Swapping Tools Mid-Conversation Without Losing Your Prompt Cache
Tools can now be added and removed between turns, but the tool block sits at the very front of the cache prefix. I measured 12 mutation patterns with fingerprints and built a stable-core plus volatile-tail registry with a guard that refuses unsafe changes.
Rebuilding a Remote MCP Server That Never Needed Mcp-Session-Id
The MCP spec release candidate drops the session header. Here is how I audited my own remote server for session coupling and moved it to signed cursors, with measurements.
Building a Recurring Billing SaaS with Claude API and Stripe — From Architecture to Production
A complete architecture guide for building a SaaS product powered by Claude API with Stripe recurring billing. Covers usage metering, tiered pricing, webhook handling, and production deployment patterns.
Reading the Claude apps gateway Announcement, I Rebuilt My Indie-Scale Control Plane
The self-hosted Claude apps gateway is a control-plane/data-plane separation you can scale down. Per-app cost attribution, model allowlists, and fail-closed spend caps, implemented as a small Cloudflare Workers proxy.
Productionizing a Claude Design Prototype — Single Source, CI, and OGP Auto-Generation
Turn a Claude Design prototype into something that survives production with Claude Code. The call to keep the generated runtime as your foundation, separating logic with a mixin, a single-source data design around a ledger CSV, and CI auto-updates with real-browser OGP capture — implementation included.
When a Model Disappears Without Warning: A State Machine for Retirement, Withdrawal, and Overload
A model can become unusable in hours for reasons that have nothing to do with a technical outage. This guide models three distinct flavors of 'unavailable'—retirement, withdrawal, and transient overload—as one availability state machine, with a router that keeps automated pipelines running. Working TypeScript and Python included.
Context Budgets for Nested Subagents: Designing Contracts So 5-Level Delegation Doesn't Lose Quality
Once subagents could nest, deeper delegation made summaries thinner and reruns more frequent. Here is how I rebuilt quality by adding four contracts between layers: token budgets, a handoff schema, failure isolation, and an independent grader.
An Anti-Corruption Layer for Claude API Models — Keeping Generation Changes Out of Your Business Logic
Hard-coding model strings into business logic means production breaks quietly every time a generation is retired. Here is an anti-corruption layer that separates logical roles from physical model IDs, with working TypeScript and Python, migration costs, and the judgment calls behind it.
Guard Your Agent's Destructive Operations with Pre- and Post-condition Contracts
A design for wrapping an autonomous agent's writes in deterministic pre- and post-condition checks. A contract gate stops the destructive operations that better prompts can never reliably prevent.
Three State-Passing Patterns for Claude Code Subagents — Lessons from 4 Months of Automated Blog Pipelines
JSON files, environment variables, and context bundles — three ways to hand state between Claude Code subagents, compared with four months of production data and clear guidance on when to pick each.
Allocating the 200K Context Window in Claude API — Budgeting System, Tools, Memory, and History in Production
Treat Claude API's 200K context as a budget rather than an open shelf. A TypeScript-backed allocation architecture that carves system, tools, memory, history, and headroom into explicit envelopes — built and tuned in a wallpaper app earning real ad revenue.
Claude Code Sub-agent Patterns — Designing Autonomous Task Decomposition and Parallel Execution
Dissect Claude Code's internal Sub-agent architecture and learn concrete design patterns for task decomposition, parallel execution, and result merging in your own projects.