feat(script): migration path for Tabular Editor C# scripts — porting guide and tx script run #409

What are you trying to do?

Give teams moving from Tabular Editor 2/3 a migration path for the C# scripts and macros they already have: in CI (“run this script before deploy”), and from the TE community script library. This issue is about migration, not new scripting. For new automation, tx commands in a script already cover most cases (see below).

What do we do today?

• New automation is covered. tx interactive < changes.tx (feat(cli): tx interactive (alias tx shell), the live session REPL #347) runs a file of ordinary tx commands against one live session. The model loads once, begin / commit make the batch all-or-nothing, it undoes as one step, and batch mode stops at the first failure. Shell scripts with ls/find --paths-only piped into add / set / mv / rm / replace cover the rest.
• Existing TE scripts are not covered. They have to be rewritten by hand, and there is no guide for doing so. That is the main cost of switching from TE.
• C# scripting is out of scope for Epic: live model session — tx shell and tx serve #341 and Epic: tomix UI — browser companion, in-chat views, optional desktop app #355, so nothing else tracks it.

What would tx do?

1. Porting guide (do first, cheap)

A docs page, “Coming from Tabular Editor scripts”:

• The common TE script patterns side by side with their tx equivalents: set format strings, hide key columns, create time-intelligence measures, format DAX, add or rename display folders, generate measures from columns.
• A .tx script file example run through tx interactive, and a CI example.
• Mappings for TE macros: tx aliases and profiles.

Do this first. It shows which scripts actually need the C# runtime.

2. tx script run (C# compatibility)

tx script run fix-formats.csx
tx script run fix-formats.csx --selected "Sales/Measures/*"

• Roslyn scripting, with globals Model and Selected modelled closely enough on TE's API that common library scripts run without changes. Measure the coverage against the TE script library and publish it.
• Scripts run against a provider-neutral object API in Tomix.App, never raw TOM. Writes go through the normal mutation path, so the change journal, undo and --dry-run work, and in a live session a script is one transaction.
• Security: scripts are arbitrary code. They run only from a local file or stdin, never from a URL.

Acceptance criteria

• The porting guide covers at least the six patterns above, and its examples run as written against samples/.
• tx script run: an agreed set of TE community scripts runs unchanged, and a script that throws leaves the model unchanged.

Out of scope

• A new scripting DSL or batch file format: tx interactive with a script of tx commands already does this.
• TE2 command-line flag compatibility.