Config template is created as an empty file

[steven-tk]

Issue Description

After a fresh install (or removing any existing ghostty config file) ghostty creates an entirely blank config file, failing to include the config-template. I've confirmed this on both my machines.

This issue is a regression from 1.2.3 to 1.3.0 and still present in current main.

The relevant function changed as part of the zig 0.15 migration:
It now creates a 4k buffer, writes the template to the buffer, but ends without a flush.

Possibly related: #13259 proposes handling empty configuration files differently, while this concerns Ghostty generating an empty file instead of writing the bundled template.

I used Codex:
a) to see if the template still exists & a function exists that tries to use the template
b) find the moment in history this behavior changed.

If confirmed I'd be happy to submit a PR if a one-liner is not too tedious to merge :)

Expected Behavior

Ghostty creates a new config file including the config-template for user orientation.

Actual Behavior

Ghostty creates an empty config file (0-byte) without the config-template content.

Reproduction Steps

1. Quit Ghostty or use a fresh install
2. Move any existing config file from default macOS locations:
   • ~/.config/ghostty/
   • ~/Library/Application Support/com.mitchellh.ghostty/
3. Open Ghostty.
4. Ghostty will generate a 0-byte config file in ~/Library/Application Support/com.mitchellh.ghostty/config.ghostty

Ghostty Logs

2026-08-13 01:32:42.687841+0200 0x206091   Error       0x0                  29472  0    ghostty: [com.mitchellh.ghostty:default] error reading optional config file, not loading err=error.FileIsEmpty path=/Users/steven/Library/Application Support/com.mitchellh.ghostty/config.ghostty

Ghostty Version

Ghostty 1.3.1

Version

  - version: 1.3.1
  - channel: stable
    Build Config
  - Zig version   : 0.15.2
  - build mode    : .ReleaseFast
  - app runtime   : .none
  - font engine   : .coretext
  - renderer      : renderer.generic.Renderer(renderer.Metal)
  - libxev        : kqueue

OS Version Information

Tahoe 26.6.1 (M1Pro) & Sequoia 15.7.7 (Intel)

(Linux only) Display Server

None

(Linux only) Desktop Environment/Window Manager

No response

Minimal Ghostty Configuration

No existing configuration.

Additional Relevant Configuration

No response

I acknowledge that:

• I have reviewed the FAQ and confirm that my issue is NOT among them.
• I have searched the Ghostty documentation and confirm there doesn't exist a configuration option that solves my issue.
• I have searched the Ghostty repository (both open and closed Discussions and Issues) and confirm this is not a duplicate of an existing issue or discussion.
• I have checked the "Preview" tab on all text fields to ensure that everything looks right, and have wrapped all configuration and code in code blocks with a group of three backticks (```) on separate lines.

[jcollie]

#13774