OPSX: Apply

A command for carrying out the implementation tasks defined in an OpenSpec change. OpenSpec is a structured way to describe a planned software change before coding it.

In plain words
What is it for?
Use it to select an OpenSpec change, inspect its workflow and instructions, and work through the listed implementation tasks.
Why use it?
It helps turn an approved change plan into code while checking which change and task list should be used.

Command for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/fonoster/fonoster/apply
Clone the repo
git clone --depth 1 https://github.com/fonoster/fonoster

Made for: Claude Code.

Per session 15 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,167 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00015 $0.01167
Opus 5 $0.00008 $0.00583
Sonnet 5 $0.00003 $0.00233
Haiku 4.5 $0.00002 $0.00117

Measured yesterday against content hash 3b96cfe79361, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

OPSX: Apply scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

8 near-identical copies found in the catalogue:

.claude/commands/opsx/apply.md · 156 lines

How it starts

The opening of the file, as written. The whole thing — 156 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement tasks from an OpenSpec change.

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 use the AskUserQuestion tool to let the user select

    Always announce: "Using change: " and how to override (e.g., /opsx:apply <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)
    • 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 /opsx:continue
    • If state: "all_done": congratulate, suggest archive
    • Otherwise: proceed to implementation

    Workspace guard: If status JSON reports actionContext.mode: "workspace-planning" and allowedEditRoots is empty, explain that full workspace apply is not supported in this slice. Treat linked repos and folders as read-only context, ask the user to select an affected area through an explicit implementation workflow, and STOP before editing files.

  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
  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
    • 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
  • Use contextFiles from CLI output, don't assume specific file names

Read the full file on GitHub · 156 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 156 lines · 15 tokens per session scan A 3b96cfe79361

Subscribe to this mod's changes

OPSX: Apply is a command published in the GitHub repository fonoster/fonoster (8,094 stars, last pushed 6d ago), licensed MIT. It adds 15 tokens to every session and 1,167 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.