diff --git a/assets/templates/workbook/workbook-base.html b/assets/templates/workbook/workbook-base.html
index 9913e6c..035d8e6 100644
--- a/assets/templates/workbook/workbook-base.html
+++ b/assets/templates/workbook/workbook-base.html
@@ -167,6 +167,14 @@
 }
 .wb-callout strong { color: var(--wb-accent); font-weight: 600; }
 
+/* ---- Component: lede (lead paragraph that opens a step) ---- */
+.wb-lede { font-size: 1.18rem; line-height: 1.6; color: var(--wb-sub); margin: 0 0 var(--wb-sp-4); max-width: var(--wb-measure); }
+
+/* ---- Component: quote (pull-quote + attribution) ---- */
+.wb-quote { margin: var(--wb-sp-5) 0; padding-left: var(--wb-sp-5); border-left: 3px solid var(--wb-accent); }
+.wb-quote blockquote { margin: 0; font-style: italic; font-size: 1.15rem; line-height: 1.5; color: var(--wb-text); }
+.wb-quote cite { display: block; margin-top: var(--wb-sp-2); font-style: normal; font-size: .9rem; color: var(--wb-sub); }
+
 /* ---- Component: accordion ---- */
 .wb-accordion { border: var(--wb-border); border-radius: var(--wb-r-md); background: var(--wb-surface); box-shadow: var(--wb-shadow-sm); margin: var(--wb-sp-5) 0; overflow: hidden; }
 .wb-accordion__trigger {
@@ -256,6 +264,15 @@
 .wb-code pre .diff-add { display: block; background: color-mix(in srgb, var(--wb-good) 22%, transparent); }
 .wb-code pre .diff-del { display: block; background: color-mix(in srgb, var(--wb-bad) 18%, transparent); text-decoration: line-through; text-decoration-color: color-mix(in srgb, var(--wb-bad) 60%, transparent); }
 
+/* ---- Code syntax highlighting (dependency-free, fixed palette on the dark code surface).
+   Convention: wrap tokens by role — kw=keyword, str=string, num=number, fn=function/type,
+   cmt=comment. Fixed hues (not brand tokens) for legibility on the code background. ---- */
+.wb-code pre .kw  { color: #c79bf0; }   /* keyword */
+.wb-code pre .str { color: #9ed7a8; }   /* string */
+.wb-code pre .num { color: #e0a87a; }   /* number */
+.wb-code pre .fn  { color: #7fc7e8; }   /* function / type */
+.wb-code pre .cmt { color: #8a8a93; font-style: italic; }   /* comment */
+
 /* ---- Component: bar chart (precomputed SVG coords; highlight the salient datum) ---- */
 .wb-chart svg .bar { fill: var(--wb-line); }
 .wb-chart svg .bar.is-peak { fill: var(--wb-accent); }   /* recolor the one datum that matters */
@@ -270,6 +287,14 @@
 .wb-knob input[type="range"] { flex: 1; accent-color: var(--wb-accent); }
 .wb-knob__val { font-family: var(--wb-font-mono); font-size: 13px; color: var(--wb-accent); min-width: 52px; text-align: right; }
 .wb-knob__preview { height: 14px; border-radius: 999px; background: var(--wb-accent); width: var(--knob, 50%); margin-top: var(--wb-sp-4); transition: width .12s ease; }
+/* Split variant: a full-width A-vs-B bar (e.g. P(1) vs P(0)). The value portion is
+   accent, the remainder accent-2; both driven by the same --knob var (no JS change). */
+.wb-knob__preview.is-split { width: 100%; transition: none;
+  background: linear-gradient(90deg, var(--wb-accent) 0 var(--knob, 50%), var(--wb-accent-2) var(--knob, 50%) 100%); }
+.wb-knob__legend { display: flex; gap: var(--wb-sp-4); margin-top: var(--wb-sp-2); font-size: .8rem; color: var(--wb-sub); }
+.wb-knob__legend span::before { content: ""; display: inline-block; width: 10px; height: 10px; border-radius: 3px; margin-right: 6px; vertical-align: middle; }
+.wb-knob__legend .lg-a::before { background: var(--wb-accent); }
+.wb-knob__legend .lg-b::before { background: var(--wb-accent-2); }
 @media (prefers-reduced-motion: reduce) { .wb-knob__preview { transition: none; } }
 .wb-knob__caption { font-size: .9rem; color: var(--wb-sub); margin-top: var(--wb-sp-3); }
 
@@ -328,11 +353,21 @@ <h1>{{course.title}}</h1>
         <div class="wb-eyebrow">{{module.title}}</div>
       </div>
       <h2>{{step.title}}</h2>
+
+      <!-- Component: lede (one-line framing that opens the step) -->
+      <p class="wb-lede">{{lede — the one sentence that frames this step}}</p>
+
       <p>{{step.body}} A key term like <span class="wb-term" data-term="ring">the ring</span> can be linked to the glossary below.</p>
 
       <!-- Component: statement / callout -->
       <div class="wb-callout"><strong>{{key word}}</strong> {{statement}}</div>
 
+      <!-- Component: quote (pull-quote + attribution) -->
+      <figure class="wb-quote">
+        <blockquote>{{memorable line}}</blockquote>
+        <cite>{{attribution — optional}}</cite>
+      </figure>
+
       <!-- Component: accordion -->
       <div class="wb-accordion">
         <button class="wb-accordion__trigger" aria-expanded="false" aria-controls="acc-1-panel" id="acc-1-trigger">{{summary}}</button>
@@ -349,10 +384,10 @@ <h2>{{step.title}}</h2>
         <div class="wb-tabs__panel" id="panel-1b" role="tabpanel" aria-labelledby="tab-1b" hidden>{{panel B}}</div>
       </div>
 
-      <!-- Component: annotated code -->
+      <!-- Component: annotated code (wrap tokens by role: kw/str/num/fn/cmt — see skill) -->
       <div class="wb-code">
         <button class="wb-code__copy" type="button">Copy</button>
-        <pre><code>{{code}}</code></pre>
+        <pre><code><span class="kw">{{keyword}}</span> {{code}} <span class="cmt">{{# comment}}</span></code></pre>
         <ul class="wb-code__notes">
           <li>{{annotation}}</li>
         </ul>
@@ -415,6 +450,19 @@ <h2>{{step.title}}</h2>
         <p class="wb-knob__caption">{{what dragging this teaches}}</p>
       </div>
 
+      <!-- Component: parametric knob — SPLIT variant (use when the value is one side of an
+           A-vs-B split, e.g. P(1) vs P(0)). Add `is-split` to the preview + a legend. -->
+      <div class="wb-knob">
+        <div class="wb-knob__row">
+          <span class="wb-knob__label" id="knob-2-label">{{parameter}}</span>
+          <input type="range" id="knob-2" min="0" max="100" value="50" data-knob aria-labelledby="knob-2-label" aria-describedby="knob-2-val">
+          <span class="wb-knob__val" id="knob-2-val">50%</span>
+        </div>
+        <div class="wb-knob__preview is-split" id="knob-2-preview"></div>
+        <div class="wb-knob__legend"><span class="lg-a">{{outcome A — the value portion}}</span><span class="lg-b">{{outcome B — the remainder}}</span></div>
+        <p class="wb-knob__caption">{{what dragging this teaches — name both outcomes}}</p>
+      </div>
+
       <!-- Component: comparison table (mono uppercase th, good/bad cells) -->
       <table class="wb-table">
         <thead><tr><th>{{dimension}}</th><th>{{option A}}</th><th>{{option B}}</th></tr></thead>
diff --git a/commands/workbook-generate.md b/commands/workbook-generate.md
index 584b5cb..3a76d30 100644
--- a/commands/workbook-generate.md
+++ b/commands/workbook-generate.md
@@ -108,11 +108,14 @@ or by each `workbook-module-composer` subagent (fan-out). Apply the
 **content-shape -> component mapping** from the skill. Summary:
 
 - Course -> module **chapters** + a **table of contents** + course **progress**.
-- Each reading -> a run of steps in its module chapter; each `H2` -> a **step**.
+- Each reading -> a run of steps in its module chapter; each `H2` -> a **step**;
+  open a step with a one-line **lede** when it helps frame the section.
 - Tables -> **comparison diagram** / **tabs** / **chart** (by intent).
 - Ordered process lists -> **flow diagram** / stepper.
-- Fenced code -> **annotated code block**.
-- Load-bearing sentences -> **statement / callout**.
+- Fenced code -> **annotated code block** (highlight tokens by role: `kw`/`str`/`num`/`fn`/`cmt`).
+- Load-bearing sentence -> **statement / callout**; a memorable/authoritative line -> **quote**.
+- A value that's one side of a split (e.g. a probability, P(1) vs P(0)) -> a
+  **knob** with the `is-split` two-color bar so the viz matches the caption.
 - Optional depth -> **accordion**; parallel alternatives -> **tabs**.
 - End of each major section -> an optional **predict-and-reveal** self-check
   (think first, then reveal the answer — not a graded quiz); `quiz-*.md` ->
@@ -203,6 +206,22 @@ This is a quality pass on the *creative payload* only — the invariant frame
 3. **Suggest**: "Open in a browser to review; traverse the modules and complete
    a few checks. Answers reset on refresh (expected — persistence is deferred)."
 
+## Phase 6 — Validate the generated file
+
+Run the output validator on the file you just wrote:
+
+```
+python3 ${CLAUDE_PLUGIN_ROOT}/scripts/validate_workbook.py <output-path>
+```
+
+It checks the invariants the artifact must hold: **standalone** (no external
+`<script src>` / CDN), **in-memory only** (no `localStorage` / `sessionStorage`
+/ `indexedDB` / `postMessage`), **globally-unique element ids** (critical after
+a fan-out assembly), and warns on missing a11y landmarks or a missing
+`system-ui` font fallback. **Errors exit non-zero — fix them before reporting
+the workbook as done.** (If `${CLAUDE_PLUGIN_ROOT}` is unavailable, run it by its
+repo-relative path `scripts/validate_workbook.py`.)
+
 ## Overlay invocation (post-base-draft)
 
 After producing the base draft for this command (the generated workbook HTML
diff --git a/scripts/validate_workbook.py b/scripts/validate_workbook.py
new file mode 100644
index 0000000..f6565b2
--- /dev/null
+++ b/scripts/validate_workbook.py
@@ -0,0 +1,123 @@
+#!/usr/bin/env python3
+"""Validate a generated interactive workbook HTML against its invariants (DOJ-4839).
+
+This is an AUTHOR tool, not a plugin-repo CI gate — generated workbooks live in
+the *consumer* repo, so run it on demand against a produced file:
+
+    python3 scripts/validate_workbook.py path/to/workbook-<slug>.html [more.html ...]
+
+It enforces the contracts the `workbook-generate` command promises:
+
+  ERRORS (exit 1 — the artifact is broken or violates a hard rule):
+    - Standalone: no external `<script src=...>`, no CDN runtime refs.
+    - In-memory only (V1): no localStorage / sessionStorage / indexedDB / postMessage.
+    - Globally-unique element ids (invalid HTML + breaks anchors / aria / label `for`;
+      the per-module fan-out depends on `m{N}-` namespacing to avoid this).
+
+  WARNINGS (reported, do not fail):
+    - Accessibility landmarks present (>=1 role="region", a role="progressbar").
+    - A `system-ui` fallback alongside any Google Fonts <link>.
+
+Pure stdlib (re only) — same posture as scripts/ci/*.
+"""
+from __future__ import annotations
+
+import re
+import sys
+
+# CDN only counts as a *runtime dependency* when it's a resource tag's href/src
+# (link/script/img/iframe) — not a plain <a> link to an educational resource.
+CDN_RE = re.compile(
+    r"""<(?:link|script|img|iframe)\b[^>]*?\b(?:href|src)\s*=\s*["'](https?://[^"']*(?:cdn\.|unpkg\.com|jsdelivr\.net|cdnjs\.)[^"']*)""",
+    re.I,
+)
+SCRIPT_SRC_RE = re.compile(r"<script\b[^>]*\bsrc\s*=", re.I)
+SCRIPT_BLOCK_RE = re.compile(r"<script\b[^>]*>(.*?)</script>", re.I | re.S)
+CODE_BLOCK_RE = re.compile(r"<(pre|code)\b[^>]*>.*?</\1>", re.I | re.S)
+STATE_RE = re.compile(r"\b(localStorage|sessionStorage|indexedDB|postMessage)\b")
+ID_RE = re.compile(r'\sid\s*=\s*"([^"]+)"', re.I)
+ROLE_REGION_RE = re.compile(r'role\s*=\s*["\']?region["\']?', re.I)
+ROLE_PROGRESS_RE = re.compile(r'role\s*=\s*["\']?progressbar["\']?', re.I)
+GFONTS_RE = re.compile(r"fonts\.googleapis\.com", re.I)
+
+
+def validate(path: str) -> tuple[list[str], list[str]]:
+    errors: list[str] = []
+    warnings: list[str] = []
+    try:
+        with open(path, encoding="utf-8") as f:
+            html = f.read()
+    except OSError as e:
+        return ([f"{path}: cannot read - {e}"], [])
+
+    # --- Standalone ---
+    if SCRIPT_SRC_RE.search(html):
+        errors.append(f"{path}: external <script src=...> found (must be self-contained)")
+    cdn = {m.group(1) for m in CDN_RE.finditer(html)}
+    if cdn:
+        errors.append(f"{path}: CDN runtime reference(s): {', '.join(sorted(cdn))}")
+
+    # --- In-memory only (V1) — scan SCRIPT CONTENTS only, so prose/code that merely
+    #     *mentions* localStorage (e.g. a lesson about it) doesn't false-fail. ---
+    script_src = "\n".join(m.group(1) for m in SCRIPT_BLOCK_RE.finditer(html))
+    state_hits = sorted({m.group(1) for m in STATE_RE.finditer(script_src)})
+    if state_hits:
+        errors.append(
+            f"{path}: persistence/parent-comm API(s) used in script (V1 is in-memory only): "
+            + ", ".join(state_hits)
+        )
+
+    # --- Globally-unique ids — exclude <pre>/<code> so sample-code placeholder ids
+    #     inside lessons don't count as real document ids. ---
+    html_no_code = CODE_BLOCK_RE.sub("", html)
+    seen: dict[str, int] = {}
+    for m in ID_RE.finditer(html_no_code):
+        seen[m.group(1)] = seen.get(m.group(1), 0) + 1
+    dupes = {k: v for k, v in seen.items() if v > 1}
+    if dupes:
+        listed = ", ".join(f"{k} (×{v})" for k, v in sorted(dupes.items())[:10])
+        more = "" if len(dupes) <= 10 else f" (+{len(dupes) - 10} more)"
+        errors.append(f"{path}: duplicate element id(s): {listed}{more}")
+
+    # --- Warnings: a11y landmarks ---
+    if not ROLE_REGION_RE.search(html):
+        warnings.append(f'{path}: no role="region" landmarks found (steps should be regions)')
+    if not ROLE_PROGRESS_RE.search(html):
+        warnings.append(f'{path}: no role="progressbar" found (progress indicator expected)')
+
+    # --- Warnings: font fallback ---
+    if GFONTS_RE.search(html) and "system-ui" not in html:
+        warnings.append(f"{path}: Google Fonts <link> present but no system-ui fallback in the stack")
+
+    return (errors, warnings)
+
+
+def main(argv: list[str]) -> int:
+    paths = argv[1:]
+    if not paths:
+        print("usage: validate_workbook.py <workbook.html> [more.html ...]", file=sys.stderr)
+        return 2
+
+    total_err = 0
+    total_warn = 0
+    for path in paths:
+        errors, warnings = validate(path)
+        total_err += len(errors)
+        total_warn += len(warnings)
+        for e in errors:
+            print(f"ERROR  {e}")
+        for w in warnings:
+            print(f"WARN   {w}")
+        if not errors and not warnings:
+            print(f"OK     {path}: standalone, in-memory-only, unique ids, a11y landmarks present")
+        elif not errors:
+            print(f"OK     {path}: no errors ({len(warnings)} warning(s))")
+
+    print(
+        f"\nValidated {len(paths)} file(s): {total_err} error(s), {total_warn} warning(s)."
+    )
+    return 1 if total_err else 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main(sys.argv))
diff --git a/skills/workbook-generate/SKILL.md b/skills/workbook-generate/SKILL.md
index e9cc077..5d74471 100644
--- a/skills/workbook-generate/SKILL.md
+++ b/skills/workbook-generate/SKILL.md
@@ -105,6 +105,9 @@ preferences do.
 | Component | Purpose |
 |---|---|
 | **step / section** | A unit of the flow. Each `H2` of a reading is typically one step. |
+| **lede** | A one-line lead paragraph (`.wb-lede`) that frames a step before the body. Bigger, muted; sets up what the step is about. |
+| **statement / callout** | A bordered emphasis block for a load-bearing sentence; key words in `<strong>` render in the accent. |
+| **quote** | A pull-quote (`.wb-quote` `<blockquote>` + optional `<cite>`) for a memorable/authoritative line. |
 | **progress bar** | Course-level and per-module completion %. Updates as the learner advances. |
 | **completion event** | Fired (not persisted) when the learner reaches the end. A hook point for V2. |
 
@@ -136,7 +139,7 @@ preferences do.
 
 | Component | Purpose |
 |---|---|
-| **code block** | Syntax-styled code with a copy button (with a `file://` clipboard fallback) and optional margin annotations / line callouts. High value for a coding curriculum. |
+| **code block** | Syntax-styled code with a copy button (with a `file://` clipboard fallback) and optional margin annotations / line callouts. High value for a coding curriculum. **Syntax highlighting** is dependency-free: wrap tokens by role in `<span>`s — `kw` (keyword), `str` (string), `num` (number), `fn` (function/type), `cmt` (comment). Fixed legible hues on the dark code surface (not brand tokens). |
 | **code diff** | A before -> after variant of the code block: removed lines (`.diff-del`, struck through) and added lines (`.diff-add`) banded inline. Teaches *the change*, not just the result — the core move of teaching code. |
 
 ### Parametric knob (the reliable "felt" interaction)
@@ -144,6 +147,7 @@ preferences do.
 | Component | Purpose |
 |---|---|
 | **knob** | A slider whose value writes a CSS custom property (`--knob`) that a preview element consumes and a readout mirrors. Lets a learner *drag and watch the effect* — the felt interactivity of the reference site's simulations, delivered through a fixed, tested component rather than bespoke per-concept JS. In-memory only. |
+| **knob (split-bar)** | The `is-split` preview variant: a full-width **A-vs-B bar** where the value portion is the accent and the remainder is `--wb-accent-2`, with a 2-item legend. Use when the value is one side of a split (e.g. P(1) vs P(0)) so the bar matches a caption that names both outcomes. Same `--knob` wiring — no extra JS. |
 
 ### Course navigation