rojo/.cursor/plans/audit_ambiguous_paths_followup_00831072.plan.md

name	overview	todos	isProject
audit ambiguous paths followup	Production audit of the ambiguous-paths branch against origin/master. Documents critical round-trip issues, approved fixes, accepted limitations, and required regression tests for implementation in a follow-up Agent-mode session.	id content status fix-metadata-drift Update dedup cleanup rename flow to keep tree metadata/path indexes in sync pending	false

Ambiguous Paths Audit Fix Plan

This plan was generated by /audit from a Plan-mode session. Refer to .cursor/rules/atlas.mdc for full project standards.

Standards

These standards govern every fix in this plan. An implementer MUST read .cursor/rules/atlas.mdc before starting.

Round-Trip Identity (from atlas.mdc §Quality Standard)

Syncback (or two-way sync) writes a directory tree. Building an rbxl from that directory tree and forward-syncing it back must produce a bit-identical instance tree -- same names, same classes, same properties, same hierarchy, same ref targets. Any deviation is a bug.

CLI Syncback Parity (from atlas.mdc §Two-Way Sync Strategy)

Plugin-based sync must produce exactly the same filesystem output that atlas syncback would give for the same input. Byte-for-byte identical files, identical directory structures, identical naming. Any divergence is a bug until proven otherwise.

Code Quality (from atlas.mdc §Code Quality Standard)

DRY code that is easy to reason about and hard to get wrong. Small helper refactors are in scope; major pipeline redesign is deferred.

Context

Audited branch ambiguous-paths against origin/master using commit range origin/master..HEAD.

Primary findings:

• Critical path drift in dedup cleanup rename flow ([src/change_processor.rs](d:/UserGenerated/rojo/src/change_processor.rs)).
• Critical same-batch Ref target path synthesis mismatch for added instances ([src/web/api.rs](d:/UserGenerated/rojo/src/web/api.rs)).
• Critical ref-path post-processing strategy relies on global text replacement ([src/syncback/mod.rs](d:/UserGenerated/rojo/src/syncback/mod.rs), [src/syncback/fs_snapshot.rs](d:/UserGenerated/rojo/src/syncback/fs_snapshot.rs)).
• Known limitation accepted for this release: duplicate-named children under ProjectNode currently skipped in [src/snapshot_middleware/project.rs](d:/UserGenerated/rojo/src/snapshot_middleware/project.rs).
• Known limitation accepted for this release: greedy matcher is not globally optimal ([src/snapshot/matching.rs](d:/UserGenerated/rojo/src/snapshot/matching.rs), [src/syncback/matching.rs](d:/UserGenerated/rojo/src/syncback/matching.rs), [plugin/src/Reconciler/matching.lua](d:/UserGenerated/rojo/plugin/src/Reconciler/matching.lua)).

Fixes

Each fix below was approved by the user during the audit quiz. Implement in order.

Fix 1: Keep tree metadata consistent after dedup cleanup rename

• Status: Approved
• Finding: Step 2d / Step 8 (rename/delete interactions + VFS suppression)
• Files: [src/change_processor.rs](d:/UserGenerated/rojo/src/change_processor.rs)
• Problem: In dedup cleanup (~1073-1203), the code renames files (fs::rename) and suppresses both old/new paths, but does not update the renamed sibling's InstigatingSource::Path or metadata path indexes. Subsequent writes can target stale paths.
• Solution: After successful DedupCleanupAction::RemoveSuffix / PromoteLowest, locate the sibling instance being renamed, update its metadata source path and relevant path indexes in-memory, and keep suppression counters consistent with the updated path.
• Risk: Medium; touches tree mutation bookkeeping and rename lifecycle.
• Verify round-trip: Create duplicate siblings (Foo, Foo~1), delete Foo, ensure Foo~1 -> Foo rename occurs, then issue a property update to the survivor in same session and verify disk write targets new path and survives rebuild.
• Verify syncback parity: Compare output of two-way deletion flow to CLI syncback on equivalent tree state; both must produce the same remaining filename/meta layout.
• Tests required:
  • Rust integration test in [tests/tests/two_way_sync.rs](d:/UserGenerated/rojo/tests/tests/two_way_sync.rs) covering delete-triggered dedup cleanup followed by update.
  • Optional focused unit test around cleanup metadata path update helper in [src/change_processor.rs](d:/UserGenerated/rojo/src/change_processor.rs).

Fix 2: Build correct same-batch added Ref paths

• Status: Approved
• Finding: Step 2a / Step 10 (plugin->server wire format and write processing)
• Files: [src/web/api.rs](d:/UserGenerated/rojo/src/web/api.rs)
• Problem: added_paths map (~622-649) uses only slugified instance name; it omits middleware extension and dedup suffix. syncback_updated_properties then writes incorrect Rojo_Ref_* when target is newly added in same request (~2694-2706).
• Solution: Derive same-batch added target path using the same filesystem naming pipeline as syncback write (class/middleware extension + dedup suffix + directory-vs-file representation). Reuse/shared helper preferred to avoid divergence.
• Risk: Medium; affects same-request Ref persistence edge path.
• Verify round-trip: Send /api/write with add(target script/model) + update(ref property pointing to target) in one batch; verify persisted path includes correct segment (.server.luau, .model.json5, or dedup suffix) and resolves after rebuild.
• Verify syncback parity: Run equivalent scenario via CLI syncback fixture and compare written Rojo_Ref_* attribute string.
• Tests required:
  • Rust integration test in [tests/tests/two_way_sync.rs](d:/UserGenerated/rojo/tests/tests/two_way_sync.rs) for same-batch add+ref on file-backed and directory-backed targets.
  • Edge test for dedup suffix target (e.g., Foo~1).

Fix 3: Replace global ref-path text rewriting with attribute-scoped final paths

• Status: Approved
• Finding: Step 2a / Step 9 / Step 11h (round-trip identity, parity, determinism)
• Files: [src/syncback/mod.rs](d:/UserGenerated/rojo/src/syncback/mod.rs), [src/syncback/ref_properties.rs](d:/UserGenerated/rojo/src/syncback/ref_properties.rs), [src/syncback/fs_snapshot.rs](d:/UserGenerated/rojo/src/syncback/fs_snapshot.rs), [src/syncback/snapshot.rs](d:/UserGenerated/rojo/src/syncback/snapshot.rs)
• Problem: Syncback currently calls collect_referents(..., None) (~177) then performs broad post-hoc string replacement (~614-637) via fix_ref_paths (~456-492) across entire meta/model file text. This is not attribute-scoped and can alter unrelated strings.
• Solution: Feed definitive final paths into ref linking directly (e.g., pass populated final_paths to collect_referents) so Rojo_Ref_* attributes are written correctly first time. Remove or strictly confine generic text replacement path.
• Risk: Medium-high; touches syncback ref pipeline and ordering.
• Verify round-trip: Scenario with duplicate-named ref target and non-ref string property containing same substring as tentative path; ensure only Rojo_Ref_* changes and non-ref string is untouched.
• Verify syncback parity: Compare CLI syncback and two-way outputs for refs targeting dedup-suffixed instances; paths must be byte-identical.
• Tests required:
  • Rust integration test in [tests/tests/syncback_roundtrip.rs](d:/UserGenerated/rojo/tests/tests/syncback_roundtrip.rs) validating non-ref string preservation while refs are rewritten correctly.
  • Rust integration test in [tests/tests/two_way_sync.rs](d:/UserGenerated/rojo/tests/tests/two_way_sync.rs) for dedup-aware ref persistence without text rewrite side effects.

Fix 4: Add regression coverage for approved fixes

• Status: Approved
• Finding: Step 13 (missing coverage)
• Files: [tests/tests/two_way_sync.rs](d:/UserGenerated/rojo/tests/tests/two_way_sync.rs), [tests/tests/syncback_roundtrip.rs](d:/UserGenerated/rojo/tests/tests/syncback_roundtrip.rs), optionally helper fixtures under [rojo-test/syncback-tests](d:/UserGenerated/rojo/rojo-test/syncback-tests).
• Problem: Current tests do not fully guard the three approved bug classes.
• Solution: Add targeted regression tests tied to Fixes 1-3 and ensure they fail pre-fix and pass post-fix.
• Risk: Low.
• Verify round-trip: Covered by added integration scenarios.
• Verify syncback parity: Add assertions comparing resulting file paths/attribute values against expected CLI-format output.
• Tests required:
  • All tests listed under Fixes 1-3.
  • One deterministic re-run assertion (second run no changes) for affected scenarios.

Skipped Fixes

Skipped: ProjectNode duplicate-child handling rewrite

• Finding: Step 2d / Step 11k
• Problem: Duplicate-named children under ProjectNode are currently skipped with warnings ([src/snapshot_middleware/project.rs](d:/UserGenerated/rojo/src/snapshot_middleware/project.rs) around ~587-683).
• Reason skipped: User accepted as release limitation for now.

Skipped: Globally optimal matcher replacement

• Finding: Step 11h (determinism/assignment quality)
• Problem: Greedy assignment may produce suboptimal pairing in rare ambiguous groups.
• Reason skipped: User accepted greedy behavior for this release.

Accepted Limitations

• Limitation: ProjectNode duplicate-named children are skipped during syncback.
• Scenario: Under project-backed nodes, duplicate names are detected and omitted from child maps; warning logged.
• User decision: Accepted for this release.
• Mitigation: Keep explicit warning logs; add failing acceptance test (below) to track until fixed.
• Limitation: Greedy matching is not globally optimal.
• Scenario: Ambiguous duplicate groups can choose a local minimum causing rename churn.
• User decision: Accepted for this release.
• Mitigation: Add stress/failing test for known counterexample and keep deterministic tie behavior.

Deferred Refactors

• Consolidate filesystem-segment derivation into one shared helper used by [src/rojo_ref.rs](d:/UserGenerated/rojo/src/rojo_ref.rs), [src/snapshot/tree.rs](d:/UserGenerated/rojo/src/snapshot/tree.rs), and [src/web/api.rs](d:/UserGenerated/rojo/src/web/api.rs) to eliminate duplicate naming logic.
• Revisit optimal assignment algorithm for large ambiguous groups (major rewrite; out of current scope).

Test Plan

Rust Unit Tests (#[cfg(test)])

• Dedup cleanup metadata update helper behavior after rename (Fix 1).
• Added-path segment generation helper returns correct extension/suffix across middleware types (Fix 2).

Rust Integration Tests (tests/tests/)

• Delete base dedup name then update promoted sibling in same serve session; verify writes hit new path and persist after rebuild (Fix 1).
• Same /api/write request: add target + set Ref to target, verify persisted path includes expected extension/suffix (Fix 2).
• Ref rewrite safety: non-ref string fields are unchanged while Rojo_Ref_* gets final dedup path (Fix 3).

Lua Spec Tests (.spec.lua)

• No mandatory Lua-side changes for approved fixes; optional guard test for same-batch add+ref behavior if plugin-side helper touched.

Snapshot Tests (insta)

• Add or update syncback snapshot fixture showing final dedup-aware Rojo_Ref_* output without incidental string changes (Fix 3).

Failing Tests for Known Limitations

• ProjectNode duplicate-named child round-trip identity test asserting correct behavior (expected to fail until limitation removed).
• Ambiguous-group matching counterexample test asserting globally optimal pairing (expected to fail with greedy algorithm).

Test Rules

For bugs found and fixed

• Each approved bug fix must have a regression test that fails pre-fix and passes post-fix.

For missing coverage identified

• Add coverage in affected layer(s); investigate any unexpected failure as a potential additional bug.

For known limitations (Accepted Limitations section)

• Write correctness-asserting tests even if they fail now.
• Leave them failing (do not ignore), to serve as future acceptance criteria.

Scope

• Cover both persistence correctness (filesystem outputs) and in-memory tree consistency where applicable.

Final Step: Run CI

After implementing all approved fixes and tests, run /ci and require a clean pass before considering this plan complete.