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+---
+name: gribouille
+description: >
+  Generate correct, idiomatic gribouille charts for Typst. Trigger on: "chart",
+  "plot", "scatter", "histogram", "bar chart", "boxplot", "heatmap", "time series",
+  or any request to visualise data in Typst using a Grammar of Graphics approach.
+version: 0.2.0
+min-binary-version: "4.0.0"
+allowed-tools:
+  - Read
+  - Write
+  - Edit
+  - Bash
+  - AskUserQuestion
+---
+
+# /gribouille
+
+Generate correct, idiomatic [gribouille](https://m.canouil.dev/gribouille) charts for Typst.
+Gribouille implements Wilkinson's Grammar of Graphics — the same mental model as ggplot2 and plotnine — compiled natively in Typst.
+
+```
+/gribouille scatter penguins flipper-len vs body-mass by species
+/gribouille bar chart of mpg highway economy by class, faceted by cyl
+/gribouille histogram of my-data.csv column "score"
+/gribouille compose two panels: weight vs mpg and horsepower vs mpg
+```
+
+---
+
+## Step 0 · Context detection
+
+Determine two things silently before asking anything.
+
+**A. Import mode:**
+
+| Signal | Import line |
+|---|---|
+| User mentions Typst Universe / `@preview` | `#import "@preview/gribouille:0.0.1": *` |
+| User has a local gribouille clone / `lib.typ` path | `#import "./path/to/lib.typ": *` |
+| Ambiguous | Ask: "Are you using gribouille from Typst Universe (`@preview`) or a local clone?" |
+
+**B. Embedding context:**
+
+| Signal | Action |
+|---|---|
+| User is inside a typst-author document | Generate only the `#plot(...)` block; add Step 9 handoff note |
+| User wants a standalone `.typ` file | Prepend `#set page(width: auto, height: auto, margin: 0.5cm)` |
+| Unclear | Default to standalone |
+
+---
+
+## Step 1 · Intent extraction (silent checklist)
+
+Before writing code, confirm these four dimensions. Ask only if 2+ are missing — one compact question at most, never a four-item form.
+
+| Dimension | What to extract | Example |
+|---|---|---|
+| **Chart type** | What visual form? | scatter, bar, histogram, boxplot, line, heatmap |
+| **Data** | Inline / built-in / external file? | `penguins`, a CSV path, or an array literal |
+| **Variables** | Which columns → which aesthetics? | x=flipper-len, y=body-mass, colour=species |
+| **Facets** | Split into panels? By what variable? | one panel per island |
+
+If chart type and data are both clear from context, skip the question entirely.
+
+---
+
+## Step 2 · Select chart type
+
+First-match table. Apply the first row that fits the user's description.
+
+| User says / data shape | Geom combination | Notes |
+|---|---|---|
+| "scatter", "relationship", two continuous vars | `geom-point(size: 2pt)` | Add `geom-smooth(method: "lm")` if trend desired |
+| "scatter + fit / regression / smoother" | `geom-point(size: 2pt, alpha: 0.65)` + `geom-smooth(method: "lm", se: true, alpha: 0.2)` | v1 supports `method: "lm"` only — not loess or glm |
+| "scatter + convex hull / group outlines" | above + `geom-mark(method: "hull", expand: 5pt, alpha: 0.25)` | |
+| "scatter + error bars" | `geom-point()` + `geom-errorbar(width: 0.3)` with `ymin`/`ymax` in mapping | |
+| "line chart / time series / trend over x" | `geom-line()` | Sort data by x first; use `geom-area()` if area-under-line matters |
+| "area chart" | `geom-area(alpha: 0.7)` | Requires ordered x |
+| "bar chart (counts)" | `geom-bar()` | Uses stat-count by default; map `x` only |
+| "bar chart (values / col chart)" | `geom-col()` | Data already has y values; map both `x` and `y` |
+| "stacked bar" | `geom-bar(position: "stack")` | Add `fill` aesthetic |
+| "dodged / grouped bar" | `geom-bar(position: "dodge")` | Add `fill` aesthetic |
+| "filled / proportional bar (100% stacked)" | `geom-bar(position: "fill")` | y becomes proportion 0–1 |
+| "histogram / distribution of continuous var" | `geom-histogram(bins: 12)` | Tune `bins` or use `binwidth` instead |
+| "overlapping distributions / frequency polygon" | `geom-freqpoly(bins: 12)` | Line version of histogram; good for comparing groups |
+| "boxplot / box-and-whisker" | `geom-boxplot()` | Add `geom-jitter(width: 0.2, alpha: 0.3)` for raw data overlay |
+| "heatmap / tile map" | `geom-tile()` | Requires x, y, fill aesthetics |
+| "2D histogram / bin2d" | `geom-bin-2d()` | Bins both x and y |
+| "hex bin (dense scatter)" | `geom-hex()` | Alternative to scatter for large datasets |
+| "contour lines" | `geom-contour()` | Requires x, y, z |
+| "filled contours" | `geom-contour-filled()` | Requires x, y, z, fill |
+| "error bars" | `geom-errorbar(width: 0.3)` with `ymin`/`ymax` in mapping | |
+| "horizontal error bars" | `geom-errorbarh(height: 0.3)` with `xmin`/`xmax` in mapping | |
+| "ribbon / confidence band" | `geom-ribbon(alpha: 0.2)` with `ymin`/`ymax` in mapping | Pair with `geom-line()` |
+| "rug plot (marginal ticks)" | `geom-rug(sides: "bl")` | Stack with another geom |
+| "path (connected in data order)" | `geom-path()` | Unlike `geom-line()`, does not sort by x |
+| "step function" | `geom-step(direction: "hv")` | Options: "hv", "vh", "mid" |
+| "segments / connectors" | `geom-segment(stroke: 1pt)` | `geom-curve()` for curved connectors |
+| "text labels on data points" | `geom-text(mapping: aes(label: "col"))` | Combine with `geom-point()` |
+| "labelled boxes (callouts)" | `geom-label(mapping: aes(label: "col"))` | Adds background box around text |
+| "dot plot" | `geom-dotplot()` | |
+| "Q-Q plot" | `geom-qq()` + `geom-qq-line()` | |
+| "quantile regression" | `geom-quantile()` | |
+| "spoke / wind vectors" | `geom-spoke()` | Requires x, y, angle, radius in mapping |
+| "count overplotting" | `geom-count()` | Size encodes count |
+| "function curve y=f(x)" | `geom-function(fun: x => calc.sin(x), n: 101)` | |
+| "horizontal reference line" | `geom-hline(yintercept: 0)` | |
+| "vertical reference line" | `geom-vline(xintercept: 0)` | |
+| "diagonal / slope reference" | `geom-abline(slope: 1, intercept: 0)` | |
+| "shaded rectangle region" | `geom-rect()` with `xmin`/`xmax`/`ymin`/`ymax` in mapping | |
+| "polygon" | `geom-polygon()` | |
+| "confidence ellipse" | `geom-ellipse()` | Or use `geom-mark(method: "ellipse")` |
+| "faceted" | Any geom above + `facet: facet-wrap("col")` or `facet: facet-grid(rows: "r", columns: "c")` | |
+
+Read `references/geom-table.md` for full parameter reference on any geom.
+
+---
+
+## Step 3 · Wire the data
+
+Choose the pattern that matches the data source.
+
+**Pattern A — Built-in dataset (no extra code needed):**
+```typst
+// penguins, mpg, and economics are exported by gribouille
+#plot(
+  data: penguins,   // or: mpg, economics
+  ...
+)
+```
+
+**Pattern B — Inline array literal:**
+```typst
+#let my-data = (
+  (x: 1.0, y: 2.1, group: "a"),
+  (x: 2.0, y: 3.0, group: "a"),
+  (x: 3.5, y: 1.8, group: "b"),
+)
+#plot(
+  data: my-data,
+  ...
+)
+```
+
+**Pattern C — External CSV (column headers become dictionary keys):**
+```typst
+#let raw = csv("data.csv", row-type: dictionary)
+// Numeric values arrive as strings from csv(); cast as needed:
+#let my-data = raw.map(r => (
+  x: float(r.x),
+  y: float(r.y),
+  group: r.group,
+))
+#plot(
+  data: my-data,
+  ...
+)
+```
+
+**Key rule — always quote column names in `aes()`:**
+```typst
+// CORRECT
+mapping: aes(x: "flipper-len", y: "body-mass")
+
+// WRONG — causes a compile error
+mapping: aes(x: flipper-len, y: body-mass)
+```
+
+---
+
+## Step 4 · Build the plot block
+
+Canonical skeleton. Include only the arguments that are actually needed — omit optional sections when defaults suffice.
+
+```typst
+#import "@preview/gribouille:0.0.1": *
+
+#set page(width: auto, height: auto, margin: 0.5cm)  // standalone only; remove in typst-author docs
+
+#plot(
+  data: <data>,
+  mapping: aes(
+    x: "<x-col>",
+    y: "<y-col>",
+    // add aesthetics as needed:
+    colour: "<group-col>",
+    fill: "<group-col>",
+    shape: "<group-col>",
+    size: "<numeric-col>",
+    alpha: "<numeric-col>",
+  ),
+  layers: (
+    geom-point(size: 2pt, alpha: 0.85),
+    // stack additional geoms here in draw order (bottom to top)
+  ),
+  // scales: only include when overriding defaults
+  scales: (
+    scale-y-continuous(labels: format-comma()),  // for large numbers (>9999)
+    // scale-x-log10(),
+    // scale-colour-viridis-d(),
+  ),
+  labs: labs(
+    title: "Chart Title",
+    subtitle: "Optional subtitle",
+    x: "X-Axis Label",
+    y: "Y-Axis Label",
+    colour: "Legend Title",
+    fill: "Legend Title",
+    caption: "Data source.",
+  ),
+  theme: theme-minimal(),  // alternatives: theme-classic(), theme-void()
+  width: 12cm,
+  height: 9cm,
+)
+```
+
+**Scale auto-selection — apply these rules silently before emitting code:**
+
+| Aesthetic + data type | Scale to emit |
+|---|---|
+| x/y continuous, values ≤9999 | Omit — default is fine |
+| x/y continuous, values >9999 | `scale-x/y-continuous(labels: format-comma())` |
+| x/y log scale requested | `scale-x/y-log10()` |
+| x/y date values | `scale-x/y-date(date-format: "[year]-[month repr:numerical]")` |
+| colour/fill discrete (categorical) | Omit — gribouille auto-trains; add `scale-colour-discrete(palette: ...)` only for custom colours |
+| colour/fill continuous | `scale-colour-continuous()` or `scale-colour-gradient(low: rgb(...), high: rgb(...))` |
+| colour viridis | `scale-colour-viridis-c()` (continuous) or `scale-colour-viridis-d()` (discrete) |
+| colour ColorBrewer | `scale-colour-brewer(palette: "Blues")` |
+| colour colourblind-safe | `scale-colour-okabe-ito()` |
+| alpha mapped to data | `scale-alpha-continuous(range: (0.1, 1))` |
+
+Read `references/scale-table.md` for full parameter reference.
+
+**Categorical column rule — use `as-factor()` when a column holds numeric-looking strings used for grouping:**
+```typst
+// cyl column contains "4", "6", "8" as strings
+mapping: aes(x: "displ", y: "hwy", colour: as-factor("cyl"))
+//                                               ↑ forces discrete treatment
+```
+
+**Typst markup in labs — use the `typst()` helper, not raw strings:**
+```typst
+labs(
+  title: typst("*Bold title* and #text(fill: blue)[blue text]"),
+)
+```
+
+**Theme customisation — verified parameter names from source:**
+```typst
+theme: theme-minimal(
+  text: element-text(family: "Source Sans Pro", size: 10pt),  // family:, NOT font:
+  plot-title: element-text(size: 14pt, weight: "bold"),
+  axis-text: element-text(size: 8pt),
+  axis-line: element-line(thickness: 0.5pt),  // thickness:, NOT linewidth:
+  tick-length: 0.08cm,
+  tick-labels: true,
+)
+```
+
+`element-text()` accepts: `size`, `weight`, `colour`, `angle`, `family`, `margin`
+`element-line()` accepts: `colour`, `thickness`
+`element-rect()` accepts: `fill`, `stroke`
+
+---
+
+## Step 5 · Faceting
+
+Add a `facet:` argument to split the chart into small multiples.
+
+**One variable → `facet-wrap`:**
+```typst
+facet: facet-wrap("island", ncolumn: 3),
+// Options: nrow:, ncolumn:, scales: "fixed"|"free"|"free_x"|"free_y"
+// labeller: label-value() (default) | label-both()
+// axes: "margins" (default) | "all_x" | "all_y" | "all"
+```
+
+**Two variables → `facet-grid`:**
+```typst
+facet: facet-grid(rows: "sex", columns: "island"),
+// v1 supports scales: "fixed" only
+// Either rows: or columns: may be omitted (but not both)
+```
+
+---
+
+## Step 6 · Multi-panel composition
+
+Use `compose()` when the user wants multiple **independent** plots arranged together. Use `facet-wrap/grid` when it's the same chart split by a grouping variable.
+
+```typst
+#let p1 = plot(
+  data: d,
+  mapping: aes(x: "wt", y: "mpg", colour: as-factor("cyl")),
+  layers: (geom-point(size: 2pt),),
+  width: 6cm, height: 4cm,
+  defer: true,  // REQUIRED for compose()
+)
+#let p2 = plot(
+  data: d,
+  mapping: aes(x: "hp", y: "mpg", colour: as-factor("cyl")),
+  layers: (geom-point(size: 2pt),),
+  width: 6cm, height: 4cm,
+  defer: true,
+)
+
+#compose(
+  p1, p2,
+  layout: "grid",            // "grid" or "stack"
+  columns: 2,
+  collect: auto,             // auto hoists shared legends; none = keep per-panel
+  guides-placement: "right", // "right" | "left" | "top" | "bottom"
+)
+```
+
+---
+
+## Step 7 · Guides / legend control
+
+```typst
+guides: guides(
+  colour: guide-legend(position: "bottom", direction: "horizontal"),
+  fill: guide-none(),
+  shape: guide-legend(nrow: 1),
+),
+```
+
+`guide-legend()` params: `title, nrow, ncolumn, reverse, position, direction, order, byrow`.
+`position` accepts: `"top"`, `"right"`, `"bottom"`, `"left"`, `"none"`, a Typst alignment like `top + right`, or a dict `(dx:, dy:)`.
+
+---
+
+## Step 8 · Accessibility
+
+Always emit an alt text string. Cache the plot in a `let` binding and call `get-alt-text()`:
+
+```typst
+#let p = plot(
+  data: penguins,
+  mapping: aes(x: "flipper-len", y: "body-mass", colour: "species"),
+  layers: (geom-point(size: 2pt),),
+  labs: labs(title: "Penguin Scatter", x: "Flipper Length (mm)", y: "Body Mass (g)"),
+  theme: theme-minimal(),
+  width: 12cm, height: 9cm,
+)
+
+#figure(
+  p,
+  caption: [Flipper length versus body mass for three penguin species.],
+  alt: get-alt-text(p),
+)
+```
+
+Tell the user to review and refine the generated alt text for their specific audience.
+
+---
+
+## Step 9 · Typst-author handoff
+
+When the chart is destined for a full typst-author document (not a standalone file):
+
+1. Generate the `#plot(...)` block without `#set page(...)`.
+2. Tell the user:
+
+> Paste the `#plot(...)` block inside a `#figure()` in your document:
+>
+> ```typst
+> #let p = plot(
+>   // ... your plot arguments ...
+>   width: 12cm, height: 9cm,
+> )
+>
+> #figure(
+>   p,
+>   caption: [Your caption here.],
+>   alt: get-alt-text(p),
+> )
+> ```
+>
+> Remove `#set page(...)` if you added it during standalone testing — the enclosing typst-author document controls page geometry.
+
+---
+
+## Step 10 · Anti-patterns
+
+Never emit these. Each has a correct alternative.
+
+| Wrong | Correct | Why |
+|---|---|---|
+| `aes(x: col-name)` | `aes(x: "col-name")` | Column names must be quoted strings; unquoted is a Typst identifier |
+| `aes(colour: "cyl")` when cyl holds `"4"/"6"/"8"` | `aes(colour: as-factor("cyl"))` | Numeric-looking strings need `as-factor()` for correct discrete training |
+| `element-text(font: "MyFont")` | `element-text(family: "MyFont")` | The param is `family:`, not `font:` |
+| `element-line(linewidth: 0.5pt)` | `element-line(thickness: 0.5pt)` | The param is `thickness:`, not `linewidth:` |
+| `scale-y-continuous()` when y values are small | Omit the scale | Unnecessary boilerplate; defaults are fine |
+| `#grid(columns: 2)[#p1][#p2]` for multi-panel | `#compose(p1, p2, layout: "grid", columns: 2)` | Typst `grid()` bypasses gribouille's legend hoisting |
+| `labs(title: "*Bold*")` | `labs(title: typst("*Bold*"))` | Raw strings in labs are not parsed as Typst markup |
+| `plot(..., data: csv("f.csv"))` | `#let d = csv("f.csv", row-type: dictionary)` then `plot(data: d, ...)` | `csv()` must use `row-type: dictionary` and be called outside `plot()` |
+| `geom-histogram()` without an `x` mapping | `mapping: aes(x: "col")` always | Histogram requires a single `x` aesthetic |
+| Omitting `width:` and `height:` | Always include `width: 12cm, height: 9cm` | Gribouille requires explicit dimensions; there is no default |
+| `geom-smooth(method: "loess")` | `geom-smooth(method: "lm")` | v1 only supports `method: "lm"` — loess and glm are not available |
+| `plot(..., defer: false)` inside `compose()` | `plot(..., defer: true)` | `compose()` only works with deferred specs |
+| `scale-size-radius()` | `scale-radius()` | The export is `scale-radius`, not `scale-size-radius` |
+| `scale-size-area(max.size: 6pt)` | `scale-size-area(range: (1pt, 12pt))` | The param is `range:`, not `max.size:` |
+| `n.breaks:` in any scale | `n-breaks:` | Gribouille uses hyphens (Typst convention), not dots |
+
+---
+
+## Quick reference
+
+**Three built-in datasets:**
+
+| Symbol | Description | Key columns |
+|---|---|---|
+| `penguins` | Palmer Archipelago penguins | `flipper-len`, `body-mass`, `species`, `island`, `sex` |
+| `mpg` | Fuel economy (ggplot2 mpg) | `displ`, `hwy`, `cty`, `class`, `cyl`, `drv` |
+| `economics` | US economic time series | `date`, `unemploy`, `pop`, `psavert`, `uempmed` |
+
+**Utility functions:**
+
+| Function | Purpose |
+|---|---|
+| `as-factor("col")` | Force column to discrete treatment |
+| `as-numeric("col")` | Force column to continuous |
+| `typst("markup")` | Typst markup in labs fields |
+| `after-scale(fn)` | Late-binding: evaluated after scale training |
+| `after-stat(fn)` | Late-binding: evaluated after stat transform |
+| `get-alt-text(p)` | Generate alt text from a plot result |
+| `format-comma()` | Number formatter: 1,234,567 |
+| `format-percent()` | Number formatter: 12.3% |
+| `format-scientific()` | Number formatter: 1.23×10⁴ |
+| `format-currency()` | Number formatter: $1,234 |
+| `format-number(digits: N)` | Fixed decimal places |
+| `format-wrap(width: N)` | Word-wrap labels at N characters |
+
+**Three theme presets:**
+
+| Theme | Character |
+|---|---|
+| `theme-minimal()` | No background panel, minimal chrome — default |
+| `theme-classic()` | Classic R style with axis lines |
+| `theme-void()` | No axes, no grid, just data |
diff --git a/2026/2026-05-17-gribouille/gribouille-skill/references/geom-table.md b/2026/2026-05-17-gribouille/gribouille-skill/references/geom-table.md
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+# Gribouille Geom Reference
+
+Full parameter reference for every geom exported in `lib.typ`. All parameters verified against source code.
+
+Columns: **Geom** | **Primary aes channels** | **Key params** | **Best used when**
+
+---
+
+## Point / scatter family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-point` | x, y, colour, fill, shape, size, alpha | `size` (default auto), `stroke` (outline), `alpha`, `shape` | Scatter plots; discrete x vs continuous y |
+| `geom-jitter` | x, y, colour, fill, shape, size, alpha | `size`, `stroke: 0.5pt`, `fill`, `colour`, `alpha`, `shape`; position defaults to `"jitter"` | Overplotted categoricals; combine with `geom-boxplot` |
+| `geom-count` | x, y, colour, fill, shape | `size: 3pt`, `stroke: none`, `fill`, `colour`, `alpha`, `shape` | Overplotted integer grids; size encodes count |
+| `geom-dotplot` | x, fill | `bins: 30`, `binwidth`, `dotsize: 1.0`, `stackratio: 1.0`, `fill`, `colour`, `stroke`, `alpha` | Dot histogram; alternative to `geom-histogram` |
+| `geom-rug` | x, y, colour | `sides: "bl"` (b=bottom, l=left, t=top, r=right), `length: 0.15cm`, `stroke: 0.4pt`, `colour`, `alpha` | Marginal data density; stack with another geom |
+
+## Line / path family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-line` | x, y, colour, linetype, alpha | `stroke: 0.8pt`, `colour`, `alpha`, `linetype` | Time series; connected data sorted by x |
+| `geom-path` | x, y, colour, linetype | `stroke: 0.8pt`, `colour`, `alpha`, `linetype` | Lines connected in data-row order (not sorted by x) |
+| `geom-step` | x, y, colour, linetype | `direction: "hv"\|"vh"\|"mid"`, `stroke: 0.8pt`, `colour`, `alpha`, `linetype` | Step functions; ECDF; survival curves |
+| `geom-area` | x, y, fill, alpha | `colour`, `fill`, `stroke: none`, `alpha` | Area under a line; stacked areas |
+| `geom-ribbon` | x, ymin, ymax, fill | `colour`, `fill`, `stroke: none`, `alpha` | Confidence bands; prediction intervals; pair with `geom-line` |
+| `geom-freqpoly` | x, colour, linetype | `bins: 30`, `binwidth`, `stroke: 0.8pt`, `colour`, `alpha`, `linetype` | Overlapping distributions as lines; alternative to `geom-histogram` |
+
+## Bar / column family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-bar` | x, fill, colour, alpha | `width: 0.9`, `colour`, `fill`, `stroke: none`, `alpha`, `position: "stack"` | Count bars; map `x` only, gribouille counts automatically |
+| `geom-col` | x, y, fill, colour, alpha | `width: 0.9`, `colour`, `fill`, `stroke: none`, `alpha`, `position: "identity"` | Pre-aggregated bar values; map both `x` and `y` |
+| `geom-histogram` | x, fill, colour, alpha | `bins: 30`, `binwidth`, `width: 1.0`, `colour`, `fill`, `stroke: none`, `alpha`, `position: "stack"` | Continuous variable distribution; requires `x` mapping |
+
+## Distribution summary family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-boxplot` | x, y (or y alone), fill, colour | `width: 0.6`, `colour`, `fill`, `stroke: 0.6pt`, `alpha`, `outlier-size: 1.8pt`, `outlier-colour: auto`, `whisker-cap: 0.5` | Distribution summary by group |
+| `geom-errorbar` | x, ymin, ymax, colour | `width: 0.4` (cap span; number=data units, length=panel units), `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Vertical error bars |
+| `geom-errorbarh` | y, xmin, xmax, colour | `height: 0.4` (cap span), `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Horizontal error bars |
+| `geom-linerange` | x, ymin, ymax, colour | `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Vertical range lines without caps |
+| `geom-crossbar` | x, y, ymin, ymax, fill, colour | `width: 0.6`, `colour`, `fill`, `stroke: 0.6pt`, `middle-stroke: 1.2pt`, `alpha` | Box without whiskers or outliers |
+| `geom-pointrange` | x, y, ymin, ymax, colour | `size: 2.5pt`, `stroke: 0.8pt`, `colour`, `fill`, `alpha`, `linetype: "solid"` | Point with range line |
+| `geom-smooth` | x, y, colour, fill | `method: "lm"` (only option in v1), `se: true` (show ribbon), `alpha: auto` (ribbon alpha), `level: 0.95` (CI level), `stroke: 1pt`, `colour`, `fill`, `linetype` | Fitted trend + optional confidence ribbon |
+| `geom-quantile` | x, y, colour, linetype | `quantiles: (0.25, 0.5, 0.75)`, `n-samples: 64`, `stroke: 0.6pt`, `colour`, `alpha`, `linetype`, `linewidth` | Quantile regression lines |
+
+## Annotation family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-text` | x, y, label, colour, alpha | `size: 8pt`, `colour`, `alpha`, `anchor: "center"` (CeTZ anchor), `dx: 0`, `dy: 0` | Data labels at point positions |
+| `geom-label` | x, y, label, colour, fill | `size: 8pt`, `colour`, `fill`, `stroke: 0.4pt`, `alpha`, `inset: 2pt`, `radius: 1pt`, `anchor: "center"`, `dx: 0`, `dy: 0` | Text with background box; callout labels |
+| `geom-typst` | x, y, label (Typst content) | `size: 10pt`, `colour`, `alpha`, `anchor: "center"`, `dx: 0`, `dy: 0`, `label: none` | Arbitrary Typst content at data coordinates |
+| `geom-hline` | yintercept | `yintercept` (scalar or array), `colour`, `stroke: 0.6pt`, `alpha`, `linetype: "solid"` | Horizontal reference line; does NOT inherit plot mapping |
+| `geom-vline` | xintercept | `xintercept` (scalar or array), `colour`, `stroke: 0.6pt`, `alpha`, `linetype: "solid"` | Vertical reference line; does NOT inherit plot mapping |
+| `geom-abline` | slope, intercept | `slope: 1`, `intercept: 0`, `colour`, `stroke: 0.6pt`, `alpha`, `linetype: "solid"` | Diagonal reference (y = a + bx); does NOT inherit plot mapping |
+| `geom-segment` | x, y, xend, yend, colour | `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Line segments between two data points |
+| `geom-curve` | x, y, xend, yend, colour | `curvature: 0.5`, `angle: 90deg`, `n: 32`, `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Curved connectors |
+| `geom-rect` | xmin, xmax, ymin, ymax, fill, colour | `colour`, `fill`, `stroke: none`, `alpha` | Shaded rectangular regions; highlight bands |
+| `geom-polygon` | x, y, fill, colour, group | `colour`, `fill`, `stroke: none`, `alpha` | Arbitrary filled polygons; map outlines |
+| `geom-blank` | — | `mapping: none`, `data: none` | Reserve plot area without drawing; useful for setting axis limits |
+
+## Group / density family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-mark` | colour, fill | `method: "rect"\|"circle"\|"ellipse"\|"hull"`, `expand: 0pt` (padding), `n: 64` (ellipse smoothness), `colour`, `fill`, `stroke: 0.5pt`, `alpha` | Group outlines; convex hull or enclosing shape per group |
+| `geom-ellipse` | x, y, colour, fill | `a: 1`, `b: 1` (semi-axes), `angle: 0`, `n: 64` (polygon segments), `colour`, `fill`, `stroke: none`, `alpha` | Manually sized ellipses at group centroids |
+
+## 2D density / grid family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-tile` | x, y, fill, colour | `width: 1`, `height: 1`, `colour`, `fill`, `stroke: none`, `alpha` | Heatmaps; requires pre-computed fill values |
+| `geom-bin-2d` | x, y, fill | `bins: 30`, `binwidth`, `colour`, `fill`, `stroke: none`, `alpha` | 2D histogram; bins both x and y |
+| `geom-hex` | x, y, fill | `bins: 30`, `binwidth`, `colour`, `fill`, `stroke: none`, `alpha` | Hexagonal binning; alternative to scatter for large N |
+| `geom-contour` | x, y, z, colour, linetype | (no user params beyond mapping) | Topographic contour lines on a regular grid |
+| `geom-contour-filled` | x, y, z, fill | (no user params beyond mapping) | Filled contour regions |
+
+## Specialised family
+
+| Geom | Primary aes | Key params | Best used when |
+|---|---|---|---|
+| `geom-spoke` | x, y, angle, radius | Fixed params: `angle: 0deg`, `radius: 1`, `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"` | Wind rose / directional vector field |
+| `geom-qq` | sample | `size`, `stroke: none`, `fill`, `colour`, `alpha`, `shape`, `distribution: "normal"` | Q-Q scatter plot |
+| `geom-qq-line` | sample | `stroke: 0.8pt`, `colour`, `alpha`, `linetype`, `distribution: "normal"` | Reference line for `geom-qq` |
+| `geom-function` | — | `fun` (callable `x => y`), `n: 101`, `xlim: none` (overrides x-domain), `stroke: 0.8pt`, `colour`, `alpha`, `linetype: "solid"`; does NOT inherit aes | Draw y = f(x) curve; no data needed |
+
+---
+
+## Stat helpers (used inside geoms via `stat:` param)
+
+Note: most geoms accept `stat: "identity"` (default) or a stat object. The common pattern is to use the geom's default stat.
+
+| Stat | Created by | Key params | Notes |
+|---|---|---|---|
+| `stat-bin(...)` | `geom-histogram` default | `bins: 30`, `binwidth: none` | Bin continuous x into counts |
+| `stat-count` | `geom-bar` default | — | Count rows per x level |
+| `stat-boxplot` | `geom-boxplot` default | — | Five-number summary per group |
+| `stat-smooth` | `geom-smooth` default | `method: "lm"`, `se: true`, `level: 0.95` | Fit linear model |
+| `stat-sum` | `geom-count` default | — | Count overlapping points |
+
+---
+
+## Position adjustments
+
+Pass these as the `position:` argument in geoms. String shortcuts (`"stack"`, `"dodge"`, `"fill"`, `"jitter"`, `"identity"`) also work.
+
+| Position | Key params | Notes |
+|---|---|---|
+| `position-stack()` | — | Stacked bars/areas |
+| `position-fill()` | — | 100% stacked bars |
+| `position-dodge(width: 0.9, padding: 0.1)` | `width`, `padding` | Side-by-side bars |
+| `position-jitter(width: 0.4, height: 0.4, seed: 0)` | `width`, `height`, `seed` | Jitter points |
+| `position-jitterdodge(...)` | `jitter.width`, `dodge.width` | Jitter within dodge |
+| `position-nudge(x: 0, y: 0)` | `x`, `y` | Offset text/labels |
+| `position-identity()` | — | No adjustment (default) |
+
+---
+
+## `geom-text` / `geom-label` anchor values
+
+Both `geom-text` and `geom-label` use CeTZ anchors, not ggplot2-style hjust/vjust:
+
+| Anchor | Meaning |
+|---|---|
+| `"center"` | Centred on point (default) |
+| `"north"` | Above point |
+| `"south"` | Below point |
+| `"east"` | Right of point |
+| `"west"` | Left of point |
+| `"north-east"` | Upper-right |
+| `"south-west"` | Lower-left |
+
+Use `dx` and `dy` (numbers in canvas units where 1 = 1cm, or Typst lengths) for fine offsets.
diff --git a/2026/2026-05-17-gribouille/gribouille-skill/references/scale-table.md b/2026/2026-05-17-gribouille/gribouille-skill/references/scale-table.md
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--- /dev/null
+++ b/2026/2026-05-17-gribouille/gribouille-skill/references/scale-table.md
@@ -0,0 +1,217 @@
+# Gribouille Scale Reference
+
+Full parameter reference for every scale family exported in `lib.typ`. All parameters verified against source code.
+
+Columns: **Scale** | **Aesthetic** | **Key params** | **When to use**
+
+---
+
+## Position scales — x axis
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-x-continuous(name, limits, breaks, labels, transform: "identity", expand, secondary)` | x | `name`, `limits`, `breaks`, `labels`, `transform` | Override x axis ticks, labels, or limits |
+| `scale-x-log10(name, limits, breaks, labels)` | x | `name`, `breaks`, `labels` | Log₁₀ x axis; data must be positive |
+| `scale-x-sqrt(name, limits, breaks, labels)` | x | `name`, `breaks`, `labels` | Square-root x axis |
+| `scale-x-reverse(name, limits, breaks, labels)` | x | `name` | Reverse x direction |
+| `scale-x-binned(name, limits, n-breaks: 10, labels)` | x | `n-breaks`, `labels`, `limits` | Bin continuous x into discrete intervals |
+| `scale-x-discrete(name, limits, labels, expand)` | x | `limits` (reorder levels), `labels` | Force discrete x; reorder categories |
+| `scale-x-date(name, limits, breaks, labels, date-format, expand)` | x | `date-format` (Typst datetime.display pattern) | Date x axis; values as numeric days since 2000-01-01 or ISO-8601 strings |
+| `scale-x-datetime(...)` | x | same as `scale-x-date` | Datetime x axis |
+| `scale-x-time(...)` | x | same as `scale-x-date` | Time-of-day x axis |
+
+## Position scales — y axis
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-y-continuous(name, limits, breaks, labels, transform: "identity", expand, secondary)` | y | same as `scale-x-continuous` | Override y axis |
+| `scale-y-log10(name, limits, breaks, labels)` | y | `name`, `breaks`, `labels` | Log₁₀ y axis |
+| `scale-y-sqrt(...)` | y | — | Square-root y axis |
+| `scale-y-reverse(...)` | y | — | Flip y direction |
+| `scale-y-binned(name, limits, n-breaks: 10, labels)` | y | `n-breaks`, `labels` | Bin continuous y |
+| `scale-y-discrete(name, limits, labels, expand)` | y | `limits`, `labels` | Force discrete y |
+| `scale-y-date(...)` | y | `date-format`, `limits`, `breaks` | Date y axis |
+| `scale-y-datetime(...)` | y | same | Datetime y axis |
+| `scale-y-time(...)` | y | same | Time-of-day y axis |
+
+---
+
+## Colour scales (discrete)
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-colour-discrete(name, palette, limits, labels)` | colour | `palette` (array of colours or `auto`), `limits` | Custom discrete colour palette |
+| `scale-colour-manual(values, name, limits, labels)` | colour | `values` (array of colours or dict `level -> colour`) | Explicit named mapping |
+| `scale-colour-identity(name)` | colour | — | Colour column holds literal colour values |
+| `scale-colour-okabe-ito(name, limits, labels)` | colour | — | Colourblind-safe 8-colour discrete palette |
+| `scale-colour-hue(hue, chroma, luminance, name, limits, labels)` | colour | `hue` (range, e.g. `(15deg, 375deg)`), `chroma: 100`, `luminance: 65` | Hue-based palette; tune saturation |
+| `scale-colour-grey(start, end, name, limits, labels)` | colour | `start: 0.2`, `end: 0.8` (grey levels 0–1) | Greyscale discrete |
+| `scale-colour-brewer(palette, name, limits, labels)` | colour | `palette: "Set1"` (ColorBrewer palette name) | ColorBrewer palettes |
+
+## Colour scales (continuous)
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-colour-continuous(name, palette, limits, breaks, labels)` | colour | `palette` (gradient or colour array) | Continuous colour from palette |
+| `scale-colour-gradient(low, high, name, limits, breaks, labels)` | colour | `low: rgb("#132B43")`, `high: rgb("#56B1F7")` | Simple two-colour gradient |
+| `scale-colour-gradient2(low, mid, high, midpoint, name, limits, breaks, labels)` | colour | `low`, `mid: white`, `high`, `midpoint: 0` | Diverging gradient centred at `midpoint` |
+| `scale-colour-gradientn(colours, name, limits, breaks, labels)` | colour | `colours` (array of 3+ colours) | Multi-stop gradient |
+| `scale-colour-distiller(palette, direction, name, limits, breaks, labels)` | colour | `palette: "Spectral"`, `direction: 1\|-1` | Brewer palettes interpolated to continuous |
+| `scale-colour-steps(low, high, n-breaks, name, limits, labels)` | colour | `low`, `high`, `n-breaks: 5` | Stepped two-colour gradient |
+| `scale-colour-steps2(low, mid, high, midpoint, n-breaks, name, limits, labels)` | colour | `low`, `mid: white`, `high`, `midpoint: 0`, `n-breaks: 5` | Stepped diverging gradient |
+| `scale-colour-stepsn(colours, n-breaks, name, limits, labels)` | colour | `colours`, `n-breaks: 5` | Stepped multi-stop gradient |
+| `scale-colour-fermenter(palette, n-breaks, direction, name, limits, labels)` | colour | `palette: "Spectral"`, `n-breaks: 5`, `direction: 1` | Brewer palettes cut into discrete bins |
+
+## Colour scales (viridis family)
+
+Supported `option` values: `"viridis"` (default), `"magma"`, `"plasma"`, `"inferno"`, `"cividis"`.
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-colour-viridis-c(option, name, limits, breaks, labels)` | colour | `option: "viridis"` | Perceptually uniform continuous colour |
+| `scale-colour-viridis-d(option, name, limits, labels)` | colour | `option: "viridis"` | Perceptually uniform discrete colour |
+| `scale-colour-viridis-b(option, n-breaks, name, limits, labels)` | colour | `option: "viridis"`, `n-breaks: 5` | Perceptually uniform binned colour |
+
+## Fill scales
+
+Every colour scale above has an exact fill counterpart. Replace `colour` with `fill`:
+
+```
+scale-fill-discrete()         scale-fill-continuous()
+scale-fill-manual()           scale-fill-gradient()
+scale-fill-identity()         scale-fill-gradient2()
+scale-fill-okabe-ito()        scale-fill-gradientn()
+scale-fill-hue()              scale-fill-brewer()
+scale-fill-grey()             scale-fill-distiller()
+scale-fill-viridis-c()        scale-fill-fermenter()
+scale-fill-viridis-d()        scale-fill-steps()
+scale-fill-viridis-b()        scale-fill-steps2()
+                              scale-fill-stepsn()
+```
+
+---
+
+## Alpha scales
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-alpha-continuous(name, range, limits, breaks, labels)` | alpha | `range: (0.1, 1)` | Map a continuous variable to transparency |
+| `scale-alpha-binned(n-breaks, range, name, limits, labels)` | alpha | `n-breaks: 4`, `range: (0.1, 1)` | Binned (stepped) alpha |
+| `scale-alpha-manual(values, name, limits, labels)` | alpha | `values` (array of 0–1 values) | Explicit alpha per level |
+| `scale-alpha-identity(name)` | alpha | — | Alpha column holds literal 0–1 values |
+
+---
+
+## Size scales
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-size-continuous(name, range, limits, breaks, labels)` | size | `range: (1pt, 6pt)` | Map continuous var to point size |
+| `scale-radius(name, range, limits, breaks, labels)` | size | `range: (1pt, 6pt)` | Alias of `scale-size-continuous`; map to radius |
+| `scale-size-area(name, range, limits, breaks, labels)` | size | `range: (1pt, 6pt)` | Map to area (perceptually correct for magnitude) |
+| `scale-size-binned(n-breaks, range, name, limits, labels)` | size | `n-breaks: 4`, `range: (1pt, 6pt)` | Binned size scale |
+| `scale-size-binned-area(n-breaks, range, name, limits, labels)` | size | `n-breaks: 4`, `range: (1pt, 6pt)` | Binned area scale |
+| `scale-size-identity(name)` | size | — | Size column holds literal length values |
+| `scale-size-manual(values, name, limits, labels)` | size | `values` (array of lengths) | Explicit size per level |
+
+---
+
+## Linewidth scales
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-linewidth-continuous(name, range, limits, breaks, labels)` | linewidth | `range: (0.4pt, 1.4pt)` | Map continuous var to line width |
+| `scale-linewidth-binned(n-breaks, range, name, limits, labels)` | linewidth | `n-breaks: 4`, `range: (0.4pt, 1.4pt)` | Binned linewidth |
+| `scale-linewidth-manual(values, name, limits, labels)` | linewidth | `values` (array of lengths) | Explicit linewidth per level |
+| `scale-linewidth-identity(name)` | linewidth | — | Linewidth column holds literal length values |
+
+---
+
+## Shape / linetype scales
+
+| Scale | Aesthetic | Key params | When to use |
+|---|---|---|---|
+| `scale-shape(name, palette, limits, labels)` | shape | `palette` (array of shape keywords or `auto`) | Discrete point shapes |
+| `scale-shape-manual(values, name, limits, labels)` | shape | `values` (array of shape keywords) | Explicit shape per level |
+| `scale-shape-identity(name)` | shape | — | Shape column holds literal keywords |
+| `scale-shape-binned(n-breaks, palette, name, limits, labels)` | shape | `n-breaks: 4`, `palette` | Binned shape scale |
+| `scale-linetype(name, palette, limits, labels)` | linetype | `palette` (array of dash keywords or `auto`) | Discrete line types |
+| `scale-linetype-manual(values, name, limits, labels)` | linetype | `values` (array of dash keywords) | Explicit linetype per level |
+| `scale-linetype-identity(name)` | linetype | — | Linetype column holds literal keywords |
+| `scale-linetype-binned(n-breaks, palette, name, limits, labels)` | linetype | `n-breaks: 4`, `palette` | Binned linetype scale (continuous var) |
+| `scale-linetype-continuous(name, palette, limits, labels)` | linetype | alias of `scale-linetype-binned(n-breaks: 4)` | Alias |
+| `scale-linetype-discrete(name, palette, limits, labels)` | linetype | alias of `scale-linetype()` | Alias |
+
+Shape keywords: `"circle"`, `"square"`, `"triangle"`, `"diamond"`, `"cross"`, `"x"`, `"star"`, `"triangle-down"`
+
+Linetype keywords: `"solid"`, `"dashed"`, `"dotted"`, `"dash-dotted"`, `"densely-dashed"`, `"loosely-dashed"`
+
+---
+
+## Format helpers (use in `labels:` parameter)
+
+| Function | Output example | Notes |
+|---|---|---|
+| `format-comma()` | 1,234,567 | Thousands separator; best for y-axis with large integers |
+| `format-percent()` | 12.3% | Multiply by 100 and append %; input should be 0–1 |
+| `format-scientific()` | 1.23×10⁴ | Scientific notation |
+| `format-currency()` | $1,234 | Dollar prefix + comma separator |
+| `format-number(digits: N)` | 3.14 | Fixed decimal places |
+| `format-lower()` | lowercase | Convert labels to lowercase |
+| `format-upper()` | UPPERCASE | Convert labels to uppercase |
+| `format-title()` | Title Case | Capitalise each word |
+| `format-wrap(width: N)` | wrapped text | Word-wrap long labels at N characters |
+
+---
+
+## Common patterns
+
+**Large y-axis numbers:**
+```typst
+scales: (scale-y-continuous(labels: format-comma()),)
+```
+
+**Log-log axes:**
+```typst
+scales: (scale-x-log10(), scale-y-log10(),)
+```
+
+**Custom discrete colour palette:**
+```typst
+scales: (
+  scale-colour-manual(
+    values: ("Setosa": rgb("#E69F00"), "Versicolor": rgb("#56B4E9"), "Virginica": rgb("#009E73")),
+    limits: ("Setosa", "Versicolor", "Virginica"),
+  ),
+)
+```
+
+**Colourblind-safe palette:**
+```typst
+scales: (scale-colour-okabe-ito(),)
+```
+
+**Viridis continuous fill for heatmap:**
+```typst
+scales: (scale-fill-viridis-c(option: "viridis"),)
+```
+
+**Diverging colour centred at zero:**
+```typst
+scales: (scale-colour-gradient2(low: blue, mid: white, high: red, midpoint: 0),)
+```
+
+**Reorder discrete x axis:**
+```typst
+scales: (scale-x-discrete(limits: ("small", "medium", "large")),)
+```
+
+**Date axis:**
+```typst
+scales: (scale-x-date(date-format: "[month repr:short] [year]"),)
+```
+
+**Size range for bubble chart:**
+```typst
+scales: (scale-size-area(range: (1pt, 12pt)),)
+```