Breadboarding

2. Designing from Shaped Parts

You have a new system sketched as an assembly of parts (mechanisms) per shaping. You need to detail out the concrete mechanism and show how those parts interact as a system.

Input:

• Parts list (mechanisms from shaping)
• The R (requirement/outcome) the parts are meant to achieve
• Existing system (optional) — if the new parts must interoperate with existing code

Output:

• UI Affordances table
• Code Affordances table
• (Optional) Mermaid visualization

Mixtures

Often you have both: an existing system that must remain as-is, plus new pieces or changes defined in a shape. In this case, breadboard both together — the existing affordances and the new ones — showing how they connect.

3. Reading a Whiteboard Breadboard

Hand-drawn or whiteboard breadboards use a visual stacking format rather than tables. The same concepts apply (Places, affordances, wiring) but the layout conventions differ.

Visual conventions:

How to read a whiteboard breadboard:

1. Identify places — Find the colored header blocks at the top of each stack
2. Read each stack top-to-bottom — Everything stacked under a place belongs to that place
3. Find loaders — Code affordances at the top-left of a place block describe what data is needed to render
4. Trace wiring — Follow arrows between stacks for control flow (solid) and data flow (dashed)
5. Note conditionals — Indented blocks with different colors show branching logic within a place
6. Check containing boxes — Large boundaries indicate system/responsibility boundaries
7. Flag speculative items — ? and ~ prefixed items are uncertain and may not survive shaping

Translating to tables: When converting a whiteboard breadboard to standard affordance tables, map each stack to its Place, enumerate the affordances top-to-bottom, and capture the arrows as Wires Out / Returns To relationships. Loaders become code affordances with Returns To pointing at the UI affordances they feed.

Core Concepts

Places

A Place is a bounded context of interaction. While you're in a Place:

• You have a specific set of affordances available to you
• You cannot interact with affordances outside that boundary
• You must take an action to leave

Place is perceptual, not technical. It's not about URLs or components — it's about what the user experiences as their current context. A Place is "where you are" in terms of what you can do right now.

The Blocking Test

The simplest test for whether something is a different Place: Can you interact with what's behind?

Examples

Local State vs Place Navigation

When a control changes state, ask: did everything change, or just a subset while the surroundings stayed the same?

Mode-Based Places

When a mode (like "edit mode") transforms the entire screen — different buttons, different affordances everywhere — model as separate Places:

PLACE: CMS Page (Read Mode)
PLACE: CMS Page (Edit Mode)

The state flag (e.g., editMode$) that switches between them is a navigation mechanism, not a data store. Don't include it as an S in either Place.

Three Questions for Any Control

For any UI affordance, ask:

1. Where did I come from to see this?
2. Where am I now?
3. Where do I go if I act on it?

If the answer to #3 is "everything changes" or "I can't interact with what's behind until I respond," that's navigation to a different Place.

Labeling Conventions

When spanning multiple systems, label with the system: PLACE: Checkout Page (frontend), PLACE: Payment API (backend).

Place IDs

Places are first-class elements in the data model. Each Place gets an ID:

Place IDs enable:

• Explicit navigation wiring — wire → P2 instead of to an affordance inside
• Containment tracking — each affordance declares which Place it belongs to
• Consistent Mermaid subgraphs — subgraph ID matches Place ID

Place References

When a nested place has lots of internal affordances and would clutter the parent, you can detach it:

1. Put a reference node in the parent place using underscore prefix: _letter-browser
2. Define the full place separately with all its internals
3. Wire from the reference to the place: _letter-browser --> letter-browser

The reference is a UI affordance — it represents "this widget/component renders here" in the parent context.

flowchart TB
subgraph P1["P1: CMS Page (Read Mode)"]
    U1["U1: Edit button"]
    U_LB["_letter-browser"]
end

subgraph letterBrowser["letter-browser"]
    U10["U10: Search input"]
    U11["U11: Letter list"]
    N40["N40: performSearch()"]
end

U_LB --> letterBrowser

In affordance tables, list the reference as a UI affordance:

Style place references with a dashed border to distinguish them:

classDef placeRef fill:#ffb6c1,stroke:#d87093,stroke-width:2px,stroke-dasharray:5 5
class U_LB placeRef

Modes as Places

When a component has distinct modes (read vs edit, viewing vs editing, collapsed vs expanded), model them as separate places — they're different perceptual states for the user.

If one mode includes everything from another plus more, show this with a place reference inside the extended place:

P3: letter-browser (Read)    — base state
P4: letter-browser (Edit)    — contains _letter-browser (Read) + new affordances

The reference shows composition: "everything in P3 appears here, plus these additions."

flowchart TB
subgraph P3["P3: letter-browser (Read)"]
    U10["U10: Search input"]
    U11["U11: Letter list"]
end

subgraph P4["P4: letter-browser (Edit)"]
    U_P3["_letter-browser (Read)"]
    U3["U3: Add button"]
    U4["U4: Edit button"]
end

U_P3 --> P3

In affordance tables for P4, the reference shows inheritance:

Subplaces

A subplace is a defined subset of a Place — a contained area that groups related affordances. Use subplaces when:

• A Place contains multiple distinct widgets or sections
• You're detailing one part of a larger Place
• You want to show what's in scope vs out of scope

Notation: Use hierarchical IDs — P2.1, P2.2, etc. for subplaces of P2.

| # | Place | Description |
|---|-------|-------------|
| P2 | Dashboard | Main dashboard page |
| P2.1 | Sales widget | Subplace: sales metrics |
| P2.2 | Activity feed | Subplace: recent activity |

In affordance tables, use the subplace ID to show containment:

| U3 | P2.1 | sales-widget | "Refresh" button | click | → N4 | — |
| U7 | P2.2 | activity-feed | activity list | render | — | — |

In Mermaid: Nest the subplace subgraph inside the parent. Use the same background color (no distinct fill) — the subplace is part of the parent, not a separate Place:

flowchart TB
subgraph P2["P2: Dashboard"]
    subgraph P2_1["P2.1: Sales widget"]
        U3["U3: Refresh button"]
    end
    subgraph P2_2["P2.2: Activity feed"]
        U7["U7: activity list"]
    end
    otherContent[["... other dashboard content ..."]]
end

Placeholder for out-of-scope content: When detailing one subplace, add a placeholder sibling to show there's more on the page:

otherContent[["... other page content ..."]]

This tells readers: "we're zooming in on P2.1, but P2 contains more that we're not detailing."

Containment vs Wiring

These are two different relationships in the data model:

Containment is set membership: U1 ∈ P1 means U1 is a member of Place P1. Every affordance belongs to exactly one Place.

Wiring is control flow: U1 → N1 means U1 triggers N1. An affordance can wire to anything — other affordances or Places.

The Place column answers: "Where does this affordance live?" The Wires Out column answers: "What does this affordance trigger?"

Navigation Wiring

When an affordance causes navigation (user "goes" somewhere), wire to the Place itself, not to an affordance inside:

✅ N1 Wires Out: → P2          (navigate to Edit Mode)
❌ N1 Wires Out: → U3          (wiring to affordance inside P2)

This makes navigation explicit in the tables. The Place is the destination; specific affordances inside become available once you arrive.

In Mermaid, this becomes:

N1 --> P2

The subgraph ID matches the Place ID, so the wire connects to the Place boundary.

Affordances

Things you can act upon:

• UI affordances (U): inputs, buttons, displayed elements, scroll regions
• Code affordances (N): methods, subscriptions, data stores, framework mechanisms

Wiring

How affordances connect to each other:

Wires Out — What an affordance triggers or calls (control flow):

• Call wires: one affordance calls another
• Write wires: code writes to a data store
• Navigation wires: routing to a different place

Returns To — Where an affordance's output flows (data flow):

• Return wires: function returns value to its caller
• Read wires: data store is read by another affordance

This separation makes data flow explicit. Wires Out show control flow (what triggers what). Returns To show data flow (where output goes).

The Output: Affordance Tables

The tables are the truth. Every breadboard produces these:

Places Table

UI Affordances Table

Code Affordances Table

Data Stores Table

Column Definitions

Procedures

For Mapping an Existing System

See Example A below for a complete worked example.

Step 1: Identify the flow to analyze

Pick a specific user journey. Always frame it as an operator trying to do something:

• "Land on /search, type query, scroll for more, click result"
• "Call the payment API with a card token, expect a charge to be created"

Step 2: List all places involved

Walk through the journey and identify each distinct place the user visits or system boundary crossed.

Step 3: Trace through the code to find components

Starting from the entry point (route, API endpoint), trace through the code to find every component touched by that flow.

Step 4: For each component, list its affordances

Read the code. Identify:

• UI: What can the user see and interact with?
• Code: What methods, subscriptions, stores are involved?

Step 5: Name the actual thing, not an abstraction

If you write "DATABASE", stop. What's the actual method? (userRepo.save()). Every affordance name must be something real you can point to in the code.

Step 6: Fill in Control column

For each affordance, what triggers it? (click, type, call, observe, write, render)

Step 7: Fill in Wires Out

For each affordance, what does it trigger? Read the code — what does this method call? What does this button's handler invoke?

Step 8: Fill in Returns To

For each affordance, where does its output flow?

• Functions that return values → list the callers that receive the return
• Data stores → list the affordances that read from them
• No meaningful output → use —

Step 9: Add data stores as affordances

When code writes to a property that is later read by another affordance, add that property as a Code affordance with control type write.

Step 10: Add framework mechanisms as affordances

Include things like cdr.detectChanges() that bridge between code and UI rendering. These show how state changes actually reach the UI.

Step 11: Verify against the code

Read the code again. Confirm every affordance exists and the wiring matches reality.

For Designing from Shaped Parts

See Example B below for a complete worked example including slicing.

Step 1: List each part from the shape

Take each mechanism/part identified in shaping and write it down.

Step 2: Translate parts into affordances

For each part, identify:

• What UI affordances does this part require?
• What Code affordances implement this part?

Step 3: Verify every U has a supporting N

For each UI affordance, check: what Code affordance provides its data or controls its rendering? If none exists, add the missing N.

Step 4: Classify places as existing or new

For each UI affordance, determine whether it lives in:

• An existing place being modified
• A new place being created

Step 5: Wire the affordances

Fill in Wires Out and Returns To for each affordance. Trace through the intended behavior — what calls what? What returns where?

Step 6: Connect to existing system (if applicable)

If there's an existing codebase:

• Identify the existing affordances the new ones must connect to
• Add those existing affordances to your tables
• Wire the new affordances to them

Step 7: Check for completeness

• Every U should have an N that feeds it
• Every N should have either Wires Out or Returns To (or both)
• Handlers → should have Wires Out
• Queries → should have Returns To
• Data stores → should have Returns To

Step 8: Treat user-visible outputs as Us

Anything the user sees (including emails, notifications) is a UI affordance and needs an N wiring to it.

Key Principles

Never use memory — always check the data

When tracing a flow backwards, don't follow the path you remember. Scan the Wires Out column for ALL affordances that wire to your target.

When filling in the tables, read each row systematically. Don't rely on what you think you know.

The tables are the source of truth. Your memory is unreliable.

Every affordance name must exist (when mapping)

When mapping existing code, never invent abstractions. Every name must point to something real in the codebase.

Mechanisms aren't affordances

An affordance is something you can act upon that has meaningful identity in the system. Several things look like affordances but are actually just implementation mechanisms:

These aren't always obvious on first draft. When reviewing your affordance tables, double-check each Code affordance and ask:

"Is this actually an affordance, or is it just detailing the mechanism for how something happens?"

If it's just the "how" — skip it and wire directly to the destination or outcome.

Examples:

❌ N8 --> N22 --> P3     (N22 is modalService.open — just mechanism)
✅ N8 --> P3             (handler navigates to modal)

❌ N6 --> N20 --> S2     (N20 is data transform — internal to N6)
✅ N6 --> S2             (callback writes to store)

❌ U7: modal-frame       (wrapper — just the boundary of P3)
✅ U8: Save button       (actionable)

The handler navigates to P3. The callback writes to the store. The modal IS P3. The mechanisms are implicit.

Two flows: Navigation and Data

A breadboard captures two distinct flows:

These are orthogonal. You can have navigation without data changes, and data changes without navigation.

When reviewing a breadboard, trace both flows:

1. Navigation flow: Can you follow the user's journey from Place to Place?
2. Data flow: For every U that displays data, can you trace where that data comes from?

Every U that displays data needs a source

A UI affordance that displays data must have something feeding it — either a data store (S) or a code affordance (N) that returns data.

❌ U6: letter list (no incoming wire — where does the data come from?)
✅ S1 -.-> U6 (store feeds the display)
✅ N4 -.-> U6 (query result feeds the display)

If a display U has no data source wiring into it, either:

1. The source is missing from the breadboard
2. The U isn't real

This is easy to miss when focused on navigation. Always ask: "This U shows data — where does that data come from?"

Every N must connect

If a Code affordance has no Wires Out AND no Returns To, something is wrong:

• Handlers → should have Wires Out (what they call or write)
• Queries → should have Returns To (who receives their return value)
• Data stores → should have Returns To (which affordances read them)

Side effects need stores

An N that appears to wire nowhere is suspicious. If it has side effects outside the system boundary (browser URL, localStorage, external API, analytics), add a store node to represent that external state:

❌ N41: updateUrl()           (wires to... nothing?)
✅ N41: updateUrl() → S15     (wires to Browser URL store)

This makes the data flow explicit. The store can also have return wires showing how external state flows back in:

flowchart TB
N42["N42: performSearch()"] --> N41["N41: updateUrl()"]
N41 --> S15["S15: Browser URL (?q=)"]
S15 -.->|back button / init| N40["N40: activeQuery$"]

Common external stores to model:

• Browser URL — query params, hash fragments
• localStorage / sessionStorage — persisted client state
• Clipboard — copy/paste operations
• Browser History — navigation state

Separate control flow from data flow

Wires Out = control flow (what triggers what) Returns To = data flow (where output goes)

This separation makes the system's behavior explicit.

Show navigation inline, not as loops

Routing is a generic mechanism every page uses. Instead of drawing all navigation through a central Router affordance, show Router navigate() inline where it happens and wire directly to the destination place.

Place stores where they enable behavior, not where they're written

A data store belongs in the Place where its data is consumed to enable some effect — not where it's produced. Writes from other Places are "reaching into" that Place's state.

To determine where a store belongs:

1. Trace read/write relationships — Who writes? Who reads?
2. The readers determine placement — that's where behavior is enabled
3. If only one Place reads, the store goes inside that Place

Example: A changedPosts array is written by a Modal (when user confirms changes) but read by a PAGE_SAVE handler (when user clicks Save). The store belongs with the PAGE_SAVE handler — that's where it enables the persistence operation.

Only extract to shared areas when truly shared

Before putting a store in a separate DATA STORES section, verify it's actually read by multiple Places. If it only enables behavior in one Place, it belongs inside that Place.

Nest stores in the subcomponent that reads them

Within a Place, put stores in the subcomponent where they enable behavior. If a store is read by a specific handler, put it in that handler's component — not floating at the Place level.

Backend is a Place

The database and resolvers aren't floating infrastructure — they're a Place with their own affordances. Database tables (S) belong inside the Backend Place alongside the resolvers (N) that read and write them.

Catalog of Parts and Relationships

This section provides a complete reference of everything that can appear in a breadboard.

Elements

Relationships

Containment vs Wiring

Containment is set membership: U1 ∈ P1 means U1 is a member of Place P1. Wiring is control flow: U1 → N1 means U1 triggers N1.

What Qualifies as Each Element

Place (P):

• Passes the blocking test — can't interact with what's behind
• Examples: modal, edit mode (whole screen transforms), route/page
• Not: dropdown, tooltip, checkbox revealing fields

Place Reference (_PlaceName):

• A UI affordance that represents a detached place
• Use when a nested place has many affordances and would clutter the parent
• Examples: _letter-browser, _user-profile-widget
• Wires to the full place definition: _letter-browser --> P3

UI Affordance (U):

• User can see it or interact with it
• Examples: button, input, list, spinner, displayed text
• Not: wrapper elements, layout containers

Code Affordance (N):

• Has meaningful identity — you can point to it in code
• Examples: handleSubmit(), query$ subscription, detectChanges()
• Not: internal transforms, navigation mechanisms (see below)

Data Store (S):

• State that is written and read
• Examples: results array, loading boolean, changedPosts list
• External stores: Browser URL, localStorage, Clipboard — represent state outside the app boundary
• Not: config that's set once and never changes (consider as config affordance)

Verification Checks

Chunking

Chunking collapses a subsystem into a single node in the main diagram, with details shown separately. Use chunking to manage complexity when a section of the breadboard has:

• One wire in (single entry point)
• One wire out (single output)
• Lots of internals between them

When to Chunk

Look for sections where tracing the wiring reveals a "pinch point" — many affordances that funnel through a single input and single output. These are natural boundaries for chunking.

Example: A dynamic-form component receives a form definition, renders many fields (U7a-U7k), validates on change (N26), and emits a single valid$ signal. In the main diagram, this becomes:

N24 -->|formDefinition| dynamicForm
dynamicForm -.->|valid$| U8

How to Chunk

1. In the main diagram, replace the subsystem with a single stadium-shaped node:

dynamicForm[["CHUNK: dynamic-form"]]

2. Wire to/from the chunk using the boundary signals:

N24 -->|formDefinition| dynamicForm
dynamicForm -.->|valid$| U8

3. Create a separate chunk diagram showing the internals with boundary markers:

flowchart TB
    input([formDefinition])
    output(["valid$"])

    subgraph chunk["dynamic-form internals"]
        N25["N25: generateFormConfig()"]
        U7a["U7a: field"]
        N26["N26: form value changes"]
        N27["N27: valid$ emission"]
    end

    input --> N25
    N25 --> U7a
    U7a --> N26
    N26 --> N27
    N27 --> output

    classDef boundary fill:#b3e5fc,stroke:#0288d1,stroke-dasharray:5 5
    class input,output boundary

4. Style chunks distinctly in the main diagram:

classDef chunk fill:#b3e5fc,stroke:#0288d1,color:#000,stroke-width:2px
class dynamicForm chunk

Chunk Color Convention

Benefits

• Main diagram stays readable — complex subsystems become single nodes
• Detail preserved — chunk diagrams show the internals when needed
• Natural boundaries — chunks often map to reusable components

Visualization (Mermaid)

The tables are the truth. Mermaid diagrams are optional visualizations for humans.

Basic Structure

flowchart TB
    U1["U1: search input"] --> N1["N1: activeQuery.next()"]
    N1 --> N2["N2: subscription"]
    N2 --> N3["N3: performSearch"]
    N3 --> N4["N4: searchOneCategory"]
    N4 -.-> N3
    N3 --> N5["N5: loading store"]
    N3 --> N6["N6: results store"]
    N5 -.-> U2["U2: loading spinner"]
    N6 -.-> U3["U3: results list"]

    classDef ui fill:#ffb6c1,stroke:#d87093,color:#000
    classDef nonui fill:#d3d3d3,stroke:#808080,color:#000
    class U1,U2,U3 ui
    class N1,N2,N3,N4,N5,N6 nonui

Line Conventions

Abbreviating Out-of-Scope Flows

When a data flow has intermediate steps that aren't relevant to the breadboard's scope, abbreviate by wiring directly from source to destination with a ... label:

S4 -.->|...| U6

This says "data flows from S4 to U6, with intermediate steps omitted." Use this when:

• The flow exists but its internals are out of scope
• You need to show where data originates without detailing the query chain
• The breadboard focuses on one workflow (e.g., editing) but needs to acknowledge another (e.g., viewing)

ID Prefixes

Color Conventions

classDef ui fill:#ffb6c1,stroke:#d87093,color:#000
classDef nonui fill:#d3d3d3,stroke:#808080,color:#000
classDef store fill:#e6e6fa,stroke:#9370db,color:#000
classDef chunk fill:#b3e5fc,stroke:#0288d1,color:#000,stroke-width:2px
classDef placeRef fill:#ffb6c1,stroke:#d87093,stroke-width:2px,stroke-dasharray:5 5

Subgraph Labels and Place IDs

Use the Place ID as the subgraph ID so navigation wiring connects properly:

flowchart TB
subgraph P1["P1: CMS Page (Read Mode)"]
    U1["U1: Edit button"]
    N1["N1: toggleEditMode()"]
end

subgraph P2["P2: CMS Page (Edit Mode)"]
    U2["U2: Save button"]
    U3["U3: Add button"]
end

%% Navigation wires to Place ID
N1 --> P2

Key point: The subgraph ID (P1, P2) must match the Place ID from the Places table. This allows navigation wires like N1 --> P2 to connect to the Place boundary.

When spanning multiple systems

flowchart TB
    subgraph frontend["SYSTEM: Frontend"]
        U1["U1: submit button"]
        N1["N1: handleSubmit()"]
    end

    subgraph backend["SYSTEM: Backend API"]
        N10["N10: POST /orders"]
        N11["N11: orderService.create()"]
    end

    U1 --> N1
    N1 --> N10
    N10 --> N11

Workflow Step Annotations (Optional)

When breadboarding a specific workflow, you can optionally add numbered step markers to help readers follow the sequence visually. This is useful when:

• The diagram is complex and the workflow path isn't obvious
• You want to guide someone through a specific user journey
• The breadboard will be used as a walkthrough or teaching tool

Format:

Add a Workflow Guide table before the diagram:

| Step | Action | Where to look |
|------|--------|---------------|
| **1** | Click "Edit" button | U1 → N1 → S1 |
| **2** | Edit mode activates | S1 → N2 → U3 |
| **3** | Click "Add" | U3 → N3 → N8 |

Add step marker nodes in the Mermaid diagram using stadium-shaped nodes:

flowchart TB
    %% Step markers
    step1(["1 - CLICK EDIT"])
    step2(["2 - EDIT MODE ON"])
    step3(["3 - CLICK ADD"])

    %% Connect steps to relevant affordances with dashed lines
    step1 -.-> U1
    step2 -.-> N2
    step3 -.-> U3

    %% Style step markers green
    classDef step fill:#90EE90,stroke:#228B22,color:#000,font-weight:bold
    class step1,step2,step3 step

Formatting notes:

• Use "1 - ACTION" format (number, space, hyphen, space, action)
• Avoid "1. ACTION" — the period triggers Mermaid's markdown list parser
• Avoid "1) ACTION" — parentheses can also cause parsing issues
• Connect step markers to affordances with dashed lines (-.->)
• Style steps green to distinguish from UI (pink) and Code (grey) affordances

Slicing a Breadboard

Slicing takes a breadboard and groups its affordances into vertical implementation slices. See Example B below for a complete slicing example.

Input:

• Breadboard (affordance tables with wiring)
• Shape (R + mechanisms) — guides what demos matter

Output:

• Breadboard with affordances assigned to slices V1–V9 (max 9 slices)

What is a Vertical Slice?

A vertical slice is a group of UI and Code affordances that does something demo-able. It cuts through all layers (UI, logic, data) to deliver a working increment.

The opposite is a horizontal slice — doing work on one layer (e.g., "set up all the data models") that isn't clickable from the interface.

The Key Constraint

Every slice must have visible UI that can be demoed. A slice without UI is a horizontal layer, not a vertical slice.

• ✅ "Self-serve Signing Path" (demo: checkout → sign → see signature)
• ❌ "Database Schema" (no demo possible)

Demo-able means:

• Has an entry point (UI interaction or trigger)
• Has an observable output (UI renders, effect occurs)
• Shows meaningful progress toward the R

The shape guides what counts as "meaningful progress" — you're not just grouping affordances arbitrarily, you're grouping them to demonstrate mechanisms working.

Slice Size

• Too small: Only 1-2 UI affordances, no meaningful demo → merge with related slice
• Too big: 15+ affordances or multiple unrelated journeys → split
• Right size: A coherent journey with a clear "watch me do this" demo

Aim for ≤9 slices. If you need more, the shape may be too large for one cycle.

Wires to Future Slices

A slice may contain affordances with Wires Out pointing to affordances in later slices. These wires exist in the breadboard but aren't implemented yet — they're stubs or no-ops until that later slice is built.

This is normal. The breadboard shows the complete system; slicing shows the order of implementation.

Procedure

Step 1: Identify the minimal demo-able increment

Look at your breadboard and shape. Ask: "What's the smallest subset that demonstrates the core mechanism working?"

Usually this is:

• The core data fetch
• Basic rendering
• No search, no pagination, no state persistence yet

This becomes V1.

Step 2: Layer additional capabilities as slices

Look at the mechanisms in your shape. Each slice should demonstrate a mechanism working:

• V2: Search input (demonstrates the search mechanism)
• V3: Pagination/infinite scroll (demonstrates the pagination mechanism)
• V4: URL state persistence (demonstrates the state preservation mechanism)
• etc.

Max 9 slices. If you have more, combine related mechanisms. Features that don't make sense alone should be in the same slice.

Step 3: Assign affordances to slices

Go through every affordance and assign it to the slice where it's first needed to demo that slice's mechanism:

Some affordances may have Wires Out to later slices — that's fine. They're implemented in their assigned slice; the wires just don't do anything yet.

Step 4: Create per-slice affordance tables

For each slice, extract just the affordances being added:

V2: Search Works

Step 5: Write a demo statement for each slice

Each slice needs a concrete demo that shows its mechanism working toward the R:

• V1: "Widget shows real data from the API"
• V2: "Type 'dharma', results filter live"
• V3: "Scroll down, more items load"

The demo should be something you can show a stakeholder that demonstrates progress.

Visualizing Slices in Mermaid

Show the complete breadboard in every slice diagram, but use styling to distinguish scope:

flowchart TB
    U1["U1: search input"]
    U2["U2: loading spinner"]
    N1["N1: activeQuery.next()"]
    N2["N2: subscription"]
    N3["N3: performSearch"]

    U1 --> N1
    N1 --> N2
    N2 --> N3
    N3 --> U2

    %% V2 scope (this slice) = green
    classDef thisSlice fill:#90EE90,stroke:#228B22,color:#000
    %% Already built (V1) = grey
    classDef built fill:#d3d3d3,stroke:#808080,color:#000
    %% Future = transparent dashed
    classDef future fill:none,stroke:#ddd,color:#bbb,stroke-dasharray:3 3

    class U1,N1,N2 thisSlice
    class U2,N3 built

This lets stakeholders see:

• What's being built now (highlighted)
• What already exists (grey)
• What's coming later (faded)

Slice Summary Format

The Mechanism column references parts from the shape, showing which mechanisms each slice demonstrates.

Examples

Example A: Mapping an Existing System

This example shows breadboarding an existing system to understand how data flows through multiple entry points.

Input

Workflow to understand: "How is admin_organisation_countries modified and read downstream? There are multiple entry points: manual edit, checkbox toggle, and batch job."

Output

UI Affordances

Code Affordances

Data Stores

Mermaid Diagram

flowchart TB
    subgraph stores["DATA STORES"]
        S1["S1: role_profiles"]
        S2["S2: admin_organisation_countries"]
        S3["S3: organisations"]
    end

    subgraph ssoAdmin["PLACE: SSO Admin — User Change Page"]
        subgraph permissions["Permissions fieldset"]
            U1["U1: role_profiles checkboxes"]
            U2["U2: 'Country Admin' checkbox"]
        end

        subgraph userAdmin["User admin fieldset (superuser only)"]
            U3["U3: admin_countries filter_horizontal"]
            U4["U4: Available countries"]
            U5["U5: Selected countries"]
            U6["U6: Add → / Remove ←"]
        end

        U7["U7: Save button"]
        N1["N1: get_fieldsets()"]
        N2["N2: get_administrable_user_countries()"]
        N3["N3: save_form()"]
        N4["N4: Form M2M save"]
        N5["N5: _update_user_m2m()"]
        N6["N6: user_m2m_field_updated signal"]

        N1 -->|is_superuser| userAdmin
        U3 --> U4
        U3 --> U5
        U6 --> U5
        N2 -.-> U4

        U2 --> U7
        U6 --> U7
        U7 --> N3
        N3 --> N4
        N3 --> N5
        N5 --> N6
    end

    subgraph trigger["TRIGGER: Batch Cleanup"]
        N7["N7: manage.py dwbn_cleanup"]
    end

    subgraph theme["sso-dwbn-theme"]
        N10["N10: dwbn_user_m2m_field_updated()"]
        N11["N11: dwbn_user_m2m_field_updated_task()"]
        N12["N12: Country Admin added AND zero admin countries?"]
        N15["N15: admin_changes()"]
        N16["N16: For each Country Admin: home center country missing?"]
        N20["N20: Get home center's country"]
        N21["N21: admin_organisation_countries.add()"]
        N22["N22: update_last_modified()"]

        N6 --> N10
        N10 --> N11
        N11 --> N12
        N7 --> N15
        N15 --> N16
        N12 -->|yes| N20
        N16 -->|yes| N20
        N20 --> N21
        N21 --> N22
    end

    subgraph dwconnect["PLACE: DWConnect — Center Page"]
        N30["N30: findCenterAdmins()"]
        U20["U20: 'Country admins' section"]

        N30 --> U20
    end

    subgraph api["TRIGGER: External API Request"]
        N31["N31: get_object_data()"]
    end

    U21["U21: System email 'From' field"]

    N4 --> S2
    N5 --> S1
    N21 --> S2
    S1 -.-> N15
    S3 -.-> N16
    S3 -.-> N20
    S2 -.-> U5
    S2 -.-> N30
    S2 -.-> N31
    S2 -.-> U21

    classDef ui fill:#ffb6c1,stroke:#d87093,color:#000
    classDef nonui fill:#d3d3d3,stroke:#808080,color:#000
    classDef store fill:#e6e6fa,stroke:#9370db,color:#000
    classDef condition fill:#fffacd,stroke:#daa520,color:#000
    classDef trigger fill:#98fb98,stroke:#228b22,color:#000

    class U1,U2,U3,U4,U5,U6,U7,U20,U21 ui
    class N1,N2,N3,N4,N5,N6,N10,N11,N15,N20,N21,N22,N30,N31 nonui
    class N12,N16 condition
    class N7 trigger
    class S1,S2,S3 store

Example B: Designing from Shaped Parts

Part 1: Shaping Context (Input to Breadboarding)

This section shows what comes FROM shaping — the requirements, existing patterns identified, and sketched parts. This is the INPUT that breadboarding receives.

Note: This example uses shaping terminology. In shaping, you define requirements (Rs), identify existing patterns to reuse, and sketch a solution as parts/mechanisms. Breadboarding takes this shaped solution and details out the concrete affordances and wiring.

The R (Requirements)

Existing System with Reusable Patterns (S-CUR)

The app already has a global search page that implements most of these Rs. During shaping, it was documented at the parts/mechanism level:

Sketched Solution: Parts that Adapt S-CUR

The new solution's parts explicitly reference which S-CUR patterns they adapt:

Part 2: Breadboarding (Transform Parts → Affordances)

This is where breadboarding happens. The shaped parts become concrete affordances with explicit wiring. The output is the affordance tables and diagram.

UI Affordances

Code Affordances

Mermaid Diagram

flowchart TB
    subgraph lettersIndex["PLACE: Letters Index Page"]
        subgraph letterBrowser["COMPONENT: letter-browser"]
            U1["U1: search input"]
            U2["U2: loading spinner"]
            U3["U3: no results msg"]
            U4["U4: result count"]
            U5["U5: results list"]
            U12["U12: See all X results"]

            N1["N1: activeQuery.next"]
            N2["N2: activeQuery sub"]
            N3["N3: performSearch"]
            N6["N6: loading store"]
            N7["N7: detailResult store"]
            N8["N8: detectChanges"]
            N10["N10: initializeState"]
            N16["N16: if truncated show link"]
            N5["N5: parentId (config)"]
            N17["N17: compact (config)"]
            N18["N18: fullPageRoute (config)"]

            subgraph pagination["PAGINATION"]
                U10["U10: scroll"]
                N15["N15: if !compact subscribe"]
                N12["N12: appendNextPage"]
            end
        end
    end

    subgraph letterRow["COMPONENT: letter-row"]
        U6["U6: row click"]
        U7["U7: date"]
        U8["U8: subject"]
        U9["U9: teaser"]
    end

    subgraph browser["BROWSER"]
        U11["U11: back button"]
        N9["N9: URL ?q="]
        N14["N14: Router.navigate"]
    end

    subgraph services["SERVICES"]
        N4["N4: rawSearch"]
        N11["N11: intercom subject"]
        N13["N13: sendMessage"]
    end

    subgraph letterDetail["PLACE: Letter Detail Page"]
        LD["Letter Detail"]
    end

    U1 -->|type| N1
    N1 --> N2
    N2 -->|debounce 90ms, min 3| N3

    N3 --> N4
    N3 --> N6
    N3 --> N7
    N3 --> N8

    N4 -.-> N3
    N4 -.-> N12
    N6 -.-> N8
    N7 -.-> N8

    N8 --> U2
    N8 --> U3
    N8 --> U4
    N8 --> U5

    U5 --> U6
    U5 --> U7
    U5 --> U8
    U5 --> U9

    U6 -->|navigate| LD
    U11 -->|restore| N9
    N9 --> N10
    N10 --> N1
    N10 --> N3

    U10 --> N11
    N15 -->|if !compact| N11
    N11 --> N12
    N12 --> N4
    N12 --> N7
    N12 --> N8
    N12 --> N13
    N12 --> N14
    N13 -->|re-arm| N11

    N5 -.->|filter| N4
    N17 -.-> N4
    N17 -.-> N15
    N17 -.-> N16
    N18 -.-> U12
    N14 -.->|URL| N9

    N1 -.-> U12
    N7 -.-> N16
    N16 -->|if truncated| U12
    U12 -->|navigate with ?q| LP["Full Page"]

    classDef ui fill:#ffb6c1,stroke:#d87093,color:#000
    classDef nonui fill:#d3d3d3,stroke:#808080,color:#000

    class U1,U2,U3,U4,U5,U6,U7,U8,U9,U10,U11,U12,LD,LP ui
    class N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18 nonui

Slicing the Breadboard

With the full breadboard complete, slice it into vertical increments. Each slice demonstrates a mechanism working:

Slice Summary

Slice Diagram

flowchart TB
    subgraph slice1["V1: WIDGET WITH REAL DATA"]
        U2["U2: loading spinner"]
        U3["U3: no results msg"]
        U4["U4: result count"]
        U5["U5: results list"]
        U6["U6: row click"]
        U7["U7: date"]
        U8["U8: subject"]
        U9["U9: teaser"]

        N3["N3: performSearch"]
        N4["N4: rawSearch"]
        N5["N5: parentId (config)"]
        N6["N6: loading store"]
        N7["N7: detailResult store"]
        N8["N8: detectChanges"]
        LD["Letter Detail"]
    end

    subgraph slice2["V2: SEARCH WORKS"]
        U1["U1: search input"]
        N1["N1: activeQuery.next"]
        N2["N2: activeQuery sub"]
    end

    subgraph slice3["V3: INFINITE SCROLL"]
        U10["U10: scroll"]
        N11["N11: intercom subject"]
        N12["N12: appendNextPage"]
        N13["N13: sendMessage"]
    end

    subgraph slice4["V4: URL STATE"]
        U11["U11: back button"]
        N9["N9: URL ?q="]
        N10["N10: initializeState"]
        N14["N14: Router.navigate"]
    end

    subgraph slice5["V5: COMPACT MODE"]
        U12["U12: See all X results"]
        N15["N15: if !compact subscribe"]
        N16["N16: if truncated show link"]
        N17["N17: compact (config)"]
        N18["N18: fullPageRoute (config)"]
        LP["Full Page"]
    end

    U1 -->|type| N1
    N1 --> N2
    N2 -->|debounce| N3

    N3 --> N4
    N3 --> N6
    N3 --> N7
    N3 --> N8
    N4 -.-> N3
    N5 -.->|filter| N4

    N6 -.-> N8
    N7 -.-> N8
    N8 --> U2
    N8 --> U3
    N8 --> U4
    N8 --> U5
    U5 --> U6
    U5 --> U7
    U5 --> U8
    U5 --> U9
    U6 -->|navigate| LD

    U11 -->|restore| N9
    N9 --> N10
    N10 --> N1
    N10 --> N3

    U10 --> N11
    N11 --> N12
    N12 --> N4
    N12 --> N7
    N12 --> N8
    N12 --> N13
    N12 --> N14
    N13 -->|re-arm| N11
    N4 -.-> N12
    N14 -.->|URL| N9

    N15 -->|if !compact| N11
    N17 -.-> N4
    N17 -.-> N15
    N17 -.-> N16
    N18 -.-> U12
    N1 -.-> U12
    N7 -.-> N16
    N16 -->|if truncated| U12
    U12 -->|navigate with ?q| LP

    style slice1 fill:#e8f5e9,stroke:#4caf50,stroke-width:2px
    style slice2 fill:#e3f2fd,stroke:#2196f3,stroke-width:2px
    style slice3 fill:#fff3e0,stroke:#ff9800,stroke-width:2px
    style slice4 fill:#f3e5f5,stroke:#9c27b0,stroke-width:2px
    style slice5 fill:#fff8e1,stroke:#ffc107,stroke-width:2px

    classDef ui fill:#ffb6c1,stroke:#d87093,color:#000
    classDef nonui fill:#d3d3d3,stroke:#808080,color:#000

    class U1,U2,U3,U4,U5,U6,U7,U8,U9,U10,U11,U12,LD,LP ui
    class N1,N2,N3,N4,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,N17,N18 nonui