[ViktorHofer]

Extracted from #17621

To double check:

• The right tests are in and the right validation has happened. Guidance: https://github.com/dotnet/arcade/blob/main/Documentation/Validation.md

[Copilot]

Copilot review overview

🟡 Changes recommended

The critical fallback condition can affect unrelated frameworks and alter package dependency graphs.

Review effort: Lite
Findings: 1

Open (1)

• Scope prune data fallback to the synthesized current TFM · New

What changed in this PR

Refactors targeting-pack handling to support frameworks unknown to the installed SDK.

Changes:

• Uses the bundled framework as the targeting-pack baseline.
• Adds compatibility and prune-data fallback logic for newer frameworks.
• Updates framework-version handling.

File	Summary
src/​Microsoft.DotNet.Arcade.Sdk/​tools/​TargetingPacks.BeforeCommonTargets.targets	Refactors targeting-pack compatibility and fallback behavior; the fallback must be scoped to the current target framework.

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[Copilot]

Copilot review overview

🔵 Needs a closer look

Two unresolved moderate findings affect multi-targeting behavior and framework-version compatibility.

Review effort: Lite
Findings: 1

Open (1)

• Scope prune data fallback to the synthesized current TFM

[Copilot]

Copilot review overview

🟡 Changes recommended

Close the unclosed comment before the property declarations.

Review effort: Lite
Findings: 1

Open (1)

• Close unclosed XML comment to restore valid MSBuild XML · New

Resolved since last review (1)

• Scope prune data fallback to the synthesized current TFM

[Copilot]

Copilot review overview

🔵 Needs a closer look

Platform-qualified current TFMs are not covered by the current equality check, potentially causing restore or build failures.

Review effort: Lite
Findings: None

Previously missed (1)

In code that hasn't changed since last review

Support platform-qualified current TFMs in targeting pack bootstrap

src/​Microsoft.DotNet.Arcade.Sdk/​tools/​TargetingPacks.BeforeCommonTargets.targets:24

This exact equality excludes platform-qualified current TFMs such as net12.0-windows. Their inner builds leave _NeedsTargetingPackCurrentForUnknownTargetFramework unset, so the bootstrap SDK does not receive the synthesized current pack entries, maximum-version override, or pruning fallback and can still fail to restore/build; match the SDK's same-TFM-or-StartsWith(current + "-") condition instead.

[Copilot]

Copilot review overview

🔵 Needs a closer look

Restrict the fallback condition to the current targeting-pack framework build.

Review effort: Lite
Findings: None

[wtgodbe]

LGTM! We'd have to consume this in a dependency update to unblock #17621, right?