fix(ts): report correct paths for values after nested objects in deepCopyWithValidation - #4981

Assessment: Approve

Clean, well-scoped fix for the stale pathStack frame bug. The identity-based approach (matching the current parent via this and popping finished subtrees) is correct, and I traced the sibling, array, multi-level, and shared-reference cases to confirm paths resolve against the real parent. Node unit tests pass locally (42 tests); the browser-project failure is an unrelated missing-Playwright issue.

Nice job pinpointing the root cause and documenting the before/after behavior so clearly.

Thanks for the fix! Using this to find the parent object resolves the reported bug nicely. One request inline: two older wrong-path cases are on the lines this PR rewrites and are easy to fix now, could you please include them?

Thanks @opieter-aws for the review, and glad the parent-tracking approach resolves the reported bug! Quick heads-up: upstream history was restarted, so I rebased this branch onto current main (cf0c6aee); the same two changes are unchanged, only their hashes moved. Both older cases you flagged are now fixed in 1273ef3 (fix(ts): correct paths for numeric and empty-string keys in deepCopy validation), each with its own regression test.

1. Numeric-looking keys on plain objects

The bracket-notation decision now checks the holder (this) rather than the key alone, so brackets are used only for real arrays:

• { '0': fn }: previously reported value[0], now value.0
• { '42': fn }: previously reported value[42], now value.42
• array elements still use bracket notation (e.g. items[1]), unchanged

2. Real empty-string keys

The root check now distinguishes the initial replacer call (empty key, no frames on the stack) from a real '' property key, which is visited while its parent object is on the stack. A real empty-string key is appended as [''], so it can no longer collapse into the root:

• { '': { bad: fn } }: previously reported value.bad, now value[''].bad

Tests

src/types/__tests__/json.test.ts gained two cases covering both reports, and the full file passes:

vitest run --project unit-node src/types/__tests__/json.test.ts

Test Files  1 passed (1)
      Tests  44 passed (44)

The original stale-pathStack tests (sibling keys, array elements, and keys after multiple levels of nesting) all still pass, as do the StateStore tests that assert paths from the same validation code.

Assessment: Approve

Re-reviewed after the rebase and 1273ef3. The follow-up cleanly resolves both the numeric-key path and the empty-string-key path, and @opieter-aws's request is fully addressed.

Thanks for the thorough follow-up and the extra regression coverage.