specrails-core: Skill for Codex

.codex/skills/openspec-apply-change/SKILL.md

openspec-apply-change is a skill for Codex from fjpulidop/specrails-core. It costs 31 tokens per session (1,205 once invoked), scanned A, a copy of openspec-apply-change, MIT.

A task runner for implementing an OpenSpec change, which is a named set of planned software updates and their tasks.

In plain words
What is it for?
Use it to start or continue implementing a specific OpenSpec change. It also helps resolve which change to use when the request does not name one clearly.
Why use it?
It helps you choose the right change, inspect its workflow and instructions, and work through the listed implementation tasks without losing track of the plan.

Skill for Codex

Written for Codex: installed under .codex/. Also seen: names the AskUserQuestion tool.

This is fjpulidop/specrails-core's own configuration. It tells Codex how to work on specrails-core itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything specrails-core configures →

Reuse

Borrowing it

Nothing to install: this file belongs to fjpulidop/specrails-core. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/fjpulidop/specrails-core/main/.codex/skills/openspec-apply-change/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/fjpulidop/specrails-core

Made for: Codex.

Wrote this? Show the measurements

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README.md
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Per session 31 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,205 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod 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 5.1 $0.00031 $0.01205
Opus 5 $0.00015 $0.00602
Sonnet 5 $0.00006 $0.00241
Haiku 4.5 $0.00003 $0.00120

Measured 8d ago against content hash da3d97f3ea48, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

openspec-apply-change 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 8d ago.

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

This is a copy

100% identical to openspec-apply-change — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.codex/skills/openspec-apply-change/SKILL.md · 160 lines

How it starts

The opening of the file, as written. The whole thing — 160 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. 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 - 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

    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! 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?

Read the full file on GitHub · 160 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. 8d ago First seen · 160 lines · 31 tokens per session scan A da3d97f3ea48

Subscribe to this mod's changes

openspec-apply-change is a skill published in the GitHub repository fjpulidop/specrails-core (9 stars, last pushed yesterday), licensed MIT. It adds 31 tokens to every session and 1,205 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to openspec-apply-change, differing in 0 lines, and is treated as a copy.

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