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Documents the Stack 0.2.0-dev.20260702.2 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.

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What works signed out

stack
stack doctor
stack demo
Signed out local use includes:
SurfaceSigned-out behavior
CockpitAgent pane, sessions, local threads, and local receipts
WorkerCodex/BYOK by default
Goal modeSidecar events, monitor status, and /goal
Local researchLocal GEPA when synth-optimizers is installed
stackdLocal 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.

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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

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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.

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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.