ghstats/docs/design-guidelines.md

# Design Guidelines

Visual conventions for ghstats SVG cards. All cards share a single frame shape so they stack cleanly in a README — two cards sit side-by-side inside GitHub's ~816 px content column.

## Card frame

| Property | Value |
| --- | --- |
| Width × Height | **340 × 200** (matches github-profile-summary-cards) |
| Corner radius | 6 px |
| Stroke | `theme.Stroke` at `theme.StrokeOpacity` |
| Fill | `theme.Background` |
| Font family | `'Segoe UI', Ubuntu, Sans-Serif` |
| Title | weight 600, `theme.Title`, anchored at `(20, 30)`. Font size auto-shrinks from 15 px down to 11 px when the string wouldn't fit in `width − 20 − 4` at 0.6 × fontSize char-width (see `fitTitleFontSize` in `svg.go`). 40-char titles like `Commits by Weekday (last year, UTC+7.00)` land at 13 px. |

Generated by `header(width, height, bg, stroke, strokeOpacity, titleColor, title)` in `internal/card/svg.go`.

## Theme role mapping

| Theme field | Used for |
| --- | --- |
| `Title` | Card title text |
| `Text` | Primary content (values, names) |
| `Background` | Card fill + stroke around donut slices to separate colors |
| `Stroke` + `StrokeOpacity` | Card outline |
| `Muted` | Axis lines, axis labels, icons, legend metadata |
| `Accent` | Bars, area fills, stat values, fallback slice color |

Cards MUST NOT hardcode colors outside these fields. If a new visual needs a shade, pick the closest existing field — don't extend the schema without a strong reason.

## Row-based cards (profile, stats)

Single-column rows of `icon + label` or `icon + label + value`.

| Metric | Profile | Stats |
| --- | --- | --- |
| First row baseline (y) | 60 | 55 |
| Row spacing | 20 px | 20 px |
| Row x padding | 20 | 20 |
| Icon scale | `12/16 = 0.75` from 16×16 Octicon viewBox | same |
| Icon color | `theme.Muted` | same |
| Value font | 12 px, `theme.Text` | 12 px, weight 600, `theme.Accent`, right-anchored at `x = 320` |

Cap rows at what fits: up to 7 rows per card. Stats splits commits into lifetime + last-year rows.

## Donut cards (language breakdowns)

| Metric | Value |
| --- | --- |
| Donut centre | `(250, 110)` |
| Outer radius | 55 |
| Inner radius | 30 |
| Top-N entries shown | 7 rows max, "Other" inclusive (6 named + "Other" when there's a tail, up to 7 named when there isn't) |
| Slice stroke | `theme.Background`, 1.5 px (gap between slices) |
| Legend origin | `(20, 55)` |
| Legend row height | 20 px |
| Swatch size | 10 × 10 |
| Legend font | 11 px |

Language colors come from linguist via GraphQL (`repo.languages.edges[].node.color`). Missing colors fall back to `theme.Accent`.

When there's **exactly one slice** (one language at 100%), the renderer emits two concentric `<circle>` elements instead of a pie arc, because SVG's `A` command from point P back to the same P draws nothing. Regression guarded by `TestDonutSingleSlice`.

## Bar-chart cards (productive time, productive weekday, contributions-by-year)

| Metric | Value |
| --- | --- |
| Chart area | `x ∈ [35, 325]`, `y ∈ [45, 155]` (110 tall) |
| Bars | `productive-time`: 24 bars, 1 px gap · `productive-weekday`: 7 bars, 6 px gap · `contributions-by-year`: N bars (1 per active year) |
| Bar fill | `theme.Accent` for the peak bar; `mixHex(Background, Accent, 0.55)` dim for the rest so the busiest period reads at a glance |
| Y-axis ticks | `niceTicks(max, 5)` — 1/2/5 × 10^k ladder. `last = ceil(max/step) × step` so `yMax ≥ dataMax` always (bars can't poke above chartH into the title) |
| Axis caption | "hour of day" bottom-center on productive-time; weekday / by-year omit the caption since the x labels are self-describing |
| Title format | `Commits by Hour (<window>, UTC±N.NN)` / `Commits by Weekday (<window>, UTC±N.NN)` / `Contributions by Year` |
| Hover | `<title>HH:00 — N commits</title>` / `<title>Mon — N commits</title>` / `<title>YYYY — N commits</title>` |

## Heatmap card (contributions-heatmap)

| Metric | Value |
| --- | --- |
| Layout | **Two stacked halves** of ~27 weeks each. One-row 53-week layout forces cells down to 4 × 4 to fit in 340 px; splitting in half lets each half be 27 weeks wide at **8 × 8 square cells** — 4× the cell area. Year still reads top-to-bottom, left-to-right. |
| Cell size | 8 × 8 px square, 1 px gap |
| Grid geometry | `leftPad 30`, `topPadA 45` (top half), `halfGap 13`, `topPadB 120`. Each half is 7 × 9 − 1 = 62 px tall. Grid bottom at y=182 leaves 18 px for the frame border. |
| Cell colour | 5-bucket ramp `mixHex(Background, Accent, k/4)` for `k ∈ 0..4` — no dedicated ramp field on the theme schema |
| Weekday labels | Mon / Wed / Fri only, right-anchored in the `leftPad` gutter |
| Month labels | Printed above the first week where a 1st-of-month day falls; skipped when `x > width − 20` so `Dec` / `Apr` can't spill past the frame |
| Legend | "Less ▢▢▢▢▢ More" bottom-right |
| Hover | `<title>YYYY-MM-DD — N</title>` per cell |

## Stat-column cards (streak)

Three big-number columns (`340 / 3 ≈ 113 px` each) sharing one layout:

| Metric | Value |
| --- | --- |
| Column centres | 56, 169, 282 |
| Big number | 28 px weight 700, `theme.Accent`, `text-anchor="middle"` at y=95. Always a single `formatInt` integer so the column can't overflow |
| Label | 12 px, `theme.Text`, middle-anchored at y=120 |
| Detail line | 10 px, `theme.Muted`, middle-anchored at y=140 — streak date range (`Jan 2 — Dec 31` same year, `2024 — 2026` across years) or `of N total (P%)` for active days |

## List cards (top-starred-repos)

Rows of `language swatch + repo name + proportional bar + star count`:

| Metric | Value |
| --- | --- |
| Row spacing | 22 px, first row y=60 |
| Name | 12 px, `theme.Text`, `truncate(..., 17)` so a 40-char repo name doesn't overflow |
| Bar | `x ∈ [150, 270]` (120 px wide), 10 px tall, `theme.Accent` foreground over 15 % ghost track |
| Star count | 12 px weight 600, right-anchored at x=334, suffix `★` — no separate icon (the title `Top Starred Repos` already establishes context) |

## Area-chart cards (contributions)

| Metric | Value |
| --- | --- |
| Chart area | `x ∈ [28, 312]`, `y ∈ [45, 150]` (105 tall) |
| Curve | Catmull-Rom → cubic Bezier (tension 0.5) |
| Fill | `theme.Accent` at 25% opacity |
| Stroke | `theme.Accent`, 2 px |
| Y-axis | **Both sides**, mirrored, same tick values |
| X-axis labels | `mm/yy`, stride-thinned to ~6 labels regardless of bucket count |
| Axis caption | "mm/yy" bottom-center |
| First/last labels | Always printed (pinned endpoints) |

Missing months in the `[first, last]` range are inserted as zero-count rows to keep the curve time-continuous.

## Icons

- Sourced from [Primer Octicons](https://primer.style/octicons/) 16×16 set.
- Stored as raw `<path d="…"/>` strings in `internal/card/icons.go`.
- Rendered inside `<g transform="translate(x,y) scale(0.75)" fill="muted">…</g>` (scaled to fit the 12 px box).
- Used: `iconRepos`, `iconCompany`, `iconLocation`, `iconClock`, `iconLink`, `iconPeople`, `iconStar`, `iconCommit`, `iconPR`, `iconIssue`, `iconReview`.

Add new icons by copying the `<path>` from Octicons and appending to `icons.go`. Keep them to the same 16×16 viewBox so the existing scale math applies.

## Fit-the-frame invariant (MUST hold before release)

Every card MUST render entirely inside the 340 × 200 frame **for every profile the card can encounter**, not just the author's. That means:

| Thing that varies | Worst case to design for |
| --- | --- |
| Star counts, commit counts, streak lengths, active days | 10-digit formatted integer (e.g. `1,234,567,890`) |
| Repo / language / company / location names | 40+ char strings with CJK / emoji |
| Number of active years | 20+ years (contribution history can start in 2008) |
| Contribution calendar weeks | 53 — not 52 — when the window spans a year transition |

Concrete rules this implies:

- **Reserve columns.** When a card has `N` equal-width columns, treat `340 / N` as the hard limit for each column's widest element. No centered text can be wider than its column.
- **Right-anchored values** (stats rows, top-starred bars) must leave a safety margin. Right edge ≤ `width − 6`; do not place an icon to the right of a right-anchored number (they collide on multi-digit values).
- **Long strings get truncated, not wrapped.** Use the rune-aware `truncate()` helper in `svg.go` — it's how `profile-details`, `top-starred-repos`, and `cardTitle` clamp to their column budgets. Never let a wide string push a later element off-screen.
- **Variable-count grids** (heatmap 7×N, by-year N bars) must compute cell size from the container width, not the other way round. Don't hardcode a cell size that only works for the author's profile.
- **Month / year tick labels** within `~20 px` of the right edge must be skipped (they read past the frame otherwise).

### Review checklist (before merging any card change)

Render the **dracula** theme against at least three profiles or synthetic fixtures:

1. **Tiny**: a brand-new account with 0 commits, 0 stars, 1 repo.
2. **Typical**: the author's profile (`tiennm99` via `demo/` regeneration).
3. **Adversarial**: seven-digit commit counts, 40-char repo / company / location names, 20 active years, 53-week span. A small synthetic `*.json` fixture is fine; it doesn't need a token.

Then open every affected SVG at 1× and 2× zoom and verify:

- [ ] No `<text>`, `<rect>`, `<circle>`, `<line>`, or path coordinate exceeds `x=340` or `y=200`, or falls below `x=0` / `y=0`.
- [ ] No two elements overlap in a way that makes either unreadable.
- [ ] Right-anchored numbers don't collide with icons, swatches, or bars.
- [ ] Peak-vs-dim highlighting still reads at a glance (dracula `Background → Accent` contrast is fine; light themes like `github` or `nord_bright` need a separate check).

The `demo/<theme>/` gallery auto-regenerates on every push to `main`; use the last CI run as the dracula reference, and stress-test the adversarial case locally before pushing.

## Accessibility

- Contrast is the theme author's responsibility — we don't validate at runtime.
- Tooltips (`<title>`) on productive-time bars let screen readers announce counts.
- No motion, no `<animate>` elements — profile READMEs render statically.

## Text overflow

- Long strings (bio, repo names, company, location, website) are **rune-truncated** by `truncate(s, n)` in `svg.go` (appends `…` after `n-1` runes). Profile rows clamp at 40, profile title at 34, top-starred repo names at 17.
- Y-axis tick labels are routed through `formatTick`, which abbreviates ≥ 1000 to `k` / `M` / `B` so no label exceeds 4 chars (`1500 → "1.5k"`, `12345 → "12k"`, `1234567 → "1.2M"`). Keeps the left gutter ≤ 28 px even for busy profiles.
- If a card still looks crowded at 340 px width, that's a card design problem — fix the layout, not silently drop data.