[FEATURE] storing a lix file in a lix (sub-lixes)

[samuelstroschein]

Context

Storing a lix file in a lix is desired to enable "lix as file format" #182 usage with the lix file manager app.

Example usage

The lix file (.inlang) is stored in a lix itself.

- example.txt
- README.md
- frontend.inlang (THIS IS A LIX FILE)

The parent lix (example.txt, README.md) and sublix (frontend.inlang) should not interfere with each other to sustain portability.

The parent lix would need to know that the .inlang file is a lix and let the sub-lix handle it's own:

• change control
• sync
• file management

Checklist

• Does a workaround exist?
• Is this blocking adoption?

Leveraging lix as file format is severaly blocked 
by not being able to store lix files in lix. 

[samuelstroschein]

Example implementation

1. The parent lix needs to know that a file is a lix file irrespective of the file ending

Detecting that a file is a lix file could happen via the mime type. We could encode mime-type: application/lix in the lix file binary with the toBlob() function and subsequently query it with SQL.

await lix.db.insertInto("file")
  .values({ 
     path: "/frontend.inlang", 
     data: toBlob(project)
  })

const lixFiles = await db
  .selectFrom("file")
  // querying the file header in the binary for application/lix
  .where(
    sql`substr(data, 1, 4) = 'application/lix'`
  )
  .selectAll()
  .execute();

2. The lix SDK starts sub-processes for every detected lix file

We would want sub-lix files to be up to date, just like the parent lix. Hence, sub-lixes would need to start their own sync, change control, etc. In the future, we could optimize this to only start processes on-demand.

3. Apps can query across lix files

Using something like SQLite's attach mode could make querying across sub-lixes work https://sqlite.org/lang_attach.html.

const changes = lix.db.selectFrom("change").attach("frontend.inlang").selectAll() 

[samuelstroschein]

Minimal implementation idea

The lix FM app can be taken to simulate starting sub-processes for every lix and querying apps across lix-files by manually opening multiple lixes.

const lix = await openLix("parent.lix")

const sublix0 = await openLix({
  blob: await lix.db.selectFrom("file").where("path", "=", "/frontend.inlang")
}) 

const sublix1 = await openLix({
  blob: ...
})

...

Opening the sub-lixes manually simulates the desired behavior. We can potentially bypass the parents own change control by writing the sub-lixes with skipOwnChangeControl to the parent lix.