feat: add read-only Taskmarket provider

[PolarJunction]

Description

Adds a strictly read-only Taskmarket action provider to the Python coinbase-agentkit package.

The provider exposes two actions:

• list_tasks discovers public funded work using bounded filters.
• get_task inspects one validated task identifier.

The implementation uses the fixed public origin https://api.taskmarket.dev/api, disables redirects, requires HTTP 200 responses, converts six-decimal USDC base units into decimal strings, and labels requester-supplied descriptions as untrusted content. Minimum-reward filters reject precision beyond six decimal places rather than silently weakening the requested threshold.

The provider cannot create or connect a wallet, sign transactions, claim or bid on tasks, submit work, accept terms or spend funds. The colocated README also discloses inherited AgentKit action analytics.

This contribution was prepared with AI assistance and independently reviewed. No generated merge, acceptance or payment claim is made.

Tests

No wallet, chatbot or blockchain network is required because both actions are read-only calls to Taskmarket's public API.

Validated locally:

• 7 focused Taskmarket tests passed.
• Full Python package suite: 670 passed, 35 deselected.
• Ruff format and lint checks passed.
• Strict mypy checks passed for the provider, schemas and tests.
• git diff --cached --check passed before the signed commit.
• A live read-only public API call successfully listed and inspected funded work.
• An independent fail-closed review passed after redirect handling and USDC-precision findings from the first review were fixed.

Example import:

from coinbase_agentkit import taskmarket_action_provider

provider = taskmarket_action_provider()

Checklist

• Added documentation to all relevant README.md files
• Added a changelog entry

[cb-heimdall]

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