Assay ships as a signed macOS collector. One binary. No Node. No source clone. Downloads are invite-only. You need a link of this shape: 
curl -fsSL https://download.assay.solutions/i/<invite>/install.sh | sh
The invite is in the URL. You do not paste a second secret. The installer picks the architecture, checks the download against published checksums, and puts assay on your PATH. It does not create a store. It does not start a timer. It does not touch your session logs. assay init is a separate, deliberate step. 
assay --version
This guide documents v0.48.0. If assay --version prints something else, treat that binary as the authority for flags.
The installer puts the binary in /usr/local/bin when it can write there, otherwise ~/.local/bin. Add that directory to PATH and reopen the shell.
The collector is Developer ID signed and notarized. A browser or AirDrop download is not blocked. First run may fetch the notarization ticket online.
The compiled collector is macOS today. A host that embeds Assay as a library needs Node ≥ 20 and the package. See Agent loop.

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Initialize

assay init            # ./assay.config.json in this folder
# or
assay init --global   # ~/.config/assay/config.json for the machine
init does four things:
  • Writes a config file, so later commands need no repeated flags.
  • Creates an empty store (schema applied). assay show works immediately and returns an empty rollup.
  • Creates the content key (~/.config/assay/transcript.key, mode 0600).
  • Prints next steps.
It is safe to run again. A second run reports what already exists. It never overwrites the key or the store. --force rewrites only the config file.
Back up the content key. Conversation text is sealed with it. Lose the key and the sealed text is unreadable. Counts, hashes, and labels survive. The words do not. Keep the key file in a password manager or a backup you already trust.

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What you have after init

PieceDefault
Config./assay.config.json or ~/.config/assay/config.json
Storea SQLite file named in the config
Content key~/.config/assay/transcript.key
Modecorpus
Capture rootsClaude Code, Grok, Codex, OpenCode session folders
No timer is installed yet. Capture and labelling stay off until you turn them on. See After install.

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Config resolution

Which file: --config-file → $ASSAY_CONFIG → ./assay.config.json → ~/.config/assay/config.json → none. Each value: flag > env > config file > built-in default. With no config file, behavior matches flag-only use. The config layer is additive. When you write a config for a newer Assay, upgrade the installed binary too. Check with assay --version. An unknown top-level section is a warning and is ignored. The section still does nothing until the build that understands it is installed. Pass --strict-config (or $ASSAY_STRICT_CONFIG=1) in CI, where a config naming a section the build cannot honour is the defect. Full file: Config.