feat: add secure-payments reference for hardening agent payments

[theyavuzarslan]

What

Adds a secure-payments.md reference and one routing row in SKILL.md that points to it.

Why

The existing references cover how to move money (send, trade, x402 pay). None cover the checks that should run before money moves when the amount, address, or endpoint came from somewhere the agent does not control (a web page, a tool result, a bazaar listing, another agent). The risk is concrete: if a recipient address or amount arrives inside untrusted text, nothing downstream re-checks it before the wallet spends.

What it adds

The reference sequences existing skill commands into a safe order and adds agent-side guardrails:

• Inspect an x402 endpoint with x402 details before paying, and check price, asset, chain, and pay-to against expectations.
• Pay with an explicit --max-amount per-payment cap.
• Provenance check for payment parameters from untrusted sources (allowlist, re-fetch, or human confirm).
• Session and per-minute budgets plus a kill switch, tracked in the agent's own code.
• An append-only audit log that records decisions, never secrets.

Scope

• New file: skills/agentic-wallet/references/secure-payments.md
• One added row in the SKILL.md routing table

The only literal command blocks are awal status, x402 details, and x402 pay --max-amount, all already permitted by the skill's allowed-tools. Budget, kill switch, and audit log are written as agent-side logic, not shell the skill runs, so nothing falls outside the existing tool policy. No change to any current reference.

Disclosure

I work on agent security at GoPlus Security, and I proposed a version of this pattern for Circle's agent wallet skill (circlefin/skills#35). This reference is rewritten for awal and the x402 bazaar, is vendor-neutral, and references no external product.

[cb-heimdall]

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