Borrowing it
Nothing to install: this file belongs to foxzool/openlark. 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/foxzool/openlark/main/.agents/skills/openlark-formal-event-inbound/SKILL.mdgit clone --depth 1 https://github.com/foxzool/openlarkWrote 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/foxzool/openlark/openlark-formal-event-inbound)<a href="https://agentmods.dev/skills/foxzool/openlark/openlark-formal-event-inbound"><img src="https://agentmods.dev/badge/skills/foxzool/openlark/openlark-formal-event-inbound/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/foxzool/openlark/openlark-formal-event-inbound"><img src="https://agentmods.dev/badge/skills/foxzool/openlark/openlark-formal-event-inbound.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 | $0.00079 | $0.01711 |
| Opus 5.5 | $0.00032 | $0.00684 |
| Sonnet 5.5 | $0.00016 | $0.00342 |
| Haiku 4.5 | $0.00008 | $0.00171 |
Grade A, and why
openlark-formal-event-inbound 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 6d 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 — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Formal verification: HttpEventInbound handle
Read this cold mid-change. You do not need to know TLA+. Run the script, read the plain-language result, and only open the .tla file when the covered Rust steps changed.
When to use
Use this skill if your change touches any of:
| Path | Why |
|---|---|
crates/openlark-client/src/event_inbound/handler.rs |
handle, extract_payload, verify_sign, auth_challenge |
crates/openlark-client/src/event_inbound/crypto.rs |
decrypt_event, verify_inbound_signature (call sites / contract) |
crates/openlark-client/src/event_inbound/mod.rs |
exports / wiring of inbound |
formal/event_inbound/** |
the model or runner itself |
If none of those change, skip this skill.
Property (plain language)
Promise A — no unauthenticated dispatch: When encrypt_key is non-empty and skip_sign_verify is false, an event (not url_verification) must not reach dispatcher.dispatch_with_response unless the inbound signature is Good. Harm if broken: forged Feishu HTTP callbacks run bot handlers.
Promise B — challenge never dispatches as event: type == url_verification must finish via auth_challenge, never the event dispatcher. Harm if broken: challenge traffic is treated as a business event.
Promise C — verify before decrypt (intended, currently broken): Traffic that still needs a signature check and presents Missing/Bad signature must not call decrypt_event first. Harm if broken: unauthenticated clients force AES decrypt + JSON parse before reject (CPU / oracle cost).
Tool and why
TLA+ / TLC (model checker), not a Rust prover: the risk is the decision table of config × body shape × req type × signature × decrypt outcome. Unit tests cover happy paths; they do not enumerate every combination. There is no production code-level model checker for this pipeline. Crypto (AES/SHA256) is abstracted; TLC explores control-flow orders and input combinations up to the bound.
Pinned tool: tla2tools v1.8.0 (tla2tools.jar from the tlaplus GitHub release). Requires Java 17+ on PATH.
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.
- 6d ago First seen · 123 lines · 79 tokens per session scan A 4025fbf48022
openlark-formal-event-inbound is a skill published in the GitHub repository foxzool/openlark (108 stars, last pushed 3d ago), licensed Apache-2.0. It adds 79 tokens to every session and 1,711 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 2026-10-23.
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