decision-log — append a dated decision line

The engine is decision-log.js (portable Node, zero deps). It writes a single timestamped line per decision to a plain DECISIONS.md. This is deliberately NOT the append-only project record or a handoff snapshot — those belong to a project-memory system (see the companion claude-project-memory repo). It is the lightweight one-liner you jot when a call gets made; the line it prints to stdout is formatted to paste straight into a record entry later.

The timestamp always comes from the machine's real clock at runtime (new Date()) — never a caller-supplied date — and the zone is labelled from the ZONES map at the top of the script. It ships defaulted to a DST-aware US Central rule: UTC-6 → CST, UTC-5 → CDT, and any other offset prints as a literal UTC±H:MM. The file is append-only: existing lines are never rewritten, and a missing file is created with a one-line header.

Commands

node decision-log.js add "<decision>" [--why "<reason>"] [--file DECISIONS.md]
node decision-log.js list [--file DECISIONS.md]
node decision-log.js --canary

• add stamps the current clock and appends the line, printing it to stdout. Missing decision text exits 2. --why adds a (why: <reason>) clause. --file targets a different log (default ./DECISIONS.md).
• list prints every entry line (the - lines) in file order.

Examples

• Freeze call with a reason: node decision-log.js add "keep the factor weights frozen" --why "frozen regression must stay byte-exact" → - 2026-07-21 10:37 CDT - decided: keep the factor weights frozen (why: frozen regression must stay byte-exact)
• Log to another project's file: node decision-log.js add "guardian consent is the hard launch gate" --file ../other-project/DECISIONS.md
• Review what's been decided: node decision-log.js list

Copy the printed line into a project-memory record entry when you next append the record — that is the intended handoff between the two.

Setting your timezone

Zone labelling is one clearly-commented const at the top of decision-log.js:

const ZONES = { 360: "CST", 300: "CDT" };

The keys are getTimezoneOffset() minutes (minutes to ADD to local time to reach UTC, so a zone BEHIND UTC is POSITIVE): UTC-6 → 360, UTC-5 → 300. It defaults to US Central. Edit the map for your timezone — e.g. { 0: "UTC" }, or { 480: "PST", 420: "PDT" } for US Pacific. Any offset not listed falls back to a literal UTC±H:MM label, so the tool still works unedited anywhere.

Windows notes

• PowerShell 5.1: quote the decision and reason as whole double-quoted arguments: add "adopt GitHub Flow" --why "cleaner PR history". PS 5.1 has no &&/||/ternary, but this is a single command so that does not bite.
• Node writes the file as UTF-8 directly — do NOT pipe through Set-Content (it defaults to the ANSI codepage and would mangle a — or non-ASCII text).

Storage

A single append-only DECISIONS.md (default in the cwd; override with --file). One header line, then one - ... line per decision. Commit it if you want the decisions in version history.

Exit codes

0 ok · 1 canary failure · 2 usage error (missing decision text / unknown command / unwritable or invalid --file path).

Verification (the done-check)

node decision-log.js --canary

Self-tests both directions in a throwaway temp file: a valid add writes a well-formed line whose date equals the system date and whose zone label matches the current UTC offset (recomputed independently in the canary from the same ZONES map), --why appears only when given, a second add appends without disturbing the first line, and missing decision text exits 2 without creating a file. MUST print CANARY PASS n/n before you trust a result.

node decision-log.js --canary — MUST print CANARY PASS 29/29 before you trust a result.

ASCII-only markdown (rule added 2026-09-23)

Every .md file this skill creates or writes to gets ASCII characters only (bytes 0x00-0x7F) in the text you add. No exceptions for headings, tables, quotes, names or pasted tool output.

• Dashes: - (never an en or em dash). Arrows: -> and <-. Quotes: straight " and '. Ellipsis: .... Math: x, +/-, <=, >=, ~. Separators: -, ; or |. No emoji, no check-mark glyphs (use [x] and [ ]), no accented letters: transliterate names and quoted text.
• Check before saving. In a git repo, git diff -U0 -- <file> | grep -v '^+++' | grep '^+' | grep -nP '[^\x00-\x7F]' must print nothing. For a new or untracked file, grep -nP '[^\x00-\x7F]' <file> must print nothing.
• Leave non-ASCII in text you did not write. Earlier entries of an append-only record stay byte for byte; converting an existing file is a separate, explicit job.