feat(coderd): add q search parameter to chats endpoint (#22913)

Replace the standalone `?archived=` query parameter on the chats listing
endpoint with a `?q=` search parameter, consistent with how workspaces,
tasks, templates, and other list endpoints work.

The `q` parameter uses the standard `key:value` search syntax parsed by
the `searchquery` package. Currently supports:

- `archived:true/false` (default: `false`, hides archived chats)

When `q` is empty or omits the archived filter, archived chats are
excluded by default. This is a behavioral change — the previous API
returned all chats (including archived) when no filter was specified.

### Changes

**Backend:**
- Add `searchquery.Chats()` parser following the same pattern as
`Tasks()`, `Workspaces()`, etc.
- Update `listChats` handler to read `q` instead of `archived`
- Update `codersdk.ListChatsOptions` to use `Q string` instead of
`Archived *bool`

**Frontend:**
- Update `getChats` API method to accept `q` parameter
- Update `infiniteChats` query to pass `q` instead of `archived`

**Tests:**
- Add `TestSearchChats` unit tests for the parser
- Update existing archive/unarchive integration tests to use `Q:
"archived:true"` syntax

coderd/searchquery/search.go

@@ -467,6 +467,36 @@ func Tasks(ctx context.Context, db database.Store, query string, actorID uuid.UU
 	return filter, parser.Errors
 }
 
+// Chats parses a search query for chats.
+//
+// Supported query parameters:
+//   - archived: boolean (default: false, excludes archived chats unless explicitly set)
+func Chats(query string) (database.GetChatsByOwnerIDParams, []codersdk.ValidationError) {
+	filter := database.GetChatsByOwnerIDParams{
+		// Default to hiding archived chats.
+		Archived: sql.NullBool{Bool: false, Valid: true},
+	}
+
+	if query == "" {
+		return filter, nil
+	}
+
+	// Always lowercase for all searches.
+	query = strings.ToLower(query)
+	values, errors := searchTerms(query, func(term string, _ url.Values) error {
+		return xerrors.Errorf("unsupported search term: %q", term)
+	})
+	if len(errors) > 0 {
+		return filter, errors
+	}
+
+	parser := httpapi.NewQueryParamParser()
+	filter.Archived = parser.NullableBoolean(values, filter.Archived, "archived")
+
+	parser.ErrorExcessParams(values)
+	return filter, parser.Errors
+}
+
 func searchTerms(query string, defaultKey func(term string, values url.Values) error) (url.Values, []codersdk.ValidationError) {
 	searchValues := make(url.Values)
 

coderd/searchquery/search_test.go

@@ -1215,3 +1215,75 @@ func TestSearchTasks(t *testing.T) {
 		})
 	}
 }
+
+func TestSearchChats(t *testing.T) {
+	t.Parallel()
+
+	testCases := []struct {
+		Name                  string
+		Query                 string
+		Expected              database.GetChatsByOwnerIDParams
+		ExpectedErrorContains string
+	}{
+		{
+			Name:  "Empty",
+			Query: "",
+			Expected: database.GetChatsByOwnerIDParams{
+				Archived: sql.NullBool{Bool: false, Valid: true},
+			},
+		},
+		{
+			Name:  "ArchivedTrue",
+			Query: "archived:true",
+			Expected: database.GetChatsByOwnerIDParams{
+				Archived: sql.NullBool{Bool: true, Valid: true},
+			},
+		},
+		{
+			Name:  "ArchivedFalse",
+			Query: "archived:false",
+			Expected: database.GetChatsByOwnerIDParams{
+				Archived: sql.NullBool{Bool: false, Valid: true},
+			},
+		},
+		{
+			Name:                  "ExtraParam",
+			Query:                 "archived:true invalid:param",
+			ExpectedErrorContains: "is not a valid query param",
+		},
+		{
+			Name:                  "ExtraColon",
+			Query:                 "archived:true:extra",
+			ExpectedErrorContains: "can only contain 1 ':'",
+		},
+		{
+			Name:                  "PrefixColon",
+			Query:                 ":archived",
+			ExpectedErrorContains: "cannot start or end with ':'",
+		},
+		{
+			Name:                  "SuffixColon",
+			Query:                 "archived:",
+			ExpectedErrorContains: "cannot start or end with ':'",
+		},
+	}
+
+	for _, c := range testCases {
+		t.Run(c.Name, func(t *testing.T) {
+			t.Parallel()
+
+			values, errs := searchquery.Chats(c.Query)
+			if c.ExpectedErrorContains != "" {
+				require.True(t, len(errs) > 0, "expect some errors")
+				var s strings.Builder
+				for _, err := range errs {
+					_, _ = s.WriteString(fmt.Sprintf("%s: %s\n", err.Field, err.Detail))
+				}
+				require.Contains(t, s.String(), c.ExpectedErrorContains)
+			} else {
+				require.Len(t, errs, 0, "expected no error")
+				require.Equal(t, c.Expected, values, "expected values")
+			}
+		})
+	}
+}