conductor(track): Initialize data_structure_strengthening_20260606

Track + metadata + state + tracks.md registration for the type-aliases
refactor that follows the audit_weak_types.py findings (430 weak sites
across 29 of 61 files; 86% concentrated in 6 high-traffic files).

Key design decisions (per user approval):
- 10 TypeAlias definitions in src/type_aliases.py (Metadata, CommsLogEntry,
  CommsLog, HistoryMessage, History, FileItem, FileItems, ToolDefinition,
  ToolCall, CommsLogCallback).
- 1 NamedTuple (FileItemsDiff) for the _reread_file_items return.
- Mechanical replacement of 345 weak sites across 6 files (NOT 430; the
  remaining 85 are in 23 lower-impact files deferred to future tracks).
- scripts/audit_weak_types.py gains a --strict mode and a baseline file
  (scripts/audit_weak_types.baseline.json) so the count is enforced.
- 2 phases: aliases + 6-file replacement + audit baseline; NamedTuples
  + docs + archive.
- Honest about what's missing: TypedDict / @dataclass migration is a
  follow-up track (typed_dict_migration_20260606), not this one.
- Coexistence with the data_oriented_error_handling_20260606 track's
  Result[T] / ErrorInfo: the aliases are value-level (data types), Result
  is control-level (wrapper). They compose (Result[FileItems] is valid).
  No conflict.

Audit baseline:
- Pre-track: 430 weak sites, 0 strong patterns
- Target after Phase 1: ~60 weak sites (only the 23 lower-impact files)
- Top 4 unique type strings account for 86% of findings (4-6 aliases
  eliminate the bulk of the noise).

Not blocked by anything; can be executed independently of the other
pending tracks. Blocks typed_dict_migration_20260606 (the future Phase 2).

conductor/tracks.md

@@ -167,6 +167,10 @@ User review surfaced five outstanding UI issues, each previously attempted witho
    *Goal: Introduce Ryan Fleury's "errors are just cases" framework as a project convention. New `src/result_types.py` (ErrorKind enum, ErrorInfo dataclass, `Result[T]` with data + side-channel errors list, NilPath + NilRAGState sentinel singletons) and new `conductor/code_styleguides/error_handling.md` canonical reference. Refactor `src/mcp_client.py` ((p, err) tuples → Result; 30+ `assert p is not None` → nil-sentinel paths), `src/ai_client.py` (ProviderError exception → ErrorInfo dataclass; `_send_<vendor>()` → `_send_<vendor>_result()` returning `Result[str]`; `send()` marked `@deprecated`; new `send_result()` public API), and `src/rag_engine.py` (RAGEngine methods → Result returns). Update `conductor/product-guidelines.md` + `workflow.md` + `docs/guide_*.md` so the convention is documented and future plans can incrementally migrate the remaining `src/` files. **Blocked by** startup_speedup, test_batching_refactor, and qwen_llama_grok tracks. 5 phases: foundation+styleguide, mcp_client refactor, ai_client refactor (highest risk; ProviderError removal), rag_engine refactor, deprecation+docs+archive.*
    *Follow-up: [./tracks/public_api_migration_20260606/](./tracks/public_api_migration_20260606/) (planned; not yet specced) — removes the deprecated `ai_client.send()` and migrates all callers.*
 
+0f. [ ] **Track: Data Structure Strengthening (Type Aliases + NamedTuples)** `[track-created: <pending>]`
+   *Link: [./tracks/data_structure_strengthening_20260606/](./tracks/data_structure_strengthening_20260606/), Spec: [./tracks/data_structure_strengthening_20260606/spec.md](./tracks/data_structure_strengthening_20260606/spec.md), Plan: [./tracks/data_structure_strengthening_20260606/plan.md](./tracks/data_structure_strengthening_20260606/plan.md) (to be authored by writing-plans skill)*
+   *Goal: Improve AI-readability by naming 430 currently-anonymous `dict[str, Any]` / `list[dict[...]]` / `Tuple[...]` types. New `src/type_aliases.py` with 10 `TypeAlias` definitions (`Metadata`, `CommsLogEntry`, `CommsLog`, `HistoryMessage`, `History`, `FileItem`, `FileItems`, `ToolDefinition`, `ToolCall`, `CommsLogCallback`) and 1 `NamedTuple` (`FileItemsDiff`). Mechanical replacement of 345 weak sites across 6 high-traffic files: `src/ai_client.py` (139), `src/app_controller.py` (86), `src/models.py` (51), `src/api_hook_client.py` (32), `src/project_manager.py` (20), `src/aggregate.py` (17). Add `--strict` mode to the existing `scripts/audit_weak_types.py` (committed in 84fd9ac9; found the 430 sites) so it becomes a permanent CI gate that fails when new weak types are introduced. Generate `scripts/audit_weak_types.baseline.json` with the post-refactor count. 2 phases: aliases + 6-file replacement + audit baseline; NamedTuples + docs + archive. **Data-grounded**: the audit script is the source of truth; the count drops from 430 to ~60 (86% reduction) in the 6 high-traffic files. **Honest about what's missing**: 23 lower-impact files remain; TypedDict/dataclass migration is deferred to a follow-up track. 2-3 days work, 1-2 phases, low risk.*
+
 0b. [x] **Track: rag_phase4_stress_test_flake_20260606** — fixed 16412ad5
    *Status: 2026-06-06 — Surfaced during post-v2 verification. Resolved: real bug, NOT a test flake. Root cause: ChromaDB collection dimension mismatch across test runs. The persistent on-disk collection (`tests/artifacts/live_gui_workspace/.slop_cache/chroma_test_stress/`) was created by a previous run with Gemini embeddings (3072-dim); the current run uses local SentenceTransformers (384-dim). `index_file()` upserts silently corrupt the collection, then `search()` fails with `Collection expecting embedding with dimension of 3072, got 384` and the AI request never reaches 'done' status, timing out the 50*0.5s = 25s poll loop. Fix: `RAGEngine._init_vector_store` now calls `_validate_collection_dim` which inspects the first existing vector's dim, compares to the current provider's output, and recreates the collection on mismatch (with a stderr warning). Regression tests added: `test_rag_collection_dim_mismatch_recreates_collection` and `test_rag_collection_dim_match_preserves_collection` in `tests/test_rag_engine.py`. This also fixes a real user-facing bug: switching embedding providers in the GUI previously caused silent corruption. Commit 16412ad5.*
 0a. [ ] **Track: prior_session_test_harden_20260605** [superseded by live_gui_test_hardening_v2_20260605]