diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b0937d..a22aef9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -66,6 +66,33 @@ base** rather than reusing `base-6f3b20266de1`.
   read-only preview, and an on-host `curl` that tells "chain up" (`403`) from
   "Studio down or on another port" (empty reply). A remote session hit exactly
   that: Studio was started on `18765` while only `8765` is published.
+- **README said PDF export from Studio works out of the box. It does not.**
+  Since v1.4.0 (`67da05b`) the README's Studio section has said that
+  `/studio-pdf` and `studio_export_pdf` use `typst`. Since v1.9.1
+  (`6353d59`) the image-tags section has also said that "PDF export from
+  Studio/pandoc works out of the box". That holds for pandoc run directly
+  (`pandoc doc.md --pdf-engine=typst -o doc.pdf`), but not for Studio.
+  pi-studio runs pandoc with `$PANDOC_PDF_ENGINE`, falling back to `xelatex`,
+  and the image has never set that variable (`git log -S PANDOC_PDF_ENGINE`
+  finds no commit). So `/studio-pdf` and `studio_export_pdf` fail with
+  `xelatex not found`. That was seen at v1.6.3 and again at v1.11.2. The
+  README now says so in both places that made the claim, and adds a
+  "PDF export from Studio needs LaTeX" section with two warnings and a
+  working recipe:
+  - **Setting `PANDOC_PDF_ENGINE=typst` makes it worse.** The error message
+    suggests it, but pi-studio adds its own LaTeX header to the document
+    (unless the document sets `header-includes`). Under typst, pandoc exits
+    0 and prints that header as text above the first heading. Seen in the same PDF through two renderers, MuPDF and
+    Chromium.
+  - **`texlive-xetex` alone, which the README offered as the fallback, is
+    not enough.** The export then still lacks `lmodern.sty`, `ulem.sty`
+    and the `pzdr` font. Adding `lmodern texlive-plain-generic
+    texlive-fonts-recommended` makes it work: 37 packages and 491 MB
+    installed, after `apt-get update`. Measured on v1.11.2 with pi-studio
+    0.10.1. The exported page was looked at, not only its exit code.
+
+  The same claim also appears in `AGENTS.md` ("What we DON'T install") and
+  in comments in `Dockerfile.base`. Neither is changed here.
 
 ## v1.11.2 — 2026-10-14
 
diff --git a/README.md b/README.md
index 22a8aee..b422d06 100644
--- a/README.md
+++ b/README.md
@@ -175,10 +175,12 @@ Currently published:
 | `joakimp/pi-devbox:latest-studio` | `latest` + [pi-studio](https://github.com/omaclaren/pi-studio) (browser prompt editor, KaTeX/Mermaid preview, tmux-backed literate REPLs) | ~3.25 GB |
 | `joakimp/pi-devbox:vX.Y.Z-studio` | pinned-version studio equivalent | ~3.25 GB |
 
-Both variants ship **`typst`** as the pandoc PDF engine
-(`pandoc --pdf-engine=typst`), a single ~30 MB static binary, so PDF export from
-Studio/pandoc works out of the box — no separate `-tex` variant needed.
-`texlive-xetex` stays the higher-fidelity fallback (install on demand).
+Both variants ship **`typst`**, a single ~30 MB static binary, as a PDF engine
+for pandoc, so `pandoc doc.md --pdf-engine=typst -o doc.pdf` works out of the
+box (see [Generating a PDF with pandoc + typst](#generating-a-pdf-with-pandoc--typst)).
+**pi-studio's PDF export does not use typst.** `/studio-pdf` and
+`studio_export_pdf` need a LaTeX engine, which neither variant ships (see
+[PDF export from Studio needs LaTeX](#pdf-export-from-studio-needs-latex)).
 
 ## Using pi-studio (`-studio` variant)
 
@@ -345,10 +347,43 @@ Assuming the compose file publishes `127.0.0.1:8765:8765` (see method B):
 > an empty reply means the bridge has nothing behind it, i.e. Studio is down
 > or on another port.
 
-> PDF export (`/studio-pdf`, `studio_export_pdf`) uses **`typst`**, shipped in
-> the base image as the pandoc PDF engine (`pandoc --pdf-engine=typst`). For
-> LaTeX-exact output you can install `texlive-xetex` on demand as a heavier
-> fallback. HTML export, KaTeX, Mermaid, and all REPL features work regardless.
+### PDF export from Studio needs LaTeX
+
+Studio's PDF export (`/studio-pdf` and the `studio_export_pdf` tool) fails out
+of the box:
+
+```text
+pandoc PDF export failed with exit code 47: xelatex not found
+```
+
+pi-studio runs pandoc with the engine named in `PANDOC_PDF_ENGINE`, and uses
+`xelatex` when that is unset. The image ships no LaTeX engine and does not set
+`PANDOC_PDF_ENGINE`. HTML export, KaTeX, Mermaid and the REPLs are not
+affected.
+
+**Do not set `PANDOC_PDF_ENGINE=typst`**, even though the error message
+suggests setting it. pi-studio adds its own LaTeX header
+(`\usepackage{titlesec}`, `\titleformat…`) to the document, and typst does
+not understand LaTeX. pandoc exits 0, and the header is printed as text above
+your first heading. There is no error, only a wrong PDF.
+
+There are two ways out:
+
+- **Run pandoc yourself** (nothing to install):
+  `pandoc doc.md --pdf-engine=typst -o doc.pdf`. See the next section.
+- **Install the LaTeX packages Studio needs.** This adds 37 packages and
+  about 490 MB, and they are gone when the container is recreated:
+
+  ```bash
+  sudo apt-get update
+  sudo apt-get install -y --no-install-recommends \
+    texlive-xetex lmodern texlive-plain-generic texlive-fonts-recommended
+  ```
+
+  `texlive-xetex` on its own is not enough. Studio's export then still lacks
+  `lmodern.sty`, `ulem.sty` and the `pzdr` font, which come from the other
+  three packages. The image starts with an empty package index, so run
+  `apt-get update` first. (Measured on v1.11.2 with pi-studio 0.10.1.)
 
 ### Generating a PDF with pandoc + typst