BrightDate — Workspace

Named in homage to Star Trek's Stardate — one universal scalar to rule them all.

This workspace contains the BrightDate v1.0 libraries: a scientifically grounded, timezone-free decimal day representation anchored at J2000.0 via a TAI substrate.

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Crates

Crate	Path	Description
brightdate	brightdate/ (Rust)	Core BrightDate type, TAI conversions, leap second table
bdate	bdate/	Date formatting and calendar utilities
btime	btime/	Time-of-day utilities
buptime	buptime/	Process uptime tracking
bcal	bcal/	Calendar arithmetic
bwatch	bwatch/	Stopwatch / interval utilities

TypeScript library

Package	Path	Description
@brightchain/brightdate	brightdate/	TypeScript/JavaScript BrightDate library (npm)

Showcase

App	Path	Description
BrightDate Showcase	brightdate/showcase/	Vite+React live demo

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The BrightDate v1.0 Design

Epoch: J2000.0 — Astronomically Correct

J2000.0 is defined in Terrestrial Time (TT) as 2000-01-01T12:00:00 TT.

Timescale	Representation	Value
TT (definition)	2000-01-01T12:00:00.000 (no zone)	Unix s 946_728_000
TAI	2000-01-01T11:59:27.816 (no zone)	Unix s 946_727_967.816
UTC label	2000-01-01T11:58:55.816Z	Unix ms 946_727_935_816

BrightDate = 0 at 2000-01-01T11:58:55.816Z.

TAI Substrate

bd = (taiUnixSeconds − 946_727_967.816) / 86400

BrightDate ticks in exact SI seconds. Leap seconds exist only at UTC boundary conversions.

Key Constants

Constant	Value
J2000_UTC_UNIX_MS	946_727_935_816
J2000_TAI_UNIX_S	946_727_967.816
J2000_TT_UNIX_S	946_728_000
TAI_UTC_OFFSET_AT_J2000	32 s
TT_TAI_OFFSET_SECONDS	32.184 s
CURRENT_TAI_UTC_OFFSET	37 s (as of 2017)
GPS_EPOCH_UNIX_TAI	315_964_819

Reference Epochs

Event	UTC	BrightDate
J2000.0 anchor	2000-01-01T11:58:55.816Z	0.000000000
TT noon (definition)	2000-01-01T12:00:00.000Z	≈ 0.000742870
Y2K midnight	2000-01-01T00:00:00Z	≈ −0.499257130
Unix epoch	1970-01-01T00:00:00Z	≈ −10957.499512
GPS epoch	1980-01-06T00:00:00Z	≈ −7300.499408

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Companion Types

BrightDate ships in three flavors so you can pick the right trade-off between ergonomics and precision. All three anchor on the same J2000.0 / TAI substrate — they only differ in how the value is stored.

Type	Representation	Precision	Range	Use when…
BrightDate	f64 decimal days since J2000.0	~190 ns in the current era; widens with magnitude	±287,000 years from J2000	The 99% case — math, astronomy, scheduling, logging, display. Sorts, diffs, and serializes natively.
BrightInstant	i64 TAI seconds + u32 nanos since J2000.0	1 ns exactly, everywhere	Effectively unlimited	You need nanosecond precision at any magnitude — distributed systems, GPS engineering, interplanetary mission timing. The rigorous companion to BrightDate.
ExactBrightDate	i128 picoseconds since J2000.0 (Rust) / BigInt picoseconds (TypeScript)	1 ps exactly, everywhere	Effectively unlimited	You must round-trip arbitrary Unix milliseconds bit-for-bit — blockchain consensus, archival storage, byte-identical reconstruction.

Rust and TypeScript both ship all three companion types, plus the PBD / BrightLabel deep-time naming layer for pre-J2000.0 instants. You can convert freely between them: store in the exact form at storage boundaries, compute in BrightDate for speed and convenience.

use brightdate::{BrightDate, BrightInstant, ExactBrightDate, BrightLabel, brightdate_to_label};

let bd  = BrightDate::now();           // f64 ergonomic form
let inst = BrightInstant::from(bd);    // exact ns-precision form
let back: BrightDate = inst.into();    // round-trips for the f64 range

// Bit-exact Unix-ms storage:
let exact = ExactBrightDate::from_unix_ms(1_700_000_000_000);
assert_eq!(exact.to_unix_ms(), 1_700_000_000_000);

// Deep-time labelling: pre-J2000.0 instants page into PBD eras.
let pre = BrightDate::from_value(-1.0);  // one day before J2000.0
match brightdate_to_label(pre).unwrap() {
    BrightLabel::Pbd { era, .. } => assert_eq!(era, 1),
    _ => unreachable!(),
}

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Installing

From crates.io

The brightdate library and all five CLI tools are published on crates.io:

# Library (for use in Rust projects)
cargo add brightdate

# CLI tools
cargo install bdate     # date(1) replacement
cargo install btime     # time(1) replacement
cargo install buptime   # uptime(1) replacement
cargo install bcal      # cal(1) replacement
cargo install bwatch    # watch(1) replacement

From Homebrew (macOS / Linux)

The CLI tools are available via the Digital Defiance Homebrew tap:

brew tap digital-defiance/tap
brew install digital-defiance/tap/bdate
brew install digital-defiance/tap/btime
brew install digital-defiance/tap/buptime
brew install digital-defiance/tap/bcal
brew install digital-defiance/tap/bwatch

After tapping you can also use the short names: brew install bdate, etc.

Using the Rust library

# Cargo.toml
[dependencies]
brightdate = "0.1"

use brightdate::BrightDate;

let now = BrightDate::now();
println!("{:.5}", now);                  // e.g. 9603.57128
println!("{}", now.to_iso8601());        // 2026-05-11T12:34:56.789Z

See the crates.io docs for the full API.

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Building from source

Rust

cargo build --workspace
cargo test --workspace
cargo clippy --workspace -- -D warnings

TypeScript

cd brightdate
yarn install
yarn build
yarn test

Showcase

cd brightdate/showcase
yarn install
yarn dev

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License

MIT © Digital Defiance