diff --git a/.agents/phases/todo/84_docs_push_error_sanitization/00_phase.md b/.agents/phases/complete/84_docs_push_error_sanitization/00_phase.md
similarity index 100%
rename from .agents/phases/todo/84_docs_push_error_sanitization/00_phase.md
rename to .agents/phases/complete/84_docs_push_error_sanitization/00_phase.md
diff --git a/.agents/phases/todo/84_docs_push_error_sanitization/01_shared_sanitizer.md b/.agents/phases/complete/84_docs_push_error_sanitization/01_shared_sanitizer.md
similarity index 100%
rename from .agents/phases/todo/84_docs_push_error_sanitization/01_shared_sanitizer.md
rename to .agents/phases/complete/84_docs_push_error_sanitization/01_shared_sanitizer.md
diff --git a/.agents/phases/todo/84_docs_push_error_sanitization/02_apply_docs_push_and_llm.md b/.agents/phases/complete/84_docs_push_error_sanitization/02_apply_docs_push_and_llm.md
similarity index 100%
rename from .agents/phases/todo/84_docs_push_error_sanitization/02_apply_docs_push_and_llm.md
rename to .agents/phases/complete/84_docs_push_error_sanitization/02_apply_docs_push_and_llm.md
diff --git a/.agents/phases/todo/84_docs_push_error_sanitization/03_verify_and_commit.md b/.agents/phases/complete/84_docs_push_error_sanitization/03_verify_and_commit.md
similarity index 100%
rename from .agents/phases/todo/84_docs_push_error_sanitization/03_verify_and_commit.md
rename to .agents/phases/complete/84_docs_push_error_sanitization/03_verify_and_commit.md
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.err b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.md b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.md
new file mode 100644
index 0000000..683ab3b
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.md
@@ -0,0 +1,11 @@
+**Phase 84 — final verification pass: all green, no defects found**
+
+- Verified implementation: `app/core/errors.py` (verbatim lift of sync masker), `app/api/sync.py` alias import, docs-push 502 `detail=sanitize_error(str(exc))`, all five `llm.py` error sites sanitized; new/extended test pins in place
+- Tests: `uv run pytest` → **1714 passed, 0 failed**; targeted pins (new unit ×2 + integration ×1, existing 502 pin) → 13 passed; sync/git-sources regression → 67 passed
+- Coverage: `uv run pytest --cov=app --cov-report=term-missing` → **99%** (`app/core/errors.py` 100%, `app/rag/llm.py` 100%) — >90% met
+- E2E isolation: `uv run pytest tests/e2e/test_smoke.py -v --no-cov` → **3 passed**
+- Lint/types: `uv run ruff check .` → clean; `uv run pyright` → **0 errors**
+- Criteria: 502 masks `*****@`/never token + row untouched ✅; LLM base-URL masked, credential-free strings byte-identical ✅; `_CREDS_RE` only in `app/core/errors.py` (working-tree grep) ✅; full gate green ✅; `git diff --stat` limited to the 4 app files + 2 modified test files + 3 phase task files (untracked: new module, new unit test, complete/ dir, reports, audit plan) ✅
+- Commit/phase move left to the harness per instructions (task files already in `complete/`)
+- No deviations; nothing to fix
+- Next pending phase: **85_mobile_menu_gate_overlap**
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.validate b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.validate
new file mode 100644
index 0000000..2d4c368
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__00_phase.a1.validate
@@ -0,0 +1,85 @@
+........................................................................ [  4%]
+........................................................................ [  8%]
+........................................................................ [ 12%]
+........................................................................ [ 16%]
+........................................................................ [ 21%]
+........................................................................ [ 25%]
+........................................................................ [ 29%]
+........................................................................ [ 33%]
+........................................................................ [ 37%]
+........................................................................ [ 42%]
+........................................................................ [ 46%]
+........................................................................ [ 50%]
+........................................................................ [ 54%]
+........................................................................ [ 58%]
+........................................................................ [ 63%]
+........................................................................ [ 67%]
+........................................................................ [ 71%]
+........................................................................ [ 75%]
+........................................................................ [ 79%]
+........................................................................ [ 84%]
+........................................................................ [ 88%]
+........................................................................ [ 92%]
+........................................................................ [ 96%]
+..........................................................               [100%]
+=============================== warnings summary ===============================
+.venv/lib/python3.13/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain_of_reese/.venv/lib/python3.13/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.13.13-final-0 _______________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  178      0   100%
+app/api/chats.py                 110      0   100%
+app/api/config.py                  7      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                   50      0   100%
+app/api/git_sources.py           212      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            29      0   100%
+app/api/sync.py                   98      0   100%
+app/api/tokens.py                 28      0   100%
+app/config.py                    141      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              108      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      19      0   100%
+app/core/tokens.py                33      0   100%
+app/db.py                         21      0   100%
+app/main.py                       64      0   100%
+app/models.py                     94      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 222      0   100%
+app/rag/archive_upload.py        128      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              180      3    98%
+app/rag/llm.py                   217      0   100%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             150      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   232      0   100%
+--------------------------------------------------
+TOTAL                           3237     12    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+validation OK
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.err b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.md b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.md
new file mode 100644
index 0000000..a30c5d5
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.md
@@ -0,0 +1,18 @@
+All criteria verified. Final report:
+
+**Task 01 — shared sanitizer module + sync alias refactor: complete**
+
+- `app/core/errors.py` (new): owns `_CREDS_RE` (exact phase-32 pattern) + `sanitize_error()` (`sub("*****@")`), with module docstring covering SEC-08/SEC-13 audit basis, narrow-userinfo byte-identity contract, and the `*****@` replacement shape.
+- `app/api/sync.py`: local `_CREDS_RE`/`_sanitize_error` deleted; now `from app.core.errors import sanitize_error as _sanitize_error`; one-line module-docstring note added; now-unused `import re` removed. `_run_sync` failure path byte-identical; `git_sources.py`/`docs.py` alias imports untouched.
+- `tests/unit/test_error_sanitization.py` (new, 9 tests): single/multiple userinfo masking, SEC-08 git push-failure line (token masked, `fatal:`/`exit 128`/host intact), byte-identity pins (bare https URL, colon+space prose, email `owner@example.com` — pattern doesn't match it, pinned as unchanged, empty string), idempotence on all masked forms, and `sync_api._sanitize_error is sanitize_error` alias identity.
+
+Results:
+- `uv run pytest tests/unit/test_error_sanitization.py -v` → 9 passed
+- `uv run pytest tests/integration/test_git_sources_upload.py tests/integration/test_sync_api.py` → 44 passed (no test edits)
+- `uv run pytest --cov=app --cov-report=term-missing` → 1711 passed; `app/core/errors.py` 100%, app/ total 99%
+- `uv run ruff check .` → clean; `uv run pyright` → 0 errors
+- `grep -rn _CREDS_RE app/` → exactly one definition, in `app/core/errors.py`
+
+Decisions: none — verbatim lift per design block. No pre-existing defects found. No git commits made (left for harness).
+
+Next pending task: `.agents/phases/todo/84_docs_push_error_sanitization/02_apply_docs_push_and_llm.md`
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.validate b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.validate
new file mode 100644
index 0000000..bf0b47a
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__01_shared_sanitizer.a1.validate
@@ -0,0 +1,85 @@
+........................................................................ [  4%]
+........................................................................ [  8%]
+........................................................................ [ 12%]
+........................................................................ [ 16%]
+........................................................................ [ 21%]
+........................................................................ [ 25%]
+........................................................................ [ 29%]
+........................................................................ [ 33%]
+........................................................................ [ 37%]
+........................................................................ [ 42%]
+........................................................................ [ 46%]
+........................................................................ [ 50%]
+........................................................................ [ 54%]
+........................................................................ [ 58%]
+........................................................................ [ 63%]
+........................................................................ [ 67%]
+........................................................................ [ 71%]
+........................................................................ [ 75%]
+........................................................................ [ 79%]
+........................................................................ [ 84%]
+........................................................................ [ 88%]
+........................................................................ [ 92%]
+........................................................................ [ 96%]
+.......................................................                  [100%]
+=============================== warnings summary ===============================
+.venv/lib/python3.13/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain_of_reese/.venv/lib/python3.13/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.13.13-final-0 _______________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  178      0   100%
+app/api/chats.py                 110      0   100%
+app/api/config.py                  7      0   100%
+app/api/doc_drafts.py             93      0   100%
+app/api/docs.py                   50      0   100%
+app/api/git_sources.py           212      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            29      0   100%
+app/api/sync.py                   98      0   100%
+app/api/tokens.py                 28      0   100%
+app/config.py                    141      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              108      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      19      0   100%
+app/core/tokens.py                33      0   100%
+app/db.py                         21      0   100%
+app/main.py                       64      0   100%
+app/models.py                     94      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 222      0   100%
+app/rag/archive_upload.py        128      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              180      3    98%
+app/rag/llm.py                   216      0   100%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             150      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   232      0   100%
+--------------------------------------------------
+TOTAL                           3235     12    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+validation OK
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.err b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.md b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.md
new file mode 100644
index 0000000..d080ab6
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.md
@@ -0,0 +1,18 @@
+All green. Final report:
+
+**Phase 84, Task 02 — docs-push 502 + LLM error sanitization**
+
+Implemented:
+- `app/api/doc_drafts.py`: `push_doc_draft` 502 detail now `sanitize_error(str(exc))` (SEC-08); route + module docstrings updated to name the SANITIZED stderr
+- `app/rag/llm.py`: all five error f-strings (embed, chat×3, chat_stream) wrap `self.settings.llm_base_url` in `sanitize_error(...)` (SEC-13) — surrounding copy byte-identical
+- `tests/integration/test_doc_drafts_api.py`: new pin — faked `DocsPushError` with `bot:ghp_LEAKTOKEN@github.com` → 502 detail has `*****@github.com`, `exit 128`, `fatal: Authentication failed`, never `ghp_LEAKTOKEN`; row untouched
+- `tests/unit/test_llm_client.py`: new pins — embed + chat transport failures with `https://svc:topsecret@llm.local/v1` → masked `https://*****@llm.local/v1`, no `topsecret`; plus a byte-identical credential-free message assertion
+
+Results:
+- `uv run pytest tests/integration/test_doc_drafts_api.py -v` — 28 passed; `uv run pytest tests/unit/test_llm_client.py -v` — 57 passed (pre-existing error-string pins green unchanged)
+- `uv run pytest --cov=app --cov-report=term-missing` — full suite green, TOTAL 99% (>90%); doc_drafts.py / llm.py / errors.py 100%
+- `uv run pytest tests/e2e/test_smoke.py -v --no-cov` — 3 passed in isolation
+- `uv run ruff check .` — clean; `uv run pyright` — 0 errors
+- No deviations; diff limited to the four task files (task 01's files remain in the tree for the harness's atomic phase commit)
+
+Next pending task: `.agents/phases/todo/84_docs_push_error_sanitization/03_verify_and_commit.md`
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.validate b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.validate
new file mode 100644
index 0000000..2d4c368
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__02_apply_docs_push_and_llm.a1.validate
@@ -0,0 +1,85 @@
+........................................................................ [  4%]
+........................................................................ [  8%]
+........................................................................ [ 12%]
+........................................................................ [ 16%]
+........................................................................ [ 21%]
+........................................................................ [ 25%]
+........................................................................ [ 29%]
+........................................................................ [ 33%]
+........................................................................ [ 37%]
+........................................................................ [ 42%]
+........................................................................ [ 46%]
+........................................................................ [ 50%]
+........................................................................ [ 54%]
+........................................................................ [ 58%]
+........................................................................ [ 63%]
+........................................................................ [ 67%]
+........................................................................ [ 71%]
+........................................................................ [ 75%]
+........................................................................ [ 79%]
+........................................................................ [ 84%]
+........................................................................ [ 88%]
+........................................................................ [ 92%]
+........................................................................ [ 96%]
+..........................................................               [100%]
+=============================== warnings summary ===============================
+.venv/lib/python3.13/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain_of_reese/.venv/lib/python3.13/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.13.13-final-0 _______________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  178      0   100%
+app/api/chats.py                 110      0   100%
+app/api/config.py                  7      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                   50      0   100%
+app/api/git_sources.py           212      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            29      0   100%
+app/api/sync.py                   98      0   100%
+app/api/tokens.py                 28      0   100%
+app/config.py                    141      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              108      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      19      0   100%
+app/core/tokens.py                33      0   100%
+app/db.py                         21      0   100%
+app/main.py                       64      0   100%
+app/models.py                     94      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 222      0   100%
+app/rag/archive_upload.py        128      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              180      3    98%
+app/rag/llm.py                   217      0   100%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             150      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   232      0   100%
+--------------------------------------------------
+TOTAL                           3237     12    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+validation OK
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.err b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.md b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.md
new file mode 100644
index 0000000..4007990
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.md
@@ -0,0 +1,21 @@
+All gates verified. Every task-03 completion criterion is met in the working tree; no defects found in prior tasks' work.
+
+**Phase 84 gate report — task 03 (verify) complete**
+
+Implemented (by tasks 01–02, verified by me):
+- `app/core/errors.py` (new): `sanitize_error` — verbatim lift of the sync `user:pass@` masker
+- `app/api/sync.py`: local regex+function deleted, private alias import (callers `git_sources.py`/`docs.py` untouched)
+- `app/api/doc_drafts.py`: docs-push 502 detail runs through `sanitize_error` (SEC-08)
+- `app/rag/llm.py`: all five LLM error f-strings sanitize `llm_base_url` (SEC-13)
+- New/extended pins: `tests/unit/test_error_sanitization.py`, `test_llm_client.py` (mask + byte-identical), `test_doc_drafts_api.py` (502 masks `ghp_LEAKTOKEN`, row untouched)
+
+Gate results (all green):
+- `uv run pytest` → 1714 passed, exit 0 (regression anchors incl. sync/upload, doc-drafts, LLM)
+- `uv run pytest --cov=app --cov-report=term-missing` → `app/` TOTAL **99%** (>90% required)
+- `uv run pytest tests/e2e/test_smoke.py -v --no-cov` → 3 passed in isolation
+- `uv run ruff check . && uv run pyright` → clean (0 errors/warnings)
+- `grep -rn _CREDS_RE app/ scripts/` → only `app/core/errors.py`; diff scope limited to the 7 code/test files + phase files; NO `scripts/`, `docs_push.py`, `frontend/`, `pyproject.toml`/`uv.lock`
+
+Deviations (per harness executor rules, overriding task step 2–3): no `git add`/`commit` and no phase-dir move by me — all changes left in the working tree for the harness's one atomic `fix(security)` commit + todo→complete move.
+
+Next pending task: none in phase 84 (03 was last); next phase: `85_mobile_menu_gate_overlap`.
diff --git a/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.validate b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.validate
new file mode 100644
index 0000000..2d4c368
--- /dev/null
+++ b/.agents/reports/84_docs_push_error_sanitization/84_docs_push_error_sanitization__03_verify_and_commit.a1.validate
@@ -0,0 +1,85 @@
+........................................................................ [  4%]
+........................................................................ [  8%]
+........................................................................ [ 12%]
+........................................................................ [ 16%]
+........................................................................ [ 21%]
+........................................................................ [ 25%]
+........................................................................ [ 29%]
+........................................................................ [ 33%]
+........................................................................ [ 37%]
+........................................................................ [ 42%]
+........................................................................ [ 46%]
+........................................................................ [ 50%]
+........................................................................ [ 54%]
+........................................................................ [ 58%]
+........................................................................ [ 63%]
+........................................................................ [ 67%]
+........................................................................ [ 71%]
+........................................................................ [ 75%]
+........................................................................ [ 79%]
+........................................................................ [ 84%]
+........................................................................ [ 88%]
+........................................................................ [ 92%]
+........................................................................ [ 96%]
+..........................................................               [100%]
+=============================== warnings summary ===============================
+.venv/lib/python3.13/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain_of_reese/.venv/lib/python3.13/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.13.13-final-0 _______________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  178      0   100%
+app/api/chats.py                 110      0   100%
+app/api/config.py                  7      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                   50      0   100%
+app/api/git_sources.py           212      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            29      0   100%
+app/api/sync.py                   98      0   100%
+app/api/tokens.py                 28      0   100%
+app/config.py                    141      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              108      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      19      0   100%
+app/core/tokens.py                33      0   100%
+app/db.py                         21      0   100%
+app/main.py                       64      0   100%
+app/models.py                     94      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 222      0   100%
+app/rag/archive_upload.py        128      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              180      3    98%
+app/rag/llm.py                   217      0   100%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             150      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   232      0   100%
+--------------------------------------------------
+TOTAL                           3237     12    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+validation OK
diff --git a/app/api/doc_drafts.py b/app/api/doc_drafts.py
index 6a20135..cb49f95 100644
--- a/app/api/doc_drafts.py
+++ b/app/api/doc_drafts.py
@@ -26,8 +26,10 @@ triggers — commit + ``git push`` the draft's file to the
 :func:`app.core.docs_push.push_document`; success records
 ``status`` / ``branch`` / ``commit_sha`` on the row and returns
 ``DocDraftPushed``; 409 while unconfigured, 422 on a path that no
-longer passes the guard-rails, 502 on git failure with git's stderr
-in the detail — the row untouched).
+longer passes the guard-rails, 502 on git failure with the
+SANITIZED git stderr in the detail (credential ``user:pass@``
+userinfo masked by :func:`app.core.errors.sanitize_error` — phase
+84, SEC-08) — the row untouched).
 
 Every ``path`` (create, update **and** push) passes the shared
 :func:`validate_draft_path` guard, so no draft can ever be created,
@@ -45,6 +47,7 @@ from sqlalchemy.orm import Session
 from app.config import Settings, get_settings
 from app.core.auth import require_admin
 from app.core.docs_push import DocsPushError, push_document
+from app.core.errors import sanitize_error
 from app.db import get_db
 from app.models import DocDraft
 from app.schemas import DocDraft as DocDraftOut
@@ -251,11 +254,16 @@ def push_doc_draft(
     3. the stored ``path`` re-runs :func:`validate_draft_path` → 422
        on the first violated rule (a row must not be pushable into a
        bad path, whatever wrote it);
-    4. :class:`DocsPushError` → 502 with ``detail=str(exc)`` — git's
-       stderr, the ``GitSyncError`` → ``detail`` mapping from
-       :mod:`app.api.git_sources`. Only a SUCCESS mutates the row:
-       the failed push leaves ``status`` / ``branch`` / ``commit_sha``
-       exactly as found (no partial commit).
+    4. :class:`DocsPushError` → 502 with the SANITIZED git stderr in
+       the detail (phase 84, SEC-08): ``str(exc)`` runs through
+       :func:`app.core.errors.sanitize_error`, which masks any
+       ``user:pass@`` userinfo git's stderr may echo (a
+       ``BOR_DOCS_REPO`` URL with embedded credentials) — the failing
+       repo and git's reason stay readable, and the
+       ``GitSyncError`` → ``detail`` mapping from
+       :mod:`app.api.git_sources` is otherwise kept. Only a SUCCESS
+       mutates the row: the failed push leaves ``status`` / ``branch``
+       / ``commit_sha`` exactly as found (no partial commit).
 
     On success the row becomes ``status = "pushed"`` with the landed
     ``branch`` and ``commit_sha`` (must equal ``git rev-parse
@@ -283,7 +291,11 @@ def push_doc_draft(
             commit_message=f"docs: {row.title}",
         )
     except DocsPushError as exc:
-        raise HTTPException(status_code=502, detail=str(exc)) from None
+        # Phase 84 (SEC-08): git's stderr may echo the remote URL with
+        # embedded credentials — the RESPONSE is where the secret would
+        # leak, so it is sanitized here (the DocsPushError itself keeps
+        # carrying the full stderr for logs/inspection).
+        raise HTTPException(status_code=502, detail=sanitize_error(str(exc))) from None
     row.status = "pushed"
     row.branch = branch
     row.commit_sha = sha
diff --git a/app/api/sync.py b/app/api/sync.py
index 0a1b904..aabbb35 100644
--- a/app/api/sync.py
+++ b/app/api/sync.py
@@ -57,12 +57,15 @@ carries the phase-64 per-file progress — ``current_file`` (the
 ``files_done`` / ``files_total`` — null/0/0 before the import starts
 (clone/pull reports no file yet) and in terminal states, which clear
 ``current_file`` but keep the run's final counts.
+
+The ``failed`` state's ``error`` string is masked by the shared
+sanitizer — the ``user:pass@`` masker now lives in :mod:`app.core.errors`
+(imported here under the private name ``_sanitize_error``).
 """
 from __future__ import annotations
 
 import asyncio
 import logging
-import re
 from dataclasses import dataclass, field
 from datetime import UTC, datetime
 from pathlib import Path
@@ -72,6 +75,7 @@ from fastapi import APIRouter, Depends, HTTPException
 
 from app.config import get_settings
 from app.core.auth import require_admin
+from app.core.errors import sanitize_error as _sanitize_error
 from app.db import SessionLocal
 from app.rag.git_sources import effective_sources
 from app.rag.importer import ImportSummary, import_sources
@@ -89,20 +93,6 @@ router = APIRouter(
     dependencies=[Depends(require_admin)],  # phase 16 pattern: admin-only surface
 )
 
-#: ``user:pass@`` inside any error text (git stderr, endpoint URLs) —
-#: masked so a sync failure can never leak credentials into the UI.
-_CREDS_RE = re.compile(r"[A-Za-z0-9._~%*-]+:[A-Za-z0-9._~%*-]+@")
-
-
-def _sanitize_error(message: str) -> str:
-    """Mask credentials embedded in an error string (no secrets in the UI).
-
-    Git's stderr is otherwise surfaced verbatim (phase locked decisions) —
-    it names the failing repo and git's reason, which is what the admin
-    needs to fix things.
-    """
-    return _CREDS_RE.sub("*****@", message)
-
 
 @dataclass
 class SyncStatus:
diff --git a/app/core/errors.py b/app/core/errors.py
new file mode 100644
index 0000000..fa3d6e1
--- /dev/null
+++ b/app/core/errors.py
@@ -0,0 +1,57 @@
+"""Shared error-string sanitizer (phase 84 — audit SEC-08 / SEC-13).
+
+``sanitize_error`` masks ``user:pass@`` userinfo in an error string so
+no error surface ever ships an embedded credential into the UI, a
+response body, or an SSE frame. It is the verbatim lift of the phase-32
+sync masker (same regex, same ``*****@`` replacement — byte-identical
+behavior); ``app/api/sync.py`` keeps the private name ``_sanitize_error``
+as an alias import, and the docs-push 502 detail (SEC-08) and the LLM
+error messages (SEC-13) run through the same function.
+
+Audit basis (``.agents/remediation_plan.md``, security audit 2026-09-07):
+
+* SEC-08 (Medium) — the docs-push 502 surfaced git's stderr verbatim;
+  ``BOR_DOCS_REPO`` is documented as "any remote (URL or local path)",
+  so an ``https://user:token@host/...`` URL is a normal config shape,
+  and a failed push (revoked token, network) echoes the remote URL in
+  git's stderr straight into the browser and the logs. The sync path
+  already solved exactly this problem — the docs-push and LLM surfaces
+  simply never got the treatment.
+* SEC-13 (Low) — the LLM error f-strings interpolated
+  ``settings.llm_base_url`` raw; a base URL configured with embedded
+  credentials would echo into SSE ``error`` frames and logs. Same class
+  of leak, same fix.
+
+Contract (narrow userinfo-regex only — byte-identical for
+credential-free text):
+
+* Only the git/HTTP ``user:pass@`` userinfo shape is rewritten — a run
+  of userinfo characters, the separating colon, a second run, and the
+  ``@``. Ordinary text survives character for character: plain hosts,
+  ``https://host/...`` URLs without userinfo, prose with a colon +
+  space (``fatal: ...``), emails in prose (no colon userinfo run
+  before the ``@``). The existing sync / git-sources / LLM error-string
+  tests are the tripwire proving the move is behavior-identical.
+* The replacement shape is ``*****@`` — the existing sync copy, so
+  every already-pinned masked error stays byte-identical.
+* Idempotent for the masked forms the surfaces produce (sanitizing an
+  already-sanitized git/URL failure string is a no-op).
+"""
+from __future__ import annotations
+
+import re
+
+#: ``user:pass@`` inside any error text (git stderr, endpoint URLs) —
+#: the narrow userinfo run (git/HTTP convention) that carries
+#: credentials; everything else is left untouched.
+_CREDS_RE = re.compile(r"[A-Za-z0-9._~%*-]+:[A-Za-z0-9._~%*-]+@")
+
+
+def sanitize_error(message: str) -> str:
+    """Mask credentials embedded in an error string (no secrets in the UI).
+
+    Git's stderr is otherwise surfaced verbatim (the admin needs the
+    failing repo and git's reason to fix things) — only the ``user:pass@``
+    userinfo shape is rewritten, to ``*****@``.
+    """
+    return _CREDS_RE.sub("*****@", message)
diff --git a/app/rag/llm.py b/app/rag/llm.py
index b8edcf1..cde16a7 100644
--- a/app/rag/llm.py
+++ b/app/rag/llm.py
@@ -29,6 +29,7 @@ from openai import AsyncOpenAI, AsyncStream
 from openai.types.chat import ChatCompletionChunk, ChatCompletionMessageParam
 
 from app.config import Settings, get_settings
+from app.core.errors import sanitize_error
 
 if TYPE_CHECKING:
     # Phase 71: the filter type is only needed for typing (the module
@@ -285,7 +286,11 @@ class LLMClient:
                 raise
             except Exception as e:  # noqa: BLE001 — wrap transport-level failures
                 raise EmbeddingError(
-                    f"embeddings request to {self.settings.llm_base_url} failed: {e}"
+                    # Phase 84 (SEC-13): a base URL configured with
+                    # embedded ``user:pass@`` credentials must not reach
+                    # the error string — sanitized at construction.
+                    f"embeddings request to {sanitize_error(self.settings.llm_base_url)} "
+                    f"failed: {e}"
                 ) from e
             self.embed_batches += 1
             self._check_dims(vecs)
@@ -324,18 +329,20 @@ class LLMClient:
             raise
         except Exception as e:  # noqa: BLE001 — wrap transport-level failures
             raise LLMError(
-                f"chat completion from {self.settings.llm_base_url} failed: {e}"
+                # Phase 84 (SEC-13): sanitize the base URL (see embed).
+                f"chat completion from {sanitize_error(self.settings.llm_base_url)} "
+                f"failed: {e}"
             ) from e
         if not resp.choices:
             raise LLMError(
-                f"chat completion from {self.settings.llm_base_url} "
+                f"chat completion from {sanitize_error(self.settings.llm_base_url)} "
                 "returned no choices"
             )
         content = resp.choices[0].message.content
         if content is None or not content.strip():
             raise LLMError(
-                f"chat completion from {self.settings.llm_base_url} returned "
-                "empty content — refusing to store a silent summary"
+                f"chat completion from {sanitize_error(self.settings.llm_base_url)} "
+                "returned empty content — refusing to store a silent summary"
             )
         return content.strip()
 
@@ -483,7 +490,10 @@ class LLMClient:
         except LLMError:
             raise
         except Exception as e:  # noqa: BLE001 — wrap transport-level failures
-            raise LLMError(f"chat stream from {self.settings.llm_base_url} failed: {e}") from e
+            # Phase 84 (SEC-13): sanitize the base URL (see embed).
+            raise LLMError(
+                f"chat stream from {sanitize_error(self.settings.llm_base_url)} failed: {e}"
+            ) from e
         finally:
             # Phase 48: deterministic teardown — whenever ``create()``
             # succeeded, close the endpoint's stream on every subsequent
diff --git a/tests/integration/test_doc_drafts_api.py b/tests/integration/test_doc_drafts_api.py
index ded1243..b4a2054 100644
--- a/tests/integration/test_doc_drafts_api.py
+++ b/tests/integration/test_doc_drafts_api.py
@@ -23,7 +23,9 @@ import pytest
 from fastapi.testclient import TestClient
 from sqlalchemy import select, text
 
+import app.api.doc_drafts as doc_drafts
 from app.config import Settings, get_settings
+from app.core.docs_push import DocsPushError
 from app.main import app as fastapi_app
 from app.models import DocDraft
 
@@ -483,6 +485,65 @@ def test_push_non_repo_dir_returns_502_with_git_stderr(
     assert body["commit_sha"] is None
 
 
+def test_push_502_detail_masks_git_stderr_credentials(
+    admin_client: TestClient,
+    db,
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Phase 84 (SEC-08): a ``DocsPushError`` whose git stderr carries a
+    ``user:pass@`` remote URL (a ``BOR_DOCS_REPO`` configured with
+    embedded credentials) → the 502 detail is the SANITIZED stderr — the
+    token never reaches the browser or the logs, while the failing repo
+    and git's reason stay readable; the row is untouched (only a success
+    mutates). ``push_document`` is monkeypatched, so no real git is
+    needed."""
+
+    def failing_push(**kwargs: Any) -> tuple[str, str]:
+        raise DocsPushError(
+            "git push origin bor-docs failed (exit 128): "
+            "fatal: Authentication failed for "
+            "'https://bot:ghp_LEAKTOKEN@github.com/owner/docs.git/'"
+        )
+
+    monkeypatch.setattr(doc_drafts, "push_document", failing_push)
+    fastapi_app.dependency_overrides[
+        get_settings
+    ] = lambda: _settings(
+        docs_repo="/nonexistent/docs.git",  # configured — push_document is faked
+        docs_branch=DOCS_BRANCH,
+        docs_base_branch=BASE_BRANCH,
+        docs_work_dir=str(tmp_path / "docs-workdir"),
+    )
+    created = _create(admin_client)
+    try:
+        r = admin_client.post(f"/api/doc-drafts/{created['token']}/push")
+    finally:
+        fastapi_app.dependency_overrides.pop(get_settings, None)
+
+    assert r.status_code == 502
+    detail = r.json()["detail"]
+    # The credential is masked to the sync masker's shape ...
+    assert "*****@github.com" in detail
+    assert "ghp_LEAKTOKEN" not in detail
+    # ... but the failure context stays readable (the GitSyncError →
+    # detail mapping, otherwise kept).
+    assert "exit 128" in detail
+    assert "fatal: Authentication failed" in detail
+    assert "owner/docs.git" in detail
+    # The row is untouched (status/branch/commit_sha as found).
+    body = admin_client.get(f"/api/doc-drafts/{created['token']}").json()
+    assert body["status"] == "draft"
+    assert body["branch"] is None
+    assert body["commit_sha"] is None
+    row = db.execute(
+        select(DocDraft).where(DocDraft.token == uuid.UUID(created["token"]))
+    ).scalars().one()
+    assert row.status == "draft"
+    assert row.branch is None
+    assert row.commit_sha is None
+
+
 def test_push_unknown_token_returns_404(
     admin_client: TestClient, docs_push_settings: Settings
 ) -> None:
diff --git a/tests/unit/test_error_sanitization.py b/tests/unit/test_error_sanitization.py
new file mode 100644
index 0000000..d37f413
--- /dev/null
+++ b/tests/unit/test_error_sanitization.py
@@ -0,0 +1,119 @@
+"""Unit tests: the shared error-string sanitizer (phase 84, task 01).
+
+``app.core.errors.sanitize_error`` is the verbatim lift of the phase-32
+sync masker — a NARROW ``user:pass@`` userinfo regex (git/HTTP
+convention) with the ``*****@`` replacement. These pins fix both sides
+of the contract:
+
+* masking — every pinned ``user:pass@`` occurrence is rewritten to
+  ``*****@`` (a single userinfo, two in one string, and one inside a
+  realistic git push-failure line — where ``fatal:`` / ``exit 128`` /
+  the host survive);
+* byte-identity — credential-free text (a bare https URL without
+  userinfo, prose with a colon + space, a plain email, the empty
+  string) comes back unchanged, character for character;
+* idempotence — sanitizing an already-sanitized (masked) string is a
+  no-op.
+
+Plus the refactor pin: ``app.api.sync._sanitize_error`` is the shared
+function under the private alias name (the phase-32 callers —
+``app/api/git_sources.py``, ``app/api/docs.py`` — see the identical
+function through the import).
+"""
+from __future__ import annotations
+
+import app.api.sync as sync_api
+from app.core.errors import sanitize_error
+
+TWO_USERINFO = "https://alice:secret1@repo.example.com/a.git and https://bob:secret2@repo.example.com/b.git"
+GIT_PUSH_FAILURE = (
+    "git push failed (exit 128): fatal: Authentication failed for "
+    "'https://bot:tok@github.com/o/r.git/'"
+)
+
+# --- The masked forms (the regex must fire) --------------------------------
+
+
+def test_masks_single_userinfo_in_url() -> None:
+    """The canonical shape: ``user:pass@`` → ``*****@``, host intact."""
+    assert sanitize_error("https://user:pass@host/repo.git") == "https://*****@host/repo.git"
+
+
+def test_masks_every_userinfo_occurrence() -> None:
+    """Two userinfo runs in one string → both masked, nothing else touched."""
+    masked = sanitize_error(TWO_USERINFO)
+    assert masked == "https://*****@repo.example.com/a.git and https://*****@repo.example.com/b.git"
+    assert "secret1" not in masked
+    assert "secret2" not in masked
+
+
+def test_masks_token_in_git_push_failure_line() -> None:
+    """The SEC-08 shape: git's auth-failure stderr with a token-bearing
+    remote URL → the token is masked, the actionable context survives."""
+    masked = sanitize_error(GIT_PUSH_FAILURE)
+    assert masked == (
+        "git push failed (exit 128): fatal: Authentication failed for "
+        "'https://*****@github.com/o/r.git/'"
+    )
+    assert "tok" not in masked
+    assert "exit 128" in masked  # the reason survives
+    assert "fatal:" in masked
+    assert "github.com/o/r.git" in masked  # host + repo path survive
+
+
+# --- The byte-identity contract (credential-free text) ---------------------
+
+
+def test_plain_url_without_userinfo_is_unchanged() -> None:
+    """A bare https URL (no userinfo) plus a realistic git failure line
+    → byte-identical."""
+    message = (
+        "git push failed (exit 128): fatal: repository "
+        "'https://github.com/owner/repo.git/' not found"
+    )
+    assert sanitize_error(message) == message
+
+
+def test_prose_with_colon_and_space_is_unchanged() -> None:
+    """Colons in prose are followed by spaces, not by userinfo runs —
+    the narrow regex must not fire (the sync tests pin the same copy)."""
+    model_message = (
+        "The embedding model ('embed') is not available — check the model endpoint and retry."
+    )
+    assert sanitize_error(model_message) == model_message
+    sentence = "note: the sync failed: see the log for details"
+    assert sanitize_error(sentence) == sentence
+
+
+def test_email_in_prose_is_unchanged() -> None:
+    """``owner@example.com`` carries no colon userinfo run before the
+    ``@`` — the pattern does not match it, so it stays byte-identical
+    (pinned for determinism: the masker only rewrites ``user:pass@``)."""
+    message = "please contact owner@example.com about the failing push"
+    assert sanitize_error(message) == message
+
+
+def test_empty_string_is_unchanged() -> None:
+    assert sanitize_error("") == ""
+
+
+# --- Idempotence (masked forms) ---------------------------------------------
+
+
+def test_idempotent_on_masked_forms() -> None:
+    """Sanitizing an already-sanitized string is a no-op — the ``*****@``
+    replacement never forms a new ``user:pass@`` run in the pinned cases."""
+    for message in ("https://user:pass@host/repo.git", TWO_USERINFO, GIT_PUSH_FAILURE):
+        once = sanitize_error(message)
+        assert sanitize_error(once) == once
+
+
+# --- The sync alias refactor (phase 84, task 01) ----------------------------
+
+
+def test_sync_keeps_the_private_alias_of_the_shared_function() -> None:
+    """``app.api.sync._sanitize_error`` IS the shared sanitizer under the
+    private name — the phase-32 callers (``git_sources.py``, ``docs.py``)
+    import it through ``app.api.sync`` and see the identical function."""
+    assert sync_api._sanitize_error is sanitize_error
+    assert sync_api._sanitize_error(GIT_PUSH_FAILURE) == sanitize_error(GIT_PUSH_FAILURE)
diff --git a/tests/unit/test_llm_client.py b/tests/unit/test_llm_client.py
index c6378a2..9bc9126 100644
--- a/tests/unit/test_llm_client.py
+++ b/tests/unit/test_llm_client.py
@@ -189,6 +189,36 @@ def test_http_error_surfaces_status() -> None:
     assert llm.embed_batches == 0
 
 
+def test_embed_transport_failure_masks_credentials_in_base_url() -> None:
+    """Phase 84 (SEC-13): a base URL configured with embedded
+    ``user:pass@`` credentials never reaches the error message — the URL
+    in the raised :class:`EmbeddingError` is sanitized (``*****@``),
+    while the failure context stays readable."""
+    llm, _ = _make_client(
+        _FakeEmbeddingsService(fail=RuntimeError("connection refused")),
+        llm_base_url="https://svc:topsecret@llm.local/v1",
+    )
+    with pytest.raises(EmbeddingError) as exc:
+        asyncio.run(llm.embed(["hello"]))
+    msg = str(exc.value)
+    assert "https://*****@llm.local/v1" in msg
+    assert "topsecret" not in msg
+    assert "connection refused" in msg
+    assert llm.embed_batches == 0
+    # The credential-free pin stays byte-identical (sanitize is a no-op
+    # without userinfo): the default base URL appears verbatim.
+    llm_plain, _ = _make_client(
+        _FakeEmbeddingsService(fail=RuntimeError("connection refused"))
+    )
+    with pytest.raises(EmbeddingError) as exc_plain:
+        asyncio.run(llm_plain.embed(["hello"]))
+    assert (
+        str(exc_plain.value)
+        == "embeddings request to https://aipi.reeseapps.com/v1 failed: "
+        "connection refused"
+    )
+
+
 def test_missing_vector_row_is_rejected() -> None:
     llm, _ = _make_client(_FakeEmbeddingsService(drop_index=1))
     with pytest.raises(EmbeddingError, match="returned 1 vectors for 2 inputs"):
@@ -925,6 +955,22 @@ def test_chat_transport_failure_wrapped_as_llm_error_with_base_url() -> None:
     assert "aipi.reeseapps.com" in str(exc.value)
 
 
+def test_chat_transport_failure_masks_credentials_in_base_url() -> None:
+    """Phase 84 (SEC-13): the chat failure f-string sanitizes the base
+    URL the same way the embed path does (the five sites share the
+    construction; this is the chat representative)."""
+    llm, _ = _make_chat_client(
+        fail=RuntimeError("HTTP 502 Bad Gateway"),
+        llm_base_url="https://svc:topsecret@llm.local/v1",
+    )
+    with pytest.raises(LLMError) as exc:
+        asyncio.run(llm.chat([{"role": "user", "content": "q"}]))
+    msg = str(exc.value)
+    assert "https://*****@llm.local/v1" in msg
+    assert "topsecret" not in msg
+    assert "HTTP 502 Bad Gateway" in msg
+
+
 def test_chat_llm_error_passes_through_unwrapped() -> None:
     llm, _ = _make_chat_client(fail=LLMError("already wrapped"))
     with pytest.raises(LLMError, match="already wrapped"):