From 72aaf17f9eba42e87fd3f29e46fd009a2ca6c249 Mon Sep 17 00:00:00 2001
From: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>
Date: Fri, 23 Oct 2026 01:34:48 +0200
Subject: [PATCH 1/4] chore(r): render R implementations on R 4.6.1 with
 ggplot2 4.0.3

The shared setup-r action installs R 4.6.1 (was 4.4.1) and pins the Posit
Package Manager snapshot to 2026-10-20 (was 2025-01-15), which moves
ggplot2 from 3.5.1 to 4.0.3. Every package in the list installs as a
noble binary for R 4.6.1 from that snapshot.

All 325 ggplot2 implementations render in both themes before and after
(container run mirroring the action). The ggplot2 generator prompt gains a
"ggplot2 4.0 rules" section for the changes that render differently
without an error: label borders, binning edges, theme_void() borders,
rotated top-axis text, legend order, fatten/draw_quantiles/errorbarh
deprecations. core/constants.py shows ggplot2 4.0.3 and R 4.6.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .github/actions/setup-r/action.yml | 12 ++++++---
 changelog.d/r-4.6-ggplot2-4.md     | 10 +++++++
 prompts/library/ggplot2.md         | 43 ++++++++++++++++++++++++++++--
 3 files changed, 60 insertions(+), 5 deletions(-)
 create mode 100644 changelog.d/r-4.6-ggplot2-4.md

diff --git a/.github/actions/setup-r/action.yml b/.github/actions/setup-r/action.yml
index aabd8132031..197ea928929 100644
--- a/.github/actions/setup-r/action.yml
+++ b/.github/actions/setup-r/action.yml
@@ -9,7 +9,9 @@ inputs:
   r-version:
     description: "R version to install"
     required: false
-    default: "4.4.1"
+    # Bump together with the snapshot date below: Posit Package Manager serves
+    # noble binaries per R minor version, so a new R needs a snapshot that has them.
+    default: "4.6.1"
 
 runs:
   using: "composite"
@@ -51,13 +53,17 @@ runs:
       # matches the current ubuntu-latest runner image — update if GitHub moves
       # the runner OS, and bump the snapshot date deliberately.
       #
-      # Snapshot 2025-01-15 ships ggplot2 3.5.1. The repository has no R lock
+      # Snapshot 2026-10-20 ships ggplot2 4.0.3. The repository has no R lock
       # file, so this line stands in for one: core/library_versions.py reads
       # ggplot2's version from it for the database sync, but only while its date
       # is the one in the URL below. A new snapshot date fails
       # tests/unit/core/test_version_sources.py until this line names the ggplot2
       # version the new snapshot installs (packageVersion("ggplot2") in a run).
       #
+      # Every package below installs from this snapshot as a noble binary for
+      # R 4.6.1. ggplot2 4.0 changes rendering defaults; the changes that matter
+      # to generated code are listed in prompts/library/ggplot2.md.
+      #
       # dependencies is restricted to required types (Depends/Imports/LinkingTo);
       # the default `NA` is identical but explicit is clearer. `TRUE` would also
       # pull in Suggests (sf, Hmisc, maps, quantreg, ...) — none of which the
@@ -67,7 +73,7 @@ runs:
       run: |
         Rscript -e '
           options(
-            repos = c(CRAN = "https://packagemanager.posit.co/cran/__linux__/noble/2025-01-15"),
+            repos = c(CRAN = "https://packagemanager.posit.co/cran/__linux__/noble/2026-10-20"),
             Ncpus = parallel::detectCores()
           )
           install.packages(
diff --git a/changelog.d/r-4.6-ggplot2-4.md b/changelog.d/r-4.6-ggplot2-4.md
new file mode 100644
index 00000000000..d1c2294ff80
--- /dev/null
+++ b/changelog.d/r-4.6-ggplot2-4.md
@@ -0,0 +1,10 @@
+### Changed
+
+- **R implementations now render on R 4.6.1 with ggplot2 4.0.3.** The shared R
+  setup action installs R 4.6.1 and pins the Posit Package Manager snapshot to
+  2026-10-20 (was R 4.4.1 and 2025-01-15, ggplot2 3.5.1). The ggplot2 generator
+  prompt gains a "ggplot2 4.0 rules" section for the changes that render
+  differently without an error: label borders, binning edges, `theme_void()`
+  borders, rotated top-axis text and legend order. All 325 ggplot2
+  implementations still render in both themes; existing catalogue images stay
+  as they are until an implementation is regenerated.
diff --git a/prompts/library/ggplot2.md b/prompts/library/ggplot2.md
index 2476dd02922..59a8b6d7feb 100644
--- a/prompts/library/ggplot2.md
+++ b/prompts/library/ggplot2.md
@@ -2,7 +2,9 @@
 
 ggplot2 is the canonical implementation of the grammar of graphics in R. This
 is anyplot's first R-language entry; the file extension is **`.R`** and the
-runtime is **Rscript**, not Python.
+runtime is **Rscript**, not Python. The CI runtime is **R 4.6 with ggplot2 4.0**
+(pinned in `.github/actions/setup-r/action.yml`): write against the 4.0 API in
+"ggplot2 4.0 rules" below, not 3.x habits.
 
 ## IMPORTANT: No Workarounds
 
@@ -277,7 +279,8 @@ ggsave(
 ## R-Specific Gotchas
 
 - Use `linewidth =` for `geom_line()` and `element_line()` in modern ggplot2
-  (≥ 3.4). `size =` triggers a deprecation warning.
+  (≥ 3.4). `size =` triggers a deprecation warning, and on `geom_bar()` /
+  `geom_col()` outlines ggplot2 4.0 ignores it entirely.
 - `theme()` chains compose right-to-left: a later `theme()` overrides an
   earlier one. Start with `theme_minimal(base_size = ...)`, then layer
   `anyplot_theme`.
@@ -288,3 +291,39 @@ ggsave(
   removed in dplyr ≥ 1.0; `tibble::tibble` is the correct path.
 - Avoid `print(p)` at script end — `ggsave()` already renders the plot, and an
   extra `print()` opens an unused interactive device.
+
+## ggplot2 4.0 rules
+
+Each rule below changed between ggplot2 3.5 and 4.0: the old form still runs,
+but renders differently or prints a deprecation warning.
+
+- **Label borders:** set the border width with `linewidth` (`0` for no border)
+  and its colour with `border.colour`. `label.size` is deprecated, and
+  `annotate("label", ..., label.size = 0)` is ignored outright ("Ignoring
+  unknown parameters"), so the label gets the default 0.25 mm border.
+- **Horizontal error bars:** `geom_errorbar(aes(y = term, xmin = lo, xmax = hi),
+  orientation = "y", width = 0.2)`. `geom_errorbarh()` is deprecated.
+- **Box, crossbar, pointrange:** `fatten` is deprecated. Style the parts
+  directly: `geom_boxplot(median.linewidth = , box.linewidth = ,
+  whisker.linewidth = )`, `geom_crossbar(middle.linewidth = )`, and the point
+  `size` in `geom_pointrange()`.
+- **Violin quantiles:** `geom_violin(quantiles = c(0.25, 0.5, 0.75),
+  quantile.linetype = 1)`. `draw_quantiles` is deprecated, and quantiles are now
+  computed from the data rather than from the density.
+- **Histograms and other binning stats:** pass `boundary` (or explicit `breaks`)
+  together with `binwidth` or `bins`, for example `binwidth = 5, boundary = 0`.
+  ggplot2 4.0 moved the default bin edges, so unanchored bins shift between
+  versions and rarely land on round values.
+- **`theme_void()` borders:** its root `rect` now has `linewidth = 0`, so a border
+  such as `legend.background = element_rect(fill = ELEVATED_BG, color = INK_SOFT)`
+  disappears. Give every bordered `element_rect()` an explicit `linewidth`.
+- **Rotated axis text:** set both `hjust` and `vjust`. On a top axis
+  (`scale_x_discrete(position = "top")`) use `vjust = 0`; without it ggplot2 4.0
+  pushes the labels up into the title.
+- **Several legends:** fix their order with `guides(colour = guide_legend(order
+  = 1), size = guide_legend(order = 2))`. The default order changed in 4.0 and is
+  not stable across versions.
+- **Subtitle and caption** inherit from `text`, no longer from `title`: style
+  `plot.subtitle` and `plot.caption` explicitly instead of through `title`.
+- **Renamed:** `coord_transform()` replaces `coord_trans()`, and
+  `facet_wrap(dir = )` replaces `as.table`.

From f2c9e69b4fb9374baa2b42b0796cc066af54c5b6 Mon Sep 17 00:00:00 2001
From: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>
Date: Fri, 23 Oct 2026 01:35:49 +0200
Subject: [PATCH 2/4] docs(changelog): add the PR reference to the R 4.6
 fragment

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 changelog.d/r-4.6-ggplot2-4.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/changelog.d/r-4.6-ggplot2-4.md b/changelog.d/r-4.6-ggplot2-4.md
index d1c2294ff80..e85023dff30 100644
--- a/changelog.d/r-4.6-ggplot2-4.md
+++ b/changelog.d/r-4.6-ggplot2-4.md
@@ -7,4 +7,4 @@
   differently without an error: label borders, binning edges, `theme_void()`
   borders, rotated top-axis text and legend order. All 325 ggplot2
   implementations still render in both themes; existing catalogue images stay
-  as they are until an implementation is regenerated.
+  as they are until an implementation is regenerated. (#12242)

From 7136fb0d339d7f4daf61a97f450a0f4203bbf987 Mon Sep 17 00:00:00 2001
From: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>
Date: Fri, 23 Oct 2026 01:43:18 +0200
Subject: [PATCH 3/4] docs(prompts): tighten the ggplot2 4.0 notes after the
 first review

Rename the section to notes so the reviewer, which also reads this file,
does not take it as a scoring rubric. Spell out the facet_wrap(dir) layout
that replaces as.table = FALSE (checked: identical panel layout), and add
the annotation_borders() rename and plot.tag inheritance.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 changelog.d/r-4.6-ggplot2-4.md |  2 +-
 prompts/library/ggplot2.md     | 17 +++++++++++------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/changelog.d/r-4.6-ggplot2-4.md b/changelog.d/r-4.6-ggplot2-4.md
index e85023dff30..691604bcd7b 100644
--- a/changelog.d/r-4.6-ggplot2-4.md
+++ b/changelog.d/r-4.6-ggplot2-4.md
@@ -3,7 +3,7 @@
 - **R implementations now render on R 4.6.1 with ggplot2 4.0.3.** The shared R
   setup action installs R 4.6.1 and pins the Posit Package Manager snapshot to
   2026-10-20 (was R 4.4.1 and 2025-01-15, ggplot2 3.5.1). The ggplot2 generator
-  prompt gains a "ggplot2 4.0 rules" section for the changes that render
+  prompt gains a "ggplot2 4.0 notes" section for the changes that render
   differently without an error: label borders, binning edges, `theme_void()`
   borders, rotated top-axis text and legend order. All 325 ggplot2
   implementations still render in both themes; existing catalogue images stay
diff --git a/prompts/library/ggplot2.md b/prompts/library/ggplot2.md
index 59a8b6d7feb..05e67d9f0ff 100644
--- a/prompts/library/ggplot2.md
+++ b/prompts/library/ggplot2.md
@@ -4,7 +4,7 @@ ggplot2 is the canonical implementation of the grammar of graphics in R. This
 is anyplot's first R-language entry; the file extension is **`.R`** and the
 runtime is **Rscript**, not Python. The CI runtime is **R 4.6 with ggplot2 4.0**
 (pinned in `.github/actions/setup-r/action.yml`): write against the 4.0 API in
-"ggplot2 4.0 rules" below, not 3.x habits.
+"ggplot2 4.0 notes" below, not 3.x habits.
 
 ## IMPORTANT: No Workarounds
 
@@ -292,9 +292,9 @@ ggsave(
 - Avoid `print(p)` at script end — `ggsave()` already renders the plot, and an
   extra `print()` opens an unused interactive device.
 
-## ggplot2 4.0 rules
+## ggplot2 4.0 notes
 
-Each rule below changed between ggplot2 3.5 and 4.0: the old form still runs,
+Each item below changed between ggplot2 3.5 and 4.0: the old form still runs,
 but renders differently or prints a deprecation warning.
 
 - **Label borders:** set the border width with `linewidth` (`0` for no border)
@@ -323,7 +323,12 @@ but renders differently or prints a deprecation warning.
 - **Several legends:** fix their order with `guides(colour = guide_legend(order
   = 1), size = guide_legend(order = 2))`. The default order changed in 4.0 and is
   not stable across versions.
-- **Subtitle and caption** inherit from `text`, no longer from `title`: style
-  `plot.subtitle` and `plot.caption` explicitly instead of through `title`.
+- **Subtitle, caption and tag** inherit from `text`, no longer from `title`:
+  style `plot.subtitle`, `plot.caption` and `plot.tag` explicitly instead of
+  through `title`.
 - **Renamed:** `coord_transform()` replaces `coord_trans()`, and
-  `facet_wrap(dir = )` replaces `as.table`.
+  `annotation_borders()` replaces `borders()`.
+- **Facet panel order:** `facet_wrap(as.table = )` is deprecated. Set the order
+  with a two-letter `dir` instead: the letters name the starting corner and the
+  first one the filling direction, so `dir = "lb"` starts bottom-left and fills
+  left to right, as `as.table = FALSE` did.

From 8e503430153d8534dfa08c653e44651fb42aee86 Mon Sep 17 00:00:00 2001
From: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>
Date: Fri, 23 Oct 2026 12:03:02 +0200
Subject: [PATCH 4/4] docs(prompts): state the ggplot2 API level like the other
 library prompts

After #12240 every locked library's prompt names the major it writes against;
tests/unit/core/test_version_sources.py holds ggplot2's line to the snapshot
note in the setup-r action (4.0.3, so API level 4).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0175hA62juZoajMcqKxWFGza
---
 prompts/library/ggplot2.md | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/prompts/library/ggplot2.md b/prompts/library/ggplot2.md
index 05e67d9f0ff..f1589a65ec2 100644
--- a/prompts/library/ggplot2.md
+++ b/prompts/library/ggplot2.md
@@ -2,9 +2,11 @@
 
 ggplot2 is the canonical implementation of the grammar of graphics in R. This
 is anyplot's first R-language entry; the file extension is **`.R`** and the
-runtime is **Rscript**, not Python. The CI runtime is **R 4.6 with ggplot2 4.0**
-(pinned in `.github/actions/setup-r/action.yml`): write against the 4.0 API in
-"ggplot2 4.0 notes" below, not 3.x habits.
+runtime is **Rscript**, not Python.
+
+**API level:** ggplot2 4. The Posit snapshot in `.github/actions/setup-r/action.yml`
+pins this major; write against its API, with the changes in "ggplot2 4.0 notes"
+below, not 3.x habits.
 
 ## IMPORTANT: No Workarounds