scenario

A command for adding behaviour-driven development scenarios to an existing TriadJS endpoint or channel. Behaviour-driven development, or BDD, describes expected behaviour as Given, When, and Then steps.

In plain words
What is it for?
It is for locating an endpoint or channel, setting up test data and requests, and writing scenarios that describe expected outcomes.
Why use it?
It helps test business behaviour in a consistent format while restricting assertions to phrases the project's parser understands.

Command

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 commands/justhamade/triadjs/scenario
Clone the repo
git clone --depth 1 https://github.com/justhamade/triadjs
Per session 34 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 866 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00034 $0.00866
Opus 5 $0.00017 $0.00433
Sonnet 5 $0.00007 $0.00173
Haiku 4.5 $0.00003 $0.00087

Measured 2d ago against content hash 2067366ee8bf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

scenario 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 2d 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.

plugin/commands/scenario.md · 58 lines

How it starts

The opening of the file, as written. The whole thing — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Load the triad-behaviors skill — it carries the authoritative assertion phrase table, fixture syntax, and scenario.auto() reference. Do NOT invent phrases — unrecognized strings fail as "Unrecognized assertion".

Add behavior scenarios to an existing endpoint or channel based on the user's description ($ARGUMENTS).

Steps

  1. Locate the target endpoint or channel. If the user gives a name, grep for name: 'thatName'. If they describe the resource, find the matching file in src/endpoints/ or src/channels/.

  2. Understand the business intent first. A scenario name should describe business intent, not mechanics:

    • Good: "Duplicate pet names are rejected within the same species"
    • Bad: "POST /pets returns 409 when name is taken"
  3. Write the .given() stage — seed fixtures via .setup(async services => { return { foo: ... } }) if the scenario depends on existing state, or use .fixtures({...}) for static values.

  4. Set the request.body(...), .params(...), .query(...), .headers(...). Use {placeholder} tokens to interpolate fixtures (e.g. .params({ id: '{petId}' })).

  5. Write the .when() narrative — a short string describing the action. This flows to Gherkin but doesn't affect test execution.

  6. Write the .then() and .and() assertionsevery phrase must match a row in the phrase table (see triad-behaviors skill):

    • response status is <N>
    • response body matches <ModelName>
    • response body has <path> "<string>" — double quotes, never single
    • response body has <path> <number>
    • response body has <path> true / false
    • response body has length <N>
    • response body is an array
    • response body is empty (for 204/t.empty() responses)
    • response body has code "<CODE>"
  7. For channels, use channel phrases instead:

    • <client> receives a <messageType> event
    • all clients receive a <messageType> event
    • <client> does not receive a <messageType> event
    • <client> receives a <messageType> with <field> "<value>"
    • connection is rejected with code <N>
  8. Consider adding ...scenario.auto() at the end of the behaviors array if it's not already there — it generates missing-field/boundary/enum/type scenarios from the schema constraints for free.

  9. Run triad test --filter <name> to verify every new scenario parses, seeds correctly, and passes.

Read the full file on GitHub · 58 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. 2d ago First seen · 58 lines · 34 tokens per session scan A 2067366ee8bf

Subscribe to this mod's changes

scenario is a command published in the GitHub repository justhamade/triadjs (23 stars, last pushed 4mo ago), licensed MIT. It adds 34 tokens to every session and 866 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 2026-08-30.