Borrowing it
Nothing to install: this file belongs to divinevideo/divine-mobile. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/divinevideo/divine-mobile/main/.agents/skills/fastly-compute-well-known-spa-fallback/SKILL.mdgit clone --depth 1 https://github.com/divinevideo/divine-mobileWrote 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/divinevideo/divine-mobile/fastly-compute-well-known-spa-fallback)<a href="https://agentmods.dev/skills/divinevideo/divine-mobile/fastly-compute-well-known-spa-fallback"><img src="https://agentmods.dev/badge/skills/divinevideo/divine-mobile/fastly-compute-well-known-spa-fallback/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/divinevideo/divine-mobile/fastly-compute-well-known-spa-fallback"><img src="https://agentmods.dev/badge/skills/divinevideo/divine-mobile/fastly-compute-well-known-spa-fallback.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00151 | $0.02404 |
| Opus 5.5 | $0.00060 | $0.00962 |
| Sonnet 5.5 | $0.00030 | $0.00481 |
| Haiku 4.5 | $0.00015 | $0.00240 |
Grade A, and why
fastly-compute-well-known-spa-fallback 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 2mo 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.
- `curl -I https://yourdomain.com/.well-known/apple-app-site-association` shows `Content-Type: text/html` How it starts
The opening of the file, as written. The whole thing — 229 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fastly Compute: .well-known Files Intercepted by SPA Fallback
Problem
When using @fastly/compute-js-static-publish with SPA fallback configured (spaFile: "/index.html"), the PublisherServer.serveRequest() returns index.html with status 200 and Content-Type text/html for ANY path not found in the KV store. This includes /.well-known/apple-app-site-association and /.well-known/assetlinks.json, which iOS and Android require to be served as application/json.
Symptoms:
- iOS Universal Links don't work (Apple's verification fetches
.well-known/apple-app-site-associationand gets HTML) - Android App Links don't work (Google's verifier fetches
.well-known/assetlinks.jsonand gets HTML) curl -I https://yourdomain.com/.well-known/apple-app-site-associationshowsContent-Type: text/html- The files ARE published to KV (confirmed by
npm run fastly:publish) but still return HTML
Non-Obvious Root Causes
-
SPA fallback returns 200, not 404: The publisher's SPA mode returns
index.htmlwith HTTP 200 for missing paths. You cannot distinguish "file served" from "fallback served" by status code alone - you must inspect the Content-Type. -
apple-app-site-associationhas no file extension: The static publisher infers MIME type from file extension. With no extension, it cannot detectapplication/json, so even when the file IS published to KV, it may getapplication/octet-streamor be served incorrectly. -
includeWellKnown: trueinpublish-content.config.jsis necessary but not sufficient: It ensures the files are uploaded to KV, but doesn't prevent the SPA fallback from intercepting the requests, and doesn't fix the content-type for extension-less files. -
Both apex domain and subdomain handlers need the fix: If your Compute handler has separate code paths for subdomains vs apex, both paths must intercept
.well-known/requests before reaching the SPA fallback.
Solution
Step 1: Ensure Files Are Published
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.
- 2mo ago First seen · 229 lines · 151 tokens per session scan A 2c93c6bfbb80
fastly-compute-well-known-spa-fallback is a skill published in the GitHub repository divinevideo/divine-mobile (264 stars, last pushed today), licensed MPL-2.0. It adds 151 tokens to every session and 2,404 once invoked, about $0.0006 per session on Opus 5.5. 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 2026-08-30.
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