When Words

when-words

Human-friendly date and time formatting as pure functions. Converts timestamps to relative phrases ("3 hours ago"), duration strings ("2 hours, 30 minutes"), parses duration input ("2h30m" to seconds), generates contextual date labels ("Yesterday"), and formats smart date ranges ("January 15 -- February 15, 2024").

Design principles

• Pure functions only — every function takes explicit timestamps or values; no function ever accesses the system clock.
• UTC throughout — all calendar math uses UTC. No timezone handling.
• No inter-node dependencies — each node is a standalone leaf function.
• Clarity over performance — reference code prioritizes readability.

Node graph

All 5 nodes are leaf nodes with no inter-node dependencies:

time-ago          (standalone)
duration          (standalone)
parse-duration    (standalone)
human-date        (standalone)
date-range        (standalone)

Node table

Total: 5 nodes, ~108 tests, 100% line and function coverage.

Subset extraction

Every node is independent — any single node or combination works alone without pulling in other nodes. Common subsets:

• time-ago only — relative timestamps for feeds, notifications
• duration + parse-duration — bidirectional duration formatting
• human-date + date-range — calendar/scheduling UI labels
• all — full library

Input format

The skill accepts $ARGUMENTS in this format:

<nodes> [--lang <language>]

• <nodes> — Space-separated node names, or all for the complete library. Valid names: time-ago, duration, parse-duration, human-date, date-range.
• --lang <language> — Target language (default: typescript). Supported: python, rust, go, typescript.

Examples:

• time-ago --lang python
• duration parse-duration --lang rust
• all --lang go

Translation workflow

1. Read this file for overview and node selection
2. Read nodes/<name>/spec.md for behavioral spec and test vectors
3. Read nodes/<name>/to-<lang>.md for language-specific translation hints
4. Consult reference/src/<name>.ts only if the spec is ambiguous

Generated Code Documentation

Every public function, class, type, and interface in generated code must have idiomatic doc comments in the target language's standard format:

Doc comments should describe what the function does, its parameters, return value, and error conditions. Derive content from the node spec — do not invent behavior not in the spec.

Each generated file must include a provenance header as the first comment, in the file's idiomatic comment style:

Generated by {agent} using {model}
From special:when-words (https://github.com/caryden/special)
Node: {node-name}

Replace {agent}, {model}, and {node-name} with actual values. The provenance trace makes generated code traceable back to the skill and model that produced it.

Error handling

• duration throws on negative input
• parseDuration throws on: empty string, unrecognized input, negative values, bare numbers without units, unrecognized unit names
• timeAgo, humanDate, dateRange are total functions (no error cases)
• dateRange auto-swaps if start > end

Reference info

• Language: TypeScript (Bun runtime)
• Coverage: 100% line and function coverage
• Test runner: bun test
• No external dependencies

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