diff --git a/src/becca/entities/abstract_becca_entity.ts b/src/becca/entities/abstract_becca_entity.ts
index 50e76a212..1505a8830 100644
--- a/src/becca/entities/abstract_becca_entity.ts
+++ b/src/becca/entities/abstract_becca_entity.ts
@@ -273,7 +273,7 @@ abstract class AbstractBeccaEntity<T extends AbstractBeccaEntity<T>> {
      *
      * This is a low-level method, for notes and branches use `note.deleteNote()` and 'branch.deleteBranch()` instead.
      */
-    markAsDeleted(deleteId = null) {
+    markAsDeleted(deleteId: string | null = null) {
         const constructorData = (this.constructor as unknown as ConstructorData<T>);
         const entityId = (this as any)[constructorData.primaryKeyName];
         const entityName = constructorData.entityName;
diff --git a/src/becca/entities/battachment.ts b/src/becca/entities/battachment.ts
index 728ee5e14..d2d0b8498 100644
--- a/src/becca/entities/battachment.ts
+++ b/src/becca/entities/battachment.ts
@@ -36,7 +36,7 @@ class BAttachment extends AbstractBeccaEntity<BAttachment> {
     noteId?: number;
     attachmentId?: string;
     /** either noteId or revisionId to which this attachment belongs */
-    ownerId: string;
+    ownerId?: string;
     role: string;
     mime: string;
     title: string;
diff --git a/src/becca/entities/battribute.ts b/src/becca/entities/battribute.ts
index 5afea9fdb..15e6ea911 100644
--- a/src/becca/entities/battribute.ts
+++ b/src/becca/entities/battribute.ts
@@ -7,6 +7,10 @@ import promotedAttributeDefinitionParser = require('../../services/promoted_attr
 import sanitizeAttributeName = require('../../services/sanitize_attribute_name');
 import { AttributeRow, AttributeType } from './rows.js';
 
+interface SavingOpts {
+    skipValidation?: boolean;
+}
+
 /**
  * Attribute is an abstract concept which has two real uses - label (key - value pair)
  * and relation (representing named relationship between source and target note)
@@ -174,7 +178,7 @@ class BAttribute extends AbstractBeccaEntity<BAttribute> {
         return !(this.attributeId in this.becca.attributes);
     }
 
-    beforeSaving(opts = {}) {
+    beforeSaving(opts: SavingOpts = {}) {
         if (!opts.skipValidation) {
             this.validate();
         }
diff --git a/src/becca/entities/bbranch.ts b/src/becca/entities/bbranch.ts
index 8892166c4..6c767197e 100644
--- a/src/becca/entities/bbranch.ts
+++ b/src/becca/entities/bbranch.ts
@@ -83,18 +83,18 @@ class BBranch extends AbstractBeccaEntity<BBranch> {
         }
 
         const parentNote = this.parentNote;
-
-        if (!childNote.parents.includes(parentNote)) {
-            childNote.parents.push(parentNote);
-        }
-
-        if (!parentNote.children.includes(childNote)) {
-            parentNote.children.push(childNote);
+        if (parentNote) {
+            if (!childNote.parents.includes(parentNote)) {
+                childNote.parents.push(parentNote);
+            }
+    
+            if (!parentNote.children.includes(childNote)) {
+                parentNote.children.push(childNote);
+            }
         }
     }
 
-    /** @returns {BNote} */
-    get childNote() {
+    get childNote(): BNote {
         if (!(this.noteId in this.becca.notes)) {
             // entities can come out of order in sync/import, create skeleton which will be filled later
             this.becca.addNote(this.noteId, new BNote({noteId: this.noteId}));
@@ -103,13 +103,12 @@ class BBranch extends AbstractBeccaEntity<BBranch> {
         return this.becca.notes[this.noteId];
     }
 
-    /** @returns {BNote} */
-    getNote() {
+    getNote(): BNote {
         return this.childNote;
     }
 
-    /** @returns {BNote|undefined} - root branch will have undefined parent, all other branches have to have a parent note */
-    get parentNote() {
+    /** @returns root branch will have undefined parent, all other branches have to have a parent note */
+    get parentNote(): BNote | undefined {
         if (!(this.parentNoteId in this.becca.notes) && this.parentNoteId !== 'none') {
             // entities can come out of order in sync/import, create skeleton which will be filled later
             this.becca.addNote(this.parentNoteId, new BNote({noteId: this.parentNoteId}));
@@ -119,7 +118,7 @@ class BBranch extends AbstractBeccaEntity<BBranch> {
     }
 
     get isDeleted() {
-        return !(this.branchId in this.becca.branches);
+        return (this.branchId == undefined || !(this.branchId in this.becca.branches));
     }
 
     /**
diff --git a/src/becca/entities/bnote.ts b/src/becca/entities/bnote.ts
index 6c7ed6895..232df43f4 100644
--- a/src/becca/entities/bnote.ts
+++ b/src/becca/entities/bnote.ts
@@ -64,15 +64,16 @@ class BNote extends AbstractBeccaEntity<BNote> {
     isBeingDeleted!: boolean;
     isDecrypted!: boolean;
     
+    ownedAttributes!: BAttribute[];
+    parentBranches!: BBranch[];
+    parents!: BNote[];
+    children!: BNote[];
+    targetRelations!: BAttribute[];
+
     private __flatTextCache!: string | null;
 
-    private parentBranches!: BBranch[];
-    private parents!: BNote[];
-    private children!: BNote[];
-    private ownedAttributes!: BAttribute[];
     private __attributeCache!: BAttribute[] | null;
     private __inheritableAttributeCache!: BAttribute[] | null;
-    private targetRelations!: BAttribute[];
     private __ancestorCache!: BNote[] | null;
 
     // following attributes are filled during searching in the database
@@ -85,7 +86,7 @@ class BNote extends AbstractBeccaEntity<BNote> {
     /** number of note revisions for this note */
     private revisionCount!: number | null;
 
-    constructor(row: NoteRow) {
+    constructor(row: Partial<NoteRow>) {
         super();
 
         if (!row) {
@@ -96,7 +97,7 @@ class BNote extends AbstractBeccaEntity<BNote> {
         this.init();
     }
 
-    updateFromRow(row: NoteRow) {
+    updateFromRow(row: Partial<NoteRow>) {
         this.update([
             row.noteId,
             row.title,
@@ -215,17 +216,15 @@ class BNote extends AbstractBeccaEntity<BNote> {
      * - changes in the note metadata or title should not trigger note content sync (so we keep separate utcDateModified and entity changes records)
      * - but to the user note content and title changes are one and the same - single dateModified (so all changes must go through Note and content is not a separate entity)
      */
-
-    /** @returns {string|Buffer}  */
-    getContent() {
-        return this._getContent();
+    // FIXME: original declaration was (string | Buffer), but everywhere it's used as a string.
+    getContent(): string {
+        return this._getContent() as string;
     }
 
     /**
-     * @returns {*}
      * @throws Error in case of invalid JSON */
-    getJsonContent() {
-        const content = this.getContent() as string;
+    getJsonContent(): {} | null {
+        const content = this.getContent();
 
         if (!content || !content.trim()) {
             return null;
@@ -1496,7 +1495,7 @@ class BNote extends AbstractBeccaEntity<BNote> {
             return null;
         }
 
-        const content = this.getContent() as string;
+        const content = this.getContent();
 
         const parentNote = this.getParentNotes()[0];
         const attachment = parentNote.saveAttachment({
@@ -1506,7 +1505,7 @@ class BNote extends AbstractBeccaEntity<BNote> {
             content: content
         });
 
-        let parentContent = parentNote.getContent() as string;
+        let parentContent = parentNote.getContent();
 
         const oldNoteUrl = `api/images/${this.noteId}/`;
         const newAttachmentUrl = `api/attachments/${attachment.attachmentId}/image/`;
@@ -1584,7 +1583,7 @@ class BNote extends AbstractBeccaEntity<BNote> {
      */
     saveRevision() {
         return sql.transactional(() => {
-            let noteContent = this.getContent() as string;
+            let noteContent = this.getContent();
 
             const revision = new BRevision({
                 noteId: this.noteId,
diff --git a/src/becca/entities/boption.ts b/src/becca/entities/boption.ts
index 871e44157..c72a41c11 100644
--- a/src/becca/entities/boption.ts
+++ b/src/becca/entities/boption.ts
@@ -7,7 +7,7 @@ import { OptionRow } from './rows';
 /**
  * Option represents a name-value pair, either directly configurable by the user or some system property.
  */
-class BOption extends AbstractBeccaEntity {
+class BOption extends AbstractBeccaEntity<BOption> {
     static get entityName() { return "options"; }
     static get primaryKeyName() { return "name"; }
     static get hashedProperties() { return ["name", "value"]; }
diff --git a/src/becca/entities/brecent_note.ts b/src/becca/entities/brecent_note.ts
index a6796d0ff..8dbaf533c 100644
--- a/src/becca/entities/brecent_note.ts
+++ b/src/becca/entities/brecent_note.ts
@@ -7,10 +7,8 @@ import AbstractBeccaEntity = require('./abstract_becca_entity.js');
 
 /**
  * RecentNote represents recently visited note.
- *
- * @extends AbstractBeccaEntity
  */
-class BRecentNote extends AbstractBeccaEntity {
+class BRecentNote extends AbstractBeccaEntity<BRecentNote> {
     static get entityName() { return "recent_notes"; }
     static get primaryKeyName() { return "noteId"; }
 
diff --git a/src/becca/entities/brevision.ts b/src/becca/entities/brevision.ts
index 90250b876..cabbf5757 100644
--- a/src/becca/entities/brevision.ts
+++ b/src/becca/entities/brevision.ts
@@ -28,18 +28,19 @@ class BRevision extends AbstractBeccaEntity<BRevision> {
     static get hashedProperties() { return ["revisionId", "noteId", "title", "isProtected", "dateLastEdited", "dateCreated",
                                             "utcDateLastEdited", "utcDateCreated", "utcDateModified", "blobId"]; }
 
-    revisionId: string;
+    revisionId?: string;
     noteId: string;
     type: string;
     mime: string;
     isProtected: boolean;
     title: string;
-    blobId: string;
-    dateLastEdited: string;
+    blobId?: string;
+    dateLastEdited?: string;
     dateCreated: string;
-    utcDateLastEdited: string;
+    utcDateLastEdited?: string;
     utcDateCreated: string;
     contentLength?: number;
+    content?: string;
 
     constructor(row: RevisionRow, titleDecrypted = false) {
         super();
@@ -68,8 +69,8 @@ class BRevision extends AbstractBeccaEntity<BRevision> {
         return becca.notes[this.noteId];
     }
 
-    /** @returns {boolean} true if the note has string content (not binary) */
-    hasStringContent() {
+    /** @returns true if the note has string content (not binary) */
+    hasStringContent(): boolean {
         return utils.isStringNote(this.type, this.mime);
     }
 
@@ -87,8 +88,9 @@ class BRevision extends AbstractBeccaEntity<BRevision> {
      *
      * This is the same approach as is used for Note's content.
      */
-    getContent(): string | Buffer {
-        return this._getContent();
+    // FIXME: initial declaration included Buffer, but everywhere it's treated as a string.
+    getContent(): string {
+        return this._getContent() as string;
     }
 
     /**
diff --git a/src/services/options.ts b/src/services/options.ts
index 41532d74f..a7b5ad475 100644
--- a/src/services/options.ts
+++ b/src/services/options.ts
@@ -93,7 +93,7 @@ function getOptionMap() {
     return map;
 }
 
-module.exports = {
+export = {
     getOption,
     getOptionInt,
     getOptionBool,