---
id: S04
parent: M010
milestone: M010
provides:
  - GET /api/v1/search/suggestions endpoint
  - SearchAutocomplete shared component
requires:
  []
affects:
  []
key_files:
  - backend/schemas.py
  - backend/routers/search.py
  - backend/tests/test_search.py
  - frontend/src/components/SearchAutocomplete.tsx
  - frontend/src/api/public-client.ts
  - frontend/src/pages/Home.tsx
  - frontend/src/pages/SearchResults.tsx
  - frontend/src/App.css
key_decisions:
  - Used PostgreSQL unnest() for topic tag aggregation rather than canonical_tags.yaml
  - Popular suggestions fetched once on mount via ref guard, not re-fetched on every focus
  - Suggestion items use button elements since they trigger onSearch callback, not direct navigation
patterns_established:
  - Shared SearchAutocomplete component pattern: single component with props for hero sizing, initial query, and autofocus — reusable wherever search input is needed
observability_surfaces:
  - none
drill_down_paths:
  - .gsd/milestones/M010/slices/S04/tasks/T01-SUMMARY.md
  - .gsd/milestones/M010/slices/S04/tasks/T02-SUMMARY.md
duration: ""
verification_result: passed
completed_at: 2026-03-31T06:40:26.076Z
blocker_discovered: false
---

# S04: Search Autocomplete & Suggestions

**Added search autocomplete with popular suggestions on empty focus and debounced typeahead on 2+ chars, shared across Home and SearchResults pages.**

## What Happened

This slice added two things: a backend suggestions endpoint and a shared frontend autocomplete component.

**Backend (T01):** Added `GET /api/v1/search/suggestions` returning up to 12 popular items — top 4 technique pages by view_count, top 4 topic tags via PostgreSQL `unnest()` aggregation on the `topic_tags` array column, and top 4 creators (excluding hidden) by view_count. Each item has `text` and `type` (topic/technique/creator). Results are deduplicated case-insensitively with secondary sort by name for deterministic ordering when view counts tie. Five integration tests cover response shape, type coverage, deduplication, empty DB, and ordering.

**Frontend (T02):** Created `SearchAutocomplete.tsx` — a shared component encapsulating: (a) popular suggestions fetched once on mount from the new endpoint, shown on focus with empty input under a "Popular" header, (b) debounced typeahead search results on 2+ characters (existing pattern), (c) Escape/outside-click dismissal, (d) Enter submission via `onSearch` callback. The component replaced ~80 lines of inline typeahead logic in Home.tsx and a simpler search form in SearchResults.tsx. Both pages now use the same component with different props (`heroSize`, `initialQuery`, `autoFocus`).

API types (`SuggestionItem`, `SuggestionsResponse`) and `fetchSuggestions()` were added to `public-client.ts`. CSS for suggestion items with type badge color variants was added to App.css.

## Verification

Frontend build (`tsc -b && vite build`) passes with zero errors — 50 modules transformed, clean output. Backend suggestion tests (5 tests) require PostgreSQL on ub01; they passed during T01 execution via SSH tunnel (2.05s, all 5 green). Cannot re-run locally due to no local PostgreSQL — ConnectionRefusedError on 127.0.0.1:5433 is expected in this environment.

## Requirements Advanced

- R005 — Search UX enhanced with autocomplete suggestions — popular terms on empty focus and typeahead on 2+ chars on both Home and SearchResults pages
- R015 — Autocomplete reduces keystrokes needed to find techniques, supporting the 30-second retrieval target

## Requirements Validated

None.

## New Requirements Surfaced

None.

## Requirements Invalidated or Re-scoped

None.

## Deviations

Used PostgreSQL unnest() for topic tag aggregation instead of the canonical_tags.yaml pattern used by the topics router — more appropriate for suggestions since they reflect actual DB content rather than the full canonical tag list.

## Known Limitations

Backend suggestion tests require a live PostgreSQL database (ub01:5433 via SSH tunnel) — they cannot run in environments without database connectivity.

## Follow-ups

None.

## Files Created/Modified

- `backend/schemas.py` — Added SuggestionItem and SuggestionsResponse Pydantic schemas
- `backend/routers/search.py` — Added GET /suggestions endpoint with technique, topic, and creator aggregation queries
- `backend/tests/test_search.py` — Added 5 integration tests for the suggestions endpoint
- `frontend/src/api/public-client.ts` — Added SuggestionItem, SuggestionsResponse types and fetchSuggestions() function
- `frontend/src/components/SearchAutocomplete.tsx` — New shared autocomplete component with popular suggestions on focus and debounced typeahead
- `frontend/src/pages/Home.tsx` — Replaced ~80 lines of inline typeahead with SearchAutocomplete component
- `frontend/src/pages/SearchResults.tsx` — Replaced plain search form with SearchAutocomplete component
- `frontend/src/App.css` — Added CSS for suggestion items, popular header, and type badge color variants
