diff --git a/src/core/content-analyzer.ts b/src/core/content-analyzer.ts
new file mode 100644
index 0000000..a497e87
--- /dev/null
+++ b/src/core/content-analyzer.ts
@@ -0,0 +1,171 @@
+import { CachedMetadata } from 'obsidian';
+import { ContentSnapshot, ContentDelta } from '../types';
+
+export class ContentAnalyzer {
+  private cache = new Map<string, ContentSnapshot>();
+
+  loadBaseline(baseline: Map<string, ContentSnapshot>): void {
+    this.cache = new Map(baseline);
+  }
+
+  getSnapshot(path: string): ContentSnapshot | undefined {
+    return this.cache.get(path);
+  }
+
+  removeSnapshot(path: string): void {
+    this.cache.delete(path);
+  }
+
+  renameSnapshot(oldPath: string, newPath: string): void {
+    const snap = this.cache.get(oldPath);
+    if (snap) {
+      this.cache.delete(oldPath);
+      snap.path = newPath;
+      this.cache.set(newPath, snap);
+    }
+  }
+
+  buildSnapshot(path: string, content: string, metadata: CachedMetadata | null): ContentSnapshot {
+    const snapshot: ContentSnapshot = {
+      path,
+      wordCount: countWords(content),
+      charCount: content.length,
+      links: extractLinks(metadata),
+      tags: extractTags(metadata),
+      headings: extractHeadings(metadata),
+      frontmatter: extractFrontmatter(metadata),
+      embeds: extractEmbeds(metadata),
+    };
+    this.cache.set(path, snapshot);
+    return snapshot;
+  }
+
+  analyze(path: string, content: string, metadata: CachedMetadata | null): ContentDelta | null {
+    const prev = this.cache.get(path);
+    const next = this.buildSnapshot(path, content, metadata);
+
+    if (!prev) return null;
+
+    const wordsAdded = Math.max(0, next.wordCount - prev.wordCount);
+    const wordsRemoved = Math.max(0, prev.wordCount - next.wordCount);
+
+    const linksAdded = diff(next.links, prev.links);
+    const linksRemoved = diff(prev.links, next.links);
+
+    const tagsAdded = diff(next.tags, prev.tags);
+    const tagsRemoved = diff(prev.tags, next.tags);
+
+    const headingsAdded = diffHeadings(next.headings, prev.headings);
+    const headingsRemoved = diffHeadings(prev.headings, next.headings);
+
+    const embedsAdded = diff(next.embeds, prev.embeds);
+    const embedsRemoved = diff(prev.embeds, next.embeds);
+
+    const { changed: frontmatterChanged, changes: frontmatterChanges } =
+      diffFrontmatter(prev.frontmatter, next.frontmatter);
+
+    return {
+      wordsAdded,
+      wordsRemoved,
+      linksAdded,
+      linksRemoved,
+      tagsAdded,
+      tagsRemoved,
+      headingsAdded,
+      headingsRemoved,
+      embedsAdded,
+      embedsRemoved,
+      frontmatterChanged,
+      frontmatterChanges,
+    };
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Extraction helpers
+// ---------------------------------------------------------------------------
+
+function countWords(content: string): number {
+  const stripped = content.replace(/^---[\s\S]*?---\n?/, '');
+  const words = stripped.split(/\s+/).filter(w => w.length > 0);
+  return words.length;
+}
+
+function extractLinks(meta: CachedMetadata | null): string[] {
+  if (!meta?.links) return [];
+  return meta.links.map(l => l.link);
+}
+
+function extractTags(meta: CachedMetadata | null): string[] {
+  const tags: string[] = [];
+  if (meta?.tags) {
+    for (const t of meta.tags) {
+      tags.push(t.tag);
+    }
+  }
+  if (meta?.frontmatter?.tags) {
+    const fmTags = meta.frontmatter.tags;
+    if (Array.isArray(fmTags)) {
+      for (const t of fmTags) {
+        const normalized = typeof t === 'string' && t.startsWith('#') ? t : `#${t}`;
+        if (!tags.includes(normalized)) tags.push(normalized);
+      }
+    }
+  }
+  return tags;
+}
+
+function extractHeadings(meta: CachedMetadata | null): { level: number; text: string }[] {
+  if (!meta?.headings) return [];
+  return meta.headings.map(h => ({ level: h.level, text: h.heading }));
+}
+
+function extractFrontmatter(meta: CachedMetadata | null): Record<string, unknown> {
+  if (!meta?.frontmatter) return {};
+  const fm: Record<string, unknown> = {};
+  for (const [key, value] of Object.entries(meta.frontmatter)) {
+    if (key === 'position') continue;
+    fm[key] = value;
+  }
+  return fm;
+}
+
+function extractEmbeds(meta: CachedMetadata | null): string[] {
+  if (!meta?.embeds) return [];
+  return meta.embeds.map(e => e.link);
+}
+
+// ---------------------------------------------------------------------------
+// Diff helpers
+// ---------------------------------------------------------------------------
+
+function diff(a: string[], b: string[]): string[] {
+  const bSet = new Set(b);
+  return a.filter(x => !bSet.has(x));
+}
+
+function diffHeadings(
+  a: { level: number; text: string }[],
+  b: { level: number; text: string }[],
+): { level: number; text: string }[] {
+  const bKeys = new Set(b.map(h => `${h.level}:${h.text}`));
+  return a.filter(h => !bKeys.has(`${h.level}:${h.text}`));
+}
+
+function diffFrontmatter(
+  prev: Record<string, unknown>,
+  next: Record<string, unknown>,
+): { changed: boolean; changes: Record<string, { old: unknown; new: unknown }> } {
+  const changes: Record<string, { old: unknown; new: unknown }> = {};
+
+  const allKeys = new Set([...Object.keys(prev), ...Object.keys(next)]);
+  for (const key of allKeys) {
+    const oldVal = prev[key];
+    const newVal = next[key];
+    if (JSON.stringify(oldVal) !== JSON.stringify(newVal)) {
+      changes[key] = { old: oldVal, new: newVal };
+    }
+  }
+
+  return { changed: Object.keys(changes).length > 0, changes };
+}
diff --git a/src/core/event-bus.ts b/src/core/event-bus.ts
new file mode 100644
index 0000000..595655f
--- /dev/null
+++ b/src/core/event-bus.ts
@@ -0,0 +1,100 @@
+import { LogfireEvent, EventType } from '../types';
+import { DatabaseManager } from './database';
+
+export class EventBus {
+  private buffer: LogfireEvent[] = [];
+  private subscribers = new Map<string, Set<(event: LogfireEvent) => void>>();
+  private flushTimer: ReturnType<typeof setInterval> | null = null;
+
+  constructor(
+    private db: DatabaseManager,
+    private flushIntervalMs: number,
+    private flushThreshold: number,
+  ) {
+    this.startFlushCycle();
+  }
+
+  // ---------------------------------------------------------------------------
+  // Emit & subscribe
+  // ---------------------------------------------------------------------------
+
+  emit(event: LogfireEvent): void {
+    this.buffer.push(event);
+    this.notifySubscribers(event);
+
+    if (this.buffer.length >= this.flushThreshold) {
+      this.flush();
+    }
+  }
+
+  onEvent(type: EventType | '*', callback: (event: LogfireEvent) => void): () => void {
+    if (!this.subscribers.has(type)) {
+      this.subscribers.set(type, new Set());
+    }
+    this.subscribers.get(type)!.add(callback);
+
+    return () => {
+      this.subscribers.get(type)?.delete(callback);
+    };
+  }
+
+  // ---------------------------------------------------------------------------
+  // Flush
+  // ---------------------------------------------------------------------------
+
+  flush(): void {
+    if (this.buffer.length === 0) return;
+
+    const batch = this.buffer.splice(0);
+    try {
+      this.db.insertEvents(batch);
+    } catch (err) {
+      console.error('[Logfire] Flush fehlgeschlagen:', err);
+      this.buffer.unshift(...batch);
+    }
+  }
+
+  getBufferSize(): number {
+    return this.buffer.length;
+  }
+
+  // ---------------------------------------------------------------------------
+  // Lifecycle
+  // ---------------------------------------------------------------------------
+
+  destroy(): void {
+    if (this.flushTimer !== null) {
+      clearInterval(this.flushTimer);
+      this.flushTimer = null;
+    }
+    this.flush();
+    this.subscribers.clear();
+  }
+
+  // ---------------------------------------------------------------------------
+  // Internals
+  // ---------------------------------------------------------------------------
+
+  private startFlushCycle(): void {
+    this.flushTimer = setInterval(() => this.flush(), this.flushIntervalMs);
+  }
+
+  private notifySubscribers(event: LogfireEvent): void {
+    this.notifySet(this.subscribers.get(event.type), event);
+    this.notifySet(this.subscribers.get('*'), event);
+  }
+
+  private notifySet(
+    subs: Set<(event: LogfireEvent) => void> | undefined,
+    event: LogfireEvent,
+  ): void {
+    if (!subs) return;
+    for (const cb of subs) {
+      try {
+        cb(event);
+      } catch (err) {
+        console.error('[Logfire] Subscriber-Fehler:', err);
+      }
+    }
+  }
+}
diff --git a/src/core/session-manager.ts b/src/core/session-manager.ts
new file mode 100644
index 0000000..1f78cd0
--- /dev/null
+++ b/src/core/session-manager.ts
@@ -0,0 +1,60 @@
+import { LogfireEvent, categoryForType } from '../types';
+import { EventBus } from './event-bus';
+import { DatabaseManager } from './database';
+
+export class SessionManager {
+  private _sessionId = '';
+  private _startTime = 0;
+
+  get currentSessionId(): string {
+    return this._sessionId;
+  }
+
+  get sessionDurationMs(): number {
+    if (this._startTime === 0) return 0;
+    return Date.now() - this._startTime;
+  }
+
+  constructor(
+    private eventBus: EventBus,
+    private db: DatabaseManager,
+    private vaultName: string,
+  ) {}
+
+  startSession(): void {
+    this._sessionId = crypto.randomUUID();
+    this._startTime = Date.now();
+
+    this.db.startSession(this._sessionId, this.vaultName);
+
+    this.eventBus.emit(this.createEvent('system:session-start', {
+      vaultName: this.vaultName,
+    }));
+  }
+
+  endSession(): void {
+    if (!this._sessionId) return;
+
+    this.eventBus.emit(this.createEvent('system:session-end', {
+      vaultName: this.vaultName,
+      duration: this.sessionDurationMs,
+    }));
+
+    this.db.endSession(this._sessionId);
+  }
+
+  private createEvent(
+    type: 'system:session-start' | 'system:session-end',
+    payload: Record<string, unknown>,
+  ): LogfireEvent {
+    return {
+      id: crypto.randomUUID(),
+      timestamp: Date.now(),
+      type,
+      category: categoryForType(type),
+      source: this.vaultName,
+      payload,
+      session: this._sessionId,
+    };
+  }
+}