Local-only mode

Run Stack locally without a Synth signup, then connect only when you want hosted features.

Documents the Stack 0.2.0-dev.20260702.3 local-only contract. See Stack Changelog for the current release state.

Stack is local-first. You can install, launch, run a Codex worker, use goal mode, inspect local threads, and run local optimizer workflows without a Synth account or SYNTH_API_KEY.

What works signed out

stack
stack doctor
stack demo

Signed out local use includes:

Surface	Signed-out behavior
Cockpit	Agent pane, sessions, local threads, and local receipts
Worker	Codex/BYOK by default
Goal mode	Sidecar events, monitor status, and /goal
Local research	Local GEPA when synth-optimizers is installed
stackd	Local state, thread events, exports, telemetry choices

Hosted panels may show connect prompts while signed out. Those prompts are not a boot gate and do not disable local work.

Verify the contract

Run:

env -u SYNTH_API_KEY -u SYNTH_STAGING_API_KEY stack doctor --json

Look for:

local_ready=true
synth_sign_in_optional=true
worker=codex_byok
synth_worker=explicit_profile_only

Telemetry

Stack telemetry uses a pseudonymous local install id. Basic DAU can be turned off; advanced product telemetry stays off until you approve it in the TUI. Telemetry does not include code, prompts, paths, commands, or secrets.

stack telemetry digest

Use /settings telemetry in the cockpit to change choices.

When to connect

Connect only when you want hosted Synth features:

• hosted SMR runs and run messages;
• Research Factories and Factory levers;
• hosted optimizer jobs and artifacts;
• Synth inference catalog, usage, and billed GLM;
• remote sync receipts and remote gardener narration for cloud work.

Next: Connect Synth.