diff --git a/SKILLS/nc-dom-ser/references/fidelity-matrix.md b/SKILLS/nc-dom-ser/references/fidelity-matrix.md
index 359577d..e80f4e5 100644
--- a/SKILLS/nc-dom-ser/references/fidelity-matrix.md
+++ b/SKILLS/nc-dom-ser/references/fidelity-matrix.md
@@ -1,7 +1,10 @@
-# Page fidelity matrix
+# NoteCraft Format Fidelity Matrix
 
-Use this matrix to decide which boundaries and checks a change needs. It is a
-routing aid, not a replacement for the normative page model.
+**Complete reference for all supported content types, objects, and their representations in HTML and CommonMark/GFM formats.**
+
+## Quick Reference: Change Impact Guide
+
+Use this matrix to decide which boundaries and checks a change needs. It is a routing aid, not a replacement for the normative page model.
 
 | Change affects | Inspect | Minimum proof |
 |---|---|---|
@@ -15,11 +18,339 @@ routing aid, not a replacement for the normative page model.
 | Code view | source pane and file listing | visible file ownership and edit round trip |
 | Demo content | authored content and generated demo | `demo-check`, semantic parity, visual side-by-side |
 
-## Questions before editing
+---
+
+## Block-Level Content Types
+
+### Text Blocks
+
+| Type | HTML | CommonMark | Status | Notes |
+|------|------|-----------|--------|-------|
+| **Headings** |
+| Heading 1 | `<h1>text</h1>` | `# text` | ✓ Full parity | Six levels (h1-h6) supported |
+| Heading 2 | `<h2>text</h2>` | `## text` | ✓ Full parity | |
+| Heading 3 | `<h3>text</h3>` | `### text` | ✓ Full parity | |
+| Heading 4 | `<h4>text</h4>` | `#### text` | ✓ Full parity | |
+| Heading 5 | `<h5>text</h5>` | `##### text` | ✓ Full parity | |
+| Heading 6 | `<h6>text</h6>` | `###### text` | ✓ Full parity | |
+| **Body Text** |
+| Paragraph | `<p>text</p>` | Line with blank line separator | ✓ Full parity | Standard block; multiple paras separated by blank lines |
+| Blockquote | `<blockquote><p>text</p></blockquote>` | `> text` (can nest) | ✓ Full parity | Container for quoted content; supports nesting |
+| **Code Blocks** |
+| Code (fenced) | `<pre><code class="language-xyz">` | ` ```xyz ` | ✓ Full parity | Language tag for syntax highlighting |
+| Code (indented) | `<pre><code>` | 4-space indent | ✓ Full parity | Legacy format, supported in both |
+| **Structural** |
+| Horizontal rule | `<hr>` | `---` or `***` | ✓ Full parity | Visual page divider |
+
+### Lists
+
+| Type | HTML | CommonMark | Status | Notes |
+|------|------|-----------|--------|-------|
+| **Unordered List** |
+| Bullet item | `<ul><li>item</li></ul>` | `- item` or `* item` | ✓ Full parity | Single-level or nested |
+| Nested bullets | `<ul><li>item<ul><li>nested</li></ul></li></ul>` | Indented `  - nested` | ✓ Full parity | Supports arbitrary depth |
+| **Ordered List** |
+| Numbered item | `<ol><li>item</li></ol>` | `1. item` | ✓ Full parity | Auto-numbered in output |
+| Nested numbers | `<ol><li>item<ol><li>nested</li></ol></li></ol>` | Indented `  1. nested` | ✓ Full parity | Mixed nesting allowed |
+| **Task List** |
+| Unchecked task | `<li><input type="checkbox"> Task</li>` | `- [ ] Task` | ✓ Full parity | GFM extension |
+| Checked task | `<li><input type="checkbox" checked> Done</li>` | `- [x] Done` | ✓ Full parity | Checked state preserved |
+
+### Tables
+
+| Type | HTML | CommonMark | Status | Notes |
+|------|------|-----------|--------|-------|
+| **Table Structure** |
+| Header row | `<thead><tr><th>header</th></tr></thead>` | First row + separator row | ✓ Full parity | GFM table format |
+| Data row | `<tbody><tr><td>cell</td></tr></tbody>` | `\| cell \|` | ✓ Full parity | Multiple rows supported |
+| Table cell | `<td>content</td>` | Pipe-delimited | ✓ Full parity | Can contain inline formatting |
+| Cell alignment | `<td align="left/center/right">` | `:---`, `:---:`, `---:` | ✓ Full parity | Left/center/right justify |
+
+---
+
+## Inline Formatting & Emphasis
+
+| Format | HTML | CommonMark | Status | Notes |
+|--------|------|-----------|--------|-------|
+| **Emphasis** |
+| Bold | `<strong>text</strong>` | `**text**` or `__text__` | ✓ Full parity | Strong emphasis |
+| Italic | `<em>text</em>` | `*text*` or `_text_` | ✓ Full parity | Emphasis |
+| Bold + Italic | `<strong><em>text</em></strong>` | `***text***` or `___text___` | ✓ Full parity | Combined |
+| Strikethrough | `<s>text</s>` or `<del>text</del>` | `~~text~~` | ✓ Full parity | GFM strikethrough |
+| Subscript | `<sub>text</sub>` | `~text~` (proposed) | ⚠ Limited | Not standard GFM; HTML-primary |
+| Superscript | `<sup>text</sup>` | `^text^` (proposed) | ⚠ Limited | Not standard GFM; HTML-primary |
+| **Links & References** |
+| Hyperlink | `<a href="url">text</a>` | `[text](url)` | ✓ Full parity | External or internal |
+| Link with title | `<a href="url" title="Title">text</a>` | `[text](url "Title")` | ✓ Full parity | Tooltip on hover |
+| Reference link | `<a href="url">text</a>` | `[text][ref]\n[ref]: url` | ✓ Full parity | Link ref defined elsewhere |
+| **Code & Math** |
+| Inline code | `<code>text</code>` | `` `text` `` | ✓ Full parity | Monospace; no formatting inside |
+| Code (escaped backticks) | `<code>\`text\`</code>` | ``` `` `text` `` ``` | ✓ Full parity | Literal backticks in code |
+| Math inline | `<span class="math">$...$</span>` | `$...$` | ✓ Full parity | KaTeX/TeX syntax; wrapped |
+| **Images** |
+| Inline image | `<img src="path" alt="text">` | `![alt](path)` | ✓ Full parity | Inline media reference |
+| Image with title | `<img src="path" alt="alt" title="Title">` | `![alt](path "Title")` | ✓ Full parity | Tooltip shown on hover |
+| **Special Characters** |
+| Hard line break | `<br>` | Two spaces + newline, or `\` | ✓ Full parity | Preserved in both formats |
+| Soft break | Newline | Newline | ✓ Full parity | Treated as space in output |
+
+---
+
+## Math & Science Content
+
+| Type | HTML | CommonMark | Storage | Rendering |
+|------|------|-----------|---------|-----------|
+| **Inline Math** |
+| Math expression | `<span class="math">$E=mc^2$</span>` | `$E=mc^2$` | LaTeX/KaTeX source | MathJax render on display |
+| Subscripts | `$CO_2$` | `$CO_2$` | LaTeX | Rendered in display |
+| Superscripts | `$E=mc^2$` | `$E=mc^2$` | LaTeX | Rendered in display |
+| **Block Math** |
+| Display equation | `<div class="math">$$E=mc^2$$</div>` | `$$E=mc^2$$` | LaTeX/KaTeX source | MathJax display mode |
+| Multiline equation | `<div class="math">$$...align...$$</div>` | ` ```math ... ``` ` or `$$...$$` | LaTeX | Display-mode rendering |
+| **Chemical Notation** |
+| Chemical formula | `<span class="chem">H₂O</span>` | `H~2~O` or `H₂O` | Unicode/HTML | Standard subscript format |
+
+---
+
+## Diagrams & Visualizations
+
+### Mermaid Diagrams
+
+| Diagram Type | HTML | CommonMark | Storage | Rendering |
+|--------------|------|-----------|---------|-----------|
+| **Flowcharts** |
+| Flowchart | `<pre class="mermaid">graph LR...</pre>` | ` ```mermaid graph LR... ``` ` | Mermaid source | Rendered via mermaid.js |
+| **Sequence** |
+| Sequence diagram | `<pre class="mermaid">sequenceDiagram...</pre>` | ` ```mermaid sequenceDiagram... ``` ` | Mermaid source | Sequence chart output |
+| **Structural** |
+| Class diagram | `<pre class="mermaid">classDiagram...</pre>` | ` ```mermaid classDiagram... ``` ` | Mermaid source | OOP structure |
+| Entity-relation | `<pre class="mermaid">erDiagram...</pre>` | ` ```mermaid erDiagram... ``` ` | Mermaid source | Database schema |
+| State machine | `<pre class="mermaid">stateDiagram-v2...</pre>` | ` ```mermaid stateDiagram... ``` ` | Mermaid source | State transitions |
+| **Timelines** |
+| Gantt chart | `<pre class="mermaid">gantt...</pre>` | ` ```mermaid gantt... ``` ` | Mermaid source | Project timeline |
+| Timeline | `<pre class="mermaid">timeline...</pre>` | ` ```mermaid timeline... ``` ` | Mermaid source | Event timeline |
+| **Data Viz** |
+| Pie chart | `<pre class="mermaid">pie title...</pre>` | ` ```mermaid pie... ``` ` | Mermaid source | Pie segments |
+| Bar chart | `<pre class="mermaid">bar...</pre>` | ` ```mermaid bar... ``` ` | Mermaid source | Bar graph |
+| Line chart | `<pre class="mermaid">line...</pre>` | ` ```mermaid line... ``` ` | Mermaid source | Line graph |
+| **Mind Map** |
+| Mind map | `<pre class="mermaid">mindmap...</pre>` | ` ```mermaid mindmap... ``` ` | Mermaid source | Hierarchical map |
+| **Git Graph** |
+| Git graph | `<pre class="mermaid">gitGraph...</pre>` | ` ```mermaid gitGraph... ``` ` | Mermaid source | Branch visualization |
+
+### Data Visualization (Vega & D3)
+
+| Type | HTML | CommonMark | Storage | Notes |
+|------|------|-----------|---------|-------|
+| **Vega Specs** |
+| Vega spec | `<div class="vega" data-spec="...">` | ` ```vega {...json...} ``` ` | JSON specification | Rendered via Vega-Lite |
+| Vega-Lite spec | Custom container | Code fence with JSON | JSON + metadata | High-level grammar |
+| **D3 Visualizations** |
+| D3 chart | `<svg class="d3">...SVG output...</svg>` | Not natively supported | SVG output (not source) | HTML-primary; MD shows placeholder |
+| Custom D3 | `<div id="chart">` + script | Not supported | HTML + JavaScript | Interactive charts |
+
+### Hand-Drawn & Geometric Content
+
+| Type | HTML | CommonMark | Storage | Editing |
+|------|------|-----------|---------|---------|
+| **Ink Drawings** |
+| Freehand stroke | `<svg class="ink"><path stroke="...">` | `[Hand-drawn image]` | SVG paths in assets | Ink editor UI |
+| Annotated ink | `<svg class="ink" data-id="...">` | Text description | SVG + metadata | Preserve layer info |
+| **Shapes** |
+| Rectangle | `<rect x="..." y="..." width="..." height="...">` | Not supported | SVG element | SVG visual |
+| Circle/Oval | `<circle cx="..." cy="..." r="...">` | Not supported | SVG element | SVG visual |
+| Line | `<line x1="..." y1="..." x2="..." y2="...">` | Not supported | SVG element | SVG visual |
+| Polygon | `<polygon points="...">` | Not supported | SVG path | SVG visual |
+| Free shape | `<path d="...">` | Not supported | SVG path data | SVG visual |
+| **Styling** |
+| Shape fill | `fill="color"` or `fill="url(#gradient)"` | Not supported | SVG fill attribute | Color or gradient |
+| Shape stroke | `stroke="color"` `stroke-width="..."` | Not supported | SVG stroke | Line color/width |
+| Opacity | `opacity="0.5"` or `fill-opacity="..."` | Not supported | SVG attribute | Transparency |
+| Shadow/Effect | `<filter><feDropShadow...>` | Not supported | SVG filter element | Visual effects |
+
+---
+
+## Media & Attachments
+
+### Images
+
+| Format | HTML | CommonMark | Storage | Status |
+|--------|------|-----------|---------|--------|
+| **Raster Images** |
+| PNG | `<img src="page_assets/file.png">` | `![alt](page_assets/file.png)` | `page_assets/` folder | ✓ Full support |
+| JPEG/JPG | `<img src="page_assets/file.jpg">` | `![alt](page_assets/file.jpg)` | `page_assets/` folder | ✓ Full support |
+| WebP | `<img src="page_assets/file.webp">` | `![alt](page_assets/file.webp)` | `page_assets/` folder | ✓ Full support |
+| GIF (static) | `<img src="page_assets/file.gif">` | `![alt](page_assets/file.gif)` | `page_assets/` folder | ✓ Full support |
+| GIF (animated) | `<img src="page_assets/anim.gif">` | `![alt](page_assets/anim.gif)` | `page_assets/` folder | ✓ Full support (plays) |
+| **Vector Images** |
+| SVG | `<img src="page_assets/file.svg">` | `![alt](page_assets/file.svg)` | `page_assets/` folder | ✓ Full support |
+| SVG (inline) | `<svg>...content...</svg>` | Not supported natively | Inline in HTML | ⚠ HTML-primary |
+| **Image Properties** |
+| Dimensions | `width="..." height="..."` | Not in Markdown | Implied from file | Preserved in HTML |
+| Alt text | `alt="description"` | `![description](...)`  | Both formats | ✓ Full parity |
+| Title/caption | `title="caption"` | `![...](... "caption")` | Both formats | ✓ Full parity |
+
+### Document Attachments
+
+| Type | HTML | CommonMark | Storage | Access |
+|------|------|-----------|---------|--------|
+| **Documents** |
+| PDF | `<a href="page_assets/file.pdf">` | `[PDF](page_assets/file.pdf)` | `page_assets/` folder | ✓ Downloadable link |
+| Word (.docx) | `<a href="page_assets/file.docx">` | `[Document](page_assets/file.docx)` | `page_assets/` folder | ✓ Downloadable link |
+| Excel (.xlsx) | `<a href="page_assets/file.xlsx">` | `[Spreadsheet](page_assets/file.xlsx)` | `page_assets/` folder | ✓ Downloadable link |
+| PowerPoint (.pptx) | `<a href="page_assets/file.pptx">` | `[Presentation](page_assets/file.pptx)` | `page_assets/` folder | ✓ Downloadable link |
+| Text file (.txt) | `<a href="page_assets/notes.txt">` | `[Text](page_assets/notes.txt)` | `page_assets/` folder | ✓ Downloadable link |
+| **Generic Files** |
+| Any file | `<a href="page_assets/file.ext">Download</a>` | `[File](page_assets/file.ext)` | `page_assets/` folder | ✓ Downloadable link |
+
+### Audio & Video
+
+| Type | HTML | CommonMark | Storage | Playback |
+|------|------|-----------|---------|----------|
+| **Video** |
+| MP4 | `<video src="page_assets/video.mp4">` | `[Video](page_assets/video.mp4)` | `page_assets/` | ✓ HTML5 player |
+| WebM | `<video src="page_assets/video.webm">` | `[Video](page_assets/video.webm)` | `page_assets/` | ✓ HTML5 player |
+| Fallback (multiple sources) | `<video><source src="..." type="..."></video>` | Multiple links | `page_assets/` | ✓ Browser picks best |
+| **Audio** |
+| MP3 | `<audio src="page_assets/sound.mp3">` | `[Audio](page_assets/sound.mp3)` | `page_assets/` | ✓ HTML5 player |
+| OGG | `<audio src="page_assets/sound.ogg">` | `[Audio](page_assets/sound.ogg)` | `page_assets/` | ✓ HTML5 player |
+| WAV | `<audio src="page_assets/sound.wav">` | `[Audio](page_assets/sound.wav)` | `page_assets/` | ✓ HTML5 player |
+
+---
+
+## Page Metadata & Structure
+
+| Element | HTML Storage | CommonMark Storage | Format | Status |
+|---------|--------------|-------------------|--------|--------|
+| **Document Metadata** |
+| Page title | `<title>` tag + `<h1>` | YAML front matter: `title:` | Plain text | ✓ Full parity |
+| Page ID | Meta `id` attribute | Front matter: `id:` | UUID/identifier | ✓ Full parity |
+| Created date | Meta `created` | Front matter: `created:` | ISO 8601 | ✓ Full parity |
+| Modified date | Meta `modified` | Front matter: `modified:` | ISO 8601 | ✓ Full parity |
+| Format type | Meta `format="html"` or `"cmgfm"` | Front matter: `format:` | Enum | ✓ Full parity |
+| Author/Owner | Meta `author` | Front matter: `author:` | Email/name | ✓ Full parity |
+| **Internationalization** |
+| Direction (LTR/RTL) | `dir="ltr"` or `dir="rtl"` on `<html>` | Front matter: `dir:` | Enum | ✓ Full parity |
+| Language | `lang="en-US"` | Front matter: `lang:` | BCP 47 tag | ✓ Full parity |
+| **Presentation** |
+| Custom CSS class | `class="custom-style"` on body | Front matter: `css_class:` | String | ✓ Full parity |
+| Theme (light/dark) | CSS variable override | Front matter: `theme:` | Enum | ✓ Full parity |
+
+---
+
+## Specialized Content Objects
+
+### Tags & Annotations
+
+| Marker | HTML Display | CommonMark | Visual Mark | Editable |
+|--------|--------------|-----------|------------|----------|
+| To Do | `☐` or checkbox | `- [ ]` in lists | Checkbox | ✓ Toggle |
+| Done | `☑` or checked | `- [x]` in lists | Checked box | ✓ Toggle |
+| Important | `⭐` prefix | `⭐ text` | Star icon | ✓ Toggle |
+| Question | `❓` prefix | `❓ text` | Question mark | ✓ Toggle |
+| Idea | `💡` prefix | `💡 text` | Light bulb | ✓ Toggle |
+| Remember | `📌` prefix | `📌 text` | Pushpin | ✓ Toggle |
+| Definition | `📖` prefix | `📖 text` | Book | ✓ Toggle |
+| Highlight | `🎨` prefix | `🎨 text` | Palette | ✓ Toggle |
+| Person/Contact | `👤` prefix | `👤 text` | Person icon | ✓ Toggle |
+| Location | `📍` prefix | `📍 text` | Pin icon | ✓ Toggle |
+| Phone | `📞` prefix | `📞 text` | Phone icon | ✓ Toggle |
+| Website | `🌐` prefix | `🌐 text` | Globe icon | ✓ Toggle |
+| Critical/Alert | `⚠️` prefix | `⚠️ text` | Warning | ✓ Toggle |
+
+### Containers & Layout Boxes
+
+| Type | HTML | CommonMark | Nesting | Status |
+|------|------|-----------|---------|--------|
+| **Single Column** |
+| Default content | No wrapper | Plain blocks | N/A | ✓ Standard |
+| **Multi-Column** |
+| Two-column box | `<div class="box" cols="2">` | Nested blockquotes (workaround) | Limited | ⚠ Layout support |
+| Three-column box | `<div class="box" cols="3">` | Not natively supported | Limited | ⚠ Limited support |
+| **Positioned** |
+| Positioned box | `<div class="box" style="position:absolute...">` | Not supported | N/A | ⚠ HTML-only |
+| Sidebar | `<aside>` or `<div class="sidebar">` | Not supported | N/A | ⚠ HTML-only |
+
+### Printouts & Export
+
+| Format | From HTML | From CommonMark | Engine | Output |
+|--------|-----------|-----------------|--------|--------|
+| **Print** |
+| PDF (print) | ✓ browser print-to-PDF | ✓ browser print-to-PDF | Browser | PDF file |
+| Page break | `<div class="page-break">` | `---` (mimics) | CSS/HTML | Hard page break |
+| Print styles | `@media print { }` | N/A | CSS | Print-only styling |
+| **Clipboard** |
+| Rich text (RTF) | ✓ via copy handler | ✓ via copy handler | HTML clipboard | RTF with formatting |
+| Plain text | ✓ stripped | ✓ stripped | Text | No formatting |
+| HTML source | ✓ as-is | N/A | HTML | Raw HTML code |
+| Markdown source | N/A | ✓ as-is | Markdown | Markdown code |
+| **Screenshot** |
+| PNG screenshot | ✓ Print as image | ✓ Rendered then image | Canvas API | Image file |
+
+---
+
+## Fidelity Rules (Non-Negotiable)
+
+### Rule 1: Content Parity
+Every piece of content in HTML format **must** exist identically in CommonMark format. No HTML-only content without explicit documentation of the gap.
+
+### Rule 2: Visual Parity
+At 1x zoom in light theme, both formats **must** render pixel-near identically:
+- Same font sizes, weights, and spacing
+- Same colors and contrast ratios
+- Same line heights and block spacing
+- Same image sizing and placement
+
+### Rule 3: Metadata Parity
+All page metadata (title, id, created, modified, direction, language) **must** be present in both:
+- HTML: in `<meta>` tags, `<title>`, and semantic HTML
+- CommonMark: in YAML front matter block
+
+### Rule 4: Asset Path Parity
+All asset references (images, files, attachments) **must** use:
+- Relative paths from the page directory
+- Identical structure: `page_assets/filename`
+- No absolute paths or format-specific references
+
+### Rule 5: Round-Trip Testing
+Every page **must** survive a full round trip without data loss:
+- HTML → parse → DOM → serialize → HTML (bitwise or semantically identical)
+- MD → parse → DOM → serialize → MD (semantically identical; whitespace may normalize)
+- Cross-format: HTML → MD → HTML (lossless bidirectional)
+
+### Rule 6: No Format-Only Features
+If a feature exists in one format, provide an equivalent in the other:
+- If CommonMark cannot natively support it, document the workaround
+- If truly impossible, mark as `⚠ Limited Support` and document in `docs/gaps.md`
+
+---
+
+## Questions Before Editing
+
+1. **What is the canonical semantic value?** - Not the rendering, the data meaning
+2. **Where is it serialized in HTML and CMGFM?** - Both representations of that meaning
+3. **Which metadata or companion file carries it?** - Attributes, front matter, separate assets?
+4. **Can another program read the page without NoteCraft and still see the data?** - Portability
+5. **What happens to unknown input or a format that cannot represent it?** - Graceful degradation
+6. **Which test proves read, write, reload, and cross-format behavior?** - Coverage
+
+---
+
+## Known Gaps & Workarounds
+
+| Gap | Root Cause | HTML Approach | CommonMark Approach | Status |
+|-----|-----------|---------------|--------------------|--------|
+| **Freehand Ink** | No native MD vector drawing | SVG paths in assets | Text placeholder | ⚠ Documented |
+| **Geometric Shapes** | MD has no shape primitives | SVG elements | ASCII art or text desc | ⚠ Limited |
+| **Multi-Column Layout** | MD has no box model | CSS `columns` or flexbox | Nested blockquotes | ⚠ Limited |
+| **Positioned Elements** | MD has no absolute positioning | CSS `position: absolute` | N/A | ⚠ HTML-only |
+| **Superscript/Subscript** | Not in GFM spec | `<sup>`, `<sub>` HTML tags | `^text^` or `~text~` (proposed) | ⚠ Non-standard |
+| **Custom Fonts** | Not in HTML/MD spec | `<link rel="stylesheet">` + CSS | `@import` font in front matter | ⚠ Limited |
+| **Advanced D3 Charts** | No native MD visualization | `<svg>` output or `<div>` holder | Code fence with spec | ⚠ Experimental |
+| **Video Streaming** | HLS/DASH not std in HTML | `<video>` with HLS source | Link to video URL | ⚠ Limited |
+
+---
 
-1. What is the canonical semantic value?
-2. Where is it serialized in HTML and CMGFM?
-3. Which metadata or companion file carries it?
-4. Can another program read the page without NoteCraft and still see the data?
-5. What happens to unknown input or a format that cannot represent it?
-6. Which test proves read, write, reload, and cross-format behavior?
+**Last Updated:** 2026-10-27  
+**Format Status:** Complete and authoritative  
+**Sync Requirement:** All content types must achieve parity before release