---
id: T02
parent: S05
milestone: M006
provides: []
requires: []
affects: []
key_files: ["frontend/src/pages/TopicsBrowse.tsx", "frontend/src/App.css"]
key_decisions: ["Used 3px colored left border + small colored dot for category visual differentiation — subtler than full colored header, maintains dark theme cohesion", "Computed totalTechniques client-side via sub_topics.reduce() — no API changes needed"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "Frontend build passes (800ms, no errors). Live CSS and JS bundles contain topic-card class references. API returns 7 categories. Browser verification confirms 2-column desktop grid, 1-column mobile, filter narrows to matching cards, expand/collapse toggles work correctly."
completed_at: 2026-03-30T11:48:43.282Z
blocker_discovered: false
---

# T02: Rewrote TopicsBrowse.tsx from vertical accordion to responsive 2-column card grid with category color accents, summary stats, and expand/collapse toggles

> Rewrote TopicsBrowse.tsx from vertical accordion to responsive 2-column card grid with category color accents, summary stats, and expand/collapse toggles

## What Happened
---
id: T02
parent: S05
milestone: M006
key_files:
  - frontend/src/pages/TopicsBrowse.tsx
  - frontend/src/App.css
key_decisions:
  - Used 3px colored left border + small colored dot for category visual differentiation — subtler than full colored header, maintains dark theme cohesion
  - Computed totalTechniques client-side via sub_topics.reduce() — no API changes needed
duration: ""
verification_result: passed
completed_at: 2026-03-30T11:48:43.283Z
blocker_discovered: false
---

# T02: Rewrote TopicsBrowse.tsx from vertical accordion to responsive 2-column card grid with category color accents, summary stats, and expand/collapse toggles

**Rewrote TopicsBrowse.tsx from vertical accordion to responsive 2-column card grid with category color accents, summary stats, and expand/collapse toggles**

## What Happened

Replaced the single-column accordion layout with a CSS grid card layout. Each card shows a colored left border and dot (via existing badge custom properties), category name, description, sub-topic + technique count stats line, and expand/collapse toggle. Grid is 2 columns on desktop, 1 on mobile. CSS rewritten from .topics-list/.topic-category* to .topics-grid/.topic-card* classes. All existing functionality preserved (filter, expand/collapse, sub-topic navigation). Deployed to ub01 and verified in browser at both desktop and mobile viewports.

## Verification

Frontend build passes (800ms, no errors). Live CSS and JS bundles contain topic-card class references. API returns 7 categories. Browser verification confirms 2-column desktop grid, 1-column mobile, filter narrows to matching cards, expand/collapse toggles work correctly.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd frontend && npm run build` | 0 | ✅ pass | 800ms |
| 2 | `curl CSS bundle | grep topic-card` | 0 | ✅ pass | 200ms |
| 3 | `curl JS bundle | grep topic-card` | 0 | ✅ pass | 200ms |
| 4 | `curl API /topics | assert len==7` | 0 | ✅ pass | 300ms |
| 5 | `Browser: desktop 2-col grid + mobile 1-col + filter + toggle` | 0 | ✅ pass | 5000ms |


## Deviations

Plan verification command used grep on HTML for topic-category classes, but SPA serves class names in JS bundles — adapted to check bundle contents instead.

## Known Issues

None.

## Files Created/Modified

- `frontend/src/pages/TopicsBrowse.tsx`
- `frontend/src/App.css`


## Deviations
Plan verification command used grep on HTML for topic-category classes, but SPA serves class names in JS bundles — adapted to check bundle contents instead.

## Known Issues
None.
