Add claude-agent-sdk example

[opencolin]

Anthropic's own agent SDK was the one missing from the Agent frameworks table, beside Vercel AI SDK / LangChain / CrewAI / OpenAI Agents / LlamaIndex / smolagents. This adds it with Tenki as the execution backend.

The integration is tools: [] plus an in-process MCP server. Disabling every built-in tool is the point: left on, the SDK's Bash/Read/Write/Edit run on the machine that called query(), and the sandbox tools would be one option among several. With them off, bash, write_file, and read_file route to sandbox.exec, sandbox.writeFile, and sandbox.readFile, and the agent's entire execution surface is a microVM.

API checked against the installed @anthropic-ai/claude-agent-sdk@0.3.233 typings rather than guessed — tool(name, description, rawZodShape, handler) takes a bare shape (not z.object({...})), createSdkMcpServer({ name, version, tools }) returns an in-process server, and its tools are still namespaced mcp__tenki__* for allowedTools.

Verification

Ran node verify.mjs locally against the live API:

✓ claude-agent-sdk: write_file → bash python3 fib.py → 832040 → read_file → dispose

Exit code 0. It builds the real SDK tool definitions against a live sandbox and calls their handlers directly, no LLM: write_file returns wrote fib.py, bash runs python3 fib.py in the VM and returns exactly 832040, read_file round-trips the script. Real computed values, no truthiness checks.

agent.mjs also ran end to end on Node 24, with a live model turn:

→ mcp__tenki__write_file {"path":"fib.py","content":"def fib(n):\n    a, b = 0, 1\n    for _ in
→ mcp__tenki__bash {"command":"python3 fib.py"}
The 30th Fibonacci number is **832040**.
-rw-r--r-- 1 tenki tenki 136 Aug 17 05:13 fib.py

The agent reached the answer only through the Tenki-backed tools — it had no local ones — and the final ls is agent.mjs proving the artifact exists in the microVM and nowhere on the host.

Behaviours measured live, not assumed

• A tool handler that throws is caught by the SDK and delivered as an is_error tool result. Drove an agent at a missing path: it saw [not_found] read file failed: ... no such file or directory, reported it, and recovered — so read_file needs no try/catch.
• A tool result carries no exit status, so a command that fails after writing to stderr reads as success. bash now prefixes exit N on non-zero.

Sequencing

Based on examples/claude-code-sandbox (#20) rather than main, since both PRs add a row to the root README table. Rebased on it again after that PR's latest commit; GitHub will retarget this to main when #20 merges. Review the two commits as one stack, or #20 first.

Adds one row to Agent frameworks; touches nothing else outside examples/claude-agent-sdk/.