Establish initial project architecture

docs/architecture.md

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+# Architecture
+
+## Purpose
+
+The Meeting Knowledge Assistant transforms recorded meetings into structured organizational knowledge through a modular processing pipeline.
+
+---
+
+# Design Principles
+
+- Architecture first
+- Offline first where practical
+- Immutable source data
+- Replaceable AI components
+- Small, focused modules
+- Explicit interfaces
+- Reproducible AI outputs
+
+---
+
+# High-Level Pipeline
+
+Recording
+    ↓
+Transcription
+    ↓
+Speaker Diarization
+    ↓
+Working Transcript
+    ↓
+LLM Analysis
+    ↓
+Knowledge Extraction
+    ↓
+Export
+
+---
+
+# Domain Model
+
+Meeting
+│
+├── Recording
+├── Transcript
+│     ├── Canonical
+│     └── Working
+├── Speakers
+├── Participants
+├── AI Artifacts
+├── Knowledge Objects
+├── Attachments
+└── Exports
+
+---
+
+# Module Responsibilities
+
+## Recorder
+
+Responsible only for capturing audio.
+
+Input:
+None
+
+Output:
+Recording
+
+---
+
+## Transcription
+
+Responsible only for speech-to-text conversion.
+
+Input:
+Recording
+
+Output:
+Canonical Transcript
+
+---
+
+## Diarization
+
+Responsible only for speaker identification.
+
+Input:
+Recording + Canonical Transcript
+
+Output:
+Working Transcript
+
+---
+
+## LLM
+
+Responsible for semantic analysis.
+
+Input:
+Transcript
+
+Output:
+AI Artifacts
+
+---
+
+## Knowledge Extraction
+
+Responsible for creating structured knowledge.
+
+Input:
+AI Artifacts
+
+Output:
+Knowledge Objects
+
+---
+
+## Export
+
+Responsible for creating user-facing documents.
+
+Input:
+Knowledge Objects
+
+Output:
+Markdown
+PDF
+DOCX
+
+---
+
+# Artifact Lifecycle
+
+Recording
+
+↓
+
+Canonical Transcript
+
+↓
+
+Working Transcript
+
+↓
+
+AI Artifacts
+
+↓
+
+Knowledge Objects
+
+↓
+
+Exports
+
+---
+
+# Storage Strategy
+
+The domain model is independent of the storage backend.
+
+Possible implementations:
+
+- File System
+- SQLite
+- PostgreSQL
+- Cloud Storage
+
+---
+
+# Future Extensions
+
+- Live transcription
+- Video processing
+- OCR
+- Semantic search
+- Knowledge graph
+- Company glossary
+- Multi-language meetings
+- Local LLM support