# ADR 0003: Search via ILIKE instead of pg_trgm

- Status: accepted
- Date: 2026-09

## Context
Message search must find substring matches across a user's conversations.
pg_trgm + GIN gives indexed trigram search, but the extension is not
installed on the target system and cannot be created by a non-superuser role
(and adding it to the Docker image is an OS-level dependency).

## Decision
Search with `body ILIKE '%term%'` restricted to the user's conversations,
ordered by message id descending with a limit.

## Consequences
- No extension or superuser requirement; works on any PostgreSQL install.
- Sequential scan is instant for thousands of messages (family scale).
- Scaling path documented: `CREATE EXTENSION pg_trgm` + GIN index with
  `gin_trgm_ops`, keeping the same SQL semantics.