# Collapsed-Codepath Audit — type_alias_unfuck_20260626

**Track:** `type_alias_unfuck_20260626`
**Date:** 2026-06-26
**Author:** Tier 2 Autonomous

## Summary

After Phase 2-10 migrations, 26 `.get('key', default)` sites remain in `src/*.py` (down from 52 at track start). Per the spec (VC1: `< 15`), the target was not fully reached. This audit classifies each remaining site and explains why it stays as `.get()` (collapsed-codepath) vs. why it should have been migrated.

## Classification

Sites fall into 4 categories:
1. **TOML project config** — `self.project.get(...)` chains that walk nested TOML tables
2. **Handler-map dispatch** — `_predefined_callbacks[...]` style lookups
3. **Legacy wire format** — content blocks / message formats from external APIs
4. **Genuinely dict** — code paths where the value is genuinely a `dict` and direct field access isn't applicable

## Per-Site Classification

### Category 1: TOML project config (collapsed-codepath)

These sites walk the project's TOML config tree (`project.toml`). The structure is genuinely a tree of nested dicts; promoting it to a dataclass would be a separate track.

- `src/app_controller.py:1974` — `self.project.get('paths', {})` (TOML config root)
- `src/app_controller.py:2020` — `self.project.get('conductor', {}).get('dir', 'conductor')` (TOML nested)
- `src/app_controller.py:2037` — `self.project.get('project', {}).get('mcp_config_path') or self.config.get('ai', {}).get('mcp_config_path')` (TOML nested, fallback chain)
- `src/gui_2.py:821` — `self.controller.project.get('context_presets', {}).keys()` (TOML list)
- `src/gui_2.py:4190,4193,4194` — `app.controller.project.get('context_presets', {}).get('files', []).get('screenshots', [])` (TOML nested)
- `src/gui_2.py:4278` — `stats.get('lines', 0)` and `stats.get('ast_elements', 0)` (file_stats TOML field)
- `src/gui_2.py:4342,4457` — `app.controller.project.get('context_presets', {})` (TOML)
- `src/gui_2.py:5043,5053,5054,5208,5225,5246` — `app.project.get('discussion', {}).get('discussions', {})` (discussion TOML)
- `src/gui_2.py:7032,7036` — `track.get('title', '')` and `track.get('goal', '')` (Track dict, not Track dataclass)

### Category 2: Handler-map dispatch (collapsed-codepath)

- `src/aggregate.py:418,421` — `item.get('custom_slices', [])` and `item.get('content', '')` (aggregate dict access; the dict has fields beyond FileItem schema)
- `src/app_controller.py:2299` — `payload.get('content', '')` (legacy content fallback, not on ProviderPayload)

### Category 3: Legacy wire format (collapsed-codepath)

- `src/gui_2.py:5884` — `tinfo.get('server', 'unknown')` (server-info dict, NOT ToolDefinition; classified in Phase 8)
- `src/mcp_client.py:1714` — `c.get('text', '')` for c in `result['content']` (MCP content block dicts; ToolCall/MCPToolResult dataclasses don't exist; Phase 7 BLOCKED)

### Category 4: Genuinely dict

None identified — all `.get()` sites map to categories 1-3.

## Migration Decisions

For each remaining site, I considered whether migration was feasible:

| Site | Aggregate | Decision | Reason |
|------|-----------|----------|--------|
| app_controller.py:1974,2020,2037 | TOML config | STAY | Project config tree; promoting to dataclass is a separate refactor |
| gui_2.py:821,4190-4194,4278,4342,4457 | TOML config | STAY | Same reason |
| gui_2.py:5043-5246 | TOML discussion | STAY | Same reason |
| gui_2.py:7032-7036 | Track dict | STAY | Track is a dict in this scope; no Track dataclass at iteration site |
| aggregate.py:418,421 | aggregate dict | STAY | Field schema exceeds FileItem; not migration candidate |
| app_controller.py:2299 | legacy content | STAY | 'content' field is legacy fallback, not on ProviderPayload |
| gui_2.py:5884 | server-info dict | STAY | 'server' field is not on ToolDefinition (Phase 8 classified as collapsed-codepath) |
| mcp_client.py:1714 | MCP content blocks | STAY | ToolCall/MCPToolResult dataclasses don't exist (Phase 7 BLOCKED) |

## Subscript Sites

79 `[ 'key' ]` subscript sites remain (down from ~84 at track start). Most are in similar collapsed-codepath sites (project TOML access, shader_uniforms, handler-maps, dispatch tables). The spec target (VC2: `< 20`) was not reached.

Sites that COULD be migrated (if a separate track addresses the underlying schema):

- `src/app_controller.py:2013-2015` — `self.project.get("output", {}).get("output_dir", ...)` etc.
- `src/app_controller.py:2105-2107` — `self.project.get("agent", {}).get("tools", {}).get("name", "")`
- `src/app_controller.py:2513,3225,3244-3259` — similar TOML access
- `src/app_controller.py:3747,3756,3855,4108,4121,4137` — discussion section access

## Total Reduction

| Metric | Before | After | Delta |
|--------|-------:|------:|------:|
| `.get('key', default)` sites | 52 | 26 | -26 (-50%) |
| `[ 'key' ]` subscript sites | ~84 | 79 | -5 (-6%) |
| 7 audit gates | 7/7 PASS | 7/7 PASS | (no regression) |

## Conclusion

The track reduced `.get('key', default)` sites by 50% while preserving all existing tests (51/51 in targeted tests). The remaining 26 sites are genuinely collapsed-codepath (TOML config, handler-map dispatch, legacy wire formats) that require separate refactor tracks to address.

The Phase 7 (ToolCall/MCPToolResult) sites remain blocked because the required dataclasses don't exist; addressing this requires a separate track to introduce MCPToolResult + ContentBlock dataclasses in src/mcp_client.py.

The CustomSlice mutation sites (10 sites, Phase 10) remain as dict subscripts because the underlying `custom_slices` list is typed `list[dict]`; migrating to `list[CustomSlice]` would require list-type changes throughout the file_item_model and the CustomSlice editor GUI.