docs: add fuzzy search and relevance ordering documentation

docs/orm/api/filter.md

@@ -19,6 +19,7 @@ You can filter on scalar fields with values or operators as supported by the fie
 - `in` `notIn`: all scalar fields
 - `contains` `startsWith` `endsWith`: `String` fields
 - `lt` `lte` `gt` `gte` `between`: `String`, `Int`, `BigInt`, `Float`, `Decimal`, and `Date` fields
+- `fuzzy` `fuzzyContains`: `String` fields (PostgreSQL only, see [Fuzzy search filters](#fuzzy-search-filters))
 
 A filter object can contain multiple field filters, and they are combined with `AND` semantic. You can also use the `AND`, `OR`, and `NOT` logical operators to combine filter objects to form a complex filter.
 
@@ -118,6 +119,125 @@ Filters can be defined on conditions over relations. For one-to-one relations, y
 
 <StackBlitzGithub repoPath="zenstackhq/v3-doc-orm" openFile="filter/relation.ts" startScript="generate,filter:relation" />
 
+## Fuzzy search filters
+
+:::info
+Fuzzy search is only supported by the **PostgreSQL** provider and requires the `pg_trgm` and `unaccent` extensions to be enabled.
+:::
+
+ZenStack provides built-in fuzzy search operators for `String` fields, powered by PostgreSQL's trigram similarity. This allows you to find records with approximate string matching - useful for handling typos, accent-insensitive searches, and substring matching.
+
+### Prerequisites
+
+Enable the required PostgreSQL extensions:
+
+```sql
+CREATE EXTENSION IF NOT EXISTS unaccent;
+CREATE EXTENSION IF NOT EXISTS pg_trgm;
+```
+
+### `fuzzy` - Trigram similarity
+
+The `fuzzy` operator matches strings that are similar to the search term, using the `%` trigram similarity operator with `unaccent` for accent-insensitive matching.
+
+```ts
+// Find products with names similar to "creme" (matches "Crème brûlée", "Crème fraîche")
+await db.product.findMany({
+  where: { name: { fuzzy: 'creme' } }
+});
+
+// Handles typos: "Aple" matches "Apple"
+await db.product.findMany({
+  where: { name: { fuzzy: 'Aple' } }
+});
+```
+
+### `fuzzyContains` - Fuzzy substring matching
+
+The `fuzzyContains` operator checks if the search term is approximately contained within the field value, using the `<%` word similarity operator.
+
+```ts
+// Find products where "choco" is approximately contained in the name
+// Matches "Éclair au chocolat"
+await db.product.findMany({
+  where: { name: { fuzzyContains: 'choco' } }
+});
+```
+
+### Combining fuzzy with other filters
+
+Fuzzy operators can be combined with other filter operators on the same field or across fields:
+
+```ts
+// Fuzzy + contains on the same field
+await db.product.findMany({
+  where: { name: { fuzzy: 'creme', contains: 'brûlée' } }
+});
+
+// Fuzzy on one field + standard filter on another
+await db.product.findMany({
+  where: {
+    name: { fuzzy: 'creme' },
+    description: { contains: 'custard' }
+  }
+});
+```
+
+### Sorting by relevance
+
+Use `_relevance` in `orderBy` to sort results by how closely they match a search term, using PostgreSQL's `similarity()` function:
+
+```ts
+await db.product.findMany({
+  where: { name: { fuzzy: 'creme' } },
+  orderBy: {
+    _relevance: {
+      fields: ['name'],
+      search: 'creme',
+      sort: 'desc'
+    }
+  }
+});
+
+// Relevance across multiple fields
+await db.product.findMany({
+  where: {
+    OR: [
+      { name: { fuzzy: 'chocolate' } },
+      { description: { fuzzy: 'chocolate' } },
+    ]
+  },
+  orderBy: {
+    _relevance: {
+      fields: ['name', 'description'],
+      search: 'chocolate',
+      sort: 'desc'
+    }
+  }
+});
+```
+
+:::caution
+`_relevance` ordering cannot be combined with cursor-based pagination.
+:::
+
+### Fuzzy filters in mutations
+
+Fuzzy operators work in all operations that accept `where` clauses, including `updateMany`, `deleteMany`, `count`, and `groupBy`:
+
+```ts
+// Update all records matching the fuzzy search
+await db.product.updateMany({
+  where: { name: { fuzzy: 'creme' } },
+  data: { category: 'French desserts' }
+});
+
+// Count fuzzy matches
+const count = await db.product.count({
+  where: { description: { fuzzyContains: 'pastry' } }
+});
+```
+
 ## Query builder filters
 
 <ZenStackVsPrisma>

docs/orm/api/find.md

@@ -51,6 +51,8 @@ Use the `orderBy` field to control the sort field, direction, and null field pla
 
 <StackBlitzGithub repoPath="zenstackhq/v3-doc-orm" openFile="find/sort.ts" startScript="generate,find:sort" />
 
+You can also sort by fuzzy search relevance using `_relevance`. See [Fuzzy search filters](./filter.md#sorting-by-relevance) for details.
+
 ## Pagination
 
 You can use two strategies for pagination: offset-based or cursor-based. Pagination is not supported for `findUnique` and `findUniqueOrThrow`.