phase: 84_docs_push_error_sanitization

**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**

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