feat(base): ship typst as lightweight pandoc PDF engine

pandoc has been in the base since v1.0.0 but only as a front-end; PDF
export (studio_export_pdf / pandoc -o out.pdf) failed with 'xelatex not
found' because no back-end engine was installed. Ship typst (~30 MB
static Rust binary, no LaTeX) as the default engine via
`pandoc --pdf-engine=typst`, chosen over a ~600 MB TeX Live install.
texlive-xetex remains the higher-fidelity install-on-demand fallback.

- Dockerfile.base: install typst (latest GitHub-release idiom, pin via
  TYPST_VERSION); add xz-utils (typst ships .tar.xz); bump
  BASE_REBUILD_DATE. Lands in base-<hash>.
- smoke-test.sh: verify typst + a real pandoc --pdf-engine=typst render.
- README/AGENTS/CHANGELOG: typst now shipped (supersedes the planned
  :latest-studio-tex variant).

No tag pushed — CI build intentionally deferred.

AGENTS.md

@@ -153,14 +153,14 @@ deprecated artifacts (to be removed in opencode-devbox v2.0.0).
 
 ## What we DON'T install (and why)
 
-- **No texlive** (~600 MB–1 GB). Users who need PDF export from pandoc
-  or pi-studio can install on demand: `sudo apt-get install texlive-xetex
-  texlive-latex-recommended`. PDF export is planned for a future release — but
-  note pandoc alone can't render PDF (it needs a back-end engine), and a full TeX
-  install is heavy. A lightweight engine like **`typst`** (~30 MB static
-  binary, `pandoc --pdf-engine=typst`) is the preferred candidate and, being
-  small, could land in base rather than a dedicated `:latest-studio-tex`
-  variant. `texlive-xetex` stays the higher-fidelity fallback.
+- **No texlive** (~600 MB–1 GB). PDF export from pandoc / pi-studio works
+  out of the box via **`typst`** (~30 MB static binary), which the base ships
+  as the pandoc PDF engine (`pandoc --pdf-engine=typst`) — small enough to live
+  in base rather than a dedicated `:latest-studio-tex` variant. We don't bake in
+  a full TeX Live: it's heavy and typst covers the common Markdown→PDF case.
+  Users needing LaTeX-exact output can install the higher-fidelity fallback on
+  demand: `sudo apt-get install texlive-xetex texlive-latex-recommended` (then
+  `pandoc --pdf-engine=xelatex`).
 - **pi-studio** ships in the `:latest-studio` variant (since v1.1.0),
   vendored to `/opt/pi-studio` and registered at container start via
   `pi install /opt/pi-studio` (see Dockerfile.variant `INSTALL_STUDIO`).

CHANGELOG.md

@@ -11,6 +11,26 @@ Pre-v1.0.0 tags followed the pi npm version (`v{pi_version}[letter]`).
 
 ---
 
+## Unreleased
+
+### Added
+
+- **`typst` — lightweight PDF engine for pandoc (Markdown→PDF).** `pandoc` has
+  shipped in the base since v1.0.0 but as a front-end only — with no PDF
+  back-end installed, `studio_export_pdf` / `pandoc -o out.pdf` failed with
+  "xelatex not found". The base now installs `typst`, a single ~30 MB static
+  Rust binary (no LaTeX), used via `pandoc --pdf-engine=typst`. Chosen over a
+  ~600 MB TeX Live install; a fuller TeX Live remains the higher-fidelity
+  fallback for anyone needing LaTeX-exact output (install on demand). Also adds
+  `xz-utils` to the apt layer (typst ships a `.tar.xz` asset that `tar` needs
+  `xz` to extract). Installed with the standard `latest` GitHub-release idiom;
+  pin with `--build-arg TYPST_VERSION=vX.Y.Z`. This lands in `base-<hash>`
+  (Dockerfile.base changed). Supersedes the previously-planned
+  `:latest-studio-tex` variant — typst is small enough to ship in BASE, so no
+  separate TeX variant is needed. See `pi-devbox-roadmap`.
+
+---
+
 ## v1.3.0 — 2026-07-02
 
 Minor release. Headline: **shared/external MemPalace** — the `mempalace.ts`

Dockerfile.base

@@ -14,7 +14,7 @@
 # content-addressed over this file, so any byte change invalidates the
 # cache. Recommended cadence: once per release for security updates.
 #
-# BASE_REBUILD_DATE: 2026-06-09 (v1.0.0 — decoupled from opencode-devbox)
+# BASE_REBUILD_DATE: 2026-07-11 (Unreleased — typst PDF engine + xz-utils)
 #
 # ── Lineage note ─────────────────────────────────────────────────────
 # Adapted from opencode-devbox/Dockerfile.base (commit before v1.16.2).
@@ -46,7 +46,14 @@ ENV DEBIAN_FRONTEND=noninteractive
 # Additions vs the upstream opencode-devbox base (2026-06-09):
 #   pandoc       — Markdown↔HTML/PDF/etc. conversion. Required by pi-studio
 #                  preview/export pipelines and broadly useful for any
-#                  agent-driven document workflow. ~200 MB.
+#                  agent-driven document workflow. ~200 MB. NOTE: pandoc is
+#                  only the front-end — PDF output needs a back-end engine.
+#                  We ship `typst` (installed further down) as the
+#                  lightweight default engine (`pandoc --pdf-engine=typst`)
+#                  instead of a ~600 MB TeX Live install.
+#   xz-utils     — `xz` decompressor. tar shells out to it for `.tar.xz`
+#                  assets (typst ships .tar.xz). ~0.5 MB. Also generally
+#                  useful for extracting xz-compressed archives.
 #   graphviz     — `dot` rendering for many diagram tools. ~10 MB.
 #                  See the bundled `dot-watch` helper for live .dot -> PNG
 #                  re-render (handy with pi-studio's image preview).
@@ -95,6 +102,7 @@ RUN apt-get update && \
     python3-pip \
     python3-venv \
     pandoc \
+    xz-utils \
     graphviz \
     imagemagick \
     socat \
@@ -444,6 +452,32 @@ RUN ARCH=$(case "${TARGETARCH}" in amd64) echo "x86_64" ;; arm64) echo "aarch64"
     chmod +x /usr/local/bin/tldr && \
     tldr --version
 
+# ── typst — lightweight PDF engine for pandoc (Markdown→PDF) ─────────
+# pandoc (apt-installed above) is only a front-end; rendering PDF needs a
+# back-end engine. Rather than a ~600 MB TeX Live install, we ship typst:
+# a single ~30 MB static Rust binary with no LaTeX dependency. pi-studio's
+# PDF export (studio_export_pdf) and pandoc invocations use it via
+# `pandoc --pdf-engine=typst`. A fuller TeX Live remains the higher-
+# fidelity fallback for anyone who needs LaTeX-exact output (not shipped
+# here — install on demand or in a future variant).
+#
+# Follows the `latest` GitHub-release convention (like tealdeer/uv/bat).
+# typst ships a `.tar.xz` asset (hence xz-utils in the apt layer above)
+# that extracts to typst-<arch>-unknown-linux-musl/typst. Pin a specific
+# tag with --build-arg TYPST_VERSION=vX.Y.Z.
+ARG TYPST_VERSION=latest
+RUN ARCH=$(case "${TARGETARCH}" in amd64) echo "x86_64" ;; arm64) echo "aarch64" ;; *) echo "x86_64" ;; esac) && \
+    V="${TYPST_VERSION}" && \
+    if [ "$V" = "latest" ]; then \
+      V=$(curl -sI --retry 5 --retry-delay 5 --retry-all-errors "https://github.com/typst/typst/releases/latest" | awk 'tolower($1)=="location:" { sub(/\r$/,"",$2); n=split($2,a,"/"); print a[n] }'); \
+    fi && \
+    V="${V#v}" && [ -n "$V" ] && \
+    echo "Installing typst ${V}" && \
+    curl -fsSL --retry 5 --retry-delay 5 --retry-all-errors "https://github.com/typst/typst/releases/download/v${V}/typst-${ARCH}-unknown-linux-musl.tar.xz" | tar -xJ -C /tmp && \
+    install /tmp/typst-${ARCH}-unknown-linux-musl/typst /usr/local/bin/typst && \
+    rm -rf /tmp/typst-${ARCH}-unknown-linux-musl && \
+    typst --version
+
 # ── yq (mikefarah) — YAML processor, jq's companion for YAML ─────────
 # Installed as the mikefarah Go binary — NOT Debian's `yq` apt package, which
 # is the unrelated Python kislyuk/yq (a jq wrapper with different syntax and

README.md

@@ -149,12 +149,10 @@ Currently published:
 
 Planned for an upcoming minor release:
 
-- **PDF export from Studio/pandoc** (a future minor release). Engine still to be decided.
-  A lightweight engine is preferred over a full TeX install:
-  - `typst` — single static binary (~30 MB), `pandoc --pdf-engine=typst`; light
-    enough it could ship in the base image (no separate `-tex` variant needed).
-  - `joakimp/pi-devbox:latest-studio-tex` — `-studio` plus `texlive-xetex`
-    (~600 MB on top of `-studio`); highest fidelity, kept as the fallback.
+- *(shipped in Unreleased/base)* **PDF export from Studio/pandoc** now works:
+  the base image ships **`typst`** as the PDF engine (`pandoc --pdf-engine=typst`),
+  a single ~30 MB static binary — no separate `-tex` variant needed.
+  `texlive-xetex` stays the higher-fidelity fallback (install on demand).
 
 ## Using pi-studio (`-studio` variant)
 
@@ -289,11 +287,10 @@ Assuming the compose file publishes `127.0.0.1:8765:8765` (see method B):
 > until step 2 runs. If the browser can't connect, verify Studio is up
 > (`/studio --status`) and the bridge is running (`ps aux | grep socat`).
 
-> PDF export (`/studio-pdf`, `studio_export_pdf`) needs a PDF engine, which is
-> **not** in `-studio` (pandoc is present but has no engine, so export fails
-> with `xelatex not found`). Planned for a future release — likely a lightweight
-> engine such as `typst`, with `texlive-xetex` as the heavier fallback. HTML export,
-> KaTeX, Mermaid, and all REPL features work without it.
+> 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.
 
 ### Graphviz diagrams in Studio: `dot-watch`
 

scripts/smoke-test.sh

@@ -6,6 +6,7 @@
 # Verifies:
 #   - pi binary present and (if EXPECTED_PI_VERSION set) matches CI's resolved version
 #   - new v1.0.0 base additions (pandoc, graphviz, imagemagick, yq, tealdeer)
+#   - typst PDF engine for pandoc (Unreleased) — `pandoc --pdf-engine=typst`
 #   - non-modal editors nano + micro (alongside nvim)
 #   - tmux 0-indexing baked in /etc/tmux.conf (required for pi-studio variants)
 #   - pi-toolkit cloned at /opt/pi-toolkit
@@ -78,6 +79,8 @@ run "micro"           "micro --version"
 run "mempalace-mcp"   "mempalace-mcp --help"
 # v1.0.0 base additions — verify presence and basic functionality.
 run "pandoc"          "pandoc --version"
+run "typst"           "typst --version"
+run "pandoc+typst PDF engine" "printf '# hi\n' | pandoc --pdf-engine=typst -o /tmp/_smoke.pdf - && test -s /tmp/_smoke.pdf; rm -f /tmp/_smoke.pdf"
 run "graphviz (dot)"  "dot -V"
 run "imagemagick"     "magick --version"
 run "yq (mikefarah v4)" "yq --version | grep -qE 'mikefarah.*version v4'"