Add Nightmarket skill — API marketplace for AI agents

[streacy]

What this adds

A new Nightmarket skill in packages/skills/skills/nightmarket/ that gives Eliza agents the ability to discover and call paid third-party API services through the Nightmarket marketplace.

How it works

Nightmarket is an API marketplace where AI agents find and pay for third-party services (data enrichment, analytics, AI models, content generation, etc.). Every call settles on-chain in USDC on Base using the x402 payment protocol — no API keys or subscriptions needed.

The skill includes:

• SKILL.md — main skill doc with search, call, and payment flow instructions
• references/api.md — full API reference (endpoints, headers, error codes)
• references/crow-payments.md — CrowPay integration for automatic 402 payment handling
• references/mcp.md — optional MCP server setup for tool-based access

Why this is useful for Eliza

Eliza agents can use this skill to autonomously access any external API on the marketplace without the user needing to configure API keys or billing for each service individually. The agent searches, pays per-call in USDC, and gets the response — all within a single interaction.

This complements Eliza's existing plugin ecosystem by giving agents access to a growing marketplace of paid services through a single, standardized interface.

Integration

Follows the existing packages/skills/skills/ directory structure and SKILL.md format used by other Eliza skills.

Greptile Summary

This PR adds a new nightmarket skill — a documentation-only package teaching Eliza agents how to discover and pay for third-party APIs through the Nightmarket marketplace using the x402 payment protocol (HTTP 402 + on-chain USDC settlement on Base).

The documentation is generally well-organized, but there are four issues that need addressing before merge:

1. Wrong install targets: Both nightmarket and crow skill install commands reference Fallomai/skills instead of elizaos/eliza. After merge, users would be directed away from the official repo.

2. Inconsistent payment-signature encoding: crow-payments.md specifies base64(JSON.stringify(response_body)) encoding for the payment-signature header, but SKILL.md omits this detail. An agent reading only SKILL.md will construct a malformed header.

3. Wallet private key in config file: mcp.md instructs users to place raw WALLET_KEY in JSON config files without warning about the danger of accidentally committing it to version control.

Confidence Score: 2/5

• Not safe to merge as-is — install commands direct users to wrong repository, and agent-facing documentation has inconsistencies that will cause payment flows to fail or confuse implementers.
• Three verified issues require fixing: (1) both install commands point to an external repo, a functional correctness issue that will misdirect users after merge; (2) payment-signature encoding is specified in crow-payments.md but missing from SKILL.md, creating a logic gap; (3) wallet private key placement in config files without security warnings exposes users to accidental version-control leaks. These are all concrete, reproducible problems.
• packages/skills/skills/nightmarket/SKILL.md and packages/skills/skills/nightmarket/references/mcp.md need the most attention for the install commands and security warning respectively.

_{Last reviewed commit: d1e131d}

Greptile also left 4 inline comments on this PR.

_{(4/5) You can add custom instructions or style guidelines for the agent here!}

Context used:

• Rule from dashboard - Docs in README.md only; consolidate files; avoid bloat (source)

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[streacy]

Addressed all review feedback:

• Install paths fixed: Both skill install commands now reference elizaos/eliza instead of Fallomai/skills
• Payment encoding documented: Added base64 encoding specification to SKILL.md CrowPay section
• Security warning added: Added warning about never committing WALLET_KEY to version control in MCP config docs

Thanks for the thorough review!