That’s a great idea.

That’s a great idea. English is the universal language for sysadmins, and having this documented will help anyone running Mastodon on Coolify or Docker Compose.

Here is the professional documentation with clear comments and logic.

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# Guide: Changing Mastodon Character Limit (Docker/Coolify) Without Forking

This method allows you to increase the character limit (e.g., from 500 to 7500) while keeping your instance on the **official** Mastodon Docker images. This ensures easy updates and prevents the "merge hell" of custom forks.

### 1. Prepare Modified Files on the Host

Instead of editing files inside the container (which are wiped on every update), we create local copies on your server (e.g., in `/root/`).

#### A. Backend Validator (`/root/status_length_validator.rb`)

Change the `MAX_CHARS` constant to your desired limit.

```ruby
# frozen_string_literal: true
class StatusLengthValidator < ActiveModel::Validator
MAX_CHARS = 7500 # Set your limit here
URL_PLACEHOLDER_CHARS = 23
URL_PLACEHOLDER = 'x' * 23
# ... (keep the rest of the file as is)

```

#### B. Frontend Container (`/root/compose_form_container.js`)

Locate the line where the frontend fetches the character limit and set the fallback value to match your limit.

```javascript
// Search for 'max_characters' and change the fallback 500 to 7500
maxChars: state.getIn(['server', 'server', 'configuration', 'statuses', 'max_characters'], 7500),

```

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### 2. Update Docker Compose Configuration

In **Coolify** (or your `docker-compose.yml`), modify the **web** service. We use **Volumes** to "overlay" our custom files onto the container's filesystem.

```yaml
web:
image: 'tootsuite/mastodon:v4.5.5'
# 1. Environment Variables: Tell the API to report the new limit
environment:
- MAX_TOOT_CHARS=7500
- MAX_STATUS_CHARS=7500
# 2. Volume Mounts: Inject the modified files
volumes:
- 'mastodon_system:/opt/mastodon/public/system'
- '/root/status_length_validator.rb:/opt/mastodon/app/validators/status_length_validator.rb'
- '/root/compose_form_container.js:/opt/mastodon/app/javascript/mastodon/features/compose/containers/compose_form_container.js'

```

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### 3. Why This Works (v4.3+ Logic)

Modern Mastodon versions (v4.3, v4.4, v4.5+) are more dynamic:

* **Environment Variables**: Setting `MAX_TOOT_CHARS` forces the `/api/v1/instance` endpoint to report the new limit. Mobile apps (like Tusky or Ivory) read this and unlock the limit automatically.
* **Volumes**: Overlaying the Ruby file ensures the backend validates the length correctly. Overlaying the JS file ensures the web interface doesn't block the "Publish" button at 500 characters.

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### 4. Apply and Verify

1. **Save** the configuration in Coolify.
2. **Redeploy**: A simple restart is not enough; a redeploy is required to create the new volume mounts.
3. **Clear Browser Cache**: Use **Ctrl + F5** to ensure the new JavaScript is loaded.

#### Verification

To confirm the server is broadcasting the new limit, visit:
`https://your-domain.com/api/v1/instance`

Search for `"max_characters": 7500`. If you see it, the backend, frontend, and mobile apps are all synced.

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### Why this is better than a Fork:

* **Update-proof**: When a new Mastodon version is released, just click "Update" in Coolify. Your custom volumes will stay in place.
* **No Build Time**: You don't have to wait hours for a custom Docker image to build.
* **Clean**: You stay on the official security-patched images.

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**Is there anything else you'd like to add to this documentation, or maybe another part of Mastodon you want to optimize?**