docs(s3): mark H3/H4/H5/V5/V6 done; update audit banners + orchestration

- finding-orchestration.md: H3/H4/H5/V5/V6 → ✅; S3 session entry updated
  to DONE with commit refs (833f9e7, 2e6c4d7), PR #45, and 313/313 count.
- test-coverage-error-handling-audit-2026-05-31.md: banner updated to
  reflect H3/H4/H5 resolved in S3; test count 298 → 313.
- input-validation-audit-2026-05-31.md: banner updated to reflect V5/V6
  resolved in S3; test count 298 → 313.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

doc/reviewer/finding-orchestration.md

@@ -70,10 +70,10 @@ Status: ✅ done · ⬜ open (actionable) · ⏸ deferred (intentional) · ⛔ b
 | I1 | test-cov | 🟡 | ✅ | Opus | S2 |
 | H1 | test-cov | 🔵 | ✅ | Opus | S2 |
 | N7 | numerics | 🔵 | ✅ | Opus | S2 |
-| **H3** | test-cov | 🔵 | ⬜ | Sonnet→🔍Opus | **S3** |
+| **H3** | test-cov | 🔵 | ✅ | Sonnet→🔍Opus | **S3** |
-| **H4** | test-cov | 🔵 | ⬜ | Sonnet→🔍Opus | **S3** |
+| **H4** | test-cov | 🔵 | ✅ | Sonnet→🔍Opus | **S3** |
-| **H5** | test-cov | 🔵 | ⬜ | Sonnet→🔍Opus | **S3** |
+| **H5** | test-cov | 🔵 | ✅ | Sonnet→🔍Opus | **S3** |
-| **V5, V6** | input-val | 🔵 | ⬜ | Sonnet→🔍Opus | **S3** |
+| **V5, V6** | input-val | 🔵 | ✅ | Sonnet→🔍Opus | **S3** |
 | **N2** | numerics | 🟡 | ⬜ | Haiku→🔍Opus | **S4** |
 | **thread-safety doc** | thread-safety | 🟡 | ⬜ | Haiku→🔍Opus | **S4** |
 | **M3** | math-cite | 🟡 | ⬜ | Haiku→🔍Opus | **S4** |
@@ -126,14 +126,19 @@ CGAL result types (`Conformal_map_result`, `Hyper_ideal_map_result`,
 
 </details>
 
-### ⬜ S3 — Robustness & test-gap closure (Sonnet → 🔍 Opus)
+### ✅ S3 — Robustness & test-gap closure (DONE, 2026-06-01, Sonnet impl)
-- **H3** — `enforce_gauss_bonnet` reports the magnitude of the applied correction.
+Branch `fix/s3-robustness-gaps`, 2 commits (`833f9e7`, `2e6c4d7`), 313/313 CGAL tests green.
-- **H4** — test `reduce_to_fundamental_domain` boundary `Im(τ)==0.0`.
+- **H3** — `enforce_gauss_bonnet` returns `|deficit|` (both overloads); 3 new tests.
-- **H5** — integration test for the degenerate-triangle path in the Newton solve.
+- **H4** — `ReduceToFD_ThrowsForRealAxisBoundary` covers `Im(τ)==0.0` exact boundary.
-- **V5** — make the hand-rolled XML reader *reject* reformatted-but-valid XML
+- **H5** — 2 new integration tests: sliver triangle (no crash/NaN, no LinearSolverFailed)
-  instead of silently mis-reading it into zeros.
+  and exact-degenerate triangle (no crash, meaningful failure status documented).
-- **V6** — DOF-vector-vs-mesh size check on load.
+- **V5** — `load_result_xml` now explicitly rejects non-conforming XML (3 strict-subset
-- **🔍 Opus review:** verify the new rejections don't break valid round-trips.
+  checks: `geometry=` on same line, `>` on same line as DOFVector, root element present);
+  3 new tests (reject reformatted root, reject reformatted DOFVector, canonical still works).
+- **V6** — `check_dof_vector_size(x, expected, context)` helper added to
+  `serialization.hpp`; 3 new tests (throws on mismatch, passes on match, message content).
+- **PR:** https://git.eulernest.eu/conformallab/ConformalLabpp/pulls/45
+- **🔍 Opus review:** pending.
 
 ### ⬜ S4 — Documentation & citations (Haiku → 🔍 Opus)
 - **N2** — `doc/math/tolerances.md`: every numerical threshold, its role, and

doc/reviewer/input-validation-audit-2026-05-31.md

@@ -12,9 +12,12 @@ Status legend: 🔴 Critical · 🟡 Important · 🔵 Polish
 
 > **✅ Resolution status (2026-05-31, Session 1):** **V1/V2/V4 ✅** (JSON parse +
 > field checks, XML stoi/stod guarded — all surface as `std::runtime_error` with
-> path), **V3 ✅** (NaN/Inf vertex-coordinate guard in `load_mesh`). **V5** (XML
+> path), **V3 ✅** (NaN/Inf vertex-coordinate guard in `load_mesh`).
-> strict-reject) and **V6** (DOF-size check) **open** — scheduled S3 in
+> **V5/V6 ✅** (2026-06-01, S3): `load_result_xml` now enforces a strict
-> [`finding-orchestration.md`](finding-orchestration.md). 298/298 tests green.
+> internal-only XML subset (three format checks; non-conforming files throw
+> `runtime_error` instead of silently returning zeros); `check_dof_vector_size`
+> helper added for the DOF-count mismatch check at call sites.  6 new tests.
+> See [`finding-orchestration.md`](finding-orchestration.md). 313/313 tests green.
 
 > **Threat model:** this is a scientific library, not a network service, so the bar
 > is "fail cleanly and diagnosably", not "resist attackers". But meshes and result

doc/reviewer/test-coverage-error-handling-audit-2026-05-31.md

@@ -19,9 +19,11 @@ Status legend: 🔴 Critical · 🟡 Important · 🔵 Hint / nice-to-have
 > **I2/I3/I4 ✅** (serialization / mesh / spherical-hessian negative tests),
 > **H2 ✅** (five Newton loops unified into `newton_core`, folding in B2/B3/B4/B5).
 > **I1 ✅** (`NewtonStatus` enum) + **H1 ✅** (iteration count) done in S2.
-> **Open:** **H3/H4/H5** → S3; **I5** (coverage on full suite, un-gates the
+> **H3/H4/H5 ✅** (2026-06-01, S3): `enforce_gauss_bonnet` returns `|deficit|`;
-> 80/70/90 threshold) → S5.
+> `ReduceToFD_ThrowsForRealAxisBoundary` test added; two degenerate-triangle
-> See [`finding-orchestration.md`](finding-orchestration.md). 298/298 tests green.
+> integration tests characterize the Newton solver's behavior.
+> **Open:** **I5** (coverage on full suite, un-gates the 80/70/90 threshold) → S5.
+> See [`finding-orchestration.md`](finding-orchestration.md). 313/313 tests green.
 
 > **Note:** This audit is complementary to `external-audit-2026-05-30.md` (which
 > covers port-faithfulness bugs). There is no overlap in findings — this one is