---
slug: claude-virtual-filesystem-guide
title: "Inside Claude's Sandbox: What Happens When Claude Creates a File"
author: henry
status: ready
created: 2024-12-25
updated: 2026-01-07
revised: 2026-01-07
content_type: tutorial

primary_keyword: "claude file creation"
secondary_keywords: ["claude sandbox", "claude sandbox environment", "claude mcp filesystem", "where does claude save files"]

meta_description: "Learn where Claude saves files in its sandbox filesystem. Discover the /mnt/user-data/ structure, fix missing file issues, and master file workflows with this hands-on guide."

assets_folder: assets/claude-virtual-filesystem-guide/
images: pending
---

# Brief

## Strategic Context

### Why This Article?
No one has documented Claude's internal sandbox filesystem structure in claude.ai. Users encounter frustration when files "disappear" or Claude creates files in the wrong location. This is Henry's first article — establishes technical credibility with an original investigation that provides real value.

**Availability:** Code execution and file creation requires **paid plans** (Pro, Max, Team, Enterprise). Free plan only has Artifacts.

### Target Reader
- **Role:** AI-first developer using Claude Pro/Max with "Code execution and file creation" enabled
- **Situation:** Using Claude for code generation, file creation, possibly with Filesystem MCP in Claude Desktop
- **Pain:** Files created by Claude don't appear where expected; confusion between internal sandbox and Filesystem MCP
- **Search query:** "claude file creation not working", "where does claude save files", "claude mcp vs sandbox"

### Terminology Clarification (for article)
| Term | What it means |
|------|---------------|
| "Code execution and file creation" | Official Anthropic name for sandbox feature in claude.ai |
| Sandbox / Sandboxed environment | Ubuntu container where Claude runs code |
| Artifacts | Interactive previews (HTML, React, SVG) — separate feature from file creation |
| Filesystem MCP | External MCP server for local file access (Claude Desktop only) |
| "Virtual filesystem" | NOT official term, but Claude understands it in conversation — tested in practice |

### Success Metrics
- Primary: Organic traffic from developers searching for Claude file issues
- Secondary: Social shares from AI dev communities (Reddit, Twitter, Dev.to)

---

## SEO Strategy

### Keywords
| Type | Keyword | Notes |
|------|---------|-------|
| Primary | claude file creation | High intent, problem-focused |
| Secondary | claude sandbox environment | Technical term users encounter |
| Secondary | claude mcp filesystem | Confusion point we address |
| Secondary | claude virtual filesystem | Descriptive, long-tail |

### Search Intent
User expects: practical explanation of where Claude stores files, how to find them, how to control file location.

### Competition
- Anthropic docs exist but are high-level, don't show internal paths
- No articles specifically about `/mnt/user-data/` structure
- Our angle: hands-on investigation with screenshots and "try it yourself" exercises

### Unique Angle
First-hand debugging story with reproducible experiments. Reader can follow along and discover the filesystem themselves.

---

## Content Requirements

### Core Question
**Where do files go when Claude creates them, and how do I make Claude save files where I actually want them?**

### Must Cover
1. Sandbox filesystem structure overview (key folders and their purposes)
2. What happens when Claude creates a file (step by step)
3. The `/mnt/user-data/outputs/` → sidebar connection
4. Problem: Claude confusing internal sandbox vs Filesystem MCP (in Claude Desktop)
5. Solution: how to direct Claude to the right tool
6. **Two strategies for file workflows** (see below)
7. "Try it yourself" experiments for readers
8. Quick note: this requires paid plan (Pro+)

### Two File Workflow Strategies (new section)

**Strategy 1: Work in sandbox, save at end**
- Work with files inside `/home/claude/` during conversation
- Only move to `/mnt/user-data/outputs/` when done
- Pros: Faster iteration, no filesystem noise, sandbox is temp anyway
- Cons: Lose work if you forget to save, files not visible until end

**Strategy 2: Save to local disk immediately (via Filesystem MCP)**
- Claude saves directly to local filesystem via MCP
- Pros: Files persist immediately, work directly with your project files
- Cons: Requires MCP setup in Claude Desktop, can't use in claude.ai web

### Must NOT Cover
- MCP server installation guide (separate topic, just mention it exists)
- API code execution tool (different product)
- Artifacts deep dive (mention briefly for context on naming confusion)

### Note on Artifacts vs Files (sidebar box)
Users often confuse "artifacts" and "files":
- **Artifacts** (June 2024): Interactive previews that render in sidebar — HTML, React, SVG, code snippets
- **Files** (September 2025): Actual downloadable documents — .docx, .xlsx, .pdf, created via sandbox

Artifacts had a highlight+edit feature (September 2024) where you could select code and click "Improve" or "Explain". This may have changed after the October 2025 UI update when Code Execution became default. The current interface separates Artifacts from file creation more clearly.

### Unique Angle
Personal debugging story: "I spent hours confused about where my files went. Here's what I discovered."

### Banatie Integration
- Type: none
- Rationale: First Henry article, establish credibility first. No forced mentions.

---

## Structure Guidance

### Suggested Flow
1. **Opening hook:** The frustration — "Claude said it created the file. But where is it?"
2. **The investigation:** How I started exploring with `view /` commands
3. **The map:** Key folders explained with table
4. **The gotcha:** Sandbox vs Filesystem MCP confusion
5. **The fix:** Specific prompts that work
6. **Two strategies:** Sandbox-first vs Local-first workflows
7. **Try it yourself:** Commands readers can run
8. **Quick reference:** Cheat sheet

### Opening Hook
Start with the specific frustration moment. First-person, relatable. No definitions.

### Closing CTA
"Now you know where Claude keeps its files. Go explore your own sandbox — and stop losing your work."

---

## Visual & Interactive Elements

### Screenshots Needed
1. Sidebar showing files in outputs folder
2. Result of `view /mnt/user-data/` showing structure
3. Example of Claude creating file "not in outputs" (the problem)

### Code Snippets for Article
```
view /
view /mnt/user-data/
view /home/claude/
```

### "Try It Yourself" Exercises
1. "Ask Claude: `view /mnt/user-data/` — what do you see?"
2. "Ask Claude to create a test file. Check: did it appear in sidebar?"
3. "If you have MCP configured, ask Claude to save via filesystem MCP specifically"

---

## Screenshot Flow (for Oleg to capture)

Create a fresh chat with Code Execution enabled. Run these in sequence:

```
Step 1: "Show me the root filesystem structure with view /"
Screenshot: The output showing available directories

Step 2: "Show me what's in /mnt/user-data/"
Screenshot: uploads/, outputs/ structure

Step 3: "Create a simple test.txt file with 'hello world' content"
Screenshot: Where Claude creates it (likely /home/claude/ or outputs/)

Step 4: "Show me /mnt/user-data/outputs/"
Screenshot: Verify file appears (or doesn't)

Step 5: Check sidebar
Screenshot: File appearing in download area

Step 6 (if MCP configured in Claude Desktop):
"Use filesystem MCP to save a file to ~/Desktop/test-mcp.txt"
Screenshot: Compare behavior — file goes to actual local disk
```

---

## References

### Official Documentation
- https://support.claude.com/en/articles/12111783-create-and-edit-files-with-claude (main reference)
- https://docs.claude.com/en/release-notes/claude-apps (timeline of features)

### Research Sources
- Personal investigation by author
- Simon Willison's analysis: https://simonwillison.net/2025/Sep/9/claude-code-interpreter/

### Background Context (for author reference, not for article)
- Artifacts launched June 2024, got highlight+edit September 2024
- "Analysis tool" (JS-based) launched October 2024
- Code Execution (Python/Node sandbox) replaced Analysis tool September 2025
- October 2025: Code Execution became default for paid plans, UI changed
- Users report highlight+edit feature may work differently now

### Competitor Articles
- None directly covering this topic (unique content opportunity)

---

**Brief created:** 2024-12-25
**Ready for:** @architect

---

# Outline

## Pre-Writing Notes

**Author:** henry
**Voice reference:** style-guides/henry-technical.md
**Word target:** 1200 words (range: 800-1500)
**Content type:** debugging-story

Key style points from Henry's guide:
- Opening: Start with problem/frustration, not definitions (Section 2)
- Sections: 150-300 words, paragraphs max 4 sentences (Section 2)
- Code ratio: 20-30% for debugging stories (Section 4)
- Closing: Practical next step, "Go build something." (Section 2)
- Voice: Direct, confident, first-person, "Here's the thing about..." (Section 1)

---

## Article Structure

### H1: Inside Claude's Sandbox: What Happens When Claude Creates a File
*Contains primary keyword: "claude file creation"*

---

### Opening

**Hook:**
> Did you know that every Claude conversation has its own sandbox container with a filesystem and persistent volumes? Understanding how they work and how Claude uses them gives you a significant advantage when working with this AI. While this is an internal part hidden under the hood, knowing how to work with it makes you more effective — and in some cases saves your time and work results.

**Transition:** "Let me show you what's actually happening under the hood."

---

### H2: The Filesystem Structure

**Purpose:** Show key directories and their purposes immediately

**Table:**
| Path | Contents | Persistence |
|------|----------|-------------|
| `/mnt/user-data/uploads/` | Files uploaded by user | Persistent |
| `/mnt/user-data/outputs/` | Downloadable files visible in sidebar | Persistent |
| `/home/claude/` | Claude's workspace | ⚠️ No guarantee of long-term persistence |
| `/mnt/skills/` | Built-in capabilities | Read-only |

**Pro Tip (callout box):**
> Files in `/home/claude/` can also be opened in the sidebar — just click on the file in the chat where tool output is displayed (file creation or editing).

---

### H2: What Happens When Claude Creates a File

**Purpose:** Explain the two-step process

**Steps:**
1. Claude creates the file in `/home/claude/`
2. Claude copies it to `/mnt/user-data/outputs/`

**Key insight:** There are actually TWO copies of the file.

---

### H2: Common Problems and How to Solve Them

**Disclaimer:** In simple scenarios Claude works well, but in more complex cases things may not go as planned. Don't panic about "where's my file?"

**Problems covered:**
- Claude created a file but didn't copy it to outputs
- Claude edited the version in `/home/claude/` instead of `/mnt/user-data/outputs/`
- How to see files you shared with Claude during the conversation
- ⚠️ Warning: Files in `/mnt/user-data/` are persistent, but be careful with `/home/claude/` — files there may disappear after some time

---

### H2: Walkthrough — The File Lifecycle in Action

> **@writer NOTE:** This section is a detailed walkthrough provided by Oleg. Transform into flowing narrative text while preserving ALL steps, observations, and warnings. The sequence and insights are essential — do not remove or reorder without approval. Screenshots are ready in assets folder.

**Purpose:** Demonstrate the full file lifecycle through a practical example — building a news compilation document.

---

#### Step 1: Creating an Internal File

**User prompt:**
```
Your task is to find and compile AI news into a single markdown document. Here's how we'll work:

**Workflow:**
1. I give you a topic or search query
2. You search the web, find relevant news, select the single best match, and append it to the document
3. We repeat steps 1-2 until I say "done"
4. You show me the complete document for final review

**Rules:**
- Only one news item per search — pick the most relevant result
- All items go into the same file (append, don't overwrite)
- For each item include: headline, source, date, and a 2-3 sentence summary

Let's start.

Search for: the funniest AI news from the last two months
```

**Screenshot:** `screenshots/s1.png`

**Key observation:** We deliberately did NOT specify where to create the file. We hinted that we plan to continue working with it and don't need it immediately. This simulates the scenario where Claude creates an internal working file without showing it to the user right away.

**Result:** Claude creates `ai-news-compilation.md` in `/home/claude/`. The file is NOT visible in the sidebar.

---

#### Step 2: Appending More Content

**User prompt:**
```
Now find the most important news about AI image generation for the last two months
```

**Screenshot:** `screenshots/s2.png`

**Key observation:** The file is still not visible in sidebar, but we can see Claude continues working with it using the `str_replace` tool (for editing/appending content).

---

#### Step 3: Viewing the Internal File (Option 1 — Click in Tool Output)

**Question:** What if we want to see the file contents at this point?

**Option 1:** Click on the filename in the tool output within the chat.

**Screenshot:** `screenshots/s3.png` — Arrow pointing to clickable filename in tool output

**Result:** The file opens in the sidebar preview panel.

**Screenshot:** `screenshots/s4.png` — File content visible, but NOT in sidebar file list

**Key observation:** The file opens and we can read its contents. However, it does NOT appear in the sidebar's file list — it's just a preview.

**⚠️ Warning:** Files in the internal sandbox (`/home/claude/`) are NOT persistent. They may be deleted when the container times out or the session ends. Be careful!

---

#### Step 4: Moving File to Outputs (Option 2 — Make Persistent)

**User prompt:**
```
move this file to /mnt/user-data/outputs/
```

**Screenshot:** `screenshots/s5.png`

**Result:** Claude uses bash tool with `mv /home/claude/ai-news-compilation.md /mnt/user-data/outputs/`. The file now appears in the sidebar's Artifacts list and is available for download.

**Key observation:** Since we MOVED (not copied) the file, Claude now has only ONE file to work with — in the outputs directory. We can continue adding news and see changes immediately in the sidebar.

---

#### Step 5: Continue Working (Happy Path)

**User prompt:**
```
Find the biggest Open Source AI related release for the last two months
```

**Result:** Claude appends to the same file. Since the file is now in `/mnt/user-data/outputs/`, changes are visible immediately in the sidebar.

---

#### Interlude: Understanding `present_files` Tool

**Important concept:** Claude has a `present_files` tool for finalizing work on a file. This is what Claude uses by default when completing work. It does the following:

1. **Copies** the file to `/mnt/user-data/outputs/`
2. Opens it immediately in the sidebar preview
3. Signals to Claude that work on this file is "complete" (though further modifications are still possible)

**The catch:** After `present_files`, there are now TWO copies of the file — one in `/home/claude/` and one in `/mnt/user-data/outputs/`.

**Verify this yourself:**
```
view /home/claude
```
and
```
view /mnt/user-data/outputs/
```

---

#### Step 6: The "Wrong File" Problem

**User prompt:**
```
The next task is to find the most performant AI coding agent released for the last two months
```

**Screenshot:** `screenshots/s7-wrong-file-edited.png`

**What happens:** Claude edits the file in `/home/claude/` (the working copy), NOT the one in `/mnt/user-data/outputs/`.

**Result:** We see in the chat that Claude made changes, but the file in the sidebar remains unchanged. This is the moment for panic — but not for us. Now we understand what's happening.

---

#### Step 7: The Fix

**User prompt:**
```
please move this file from /home/claude to /mnt/user-data/outputs/ (override the existing file)
```

**Screenshot:** `screenshots/s8.png`

**Result:** Claude copies the updated file to outputs, overwriting the old version. The sidebar now shows all the news items including the latest addition.

---

#### Summary: What We Learned

1. Claude creates working files in `/home/claude/` by default
2. Files only appear in sidebar when in `/mnt/user-data/outputs/`
3. You can view internal files by clicking on them in tool output
4. `present_files` creates a COPY — resulting in two files
5. Claude may edit the "wrong" file if duplicates exist
6. Solution: explicitly move/copy to outputs when needed

---

### H2: Quick Reference — Tools and Commands

**Purpose:** Hands-on reference for readers

**Key tools Claude uses internally:**
- `view` — view files and directory contents
- `str_replace` — edit files by replacing text
- `create_file` — create new files
- `bash_tool` — execute shell commands (ls, cp, mv, cat, etc.)
- `present_files` — make files available for download in sidebar

**What readers should try (natural language prompts):**
- "Show me what's in /mnt/user-data/" → triggers view
- "Create a file test.txt with 'hello world'" → triggers create_file
- "Run `ls -la /home/claude/`" → triggers bash
- "Copy test.txt to /mnt/user-data/outputs/" → triggers bash (cp)
- "Show me the file for download" → triggers present_files

**Note:** Tool names are internal implementation details. Users interact via natural language — Claude picks the right tool automatically.

**Reminder:** This requires Pro+ plan.

---

### H2: Two Strategies for File Workflows

**Purpose:** Explain Filesystem MCP as an additional method for file storage on external disk

**Strategy 1: Sandbox (built-in)**
- Files stay in Claude's container
- Pros: works out of the box, no setup needed
- Cons: potential persistence issues in `/home/claude/`

**Strategy 2: Filesystem MCP (external storage)**
- Files saved directly to your local disk
- Pros: true persistence, files in your project, version control
- Cons: requires MCP setup, Claude Desktop only

**Summary:** Sandbox for quick work, MCP for serious projects.

---

### H2: Fun Part — Experimenting

**The Two-Tab Experiment:**
1. Create a file with some text in Tab 1
2. Open the same chat in Tab 2
3. In Tab 2, ask to modify the file
4. Return to Tab 1, ask to show file contents
5. Contents match the changes from Tab 2
6. Claude is surprised — he doesn't see the modification command in Tab 1's history

→ Demonstrates that the sandbox is shared across all sessions of the same chat

---

### Closing

**Purpose:** Wrap up with practical takeaway

**Approach:** Henry-style direct ending. Short, no fluff.

**Must include:**
- One-sentence summary of key insight
- Clear CTA

---

## Word Count Breakdown

| Section | Words |
|---------|-------|
| Opening | 100 |
| The Filesystem Structure | 150 |
| What Happens When Claude Creates a File | 100 |
| Common Problems and How to Solve Them | 150 |
| **Walkthrough — The File Lifecycle in Action** | **450** |
| Quick Reference — Tools and Commands | 100 |
| Two Strategies for File Workflows | 150 |
| Fun Part — Experimenting | 120 |
| Closing | 80 |
| **Total** | **~1400** |

*Target: 1200-1500 (debugging story range) ✓*

> **Note:** Walkthrough section is longer due to code blocks and step-by-step format. Actual prose is ~300 words.

---

## Code Examples Plan

| Section | Type | Purpose | Lines |
|---------|------|---------|-------|
| The Filesystem Structure | Command | `view /mnt/user-data/` | 1 |
| The Filesystem Structure | Output | Directory listing | 4-5 |
| What Happens When Claude Creates a File | Code | File creation flow | 2 |
| Walkthrough Step 1 | Prompt | News compilation task prompt | 15 |
| Walkthrough Step 2 | Prompt | Add more news | 1 |
| Walkthrough Step 4 | Prompt | Move to outputs | 1 |
| Walkthrough Interlude | Commands | view /home/claude, view outputs | 2 |
| Walkthrough Step 6 | Prompt | Find coding agent news | 1 |
| Walkthrough Step 7 | Prompt | Move with override | 1 |
| Quick Reference | Commands | view, create, bash examples | 5-6 |
| Fun Part — Experimenting | Prompt | Two-tab experiment steps | 3-4 |

*Code ratio: ~25-30% (appropriate for debugging story with walkthrough)*

---

## Visual Elements Plan

| Element | Section | Description | File |
|---------|---------|-------------|------|
| Screenshot 1 | Walkthrough Step 1 | Claude creates internal file, not in sidebar | `s1.png` |
| Screenshot 2 | Walkthrough Step 2 | str_replace tool editing file | `s2.png` |
| Screenshot 3 | Walkthrough Step 3 | Clickable filename in tool output | `s3.png` |
| Screenshot 4 | Walkthrough Step 3 | File preview open, not in file list | `s4.png` |
| Screenshot 5 | Walkthrough Step 4 | File moved to outputs, visible in sidebar | `s5.png` |
| Screenshot 6 | Walkthrough Step 6 | Wrong file edited problem | `s7-wrong-file-edited.png` |
| Screenshot 7 | Walkthrough Step 7 | Fix — file moved/overwritten | `s8.png` |
| Table | The Filesystem Structure | Directory reference (paths, contents, persistence) | — |

### Screenshots Status

All screenshots are ready in `assets/claude-virtual-filesystem-guide/screenshots/`:

- [x] `s1.png` — Initial file creation
- [x] `s2.png` — Appending with str_replace
- [x] `s3.png` — Clickable filename (with arrow)
- [x] `s4.png` — File preview vs file list
- [x] `s5.png` — Move to outputs result
- [x] `s6-present-files.png` — (available, not used in walkthrough)
- [x] `s7-wrong-file-edited.png` — Wrong file edited
- [x] `s8.png` — Fix applied

**@writer:** Use relative paths like `screenshots/s1.png` when embedding images.

---

## SEO Notes

- [x] H1 contains: "Claude" + "File" (variant of primary keyword)
- [x] H2s with keywords: "Filesystem", "File Workflows"
- [x] First 100 words include: "Claude", "file", "created" (primary keyword area)
- [ ] Meta description: @writer to draft — focus on "where Claude saves files"

---

## Quality Gates for @writer

Before submitting draft:
- [ ] Opening starts with curiosity/professional interest, not frustration or confusion
- [ ] "Here's the thing..." or similar Henry phrase used
- [ ] All "Must include" items covered
- [ ] Word counts within range per section
- [ ] Table in The Filesystem Structure section present
- [ ] Code examples complete and accurate
- [ ] Two-tab experiment clearly explained in Fun Part section
- [ ] Closing has practical CTA, no fluff
- [ ] First-person voice throughout
- [ ] No forbidden phrases (see Henry guide)

---

**Outline created:** 2024-12-25
**Ready for:** @writer

---

# Validation Request

**Status:** Not required

This article is a technical tutorial/debugging-story based on personal investigation. All claims are verified through hands-on testing, not external sources.

**Technical claims verified by user (2026-01-06):**
- Filesystem structure (/mnt/user-data/, /home/claude/)
- File consistency across browser tabs
- Two-tab experiment behavior

**No external fact-checking needed** — proceed to @writer.

---

# Verified Facts

✅ **Проверено пользователем 2026-01-06:**

1. **Консистентность файлов между вкладками:**
   Файлы в `/home/claude/` доступны одновременно из любой вкладки браузера или Desktop версии с тем же чатом

2. **Структура /mnt/user-data/:**
   - `uploads/` — файлы, загруженные пользователем
   - `outputs/` — файлы, отображаемые в sidebar

3. **Доступ к файлам из /home/claude/:**
   Файлы из `/home/claude/` НЕ отображаются в списке sidebar, но доступны по клику на файл в выводе tool (создание, редактирование) прямо в чате

4. **Эксперимент с двумя вкладками:**
   - Создаём файл с текстом в Tab 1
   - Открываем тот же чат в Tab 2
   - В Tab 2 просим изменить файл
   - Возвращаемся в Tab 1, просим вывести содержимое
   - Содержимое соответствует изменению из Tab 2
   - Claude удивлён — он не видит команду изменения в истории Tab 1

   → Демонстрирует, что sandbox — общий для всех сессий одного чата

---

# Draft

See the article text in assets/claude-virtual-filesystem-guide/text.md - this is the actual ready to publish variant.

---

# Critique

## Review 1 (2026-01-07)

**Score:** 8.4/10 — PASS

### Summary

Draft технически solid. Контент уникальный — никто не документировал Claude sandbox structure так детально. Walkthrough section хорошо структурирован с screenshots. Основные проблемы: opening и closing не соответствуют Henry's style guide, недостаточно problem-focused моментов в тексте.

### Strengths

- Уникальный контент с реальной ценностью для читателя
- Технически точный и проверенный материал
- Хороший walkthrough с screenshots
- "Here's the thing about..." и другие Henry phrases используются
- Two-tab experiment — отличный "fun" финал

### Issues to Fix

1. **Opening — переписать**
   - Текущий: "Did you know that every Claude conversation runs in its own sandbox container with a real filesystem? Understanding how Claude creates, stores, and manages files gives you a significant advantage..."
   - Заменить на: "Did you know that every Claude conversation runs in its own sandbox container with a real filesystem? Understanding how it works gives you a significant advantage. Without this knowledge, it's easy to lose work or spend time debugging 'missing' files that aren't actually missing."
   - Затем: "Let me show you what's actually happening under the hood."

2. **Closing — переписать**
   - Текущий: "Go explore your own sandbox. Run `view /` and poke around. Understand the environment you're working in. Feel more confident and take control of your workflow."
   - Заменить на: "That's the filesystem. No magic, just directories and persistence rules. Now you know how it works — which means you can direct Claude precisely where to save, what to edit, and when to move files to outputs. Next time something seems off, you'll know exactly where to look. Go build something great with Claude. Your files will be exactly where you need them."

3. **После filesystem table — добавить**
   - После "Files in `/home/claude/` might disappear when the container times out."
   - Добавить: "Knowing this structure lets you navigate confidently and give Claude precise instructions — 'save to outputs,' 'move from home directory,' 'show me what's in uploads.'"

4. **Перед Interlude (present_files section) — добавить transition**
   - Перед "Claude has a `present_files` tool..."
   - Добавить: "This is where things get interesting — and where most confusion happens. When Claude uses `present_files`, you end up with two copies of the same file."

5. **После "Wrong File" problem — добавить контекст**
   - После "The new content exists only in `/home/claude/`."
   - Добавить: "This situation is common when working with complex multi-step scenarios. Claude doesn't always track which copy you care about — especially in longer conversations with many file operations."

6. **Перед "Why This Matters: Filesystem MCP" — переписать intro**
   - Текущий первый параграф слабый
   - Заменить на: "Understanding the internal filesystem is one thing. But when you add Filesystem MCP to the mix, there are now two filesystems Claude can work with — and this is where confusion multiplies. Claude might read from one and write to another without you noticing. I've been burned by this more than once: expecting a file on my local disk, finding it only in the sandbox, or vice versa. In these scenarios, explicit instructions matter."

### Minor Issues

- Некоторые параграфы в walkthrough — 5+ предложений, можно разбить
- Note box в начале можно оставить как есть (обсуждено, решили не трогать)

### Content Type Change

Изменено с `debugging-story` на `tutorial`. Walkthrough section читается как tutorial + experience share, это принято. Длина статьи остаётся ~1500 слов.

---

# Review Chat

@writer 07 Jan 2026. 19:45
Fixed:
- Opening: переписан с problem-focused формулировкой ("lose work", "debugging missing files")
- Closing: переписан в Henry-style ("No magic, just directories", "Go build something great")
- После filesystem table: добавлен контекст про precise instructions
- Transition перед present_files: "This is where things get interesting — and where most confusion happens"
- После Wrong File problem: добавлен контекст про complex multi-step scenarios
- Intro к Filesystem MCP: переписан с personal experience ("I've been burned by this more than once")

Passing to @editor for verification.

@seo 07 Jan 2026. 22:30
Applied SEO improvements to text.md:
- H2 headings: added keywords ("Claude's Sandbox", "Claude File Problems", "Claude File Commands")
- Image alt texts: optimized 7 screenshots with keyword-rich descriptions
- Body text: added target keywords naturally ("claude file creation", "claude sandbox environment")
- First 100 words: added long-tail phrase "where claude saves files"

Minimal changes, preserves readability.

---

# SEO Optimization

**Optimized:** 2026-01-07
**DataForSEO cost:** ~$0.06

## Keyword Strategy

| Type | Keyword | Volume | KD | Notes |
|------|---------|--------|----|----- |
| Primary | claude file creation | 30 | Low | Direct match, problem-focused |
| Secondary | claude sandbox | 70 | Low | Trending UP (10→210 in 2025) |
| Secondary | claude sandbox environment | 30 | Low | Specific, no confusion with Claude Code CLI |
| Secondary | claude mcp filesystem | 50 | Low | Addresses confusion point |
| Long-tail | where does claude save files | — | — | Reddit ranks #1, proves demand |

**Trend insight:** "claude sandbox" volume grew 20x in 2025 (from 10 to 210/month). Topic is gaining search interest.

## Title & Meta

**Current title:** Inside Claude's Sandbox: What Happens When Claude Creates a File ✓
- Contains primary keyword variant ("Claude" + "File")
- Curiosity-driven, specific
- Length: 64 chars (good)

**Meta description (NEW):**
> Learn where Claude saves files in its sandbox filesystem. Discover the /mnt/user-data/ structure, fix missing file issues, and master file workflows with this hands-on guide.

- 160 chars
- Includes: primary keyword, specific paths, problem-solution
- Matches search intent: "where does claude save files"

## Content Optimization

### Keyword Placement ✓
- [x] Primary keyword area: "Claude", "file", "created" in first 100 words
- [x] H1: Contains "Claude" + "File" + "Creates"
- [x] H2s include: "Filesystem Structure", "File Lifecycle", "File Workflows"
- [x] Natural density throughout walkthrough section

### Unique Value Proposition
Perplexity's response to our target query states:
> "Specific paths like /home or absolute roots are **not publicly documented**"

Our article documents exactly these paths (`/mnt/user-data/`, `/home/claude/`). This is the core differentiator — we provide information that doesn't exist elsewhere.

### Structure Strengths
- Table format for filesystem paths (scannable, snippet-friendly)
- Step-by-step walkthrough with screenshots
- "Try it yourself" commands for engagement
- Two-tab experiment as memorable takeaway

## SERP Feature Targeting

### Featured Snippet Opportunity: HIGH

**Target query:** "where does claude save files"

**Current SERP:** Reddit thread ranks #1, AI Overview answers about memory (not filesystem). Gap exists.

**Snippet-optimized content:**
The filesystem table in "The Filesystem Structure" section is already formatted for snippet capture:

| Path | Contents | Persistence |
|------|----------|-------------|
| `/mnt/user-data/uploads/` | Files you upload | Persistent |
| `/mnt/user-data/outputs/` | Downloadable files | Persistent |
| `/home/claude/` | Working directory | ⚠️ No guarantee |

**Recommendation:** No changes needed — table is well-structured.

### People Also Ask Opportunities

From SERP analysis:
- "How to download files from Claude AI?" — Partially covered in Quick Reference
- "Does Claude store memory?" — Not our topic (memory ≠ files)

**No action needed** — our focus is filesystem, not memory features.

### Video Carousel Present

Videos rank for "claude file creation". Consider:
- Future: Short video walkthrough of the two-tab experiment
- Not blocking for this article

## GEO (AI Search Optimization)

### Current AI Response Analysis

**Query tested:** "Where does Claude save files when using code execution?"

**Perplexity response highlights:**
- Mentions "sandboxed container environment"
- States paths "not publicly documented"
- References Anthropic docs and Simon Willison's analysis
- Does NOT mention specific paths like `/mnt/user-data/outputs/`

**Gap confirmed:** Our article provides the specific information AI systems currently cannot cite.

### Optimization for AI Citation

Article already follows GEO best practices:
- [x] Direct answers in section openings
- [x] Factual statements format ("Files in X persist. Files in Y don't.")
- [x] Structured data (tables, lists)
- [x] Specific paths and commands (citable facts)
- [x] Original investigation (unique source)

**Status:** GEO-optimized. Article provides citable facts (specific paths, persistence rules) that AI systems currently lack.

## Technical SEO

- [x] URL slug: `claude-virtual-filesystem-guide` (descriptive, keyword-relevant)
- [x] Image alt texts: Screenshots have descriptive names
- [ ] Schema markup: Recommend `HowTo` or `TechArticle` schema

## Competitor Gap Analysis

| Source | What They Cover | What They Miss |
|--------|----------------|----------------|
| Anthropic docs | High-level file creation feature | No internal paths documented |
| Simon Willison | Feature announcement analysis | No filesystem exploration |
| eesel.ai | Business use cases | No technical deep-dive |
| Reddit threads | User confusion questions | No systematic answers |

**Our unique position:** First comprehensive documentation of Claude's internal filesystem structure with reproducible experiments.

## Internal Linking

**From this article → future articles:**
- MCP setup guide (when published)
- Claude Desktop features overview (when published)

**To this article ← from other content:**
- Any article mentioning Claude file operations
- Claude productivity tips

## Priority Actions

1. **MEDIUM:** Add `HowTo` schema markup when publishing
2. **LOW:** Consider video content for two-tab experiment (future)

## Distribution Channels

**Primary:** r/ClaudeAI — high relevance, active community asking these questions
**Secondary:** Dev.to — tutorial format fits platform
**Tertiary:** Twitter/X — thread format with key insights

---

**SEO optimization complete.** Article ready for 6-ready/.

---

# Image Specs

**Created:** 2026-01-07
**Total images:** 2 (+ 9 existing screenshots)

## Image Strategy

**Style direction:** Technical, clean, developer-focused
**Color palette:** Blues and purples (Claude brand adjacent), with accent highlights for key elements

---

## 1. Hero Image

**Purpose:** Social sharing (OG), article header
**Type:** Conceptual illustration
**Dimensions:** 1200x630 (OG standard)
**Filename:** `hero.png`

**Concept:**
Isometric view inside a container/sandbox. The container is semi-transparent, showing internal structure. Inside: folder icons representing the key directories (`/mnt/user-data/`, `/home/claude/`). A file icon is mid-flight, moving from working area to outputs folder. Subtle grid pattern on the "floor" suggests technical environment.

**Key elements:**
- Semi-transparent container box (the sandbox)
- Folder structure visible inside
- File in motion (the "lifecycle" concept)
- Clean, minimal background

**Mood:** Technical but approachable, "peek under the hood" feeling

**Prompt draft:**
```
Isometric 3D illustration of a transparent container box representing a sandbox environment. Inside the container: minimalist folder icons arranged in a tree structure, one glowing file icon moving between folders. Color scheme: deep blue background, container with subtle purple glow, white and cyan folder icons, orange accent on the moving file. Clean flat design, no gradients, tech aesthetic. Empty space on left side for potential text overlay.
```

**Alt text:** Isometric illustration of Claude's sandbox container showing file movement between internal directories

---

## 2. Filesystem Structure Diagram

**Purpose:** Visualize directory structure and file flow
**Type:** Technical diagram
**Dimensions:** 1200x800 (fits article width, detailed content)
**Location:** After "The Filesystem Structure" section, complements the table
**Filename:** `filesystem-diagram.png`

**Concept:**
Architectural diagram showing the four key directories as boxes/containers. Arrows show possible file movements: upload → uploads folder, working file in /home/claude/, copy/move to outputs, outputs → sidebar (user access). Color-coded by persistence level.

**Must include:**
- `/mnt/user-data/uploads/` — labeled "Your uploads", green (persistent)
- `/mnt/user-data/outputs/` — labeled "Downloadable", green (persistent)
- `/home/claude/` — labeled "Working directory", yellow/orange (warning, temporary)
- `/mnt/skills/` — labeled "Read-only", gray
- Arrows showing file flow
- Sidebar icon representing user access point
- Persistence indicators (checkmark for persistent, warning for temporary)

**Style:** Flowchart/architecture diagram, flat design, labeled boxes

**Prompt draft:**
```
Technical architecture diagram showing file system structure. Four rectangular containers arranged in a layout: two green boxes labeled "/mnt/user-data/uploads/" and "/mnt/user-data/outputs/" on the right side, one orange/yellow box labeled "/home/claude/" in the center, one gray box labeled "/mnt/skills/" (smaller, read-only). Arrows showing file flow: dotted arrow from user icon to uploads, solid arrows between home/claude and outputs (bidirectional), arrow from outputs to a sidebar/download icon. Green checkmarks on persistent directories, warning triangle on /home/claude/. Clean flat design, white background, blue and purple accent colors for arrows. Labels in monospace font.
```

**Alt text:** Diagram showing Claude's filesystem structure with four directories and file flow paths between them

---

## Image Checklist

| # | Type | Priority | Filename | Status |
|---|------|----------|----------|--------|
| 1 | Hero Image | Must-have | `hero.png` | pending |
| 2 | Filesystem Diagram | Must-have | `filesystem-diagram.png` | pending |

---

## Generation Notes

**Hero image:**
- Leave space on left for potential title overlay (social templates)
- Container should feel "technical" but not cold
- The moving file is the focal point — represents the "lifecycle" theme

**Filesystem diagram:**
- Prioritize clarity over style
- Labels must be readable at article width
- Consider generating as SVG for crispness, or high-res PNG
- Warning indicator on `/home/claude/` is critical — main takeaway of the article

**Color reference:**
- Persistent = green (#22c55e or similar)
- Warning/temporary = orange (#f59e0b)
- Read-only = gray (#6b7280)
- Accents/arrows = blue (#3b82f6) or purple (#8b5cf6)

**Save to:** `assets/claude-virtual-filesystem-guide/`
