamic instruction based on current state

Handle states:

• If state: "blocked" (missing artifacts): show message, suggest using openspec-continue-change
• If state: "all_done": congratulate, suggest archive
• Otherwise: proceed to implementation

• Read context files

Read the files listed in contextFiles from the apply instructions output.

The files depend on the schema being used:

• spec-driven: proposal, specs, design, tasks
• Other schemas: follow the contextFiles from CLI output

• Show current progress

Display:

• Schema being used
• Progress: "N/M tasks complete"
• Remaining tasks overview
• Dynamic instruction from CLI

• Implement tasks (loop until done or blocked)

For each pending task:

• Show which task is being worked on
• Make the code changes required
• Keep changes minimal and focused
• Mark task complete in the tasks file: - [ ] → - [x]
• Continue to next task

Pause if:

• Task is unclear → ask for clarification
• Implementation reveals a design issue → suggest updating artifacts
• Error or blocker encountered → report and wait for guidance
• User interrupts

• On completion or pause, show status

Display:

• Tasks completed this session
• Overall progress: "N/M tasks complete"
• If all done: suggest archive
• If paused: explain why and wait for guidance

Output During Implementation

## Implementing: <change-name> (schema: <schema-name>)

Working on task 3/7: <task description>
[...implementation happening...]
✓ Task complete

Working on task 4/7: <task description>
[...implementation happening...]
✓ Task complete

Output On Completion

## Implementation Complete

**Change:** <change-name>
**Schema:** <schema-name>
**Progress:** 7/7 tasks complete ✓

### Completed This Session
- [x] Task 1
- [x] Task 2
...

All tasks complete! Ready to archive this change.

Output On Pause (Issue Encountered)

## Implementation Paused

**Change:** <change-name>
**Schema:** <schema-name>
**Progress:** 4/7 tasks complete

### Issue Encountered
<description of the issue>

**Options:**
1. <option 1>
2. <option 2>
3. Other approach

What would you like to do?

Guardrails

• Keep going through tasks until done or blocked
• Always read context files before starting (from the apply instructions output)
• If task is ambiguous, pause and ask before implementing
• If implementation reveals issues, pause and suggest artifact updates
• Keep code changes minimal and scoped to each task
• Update task checkbox immediately after completing each task
• Pause on errors, blockers, or unclear requirements - don't guess
• Use contextFiles from CLI output, don't assume specific file names

Fluid Workflow Integration

This skill supports the "actions on a change" model:

• Can be invoked anytime: Before all artifacts are done (if tasks exist), after partial implementation, interleaved with other actions
• Allows artifact updates: If implementation reveals design issues, suggest updating artifacts - not phase-locked, work fluidly