resolveInternalSpecifier offered posix.join(dir, "index") as the
second candidate, ahead of every extension. With both dep.js and an
extensionless dep/index present, require("./dep") therefore resolved to
dep/index, a file that neither Node nor TypeScript ever selects.
Directory candidates now carry an extension. File and index ordering is
otherwise unchanged, so Node-validated cases such as dep/index.js
winning over dep.cjs keep their meaning.
Fixes#3381
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
Keep directory requests from becoming unresolved or pointing at sibling files
when constructing reference-source dependency graphs. Canonicalize index
candidates and preserve directory intent while retaining ordinary lookup rules.
Constraint: Preserve current TypeScript candidate objects and exact-before-Unicode lookup
Rejected: Reorder all file probes before index probes | Changes ordinary CommonJS candidate priority
Confidence: high
Scope-risk: narrow
Tested: Public CLI regression fails on base; focused reference and resolver suites pass; npm run check
Not-tested: Full suite on refreshed base; earlier full run had 12 baseline-reproduced failures
