particle-velocity-slice

particle-velocity-slice is a skill for Claude Code, Codex from spedas/spedas_agent_kit. It costs 113 tokens per session (2,376 once invoked), scanned A, original, MIT.

A workflow for cutting a two-dimensional heatmap from a three-dimensional particle velocity distribution. It shows how particle speeds are arranged in a selected velocity plane.

In plain words
What is it for?
Use it to inspect an existing 3D ion or electron distribution, compare views with or without bulk-motion removal, and look for non-standard particle structure.
Why use it?
A 2D slice can reveal beams, rings, crescents, and uneven particle populations that averages or one-dimensional plots hide.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it to inspect an existing 3D ion or electron distribution, compare views with or without bulk-motion removal, and look for non-standard particle structure.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/spedas/spedas_agent_kit/particle-velocity-slice
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.

Any agent
npx skills add spedas/spedas_agent_kit --skill particle-velocity-slice
Clone the repo
git clone --depth 1 https://github.com/spedas/spedas_agent_kit

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for particle-velocity-slice

README.md
[![agentmods](https://agentmods.dev/badge/skills/spedas/spedas_agent_kit/particle-velocity-slice/github.svg)](https://agentmods.dev/skills/spedas/spedas_agent_kit/particle-velocity-slice)
Your own site
<a href="https://agentmods.dev/skills/spedas/spedas_agent_kit/particle-velocity-slice"><img src="https://agentmods.dev/badge/skills/spedas/spedas_agent_kit/particle-velocity-slice/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for particle-velocity-slice

Your own site · 80×15
<a href="https://agentmods.dev/skills/spedas/spedas_agent_kit/particle-velocity-slice"><img src="https://agentmods.dev/badge/skills/spedas/spedas_agent_kit/particle-velocity-slice.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 113 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,376 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 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 5.1 $0.00113 $0.02376
Opus 5 $0.00056 $0.01188
Sonnet 5 $0.00023 $0.00475
Haiku 4.5 $0.00011 $0.00238

Measured 8d ago against content hash 7850c2ae66e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

particle-velocity-slice 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.

.agents/plugins/spedas-codex/skills/particle-velocity-slice/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

2D velocity-space distribution slice (spd_slice2d)

The canonical IDL/Python SPEDAS spd_slice2d plot: cut a single 2D plane through a 3D particle velocity distribution and render it as a vx–vy heatmap. This is how you see beams, temperature anisotropy, ring/crescent distributions, and other non-Maxwellian structure that bulk moments average away and that 1D energy/pitch-angle spectra collapse. It is downstream of a real 3D distribution: it consumes a distribution artifact, it does not create one.

When to use

  • "Show me a 2D slice of the ion/electron distribution at in the BV plane."
  • "Is there a beam / crescent / ring in this distribution? Plot the velocity-space cut."
  • "Compare the distribution with and without bulk-velocity subtraction."
  • Any single-time (or short-window-averaged) velocity-space inspection of a 3D dist.

Do not use this for energy-time spectrograms or pitch-angle distributions (use compute_particle_spectra), for moments (use compute_particle_moments), or when you do not yet have a 3D distribution — build it first (see prerequisite below).

Prerequisite (hard dependency)

This skill requires a real 3D distribution object (the pyspedas particle distribution dict/array, per energy × theta × phi per time), not a tplot spectrogram. Produce it first with the particle-distribution bridge skill (build_particle_distribution_artifact, the #95 bridge): it loads the L2 particle product (a *-DIST 3D distribution, e.g. MMS FPI dis-dist/des-dist, MMS HPCA, or an ERG particle product) and emits a distribution artifact. Supported bridge converters today are MMS FPI/HPCA + ERG only — THEMIS ESA and PSP SPAN-i have no Python *_get_dist converter in pyspedas yet, so the bridge returns code="unsupported" for them; treat them as not-yet-available until upstream pyspedas exposes the converters. If you only have a spectrogram, stop — spd_slice2d cannot use it.

Tool chain (all existing)

particle-distribution bridge (build_particle_distribution_artifact) → small local slice2d call → write the vx–vy grid to a single .npzrender_tplot (one spectrogram-style panel), all inside a create_spedas_analysis_bundle. For BV/BE/perp planes and bulk subtraction you also need aligned B and bulk velocity time-series — fetch those with load_data_source / browse_data_parameters / fetch_data_product.

Read the full file on GitHub · 91 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 · 91 lines · 113 tokens per session scan A 7850c2ae66e2

Subscribe to this mod's changes

particle-velocity-slice is a skill published in the GitHub repository spedas/spedas_agent_kit (3 stars, last pushed 1mo ago), licensed MIT. It adds 113 tokens to every session and 2,376 once invoked, about $0.0006 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 2026-08-31.

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