# BRIEFING — 2026-10-02T07:13:30Z

## Mission
Investigate root cause and formulate exact remediation strategy (code diffs and step-by-step instructions) for Critical Path Traversal in tools/serve_web_pc.py and Test Error Masking in tests/e2e/test_pc_desktop_client_e2e.py.

## 🔒 My Identity
- Archetype: teamwork_preview_explorer
- Roles: Server Security & Test Rigor Remediation Explorer
- Working directory: c:\Projects\FreeExile\.agents\teamwork\explorer_18_1
- Original parent: 75463099-5538-440a-8ff9-91c183526f7a
- Milestone: M18 - Forensic Remediation: Server Security & Test Rigor

## 🔒 Key Constraints
- Read-only investigation — do NOT implement code changes directly in project source
- Produce exact code diffs and step-by-step instructions in handoff.md for worker_18_1
- Ensure zero regression, watertight path containment, and zero console error allowance in tests
- Report back to parent via send_message

## Current Parent
- Conversation ID: 75463099-5538-440a-8ff9-91c183526f7a
- Updated: not yet

## Investigation State
- **Explored paths**:
  - `tools/serve_web_pc.py`
  - `tests/e2e/test_pc_desktop_client_e2e.py`
  - `tests/unit/test_pc_web_client.py`
  - `tests/unit/test_pc_web_client_layout.py`
  - `TEST_READY.md`
  - `c:\Projects\FreeExile\.agents\teamwork\auditor_18_1\handoff.md`
  - `c:\Projects\FreeExile\.agents\teamwork\ORIGINAL_REQUEST.md`
  - `c:\Projects\FreeExile\.agents\teamwork\orchestrator_16\PROJECT.md`
- **Key findings**:
  1. Path Traversal Root Cause: In `tools/serve_web_pc.py:162-200`, `clean_path.lstrip("/")` failed to sanitize `..` or Windows drive paths, and candidate paths were not checked for containment within `PC_DIR` or `WEBAPP_DIR`. Verified empirical leakage of `C:\Windows\win.ini` and `.git/config` with HTTP 200.
  2. Windows Drive Path Traversal: On Windows, `Path(base) / "C:/Windows/win.ini"` resolves to `C:\Windows\win.ini` because drive prefixes override base paths. URL decoding and checking for `:` as well as `..` provides robust defense in depth.
  3. Test Masking Root Cause: In `tests/e2e/test_pc_desktop_client_e2e.py:147, 151`, temporary error suppression filters (`"404"`, `"keys is not defined"`, `"hudOrbs"`, `"api/map"`) added during early development before fixes were implemented were never removed, masking any future regressions.
  4. Real Browser Runtime Verification: Ran headless Edge with zero filters on `test_tier1_zero_console_javascript_errors` — verified that with the current codebase, the browser loads completely cleanly with 0 console errors and 0 page errors. Purging the filters is 100% safe and required.
  5. Blast Radius Guard: `tools/serve_web_pc.py` is flagged HIGH risk by `blast_radius.py`. Worker must run `python tools/analysis/blast_radius.py --target tools/serve_web_pc.py --ack` before modifying the file to avoid getting blocked by the PreToolUse hook.
- **Unexplored areas**: None remaining.

## Key Decisions Made
- Formulated 4-layer defense in depth for `tools/serve_web_pc.py`: URL decode + `\` normalization -> explicit traversal/colon token rejection -> `Path.resolve()` canonicalization -> `Path.is_relative_to()` directory containment check + `is_file()` entity verification.
- Formulated exact diff for `tests/e2e/test_pc_desktop_client_e2e.py` to assert `len(errors) == 0` without suppressing `"404"`, `"keys is not defined"`, `"hudOrbs"`, or `"api/map"`.
- Added test recommendations for path traversal assertions to prevent regression.

## Artifact Index
- `c:\Projects\FreeExile\.agents\teamwork\explorer_18_1\DISPATCH.md` — Dispatch directives
- `c:\Projects\FreeExile\.agents\teamwork\explorer_18_1\BRIEFING.md` — Agent briefing & memory
- `c:\Projects\FreeExile\.agents\teamwork\explorer_18_1\progress.md` — Heartbeat and progress tracking
- `c:\Projects\FreeExile\.agents\teamwork\explorer_18_1\handoff.md` — Final handoff report with exact diffs