What is deriving-journeys?

A skill for creating a journey.yaml file that describes a user interface flow introduced by a pull request, using the real running application to check selectors.

It helps inspect a pull request, identify its user-facing flow, verify the app is running, create a valid journey manifest, and save the planned deliverables in the target repository.

It grounds the proposed demo in the actual app and stops at a human review point before capture or rendering begins.

deriving-journeys — Skill for Claude Code by bnayahu

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 bnayahu/journeycast --skill deriving-journeys

Clone the repo

git clone --depth 1 https://github.com/bnayahu/journeycast

Made for: Claude Code.

Or install journeycast, the plugin that ships this one along with the rest of its 3 skills, 1 command.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/bnayahu/journeycast/deriving-journeys/github.svg)](https://agentmods.dev/skills/bnayahu/journeycast/deriving-journeys)

Your own site

<a href="https://agentmods.dev/skills/bnayahu/journeycast/deriving-journeys"><img src="https://agentmods.dev/badge/skills/bnayahu/journeycast/deriving-journeys/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/bnayahu/journeycast/deriving-journeys"><img src="https://agentmods.dev/badge/skills/bnayahu/journeycast/deriving-journeys.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 782 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 1 finding. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00059	$0.00782
Opus 5	$0.00030	$0.00391
Sonnet 5	$0.00012	$0.00156
Haiku 4.5	$0.00006	$0.00078

Measured 9d ago against content hash 0b77dc454280, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

deriving-journeys 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 9d 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.

2. **Confirm the app is running.** Ask the user for the app's base URL (default `http://localhost:3000`). Health-check it — e.g. `curl -sSf <baseUrl> -o /dev/null`. If it is not reachable, tell the user to start their ap

skills/deriving-journeys/SKILL.md · 38 lines

How it starts

The opening of the file, as written. The whole thing — 38 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Deriving journeys

Author a journey.yaml describing the UI journey a pull request introduces, grounded in the real app. This skill ends at an explicit human-edit gate — you draft, then stop.

Output location

Journeycast artifacts live in the target repository (the repo the PR belongs to, checked out locally) — never inside the journeycast clone. For PR <pr>, the convention is:

<target-repo>/docs/journeycast/pr-<pr>/ — the committed deliverables: journey.yaml, <feature>.mp4, <feature>.srt. Referred to below as $OUTDIR. Use the bare PR number (pr-1, not pr-0001).
out/pr-<pr>/ inside the journeycast clone — intermediate capture/render scratch (screenshots, manifest, .work). Gitignored via out/. Referred to below as $WORKDIR.

Resolve the target repo's local path from the PR (ask the user if it is ambiguous), then mkdir -p "$OUTDIR".

Steps

Gather PR context. Run gh pr view <pr> and gh pr diff <pr>; note the title, body, and the changed files. Infer which user-facing flow the PR adds or changes. Resolve $OUTDIR (see Output location).
Confirm the app is running. Ask the user for the app's base URL (default http://localhost:3000). Health-check it — e.g. curl -sSf <baseUrl> -o /dev/null. If it is not reachable, tell the user to start their app and stop. The engine drives a running app; it does not start one.
First-use setup (once per checkout). If engine/node_modules is absent, instruct: cd engine && npm install && npx playwright install chromium.
Probe for real selectors. Run node engine/capture.mjs --explore --url <baseUrl> --routes <comma,separated,routes> and read the JSON it prints. Prefer the data-testid / role / text selectors it reports over guesses.
Author journey.yaml. Write it to $OUTDIR/journey.yaml, conforming to skills/deriving-journeys/journey.schema.json. Use the scene kinds title, screen, action, callout, outro. Set meta (title/feature/pr/repo), app (baseUrl + viewport), narration (provider + voice), and steps. Write concise narration per step — one or two sentences.

Read the full file on GitHub · 38 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

journey.schema.json 3.8 KB

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.

9d ago First seen · 38 lines · 59 tokens per session scan A 0b77dc454280

Subscribe to this mod's changes

deriving-journeys is a skill published in the GitHub repository bnayahu/journeycast (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 59 tokens to every session and 782 once invoked, about $0.0003 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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deriving-journeys