Opendevbrowser Design Agent

Design Agent Skill

Use this skill for frontend work that must be visually strong, contract-first, and verified in a real browser instead of judged only from code.

Pack Contents

• artifacts/design-workflows.md
• artifacts/design-contract-playbook.md
• artifacts/design-agent-work-products.md
• artifacts/frontend-evaluation-rubric.md
• artifacts/external-pattern-synthesis.md
• artifacts/component-pattern-index.md
• artifacts/existing-surface-adaptation.md
• artifacts/app-shell-and-state-wiring.md
• artifacts/state-ownership-matrix.md
• artifacts/async-search-state-ownership.md
• artifacts/loading-and-feedback-surfaces.md
• artifacts/theming-and-token-ownership.md
• artifacts/isolated-preview-validation.md
• artifacts/performance-audit-playbook.md
• artifacts/scroll-reveal-surface-planning.md
• artifacts/research-harvest-workflow.md
• artifacts/design-release-gate.md
• artifacts/opendevbrowser-ui-example-map.md
• artifacts/implementation-anti-patterns.md
• assets/templates/design-brief.v1.md
• assets/templates/design-audit-report.v1.md
• assets/templates/design-contract.v1.json
• assets/templates/canvas-generation-plan.design.v1.json
• assets/templates/canvas-patch.request.v1.json
• assets/templates/inspiredesign-advanced-brief.v1.json
• assets/templates/design-review-checklist.json
• assets/templates/real-surface-design-matrix.json
• assets/templates/reference-pattern-board.v1.json
• assets/templates/design-release-gate.v1.json
• scripts/design-workflow.sh
• scripts/extract-canvas-plan.sh
• scripts/validate-skill-assets.sh
• Motion authority: ../opendevbrowser-motion-design/SKILL.md
• Shared robustness matrix: ../opendevbrowser-best-practices/artifacts/browser-agent-known-issues-matrix.md
• Shared canvas workflow baseline: ../opendevbrowser-best-practices/SKILL.md

Quick Start

1. Validate pack integrity.

./skills/opendevbrowser-design-agent/scripts/validate-skill-assets.sh

2. Print a workflow.

./skills/opendevbrowser-design-agent/scripts/design-workflow.sh contract-first
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh canvas-contract
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh real-surface-validation
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh research-harvest
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh release-gate
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh performance-audit

3. Convert a full design contract into a /canvas-ready generation plan.

./skills/opendevbrowser-design-agent/scripts/extract-canvas-plan.sh \
  skills/opendevbrowser-design-agent/assets/templates/design-contract.v1.json

Supporting Surfaces

• Keep generated-help labels exact when referencing cross-pack capabilities: screencast / browser replay, desktop observation, and computer use / browser-scoped computer use.
• Use browser replay (screencast-start / screencast-stop) during real-surface validation when motion, sequencing, or transition timing matters.
• Load opendevbrowser-motion-design when motion-heavy work needs terminology, pattern catalog decisions, platform/framework policy, device posture, reduced-motion rules, performance budgets, or temporal proof.
• Treat shader, WebGL, Spline-style, and custom 3D motion references as advisory cues unless current runtime evidence proves support.
• Desktop observation stays read-only and is only for external window or OS-level evidence around the workflow; it is not a design-surface control lane.
• Browser-scoped computer use remains a challenge posture knob via --challenge-automation-mode, not a desktop-agent capability.

Core Rules

• Start with a design contract, not ad-hoc implementation.
• Build a reference pattern board before locking a new direction when external inspiration matters; treat nextStepGuidance.readiness as recovery or continuation guidance only, and treat a harvest as design-ready only when top-level ready=true, productSuccess=true, artifactAuthority=product_ready, non-diagnostic evidenceAuthority, and manifest-backed reference evidence agree. For canonical Pinterest pin-media harvests, require evidenceAuthority=pin_media_ready and manifest-backed pin-media-index.json; snapshot_ready and motion_ready are not substitutes for pin-media readiness.
• Choose a component family from artifacts/component-pattern-index.md before inventing a new screen structure.
• Start from the closest shipped OpenDevBrowser example in artifacts/opendevbrowser-ui-example-map.md when the repo already has a related surface.
• Route repo-first redesigns through artifacts/existing-surface-adaptation.md before changing shells or component anatomy.
• Decide state ownership before writing component APIs, prompts, or /canvas patches.
• Declare app-shell, route, and overlay ownership with artifacts/app-shell-and-state-wiring.md before expanding navigation chrome or shared panels.
• Declare navigation and deep-link ownership in the contract before buttons, tabs, or search params start pushing route changes ad hoc.
• Declare async and search ownership with artifacts/async-search-state-ownership.md before wiring input-driven fetches, scopes, or background refresh.
• Keep one semantic token source with artifacts/theming-and-token-ownership.md; do not let leaf components invent raw colors, spacing, or type rules ad hoc.
• Define layout-preserving loading, empty/error recovery, and transient feedback surfaces with artifacts/loading-and-feedback-surfaces.md before polishing the happy path.
• For scan-heavy screens, declare list identity, lazy-loading, and progressive-reveal posture before polishing individual cards or rows.
• Keep one visual direction per task. Do not mix unrelated design languages.
• Prefer real content, realistic states, and explicit user journeys over placeholder copy.
• Preserve the repo's existing design system when one already exists. Only introduce a new direction when the brief or product gap justifies it.
• Treat /canvas governance as the strongest contract in the repo: read the handshake, respect generationPlanRequirements, inspect typed repair examples, and do not mutate before the plan is accepted.
• Treat preflightState="handshake_read" as the required ready state for the first post-open decision loop unless the handshake is already reporting an invalid-plan repair path.
• Keep durable design-agent work products under .opendevbrowser/design-agent/<run-id>/; use .tmp/ only for disposable command params, extractor output, and scratch responses.
• Preserve Canvas document persistence through canvas.document.save under .opendevbrowser/canvas/...; do not replace it with design-agent work-product storage.
• For non-canvas frontend work, still fill the same design-contract fields before coding so decisions stay consistent across code, preview, and docs.
• Use one owner for overlays, drawers, sheets, and detail panels; prefer item-backed state over boolean sprawl.
• If motion depends on scroll or viewport progress, define the driver and reduced-motion fallback before implementation.
• For animation systems, route the motion-specific decisions through ../opendevbrowser-motion-design/artifacts/motion-pattern-catalog.md, ../opendevbrowser-motion-design/artifacts/platform-framework-guide.md, ../opendevbrowser-motion-design/artifacts/performance-frame-budget.md, and ../opendevbrowser-motion-design/artifacts/open-dev-browser-motion-evidence.md.
• Carry advanced motion cues through designVectors and motionSystem as design intent only; they do not authorize new runtime libraries.
• Keep libraryPolicy.motion and libraryPolicy.threeD empty in samples unless a separate runtime change explicitly approves those lanes.
• Use artifacts/scroll-reveal-surface-planning.md whenever the design depends on pinned sections, reveal stages, or viewport-driven sequencing.
• Validate new patterns in isolation or /canvas preview with artifacts/isolated-preview-validation.md, including deterministic fixtures and installed dependencies, before declaring the integrated screen finished.
• Verify default, hover, focus, empty, loading, success, and error states when they are relevant.
• Validate responsive behavior intentionally; do not assume desktop layouts scale down cleanly.
• If the UI feels slow or unstable, switch to artifacts/performance-audit-playbook.md and capture a baseline before changing structure.
• Use OpenDevBrowser CLI for real-browser validation, not just static reasoning.
• Record the final ship decision in assets/templates/design-release-gate.v1.json; if evidence is missing, the task is not done.
• Finish by updating docs, AGENTS guidance, and any skill-pack references affected by the new UI behavior.

Design Contract

The mandatory design contract lives in assets/templates/design-contract.v1.json.

Every design task should answer these blocks before implementation:

• intent
• designLanguage
• contentModel
• navigationModel
• asyncModel
• layoutSystem
• typographySystem
• motionSystem
• performanceModel
• responsiveSystem
• accessibilityPolicy
• generationPlan

/canvas Required Generation Plan Fields

The generationPlan block must include:

• targetOutcome
• visualDirection
• layoutStrategy
• contentStrategy
• componentStrategy
• motionPosture
• responsivePosture
• accessibilityPosture
• validationTargets

Optional designVectors may carry advanced motion advisories, but it must not change the required CanvasGenerationPlan fields or imply shader, WebGL, Spline, or 3D runtime support.

Use scripts/extract-canvas-plan.sh when the full contract already exists and only the /canvas payload is needed. The extracted request is a command payload, not the durable source of truth. Keep the filled full contract in .opendevbrowser/design-agent/<run-id>/design-contract.json and use .tmp/canvas-plan.request.json for scratch submission.

Recommended Workflow Modes

contract-first

Use when starting from a brief or existing product requirement.

• Fill assets/templates/design-brief.v1.md.
• Translate it into assets/templates/design-contract.v1.json.
• Check artifacts/opendevbrowser-ui-example-map.md and artifacts/app-shell-and-state-wiring.md before deciding the shell structure.
• If a nearby shipped surface exists, review artifacts/existing-surface-adaptation.md before changing shell or component structure.
• Review artifacts/design-contract-playbook.md and artifacts/design-agent-work-products.md.
• Implement only after the contract is coherent.

research-harvest

Use when a redesign needs external references or when the brief explicitly asks for competitive learning.

• Start with artifacts/research-harvest-workflow.md.
• Capture 3 to 5 live references with OpenDevBrowser.
• For Pinterest, use the browser-native social/pinterest recipe with extension mode and cookies instead of treating Pinterest as a default full provider.
• Before extension-mode Pinterest harvests, preflight npx opendevbrowser status --daemon --output-format json and continue only when data.fingerprintCurrent === true, data.relay.extensionConnected === true, and data.relay.extensionHandshakeComplete === true.
• Inspect top-level ready, productSuccess, artifactAuthority, evidenceAuthority, and manifest-backed ranked reference evidence before using the bundle; use nextStepGuidance.readiness, nextStepGuidance.doNotProceedIf, and recovery commands only as follow-through or recovery guidance. For canonical Pinterest pin-media harvests, continue only with top-level ready=true, productSuccess=true, artifactAuthority=product_ready, evidenceAuthority=pin_media_ready, and manifest-backed pin-media-index.json; this is pin-media-first readiness, not screenshot or motion substitution.
• Record ready evidence in assets/templates/reference-pattern-board.v1.json.
• Turn the synthesis into contract deltas before implementation.

screenshot-audit

Use when starting from screenshots, mocks, or an existing page.

• Decompose the design into layout, type, spacing, state, motion, and accessibility decisions.
• Rewrite those observations into the same contract fields used for /canvas.
• Record issues and fixes in assets/templates/design-audit-report.v1.md.
• Use artifacts/frontend-evaluation-rubric.md before editing code.
• If the screen uses scroll-driven sequencing, add artifacts/scroll-reveal-surface-planning.md to the audit inputs.

canvas-contract

Use when the task should run through the design canvas.

• Start by creating .tmp/ and .opendevbrowser/design-agent/<run-id>/.
• Copy assets/templates/design-contract.v1.json into .opendevbrowser/design-agent/<run-id>/design-contract.json, then fill the full contract before extraction.
• Use artifacts/design-contract-playbook.md for section construction guidance and artifacts/design-agent-work-products.md for durable run files.
• Start with canvas.session.open; use canvas.capabilities.get only after you have a canvasSessionId.
• Use --output-format json for Canvas CLI commands whenever you read returned IDs, statuses, guidance, or follow-up fields.
• Read the handshake and inspect planStatus, preflightState, generationPlanRequirements.allowedValues, generationPlanIssues, guidance.recommendedNextCommands, guidance.nextStepGuidance, params examples, field examples, validation checks, and do-not-proceed blockers before choosing the next command.
• Treat preflightState="handshake_read" as the normal first-step checkpoint before canvas.plan.set; if the handshake already reports plan_invalid, repair the plan instead of mutating.
• Extract the generation plan to .tmp/canvas-plan.request.json after session open by passing .tmp/canvas-session.open.json to scripts/extract-canvas-plan.sh; .tmp is scratch-only.
• Submit canvas.plan.set --params-file .tmp/canvas-plan.request.json.
• If canvas.plan.set succeeds with planStatus="accepted" or preflightState="plan_accepted", copy the accepted plan request into .opendevbrowser/design-agent/<run-id>/canvas-plan.request.json and follow the returned guidance.recommendedNextCommands.
• Keep Canvas preview projection on canvas_html by default. Use bound_app_runtime only after runtime bridge preflight proves the bound app is reachable, intentional, and part of the accepted validation plan.
• Copy assets/templates/canvas-patch.request.v1.json to .tmp/canvas-patch.request.json, then fill accepted canvasSessionId, leaseId, latest numeric baseRevision, page IDs, node IDs, and token placeholders before mutation.
• If canvas.plan.set fails with generation_plan_invalid, inspect details.missingFields, details.issues, guidance.paramsExamples, guidance.fieldExamples, guidance.validationChecks, guidance.doNotProceedIf, and generationPlanIssues, then repair and resubmit the params file. Use canvas.plan.get or canvas.capabilities.get only when diagnostics are still needed after reading repair examples.
• Inspect canvas.starter.list before hand-authoring common dashboard, auth, marketing, settings, or docs shells when the requested design resembles a starter. Starter use is advisory and must be rejected when it does not satisfy the design contract.
• Use canvas.starter.apply only when a starter fits the contract; inspect or align any starter-seeded plan before further mutation.
• For multi-agent or multi-section design reviews, use canvas.workspace.open, canvas.workspace.status, canvas.workspace.child.add, canvas.workspace.child.execute, canvas.workspace.child.close, and canvas.workspace.close only after each child has a normal canvas session. Treat the workspace manifest as refs-only orchestration; child documents, leases, code-sync bindings, previews, and feedback remain child-owned. Do not route nested workspace commands or mutate sibling children; each child owns its document state and accepted plan.
• Call canvas.inventory.list after plan acceptance when reusable sections or components might fit. Use canvas.inventory.insert only with an accepted plan, current lease, page, parent, placement, and latest revision.
• Mutate with canvas.document.patch --params-file .tmp/canvas-patch.request.json, then copy the exact submitted patch into .opendevbrowser/design-agent/<run-id>/canvas-patch.request.json.
• Treat assets/templates/canvas-patch.request.v1.json as a minimal mutation smoke payload. Before canvas.document.save or canvas.document.export with exportTarget="design_document", patch every requiredBeforeSave governance block reported by the handshake or policy warnings.
• After every successful canvas.document.patch, canvas.preview.render, canvas.preview.refresh, canvas.feedback.poll, canvas.document.save, or canvas.document.export, read guidance.recommendedNextCommands and guidance.reason before choosing the next step.
• Validate extension-stage history controls against public canvas.history.undo and canvas.history.redo; design-tab clicks emit the internal canvas_history_requested event, but acceptance is still on the public command outcomes.
• When token work is in scope, validate collection or mode authoring, token value or alias edits, selected-node binding, and token usage inspection in the extension stage.
• If annotation send is part of the workflow, record whether the design tab returned Delivered to agent or Stored only; fetch with annotate --stored. Stored retrieval should expect Annotation V2 compact handoff with screenshot-free shared inbox storage, schemaVersion: 2, redaction metadata, selector bundles, and canvas identity when available; annotate --stored checks the shared repo-local inbox before extension-local fallback.
• Use canvas.preview.render, canvas.feedback.poll, canvas.preview.refresh, canvas.document.save, and canvas.document.export as the validation and persistence loop. If canvas.feedback.poll returns a preflight-blocker, return to canvas.plan.set before continuing.
• Remember that saved Canvas documents live under .opendevbrowser/canvas/...; .opendevbrowser/design-agent/<run-id>/ only stores planning, request, evidence, and handoff files.

real-surface-validation

Use when design work must be proven on live surfaces.

• Validate the design on the actual browser surface with snapshot, screenshot, debug-trace-snapshot, and relevant /canvas preview commands.
• Run artifacts/isolated-preview-validation.md first when the component family or state matrix is still unstable.
• Run the same real task across supported modes when parity is part of the acceptance criteria.
• Record blockers explicitly instead of hand-waving them away.

performance-audit

Use when the design feels heavy, re-renders too often, or becomes unstable with realistic content.

• Capture the slow interaction and baseline with artifacts/performance-audit-playbook.md.
• Use assets/templates/design-audit-report.v1.md to record issue / evidence / fix / validation.
• Prefer ownership and structure fixes before memoization or micro-optimizations.
• If scroll-driven motion is part of the problem, validate the progress owner with artifacts/scroll-reveal-surface-planning.md before tuning timing.

release-gate

Use when the implementation looks done and the remaining work is proof and cleanup.

• Start with artifacts/design-release-gate.md.
• Fill assets/templates/design-release-gate.v1.json.
• Re-run the real-surface matrix and the design review checklist.
• Follow the canonical direct-run release evidence policy from ../opendevbrowser-best-practices/SKILL.md; this pack does not redefine release-proof ownership.
• Fix remaining gaps before ship-audit.

Research-Backed Patterns

These patterns are summarized in artifacts/external-pattern-synthesis.md and should shape how the skill is applied:

• Specialized agents work best when scope, tooling, and examples are explicit.
• Frontend generation quality improves when prompts specify stack, layout intent, interaction states, and visual references instead of generic adjectives.
• Competitive harvest works best when each reference captures borrow and reject decisions instead of a mood board only.
• Large UI tasks should be broken into deliberate passes: contract, structure, implementation, then live validation.
• Real content and real workflows outperform placeholder-heavy prompts.
• Frontend design agents should own both aesthetics and verification, not just code output.
• Component libraries and screen families should be referenced intentionally instead of rediscovered from scratch on every task.
• Existing shipped surfaces should be treated as first-class adaptation inputs, not obstacles to work around.
• State ownership, overlay ownership, async ownership, and preview discipline need to be explicit or the implementation will drift even when the design language is strong.
• Route ownership should be explicit and typed: one owner translates deep links, tabs, URL params, and external entry points into screen state.
• Scroll-reveal work needs one declared progress owner and an explicit reduced-motion contract or it will regress across breakpoints.
• Debounced async search, layout-preserving placeholders, semantic token ownership, and non-reflow feedback surfaces should be decided in the contract instead of improvised during polish.
• Scan-heavy screens need stable item identity, lazy containers or progressive reveal where justified, and a declared scan unit before per-item polish or motion work.

Parallel Multitab Alignment

• Apply shared concurrency policy from ../opendevbrowser-best-practices/SKILL.md ("Parallel Operations").
• Treat design validation as session-per-worker; do not alternate unrelated target streams inside one session.
• Re-check extension readiness before /canvas or relay-backed annotation steps after idle windows.

Robustness Coverage (Known-Issue Matrix)

Matrix source: ../opendevbrowser-best-practices/artifacts/browser-agent-known-issues-matrix.md

• ISSUE-01: stale refs and DOM churn during iterative UI validation
• ISSUE-07: MV3 extension state loss during /canvas and popup-driven design loops
• ISSUE-08: restricted origins and unsupported extension pages during design validation
• ISSUE-12: stale evidence or unsupported design claims in final deliverables

Reload discipline for unpacked-extension design work:

• After npm run extension:build, do not trust a live Chrome result until the unpacked extension is actually reloaded in Chrome.
• Stale MV3 runtime state can preserve old popup or /canvas design-tab behavior even when the repo bundle is already fixed.
• If design-tab commands still throw restricted_url on chrome-extension://.../canvas.html, treat that as an unpacked-extension reload problem first, then reconnect the extension and rerun the design workflow.

Commands

./skills/opendevbrowser-design-agent/scripts/design-workflow.sh contract-first
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh canvas-contract
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh screenshot-audit
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh real-surface-validation
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh research-harvest
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh performance-audit
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh release-gate
./skills/opendevbrowser-design-agent/scripts/design-workflow.sh ship-audit
cat skills/opendevbrowser-design-agent/artifacts/design-agent-work-products.md
./skills/opendevbrowser-design-agent/scripts/extract-canvas-plan.sh .opendevbrowser/design-agent/<run-id>/design-contract.json > .tmp/canvas-plan.request.json

References

• Anthropic Claude Code subagents best practices: https://docs.anthropic.com/en/docs/claude-code/sub-agents
• Anthropic Claude Code settings and agent ownership patterns: https://docs.anthropic.com/en/docs/claude-code/settings
• Vercel v0 prompting guide: https://v0.dev/docs/prompting/text
• Lovable prompting guide: https://docs.lovable.dev/prompting/prompting-best-practices
• Public frontend-designer subagent example: https://github.com/iannuttall/claude-agents
• Dimillian SwiftUI UI patterns: https://github.com/Dimillian/Skills/blob/main/swiftui-ui-patterns/SKILL.md