HOW fAI WORKS
No magic. A watch process, plain files, and a loop you can inspect.
fAI runs alongside the tools you already use, captures as you work, and compounds what it learns into files you can read, diff, and roll back. Here's the whole mechanism.
synthesized · plain markdown
A GIT REPO YOU OWN · DIFF IT · BRANCH IT · ROLL IT BACK
history, not snapshots
THE MECHANISM
Capture. Seal. Synthesize. Inject.
Capture
A watch process polls your session transcripts as you work: every agent, Claude Code included. Nothing to configure.
Seal
On a cadence, captures move from your session journal into pending, then kept: branches on a git repo you own.
Synthesize
The model you choose distills what's kept into decisions, patterns, and context: the three FAI files.
Inject
Every run rewrites each agent's direction file (CLAUDE.md, AGENTS.md, .cursorrules and the rest), and MCP serves the vault live to tools that speak it.
deno run -A "https://www.fathym.com/fai/install.deno"Install in seconds, free, open source, runs locally.
HISTORY, NOT SNAPSHOTS
Your context is plain git.
Every session branches off, captures your work, and seals back. You can diff any two sessions, audit what changed, or roll anything back: the same moves you already trust for code, applied to your context.
Plain markdown. Git-backed. Yours forever.
WHAT THE FILES HOLD
Open the file your AI starts every session with.
$ cat FAI-PROJECT.md## Decisions- Postgres over MySQL: row-level security drove it (2026-06-14) → decisions/postgres-over-mysql.md- JWT for auth: sessions stay stateless → decisions/jwt-auth.md## Patterns- Repository pattern for data access → patterns/repository-data-access.md- Errors: typed results, never thrown strings → patterns/typed-errors.md
That's it: no hidden store, no black box. Your agent reads this on startup and works accordingly. And here's the test: delete your .fai folder. You'll feel the regression immediately, the AI suddenly asking things it already knew, forgetting preferences you'd stopped thinking about. That gap is what fAI is filling.
WHAT SYNTHESIS PRODUCES
Decisions, patterns, context, and shorthands you reuse.
Decisions
What you chose and why, so nothing gets relitigated next session.
Patterns
The approaches you repeat, distilled from what you actually did.
Context
The living picture of the project and how you work: the three FAI files.
Petnames
Reusable prompt shorthands: name a thing once, use it everywhere.
On the roadmap: crystallization goes further. Workflows you repeat become micro-agents: small, fast tools built from the way you already work. They run the routine jobs without a full model call, so you save the AI for the work that needs it.
SESSIONS
Named, resumable, never lost.
A session is organized around a piece of work, not the day you did it: name one auth and the decisions, patterns, and open threads you capture stay with it. When that work comes back around, weeks or months later, resurrect the session and everything from last time is intact.
$ fai$ fai --continue$ fai sessions list$ fai sessions <id> compound$ fai synthesize$ fai sessions list● auth active · last: 2h ago○ billing archived · 3 months ago$ fai sessions billing compound✓ context restored: picks up where you left off
SHARING
Share it the way you share code.
Your vault is a git repo like any other, so sharing works the way you already know: push it to a private remote you control (GitHub, your own server), and a teammate pulls it to bring your context into their setup. You choose what to share and when: nothing propagates automatically. When your team wants shared, living context with review built in, that's OpenX →
See it run on your own project.
deno run -A "https://www.fathym.com/fai/install.deno"