~/.cues/IDENTITY.md is where your personal details live: a YAML frontmatter file whose fields power my email _ and personalised drafting. Its defining property is how the values reach the model: in the default mode, they don't.
Keys become tokens
Each frontmatter key derives a token by name: firstName: Wilfred becomes [FIRST NAME], email: becomes [EMAIL], workCity: becomes [WORK CITY]. The fluid-blank and transform-blank pipelines can then resolve those tokens in _ lookups and rewrites: draft an email to my landlord _ comes back signed with your actual name.
Safe mode is the default
The identity-context-mode scalar has three values: off, safe (default), and raw. In safe mode the LLM is shown only a catalog of token names and descriptions; it answers using tokens, and a post-processor on your machine substitutes the real values after the response arrives. Safe mode is bidirectional: if you type a stored value into the buffer yourself, it is dehydrated to its token before any LLM-bound text is dispatched, and the response is hydrated back locally. Your personal data never reaches the provider's logs by construction, from either direction. Raw mode (which inlines values for better prose register) exists but is deliberately opt-in and hidden from the settings menu.
Writing to it
Manage it with opencues identity: an interactive interview, plus scriptable set / remove / list --json. Every write path goes through a mandatory validator: key-shape checks, value caps, token-collision rejection, and a 64-field capacity ceiling, so malformed entries are refused at write time. You can also edit the file directly; it's yours. Some blanks bind to specific fields too: the weather blank can use your stored workCity as its ambient default, so do i need a jacket _ works without naming a city.
Uninstalling OpenCues leaves the file alone (it's user config, like the rest of ~/.cues/), and the whole feature switches off with one scalar if you'd rather not use it.
Related: Identity context · opencues identity · Security model · The sentinel blank · GitHub repo