diff --git a/docs/design/iter-slm256-lot2-03-not-authorized-20260725.json b/docs/design/iter-slm256-lot2-03-not-authorized-20260725.json
new file mode 100644
index 000000000..f371b30c2
--- /dev/null
+++ b/docs/design/iter-slm256-lot2-03-not-authorized-20260725.json
@@ -0,0 +1,26 @@
+{
+  "contract_hash": "238793d40b979f3667ddc5ab5a56877681c8d3201116834310704238218fa866",
+  "contract_id": "latent-workspace-capacity-gate-v1",
+  "issue": {
+    "activation_requirement": "SLM-249 provides data-derived stage count/length distributions and accepted stage order; SLM-251 provides a qualified faithful treatment and continued explicit control; SLM-252 provides the selected supervision routing/timing/grounding contract.",
+    "alias": "LOT2-03",
+    "gate_contract_id": "latent-workspace-capacity-gate-v1",
+    "linear_issue": "SLM-256",
+    "slug": "lot2-03-workspace-capacity",
+    "title": "Sweep Kxc latent capacity, semantic block order, and output-length independence"
+  },
+  "lot1_01_disposition": "not_authorized",
+  "lot1_02_disposition": "not_authorized",
+  "schema_version": "lot_downstream_gate/v1",
+  "verdict": "not_authorized",
+  "verdict_rationale": "LOT2-03 (SLM-256) activation requires: SLM-249 provides data-derived stage count/length distributions and accepted stage order; SLM-251 provides a qualified faithful treatment and continued explicit control; SLM-252 provides the selected supervision routing/timing/grounding contract. The LOT1-02 launch gate reports 'not_authorized' (LOT1-01 disposition 'not_authorized'): no faithful K x c model path, curriculum, Stage 0 parent, or continued-explicit control exists, and SLM-249's oracle ceiling is not positive. Closing not_authorized in plan-only/bounded-diagnostic mode; no training, factorial, intervention, or systems code is added by this disposition.",
+  "version_stamp": {
+    "code_commit": "9d6c9101adf1ed435fbcbcf97b8be7d01a8b6e9c",
+    "code_dirty": true,
+    "components": {
+      "harness.experiments": "v115"
+    },
+    "stamp_schema": "version_stamp/v1",
+    "stamped_at": "2026-07-25T16:17:17.886609+00:00"
+  }
+}
diff --git a/docs/design/iter-slm256-lot2-03-not-authorized-20260725.md b/docs/design/iter-slm256-lot2-03-not-authorized-20260725.md
new file mode 100644
index 000000000..1b26b2af3
--- /dev/null
+++ b/docs/design/iter-slm256-lot2-03-not-authorized-20260725.md
@@ -0,0 +1,15 @@
+# SLM-256 LOT2-03 — Downstream-gate disposition (latent-workspace-capacity-gate-v1)
+
+Verdict: **not_authorized**
+
+LOT2-03 (SLM-256) activation requires: SLM-249 provides data-derived stage count/length distributions and accepted stage order; SLM-251 provides a qualified faithful treatment and continued explicit control; SLM-252 provides the selected supervision routing/timing/grounding contract. The LOT1-02 launch gate reports 'not_authorized' (LOT1-01 disposition 'not_authorized'): no faithful K x c model path, curriculum, Stage 0 parent, or continued-explicit control exists, and SLM-249's oracle ceiling is not positive. Closing not_authorized in plan-only/bounded-diagnostic mode; no training, factorial, intervention, or systems code is added by this disposition.
+
+## Upstream chain
+
+- LOT1-02 launch gate (SLM-251): `not_authorized`
+- LOT1-01 activation gate (SLM-250): `not_authorized`
+- Activation requirement: SLM-249 provides data-derived stage count/length distributions and accepted stage order; SLM-251 provides a qualified faithful treatment and continued explicit control; SLM-252 provides the selected supervision routing/timing/grounding contract.
+
+## Non-goals honored
+
+No training campaign, factorial, readout/decoder, intervention, systems measurement, or production default change. This disposition is itself the deliverable while the upstream activation gate is unmet.
diff --git a/src/slm_training/harnesses/experiments/lot_downstream_gate.py b/src/slm_training/harnesses/experiments/lot_downstream_gate.py
index 528681a60..fdd7edfd8 100644
--- a/src/slm_training/harnesses/experiments/lot_downstream_gate.py
+++ b/src/slm_training/harnesses/experiments/lot_downstream_gate.py
@@ -121,6 +121,19 @@ def to_dict(self) -> dict[str, Any]:
             "diagnostic."
         ),
     ),
+    "SLM-256": DownstreamIssueSpec(
+        linear_issue="SLM-256",
+        alias="LOT2-03",
+        title="Sweep Kxc latent capacity, semantic block order, and output-length independence",
+        gate_contract_id="latent-workspace-capacity-gate-v1",
+        slug="lot2-03-workspace-capacity",
+        activation_requirement=(
+            "SLM-249 provides data-derived stage count/length distributions "
+            "and accepted stage order; SLM-251 provides a qualified faithful "
+            "treatment and continued explicit control; SLM-252 provides the "
+            "selected supervision routing/timing/grounding contract."
+        ),
+    ),
 }
 
 
diff --git a/src/slm_training/resources/versions.json b/src/slm_training/resources/versions.json
index c76d1494b..2c145ed8d 100644
--- a/src/slm_training/resources/versions.json
+++ b/src/slm_training/resources/versions.json
@@ -1912,7 +1912,7 @@
       ]
     },
     "harness.experiments": {
-      "version": "v121",
+      "version": "v122",
       "kind": "harness",
       "paths": [
         "scripts/run_slm298_capacity_context_curriculum.py",
@@ -1921,6 +1921,11 @@
         "tests/test_scripts/test_run_slm298_capacity_context_curriculum.py"
       ],
       "history": [
+        {
+          "version": "v122",
+          "date": "2026-07-25",
+          "note": "register SLM-256 LOT2-03 in the LOT downstream gate registry; closes not_authorized off the unmet LOT1/LOT2 chain"
+        },
         {
           "version": "v121",
           "date": "2026-07-25",
@@ -1996,6 +2001,11 @@
           "date": "2026-07-25",
           "note": "add SLM-300 AP-015 self-context exposure-bias curriculum manifest, policy-origin-mixture wiring/fixture harness, and mixture-zero legacy-equivalence invariant"
         },
+        {
+          "version": "v115",
+          "date": "2026-07-25",
+          "note": "register SLM-256 LOT2-03 in the LOT downstream gate registry; closes not_authorized off the unmet LOT1/LOT2 chain"
+        },
         {
           "version": "v114",
           "date": "2026-07-25",
@@ -9826,7 +9836,7 @@
       ]
     },
     "harness.experiments.lot_downstream_gate": {
-      "version": "v4",
+      "version": "v5",
       "kind": "gate",
       "paths": [
         "docs/design/iter-slm252-lot2-01-not-authorized-20260725.json",
@@ -9837,6 +9847,8 @@
         "docs/design/iter-slm254-lot3-01-not-authorized-20260725.md",
         "docs/design/iter-slm255-lot3-02-not-authorized-20260725.json",
         "docs/design/iter-slm255-lot3-02-not-authorized-20260725.md",
+        "docs/design/iter-slm256-lot2-03-not-authorized-20260725.json",
+        "docs/design/iter-slm256-lot2-03-not-authorized-20260725.md",
         "scripts/evaluate_lot_downstream_gate.py",
         "src/slm_training/harnesses/experiments/lot_downstream_gate.py",
         "tests/test_harnesses/experiments/test_lot_downstream_gate.py",
@@ -9844,9 +9856,14 @@
       ],
       "history": [
         {
-          "version": "v4",
+          "version": "v5",
           "date": "2026-07-25",
-          "note": "add SLM-255 LOT3-02 registry entry + not_authorized iter docs (alternative-valid-latent-gate-v1)"
+          "note": "add SLM-256 LOT2-03 registry entry + not_authorized iter docs (latent-workspace-capacity-gate-v1)"
+        },
+        {
+          "version": "v5",
+          "date": "2026-07-25",
+          "note": "add SLM-256 LOT2-03 registry entry + not_authorized iter docs (latent-workspace-capacity-gate-v1)"
         },
         {
           "version": "v4",
diff --git a/tests/test_harnesses/experiments/test_lot_downstream_gate.py b/tests/test_harnesses/experiments/test_lot_downstream_gate.py
index 3a6474795..4336ebc8b 100644
--- a/tests/test_harnesses/experiments/test_lot_downstream_gate.py
+++ b/tests/test_harnesses/experiments/test_lot_downstream_gate.py
@@ -132,3 +132,11 @@ def test_slm255_real_contracts_are_not_authorized() -> None:
 
     assert contract.verdict == NOT_AUTHORIZED
     assert contract.contract_id == "alternative-valid-latent-gate-v1"
+
+
+def test_slm256_real_contracts_are_not_authorized() -> None:
+    fidelity, trace = _real_contracts()
+    contract = evaluate_downstream_gate(DOWNSTREAM_ISSUES["SLM-256"], fidelity, trace)
+
+    assert contract.verdict == NOT_AUTHORIZED
+    assert contract.contract_id == "latent-workspace-capacity-gate-v1"
diff --git a/tests/test_scripts/test_evaluate_lot_downstream_gate.py b/tests/test_scripts/test_evaluate_lot_downstream_gate.py
index 7833c5ef9..c218b4fc5 100644
--- a/tests/test_scripts/test_evaluate_lot_downstream_gate.py
+++ b/tests/test_scripts/test_evaluate_lot_downstream_gate.py
@@ -64,3 +64,12 @@ def test_slm255_run_reports_not_authorized(tmp_path: Path) -> None:
     data = json.loads((out / "lot3_02_alternative_valid_latents_gate.json").read_text())
     assert data["verdict"] == "not_authorized"
     assert data["issue"]["alias"] == "LOT3-02"
+
+
+def test_slm256_run_reports_not_authorized(tmp_path: Path) -> None:
+    out = tmp_path / "gate256"
+    rc = evaluate_lot_downstream_gate.main(["--issue", "SLM-256", "--out", str(out)])
+    assert rc == 0
+    data = json.loads((out / "lot2_03_workspace_capacity_gate.json").read_text())
+    assert data["verdict"] == "not_authorized"
+    assert data["issue"]["alias"] == "LOT2-03"