[pierugo-dfinity]

Extend split-finder to split a subnet according to multiple load metrics, attempting to satisfy each of them. For example, splitting a subnet w.r.t instructions executed AND canisters installed (with --load-type instructions_executed canisters_installed). (Note: canisters_installed is only supported after #12038)

Each load can give a different epsilon to prioritize one over another.

The solver was actually already solving for multiple load types within solve_partition. This PR extends the CLI arguments to pass a list of all requested loads instead of a singleton.

[Copilot]

🟢 Approval recommended

No active review issues are recorded for the multi-metric subnet balancing changes.

No open issues 🎉

What changed in this PR

Extends the subnet split finder to balance multiple load types within a single partition while minimizing communication between the resulting subnets.

Changes:

• Adds multi-type --load-type arguments with optional per-type deviations, retaining --epsilon-load as the fallback.
• Loads aligned metric vectors and applies their balance constraints together.
• Adds tests for multi-metric balancing, per-type deviations, and argument validation.

File	Description
rs/​recovery/​subnet_splitting/​split_finder/​split_finder.py	Adds multi-type CLI parsing, shared balancing constraints, and clearer solver failure messages.
rs/​recovery/​subnet_splitting/​split_finder/​split_finder_test.py	Tests multi-metric loading, balancing, deviation limits, and CLI validation.
rs/​recovery/​subnet_splitting/​split_finder/​data_io.py	Returns a load vector for each requested metric.

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

The PR description advertises canisters_installed as a load type, but the CLI rejects it and the exported CSV lacks the column, so the metric must be implemented or the example corrected.

No open issues 🎉

1 previously missed issue

In code that hasn't changed since last review

Example load type is unsupported and absent from exported CSV

rs/​recovery/​subnet_splitting/​split_finder/​split_finder.py:113

The PR description's example --load-type instructions_executed canisters_installed is rejected here because canisters_installed is absent from LOAD_TYPES. The exported CSV also has no such column, so merely adding it to the choices would fail in the loader. Please either support it by deriving a vector of ones for current canister rows (as post_split_estimations.rs derives the installed count), without baseline subtraction, or update the description to use a supported metric.

_{Review effort: Balanced}