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Documents Stack 0.2.0-dev.20260703.2 local-first, hosted-connect, and nightly install behavior. See Stack Changelog for release state.
Stack runs locally without a Synth signup. This gets you from download to a working cockpit, then connects it to the Codex coding agent.

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Install

Nightly (macOS, Apple Silicon): 
curl -fsSL https://stack.usesynth.ai/install.sh | sh -s -- --channel nightly
Or download the tarball from the releases page and run the bundled installer. From source (requires Bun): 
git clone https://github.com/synth-laboratories/stack
cd stack && bun install
bun run src/main.ts

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The signed-out loop

No account required: 
stack            # launch the cockpit
stack demo       # run a local demo and write a receipt
stack doctor     # check your environment
stack update     # check for a newer nightly
stack demo writes a local, reproducible receipt — that is the whole first-win loop, offline. The local worker remains Codex/BYOK by default. Missing Synth auth should show a hosted-feature connect prompt, not a boot blocker. See Local-only mode.

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Configure with Codex

Stack drives a coding agent as its harness. The default harness is Codex: 
export STACK_HARNESS=codex
export STACK_CODEX_COMMAND=codex     # path to your codex binary, if not on PATH
stack
Stack ships Codex skills that teach the agent how to operate inside the cockpit — install them once:
  • stack-local-setup — local environment + first-run wiring
  • synth-via-stack — how to reach hosted Synth features from Stack
  • stack-agent-bridge — the typed stackd surfaces the agent uses
Run stack doctor to confirm the harness, Codex command, and stackd health are all green before starting a session.

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Connect hosted Synth when needed

Hosted SMR, Research Factories, hosted optimizers, remote sync, and Synth inference require a Synth key: 
stack auth open signin
stack auth verify --json
See Connect Synth and Hosted ops.

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Goal mode (sidecar monitor)

For long Codex runs, read Goal mode & monitor — Sidecar events (e), sidecar thread (t), and agent tape (a).

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Telemetry

Stack has two local telemetry tiers. Basic DAU is on by default and can be turned off. Advanced feature usage and session length stay off until you accept the prompt. Telemetry never includes your code, prompts, paths, commands, or secrets. 
stack telemetry digest     # see local counts and upload cursor state
In the TUI, use /settings telemetry to change choices.

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