Add blog post on LangGraph budget control for durable execution

[amavashev]

Summary

Add comprehensive blog post documenting budget control patterns for LangGraph workflows, focusing on the challenges introduced by durable execution, retries, and fan-out parallelism.

Changes

• New blog post: blog/langgraph-budget-control-durable-execution-retries-fan-out.md
  • Explains why durable execution changes the budget problem (checkpoints, retry compounding, fan-out multiplication)
  • Documents four specific budget problems: replayed nodes re-spending, retry storms, fan-out racing, and checkpoint-unaware budget state
  • Presents the reserve-commit pattern scoped to graph structure with run-level budgets, node-level reservations, and idempotent commits
  • Includes practical implementation example using Cycles callback handler with LangChain/LangGraph
  • Provides comparison tables showing cost impact with and without node-level budget control
  • Links to related documentation and guides

Key Content

• Real-world scenario: insurance claim processor with $270 in unplanned retry costs and $960 in fan-out branch costs
• Pattern explanation: run-level budget ceiling, node-level atomic reservations, idempotent cost settlement, retry-safe reconciliation, and fan-out budget scoping
• Implementation guidance for integrating budget controls with LangGraph through callback handlers
• Cross-references to related blog posts on budget control patterns, agent failures, and multi-tenant cost isolation

https://claude.ai/code/session_01CnvS6DLuYwRTjHdDYsnebk