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 skills add zarpay/rails-template --skill rails-activity-timelinegit clone --depth 1 https://github.com/zarpay/rails-templateWrote 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.
[](https://agentmods.dev/skills/zarpay/rails-template/rails-activity-timeline)<a href="https://agentmods.dev/skills/zarpay/rails-template/rails-activity-timeline"><img src="https://agentmods.dev/badge/skills/zarpay/rails-template/rails-activity-timeline/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.
<a href="https://agentmods.dev/skills/zarpay/rails-template/rails-activity-timeline"><img src="https://agentmods.dev/badge/skills/zarpay/rails-template/rails-activity-timeline.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00041 | $0.01556 |
| Opus 5 | $0.00020 | $0.00778 |
| Sonnet 5 | $0.00008 | $0.00311 |
| Haiku 4.5 | $0.00004 | $0.00156 |
Grade A, and why
rails-activity-timeline 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 10d 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.
How it starts
The opening of the file, as written. The whole thing — 209 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Rails Activity Timeline
Add a polymorphic activity timeline with live Turbo Stream updates to any Rails model. Track field changes, status transitions, comments, attachments, and more with configurable icons and colors per action type.
When to Use This Skill
Invoke this skill when:
- Adding an activity/audit timeline to any Rails model
- Tracking field changes, status transitions, comments, or attachments
- Displaying live-updating activity feeds via Turbo Streams
- Auto-logging lifecycle events on child/associated models
- Building activity feeds with configurable icons and colors
Architecture Overview
The system is built around four components:
ActivityEventmodel (polymorphic) — the core event recordActivityTrackableconcern — auto-logs child model lifecycle events on a parent's timeline- Shared timeline partial — renders a vertical timeline with Turbo Stream live updates
- Display configuration — icon SVG path + accent color per action type, kept in the model
Key Associations (on ActivityEvent)
belongs_to :trackable, polymorphic: true # required — parent entity whose timeline this belongs to
belongs_to :subject, polymorphic: true, optional: true # related entity being acted upon
belongs_to :user, optional: true # who performed the action
Generic Action Set
ACTIONS = %w[
created updated destroyed
field_updated status_changed
comment_added
attachment_added attachment_removed
assigned unassigned
relationship_added relationship_removed
tag_added tag_removed
].freeze
Add domain-specific actions as needed (e.g., published, approved, merged). Just add them to ACTIONS and the DISPLAY hash.
Core Patterns
1. Setup from Scratch
Migration, full ActivityEvent model, ActivityTrackable concern, and prerequisites.
See: references/setup.md
2. Turbo Stream Broadcasting
Stream naming convention, broadcast methods, partial routing, shared timeline partial, and event partial.
What ships with it
4 files 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.
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.
- 10d ago First seen · 209 lines · 41 tokens per session scan A 295288883cfd
rails-activity-timeline is a skill published in the GitHub repository zarpay/rails-template (9 stars, last pushed 29d ago), licensed MIT. It adds 41 tokens to every session and 1,556 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 2026-08-31.
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