diff --git a/docs/soft-hash-channel-analysis.md b/docs/soft-hash-channel-analysis.md
index f7e14d0..51704ab 100644
--- a/docs/soft-hash-channel-analysis.md
+++ b/docs/soft-hash-channel-analysis.md
@@ -385,6 +385,23 @@ The reduction in §4 leaves three loose threads:
    spectrum of `W^T W` and compare to typical Hessian eigenvalue
    distributions on representative checkpoints.
 
+   **Phase 1a landed 2026-05-10** under #000034: synthetic-
+   ablation infrastructure at `bench/scripts/phi_alignment_probe.py`
+   (`measure_alignment(W, hessian_eval, *, k_top, k_bot, epsilon)
+   → AlignmentReport`; Lanczos top-k + bottom-k via
+   `scipy.sparse.linalg.eigsh`). 14 tests in
+   `tests/test_phi_alignment_probe.py` covering verdict
+   classification (`STRUCTURAL_ALIGNMENT`, `NO_ALIGNMENT`,
+   `ANTI_ALIGNED`), boundary cases, and KAT regression. KAT
+   fixture at `bench/fixtures/phi-alignment/synthetic-checkpoints.jsonl`
+   pins synthetic-checkpoint verdicts so the probe is regression-
+   guarded ahead of v7 deployment ramp-up. Lands under
+   `bench/scripts/` (measurement tool, not a substrate primitive
+   like `arborist/substrate/anchor_prg.py`). **Phase 1b** runs
+   the probe against a real v7 checkpoint when one becomes
+   available; the alignment-score distribution then resolves
+   this open question and feeds C_B1 tightening per #000043.
+
 2. **PRG modeling for `φ_PRG`.** The §4 reduction treats `φ_PRG`
    as a random oracle. In practice it's a deterministic PRG with
    public seed. The reduction holds modulo PRG security; we
@@ -441,8 +458,11 @@ The reduction in §4 leaves three loose threads:
 
 ## 11. Status
 
-**Open questions:** §9.1 (Hessian alignment under `φ_linear`,
-parks on v7 deployment per #000034 Phase 1b),
+**Open questions:** §9.1 (Hessian alignment under `φ_linear`:
+synthetic-ablation infrastructure landed 2026-05-10 per #000034
+Phase 1a — probe + 14 tests + KAT fixture; parks on v7
+deployment data per #000034 Phase 1b for the actual checkpoint
+measurement),
 §9.2 (PRG cryptographic strength for `φ_PRG`: decision pinned +
 Phase 1 reference implementation landed 2026-05-10 per #000035 —
 HMAC-SHA-512 with 32-byte committed seed, KAT-pinned; awaits v7