27 weeks · 54 posts · Written while building
Field notes from a personal AI OS in flight
Every Tuesday, an evergreen essay on what I'm learning while shipping DuranteOS. Every Friday, a dispatch from the week. Roughly 108,000 words and counting — for builders who'd rather watch the foundation get poured than read the press release.
Start here
If you're thinking about writing while building
After Twenty-Seven Weeks: What the Series Was For, and What I'm Building Next
If you're considering the founding cohort
The One Reference Customer Strategy: GTM for a Personal AI OS, Sketched Before the Customer Signs
If you want the architectural spine
The Decomposition Discipline I Am Trying to Codify Inside DOS
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W26 of 27
The Substrate Portability Pact: What DOS Refuses to Couple to, Even as the Harness Consolidates
Studio has been live for ninety-nine days. Last Tuesday Anthropic shipped Claude Code Routines — saved configurations that run on Anthropic infrastructure, on Anthropic's schedule, behind Anthropic's auth. The harness layer just consolidated into a first-party product. This essay is the architectural commitment I am writing in public, while the temptation to couple is fresh — three things DOS will refuse to bind to even when refusing costs me speed, and the test that catches the violation.
W25 of 27
The 90-Day Open-Weights Bakeoff: What Actually Routes Where in DOS Today
Studio has been routing across multiple substrates for ninety-five days. Seven providers integrated, ranging from Claude Sonnet 4.6 at one extreme to Google's open-weights Gemma 4 at the other. This essay is the empirical retrospective — which model handles which call type, where the routing logic sends each request by default, where the fallback kicks in, what the actual cost-per-quality numbers look like across roughly thirty thousand routed calls. Kent Beck on the smallest-experiment discipline applied to substrate selection. Andy Hunt and Dave Thomas on the Knowledge Portfolio reading: diversify, review, rebalance. Both applied to the moment routing decisions stop being intuition and become data.
W22 of 27
Routing by Sovereignty Class: The Architecture That Survives the Procurement Decade
Studio's gateway started the year routing on capability and cost. By March it routes on three additional axes — sovereignty class, partner channel, and policy posture — because the procurement decisions of the last six weeks made all three load-bearing for any product whose customers might be evaluated against federal, EU, or sector-tier procurement frameworks. This is the architecture I want to commit to before the next sovereign decision lands. Cockburn's hexagonal lens. Greg Young's event-sourced audit trail. Both applied to the moment routing decisions stop being optimization and become governance.
W21 of 27
MCP in Production: What Works When the Protocol Becomes the Boundary
Studio has been routing MCP-shaped tool calls in production for sixty-seven days. The protocol holds where I expected it to and leaks where I did not. This is the evergreen I want on the record before the next quarter of building, with Cockburn's hexagonal lens and Fowler's anti-corruption layer holding the framing. What MCP buys you in production, what it does not, and the three places I have already had to write provider-specific code despite the protocol's promise.
W18 of 27
Skills, Packs, and Hooks: The Three-Layer Model I'm Pulling DOS Toward
Anthropic shipped Skills as an open standard in December. The model I want DOS to settle on adds two more layers above and around it — Packs as Bounded-Context bundles of related Skills, and Hooks as the lifecycle layer that fires without invocation. Twenty-four weeks into DOS, with Studio shipping forty-six days ago and the open Skills spec now table stakes across coding-agent surfaces, this is the three-layer architecture I want to commit to before the layering decisions get baked the wrong way.
W15 of 27
Hexagonal in Practice: The Ports and Adapters I'm Pulling Studio Toward
Studio has been live for twenty-five days. The first three weeks of the codebase had route handlers calling Prisma directly with provider calls inline. The migration to a Hexagonal architecture started this past Monday and is the load-bearing decision for everything Studio is going to do across the next twelve providers, three storage backends, and unknown number of auth surfaces. This is the design essay I am writing as the migration is underway, with Cockburn on the principle and Fowler on the strangler-fig path that gets there without a rewrite.
W07 of 27
Credit-Metered API Gateways: The Pattern I Want Before I Have Anything to Meter
I do not have a Studio yet. I do not have a credit ledger yet. I do not have twelve providers behind a Bearer token yet. What I have is a clear picture of the gateway I want to build in the next 4-8 weeks, and the conviction that committing to the architecture now — before there is anything to retrofit — is cheaper than committing to it later. Here is the design, with Fowler on the routing layer and Greg Young on the ledger.
W05 of 27
Four Copies, One Source of Truth: The Sync Pattern I Want to Commit to Before It Hurts
Multi-copy systems are an architectural smell — until they are an architectural necessity. Eleven weeks into building DOS I can already see the duplication problem coming as soon as I start distributing skills outside my own machine. This is the design essay for the sync pattern I want to commit to before the smell gets bad — what Fowler and Feathers would say, and what I am going to mechanize early to avoid pain later.
W02 of 27
Memory Replaces Lock-In: Designing the Substrate of Personal AI
Lock-in via export friction is a 2010 strategy. The new moat is co-experience — accumulated context that lives in an append-only log of decisions, conversations, and corrections. This is the design essay for the memory layer I am about to build, before I build it. The architecture I think is right; the assumptions I will get to test.
The 27-week arc · A single body of work
Twenty-seven weeks. Two posts a week. Six months of writing while building.
Week
Tuesday evergreen
Friday dispatch
2025-10-28
The Agent Is the Product: Why Intelligence Replaces Interface
2025-10-31
Wrapper Wars: The Week Cursor, Windsurf, and MiniMax All Went Vertical
2025-11-04
Memory Replaces Lock-In: Designing the Substrate of Personal AI
2025-11-07
The Week the Substrate Caught Up: Kimi K2 Thinking Lands
2025-11-11
Why I Just Left a Steady Practice to Build a Personal AI Operating System
2025-11-14
The Week the Harness Ate the Model
2025-11-18
The Decomposition Discipline I Am Trying to Codify Inside DOS
2025-11-21
Antigravity, Gemini 3, Grok 4.1: The Week the Frontier Re-Rendered
2025-11-25
Four Copies, One Source of Truth: The Sync Pattern I Want to Commit to Before It Hurts
2025-11-28
Opus 4.5 Lands on Thanksgiving Week: Anthropic's Quiet Counter-Punch
2025-12-02
Plugin Architecture for Hooks: The Pattern I Want Before the Hook Becomes a God-Function
2025-12-05
The Runtime Is the Moat Now: Anthropic Buys Bun, Claude Code Hits a Billion
2025-12-09
Credit-Metered API Gateways: The Pattern I Want Before I Have Anything to Meter
2025-12-12
Three Frontier Models in 23 Days: Stop Picking a Winner, Start Picking a Router
2025-12-16
Sentinel, Sketched: Convention-Driven Onboarding Before I Build It
2025-12-19
The Spec Goes Public, the Substrate Goes to War: Skills Opens While Codex, Gemini Flash, and Nemotron Sprint
2025-12-23
Memory, Sketched: The Knowledge Graph I Was Designing Before MemPalace Shipped
2025-12-26
Christmas Wasn't Quiet: Open Weights Caught Up, Nvidia Bought Inference, Frontier Labs Bought Loyalty
2025-12-30
Council, Sketched: The Three-Round Debate Protocol I Want to Formalize Before I Build It
2026-01-02
The Practitioners' Year-End: While the West Took PTO, DeepSeek Shipped Architecture
2026-01-06
Altyaa's Wedge: The Brazilian-Portuguese SMB Bet Studio Is Pointed At
2026-01-09
Default Claude: Microsoft Flips the Switch as the Substrate Distributes by Default
2026-01-13
Builder's Compass: Two Years In, ~3,800 Subscribers, and What I've Learned Teaching Architecture
2026-01-16
The Agent Surface Splits in Two: Anthropic Goes Vertical While China Goes Substrate
2026-01-20
Failure Patterns, Sketched: The Bookkeeping Discipline I Want for the Agent's Mistakes
2026-01-23
The Rules Layer Solidifies: Constitution, Hardware, and Export Controls Land in One Week
2026-01-27
The One Reference Customer Strategy: GTM for a Personal AI OS, Sketched Before the Customer Signs
2026-01-30
Vertical Integration Eats Horizontal AI: Maia, Meta's Capex, and Anthropic-ServiceNow
2026-02-03
Hexagonal in Practice: The Ports and Adapters I'm Pulling Studio Toward
2026-02-06
Coding Becomes the Flagship: Opus 4.6 and GPT-5.3-Codex Land the Same Day
2026-02-10
TDD for AI Agents, Sketched: The Translation I Want to Commit to Before the Eval Suite Exists
2026-02-13
The Bifurcation Hardens: Anthropic's $380B Meets China's Open-Weights Frontier
2026-02-17
Refactoring the Hook Pipeline: The Fowler Walkthrough I'm Three Refactorings Into
2026-02-20
The Sonnet Window: Free-Tier Skills, Code Security, and the Race for Agentic Primitives
2026-02-24
Skills, Packs, and Hooks: The Three-Layer Model I'm Pulling DOS Toward
2026-02-27
The Moat Above the Model: Distillation, Mobile Coding, and MCP Battlegrounds
2026-03-03
The Knowledge Portfolio for an Indie Founder Building in Public, Audited at Week 25
2026-03-06
Procurement Is the New Benchmark: OpenAI Wins the DoW While Anthropic Gets Banned
2026-03-10
Six Months of DOS: What Changed, What Endured, What Surprised
2026-03-13
The Counter-Sovereignty Move: Anthropic Sues, Then Diversifies
2026-03-17
MCP in Production: What Works When the Protocol Becomes the Boundary
2026-03-20
Cursor Becomes a Model Lab: Composer 2 and the Unbundling at the Agent Layer
2026-03-24
Routing by Sovereignty Class: The Architecture That Survives the Procurement Decade
2026-03-27
The Injunction the Pentagon Won't Honor: Anthropic Wins, the State Defies
2026-03-31
Sentinel's First Scan: What the Convention Catalog Found Across Eleven Projects
2026-04-03
The Agent Stack Swallows the IDE, the IPO, and the Courtroom
2026-04-07
Forking MemPalace: The 48-Hour Integration Retro
2026-04-10
Project Glasswing: When the Frontier Bifurcates on Safety
2026-04-14
The 90-Day Open-Weights Bakeoff: What Actually Routes Where in DOS Today
2026-04-17
Routines Eat the Workflow: The Harness Becomes the Product