[ychampion]

Upgrading ESLint, @eslint/js and typescript-eslint together can fail against peer constraints from the outgoing plugin graph, even though the requested versions install together from scratch.

When an existing peer entry blocks placement, check whether its source still has a valid dependency path to a top node or a bundle.
Ignore obsolete entries after the existing replacement and clobber checks; retain constraints from shared consumers, roots/workspaces and bundles.
The existing placement machinery still handles removal and reevaluation.

Fixes #9324.

Validation:

• Regression tests cover installed and lockfile-only upgrades, transitive wrappers and stale cycles.
• Controls retain shared consumers, direct root dependencies, ordinary/root-owned bundles and incompatible target graphs.
• The reported ESLint version transition passes, followed by npm ls --all, a repeated install, npm ci and another clean dependency check.
• Full node . run test-all: all 17 suites pass, including Arborist at 100% coverage, lint and template checks.

Assisted by AI.