greptile: my earlier existence-check anchor was necessary but insufficient.
`rootDir` (= process.cwd() when FUSION_PROJECT_DIR is unset) drives ALL workspace
discovery (readWorkspacePatterns / listWorkspacePackageInfos /
packageHasVitestConfig). Launched from a package subdir, cwd-based discovery
found no packages, so decideExecutionPlan saw "no affected package", ran only the
gate, and exited successfully WITHOUT running the live changed package tests.
Fix the root cause: resolveRepoRoot() resolves the git toplevel as the fallback
(FUSION_PROJECT_DIR still the explicit override; cwd only when git can't report a
toplevel). This is correct from any cwd inside the repo, including a git worktree
(how the engine runs per-task verification). repoRootForExistence is now
redundant and removed; the existence check defaults back to rootDir.
Demonstrated: resolveRepoRoot() from packages/core (no FUSION_PROJECT_DIR) now
resolves the repo root and finds the workspace. +1 regression test. 121/121.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>