Four Pillars of Destiny (사주팔자) for macOS — computed precisely, interpreted entirely on your Mac.
English | 한국어
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four-eight reads a Four Pillars chart the way a careful practitioner would: it resolves the exact instant of the governing solar term, corrects for the longitude of the birthplace and for Korea's historical time zones, and only then names the sixty-cycle stems and branches. The chart is computed by a deterministic Swift engine. A local language model — if you choose to install one — is given those results and asked to do one thing: turn them into readable Korean prose.
The model never calculates. Every pillar, ten-god, and luck cycle comes from SajuKit, and every sentence in the interpretation carries a visible chip naming the rule it came from. Click the chip and you see the source text.
- Correct on the hard cases. Solar-term boundaries to the minute, Korea's UTC+8:30 eras, the 1948–1960 and 1987–1988 daylight-saving periods, and the 23:00 hour dispute — all handled explicitly, all covered by tests against published almanacs.
- Nothing leaves your Mac by default. Birth data is never transmitted; the network is used to download a model file, if you want one, and to check for updates. Since 0.3.0 you may point the app at an OpenAI-compatible provider of your choosing — and if you do, it shows you the exact text that will be sent, before the first send. The person's name and the raw birth timestamp are never sent even then.
- Schools disagree, so the app says so. True solar time, the 야자시 policy, and luck-cycle rounding are settings, not silent assumptions.
A birth of 1988-09-05 00:50 in Seoul. Three corrections stack up before a single pillar is named — and each one changes the answer.
입력 1988-09-05 00:50 서울
KDT (UTC+10) → 표준시 23:50, 전날
경도 126.978°E −32분 → 진태양시 23:18
23시대 + 야자시 정책 → 일주는 9월 4일 유지, 시두만 익일 기준
명식 時 日 月 年
壬 壬 庚 戊
子 戌 申 辰
Drop any one of those corrections and you get a different chart. This case is in the test suite as PublishedCaseTests.case1988Sept, matched against a published almanac.
| Chart | Calendar |
|---|---|
 |
 |
- Two ways in — read the chart once, or check what today carries. Both are the same engine.
- Deterministic engine —
SajuKitis a standalone Swift package with no runtime dependencies. - Optional on-device AI — Gemma 4 E2B or E4B via MLX, downloaded on demand. Stop and resume generation at any point; finished sections are never rewritten.
- Evidence-linked interpretation — every section shows which rules produced it, in the chart and in the calendar.
- Grounded consultation — write down what is on your mind and the app picks the myeongni axis, then answers from that axis's rules only. The axis and the evidence are visible before the answer arrives, and every answer carries the rules it actually used. The model is told to say it doesn't know rather than invent.
- It reads like a chat — ↩ sends, ⇧↩ inserts a newline. Past consultations are searchable and grouped by day, and when an answer finishes the app suggests what else this evidence can answer. Suggestions fill the composer; they never send.
- Lunar calendar — Korean 음양력 conversion including leap months, computed from first principles.
The calendar never labels a day good or bad. It marks days that contact your chart — a clash, a trine completion, a stem combination — and describes what kind of energy the day carries. Ranking days is fear marketing, and it contradicts the point of showing your evidence.
| macOS | 15.0 or later |
| Chip | Apple Silicon (M1 or later). Intel Macs are not supported — MLX is Metal-based |
| Disk | ~3.6 GB for Gemma 4 E2B, ~5.2 GB for E4B — optional |
| Build | Xcode 26.2+, XcodeGen |
The app is fully functional without any model: the rule engine composes the interpretation directly.
brew install --cask waylake/tap/four-eightNothing else to do. This path never shows the warning below.
Grab FourEight.zip from the latest release, unzip it, and move FourEight.app to /Applications.
Important
This app is not notarized by Apple. The Apple Developer Program costs $99/year and has no open-source exemption.
So the first launch shows "is damaged and can't be opened." The file is not actually damaged — that is what macOS says about apps it can't verify.
Fix it in Terminal (one line, reliable)
xattr -dr com.apple.quarantine /Applications/FourEight.appFix it in System Settings (no Terminal)
Control-clicking to open no longer works as of macOS 15. The order matters:
- Launch
FourEight.apponce. It will fail. That failure is what creates the button in step 3. - Open System Settings → Privacy & Security.
- Scroll down and click Open Anyway. This button is only visible for about an hour after step 1.
- Enter your login password.
Once is enough. Updates after that are handled by the app.
git clone https://github.com/waylake/four-eight.git
cd four-eight
xcodegen generate
open FourEight.xcodeprojSee HACKING.md for the command-line build and test workflow.
The app checks once a day and tells you when a new version exists. You see what changed and approve it before anything installs. This app does not rewrite itself behind your back.
Turn the check off in Settings → Updates if you prefer; the "Check now" button stays.
Releases that change how charts are computed say so in the release notes, because a chart you already read may come out differently.
The reading is always assembled from rule source text; AI prose is an optional layer on top. If you want that layer, there are three places it can come from.
| Where | Does your text leave this Mac? | What it needs |
|---|---|---|
| In this app (Gemma 4 / MLX) | No | 3.6 GB download, Apple Silicon |
On this Mac (Ollama, LM Studio, … on localhost) |
No — it is loopback | That server running locally |
| Off this Mac (any OpenAI-compatible provider) | Yes | Base URL, model name, API key |
No output token cap is sent by default. Reasoning models (DeepSeek, o-series, Gemini, …) spend that budget on thinking and the answer, so a low cap makes the model think itself out of room and return nothing while still billing you. The same model also varies up to 32× in output limit depending on which upstream route serves it, so there is no correct number for the app to pick. Set one in Settings if you want to bound cost.
Pick the third and the app shows you the literal text it is about to send, before it sends it. Not a checkbox — the actual bytes. It asks once per host: asking every time teaches people to click without reading, and at that point the gate is worse than no gate.
It does not ask for the second case. Loopback traffic never leaves the machine, so there is nothing to disclose, and warning there would drain the warning of meaning where it actually matters.
Plaintext http to anything off this Mac is refused, not warned about — your API key and whatever you wrote would ride in the clear.
There is no bundled provider list. Naming providers would imply endorsement the app cannot back up, since it has no way to verify how any of them handle what you send; base URLs and policies also change, so a bundled list rots silently. Check your provider's own policy for training use and retention.
The reasoning is in ADR 0011.
- Press ⌘N and enter a name, birth date, time, and birthplace.
- Watch the correction line under the preview — it shows the true solar time, the longitude offset, and whether daylight saving applied. If you disagree with a convention, change it in Settings.
- Read the chart in the centre column: four pillars, hidden stems, ten gods, twelve stages, five-element distribution, luck cycles.
- Read the interpretation on the right. Click any evidence chip to see the rule behind a passage.
- Optionally open Settings → Interpretation and choose where prose gets written: download Gemma 4 to run on this Mac, or point the app at an OpenAI-compatible provider you already use. Either way the same content is rewritten as flowing prose.
flowchart LR
A[Birth input] --> B[Time resolution]
B --> C[Pillars engine]
C --> D[Analysis]
D --> E[Fact tags]
E --> F[Rule index]
F --> G{AI enabled?}
G -->|no| H[Rule text]
G -->|yes| I[Gemma 4 via MLX]
H --> J[Interpretation + evidence]
I --> J
The interesting design choice is step E → F. Four Pillars has a closed ontology — ten stems, twelve branches, ten gods, five elements — so retrieval is a deterministic tag lookup, not vector similarity. The model receives a fixed set of facts and a fixed set of rule texts, and is instructed to combine them and nothing else. That is why a 2B-parameter model is sufficient, and why the interpretation cannot invent a pillar that isn't there.
Details: docs/architecture.md · docs/saju-engine.md · docs/on-device-ai.md
The engine is verified against published almanac data rather than against itself.
| Check | Coverage | Result |
|---|---|---|
| Solar term instants | 50 published times, 1954–2026 | within ±90 s |
| Published charts | 7 documented cases | exact match |
| Lunar conversion | round trip, every day of 2003 | consistent |
| Day pillar anchors | 1900-01-01 甲戌, 2000-01-01 戊午 | exact |
The published cases were chosen because they are hard: daylight saving overlapping a UTC+8:30 era, a birth two minutes after a solar term, midnight births that land on either side of the 야자시 boundary, and a birth in Washington D.C. Sources are listed in docs/research/manseryeok-validation.md.
Astronomy: VSOP87D truncated Earth series for apparent solar longitude, IAU 1980 nutation, Meeus chapter 49 for new moons, tabulated ΔT. No ephemeris files, no network, no AGPL dependency.
| # | Step | Status |
|---|---|---|
| 1 | Deterministic engine + golden tests | Done |
| 2 | Chart canvas, luck cycles, settings | Done |
| 3 | On-device interpretation with evidence chips | Done |
| 4 | Conversational follow-up questions | Done |
| 5 | Fortune calendar (annual, monthly, daily) | Planned |
| 6 | Compatibility between two charts | Planned |
| 7 | Print and PDF chart output | Planned |
Which conventions does the app use by default? True solar time from the birthplace longitude, no equation of time, 야자시 (the day pillar holds; only the hour stem advances), and luck-cycle rounding at 3 days per year. All four are configurable.
Why does my chart differ from another app? Almost always the 23:00 hour or the longitude correction. Compare the correction line under the chart header — it states exactly what was applied.
What if I don't know the birth time? The hour pillar is left empty and the chart is read as three pillars. Nothing is guessed.
Where is my data stored?
~/Library/Application Support/FourEight/people.json. Models go to the Hugging Face cache. Neither is transmitted.
Is this fortune telling? It is a faithful implementation of 자평명리 as a body of traditional thought. The interpretations are reference material, not medical, financial, or legal advice.
Issues and pull requests are welcome. See CONTRIBUTING.md for the process and HACKING.md for the development setup.
MIT — see LICENSE.
Gemma 4 models are distributed by Google under Apache 2.0 and are downloaded by the user at runtime; this repository contains no model weights. VSOP87 series data originates from the Bureau des Longitudes (Bretagnon & Francou, 1988).