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claude-virtual-filesystem-guide

Inside Claude's Sandbox: What Happens When Claude Creates a File

henry

ready

2024-12-25

2026-01-07

tutorial

claude file creation

claude sandbox

claude sandbox environment

claude mcp filesystem

where does claude save files

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/claude-virtual-filesystem-guide/

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

Sandbox filesystem structure overview (key folders and their purposes)
What happens when Claude creates a file (step by step)
The /mnt/user-data/outputs/ → sidebar connection
Problem: Claude confusing internal sandbox vs Filesystem MCP (in Claude Desktop)
Solution: how to direct Claude to the right tool
Two strategies for file workflows (see below)
"Try it yourself" experiments for readers
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

Opening hook: The frustration — "Claude said it created the file. But where is it?"
The investigation: How I started exploring with view / commands
The map: Key folders explained with table
The gotcha: Sandbox vs Filesystem MCP confusion
The fix: Specific prompts that work
Two strategies: Sandbox-first vs Local-first workflows
Try it yourself: Commands readers can run
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

Sidebar showing files in outputs folder
Result of view /mnt/user-data/ showing structure
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

"Ask Claude: view /mnt/user-data/ — what do you see?"
"Ask Claude to create a test file. Check: did it appear in sidebar?"
"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:

Claude creates the file in /home/claude/
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:

Copies the file to /mnt/user-data/outputs/
Opens it immediately in the sidebar preview
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

Claude creates working files in /home/claude/ by default
Files only appear in sidebar when in /mnt/user-data/outputs/
You can view internal files by clicking on them in tool output
present_files creates a COPY — resulting in two files
Claude may edit the "wrong" file if duplicates exist
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:

Create a file with some text in Tab 1
Open the same chat in Tab 2
In Tab 2, ask to modify the file
Return to Tab 1, ask to show file contents
Contents match the changes from Tab 2
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/:

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

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

SEO Notes

H1 contains: "Claude" + "File" (variant of primary keyword)
H2s with keywords: "Filesystem", "File Workflows"
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:

Консистентность файлов между вкладками: Файлы в /home/claude/ доступны одновременно из любой вкладки браузера или Desktop версии с тем же чатом
Структура /mnt/user-data/:
- uploads/ — файлы, загруженные пользователем
- outputs/ — файлы, отображаемые в sidebar
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
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

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."
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."
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.'"
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."
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."
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 ✓

Primary keyword area: "Claude", "file", "created" in first 100 words
H1: Contains "Claude" + "File" + "Creates"
H2s include: "Filesystem Structure", "File Lifecycle", "File Workflows"
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.

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:

Direct answers in section openings
Factual statements format ("Files in X persist. Files in Y don't.")
Structured data (tables, lists)
Specific paths and commands (citable facts)
Original investigation (unique source)

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

Technical SEO

URL slug: claude-virtual-filesystem-guide (descriptive, keyword-relevant)
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

MEDIUM: Add HowTo schema markup when publishing
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/

40 KiB Raw Blame History Unescape Escape

Brief

Strategic Context

Why This Article?

Target Reader

Terminology Clarification (for article)

Success Metrics

SEO Strategy

Keywords

Search Intent

Competition

Unique Angle

Content Requirements

Core Question

Must Cover

Two File Workflow Strategies (new section)

Must NOT Cover

Note on Artifacts vs Files (sidebar box)

Unique Angle

Banatie Integration

Structure Guidance

Suggested Flow

Opening Hook

Closing CTA

Visual & Interactive Elements

Screenshots Needed

Code Snippets for Article

"Try It Yourself" Exercises

Screenshot Flow (for Oleg to capture)

References

Official Documentation

Research Sources

Background Context (for author reference, not for article)

Competitor Articles

Outline

Pre-Writing Notes

Article Structure

H1: Inside Claude's Sandbox: What Happens When Claude Creates a File

Opening

H2: The Filesystem Structure

H2: What Happens When Claude Creates a File

H2: Common Problems and How to Solve Them

H2: Walkthrough — The File Lifecycle in Action

Step 1: Creating an Internal File

Step 2: Appending More Content

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

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

Step 5: Continue Working (Happy Path)

Interlude: Understanding present_files Tool

Step 6: The "Wrong File" Problem

Step 7: The Fix

Summary: What We Learned

H2: Quick Reference — Tools and Commands

H2: Two Strategies for File Workflows

H2: Fun Part — Experimenting

Closing

Word Count Breakdown

Code Examples Plan

Visual Elements Plan

Screenshots Status

SEO Notes

Quality Gates for @writer

Validation Request

Verified Facts

Draft

Critique

Review 1 (2026-01-07)

Summary

Strengths

Issues to Fix

Minor Issues

Content Type Change

Review Chat

SEO Optimization

Keyword Strategy

Title & Meta

Content Optimization

Keyword Placement ✓

Unique Value Proposition

Structure Strengths

40 KiB

Raw Blame History

Interlude: Understanding `present_files` Tool