spike

spike is a skill for Claude Code from strelov1/spec-driven-tdd. It costs 37 tokens per session (484 once invoked), scanned A, original, MIT.

A throwaway experiment that tests whether a risky technical idea can work before detailed planning begins. It ends with a verdict: validated, partly validated, or invalidated.

In plain words
What is it for?
Use it to test unproven approaches, external APIs, or other open feasibility questions with a small scratch script or one-off command.
Why use it?
It answers the hardest unknown cheaply, so an unworkable approach is rejected before time is spent building it.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the spec-driven-tdd plugin — 14 skills, 1 hook shipped together

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/strelov1/spec-driven-tdd/spike
Any agent
npx skills add strelov1/spec-driven-tdd --skill spike
Clone the repo
git clone --depth 1 https://github.com/strelov1/spec-driven-tdd

Made for: Claude Code.

Or install spec-driven-tdd, the plugin that ships this one along with the rest of its 14 skills, 1 hook.

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 spike

README.md
[![agentmods](https://agentmods.dev/badge/skills/strelov1/spec-driven-tdd/spike.svg)](https://agentmods.dev/skills/strelov1/spec-driven-tdd/spike)
Your own site
<a href="https://agentmods.dev/skills/strelov1/spec-driven-tdd/spike"><img src="https://agentmods.dev/badge/skills/strelov1/spec-driven-tdd/spike.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 484 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 5.1 $0.00037 $0.00484
Opus 5 $0.00018 $0.00242
Sonnet 5 $0.00007 $0.00097
Haiku 4.5 $0.00004 $0.00048

Measured 6d ago against content hash 6e29eb112ca9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

spike scanned grade A with 1 finding 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 6d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

(`/tmp`, a REPL, a one-off `curl`) — **never** inside the change's worktree.
skills/spike/SKILL.md · 44 lines

What it actually says

spike

A disposable feasibility experiment. When a change carries unproven technical risk — an untested approach, an external API, an open "is this possible?" — spike it before writing any OpenSpec artifacts. The point is to answer the risky question for the price of a script, so an unviable idea is killed cheaply.

Core principle: the code is throwaway. A spike that needs cleanup was over-built. Only the verdict survives.

When to use

Risk-gated, not mandatory. Spike only when feasibility is genuinely unclear. If the approach is obviously viable, skip straight to planning. Research enough to pick an approach, then spike the riskiest unknown first — there is no point prototyping the easy parts if the hard part does not work.

Process

  1. Decompose — frame 2–5 concrete feasibility questions (Given/When/Then), ordered by risk. The most dangerous unknown goes first.
  2. Align — show the questions and the plan; let the user trim before you write code.
  3. Build minimal — write the smallest runnable thing in a scratch location (/tmp, a REPL, a one-off curl) — never inside the change's worktree. Hardcode everything. No packaging, Docker, config, or build tooling. It is a spike.
  4. Observe — run it and capture the real output. A spike with no observable result proved nothing.
  5. Verdict — close with exactly one, plus a sentence of why:
    • VALIDATED — the approach works; proceed to plan the change.
    • PARTIAL — only a subset works; narrow scope to that subset, then plan.
    • INVALIDATED — the approach does not work; do not create the change.

After the spike

Discard the scratch code. Hand the verdict back to the caller — in the spec-driven-tdd Plan phase it gates whether /opsx:propose runs at all.

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. 6d ago First seen · 44 lines · 37 tokens per session scan A 6e29eb112ca9

Subscribe to this mod's changes

spike is a skill published in the GitHub repository strelov1/spec-driven-tdd (10 stars, last pushed 28d ago), licensed MIT. It adds 37 tokens to every session and 484 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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