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 existential-birds/beagle --skill remix-v2-error-boundaries-reviewgit clone --depth 1 https://github.com/existential-birds/beagleWrote 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/existential-birds/beagle/remix-v2-error-boundaries-review)<a href="https://agentmods.dev/skills/existential-birds/beagle/remix-v2-error-boundaries-review"><img src="https://agentmods.dev/badge/skills/existential-birds/beagle/remix-v2-error-boundaries-review/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/existential-birds/beagle/remix-v2-error-boundaries-review"><img src="https://agentmods.dev/badge/skills/existential-birds/beagle/remix-v2-error-boundaries-review.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 | $0.00069 | $0.02438 |
| Opus 5.5 | $0.00028 | $0.00975 |
| Sonnet 5.5 | $0.00014 | $0.00488 |
| Haiku 4.5 | $0.00007 | $0.00244 |
Grade A, and why
remix-v2-error-boundaries-review 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 1mo 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 — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Remix v2 Error Boundaries Code Review
Targets TypeScript route modules importing from @remix-run/*. No sibling
knowledge skill exists for this topic; the canonical mental model is
summarized inline below and expanded in references/.
v2 Boundary Model (read first)
Remix v2 unified v1's CatchBoundary + ErrorBoundary into a single
ErrorBoundary route-module export. The framework calls it for both
thrown Responses (e.g. throw new Response(...), throw json(...))
and thrown runtime errors (loader/action/render exceptions). Inside
the boundary you read the value with the useRouteError() hook, then
narrow in this order:
isRouteErrorResponse(error)→ it was a thrownResponse; readerror.status,error.statusText,error.data.error instanceof Error→ real runtime error; readerror.message.- else → unknown thrown value; render a generic fallback.
The boundary takes no props. CatchBoundary, useCatch, and the
future.v2_errorBoundary flag are all gone — finding any of them is a
v1 holdover. Errors render the nearest ErrorBoundary and bubble to
the root if none exists; the root boundary remounts the whole document,
so it must render <Meta />, <Links />, and <Scripts />. Only
thrown loader/action results reach the boundary — a return json(...)
with a 4xx status is a successful loader, not an error. Server-side
runtime errors also flow through an optional entry.server.tsx
handleError export (thrown Responses do not).
Quick Reference
| Issue Type | Reference |
|---|---|
Missing route ErrorBoundary, props-on-boundary, narrowing-only instanceof Error, narrowing-only isRouteErrorResponse |
references/boundary-shape.md |
Return-instead-of-throw 4xx/5xx, swallowing error.data, throwing strings, missing handleError |
references/throw-response.md |
Missing root boundary, root boundary without <Meta />/<Links />/<Scripts />, useLoaderData() in root boundary |
references/root-boundary.md |
CatchBoundary export, useCatch import, v2_errorBoundary future flag |
references/v1-holdovers.md |
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.
- 1mo ago First seen · 145 lines · 69 tokens per session scan A c2a2e1b1582c
remix-v2-error-boundaries-review is a skill published in the GitHub repository existential-birds/beagle (82 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 69 tokens to every session and 2,438 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-16.
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