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.
npx agentmods add skills/mendix/web-widgets/openspec-proposenpx skills add mendix/web-widgets --skill openspec-proposegit clone --depth 1 https://github.com/mendix/web-widgetsWhat 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.
| Model | Per session | Once 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 |
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.
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
-
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.
-
Create the change directory
openspec new change "<name>"This creates a scaffolded change at
openspec/changes/<name>/with.openspec.yaml. -
Get the artifact build order
openspec status --change "<name>" --jsonParse 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
-
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 fileinstruction: Schema-specific guidance for this artifact typeoutputPath: Where to write the artifactdependencies: Completed artifacts to read for context
- Read any completed dependency files for context
- Create the artifact file using
templateas the structure - Apply
contextandrulesas constraints - but do NOT copy them into the file - Show brief progress: "Created "
b. Continue until all
applyRequiresartifacts are complete- After creating each artifact, re-run
openspec status --change "<name>" --json - Check if every artifact ID in
applyRequireshasstatus: "done"in the artifacts array - Stop when all
applyRequiresartifacts are done
c. If an artifact requires user input (unclear context):
- Use AskUserQuestion tool to clarify
- Then continue with creation
- Get instructions:
-
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-applyor ask me to implement to start working on the tasks."
Artifact Creation Guidelines
- Follow the
instructionfield fromopenspec instructionsfor each artifact type - The schema defines what each artifact should contain - follow it
- Read dependency artifacts for context before creating new ones
- Use
templateas the structure for your output file - fill in its sections - IMPORTANT:
contextandrulesare 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
- Do NOT copy
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
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.
- today First seen · 119 lines · 47 tokens per session scan A 586d02077eff
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.
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