---
id: T02
parent: S01
milestone: M010
provides: []
requires: []
affects: []
key_files: ["frontend/src/pages/SubTopicPage.tsx", "frontend/src/api/public-client.ts", "frontend/src/App.tsx", "frontend/src/pages/TopicsBrowse.tsx", "frontend/src/App.css", "frontend/src/pages/Home.tsx"]
key_decisions: ["Grouped techniques by creator with Map-based first-appearance ordering", "Breadcrumb pattern: nav.breadcrumbs with link/text/current spans for reuse"]
patterns_established: []
drill_down_paths: []
observability_surfaces: []
duration: ""
verification_result: "TypeScript check (npx tsc --noEmit) passed with exit 0. Production build (npm run build) passed with exit 0, 48 modules transformed."
completed_at: 2026-03-31T06:03:01.860Z
blocker_discovered: false
---

# T02: Added SubTopicPage with breadcrumbs and creator-grouped technique list, wired /topics/:category/:subtopic route, updated TopicsBrowse links to dedicated pages

> Added SubTopicPage with breadcrumbs and creator-grouped technique list, wired /topics/:category/:subtopic route, updated TopicsBrowse links to dedicated pages

## What Happened
---
id: T02
parent: S01
milestone: M010
key_files:
  - frontend/src/pages/SubTopicPage.tsx
  - frontend/src/api/public-client.ts
  - frontend/src/App.tsx
  - frontend/src/pages/TopicsBrowse.tsx
  - frontend/src/App.css
  - frontend/src/pages/Home.tsx
key_decisions:
  - Grouped techniques by creator with Map-based first-appearance ordering
  - Breadcrumb pattern: nav.breadcrumbs with link/text/current spans for reuse
duration: ""
verification_result: passed
completed_at: 2026-03-31T06:03:01.860Z
blocker_discovered: false
---

# T02: Added SubTopicPage with breadcrumbs and creator-grouped technique list, wired /topics/:category/:subtopic route, updated TopicsBrowse links to dedicated pages

**Added SubTopicPage with breadcrumbs and creator-grouped technique list, wired /topics/:category/:subtopic route, updated TopicsBrowse links to dedicated pages**

## What Happened

Created SubTopicPage.tsx following CreatorDetail pattern: extracts category/subtopic from URL params, fetches via fetchSubTopicTechniques, groups by creator_name, renders breadcrumbs. Added API client function to public-client.ts. Registered route in App.tsx before /topics catch-all. Updated TopicsBrowse links from /search?q= to /topics/{cat}/{subtopic}. Added breadcrumb and sub-topic page CSS. Fixed pre-existing TS strict error in Home.tsx.

## Verification

TypeScript check (npx tsc --noEmit) passed with exit 0. Production build (npm run build) passed with exit 0, 48 modules transformed.

## Verification Evidence

| # | Command | Exit Code | Verdict | Duration |
|---|---------|-----------|---------|----------|
| 1 | `cd frontend && npx tsc --noEmit` | 0 | ✅ pass | 3400ms |
| 2 | `cd frontend && npm run build` | 0 | ✅ pass | 3300ms |


## Deviations

Fixed pre-existing TS strict error in Home.tsx (res.items[0] undefined narrowing) to pass npm run build.

## Known Issues

Slice-level pytest verification uses --timeout=30 but pytest-timeout not installed. Backend tests require PostgreSQL on ub01.

## Files Created/Modified

- `frontend/src/pages/SubTopicPage.tsx`
- `frontend/src/api/public-client.ts`
- `frontend/src/App.tsx`
- `frontend/src/pages/TopicsBrowse.tsx`
- `frontend/src/App.css`
- `frontend/src/pages/Home.tsx`


## Deviations
Fixed pre-existing TS strict error in Home.tsx (res.items[0] undefined narrowing) to pass npm run build.

## Known Issues
Slice-level pytest verification uses --timeout=30 but pytest-timeout not installed. Backend tests require PostgreSQL on ub01.
