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🧱 UI Strand – Slack

Visual patterns · Components · Design systems The UI Strand describes how the product looks and behaves on screen:
layouts, patterns, components, and the design system that keeps everything consistent. Here we use Slack as a concrete, fact-based example, based on its public brand guidelines, product UI, and Block Kit documentation.

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🧬 1. UI System Overview

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Brand vs. Product UI

  • Brand palette: expressive, vibrant colors (aubergine, blue, green, yellow, red, black, white) used for marketing and identity.
  • Product UI: more muted, accessible, low-fatigue colors that still echo the brand but prioritize usability and legibility over visual noise.

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Block Kit – App UI Framework

For apps and extensions inside Slack, the UI framework is:
  • Block Kit – a stackable UI framework for messages, Home tabs, and modals.
  • Built from:
    • Blocks – structural chunks (sections, images, actions, context, etc.).
    • Block elements – interactive components (buttons, selects, date pickers, etc.).
    • Composition objects – smaller building blocks like text objects and options.
  • Used for:
    • App messages
    • App Home surfaces
    • Modals / forms
    • Rich notifications and interactive flows

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🧩 2. Structural Building Blocks

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Core Layout Surfaces in Slack

Slack’s main product UI is organized around a small set of reusable layout surfaces:
  • Workspace Shell
    • Top app bar with workspace switcher, search, and quick actions.
  • Navigation Sidebar
    • Channels, direct messages, sections, and key views (e.g. Activity, Later, etc. depending on version).
  • Main Content Pane
    • Message timelines, threads, huddles, canvases, and app content.
  • Secondary Panels
    • Thread details, profiles, canvas details, app drawers that slide in from the right.
  • Global Overlays
    • Modals, dialogs, pickers (channel picker, time picker, file upload, etc.).

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Block Kit Surfaces

For apps and workflows, Block Kit defines specific surfaces:
  • Messages
    • Rich, interactive messages in channels and DMs, built from up to a defined limit of blocks.
  • Modals
    • Structured dialogs for forms, confirmations, and multi-step workflows.
  • App Home
    • A customizable “app dashboard” inside Slack, composed completely of blocks.
Each surface type has layout constraints (max blocks, supported elements) that enforce consistency and prevent chaotic UI.

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🧱 3. Block Kit Components & Patterns

Blocks

High-level structural units like section, header, divider, image, actions, and context. They define the vertical flow and hierarchy of messages, modals, and app surfaces.

Block Elements

Interactive controls such as buttons, select menus, checkboxes, radio buttons, date pickers, and more. These live inside blocks and drive app interactivity.

Composition Objects

Smaller objects (like text objects, option objects, confirm dialogs) that consistently shape content and behavior across blocks.

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Common UI Patterns Enabled by Block Kit

  • Action rows – buttons and menus grouped in an actions block.
  • Card-like messages – section + image + context blocks mimicking a card layout.
  • Forms in modals – input elements stacked vertically with clear labels and helper text.
  • Dashboards in App Home – repeated sections with metrics, filters, and actions.
  • Rich notifications – compact messages with primary action buttons and secondary info.

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🎨 4. Visual Language in the Product UI

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Color System in the App

Slack’s product UI color usage follows a few core rules:
  • Neutral canvas – grays and soft surfaces for main backgrounds to reduce fatigue.
  • Branded accents – Slack colors (especially aubergine, blues, greens, yellows) used for:
    • highlights
    • buttons
    • badges / statuses
    • selection states
  • Semantic colors – greens for “success”, reds for “errors/alerts”, yellows for “warnings”, tuned for contrast and accessibility.

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Typography

Slack’s visual identity uses:
  • Larsseit and Slack Circular (or similar fallbacks) in marketing and product surfaces.
  • Type roles:
    • Headlines / primary labels – bold, clean, and high-contrast.
    • Body copy / messages – highly legible at small sizes for long-form chat content.
    • Metadata / timestamps – de-emphasized but readable, often with lighter weight or smaller size.

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Iconography & Shape Language

  • Rounded shapes – pill buttons, circular avatars, soft cards.
  • Octothorpe heritage – the Slack logo and key UI metaphors reference the # symbol (channels, hashtags).
  • Simple, vector icons – minimal, clear metaphors, optimized for small sizes and dense environments.

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🧠 5. Interaction & State Patterns

Slack’s UI patterns are built around real-time, conversational work:

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Interaction Principles

  • Inline First
    • Most actions (reactions, replies, file previews) happen inline without leaving the channel.
  • Progressive Disclosure
    • Threads, canvases, user profiles, and app details open in side panels or overlays instead of full page navigations.
  • Non-blocking Modals
    • Forms and confirmations appear in modals with clear primary/secondary actions, and safe exits.

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State Handling

  • Read vs Unread
    • Channels and messages use clear typographic and color cues (bold labels, badges) to signal unread activity.
  • Hover & Focus States
    • Message rows and interactive elements show subtle hover/focus affordances to clarify click targets.
  • Error & Confirmation States
    • Errors are communicated near the control that caused the issue, with clear, human-readable messaging.
  • Ephemeral vs Persistent
    • Ephemeral messages and transient prompts are visually differentiated from persistent content.

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♿ 6. Accessibility & Content Rules

Slack’s UI and Block Kit guidelines emphasize:

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Content Rules

  • Clear and concise copy – especially in buttons, labels, and block text.
  • Avoid over-loading blocks – use hierarchy and whitespace so content is scannable.
  • Consistent wording – reuse terminology and patterns across workflows.

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Accessibility Practices

  • Color contrast – brand and UI colors are checked for accessible combinations in text and backgrounds.
  • Structured layouts – blocks and elements are ordered logically for assistive technologies.
  • Descriptive labels – interactive components have clear labels and alt text where needed.
  • Keyboard-friendly interactions – modals and controls are designed to work without a mouse.

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🧰 7. Design System Assets & Tools

Slack Brand Center

Central hub for logos, color, typography, illustration, and writing guidelines. This is the source of truth for visual identity used across product and marketing.

Block Kit Docs

Developer and designer documentation for Slack’s in-product UI framework — blocks, elements, patterns, and best practices for messages, modals, and App Home.

Block Kit Builder

Web-based WYSIWYG editor for constructing Block Kit layouts, used for prototyping and sharing UI patterns before implementation.

Figma Kits & UI Libraries

Community and internal Figma resources replicating Slack UI shells and Block Kit components, used to design workflows and app extensions visually.

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✅ UI Strand Summary – Slack

{
  "ui_strand": {
    "workshop_meta": {
      "framework_version": "ui-strand-v1.0",
      "source_templates": [
        "UI Purpose & Role",
        "Platforms & Viewports",
        "Layout & Navigation",
        "Components & Patterns",
        "Design Tokens",
        "Visual Language",
        "Interactions & States",
        "Accessibility",
        "Design System Assets",
        "Governance & Quality"
      ],
      "facilitation_notes": [
        "Run with product design, design systems, front-end engineering, and accessibility.",
        "Start with screenshots / flows of real product; reverse-engineer structure into this JSON.",
        "Treat this as the single source of truth for UI decisions and component behavior."
      ]
    },

    "purpose_and_role": {
      "question": "What is the role of UI in this product?",
      "answer": "The UI exists to make complex, multi-party work feel simple, navigable and predictable. It should visually express the brand, guide users through workflows with minimal friction, and support fast comprehension of dense information.",
      "objectives": [
        "Reduce cognitive load in dense, real-time collaboration contexts.",
        "Make key actions and information visually obvious without overwhelming the user.",
        "Align visual language with brand while prioritizing usability and accessibility."
      ]
    },

    "platforms_and_viewports": {
      "question": "Where does our UI live, and what environments must it support?",
      "platforms": [
        {
          "name": "Desktop Web",
          "primary_viewports": ["1440x900", "1280x720"],
          "notes": "Primary environment; most features are optimized for multi-column layouts."
        },
        {
          "name": "Mobile",
          "primary_viewports": ["375x812", "414x896"],
          "notes": "Condensed navigation; focuses on critical workflows and consumption."
        },
        {
          "name": "Desktop App",
          "primary_viewports": ["Responsive to window size"],
          "notes": "Shell mirrors web UI but integrates OS-level capabilities (notifications, shortcuts)."
        }
      ],
      "cross_platform_principles": [
        "Core patterns (navigation, hierarchy, semantics) remain consistent across platforms.",
        "Mobile adapts UI density and interaction targets but keeps mental models aligned."
      ]
    },

    "layout_system": {
      "question": "What are the core layout regions and how do they behave?",
      "primary_surfaces": [
        {
          "name": "App Shell",
          "description": "Top-level frame containing global navigation, search, account controls.",
          "rules": [
            "Always visible; acts as anchor for orientation.",
            "Hosts global actions (search, create, notifications)."
          ]
        },
        {
          "name": "Navigation Sidebar",
          "description": "Left column listing workspaces, sections, and primary destinations.",
          "rules": [
            "Uses vertical lists and grouping for scalable navigation.",
            "Indicates unread / active states via typography and badges."
          ]
        },
        {
          "name": "Main Content",
          "description": "Central area for primary content: timelines, documents, or workspaces.",
          "rules": [
            "One primary focus at a time; avoid nested scroll containers.",
            "Supports contextual toolbars and inline actions."
          ]
        },
        {
          "name": "Secondary Panel",
          "description": "Right-hand contextual panel for details, threads, or inspectors.",
          "rules": [
            "Slides in without fully obscuring main content.",
            "Used for details that deepen context, not new primary tasks."
          ]
        },
        {
          "name": "Overlays & Modals",
          "description": "Dialogs, pickers, forms and confirmations.",
          "rules": [
            "Block background interaction when a decision is required.",
            "Always provide safe exits and clear primary/secondary actions."
          ]
        }
      ],
      "grid_system": {
        "columns": 12,
        "gutter_px": 24,
        "margin_px": 24,
        "notes": "Desktop layouts adhere to a 12-column grid; mobile uses 4–6 columns for simplicity."
      }
    },

    "navigation_patterns": {
      "question": "How do users move through the product?",
      "global_navigation": [
        "Persistent left sidebar with sections and collapsible groups.",
        "Top-level search that can jump to people, spaces, and content.",
        "Keyboard shortcuts for frequent navigation actions."
      ],
      "local_navigation": [
        "Tabs within a single surface to switch between closely related views.",
        "Secondary panels for related but non-primary information.",
        "Breadcrumbs where deep hierarchical navigation exists."
      ],
      "discovery_mechanisms": [
        "Contextual menus on hover or long-press for advanced actions.",
        "Empty states introducing key concepts and primary actions.",
        "Onboarding tooltips for first-time feature discovery."
      ]
    },

    "components_and_patterns": {
      "primitive_components": [
        "Buttons (primary, secondary, tertiary, destructive)",
        "Text inputs, textareas, search fields",
        "Selects, dropdowns, comboboxes",
        "Checkboxes, radio buttons, switches",
        "Avatars, badges, tags, chips",
        "Icons, spinners, progress indicators"
      ],
      "composite_components": [
        "Toolbars and action bars",
        "Cards and list rows",
        "Data tables and item lists",
        "Message bubbles or content blocks",
        "Navigation lists and sidebars",
        "Notification toasts and banners"
      ],
      "interaction_patterns": [
        "Inline editing of items in lists where appropriate.",
        "Hover- or focus-revealed quick actions on list rows.",
        "Confirmation dialogs for destructive actions.",
        "Undo snackbar for reversible changes.",
        "Progressive disclosure: show advanced settings behind a 'More options' affordance."
      ],
      "block_based_framework": {
        "question": "Do we have a block/section based framework (like Slack’s Block Kit)?",
        "answer": "Yes/No (define here)",
        "notes": "If yes, define block types, elements, and composition rules in a separate object."
      }
    },

    "design_tokens": {
      "question": "What are the atomic UI decisions the entire system depends on?",
      "color": {
        "primitive_tokens": [
          { "name": "color.background.default", "value": "#FFFFFF" },
          { "name": "color.text.primary", "value": "#1D1D1F" },
          { "name": "color.accent.primary", "value": "#611F69" },
          { "name": "color.border.subtle", "value": "#DDDDDD" }
        ],
        "semantic_tokens": [
          { "name": "color.text.muted", "maps_to": "color.text.primary", "opacity": 0.64 },
          { "name": "color.bg.elevated", "maps_to": "color.background.default", "elevation": "level1" },
          { "name": "color.status.success", "maps_to": "color.green.500" },
          { "name": "color.status.error", "maps_to": "color.red.500" }
        ]
      },
      "typography": {
        "scales": [
          { "name": "text.xs", "size_px": 12, "line_height": 16 },
          { "name": "text.sm", "size_px": 14, "line_height": 20 },
          { "name": "text.md", "size_px": 16, "line_height": 24 },
          { "name": "text.lg", "size_px": 20, "line_height": 28 }
        ],
        "roles": [
          { "role": "body", "token": "text.md" },
          { "role": "caption", "token": "text.xs" },
          { "role": "heading_sm", "token": "text.lg", "weight": "600" }
        ]
      },
      "spacing": {
        "scale": [0, 4, 8, 12, 16, 20, 24, 32],
        "notes": "All component paddings, margins, and gaps should derive from these units."
      },
      "radius": {
        "tokens": [
          { "name": "radius.none", "value": 0 },
          { "name": "radius.sm", "value": 4 },
          { "name": "radius.md", "value": 8 },
          { "name": "radius.lg", "value": 16 }
        ]
      },
      "elevation": {
        "tokens": [
          { "name": "shadow.none", "value": "none" },
          { "name": "shadow.level1", "value": "0 1px 3px rgba(0,0,0,0.12)" },
          { "name": "shadow.level2", "value": "0 4px 12px rgba(0,0,0,0.18)" }
        ]
      },
      "motion": {
        "tokens": [
          { "name": "duration.fast", "value": "120ms" },
          { "name": "duration.normal", "value": "180ms" },
          { "name": "duration.slow", "value": "240ms" },
          { "name": "easing.standard", "value": "cubic-bezier(0.4, 0.0, 0.2, 1)" }
        ],
        "principles": [
          "Motion should serve comprehension, not decoration.",
          "Animations should be subtle, fast, and cancelable."
        ]
      }
    },

    "visual_language": {
      "color_usage": {
        "principles": [
          "Use neutrals for backgrounds and layouts; reserve strong brand colors for emphasis and actions.",
          "Semantic colors (success, warning, error, info) must remain consistent across all surfaces.",
          "Avoid using color alone to convey meaning; pair with icons or labels."
        ],
        "examples": [
          "Primary actions use the main accent color with high contrast text.",
          "Informational banners use a subtle tint with an icon and clear label."
        ]
      },
      "typography_roles": {
        "principles": [
          "Body text must remain highly legible at the smallest supported size.",
          "Headings establish hierarchy but should not visually compete with content.",
          "Metadata (timestamps, helper text) is visually de-emphasized but still readable."
        ]
      },
      "iconography": {
        "styles": [
          "Simple, geometric icons with consistent stroke weight.",
          "Minimal detail for clarity at small sizes.",
          "Avoid overly playful or metaphorical icons that obscure meaning."
        ],
        "usage_rules": [
          "Icons accompany labels, not replace them for critical actions.",
          "Status icons use semantic color coding consistently."
        ]
      },
      "shape_language": {
        "guidelines": [
          "Rounded corners to reinforce approachability.",
          "Avoid sharp or aggressive shapes in primary interaction zones.",
          "Use overlapping shapes and stacked layers to imply collaboration and depth."
        ]
      },
      "imagery": {
        "style": [
          "Human-centric imagery showing real or stylized collaboration.",
          "Avoid generic corporate stock where possible.",
          "Illustrations should simplify, not complicate, conceptual explanations."
        ]
      }
    },

    "interaction_and_states": {
      "interaction_principles": [
        "Inline interactions where possible to reduce context switching.",
        "Progressive disclosure for complexity — show essentials by default.",
        "Respect the user’s focus: avoid unexpected modal interrupts."
      ],
      "core_states": [
        "Default",
        "Hover / Focus",
        "Active / Pressed",
        "Loading",
        "Disabled",
        "Success",
        "Warning",
        "Error"
      ],
      "feedback_patterns": [
        "Use inline validation for forms with clear, human-readable messages.",
        "Show non-blocking toasts for background operations and recovery actions.",
        "Use spinners or skeletons for loading states that exceed a defined threshold."
      ],
      "keyboard_and_shortcuts": {
        "support_level": "first-class",
        "principles": [
          "All primary actions must be reachable via keyboard.",
          "Global and contextual shortcuts should be discoverable and documented.",
          "Focus order respects visual hierarchy and user expectations."
        ]
      }
    },

    "accessibility": {
      "policies": [
        "Target WCAG 2.1 AA or higher for contrast and interaction.",
        "All interactive controls must have accessible names and roles.",
        "Support screen readers across primary platforms."
      ],
      "checklist": [
        "Color contrast: text and icons meet contrast standards.",
        "Keyboard navigation: all interactive elements focusable and operable.",
        "Focus indicators: visible and distinct.",
        "ARIA attributes used appropriately where semantics are not native.",
        "Motion and animation respect reduced motion user preferences."
      ]
    },

    "theming_and_modes": {
      "supports_dark_mode": true,
      "theming_model": "semantic-tokens",
      "rules": [
        "Semantic tokens remain constant; underlying raw values change by theme.",
        "Preserve brand recognition across themes without sacrificing legibility.",
        "Check all theme combinations for critical workflows before release."
      ]
    },

    "design_system_assets": {
      "figma_libraries": [
        {
          "name": "Core UI Library",
          "scope": "Tokens, primitives, common patterns",
          "owner": "Design Systems Team"
        },
        {
          "name": "Product Surfaces",
          "scope": "Shell, navigation, high-level layouts per platform",
          "owner": "Product Design"
        }
      ],
      "code_libraries": [
        {
          "name": "UI Component Library",
          "tech_stack": "React / TypeScript",
          "owner": "Front-end Platform"
        }
      ],
      "documentation": [
        {
          "type": "UI Guidelines",
          "location": "internal-docs/ui",
          "notes": "Usage guidelines, anti-patterns, accessibility notes."
        }
      ],
      "tools": [
        "Design handoff tool of choice (e.g., Figma Inspect, Storybook, etc.)",
        "Visual regression testing suite",
        "Linting rules for UI code consistency"
      ]
    },

    "governance_and_quality": {
      "ownership": {
        "primary_owner": "Design Systems Lead",
        "co_owners": [
          "Head of Product Design",
          "Front-end Platform Lead",
          "Accessibility Lead"
        ]
      },
      "change_process": [
        "Propose change in design system RFC channel.",
        "Prototype in Figma and/or UI sandbox.",
        "Review with design systems + accessibility + engineering.",
        "Document rationale and usage guidelines.",
        "Implement in code library and announce to product teams."
      ],
      "quality_metrics": [
        "Design system adoption rate (% of UI built using system components).",
        "Number of custom one-off components in production (lower is better).",
        "Accessibility issue count and resolution time.",
        "Visual regression failures per release.",
        "Support tickets attributable to confusing or broken UI."
      ]
    },

    "ui_archetype": {
      "question": "If the UI were a character, how should it feel?",
      "primary_archetype": "Guide",
      "secondary_archetype": "Collaborator",
      "rationale": "The UI should feel like a calm, competent partner that helps users navigate complexity and coordinate with others, not like a control panel or a chaotic feed."
    }
  }
}