Openspec Apply Change

---
name: openspec-apply-change
description: Implement tasks from an OpenSpec change. Use when the user wants to start implementing, continue implementation, or work through tasks.
allowed-tools: Bash(openspec:*)
license: MIT
compatibility: Requires openspec CLI.
metadata:
    author: openspec
    version: "1.0"
    generatedBy: "1.12.0"
---

Implement tasks from an OpenSpec change.

**Store selection:** If the user names a store (a store is a standalone OpenSpec repo registered on this machine) or the work lives in one, run `openspec store list --json` to discover registered store ids, then pass `--store <id>` on the commands that read or write specs and changes (`new change`, `status`, `instructions`, `list`, `show`, `validate`, `archive`, `doctor`, `context`, `schemas`, `view`). Once selected, treat `--store <id>` as sticky for the rest of the workflow. Every unscoped example of those commands below is shorthand: before running it, append the flag. For example, run `openspec status --change "<name>" --json --store "<id>"`, not the unscoped form shown below. Other commands do not take the flag. Hints printed by commands already carry the flag; keep it on follow-ups. Without a store, commands act on the nearest local `openspec/` root.

**Input**: Optionally specify a change name (e.g., `/opsx:apply add-auth`). If omitted, check if it can be inferred from conversation context. If vague or ambiguous you MUST prompt for available changes.

**Steps**

1. **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 ask the user to select one

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

2. **Check status to understand the schema**

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

    Parse the JSON to understand:
    - `schemaName`: The workflow being used (e.g., "spec-driven")
    - `planningHome`, `changeRoot`, and `actionContext`: planning scope and edit constraints
    - Which artifact contains the tasks (typically "tasks" for spec-driven, check status for others)

3. **Get apply instructions**

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

    This returns:
    - `contextFiles`: artifact ID -> array of concrete 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
    - Optional `context`: current required project instruction input from the selected root
    - Optional `operationGuidance`: current advisory guidance for apply

    **Handle states:**
    - If `state: "blocked"` (missing artifacts): show message, suggest using `/opsx:continue` (if it is not installed, run `openspec status --change "<name>" --json` to see the next artifact and `openspec instructions <artifact-id> --change "<name>" --json` for how to create it)
    - If `state: "all_done"`: congratulate, suggest archive
    - Otherwise: proceed to implementation

    Treat `context` as a required prompt-level input. Read and consider it, and
    apply relevant project facts, conventions, and constraints while implementing.
    Treat `operationGuidance` as optional additive advice. Read and consider every
    entry, and follow entries that are applicable and compatible with the built-in
    workflow.

    Keep both fields separate from CLI-returned state, missing artifacts, tasks,
    progress, `contextFiles`, and the built-in `instruction`. They are not
    evidence of task completion, do not replace the built-in instruction, and do
    not permit bypassing a blocked state. If context conflicts with the built-in
    instruction, an explicit user choice, or a CLI-controlled value, report the
    conflict and preserve the controlling value. If guidance is inapplicable or
    conflicts with those controlling inputs, do not follow it and explain why.
    These are prompt-level behavior contracts, not enforceable checks.

4. **Read context files**

    Read every file path listed under `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

    Do not copy `context` or `operationGuidance` verbatim into implementation
    files or planning artifacts unless the user separately asks for that content.

5. **Show current progress**

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

6. **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
    - A task needs work beyond what the spec and tasks describe, or you are tempted to drop, narrow, defer, or accept exceptions to specified behavior to make it fit → surface the added scope and ask; do not absorb it silently
    - Error or blocker encountered → report and wait for guidance
    - User interrupts

7. **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! You can archive this change with `/opsx:archive`.
```

**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
- When a task needs work beyond what the spec describes, surface the added scope and pause - never silently narrow, defer, or simplify away specified behavior
- Only mark a task `- [x]` when its specified behavior is fully implemented, not when it is partially done or deferred
- Use contextFiles from CLI output, don't assume specific file names
- Do not use context or operation guidance as proof that a task is complete
- Apply relevant project context; report conflicts with controlling workflow inputs
- Consider every guidance entry; explain any inapplicable or conflicting advice
- Do not copy runtime context or operation guidance into implementation files or planning artifacts
- Preserve CLI-controlled blocked/ready/all-done behavior and completion criteria

**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