openspec-apply-change

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., /openspec-apply-change 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: " and how to override (e.g., /openspec-apply-change <other>).

2. 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")
   • 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

   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 /openspec-continue-change (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