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 davidteren/hotwire-codex-skills --skill rails-8-upgradegit clone --depth 1 https://github.com/davidteren/hotwire-codex-skillsWrote 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/davidteren/hotwire-codex-skills/rails-8-upgrade)<a href="https://agentmods.dev/skills/davidteren/hotwire-codex-skills/rails-8-upgrade"><img src="https://agentmods.dev/badge/skills/davidteren/hotwire-codex-skills/rails-8-upgrade/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/davidteren/hotwire-codex-skills/rails-8-upgrade"><img src="https://agentmods.dev/badge/skills/davidteren/hotwire-codex-skills/rails-8-upgrade.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 | $0.00120 | $0.00887 |
| Opus 5 | $0.00060 | $0.00443 |
| Sonnet 5 | $0.00024 | $0.00177 |
| Haiku 4.5 | $0.00012 | $0.00089 |
Grade A, and why
rails-8-upgrade 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 11d 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 — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Rails 7 → 8 upgrade
Two things kill time in a 7→8 upgrade: deciding what to bump vs defer, and a
flaky route-helper test that Rails 8's LazyRouteSet introduces and that hides
behind single green test runs. This skill handles both.
Read references/rails-7-to-8.md for the full checklist and the why.
When to use
- Bumping
rails7.x → 8.x, or checking whether an app is ready. - Tests started flaking after a Rails 8 bump with
undefined method 'login_path'/'root_path'in unrelated controllers; serial runs stay green. - Reviewing a PR that adds/edits a
draw_test_routes-style route helper.
1. Pre-flight audit (read-only)
scripts/upgrade_audit.sh path/to/app
Reports: Ruby/Rails versions (+ flags a Gemfile.lock RUBY VERSION mismatch that
makes bundle refuse), config.load_defaults vs Rails major, presence of a
new_framework_defaults_*.rb, known-risky gems (notably pagy <6 with custom
pagy view helpers — a real porting cost), and whether the test suite uses the
flaky route pattern. Changes nothing.
2. The recommended path
- Baseline green on current versions first (a bisectable starting point).
- Bump
rails ~> 8.xand Ruby; leaveconfig.load_defaultswhere it is (run new library code with old framework behavior — low risk). bundle update; only hand-pin where a transitive conflict forces it.- Run the suite ≥6× (parallel flakes hide — see below). Boot the server, check a public (200) and a protected (401/redirect) route.
- Flip framework defaults separately later, via
config/initializers/new_framework_defaults_8_1.rb, one line at a time.
3. The LazyRouteSet route-test flake (the expensive one)
If the suite appends test-only routes via a helper that toggles
Rails.application.routes.disable_clear_and_finalize, Rails 8 makes it flaky under
parallel runs. Detect it:
scripts/lint_route_test_helper.sh path/to/app
It checks the helper (a) materializes the LazyRouteSet
(reload_routes_unless_loaded) before setting the flag, (b) resets the flag
in an ensure, (c) doesn't use the finalize! dead-end, and (d) every
draw_test_routes caller has a teardown { reload_routes! }. Exits non-zero on
risk and prints the fix.
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.
- 11d ago First seen · 72 lines · 120 tokens per session scan A be91bcd553a0
rails-8-upgrade is a skill published in the GitHub repository davidteren/hotwire-codex-skills (3 stars, last pushed 2mo ago), licensed MIT. It adds 120 tokens to every session and 887 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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