openspec-propose

Propose a new change with all artifacts generated in one step. Use when the user wants to quickly describe what they want to build and get a complete proposal with design, specs, and tasks ready for implementation.

Skill for Claude CodeCodex

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 skills/mendix/web-widgets/openspec-propose
Any agent
npx skills add mendix/web-widgets --skill openspec-propose
Clone the repo
git clone --depth 1 https://github.com/mendix/web-widgets

Made for: Claude Code, Codex.

Per session 47 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,046 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown 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 $0.00047 $0.01046
Opus 5 $0.00023 $0.00523
Sonnet 5 $0.00009 $0.00209
Haiku 4.5 $0.00005 $0.00105

Measured today against content hash 586d02077eff, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

openspec-propose 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 today.

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.

.agents/skills/openspec-propose/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Propose a new change - create the change and generate all artifacts in one step.

I'll create a change with artifacts:

  • proposal.md (what & why)
  • design.md (how)
  • tasks.md (implementation steps)

When ready to implement, run /opsx-apply


Input: The user's request should include a change name (kebab-case) OR a description of what they want to build.

Steps

  1. If no clear input provided, ask what they want to build

    Use the AskUserQuestion tool (open-ended, no preset options) to ask:

    "What change do you want to work on? Describe what you want to build or fix."

    From their description, derive a kebab-case name (e.g., "add user authentication" → add-user-auth).

    IMPORTANT: Do NOT proceed without understanding what the user wants to build.

  2. Create the change directory

    openspec new change "<name>"
    

    This creates a scaffolded change at openspec/changes/<name>/ with .openspec.yaml.

  3. Get the artifact build order

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

    Parse the JSON to get:

    • applyRequires: array of artifact IDs needed before implementation (e.g., ["tasks"])
    • artifacts: list of all artifacts with their status and dependencies
  4. Create artifacts in sequence until apply-ready

    Use the TodoWrite tool to track progress through the artifacts.

    Loop through artifacts in dependency order (artifacts with no pending dependencies first):

    a. For each artifact that is ready (dependencies satisfied):

    • Get instructions:
      openspec instructions <artifact-id> --change "<name>" --json
      
    • The instructions JSON includes:
      • context: Project background (constraints for you - do NOT include in output)
      • rules: Artifact-specific rules (constraints for you - do NOT include in output)
      • template: The structure to use for your output file
      • instruction: Schema-specific guidance for this artifact type
      • outputPath: Where to write the artifact
      • dependencies: Completed artifacts to read for context
    • Read any completed dependency files for context
    • Create the artifact file using template as the structure
    • Apply context and rules as constraints - but do NOT copy them into the file
    • Show brief progress: "Created "

    b. Continue until all applyRequires artifacts are complete

    • After creating each artifact, re-run openspec status --change "<name>" --json
    • Check if every artifact ID in applyRequires has status: "done" in the artifacts array
    • Stop when all applyRequires artifacts are done

    c. If an artifact requires user input (unclear context):

    • Use AskUserQuestion tool to clarify
    • Then continue with creation
  5. Show final status

    openspec status --change "<name>"
    

Output

After completing all artifacts, summarize:

  • Change name and location
  • List of artifacts created with brief descriptions
  • What's ready: "All artifacts created! Ready for implementation."
  • Prompt: "Run /opsx-apply or ask me to implement to start working on the tasks."

Artifact Creation Guidelines

  • Follow the instruction field from openspec instructions for each artifact type
  • The schema defines what each artifact should contain - follow it
  • Read dependency artifacts for context before creating new ones
  • Use template as the structure for your output file - fill in its sections
  • IMPORTANT: context and rules are constraints for YOU, not content for the file
    • Do NOT copy <context>, <rules>, <project_context> blocks into the artifact
    • These guide what you write, but should never appear in the output

Guardrails

  • Create ALL artifacts needed for implementation (as defined by schema's apply.requires)
  • Always read dependency artifacts before creating a new one
  • If context is critically unclear, ask the user - but prefer making reasonable decisions to keep momentum
  • If a change with that name already exists, ask if user wants to continue it or create a new one
  • Verify each artifact file exists after writing before proceeding to next

Read the full file on GitHub · 119 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. today First seen · 119 lines · 47 tokens per session scan A 586d02077eff

Subscribe to this mod's changes

openspec-propose is a skill published in the GitHub repository mendix/web-widgets (40 stars, last pushed today), licensed Apache-2.0. It adds 47 tokens to every session and 1,046 once invoked, about $0.0002 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 2026-09-01.