fly launch generates invalid .dockerignore with backslashes on Windows

[jamincan]

Issue: When running fly launch on Windows, the generated .dockerignore file contains backslashes (e.g., **\*.db). Deploys from the cli still work, but when deploying from github actions using superfly/flyctl-actions, the build fails with the error: #5 ERROR: error from sender: failed to match excludepatterns: syntax error in pattern. Manually changing the backslashes to slashes fixes the issue.

• Operating system: Windows 11 Pro 25H2
• Fly Version: 0.4.3

fly.toml

app = 'cfms'
primary_region = 'yyz'

[env]
  NODE_ENV = "production"
  DATABASE_URL = "file:/data/sqlite.db"
  BETTER_AUTH_URL = "https://cfms.fly.dev"

[http_service]
  internal_port = 3000
  force_https = true
  auto_stop_machines = true
  auto_start_machines = true
  min_machines_running = 0

[deploy]
  release_command = "pnpm run db:migrate"

[[mounts]]
  source = "data"
  destination = "/data"

[[vm]]
  memory = '1gb'
  cpus = 1
  memory_mb = 1024

Command output:

#5 [internal] load build context
#5 transferring context: 60B 0.0s done
#5 ERROR: error from sender: failed to match excludepatterns: syntax error in pattern
------
 > [internal] load build context:
------
Error: failed to fetch an image or build from source: error building: failed to solve: error from sender: failed to match excludepatterns: syntax error in pattern