diff --git a/projects/gigabit-m1-frame-stiffness/README.md b/projects/gigabit-m1-frame-stiffness/README.md
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+# GigaBIT M1 — Reference Frame Stiffness Characterization
+
+**Client:** StarSpec
+**Project:** P04-GigaBIT-M1
+**Created:** 2026-03-04
+**Status:** Active — Model Setup
+
+---
+
+## Objective
+
+Determine minimum stiffness requirements for StarSpec's reference frame at 5 mirror support interface points. Quantify WFE sensitivity to frame compliance so StarSpec can design their frame to spec.
+
+## Approach
+
+**Hybrid B+D method** (war-room validated):
+
+1. **Method D (Sensitivity):** Prescribed unit displacements at each unique interface point, extract Zernike WFE sensitivity coefficients (nm/μm per DOF per point)
+2. **Method B (Stiffness Sweep):** CBUSH spring-to-ground at 5 interface points, sweep K to find knee points
+3. **Robustness:** One-soft-point, combined compliance, correlated displacement tests
+
+## Key Numbers
+
+| Metric | Value |
+|--------|-------|
+| Baseline WFE @ 40° | ~7.0 nm RMS (J5+ filtered) |
+| Baseline WFE @ 60° | ~13.0 nm RMS (J5+ filtered) |
+| ΔWFE budget (frame) | ≤ 1.0 nm RMS |
+| System allocation | ≤ 22 nm RMS (contract) |
+| Mechanical target | < 14 nm RMS |
+| Total runs | ~42 |
+
+## Interface Points (5 total)
+
+| Label | Type | Symmetry |
+|-------|------|----------|
+| V_top | Vertical support | Unique (on Y-Z symmetry axis) |
+| V_left | Vertical support | = V_right mirrored |
+| V_right | Vertical support | = V_left mirrored |
+| L_left | Lateral support | = L_right mirrored |
+| L_right | Lateral support | = L_left mirrored |
+
+**Unique points to test:** 3 (V_top, V_side, L_side)
+
+## Model
+
+- **Solver:** NX Nastran SOL 101 (linear static)
+- **Coordinate system:** Global (Z = optical axis)
+- **Zernike extractor:** Annular OPD, 50 modes, J5+ filtered RMS
+- **Reference subcase:** 20° elevation
+- **Test subcases:** 40° and 60° elevation
+- **Inner radius:** 135.75 mm (central hole)
+- **Outer radius:** 500.0 mm
+
+## Project Structure
+
+```
+gigabit-m1-frame-stiffness/
+├── README.md                   ← You are here
+├── models/                     # NX model files (drop .prt and .sim here)
+├── studies/
+│   ├── 01_sensitivity_method_d/  # Unit displacement sensitivity (9+3 runs)
+│   ├── 02_stiffness_sweep_method_b/  # K sweep campaigns (20 runs)
+│   └── 03_robustness/           # One-soft-point, combined, correlated (8 runs)
+├── deliverables/               # StarSpec requirement document (Rev A)
+├── kb/                         # Knowledge base notes
+└── images/                     # Plots, screenshots
+```
+
+## PKM Reference
+
+Full documentation: `obsidian-vault/2-Projects/P04-GigaBIT-M1/03-studies/Reference-Frame-Stiffness-Characterization/`
diff --git a/projects/gigabit-m1-frame-stiffness/studies/01_sensitivity_method_d/README.md b/projects/gigabit-m1-frame-stiffness/studies/01_sensitivity_method_d/README.md
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+# Study 01 — Sensitivity Map (Method D)
+
+**Type:** Parametric — Prescribed Unit Displacements
+**Runs:** 12 (9 unique @ 60° + 1 baseline + 2 spot checks @ 40°)
+**Model:** Enforced displacement BCs with expression control
+
+## What This Does
+
+Applies +1 μm displacement at each unique interface point in each global DOF direction, one at a time. Measures ΔWFE to build a sensitivity matrix: **nm WFE per μm displacement per DOF per point.**
+
+This is the PRIMARY deliverable for StarSpec.
+
+## .sim Setup Required
+
+1. Create 9 NX expressions: `dV1_X, dV1_Y, dV1_Z, dV2_X, dV2_Y, dV2_Z, dL1_X, dL1_Y, dL1_Z` (all default = 0)
+2. Apply enforced displacement BCs on all 5 support nodes referencing these expressions
+3. Symmetry ties: V_right X = −dV2_X, L_right X = −dL1_X; Y/Z same sign as left counterpart
+4. Gravity load at target elevation (60° or 40°)
+
+## Extractor
+
+Zernike annular OPD: 50 modes, J5+ filtered, inner_radius = 135.75 mm, reference subcase = 20° elevation.
+
+**Also extract individually:** J9, J10 (trefoil) and J11 (spherical) for secondary reporting.
+
+## Output
+
+Sensitivity matrix → feed into displacement limits and StarSpec deliverable.
diff --git a/projects/gigabit-m1-frame-stiffness/studies/01_sensitivity_method_d/atomizer_spec.json b/projects/gigabit-m1-frame-stiffness/studies/01_sensitivity_method_d/atomizer_spec.json
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+{
+  "meta": {
+    "version": "2.0",
+    "created": "2026-03-04T12:00:00Z",
+    "modified": "2026-03-04T12:00:00Z",
+    "created_by": "mario",
+    "modified_by": "mario",
+    "study_name": "01_sensitivity_method_d",
+    "description": "Method D — Unit displacement sensitivity map. Apply +1 μm prescribed displacement at each unique interface point (3 points × 3 DOF = 9 runs), extract Zernike WFE sensitivity coefficients. Uses symmetry: V_left≡V_right, L_left≡L_right.",
+    "tags": ["mirror", "zernike", "sensitivity", "frame-stiffness", "parametric"]
+  },
+  "model": {
+    "sim": {
+      "path": "ASSY_M1_assyfem1_sim1.sim",
+      "solver": "nastran",
+      "_note": "UPDATE: Set correct .sim filename after model drop"
+    },
+    "nx_settings": {
+      "nx_install_path": "C:\\Program Files\\Siemens\\NX2506",
+      "simulation_timeout_s": 600,
+      "_note": "UPDATE: Adjust NX path for your machine if different"
+    }
+  },
+  "design_variables": [
+    {
+      "id": "dv_001",
+      "name": "dV1_X",
+      "expression_name": "dV1_X",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_top displacement in global X (0 = fixed, 0.001 = +1 μm)"
+    },
+    {
+      "id": "dv_002",
+      "name": "dV1_Y",
+      "expression_name": "dV1_Y",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_top displacement in global Y"
+    },
+    {
+      "id": "dv_003",
+      "name": "dV1_Z",
+      "expression_name": "dV1_Z",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_top displacement in global Z (optical axis)"
+    },
+    {
+      "id": "dv_004",
+      "name": "dV2_X",
+      "expression_name": "dV2_X",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_side (left) displacement in global X"
+    },
+    {
+      "id": "dv_005",
+      "name": "dV2_Y",
+      "expression_name": "dV2_Y",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_side (left) displacement in global Y"
+    },
+    {
+      "id": "dv_006",
+      "name": "dV2_Z",
+      "expression_name": "dV2_Z",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "V_side (left) displacement in global Z"
+    },
+    {
+      "id": "dv_007",
+      "name": "dL1_X",
+      "expression_name": "dL1_X",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "L_side (left) displacement in global X"
+    },
+    {
+      "id": "dv_008",
+      "name": "dL1_Y",
+      "expression_name": "dL1_Y",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "L_side (left) displacement in global Y"
+    },
+    {
+      "id": "dv_009",
+      "name": "dL1_Z",
+      "expression_name": "dL1_Z",
+      "type": "continuous",
+      "bounds": {"min": 0.0, "max": 0.001},
+      "baseline": 0.0,
+      "units": "mm",
+      "enabled": true,
+      "description": "L_side (left) displacement in global Z"
+    }
+  ],
+  "extractors": [
+    {
+      "id": "ext_001",
+      "name": "Zernike Annular OPD — WFE Sensitivity",
+      "type": "zernike_opd",
+      "builtin": true,
+      "config": {
+        "inner_radius_mm": 135.75,
+        "outer_radius_mm": 500.0,
+        "n_modes": 50,
+        "filter_low_orders": 4,
+        "displacement_unit": "mm",
+        "reference_subcase": 2,
+        "_note": "J5+ filtered RMS. reference_subcase=2 is 20° elevation. Check subcase numbering in your model."
+      },
+      "outputs": [
+        {
+          "name": "rel_filtered_rms_40_vs_20",
+          "metric": "filtered_rms_nm"
+        },
+        {
+          "name": "rel_filtered_rms_60_vs_20",
+          "metric": "filtered_rms_nm"
+        }
+      ]
+    }
+  ],
+  "objectives": [
+    {
+      "id": "obj_001",
+      "name": "ΔWFE at 60° (primary — worst case)",
+      "direction": "minimize",
+      "weight": 1.0,
+      "source": {
+        "extractor_id": "ext_001",
+        "output_name": "rel_filtered_rms_60_vs_20"
+      },
+      "target": 1.0,
+      "units": "nm",
+      "_note": "This is a parametric study, not optimization. Objective is for tracking only."
+    }
+  ],
+  "constraints": [],
+  "optimization": {
+    "algorithm": {
+      "type": "GridSampler",
+      "config": {
+        "_note": "GridSampler for deterministic parametric sweep. Each run is a specific point in the design matrix."
+      }
+    },
+    "budget": {
+      "max_trials": 12
+    },
+    "_run_matrix_note": "Override with explicit trial list below. Each trial activates exactly ONE displacement expression = 0.001, rest = 0."
+  },
+  "run_matrix": {
+    "_description": "Explicit trial definitions for Method D. Each row is one FEA run. Atomizer sets these expression values before solving.",
+    "trials": [
+      {"trial": 0, "label": "baseline_all_fixed", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 1, "label": "V_top_Z",  "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0.001, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 2, "label": "V_top_X",  "dV1_X": 0.001, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 3, "label": "V_top_Y",  "dV1_X": 0, "dV1_Y": 0.001, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 4, "label": "V_side_Z", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0.001, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 5, "label": "V_side_X", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0.001, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 6, "label": "V_side_Y", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0.001, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 7, "label": "L_side_Z", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0.001, "elevation": "60"},
+      {"trial": 8, "label": "L_side_X", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0.001, "dL1_Y": 0, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 9, "label": "L_side_Y", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0.001, "dL1_Z": 0, "elevation": "60"},
+      {"trial": 10, "label": "spot_check_40_top1", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0.001, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "40", "_note": "Repeat top sensitive DOF at 40° — UPDATE label after ranking"},
+      {"trial": 11, "label": "spot_check_40_top2", "dV1_X": 0, "dV1_Y": 0, "dV1_Z": 0, "dV2_X": 0, "dV2_Y": 0, "dV2_Z": 0.001, "dL1_X": 0, "dL1_Y": 0, "dL1_Z": 0, "elevation": "40", "_note": "UPDATE after ranking"}
+    ]
+  }
+}
diff --git a/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/README.md b/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/README.md
new file mode 100644
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+++ b/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/README.md
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+# Study 02 — Stiffness Sweep (Method B)
+
+**Type:** Parametric — CBUSH Spring-to-Ground Sweep
+**Runs:** 22 (2 validation + 10 K_vert sweep + 10 K_lat sweep)
+**Model:** CBUSH elements at 5 interface points, offset ground nodes (−10mm Z)
+
+## What This Does
+
+Replaces fixed BCs with CBUSH springs. Sweeps translational stiffness from 1e4 → 1e10 N/m on log scale. Two independent campaigns:
+- Campaign 1: Sweep K_vert (laterals rigid)
+- Campaign 2: Sweep K_lat (verticals rigid)
+
+Finds the **knee point** where ΔWFE crosses the 1.0 nm budget.
+
+## .sim Setup Required
+
+1. Create 5 ground nodes (offset −10mm in −Z from each support node)
+2. SPC 123456 on all ground nodes
+3. Remove existing SPCs on 5 support nodes
+4. Create 5 CBUSH elements (support → ground, global coords)
+5. Create 2 PBUSH properties: 8001 (vertical, K=$K_vert) and 8002 (lateral, K=$K_lat)
+6. Create 2 NX expressions: `K_vert`, `K_lat` (default = 1e12)
+
+## Extractor
+
+Same as Study 01: Zernike annular OPD, 50 modes, J5+ filtered, annular aperture.
+
+## Output
+
+ΔWFE vs K curves → knee points → recommended minimum stiffness for StarSpec.
diff --git a/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/atomizer_spec.json b/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/atomizer_spec.json
new file mode 100644
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--- /dev/null
+++ b/projects/gigabit-m1-frame-stiffness/studies/02_stiffness_sweep_method_b/atomizer_spec.json
@@ -0,0 +1,126 @@
+{
+  "meta": {
+    "version": "2.0",
+    "created": "2026-03-04T12:00:00Z",
+    "modified": "2026-03-04T12:00:00Z",
+    "created_by": "mario",
+    "modified_by": "mario",
+    "study_name": "02_stiffness_sweep_method_b",
+    "description": "Method B — CBUSH spring-to-ground stiffness sweep. 5 CBUSH elements at interface points (offset 10mm in -Z). Sweep K_vertical (3 vertical CBUSHes) and K_lateral (2 lateral CBUSHes) independently to find knee points where ΔWFE exceeds 1.0 nm budget.",
+    "tags": ["mirror", "zernike", "stiffness", "frame-stiffness", "parametric", "cbush"]
+  },
+  "model": {
+    "sim": {
+      "path": "ASSY_M1_assyfem1_sim1.sim",
+      "solver": "nastran",
+      "_note": "UPDATE: This uses the CBUSH model variant (.sim with CBUSH elements + offset ground nodes). Different from Study 01."
+    },
+    "nx_settings": {
+      "nx_install_path": "C:\\Program Files\\Siemens\\NX2506",
+      "simulation_timeout_s": 600
+    }
+  },
+  "design_variables": [
+    {
+      "id": "dv_001",
+      "name": "K_vert",
+      "expression_name": "K_vert",
+      "type": "continuous",
+      "bounds": {"min": 1e4, "max": 1e12},
+      "baseline": 1e12,
+      "units": "N/m",
+      "enabled": true,
+      "description": "Translational stiffness for all 3 vertical support CBUSHes (K1=K2=K3=K_vert). Rotational K4=K5=K6 held at 1e12."
+    },
+    {
+      "id": "dv_002",
+      "name": "K_lat",
+      "expression_name": "K_lat",
+      "type": "continuous",
+      "bounds": {"min": 1e4, "max": 1e12},
+      "baseline": 1e12,
+      "units": "N/m",
+      "enabled": true,
+      "description": "Translational stiffness for all 2 lateral support CBUSHes (K1=K2=K3=K_lat). Rotational K4=K5=K6 held at 1e12."
+    }
+  ],
+  "extractors": [
+    {
+      "id": "ext_001",
+      "name": "Zernike Annular OPD — Stiffness Sweep",
+      "type": "zernike_opd",
+      "builtin": true,
+      "config": {
+        "inner_radius_mm": 135.75,
+        "outer_radius_mm": 500.0,
+        "n_modes": 50,
+        "filter_low_orders": 4,
+        "displacement_unit": "mm",
+        "reference_subcase": 2
+      },
+      "outputs": [
+        {
+          "name": "rel_filtered_rms_40_vs_20",
+          "metric": "filtered_rms_nm"
+        },
+        {
+          "name": "rel_filtered_rms_60_vs_20",
+          "metric": "filtered_rms_nm"
+        }
+      ]
+    }
+  ],
+  "objectives": [
+    {
+      "id": "obj_001",
+      "name": "ΔWFE at 60° — stiffness sweep tracking",
+      "direction": "minimize",
+      "weight": 1.0,
+      "source": {
+        "extractor_id": "ext_001",
+        "output_name": "rel_filtered_rms_60_vs_20"
+      },
+      "target": 1.0,
+      "units": "nm"
+    }
+  ],
+  "constraints": [],
+  "optimization": {
+    "algorithm": {
+      "type": "GridSampler",
+      "config": {}
+    },
+    "budget": {
+      "max_trials": 22
+    }
+  },
+  "run_matrix": {
+    "_description": "Campaign 1: Sweep K_vert (K_lat=1e12). Campaign 2: Sweep K_lat (K_vert=1e12). All at 60° elevation.",
+    "trials": [
+      {"trial": 0,  "label": "baseline_rigid",   "K_vert": 1e12,  "K_lat": 1e12, "elevation": "60", "_note": "Validation: should match fixed-BC baseline"},
+      {"trial": 1,  "label": "baseline_rigid_40", "K_vert": 1e12,  "K_lat": 1e12, "elevation": "40", "_note": "Validation at 40°"},
+
+      {"trial": 2,  "label": "Kv_1e4",  "K_vert": 1e4,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 3,  "label": "Kv_1e5",  "K_vert": 1e5,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 4,  "label": "Kv_3e5",  "K_vert": 3e5,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 5,  "label": "Kv_1e6",  "K_vert": 1e6,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 6,  "label": "Kv_3e6",  "K_vert": 3e6,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 7,  "label": "Kv_1e7",  "K_vert": 1e7,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 8,  "label": "Kv_3e7",  "K_vert": 3e7,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 9,  "label": "Kv_1e8",  "K_vert": 1e8,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 10, "label": "Kv_1e9",  "K_vert": 1e9,  "K_lat": 1e12, "elevation": "60"},
+      {"trial": 11, "label": "Kv_1e10", "K_vert": 1e10, "K_lat": 1e12, "elevation": "60"},
+
+      {"trial": 12, "label": "Kl_1e4",  "K_vert": 1e12, "K_lat": 1e4,  "elevation": "60"},
+      {"trial": 13, "label": "Kl_1e5",  "K_vert": 1e12, "K_lat": 1e5,  "elevation": "60"},
+      {"trial": 14, "label": "Kl_3e5",  "K_vert": 1e12, "K_lat": 3e5,  "elevation": "60"},
+      {"trial": 15, "label": "Kl_1e6",  "K_vert": 1e12, "K_lat": 1e6,  "elevation": "60"},
+      {"trial": 16, "label": "Kl_3e6",  "K_vert": 1e12, "K_lat": 3e6,  "elevation": "60"},
+      {"trial": 17, "label": "Kl_1e7",  "K_vert": 1e12, "K_lat": 1e7,  "elevation": "60"},
+      {"trial": 18, "label": "Kl_3e7",  "K_vert": 1e12, "K_lat": 3e7,  "elevation": "60"},
+      {"trial": 19, "label": "Kl_1e8",  "K_vert": 1e12, "K_lat": 1e8,  "elevation": "60"},
+      {"trial": 20, "label": "Kl_1e9",  "K_vert": 1e12, "K_lat": 1e9,  "elevation": "60"},
+      {"trial": 21, "label": "Kl_1e10", "K_vert": 1e12, "K_lat": 1e10, "elevation": "60"}
+    ]
+  }
+}
diff --git a/projects/gigabit-m1-frame-stiffness/studies/03_robustness/README.md b/projects/gigabit-m1-frame-stiffness/studies/03_robustness/README.md
new file mode 100644
index 00000000..583b05e9
--- /dev/null
+++ b/projects/gigabit-m1-frame-stiffness/studies/03_robustness/README.md
@@ -0,0 +1,26 @@
+# Study 03 — Robustness Checks
+
+**Type:** Parametric — Specific Scenarios
+**Runs:** 8
+**Model:** Uses both .sim setups (CBUSH for K tests, displacement for correlated tests)
+**Prerequisite:** Complete Studies 01 and 02 first (needs knee values)
+
+## What This Does
+
+Tests scenarios that the simple sweeps can't capture:
+
+1. **One-soft-point (3 runs):** What if one support is 10× softer than the rest?
+2. **Combined compliance (3 runs):** Both vertical and lateral at knee values simultaneously
+3. **Correlated displacement (2 runs):** All verticals move together (frame bending mode simulation)
+
+## Before Running
+
+Update `atomizer_spec.json` with actual knee values from Study 02:
+- Replace `KNEE` placeholders with K_vert_knee and K_lat_knee values
+- Replace `KNEE/10` with knee/10, `KNEE/2` with knee/2
+
+## Output
+
+- Interaction factor: is combined ΔWFE > sum of individual?
+- Worst-case single soft point identification
+- Correlated vs independent displacement comparison
diff --git a/projects/gigabit-m1-frame-stiffness/studies/03_robustness/atomizer_spec.json b/projects/gigabit-m1-frame-stiffness/studies/03_robustness/atomizer_spec.json
new file mode 100644
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--- /dev/null
+++ b/projects/gigabit-m1-frame-stiffness/studies/03_robustness/atomizer_spec.json
@@ -0,0 +1,123 @@
+{
+  "meta": {
+    "version": "2.0",
+    "created": "2026-03-04T12:00:00Z",
+    "modified": "2026-03-04T12:00:00Z",
+    "created_by": "mario",
+    "modified_by": "mario",
+    "study_name": "03_robustness",
+    "description": "Robustness checks: one-soft-point tests, combined compliance, and correlated displacement patterns. Run AFTER Studies 01 and 02 — uses knee values from Study 02.",
+    "tags": ["mirror", "zernike", "robustness", "frame-stiffness"]
+  },
+  "model": {
+    "sim": {
+      "path": "ASSY_M1_assyfem1_sim1.sim",
+      "solver": "nastran",
+      "_note": "Uses same CBUSH model variant as Study 02"
+    },
+    "nx_settings": {
+      "nx_install_path": "C:\\Program Files\\Siemens\\NX2506",
+      "simulation_timeout_s": 600
+    }
+  },
+  "design_variables": [
+    {
+      "id": "dv_001",
+      "name": "K_V_top",
+      "expression_name": "K_V_top",
+      "type": "continuous",
+      "bounds": {"min": 1e4, "max": 1e12},
+      "baseline": 1e12,
+      "units": "N/m",
+      "enabled": true,
+      "description": "Stiffness for V_top CBUSH only (for one-soft-point tests)"
+    },
+    {
+      "id": "dv_002",
+      "name": "K_V_side",
+      "expression_name": "K_V_side",
+      "type": "continuous",
+      "bounds": {"min": 1e4, "max": 1e12},
+      "baseline": 1e12,
+      "units": "N/m",
+      "enabled": true,
+      "description": "Stiffness for V_left + V_right CBUSHes (symmetric pair)"
+    },
+    {
+      "id": "dv_003",
+      "name": "K_L_side",
+      "expression_name": "K_L_side",
+      "type": "continuous",
+      "bounds": {"min": 1e4, "max": 1e12},
+      "baseline": 1e12,
+      "units": "N/m",
+      "enabled": true,
+      "description": "Stiffness for L_left + L_right CBUSHes (symmetric pair)"
+    }
+  ],
+  "extractors": [
+    {
+      "id": "ext_001",
+      "name": "Zernike Annular OPD — Robustness",
+      "type": "zernike_opd",
+      "builtin": true,
+      "config": {
+        "inner_radius_mm": 135.75,
+        "outer_radius_mm": 500.0,
+        "n_modes": 50,
+        "filter_low_orders": 4,
+        "displacement_unit": "mm",
+        "reference_subcase": 2
+      },
+      "outputs": [
+        {
+          "name": "rel_filtered_rms_40_vs_20",
+          "metric": "filtered_rms_nm"
+        },
+        {
+          "name": "rel_filtered_rms_60_vs_20",
+          "metric": "filtered_rms_nm"
+        }
+      ]
+    }
+  ],
+  "objectives": [
+    {
+      "id": "obj_001",
+      "name": "ΔWFE at 60° — robustness tracking",
+      "direction": "minimize",
+      "weight": 1.0,
+      "source": {
+        "extractor_id": "ext_001",
+        "output_name": "rel_filtered_rms_60_vs_20"
+      },
+      "target": 1.0,
+      "units": "nm"
+    }
+  ],
+  "constraints": [],
+  "optimization": {
+    "algorithm": {
+      "type": "GridSampler",
+      "config": {}
+    },
+    "budget": {
+      "max_trials": 8
+    }
+  },
+  "run_matrix": {
+    "_description": "UPDATE K_knee values after Study 02 completes. Replace 'KNEE' placeholders with actual values.",
+    "_K_vert_knee": "UPDATE_FROM_STUDY_02",
+    "_K_lat_knee": "UPDATE_FROM_STUDY_02",
+    "trials": [
+      {"trial": 0, "label": "one_soft_V_top",  "K_V_top": "KNEE/10", "K_V_side": 1e12,       "K_L_side": 1e12,       "elevation": "60", "_note": "V_top 10× below knee, rest rigid"},
+      {"trial": 1, "label": "one_soft_V_side",  "K_V_top": 1e12,      "K_V_side": "KNEE/10",  "K_L_side": 1e12,       "elevation": "60", "_note": "V_side 10× below knee, rest rigid"},
+      {"trial": 2, "label": "one_soft_L_side",  "K_V_top": 1e12,      "K_V_side": 1e12,       "K_L_side": "KNEE/10",  "elevation": "60", "_note": "L_side 10× below knee, rest rigid"},
+      {"trial": 3, "label": "combined_knee_60",  "K_V_top": "KNEE",   "K_V_side": "KNEE",     "K_L_side": "KNEE",     "elevation": "60", "_note": "All at knee values"},
+      {"trial": 4, "label": "combined_knee_40",  "K_V_top": "KNEE",   "K_V_side": "KNEE",     "K_L_side": "KNEE",     "elevation": "40", "_note": "All at knee @ 40°"},
+      {"trial": 5, "label": "combined_half_60",  "K_V_top": "KNEE/2", "K_V_side": "KNEE/2",   "K_L_side": "KNEE/2",   "elevation": "60", "_note": "All at half knee"},
+      {"trial": 6, "label": "corr_sag_all_V_down",   "_type": "method_d", "_note": "USE Study 01 setup: dV1_Z=dV2_Z=0.001 simultaneously (all 3 vertical +1μm Z). Tests correlated frame sag."},
+      {"trial": 7, "label": "corr_twist_V_split",    "_type": "method_d", "_note": "USE Study 01 setup: dV1_Z=+0.001, dV2_Z=-0.001 (V_top up, V_sides down). Tests frame twist."}
+    ]
+  }
+}