Connect Synth

Sign in to unlock hosted SMR, Factories, hosted optimizers, and Synth inference from Stack.

Documents the Stack 0.2.0-dev.20260702.3 hosted-connect surface. Synth sign-in is optional; local Stack continues to work without it.

Connect Stack when you want cloud-backed Synth features. The same environment selector in the cockpit can target dev, staging, or prod, and each environment uses its configured API base URL and auth variable.

Get a key

Create a key at usesynth.ai/keys, then export it in your shell or configure an authEnvFile.

export SYNTH_API_KEY="sk_..."
stack doctor

For staging, use the environment variable configured in your stack.config.json for staging, usually SYNTH_STAGING_API_KEY.

Auth commands

stack auth urls --json
stack auth open signup
stack auth open signin
stack auth open keys
stack auth verify --json

The browser URLs carry Stack attribution for product activation. They do not paste credentials into Stack prompts or logs.

What unlocks

Feature	What changes after connect
Hosted SMR	List runs, inspect questions/approvals, message runs, preview outputs
Factories	List Factories, inspect linked projects/runs, wake or pause/resume with confirmation
Hosted optimizers	List jobs, preview/download artifacts, cancel jobs
Remote sync	Record push/pull receipts and remote gardener narration
Synth inference	Read catalog/usage and use opt-in aux or billed GLM profiles

If auth is missing or rejected, hosted surfaces show a point-of-need connect prompt. Local work remains available.

Keep keys out of prompts

Use environment variables or authEnvFile; do not paste raw keys into prompts, tickets, screenshots, or logs.

Next: Hosted ops and Hosted inference.