Projects — Scoped Workspaces
- Purpose: Isolated environments with their own chat history, knowledge base, and instructions
- Knowledge base limit: Up to 200K tokens of uploaded documents
- Permission levels: Can View (read-only) and Can Edit (full access)
- Chats: Private by default — not visible to other project members unless shared
- Cost: Built-in feature of Pro, Team, and Enterprise — no per-project fee
Project Instructions act as a persistent system prompt:
- Apply to every new chat in the project automatically
- Consume tokens from the context window (but not your message quota)
- Are not retroactive — existing open chats keep their original context
Anti-pattern: The "omni-project" — cramming marketing, legal, HR, and sales into one project causes context bleed. One workstream per project.
Context Files & Persistent Knowledge
The intern-to-colleague transformation: Context files turn Claude from a generic assistant into a configured colleague who already knows your industry, preferences, and standards.
Essential context files:
| File | Purpose |
|---|---|
| about-me.md | Your role, industry, priorities |
| brand-voice.md | 200-400 word writing sample + tone rules |
| working-preferences.md | Behavioural guardrails, banned phrases |
Writing sample calibration rules:
- 200-400 words of your actual writing (not descriptions of your tone)
- Show, do not tell — a concrete sample beats abstract adjectives
- Use tone contrasts: "Knowledgeable friend, not corporate press release"
Context window budget: Keep Project Instructions under 1,000 words. Front-load critical rules. Remove anything Claude can infer from a shorter instruction.
Memory System
| Feature | What It Does | Refresh Rate |
|---|---|---|
| Memory Synthesis | Automated summary of preferences and patterns | Every 24 hours |
| Chat Search | RAG retrieval across past conversations | Real-time query |
| Project Memory | Isolated per project, prevents cross-bleed | Per conversation |
| Manual Edit | Direct memory entry via pencil icon | Immediate |
| Incognito Chats | Ghost icon — not saved, not synthesised | N/A |
Critical distinctions:
- Memory synthesis is not real-time — 24-hour refresh cycle
- Chat Search searches conversations only — never files on your computer
- "Reset Memory" permanently deletes all synthesis data — no undo
- Enterprise can disable memory org-wide (permanent deletion for all users)
- Team members manage their own memory individually
Global Instructions & the Context Stack
The layered hierarchy:
| Layer | Scope | Use For |
|---|---|---|
| Profile Preferences | Every conversation, every project | Language, formatting basics, universal guardrails |
| Project Instructions | Within one project only | Role definitions, domain rules, knowledge references |
| Custom Styles | Formatting overlay | Sentence length, headers, detail level |
Rules that belong in Profile Preferences (global):
- "British English throughout"
- "No preambles or flattery — start with substance"
- "Always web-search before giving tech advice"
- "Instructions last updated: April 2026"
Rules that belong in Project Instructions (scoped):
- "Use our Agile-Hybrid methodology"
- "Reference the uploaded brand guide for tone"
- "Maximum 200 words per response"
Common trap: Global Preferences only apply to new chats — existing conversations keep their original context.
Model Selection Quick Guide
| Model | Best For | Rate Limit Impact |
|---|---|---|
| Haiku | Simple summaries, categorisation, batch extraction, quick lookups | Lightest |
| Sonnet | Daily work — writing, analysis, multi-step workflows (default choice) | Moderate |
| Opus | Deep research, complex reasoning, nuanced analysis, long documents | Heaviest |
Decision rules:
- If unsure → Sonnet (correct for 80-90% of professional tasks)
- If the task is mechanical and repetitive → Haiku
- If the task requires genuine deep reasoning → Opus
- Periodically retest — newer Sonnet may handle tasks that previously needed Opus
Adaptive Thinking: Modern model versions (4.6) automatically calibrate reasoning depth. No need to manually toggle extended thinking.
Common Exam Traps — Domain 5
| Trap | Correct Answer |
|---|---|
| "Project Instructions use up message limits" | They consume context window tokens but not message quota |
| "Chats in shared projects are visible to all members" | Chats are private by default unless manually shared |
| "Custom Styles and Project Instructions are the same" | Instructions control behaviour; Styles control formatting |
| "Global Preferences update existing conversations" | They only apply to new chats started after saving |
| "Memory synthesis updates in real time" | 24-hour refresh cycle, not real-time |
| "Reset Memory can be undone within 30 days" | Permanent deletion with no recovery |
| "Writing samples are only for creative projects" | Critical for professional email, report, and client communication consistency |
| "Always use Opus for best quality" | Wastes rate limits on tasks Sonnet handles equally well |
| "Each model version is a minor patch" | Each version is a separate training run with different strengths |