[djordjem88]

Summary

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

Replace repeated Array.shift() calls in external dependency resolution with an index that advances through the growing queue. Preserve FIFO traversal, the existing queued/processed sets, version-range resolution, resolved-version deduplication, and missing-package behavior.

Processed entries remain in the array until resolution returns. This avoids front-removal work at the cost of retaining those entries for the duration of the call.

Part of the broader Lage performance effort explored in #1238, following the queue-membership change already merged in #1248. This PR is based directly on current main and is independent of the other new performance PRs. Git file enumeration is deliberately excluded into its own PR.

Validation

• Independent branch based on main at cf155216; extracted source and test files exactly match the previously validated implementation.
• Final independent branch: all 26 backfill-hasher tests passed across six suites.
• Added a broad shared/cyclic dependency graph case asserting FIFO result order and missing-leaf handling. Existing range, scoped-package, cycle, deduplication, and invocation-isolation cases remain.
• Full local CI passed with the separate Git-enumeration optimization during implementation (30 successful targets, 91 cached/skipped, zero failures). This is not a claim about GitHub PR CI.
• Includes a Beachball patch note. No end-to-end speedup claim.

[Copilot]

🟢 Approval recommended

No active review issues block the dependency-queue traversal optimization.

No open issues 🎉

What changed in this PR

Reduces queue-processing overhead in Lage’s backfill-hasher while preserving existing dependency-resolution behavior.

Changes:

• Replaces repeated Array.shift() calls with cursor-based FIFO traversal, retaining processed entries until resolution completes.
• Adds a wide, shared/cyclic graph test covering traversal order and missing-dependency handling.
• Includes a Beachball patch release note.

File	Description
packages/​backfill-hasher/​src/​resolveExternalDependencies.ts	Advances a cursor through the growing dependency queue.
packages/​backfill-hasher/​src/​__tests__/​resolveExternalDependencies.test.ts	Adds coverage for breadth-first ordering, shared dependencies, cycles, and a missing leaf.
change/​change-35380e06-8e55-441c-9a55-f1b507d6b01e.json	Records the queue-traversal optimization as a patch release.

_{Review effort: Max}