Borrowing it
Nothing to install: this file belongs to cardstack/boxel. 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/cardstack/boxel/main/.claude/skills/secure-session/SKILL.mdgit clone --depth 1 https://github.com/cardstack/boxelWrote 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/cardstack/boxel/secure-session)<a href="https://agentmods.dev/skills/cardstack/boxel/secure-session"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/secure-session/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/cardstack/boxel/secure-session"><img src="https://agentmods.dev/badge/skills/cardstack/boxel/secure-session.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 | $0.00243 | $0.05684 |
| Opus 5.5 | $0.00097 | $0.02274 |
| Sonnet 5.5 | $0.00049 | $0.01137 |
| Haiku 4.5 | $0.00024 | $0.00568 |
Grade A, and why
secure-session 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 yesterday.
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 — 349 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Secure sessions (operators)
A secure session is a realm-server session signed in on the secure
origin, which card code can't reach. Why key changes need one, and the rules
that keep it out of card code's reach, are ADR 005
(docs/adr/005-authorize-key-changes-only-with-a-session-card-code-cant-reach.md);
read it before changing what a secure session gates or how one signs in. The
code is packages/realm-server/lib/secure-session.ts and
handlers/handle-secure-session.ts; the window's side is
packages/secure-origin/src/security/session.js and the sign-in components in packages/secure-origin/src/shell/sign-in/.
The claim and what it gates
A secure session is a realm-server JWT with user, sessionRoom and
secureSession: the id of a secure_sessions row. It works anywhere the
user's session does, and additionally:
| Gate | Requires |
|---|---|
POST /_key-write-tickets |
isSecureSession: the claim, naming a row of the token's user, not expired |
GET /_secure-session |
The same; answers 204, or 401 signed-out |
POST /_secure-session/login-token |
The same, and Origin the secure origin's; answers a single-use Matrix login token for the user |
Minting also still requires the request's Origin to be the secure origin's
or absent (the CLI). Only createSecureSessionJWT mints the claim (ADR 005
§1.2); tests/secure-session-test.ts asserts that createJWT and the realm
session minter in jwt.ts refuse it.
secure_sessions
| Column | Holds |
|---|---|
id |
UUID the token's secureSession claim names |
user_id |
Matrix user id |
client |
window (the secure window's own session) or cli (boxel keys) |
sign_in_proof |
What signed in: uia:<UIA session> for a password, google:<sha256 of the code> for Google; unique |
created_at |
timestamptz |
expires_at |
Seven days after sign-in (SECURE_SESSION_TTL_SECONDS); signing out sets it to now (see below) |
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.
- yesterday Changed · +90 lines · +11 tokens per session 14437c071bbf
- 3d ago Changed · +39 lines · +38 tokens per session b7982e4535bf
- 5d ago First seen · 220 lines · 194 tokens per session scan A dc2e4c64812a
secure-session is a skill published in the GitHub repository cardstack/boxel (27 stars, last pushed today), licensed MIT. It adds 243 tokens to every session and 5,684 once invoked, about $0.0010 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 2026-10-21.
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