diff --git a/src/datamodel/node/data/Simulink.ValueType.md b/src/datamodel/node/data/Simulink.ValueType.md
index 1901c0b..5898846 100644
--- a/src/datamodel/node/data/Simulink.ValueType.md
+++ b/src/datamodel/node/data/Simulink.ValueType.md
@@ -6,8 +6,9 @@
 **MATLAB class:** `Simulink.ValueType`
 **Editable in our UI:** yes (Name, Description, Min, Max, Complexity, DimensionsMode)
 **Verified against:** MATLAB R2027a (probe_class('Simulink.ValueType'))
-**Partly unverified:** the Min / Max / Complexity / DimensionsMode unlock is verified
-in-process only. There is no MATLAB re-open gate for those four — see "Open questions".
+**Re-open gate:** RUN and PASSING as of 2026-09-16 — MATLAB opens a `.sldd` we wrote and
+reads Min / Max / Complexity / DimensionsMode back equal, in both formats. See
+"Open questions" for what that does and does not settle.
 
 ## Overview
 
@@ -142,11 +143,26 @@ produce a file MATLAB will not load.
 
 ## Open questions / deferred
 
-- **MATLAB re-open gate for the newly editable properties — NOT RUN.** Min, Max,
-  Complexity and DimensionsMode are verified in-process (serialize → re-parse) only. No
-  MATLAB was available where the unlock was made, so there is no PASS to record that
-  MATLAB loads the written file and reads the values back. Same status as the
-  `Simulink.BusElement` enum unlock, and worth running in the same pass.
+- **MATLAB re-open gate — RUN, PASS (2026-09-16, R2027a Prerelease 27.1.0.3393633).**
+  Min, Max, Complexity and DimensionsMode were verified end to end: this package wrote the
+  `.sldd`, MATLAB opened it, and MATLAB read every value back equal to what was set —
+  **in both formats**, text JSON and compressed-binary. Cases live in
+  `test/parity/matlab/writeback.live.test.ts` as `VALUE_TYPE_CASES`; run them with
+  `env DEX_MATLAB_CMD="<launcher> matlab" DEX_MATLAB_CWD="<sandbox>" npx vitest run
+  test/parity/matlab/writeback.live.test.ts`.
+
+  Two things the gate settles that no in-process test could:
+
+  - **`Min` is written as 0, not dropped.** The case deliberately uses a zero bound, the
+    value a truthiness gate loses. MATLAB reads back `0`, so the bound reaches the file as a
+    real number rather than an omitted key.
+  - **The enum casing is MATLAB's own.** `'complex'` lower-case and `'Variable'`
+    capitalised both load. This was the standing risk: MATLAB refuses the other spelling of
+    each, so a writer that normalised the case would have produced a file MATLAB cannot
+    open — a failure invisible to every test that reads back through our own parser.
+
+  The `Unit` property is not in the gate because it is not editable here (its schema
+  override is not `projected`); it is read-only and passes through untouched.
 
 - **Dimensions stays read-only**: a positive double vector with a symbolic-char
   alternative. Left a label for the reason `BusElementNode` records — the constraint has
diff --git a/test/busElementEnumEdit.test.ts b/test/busElementEnumEdit.test.ts
index 06097c0..9a49a4f 100644
--- a/test/busElementEnumEdit.test.ts
+++ b/test/busElementEnumEdit.test.ts
@@ -20,12 +20,14 @@
 //      taught to copy it across, an edit was stored, displayed, and then dropped on
 //      save — an unlock that changes nothing in the file.
 //
-// NOT covered here, and not covered anywhere yet: that MATLAB reopens the file and
-// reads these values back. That is the live tier
-// (test/parity/matlab/writeback.live.test.ts, which now carries a case per
-// property), it is gated on DEX_MATLAB_CMD, and it has never been run against this
-// change — there is no MATLAB on the machine it was written on. Everything below is
-// in-process only.
+// NOT covered here: that MATLAB reopens the file and reads these values back. That is
+// the live tier (test/parity/matlab/writeback.live.test.ts, which carries a case per
+// property), gated on DEX_MATLAB_CMD. It has now been RUN — 2026-09-16, R2027a
+// Prerelease, PASS for both properties in both .sldd formats. So the casing below is
+// no longer an assumption: MATLAB itself accepts 'complex' lower-case and 'Variable'
+// capitalised, and the `illegal` near-misses really are the values it refuses.
+// Everything in this file is still in-process, by design — it is the tier that runs
+// without MATLAB.
 
 import { describe, it, expect } from 'vitest';
 import { readFileSync } from 'node:fs';
diff --git a/test/parity/matlab/writeback.live.test.ts b/test/parity/matlab/writeback.live.test.ts
index 7bb359f..e431f24 100644
--- a/test/parity/matlab/writeback.live.test.ts
+++ b/test/parity/matlab/writeback.live.test.ts
@@ -16,11 +16,14 @@
 // 29/30/42), shape (defect 25 and Phase 6), element order (Phase 11), and the non-finites.
 //
 // The second array, ELEMENT_ENUM_CASES, covers the two bus-element enum properties item 13
-// made editable. Those cases have NEVER BEEN RUN: they were written on a machine with no
-// MATLAB, so their expectations state what the write is supposed to produce, not what MATLAB
-// was observed to produce. Whoever first runs this file with DEX_MATLAB_CMD set is the one
-// who finds out — and if MATLAB disagrees, the case is right and the writer is wrong until
-// proven otherwise.
+// made editable; the third, VALUE_TYPE_CASES, the Simulink.ValueType value properties.
+//
+// RUN AND PASSING as of 2026-09-16 — MATLAB R2027a Prerelease 27.1.0.3393633, all 32 cases
+// in this file, both .sldd formats. Until then the element-enum cases had never executed
+// (written on a machine with no MATLAB) and the ValueType cases did not exist, so their
+// expectations stated what the write was SUPPOSED to produce. They now state what MATLAB was
+// observed to produce. If a future run disagrees, the case is right and the writer is wrong
+// until proven otherwise.
 //
 // Skipped wholesale when DEX_MATLAB_CMD is unset, so CI and external contributors stay
 // green. Set it to the launcher plus its fixed args, e.g.
@@ -146,6 +149,44 @@ const ELEMENT_ENUM_CASES: Array<{ prop: string; field: string; set: string; why:
   },
 ];
 
+// The Simulink.ValueType value properties this project unlocked alongside the element enums.
+// Same reasoning as ELEMENT_ENUM_CASES, one fixture over: MyValueType in params.sldd, whose
+// bounds MATLAB left empty and whose enums it wrote as 'real' / 'Fixed'.
+//
+// Grouped two-per-case rather than one-per-property on purpose. Each `it` costs a MATLAB
+// launch, and verify_roundtrip.m already prints PASS/FAIL per KEY, so grouping halves the
+// wall clock without losing attribution: a Min that came back wrong names itself in the
+// output whether or not Max shared the launch.
+//
+// Min is 0, not a tidy 5. A zero bound is the value a `|| ''` fallback or a truthiness gate
+// silently drops, and it is indistinguishable from "no bound" everywhere except here — so if
+// the write path ever regresses to a truthy test, this is the case that fails.
+const VALUE_TYPE_CASES: Array<{
+  tag: string;
+  edits: Array<[string, string]>;
+  expect: Record<string, unknown>;
+  why: string;
+}> = [
+  {
+    tag: 'bounds',
+    edits: [
+      ['Min', '0'],
+      ['Max', '100'],
+    ],
+    expect: { Min: 0, Max: 100, __class__: 'Simulink.ValueType' },
+    why: 'the bounds that used to render blank in both panes — Min 0 is the falsy one',
+  },
+  {
+    tag: 'enums',
+    edits: [
+      ['complexity', 'complex'],
+      ['dimensionsMode', 'Variable'],
+    ],
+    expect: { Complexity: 'complex', DimensionsMode: 'Variable', __class__: 'Simulink.ValueType' },
+    why: "MATLAB's own non-uniform casing: 'complex' lower, 'Variable' capitalised",
+  },
+];
+
 // Each case launches MATLAB, so every `it` below needs an explicit timeout: vitest's
 // default is 5s and reports the whole tier as timeouts, which hides whatever MATLAB was
 // about to say. Measured over a full run of this file, 24 launches took 516s — ~21s each
@@ -153,7 +194,14 @@ const ELEMENT_ENUM_CASES: Array<{ prop: string; field: string; set: string; why:
 // start pays for the licence checkout and MATLAB's own startup on top of the work. Hence
 // 120s and not the 60s the other live suites use: they make one or two launches, this one
 // makes two dozen, and only its first is slow.
-const MATLAB_TIMEOUT = 120_000;
+//
+// Raised to 300s after measuring a second machine (2026-09-16), where MATLAB lives on a
+// NETWORK sandbox rather than a local install: the genuinely cold launch took 276s, and
+// warm launches settled at 33s. 120s would have failed the first test of the run and
+// reported it as a timeout, hiding whatever MATLAB was about to say — which is the exact
+// failure this constant already exists to avoid. The steady-state cost is unchanged; a
+// ceiling only matters when it is hit.
+const MATLAB_TIMEOUT = 300_000;
 
 // Both flavours: the two writers spell a typed value independently, which is how defect 30
 // survived the fix for defect 29.
@@ -223,5 +271,26 @@ for (const format of ['json', 'binary'] as const) {
         expect(out).toMatch(/RESULT PASS/);
       });
     });
+
+    VALUE_TYPE_CASES.forEach((c) => {
+      it(`MATLAB reads back our edits to MyValueType ${c.tag} — ${c.why}`, { timeout: MATLAB_TIMEOUT }, () => {
+        const uri = 'test://wb-vt-' + format + '-' + c.tag + '.sldd';
+        const model = loadModel(format, 'params.sldd', uri);
+        const node = entryByName(model, uri, 'MyValueType');
+        for (const [prop, value] of c.edits) {
+          expect(node.setProperty(prop, value), prop).toBe(true);
+        }
+        const bytes = serializeModel(model, format);
+        // In-process first, so a failure here is legibly ours and not MATLAB's. Read the node
+        // FIELDS rather than a pane, because the claim is about what reached the file.
+        const reparsed = reparseEntry(bytes, format, 'params.sldd', 'MyValueType');
+        for (const [key, want] of Object.entries(c.expect)) {
+          if (key.startsWith('__')) continue;
+          expect(reparsed[key], `${c.tag}/${key} in-process`).toBe(want);
+        }
+        const out = matlabAssertRoundTrip(bytes, 'MyValueType', c.expect);
+        expect(out).toMatch(/RESULT PASS/);
+      });
+    });
   });
 }