Borrowing it
Nothing to install: this file belongs to greenpau/go-authcrunch. 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/greenpau/go-authcrunch/main/.codex/skills/authentication-portal-cross-device/SKILL.mdgit clone --depth 1 https://github.com/greenpau/go-authcrunchWrote 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/greenpau/go-authcrunch/authentication-portal-cross-device)<a href="https://agentmods.dev/skills/greenpau/go-authcrunch/authentication-portal-cross-device"><img src="https://agentmods.dev/badge/skills/greenpau/go-authcrunch/authentication-portal-cross-device/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/greenpau/go-authcrunch/authentication-portal-cross-device"><img src="https://agentmods.dev/badge/skills/greenpau/go-authcrunch/authentication-portal-cross-device.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 | $0.00044 | $0.03143 |
| Opus 5.5 | $0.00018 | $0.01257 |
| Sonnet 5.5 | $0.00009 | $0.00629 |
| Haiku 4.5 | $0.00004 | $0.00314 |
Grade A, and why
authentication-portal-cross-device 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 17d 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 — 243 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cross-Device Portal Login
Configuration and ownership
authn.CrossDeviceLoginConfig.Enabled is an explicit opt-in. Nil, omitted and
zero configurations disable both routes and login links. Assign the result of
pkg/authn/cross_device/parser.NewCrossDeviceLoginConfigFromDirectives(statements)
to PortalConfig.CrossDeviceLogin before construction. The parser accepts complete
enable cross-device login or disable cross-device login statements encoded
with cfgutil.EncodeArgs. Empty input disables; duplicate/conflicting settings,
extra tokens, joined keywords and multiline records fail without partial output
or echoed values. Collect all feature statements before parsing. JSON/XML/YAML
use cross_device_login with nested enabled; serialization preserves the opt-in.
Portal-owned implementation uses the cross_device_ filename prefix. The
embedded cross_device template and core/js/cross_device.js serve the flow.
The login template exposes the action inside user_actions for local and
provider-only configurations and beside the provider choices for mixed portals.
Filesystem login overrides must add the opt-in action themselves; the built-in
new template remains available unless overridden. The old /qrcode/login.png
bookmark still encodes ordinary portal navigation and is a separate feature.
The cross-device presentation contract owns step-specific headings, prominent matching codes, copy fallback, action layout, recovery labels, and optional Chrome screenshot capture. Built-in requester terminal states hide inactive controls and offer a fresh request; clipboard feedback remains separate from lifecycle status. Neither presentation changes nor recovery controls weaken explicit approval or revive a stopped interaction.
Browser and HTTP contract
All routes are relative to the portal mount; nested and root mounts work. Match
the complete route segment so mounts such as /cross-device-team/auth continue
to serve ordinary login and the transfer flow. Existing route namespaces retain
ownership of names such as /oauth2/cross-device and /assets/js/cross-device,
whether the feature is enabled or disabled. The /provider/<realm> namespace
also retains ownership; /provider/cross-device is a provider login, while
/cross-device/provider/... remains an invalid transfer endpoint. The optional
HTTP login capability does not supply cross-device completion evidence. An unknown child beneath the actual
transfer route must remain a 404, including children resembling other routes.
This is a browser login transfer, not an RFC 8628 device authorization endpoint.
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.
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.
- 17d ago Changed · +14 lines 747dc1539c01
- 26d ago Changed · +37 lines 781c5e02d2d0
- 28d ago Changed · +13 lines 30821793e182
- 29d ago Changed · +3 lines d959a3caca84
- 1mo ago First seen · 176 lines · 44 tokens per session scan A a52342c3fce9
authentication-portal-cross-device is a skill published in the GitHub repository greenpau/go-authcrunch (60 stars, last pushed 10d ago), licensed Apache-2.0. It adds 44 tokens to every session and 3,143 once invoked, about $0.0002 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 2026-10-04.
authentication-portal-cross-device compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| authentication-portal-cross-devicegreenpau/go-authcrunch | Skill | 60 | 10d ago | Apache-2.0 | A | 44 | Codex |
| imagegenopenai/codex | Skill | 133k | yesterday | Apache-2.0 | A | 113 | Codex |
| playwright-climicrosoft/playwright | Skill | 99k | yesterday | Apache-2.0 | A | 19 | Claude Code |
| local-ai-agentsmicrosoft/ai-agents-for-beginners | Skill | 79k | 4d ago | MIT | A | 200 | Claude Code, Codex |
| systematic-debuggingobra/superpowers | Skill | 313k | 3d ago | MIT | A | 21 | Claude Code |
| next-cache-components-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 95 | Claude Code |
| next-partial-prefetching-adoptionvercel/next.js | Skill | 143k | yesterday | MIT | A | 103 | Claude Code |