---
name: diagram-design
description: Create branded architecture, architecture delta, IT current-state, flowchart, sequence, state machine, ER/data model, timeline, swimlane, quadrant, radar/spider, polar chart (polar/radial lollipop), loop/flywheel, nested, tree, org chart, layer stack, Venn, pyramid/funnel, treemap and marimekko, heatmap, bar and dumbbell, waterfall, line (slopegraph, ridgeline, streamgraph, bump), Gantt and scatter charts (bubble, beeswarm), high-level, process, medallion, data flow, DP integration, DP security matrix, Sankey, fishbone, Wardley map, kanban, user journey, deployment, dependency graph, UML class, story map, or database schema diagrams as HTML/SVG/PNG, with .drawio, Mermaid, and .excalidraw import, plus lifecycle phase maps, block decomposition trees, and onboarding guidance.
license: MIT
metadata:
version: "2.6"
---
# Diagram Design
Create diagrams as self-contained HTML files with inline SVG and an editorial design system.
Forty-two visual types. Semantic patterns describe behavior; type references describe layout.
---
## 0. First-time setup — style guide gate
**Before generating your first diagram in a new project, verify the style guide has been customized.**
Do not silently ship default-skinned diagrams into a branded project.
First resolve any project `.diagram-design` marker per [`references/profiles.md`](references/profiles.md); a successfully resolved marker selects its profile and bypasses this gate. That reference owns failures, the protected default, and save behavior.
Open [`references/style-guide.md`](references/style-guide.md) and check the default tokens. If they are still the shipped defaults (paper `#f5f5f5`, ink `#2d3142`, accent `#eb6c36`), **pause and ask the user**:
> *"This is your first diagram in this project and the style guide is still default. Customize now? Options: (a) website URL, (b) installed skill, (c) local folder/design-system, (d) paste tokens, (e) keep default, (f) load saved profile."*
Then branch per the matching section of [`references/onboarding.md`](references/onboarding.md); for **(f)** follow [`references/profiles.md`](references/profiles.md).
**Once the style guide has been customized** (or the user explicitly chose default), skip this gate on later runs. A leading profile header names the copied-in active profile. Without a header, any semantic-role value or typography family differing from shipped defaults means **custom-unsaved**: skip the gate and offer to save it as a profile. All-default tokens with no marker/header trigger the gate. After onboarding, offer to save as a named client profile per `references/profiles.md`.
---
## 1. Philosophy
**The highest-quality move is usually deletion.**
Applied to schematics:
- Every node represents a distinct idea. Two nodes that always travel together are one node.
- Every connection carries information. If the relationship is obvious from layout, remove the line.
- Coral is **editorial, not a flag.** 1–2 focal nodes per diagram. Using it on 5 nodes erases the signal.
- The schematic isn't done when everything is added. It's done when nothing can be removed.
**Target density: 4/10.** Enough to be technically complete. Not so dense it needs a guide. Above 9 nodes, it's probably two diagrams.
---
## 2. When to Use
Use for any of the 42 visual types (§3) when a reader will learn more from a visual than from prose, a table, or a bulleted list.
**Don't use for:**
- Quick unicode diagrams → use **wiretext**.
- Lists of things → table or bullets.
- Attribute-only before/after → table; topology changes → Architecture delta.
- One-shape "diagrams" → just write the sentence.
Before drawing, ask: *Would the reader learn more from this than from a well-written paragraph?* If no, don't draw.
---
## 3. Selection: semantic pattern, then visual type
When behavior, state, enforcement, or risk carries the meaning, first load [`references/semantic-patterns.md`](references/semantic-patterns.md) and choose one primary pattern. Then choose the nearest visual type for layout. If no pattern matches, choose the type directly.
| Behavioral trigger | Semantic pattern → nearest type |
|---|---|
| Fan-in, queue depth, finite capacity, bottleneck | **Fan-in queue / bottleneck** → Data flow |
| Repeated Question / Input / Governance / Output slots across stages | **Stage framework with semantic slots** → Process |
| Conversation or loose input becomes a structured durable artifact | **Unstructured input → structured artifact** → Data flow |
| Two rule traces need pass/fail/skipped/not-reached and first divergence | **Paired policy-evaluation traces** → Flowchart |
| Trust boundaries plus permitted/forbidden ingress or deploy paths | **Secure paved road** → Architecture |
| Controls grouped by where they are enforced | **Governance / control catalog** → Layer stack |
| Defenses compensate for prior gaps and residual risk propagates | **Compensating security layers** → Layer stack |
| Hierarchical, ID-addressable decomposition needing per-block I/O, constraints, and a code link | **Traceable block decomposition** → Tree |
| One subject progresses through phases, waits, retries, cancellation, and terminal outcomes | **Lifecycle phase map** → State Machine |
The pattern owns semantic primitives and its tighter budget; the type owns layout grammar. Use [`references/animation.md`](references/animation.md) only when motion is requested or materially clarifies ordered change; static remains the default.
### Visual-type guide (42)
| If you're showing… | Use | Reference |
|---|---|---|
| Components + connections in one system snapshot | **Architecture** | [type-architecture.md](references/type-architecture.md) |
| Structural change between synchronized Before / After topologies, with a Changes ledger | **Architecture delta** | [type-architecture-delta.md](references/type-architecture-delta.md) |
| Legacy IT landscape by phase or department; shows the *before* state | **IT current-state** | [type-it-state.md](references/type-it-state.md) |
| Decision logic with branches | **Flowchart** | [type-flowchart.md](references/type-flowchart.md) |
| Time-ordered messages between actors | **Sequence** | [type-sequence.md](references/type-sequence.md) |
| States + transitions + guards | **State machine** | [type-state.md](references/type-state.md) |
| Entities + fields + relationships | **ER / data model** | [type-er.md](references/type-er.md) |
| Events positioned in time | **Timeline** | [type-timeline.md](references/type-timeline.md) |
| Cross-functional process with handoffs | **Swimlane** | [type-swimlane.md](references/type-swimlane.md) |
| Two-axis positioning / prioritization | **Quadrant** | [type-quadrant.md](references/type-quadrant.md) |
| Multiple entities scored across 3–5 quantitative criteria | **Radar / Spider** | [type-radar.md](references/type-radar.md) |
| One quantitative series across cyclic categories; angle=category, radius=magnitude | **Polar chart** | [type-polar.md](references/type-polar.md) |
| Reinforcing cycle; the last step feeds the first and a hub accumulates state | **Loop** | [type-loop.md](references/type-loop.md) |
| Hierarchy through containment / scope | **Nested** | [type-nested.md](references/type-nested.md) |
| Parent → children relationships | **Tree** | [type-tree.md](references/type-tree.md) |
| Human/agent/team ownership, reporting, routing, escalation | **Org chart** | [type-org-chart.md](references/type-org-chart.md) |
| Stacked abstraction levels | **Layer stack** | [type-layers.md](references/type-layers.md) |
| Overlap between sets | **Venn** | [type-venn.md](references/type-venn.md) |
| Ranked hierarchy or conversion drop-off | **Pyramid / funnel** | [type-pyramid.md](references/type-pyramid.md) |
| Quantitative comparison across categories | **Bar chart** | [type-bar.md](references/type-bar.md) |
| A start total bridged to an end total by signed contributions (budget bridge, headcount deltas) | **Waterfall** | [type-waterfall.md](references/type-waterfall.md) |
| Part-of-whole where the relative sizes are the story | **Treemap** | [type-treemap.md](references/type-treemap.md) |
| Cross-tabulated data; fill encodes value per cell | **Heatmap** | [type-heatmap.md](references/type-heatmap.md) |
| Continuous trends over time, change between exactly two states (slopegraph), one distribution per series (ridgeline), or rank movement across several snapshots (bump) | **Line chart** | [type-line.md](references/type-line.md) |
| Tasks and phases on a timeline | **Gantt** | [type-gantt.md](references/type-gantt.md) |
| Correlation or distribution of two variables; bubble (three variables) and beeswarm (one variable, dot per item) variants | **Scatter plot** | [type-scatter.md](references/type-scatter.md) |
| End-to-end data stack on a container cluster | **High-Level** | [type-high-level.md](references/type-high-level.md) |
| Multi-actor sequential process with data handoffs | **Process** | [type-process.md](references/type-process.md) |
| Multi-tier data storage with quality levels and access policies | **Medallion** | [type-medallion.md](references/type-medallion.md) |
| Role-scoped data flow: who does what at each pipeline step | **Data flow** | [type-data-flow.md](references/type-data-flow.md) |
| Integration topology of a data platform — sources → core → consumers | **DP integration** | [type-dp-integration.md](references/type-dp-integration.md) |
| Per-role / per-component access permissions matrix | **DP security matrix** | [type-dp-security-matrix.md](references/type-dp-security-matrix.md) |
| A quantity splitting and merging across stages, band width = amount | **Sankey** | [type-sankey.md](references/type-sankey.md) |
| Causes of one observed effect, grouped by category (root-cause analysis) | **Fishbone** | [type-fishbone.md](references/type-fishbone.md) |
| Value chain against evolution — what to build, buy, and what is moving | **Wardley map** | [type-wardley.md](references/type-wardley.md) |
| Work-in-progress by state, with WIP limits and blocked items | **Kanban** | [type-kanban.md](references/type-kanban.md) |
| What a person does across stages of an experience, and how it feels | **User journey** | [type-journey.md](references/type-journey.md) |
| Where software runs — zones, hosts, artifacts, replicas, ports | **Deployment** | [type-deployment.md](references/type-deployment.md) |
| What depends on what, with fan-in and cycles a tree cannot express | **Dependency graph** | [type-dependency.md](references/type-dependency.md) |
| Classes with operations, inheritance, composition (other UML routes elsewhere) | **UML class** | [type-uml-class.md](references/type-uml-class.md) |
| Narrative backbone sliced into releases, with the cut line | **Story map** | [type-story-map.md](references/type-story-map.md) |
| Physical tables: SQL types, constraints, indexes, column-level FKs | **Database schema** | [type-db-schema.md](references/type-db-schema.md) |
Rules of thumb:
- If a 3-column table communicates the same thing, pick the table.
- If two types seem useful, pick the dominant axis; a semantic pattern may add behavior-specific primitives, not a second layout grammar.
- If you're past the complexity budget (§7), split into an overview + detail.
**Always load the chosen type reference linked in the guide before drawing.** When routed above, also load `semantic-patterns.md`; when animation is chosen, load `animation.md`.
### Confirm before drawing
Before rendering, state the plan in one short message: the chosen visual type (and semantic pattern, if routed), the size preset, and anything the complexity budget (§7) will force out. If the user is reachable, let them redirect before you draw; if not, proceed and note the assumptions beside the deliverable. Skip the pause only when the request already pins type, size, and content exactly.
---
## 4. Universal Anti-patterns
These mark "AI slop" schematics of any type:
| Anti-pattern | Why it fails |
|---|---|
| Dark mode + cyan/purple glow | Looks "technical" without design decisions |
| JetBrains Mono as blanket "dev" font | Mono is for *technical* content — ports, commands, URLs. Names go in Geist sans. |
| Identical boxes for every node | Erases hierarchy |
| Legend floating inside the diagram area | Collides with nodes |
| Arrow labels with no masking rect | Bleeds through the line |
| Vertical `writing-mode` text on arrows | Unreadable |
| 3 equal-width summary cards as default | Generic grid — vary widths |
| Shadow on any element | Shadows are out. Borders are in. |
| `rounded-2xl` on boxes | Max radius 6–10px or none |
| Coral on every "important" node | Coral is 1–2 editorial accents, not a signaling system |
| Reproducing Mermaid's renderer layout | Imports automatic spacing and routing instead of making an editorial layout |
| Any breach of the six §6 connector rules | Automatic fail: diagonal slants, labels touching their stroke, masks clipped by a later node, overlapping paths, shared attach points, transit behind a non-endpoint box |
Type-specific anti-patterns live in each type reference linked in the guide.
---
## 5. Design System
**The design system is skinnable.** [`references/style-guide.md`](references/style-guide.md) is the single source of truth for colors, typography, tokens, and the default palette; this file names semantic roles (`paper`, `ink`, `muted`, `accent`, `link`, …). To apply a brand, edit `style-guide.md` or run the URL-based flow in [`references/onboarding.md`](references/onboarding.md).
> When specs below or in type references mention "ink", "accent", "muted", etc., look up the current hex value in `style-guide.md`.
### Semantic roles (at a glance)
| Role | Purpose |
|---|---|
| `paper`, `paper-2` | Page bg and container bg |
| `ink` | Primary text / stroke |
| `muted`, `soft` | Secondary text, default arrows, sublabels |
| `rule`, `rule-solid` | Hairline borders |
| `accent`, `accent-tint` | 1–2 focal elements per diagram |
| `link` | HTTP/API calls, external arrows |
**Focal rule:** `accent` goes on 1–2 elements max. Everything else is `ink` / `muted` / `soft`. If you're tempted to accent 4 things, you haven't decided what's focal yet.
**Node treatments** (focal, backend/API/step, store/state, external/cloud, input/user, optional/async, security/boundary): fill and stroke per [style-guide.md § Node type → treatment](references/style-guide.md#node-type--treatment).
**Typography:** Instrument Serif for the H1 title and italic callouts, Geist sans 600 for node names, Geist Mono for sublabels, eyebrows, and arrow labels. Sizes, weights, and the font ``: [style-guide.md § Typography](references/style-guide.md#typography); per-preset type ramp: [output-spec.md](references/output-spec.md).
**Non-Latin labels** — extend the family: [Korean](references/style-guide.md#korean-labels), [Chinese](references/style-guide.md#traditional-chinese-labels), [Cyrillic](references/style-guide.md#cyrillic-labels).
**Mono is for technical content only** — never as a blanket "dev" font, and never JetBrains Mono.
---
## 6. Core SVG Primitives
Universal building blocks. Type-specialized primitives (lifeline, activation bar, region) live in the relevant type reference linked in the guide. Optional primitives:
- Editorial callouts → [primitive-annotation.md](references/primitive-annotation.md)
- Hand-drawn variant → [primitive-sketchy.md](references/primitive-sketchy.md)
- Icon set (laptop, server, DB, K8s, Docker, AWS, …) → [primitive-icons.md](references/primitive-icons.md). Browse the gallery at [`assets/icons.html`](assets/icons.html).
- Terminal / CLI-window variant → [primitive-terminal.md](references/primitive-terminal.md)
- Optional explanatory motion → [animation.md](references/animation.md)
Exact markup (background, dotted paper, markers, node box, arrow label, legend) and the long form of each connector rule: [`references/primitives-core.md`](references/primitives-core.md). The static templates (`template.html`, `template-dark.html`, `template-full.html`) already define the background and the `arrow`, `arrow-accent`, and `arrow-link` markers; `template-motion.html` defines only its own prefixed marker, so add the others from primitives-core.md when a motion diagram needs them.
- **Arrows:** `muted` by default, `accent` for the headline path, `link` for HTTP/API and external calls, dashed `5,4` for optional, passive, return, or async. Draw arrows before boxes so lines sit behind nodes.
- **Node box:** an opaque paper mask rect, then the styled box at `rx=6`, a rectangular type tag at `rx=2` (not a pill), the name in Geist 600, and a Geist Mono sublabel.
### Mandatory connector rules
Non-negotiable, and §9 checks each one. Full text and edge cases: [primitives-core.md § Mandatory connector rules](references/primitives-core.md#mandatory-connector-rules).
1. **Orthogonal only.** Connectors between off-axis nodes are rounded right-angle elbows at `r=8` (`r=6` minimum in tight layouts); a straight `` only when both ends share x or y. Diagonals fail.
2. **Label gap.** Every arrow label (14 characters max, all caps, centered on its segment) sits on an opaque mask with a visible 6 to 10px gap from its stroke, beside vertical segments, never on the line.
3. **No overlaps.** No shared or stacked strokes: offset parallel routes by 12px or more, and use the bridge/hop at a single crossing.
4. **Fan attach points.** Connectors on one box edge each get their own point at `L * k / (N + 1)`, 12px or more apart (8px on very small boxes).
5. **No transit behind a non-endpoint box.** Reroute. Only when the box is geometrically unavoidable: dashed stroke (`4,3`), label at the visible end, no marker on the intervening box.
6. **Mask before node.** A label mask must not overlap a node drawn after it; badge masks fully inside a node and masks over earlier zones are fine. From a repository checkout, verify with `python3 /scripts/verify-geometry.py `.
---
## 7. Layout & Spacing
Structural geometry sits on a 4px grid: node origins, widths, heights, gaps, and padding divide by 4. Type sizes follow the role ramp in [output-spec.md](references/output-spec.md), not the grid. Allowed values, the off-grid exceptions, and page layout: [`references/layout-budget.md`](references/layout-budget.md).
### Complexity budget (per diagram)
| Limit | Rule |
|---|---|
| Max nodes | 9 |
| Max arrows / transitions | 12 |
| Max coral elements | 2 |
| Max annotation callouts | 2 |
| Max motion (optional) | 8 steps, 12 marked items, 2 simultaneous items — see [animation.md](references/animation.md) |
Per-type limits (lifelines, lanes, series, bars, stages, and the rest): [layout-budget.md § Complexity budget](references/layout-budget.md#complexity-budget-per-diagram). Check your type's row before drawing.
If you exceed, split into two diagrams (overview + detail).
---
## 8. Summary Card Pattern
Don't use 3 identical generic cards. Vary the treatment: column widths such as `1.1fr 1fr 0.9fr`, a white background with a 1px hairline border and 6px radius, no `box-shadow`. Markup and the card-dot variants: [layout-budget.md § Summary Card Pattern](references/layout-budget.md#summary-card-pattern).
---
## 9. Pre-Output Checklist (Taste Gate)
Run before producing any diagram.
**Type fit:**
- [ ] If behavior matters, did I choose one semantic pattern before the visual type and load `semantic-patterns.md`?
- [ ] Right visual type for the layout? (§3 visual-type guide)
- [ ] Stated type, pattern, size preset, and planned cuts before drawing — confirmed, or assumptions noted? (§3)
- [ ] Would a table / paragraph do the same job? (If yes — don't draw.)
- [ ] Loaded the matching type reference linked in the visual-type guide?
- [ ] If this is an import — format, size, detail level, and audience set? `viewBox` and type ramp match the size preset? (§11, [output-spec.md §6](references/output-spec.md))
- [ ] If this is an import — fidelity ledger ready to report? (§11)
**Remove test:**
- [ ] Can I remove any node? (Would a reader still understand?)
- [ ] Can I merge any two nodes? (Do they always travel together?)
- [ ] Can I remove any arrow? (Is the relationship obvious from layout?)
- [ ] Can I remove any label? (Does color or shape already signal it?)
**Signal:**
- [ ] Coral used on ≤2 elements? If more, which actually deserve focal status?
- [ ] Legend covers every type used — and nothing extra?
- [ ] Within the type's complexity budget (§7)?
**Technical:**
- [ ] Diagram `