Background multi-cursor browser and macOS computer-use engine across unfocused Chrome tabs and native apps.
LIFAN CHEN · INDIE BUILDER & STAFF ENGINEER @ GOOGLE
Local tools, frontier ML, and AI agents—verified by evals.
01 · LOCAL Faster Mac Use · Agent Autofill · QuotaSwitch · Perks Reminder · Foliofen CLI
Interactive build inspector for Faster Mac Use, Agent Autofill, QuotaSwitch, FreshPowder, Perks Reminder, and AI Builder Brief. Full details follow in Selected Builds below.
Selected Builds
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Local-first personal vault and MCP broker for macOS agents with scoped credentials and explicit approval gates.
Unified multi-account switcher and 30s background quota auto-rotator for Antigravity and OpenAI Codex.
Ski and snowboard deal aggregator across 28 North American shops, filtered by size and budget.
Open-source credit card benefits, welcome bonus, and annual-fee ROI tracker with zero bank logins.
Evidence-gated daily AI brief distilling noisy launches into source-linked Top 10 technical developments.
Weekly six-minute Chinese podcast synthesized from USCardForum threads with source receipts via RSS.
Local-first Chrome harness for exporting patient-owned Epic MyChart records into Markdown & JSONL with zero cloud custody.
Fail-closed Python framework for source-transparent podcast pipelines with StoryCluster gates, NotebookLM, and atomic R2 + RSS.
Open-Source CLI Tools & Agent Infrastructure
Foliofen CLI →
Local Chrome harness for patient-owned MyChart health record exports (Markdown & JSONL).
CastForge →
Source-transparent Python podcast framework with StoryCluster gates, NotebookLM, and atomic R2 + RSS.
QuotaSwitch →
Unified quota-driven multi-account switcher and auto-rotator for Antigravity and Codex.
Perks Reminder →
Local-first credit card benefits, welcome bonus, and annual-fee ROI tracker.
Context Harness ↗
Filesystem memory layer and companion skills for coding agents.
Writing, Quick Thoughts & Field Notes
Sharp builder takes (X, Reddit, RedNote), long-form essays, and 59+ daily AI Builder Briefs.
Flagship Essays & Build Logs
Deep Dives
Why I built a local personal vault for AI agents on my Mac ↗
Brokering scoped fields, Keychain logins, and 2FA codes without cloud bot vaults.
Why I built Foliofen CLI while the portal kept changing ↗Exporting patient-owned records locally without handing a third party permanent account custody.
Show HN: Foliofen CLI — Technical feedback & failure modes ↗Why local control is only a real feature when recovery paths and scope limits are explicit.
Building Perks Reminder: A free, open-source benefits tracker ↗Keeping reminders, exportable JSON, and correction paths local without bank logins.
Daily AI Builder Briefs
59+ EditionsDaily field notes on AI developments that change what builders make and evaluate, with primary receipts.
Quick Thoughts & Builder Takes (X · Reddit · RedNote 小红书)
All quick takes (EN / 中文) →
On reverse-engineered console games on iOS →
Great Agent porting benchmark, poor phone experience vs. native mobile hits like Balatro (EN / 中文).
Opus 5.5 cured my Vibe Coding burnout →
Why daily quota FOMO and fighting defensive GPT slop kills builder flow state (EN / 中文).
Why I avoid cloud bot password vaults →
Shared bot VM state, plaintext CSV imports, and why local Keychain + 1-time extension handles win.
Small context beats broad repo archaeology →
Paired eval across 32 repos: 9.1/10 vs 7.0/10 after replacing prompt walls with 4 compact files.
Building a local MyChart CLI in the NICU →
Keeping daily family lab records current on-device without uploading PHI to third-party clouds (EN / 中文).
About & Engineering Philosophy
How I design, verify, and ship local-first tools and agent harnesses.
I’m a Staff Engineer at Google building local-first software, agent systems, and the evaluation loops that make autonomous workflows trustworthy.
I focus on practical automation with clear boundaries: keep personal data on the user’s machine, measure every agent action with token and latency receipts, and require human approval before mutating external state.
The Evaluation Loop
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01 · Source — Anchor on primary artifacts
Start from raw commits, protocol traces, and DOM snapshots rather than secondary summaries so every claim is reproducible.
Applied in: AI Builder Brief & Foliofen CLI