src/workspace/nested-dirs.ts — project-boundary set

Purpose

For each project, compute the set of other projects’ directories that live underneath it. Passed to cache/inputs.ts glob resolution so a parent project’s inputs.files can never reach into a nested project’s tree.

Public surface

export function computeNestedProjectDirs(
  entries: Array<Pick<ProjectEntry, 'name' | 'dir'>>,
): Map<string, string[]>

Returns Map<projectName, absoluteDirs[]>. Empty array for a project with no nested children.

Algorithm

Sort the entries by dir once, then for each project p scan forward: every dir sharing p.dir as a string prefix is contiguous in sorted order, and p’s descendants (p.dir + sep + …) are a run inside that block. A sibling whose name extends p.dir by a character that sorts below the separator (foo-utils beside foo; -, ., + and a space all sort before /) lands between p.dir and p.dir + sep, so the scan skips such interlopers and stops only on leaving the block — a plain break on the first non-descendant missed foo/nested behind foo-utils and silently broke the boundary. Near O(P log P) on real trees.

Why precompute

The result is consumed by every glob pass in every task during the run. Precomputing once lets cache/inputs.ts:resolveInputs operate in a hot loop without re-walking the project list.

Tests

tests/nested-dirs.test.ts (the function, the interloper class included) and tests/inputs-resolution.test.ts (the same class through the resolver); end to end, the “project boundary” cases in tests/orchestrator.test.ts create a parent + nested layout and verify that the parent’s inputs.files: ['**/*'] doesn’t pick up files from the nested project.

What this does NOT do

• Doesn’t enforce the boundary itself — cache/inputs.ts does, using the result of this function.
• Doesn’t resolve symlinks: the dirs are the discovered project directories as strings, and inputs come from git’s listing, which reports a link as a link.