---
name: openspec-apply-change
description: Implement the tasks from a change. Use when the user wants to start implementing, continue implementation, or work through the tasks of an existing change.
license: MIT
compatibility: Claude Code — no external CLI required.
metadata:
  author: openspec (adapted for Claude Code)
  version: "1.0-claude"
  source: SAP-samples/cap-agentic-engineered
---

Implement the tasks from a change.

> **Adapted for Claude Code.** No `openspec` CLI. A change is a folder under
> `openspec/changes/<name>/`; tasks live in `tasks.md` as a Markdown checklist. Read the
> artifacts directly, implement, and flip `- [ ]` → `- [x]` with the Edit tool.

**Input**: Optionally specify a change name. If omitted, infer from conversation context; if ambiguous, prompt.

**Steps**

1. **Select the change**

   If a name is provided, use it. Otherwise list active changes:

   ```bash
   ls -1 openspec/changes 2>/dev/null | grep -v '^archive$'
   ```

   - Infer from conversation context if the user mentioned a change
   - Auto-select if only one active change exists
   - If ambiguous, use the **AskUserQuestion tool** to let the user choose

   Always announce: "Using change: <name>".

2. **Read the change artifacts**

   Read every artifact that exists in `openspec/changes/<name>/`:
   - `proposal.md` (what & why)
   - `design.md` (how)
   - `tasks.md` (the checklist you will execute)

   If `tasks.md` is missing, the change is not ready to implement — suggest the
   `openspec-propose` skill (or creating `tasks.md`) and stop.

3. **Assess progress**

   Count tasks in `tasks.md`:
   - Incomplete = lines matching `- [ ]`
   - Complete = lines matching `- [x]`

   Display: change name, "N/M tasks complete", and a short overview of what remains.
   If all tasks are already complete, congratulate and suggest archiving
   (the `openspec-archive-change` skill).

4. **Implement tasks (loop until done or blocked)**

   Mirror `tasks.md` into your task-tracking tool (`TaskCreate` / `TaskUpdate`) so progress
   is visible. For each pending task:
   - Show which task is being worked on
   - Make the code changes required — keep them minimal and focused on that task
   - **For SAP code, consult the relevant MCP server first** (`sap-cap`, `sap-fiori`,
     `sap-ui5` skills) — never guess CDS/Fiori/UI5 behavior
   - For non-trivial implementation, dispatch to the appropriate specialist sub-agent via
     the **Agent tool** rather than writing large code blocks inline
   - Mark the task complete by editing `tasks.md`: `- [ ]` → `- [x]`
   - Continue to the next task

   **Pause if:**
   - A task is unclear → ask for clarification
   - Implementation reveals a design issue → suggest updating `design.md`/`proposal.md`
   - An error or blocker is encountered → report and wait for guidance
   - The user interrupts

5. **On completion or pause, show status**

   - Tasks completed this session
   - Overall progress: "N/M tasks complete"
   - If all done: suggest archiving (`openspec-archive-change`)
   - If paused: explain why and wait

**Output During Implementation**
```
## Implementing: <change-name>

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

**Output On Completion**
```
## Implementation Complete

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

All tasks complete! Ready to archive this change (openspec-archive-change).
```

**Guardrails**
- Keep going through tasks until done or blocked
- Always read the artifacts before starting
- If a 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 the `tasks.md` checkbox immediately after completing each task
- Pause on errors, blockers, or unclear requirements — don't guess
- Consult MCP/skills for SAP code; orchestrate via sub-agents for substantial work