100ms rule and offline‑first architecture

From acquisition carve-outs to 100ms interaction rules: Engineering velocity through team clarity, not tool proliferation

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Outline How do you maintain execution velocity while building quality products? Loïc Houssier (CTO of Superhuman Mail, formerly Superhuman) offers a contrarian perspective: the answer isn't better tools or frameworks—it's radical clarity about team missions and strategic alignment.

With experience spanning French defense contractors (Orange, Thales), navigating DocuSign's complex French acquisition, and now steering Superhuman through its Grammarly acquisition/rebrand, Loïc brings a unique European-to-SF perspective on technical leadership.

Key insights for engineering leaders:

Execution & Velocity • PR per engineer per week as the "less bad" metric - track trends, not absolutes across teams • Clarity drives speed: clear team missions eliminate dependency bottlenecks and headquarters approval loops • Most velocity gains come from strategy clarity, not tooling improvements • Vertical team alignment: minimize cross-team dependencies by organizing around experiences (calendar team, compose team) • Focus quarterly: solve one major problem per quarter (velocity this quarter, quality next quarter)

Technical Architecture Decisions • Monorepo philosophy: resist microservices until genuine pain necessitates splitting • 100-millisecond interaction rule: every UI interaction must complete under 100ms • Offline-first architecture: sync happens in background, all actions execute locally • Gmail/Outlook API integration over IMAP for modern email clients • Modulith with domain-driven design over distributed microservices

Team Organization • Guild structure: formalize existing technical conversations (iOS guild, backend guild, AI guild) • Guild leaders surface quarterly problems and negotiate engineering time with product • Platform team + vertical feature teams = minimal dependencies • Full-stack teams owning specific experiences prevent feature factory mentality • Aligned autonomy: clear objectives, flexible execution methods

Framework Skepticism • Spotify model: "mostly marketing" according to actual Spotify engineers • GitLab remote-first: ~70% there, not the paradise portrayed • Context matters more than best practices from big tech • Apply frameworks as inputs, not blueprints - adapt to your specific context • Agile manifesto written by senior architects who knew each other - doesn't translate directly to teams fresh from college

Product & Design Philosophy • Laser-focused personas (professionals with heavy email volume) vs. Gmail's everyone approach • Four hours per week user time savings from better email UX • Design-centric like Linear: quality experience for narrow audience beats mediocre experience for everyone • Promotion frameworks should align with product goals: bake quality into career ladders if quality matters

Acquisition Integration • DocuSign French carve-out: Ministry of Finance blocked some assets, created split structure • Execution during acquisition demonstrates team value beyond revenue/customers • French labor law calculated as risk, not blocker - opportunity cost of not entering EU market • Smooth landings possible: kept redundant roles due to EU market subtleties

Cultural Observations • US mindset: "we might die tomorrow" drives urgency vs. EU "we're already successful" complacency
• European social safety nets enable higher risk-taking than perceived - losing your job in France is manageable • US risk-taking constrained by healthcare costs, college tuition, lack of safety net • Europeans are "grumpy" seeing empty glass, Americans see half full with optimism

Chapters:

[00:51] Superhuman, Grammarly, and the rebrand to Superhuman Mail
[01:47] Why Grammarly became Superhuman: AI-native productivity suite vision
[06:18] Career journey: Math PhD track to security researcher at Orange and Thales
[08:18] Submarines and defense contracts: Building the muscle to learn deep tech fast
[09:53] DocuSign's French acquisition: Navigating labor law and Ministry of Finance approvals
[12:16] Execution velocity: Getting shit done fast as a competitive advantage
[15:43] Personal secret sauce: Learning fast, working with smarter people, execution focus
[18:58] PR per engineer per week: The "less bad" velocity metric
[22:26] Vertical team alignment and minimizing cross-team dependencies
[24:22] Monorepo philosophy: Resist microservices until it's genuinely painful
[27:02] Framework skepticism: Why Spotify and GitLab models are "mostly marketing"
[30:41] Quarterly focus: Solve one major problem every three months
[32:30] Guild structure: Formalizing existing technical conversations
[36:14] Platform teams + vertical feature teams = ownership without dependencies
[38:31] The Linear of email: Laser-focused personas and design-centric approach
[40:25] Four hours per week saved: The value proposition for heavy email users
[42:05] 100-millisecond rule: Offline-first architecture for instant interactions
[46:16] Google's engineer-driven culture and the Gmail maintenance problem
[48:38] Promotion frameworks determine product quality
[50:02] Career advice: Take more risk in Europe - safety nets enable experimentation