October 23, 2026 · AI 101
AI 101: What Is a .env File?
A .env file is a small hidden text file on your computer that holds your passwords and keys. Claude Code only ever needs each one's name. The real value stays in the file.
NameLin, Michelle, MD
ServiceEmergency Medicine
FacilityUCSF · San Francisco General
AllergiesBureaucracy
Michelle Lin, MD
Professor of Emergency Medicine at UCSF · founder of ALiEM · AI tinkererdirects AI systems(the words "AI tinkerer" are crossed out in red pen and corrected to "directs AI systems")
the old site really did call me a "tinkerer." corrected, June 2026.
I spent 25 years becoming a professor of emergency medicine. Then I learned to build. I don't write code. I direct it, the way an attending directs a resuscitation: clear intent, constant verification, no pretending to know things I don't. These days I'm building AI systems for academic clinicians and writing down what I learn, mistakes included.
Get in touchMessages come straight to my inbox, not an intake form.
Flowsheet· career vitals · checked October 2026
25 yrs
UCSF faculty · Professor since 2015
2M
readers a year at ALiEM
67
peer-reviewed papers
0
lines of code written
still true. I checked.Now
Interval note · October 2026Active problems
- Writing the AI Learning Journal. Latest entry: AI 101: What Is a .env File?.
- Running two systems in daily use: PAIA, my AI chief of staff, and a promotion-letter drafting workflow the UCSF EM promotion committee uses.
- Studying paramedic radio calls, poison center calls, and SF EMS records with AI, in three IRB-approved QI studies.
The AI Learning Journal
Progress notes- October 23, 2026AI 101
AI 101: Claude Code Leaked My WordPress App Password
Claude Code printed my WordPress app password in our chat while fixing an upload error. Why that counts as a leak, why changing your WordPress password doesn't stop it, and what to do instead.
- October 23, 2026AI 101
AI 101: What Is an App Password?
An app password is a second password to your WordPress account that lets a tool like Claude Code work as you. What it is, why it's worth having, and how to make one.
- January 16, 2026AI Builder
Google Analytics Isn't the Only Option
I fought GA4 for years before discovering there's another way. The real lesson isn't about analytics—it's about questioning defaults.
- January 15, 2026AI Builder
Memory is the Missing Thread
I spent years building one-off tools that unraveled quickly. I then discovered the thread that could stitch them all together - me and my memories.
- December 27, 2025AI Builder
How I Stopped Being Afraid of Claude Code
The terminal was too intimidating. Then I hit a wall with copy-pasting, asked Claude for help, and discovered a workflow I didn't know I needed.
The Builds
Medication list · reconciled October 2026Two systems in daily use, three IRB-approved studies in progress.
| System | Status | What it is |
|---|---|---|
| Faculty Promotion Letter Automation | In daily use | n8n workflow that curates faculty documents and generates first-draft promotion letters with transparent audit trails and flags for human review. Currently in use by UCSF EM promotion committee. |
| PAIA: Executive AI Assistant | In daily use | Personal AI assistant built with Claude's Agent SDK featuring memory, journaling, board of directors advisory sessions, CRM, YouTube video analyzer, and growing skill library. |
| Base Hospital Radio Call Analysis | IRB-approved QI · in progress | AI-powered transcription and QI analysis of base hospital radio calls between paramedics and physicians. |
| California Poison Center Call Analysis | IRB-approved QI · in progress | Using AI to transcribe and analyze poison center calls for quality improvement insights. |
| SF EMS Medical Record QI Analysis | IRB-approved QI · in progress | AI-driven quality improvement analysis of San Francisco EMS Agency patient care records. |
The Record
Past history · 1993 → present- UCSF / Zuckerberg San Francisco General
- Professor of Emergency Medicine (faculty 2001–, Professor 2015–). Practicing at ZSFG; Director of the Digital Innovation Lab.
- ALiEM — Academic Life in Emergency Medicine
- Founder & Editor-in-Chief, 2008–. Grew a solo blog into one of the world's most-visited med-ed sites, 2M+ annual views.
- ALiEMU
- Co-created free learning management system, 2014–. 75,000+ course completions.
- #PostitPearls
- Hand-drawn post-it teaching doodles from the ED, 2017–.
- Publications
- 67 peer-reviewed papers across Digital Scholarship & Social Media (28), Medical Education Scholarship (15), ALiEM AIR Series (9), Wellness & Burnout (6), Virtual Communities & Mentorship (5), COVID-19 & Virtual Education (4).
- Education & training
- Stanford BS (Biology) and Stanford MD; emergency medicine residency at Harbor-UCLA.
- Elsewhere
- EM editor at DynaMed. Dissemination lead, PECARN SPARC node. "The Lin Sessions" on EM:RAP.
Tricks of
the Trade
the Trade
Tricks of the Trade in Emergency Medicine - 50 clinical tricks from 38 experts, 100+ photos, expert authors, real-world tips. Buy a copy or read about it.
Signed and dated · October 2026