since-until

Honest, calendar-aware date differences with user-defined named anchors. One engine, three front doors.

cargo install since-until

…installs three binaries that all share one engine and one anchors file:

binary	what it is
since	CLI, past-leaning — "6 years, 2 months, 30 days ago"
until	CLI, future-leaning — "in 6 months, 24 days" (gentle note if past)
since-until-mcp	MCP server (stdio) — since, until, list_anchors tools

zsh users: read this about until

until is a zsh reserved word (the until …; do …; done loop). zsh recognizes it at parse time, before any PATH lookup, so a bare until tomorrow never reaches the installed binary — instead you drop into an until> continuation prompt (and with a non-command argument it can loop forever). since is unaffected. This is a shell naming collision, not a bug — since-until installs the binary correctly at ~/.cargo/bin/until; the shell just intercepts the name first.

Two ways to run it with zero setup — both quote/escape past the reserved word:

command until tomorrow
\until tomorrow

For everyday use, add a short, safe wrapper to your ~/.zshrc (till is a natural synonym and is not reserved):

# since-until: `until` is a zsh reserved word; `till` calls the real binary.
till() { command until "$@"; }

Then till tomorrow, till 2030-01-01, till covid all work. The wrapper uses command until internally, so it can never recurse into the keyword. A ready-to-source version lives at contrib/until.zsh:

source /path/to/since-until/contrib/until.zsh

Note: aliasing the bare name (alias until=…) does not work — the reserved word still wins, and a looping alias body can hang the shell. Use command until, \until, or the till function. bash users are unaffected; until is reserved there too, but a bare until tomorrow simply errors rather than shadowing — still, the same wrappers work if you want them.

Why not just rename the binary? Keeping until preserves the since / until symmetry that's the whole point of the tool, and the binary itself is correct on every platform and shell that doesn't reserve the word. The collision is purely lexical, so the fix belongs in your shell config, not in the command's name.

The engine

A signed, calendar-honest difference between a target date and now, broken into years / months / days plus a direction (past / future / today) and a humanized sentence. Month-ends and leap years are handled the dateutil way — step back whole months without overshooting, then measure the leftover days — so Jan 31 → Mar 1 is "1 month, 1 day", not a day-borrow underflow.

Tokens & anchors

Every command takes a token: either an ISO date (YYYY-MM-DD) or an anchor nickname. Resolution order is ISO-parse first, then nickname lookup, then a clear error — so a literal date can never be shadowed by an anchor.

since 2020-03-01            # 6 years, 2 months, 30 days ago
since anchor add covid 2020-03-01
since covid                 # covid (2020-03-01): 6 years, 2 months, 30 days ago
until covid                 # ... ago  (heads up — that date has already passed)
since anchor list
since anchor remove covid

Anchors are a flat nickname -> ISO date JSON map at the platform config dir (e.g. ~/.config/since-until/anchors.json), hand-editable, case-insensitive, shared by all three binaries. A missing file is simply an empty set.

MCP

since-until-mcp speaks MCP over stdio (built on rmcp). Tools return structured output — the numbers and the sentence:

{ "token": "covid", "date": "2020-03-01", "years": 6, "months": 2, "days": 30,
  "direction": "past", "humanized": "6 years, 2 months, 30 days ago" }

list_anchors returns the same nickname map the CLIs manage, so anchors added on the command line are immediately visible to the model.

License

MIT