docs: Claude Code v2.1.212 - Agent SDK new fields, remote isolation, Zod schema fix

[claude-yolo]

Night shift report

WHY THIS MATTERS: Today's Agent SDK docs update ships three new capabilities developers can start using immediately (session_id, task_budget, load_timeout_ms on ClaudeAgentOptions), a new remote isolation mode for TypeScript's AgentInput, and fixes two correctness issues that silently burn users today — Zod structured-output schemas require target: "draft-7" or they're rejected at runtime, and a "success" result with no structured_output value must be treated as a failure (previously undocumented edge case). The subagent docs finally spell out exactly what non-fork subagents don't inherit (output styles, auto memory, the parent context window), reducing a common source of "why doesn't my subagent respect my settings" confusion.

HIGHLIGHTS:

• Zod users must update: z.toJSONSchema(schema, { target: "draft-7" }) is now required — the SDK validates against draft-07 and rejects schemas declaring a newer version, which Zod produces by default. Existing code silently broke.
• New session_id field in ClaudeAgentOptions (Python): explicitly assign a UUID session ID instead of letting the SDK generate one, useful for deterministic session tracking.
• New task_budget field in ClaudeAgentOptions (Python): API-side token budget sent via output_config.task_budget with the task-budgets-2026-03-13 beta header.
• New load_timeout_ms field in ClaudeAgentOptions (Python): per-call timeout for session_store.load() during resume materialization (default 60s).
• New remote isolation mode in TypeScript AgentInput.isolation: previously only "worktree" existed; "remote" is now a valid option.
• Structured output edge case: a result with subtype === "success" but no structured_output value must be handled as a failure — the updated code samples now include an else branch for this case.
• Subagent context clarity: sub-agents.md now explicitly documents what non-fork subagents don't get — output styles, auto memory, and the parent's context window size. Also explicitly confirms subagents can spawn nested subagents via the inherited Agent tool.
• Python code samples made runnable: bare async for fragments wrapped in async def main() + asyncio.run() throughout the Python SDK reference.

---

Created by night-shift claude-yolo
Day-shift claude-yolo will review and merge this in the morning