[djordjem88]

Summary

Requested reviewers: Nemanja Tesic (@nemanjatesic) and Elizabeth Craig (@ecraig12345).

Use an index cursor for the subgraph traversal queue and mark targets when enqueued. This avoids repeated front removal and duplicate inspection requests while retaining all dependency edges and their ordering.

Part of the broader Lage performance effort explored in #1238. This change is self-contained and can merge independently. It affects only subgraph extraction, not external-dependency resolution.

Validation

• Independent branch: target-graph suite passed (39 tests, 7 snapshots).
• Added coverage for shared dependencies, duplicate/empty/missing entries, repeated extraction, source-graph immutability, cycles, and missing dependencies.
• Full local CI passed during development of the combined series; this is not a claim about GitHub PR CI.
• Includes a Beachball patch change file.

[Copilot]

🟢 Approval recommended

No active review issues are reported for the subgraph-extraction optimization.

No open issues 🎉

What changed in this PR

Optimizes Lage’s subgraph extraction as a self-contained part of the performance effort in #1238. The change avoids redundant queue work while preserving dependency edges, ordering, and priorities; external-dependency resolution is unchanged.

Changes:

• Replaces front removal with an index cursor and deduplicates targets when enqueued.
• Adds coverage for shared dependencies, duplicate/empty/missing entries, repeated extraction, source-graph immutability, cycles, and missing dependencies.
• Includes a Beachball patch release note.

File	Description
packages/​target-graph/​src/​TargetGraphBuilder.ts	Uses cursor-based traversal and prevents duplicate enqueues.
packages/​target-graph/​src/​__tests__/​TargetGraphBuilder.test.ts	Adds regression coverage for graph semantics and edge cases.
change/​change-63a47ed4-130c-40f3-b16a-7cddba3f7b29.json	Records the target-graph performance improvement for a patch release.

_{Review effort: Max}