IanMayo · Jul 4, 2026 · Jul 4, 2026 · Jul 4, 2026 · Jul 4, 2026
diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
@@ -9,6 +9,7 @@ on:
 #   /                  → static welcome page (web/index.html)
 #   /slides/           → reveal.js findings deck (web/slides/)
 #   /playground/       → the Vite IDE app (built with a matching base path)
+#   /jupyterlite/      → JupyterLite in-browser demo (jupyter lite build)
 #   /sample-package/   → lesson 8's self-hosted Data Package (kept at root
 #                        so the URL hard-coded in lesson 8 stays valid)
 # PR previews (see pr-preview.yml) live under `/pr-preview/pr-N/` of the
@@ -59,7 +60,28 @@ jobs:
           VITE_BASE_PATH: /tabular-data-playground/playground/
         run: pnpm run build
 
-      - name: Assemble published site (welcome + slides + IDE + sample-package)
+      - name: Set up Python for JupyterLite build
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install JupyterLite build dependencies
+        working-directory: ${{ github.workspace }}
+        run: pip install -r jupyterlite/requirements.txt
+
+      - name: Build JupyterLite demo (served under /jupyterlite/)
+        working-directory: ${{ github.workspace }}/jupyterlite
+        run: |
+          jupyter lite build \
+            --output-dir _output \
+            --base-url /tabular-data-playground/jupyterlite/
+
+      - name: Verify JupyterLite build produced output
+        working-directory: ${{ github.workspace }}/jupyterlite
+        run: |
+          test -d _output && test -n "$(ls -A _output)"
+
+      - name: Assemble published site (welcome + slides + IDE + jupyterlite + sample-package)
         working-directory: ${{ github.workspace }}
         run: |
           set -e
@@ -70,6 +92,9 @@ jobs:
           # IDE under /playground/
           mkdir -p _site/playground
           cp -r app/dist/. _site/playground/
+          # JupyterLite demo under /jupyterlite/
+          mkdir -p _site/jupyterlite
+          cp -r jupyterlite/_output/. _site/jupyterlite/
           # Keep the lesson-8 sample package at the gh-pages root
           if [ -d _site/playground/sample-package ]; then
             rm -rf _site/sample-package

diff --git a/.github/workflows/pr-preview.yml b/.github/workflows/pr-preview.yml
@@ -6,6 +6,7 @@ name: PR Preview to GitHub Pages
 #   /pr-preview/pr-<N>/             → welcome page (web/index.html)
 #   /pr-preview/pr-<N>/slides/      → reveal.js findings deck
 #   /pr-preview/pr-<N>/playground/  → the Vite IDE (PR-scoped base path)
+#   /pr-preview/pr-<N>/jupyterlite/ → JupyterLite demo (PR-scoped base path)
 #   /pr-preview/pr-<N>/sample-package/ → lesson 8's package, kept at the
 #                                        preview root to mirror production
 # A single sticky comment (idempotent via the marker below) links to
@@ -62,14 +63,36 @@ jobs:
           VITE_BASE_PATH: /tabular-data-playground/pr-preview/pr-${{ github.event.pull_request.number }}/playground/
         run: pnpm run build
 
-      - name: Assemble preview site (welcome + slides + IDE + sample-package)
+      - name: Set up Python for JupyterLite build
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      - name: Install JupyterLite build dependencies
+        run: pip install -r jupyterlite/requirements.txt
+
+      - name: Build JupyterLite demo with PR-scoped base path
+        working-directory: jupyterlite
+        run: |
+          jupyter lite build \
+            --output-dir _output \
+            --base-url /tabular-data-playground/pr-preview/pr-${{ github.event.pull_request.number }}/jupyterlite/
+
+      - name: Verify JupyterLite build produced output
+        working-directory: jupyterlite
+        run: |
+          test -d _output && test -n "$(ls -A _output)"
+
+      - name: Assemble preview site (welcome + slides + IDE + jupyterlite + sample-package)
         run: |
           set -e
           rm -rf _site
           mkdir -p _site
           cp -r web/. _site/
           mkdir -p _site/playground
           cp -r app/dist/. _site/playground/
+          mkdir -p _site/jupyterlite
+          cp -r jupyterlite/_output/. _site/jupyterlite/
           if [ -d _site/playground/sample-package ]; then
             rm -rf _site/sample-package
             mv _site/playground/sample-package _site/sample-package
@@ -103,6 +126,7 @@ jobs:
               `- Welcome page: ${base}`,
               `- Findings slides: ${base}slides/`,
               `- IDE: ${base}playground/`,
+              `- JupyterLite demo: ${base}jupyterlite/`,
               '',
               `Built from \`${sha}\`. Updates on every push to this PR; removed when the PR closes.`,
             ].join('\n');

diff --git a/.gitignore b/.gitignore
@@ -145,3 +145,4 @@ vite.config.ts.timestamp-*
 # Claude Code local/user-specific artifacts (skills under .claude/skills/ are tracked)
 .claude/settings.local.json
 .claude/.credentials.json
+.jupyterlite.doit.db
diff --git a/.specify/memory/constitution.md b/.specify/memory/constitution.md
@@ -1,6 +1,37 @@
 <!--
 SYNC IMPACT REPORT
-Version change: 2.0.0 → 2.1.0
+Version change: 2.1.0 → 2.2.0
+Bump rationale: Technology Constraints materially expanded (MINOR) — a new
+"JupyterLite demo" bullet added to record the JupyterLite-based in-browser
+demo sub-site (`jupyterlite/`) and its independent pin set. This is a new
+infrastructural dependency (build-time `jupyter lite build` step + its own
+`requirements.txt`), which per the section's own rule is an amendment
+rather than a plain PR. No principle changed; no Definition of Done change.
+Modified principles: none.
+Added sections: none (Technology Constraints expanded with new bullet).
+Removed sections: none.
+Templates requiring updates:
+  - .specify/templates/plan-template.md — no edit required.
+  - .specify/templates/spec-template.md — no edit required.
+  - .specify/templates/tasks-template.md — no edit required.
+  - .specify/templates/checklist-template.md — no edit required.
+Companion edits in same commit:
+  - README.md — JupyterLite/kernel pins recorded in Pinned versions table.
+  - docs/limitations.md — JupyterLite demo sharp edges enumerated.
+  - jupyterlite/ — new demo source directory.
+  - .github/workflows/deploy.yml — additive JupyterLite build step.
+  - .github/workflows/pr-preview.yml — additive JupyterLite build step.
+  - web/index.html — link to /jupyterlite/ demo added.
+
+Previous amendment (2.0.0 → 2.1.0): Technology Constraints "Python runtime"
+slot expanded to admit `livemark` (lesson 9 Livemark capstone).
+Previous amendment (1.0.0 → 2.0.0): Principle VI redefined from "Pin and
+Freeze" to "Pin Versions, Iterate Forward".
+Follow-up TODOs: None.
+-->
+
+<!--
+PREVIOUS SYNC IMPACT REPORT (2.0.0 → 2.1.0)
 Bump rationale: Technology Constraints materially expanded (MINOR) — the
 "Python runtime" slot now admits `livemark`, the Frictionless publishing
 tool used by lesson 9 (Publish with Livemark). It is pinned and installed
@@ -170,6 +201,13 @@ The v1 stack is fixed by the spec and is part of the constitutional surface
   CI smoke-tests Chromium only.
 - **Accessibility**: best-effort — keyboard-navigable, semantic HTML, no
   formal WCAG conformance commitment (decision #15).
+- **JupyterLite demo**: a self-contained in-browser demo sub-site at
+  `/jupyterlite/` built by `jupyter lite build` (build-time Python step).
+  Toolchain pins live in `jupyterlite/requirements.txt`; they are
+  **independent** of the frozen playground's Pyodide `0.27.7` pin.
+  The demo is published additively alongside `/playground/` and is
+  online-only by design (Pyodide/wheels fetched from CDN at runtime).
+  Sharp edges in `docs/limitations.md`.
 
 Substitutions within these slots (e.g. `dockview` instead of `react-mosaic`)
 are permitted and not amendments. Adding a new infrastructural dependency,
@@ -238,4 +276,4 @@ Complexity Tracking section before `/speckit-tasks` runs.
 the constitution and the codebase continue to evolve while the project
 is in its pre-production research phase.
 
-**Version**: 2.1.0 | **Ratified**: 2026-05-08 | **Last Amended**: 2026-06-10
+**Version**: 2.2.0 | **Ratified**: 2026-05-08 | **Last Amended**: 2026-07-04
diff --git a/README.md b/README.md
@@ -91,6 +91,10 @@ the lessons in `content/lessons/` were authored against.
 | Table Schema JSON Schema | snapshot 2026-05-09 | Bundled from `https://specs.frictionlessdata.io/schemas/table-schema.json` to `app/src/editor/schemas/table-schema.json`. |
 | Table Dialect JSON Schema | snapshot 2026-05-09 (v2) | Bundled from `https://datapackage.org/profiles/2.0/tabledialect.json` to `app/src/editor/schemas/table-dialect.json` (`specs.frictionlessdata.io` returns 404 for dialect; `datapackage.org` is the canonical home). |
 | reveal.js (findings slides) | `5.1.0` | Loaded by `web/slides/index.html` from `https://cdn.jsdelivr.net/npm/reveal.js@5.1.0/` — the URL is the pin. |
+| JupyterLite core (demo) | `0.8.0` | `jupyterlite/requirements.txt`; **independent** of the frozen playground's Pyodide pin. |
+| JupyterLite Pyodide kernel (demo) | `0.8.1` | `jupyterlite/requirements.txt`; bundled Pyodide version determined by the kernel release. |
+| jupyter-server (demo build) | `2.20.0` | `jupyterlite/requirements.txt`; required by `jupyterlite-core` to index and serve custom content files. |
+| matplotlib (demo, in-browser) | runtime (Pyodide wheel) | Installed in-browser via `%pip install matplotlib` in the demo notebook; version resolved from the JupyterLite Pyodide kernel's bundled wheel index. |
 
 The editor still attempts a runtime fetch of the canonical schemas
 on mount with a short timeout and uses the live copy if it

diff --git a/docs/limitations.md b/docs/limitations.md
@@ -480,3 +480,38 @@ double-Tab listing. xterm.js's default `bellStyle` is silent
 This is a deliberate choice (classroom/demo context); enabling
 a bell sound would require shipping an audio asset and is out
 of scope.
+
+## JupyterLite demo findings
+
+### Demo is online-only (no offline / air-gapped path)
+
+The JupyterLite demo at `/jupyterlite/` relies on CDN-hosted
+Pyodide and wheel packages fetched at runtime by the
+JupyterLite Pyodide kernel. A visitor without internet access
+will see the notebook interface but cells that trigger
+`%pip install` or import a non-bundled package will fail
+silently or with a network error. There is no offline fallback
+and no service-worker caching of the wheel files. This is
+deliberate — bundling the full Pyodide + matplotlib wheel set
+into the repo would add tens of MB of binary content.
+
+### Cold-load wheel weight (first uncached visit)
+
+The first uncached visit fetches the Pyodide runtime (~10 MB
+compressed) plus the matplotlib wheel and its transitive
+dependencies from the Pyodide CDN. Subsequent visits are
+browser-cached. There is no hard latency budget; on a slow
+connection the first `Run All` on the demo notebook can take
+tens of seconds before the figure appears. This is an
+accepted trade-off of the CDN-delivery model.
+
+### Separate pin set — independent of the frozen playground
+
+The demo (`jupyterlite/requirements.txt`) carries its own
+`jupyterlite-core` and `jupyterlite-pyodide-kernel` pins,
+decoupled from the frozen playground's Pyodide `0.27.7`.
+Bumping either set does not affect the other, but they must
+be kept consistent within each context: the playground's
+Frictionless lessons were authored against Pyodide `0.27.7`
+and bumping that pin risks lesson regression. The demo pins
+are independent and can be bumped separately.
diff --git a/jupyterlite/.gitignore b/jupyterlite/.gitignore
@@ -0,0 +1,4 @@
+_output/
+__pycache__/
+*.pyc
+.jupyterlite.doit.db
diff --git a/jupyterlite/README.md b/jupyterlite/README.md
@@ -0,0 +1,82 @@
+# JupyterLite Demo
+
+A self-contained in-browser JupyterLite site that ships one example notebook
+(`demo.ipynb`) loading a sample CSV and rendering matplotlib figures inline.
+Everything runs in the browser via Pyodide — no server, no account required.
+
+Published at `/jupyterlite/` on the GitHub Pages site alongside the frozen
+playground (`/playground/`). The two surfaces are built by independent
+toolchains and share no pins.
+
+## Requirements
+
+Python 3.11+ (build-time only). The notebook runs against the JupyterLite
+Pyodide kernel's bundled Python in-browser; no local Python is used at
+runtime.
+
+## Single reproducible build command
+
+From the **`jupyterlite/` directory**:
+
+```bash
+# From the repository root:
+pip install -r jupyterlite/requirements.txt
+cd jupyterlite
+jupyter lite build --output-dir _output
+```
+
+The output is written to `jupyterlite/_output/`. Serve locally with:
+
+```bash
+# From jupyterlite/:
+jupyter lite serve --output-dir _output
+```
+
+Then open `http://localhost:8000` (or the URL printed in the terminal),
+navigate to `demo.ipynb`, and run all cells — a matplotlib figure should
+render inline.
+
+## Base URL parameterisation
+
+For deployment under a sub-path, pass `--base-url` to the build command
+(run from the `jupyterlite/` directory):
+
+```bash
+jupyter lite build \
+  --output-dir _output \
+  --base-url /tabular-data-playground/jupyterlite/
+```
+
+The CI workflows set the correct base URL for production
+(`/tabular-data-playground/jupyterlite/`) and for PR previews
+(`/tabular-data-playground/pr-preview/pr-<N>/jupyterlite/`).
+
+## Pinned toolchain
+
+Versions are pinned in `requirements.txt`. Do **not** bump them without
+verifying the demo notebook still renders correctly, and update the
+"Pinned versions" table in `README.md` at the repository root accordingly.
+
+| Package | Version |
+|---------|---------|
+| jupyterlite-core | 0.8.0 |
+| jupyterlite-pyodide-kernel | 0.8.1 |
+| jupyter-server | 2.20.0 |
+
+## Directory layout
+
+```
+jupyterlite/
+├── requirements.txt         # Build-time Python deps (pinned)
+├── jupyter_lite_config.json # Build configuration
+├── jupyter-lite.json        # Runtime configuration (kernel, disabled features)
+├── README.md                # This file
+├── .gitignore               # Excludes _output/ from version control
+└── files/                   # Content shipped into the JupyterLite site
+    ├── demo.ipynb           # Example notebook
+    └── data/
+        └── sample.csv       # Generic sample dataset
+```
+
+The `_output/` directory is the build artefact and is **not committed** to
+version control (see `.gitignore`).
diff --git a/jupyterlite/files/data/sample.csv b/jupyterlite/files/data/sample.csv
@@ -0,0 +1,31 @@
+city,country,year,population,gdp_per_capita_usd,life_expectancy
+London,UK,2022,9648110,46510,81.2
+Berlin,Germany,2022,3677472,50210,81.3
+Paris,France,2022,2161000,44020,82.5
+Madrid,Spain,2022,3305408,30120,83.4
+Rome,Italy,2022,2873494,34060,83.6
+Amsterdam,Netherlands,2022,921402,57800,82.1
+Brussels,Belgium,2022,1222637,47300,81.5
+Vienna,Austria,2022,1897491,53120,81.7
+Stockholm,Sweden,2022,975551,55300,82.8
+Oslo,Norway,2022,698660,89140,83.2
+Copenhagen,Denmark,2022,794128,67440,81.6
+Helsinki,Finland,2022,658864,50520,82.0
+Dublin,Ireland,2022,592713,99260,82.3
+Warsaw,Poland,2022,1794166,18820,78.5
+Prague,Czech Republic,2022,1335084,26630,79.1
+Budapest,Hungary,2022,1752704,18400,76.7
+Bucharest,Romania,2022,2161347,15280,76.0
+Sofia,Bulgaria,2022,1307439,12500,75.1
+Zagreb,Croatia,2022,806341,17760,78.2
+Athens,Greece,2022,664046,20110,82.2
+Lisbon,Portugal,2022,545245,24640,82.1
+Riga,Latvia,2022,605802,21060,75.8
+Vilnius,Lithuania,2022,580020,23480,76.4
+Tallinn,Estonia,2022,437619,26840,78.0
+Ljubljana,Slovenia,2022,295504,28930,81.4
+Bratislava,Slovakia,2022,477174,21300,77.5
+Nicosia,Cyprus,2022,269700,29330,81.0
+Valletta,Malta,2022,5828,31640,82.7
+Luxembourg City,Luxembourg,2022,132780,119720,82.3
+Reykjavik,Iceland,2022,131136,73960,83.1