Track: revisit/deprecate MobiusBuilder's components_to_export once MobiusBuilder sees wider adoption

[titaiwangms]

Summary

PR #2456 added components_to_export to MobiusBuilder, which lets an Olive recipe declaratively select a subset of a multimodal model's components to export. Under the hood this is a thin wrapper around mobius's own ModelPackage.save(components=...) predicate filter (present in mobius since March 2026, unrelated to components_to_export itself).

This issue is a forward-looking tracking item, not an active bug: once MobiusBuilder sees wider adoption as the standard exporter for multi-component/VLM models (i.e. once we're no longer routing individual components like the decoder through a separate exporter such as ORT GenAI's native ModelBuilder), we should revisit whether Olive still needs its own components_to_export pass config, or whether it can be deprecated in favor of:

• Exporting the full composite model in one MobiusBuilder run (no partial export needed), and
• Using component-selection at a later stage instead (e.g. feat: add components_to_skip to OnnxBlockWiseRtnQuantization #2457's components_to_skip on downstream ONNX passes, or Add multi build support #2480's builds/select_components mechanism, if/when that lands), which already operate on a fully-formed composite model rather than needing to filter at export time.

Why this isn't done now

components_to_export currently exists because some components (notably the decoder) still need to go through a different exporter than MobiusBuilder (e.g. ORT GenAI's ModelBuilder) for that component alone, requiring MobiusBuilder to skip exporting it. Once MobiusBuilder itself can produce a decoder graph that's equivalent to (or supersedes) whatever the alternate exporter produces — i.e. once there's no longer a reason to route any component through a different exporter — the export-time filtering need mostly goes away, since a full export can just contain everything and downstream passes can select/skip what they need.

Suggested follow-up

• Re-evaluate once MobiusBuilder is the default/sole exporter path for at least the VLM recipes currently depending on split export (e.g. Qwen VL family recipes).
• If components_to_export is deprecated, keep components_to_skip (feat: add components_to_skip to OnnxBlockWiseRtnQuantization #2457) and/or the builds mechanism (Add multi build support #2480, if merged) as the supported way to scope per-component processing on an already-exported composite model.
• Not urgent; revisit when planning the next MobiusBuilder-adoption milestone.