shake incorrectly removes imports providing typeclass instances used by `inferInstanceAs`

[bryangingechen]

Prerequisites

• Check that your issue is not already filed:
  https://github.com/leanprover/lean4/issues
• Reduce the issue to a minimal, self-contained, reproducible test case.
  Avoid dependencies to Mathlib or Batteries.
• Test your test case against the latest nightly release, (tested against both v4.30.0-rc1 and nightly-2026-04-15`)

Description

Imports providing a typeclass instance are incorrectly removed by shake when the instance is resolved via
inferInstanceAs rather than by direct name reference. Minimal example provided in https://github.com/bryangingechen/shake-bug-inferInstanceAs .

Context

Found while running lake shake against mathlib4. Zulip thread.

Steps to Reproduce

1. git clone https://github.com/bryangingechen/shake-bug-inferInstanceAs && cd shake-bug-inferInstanceAs
2. lake build: succeeds
3. lake shake --fix
4. lake build: now fails

Expected behavior: Such imports should not be removed.

Actual behavior: Imports are removed, breaking the build.

Versions

v4.30.0-rc1

Impact

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