diff --git a/harness/pstack/claude-code/skills/statechart/scripts/test/statechart.test.mjs b/harness/pstack/claude-code/skills/statechart/scripts/test/statechart.test.mjs
index 543fe8d67..bb6fe329e 100644
--- a/harness/pstack/claude-code/skills/statechart/scripts/test/statechart.test.mjs
+++ b/harness/pstack/claude-code/skills/statechart/scripts/test/statechart.test.mjs
@@ -8,6 +8,7 @@ import {
   mkdtempSync,
   readdirSync,
   readFileSync,
+  realpathSync,
   renameSync,
   rmSync,
   statSync,
@@ -15,7 +16,7 @@ import {
   utimesSync,
   writeFileSync,
 } from "node:fs";
-import { tmpdir } from "node:os";
+import { tmpdir as osTmpdir } from "node:os";
 import { basename, delimiter, dirname, join, posix, win32 } from "node:path";
 import { test } from "node:test";
 import { setTimeout as sleep } from "node:timers/promises";
@@ -47,6 +48,7 @@ import { ruleBook } from "../rule-book.mjs";
 import { copyPath } from "../snapshot.mjs";
 import { findTlc, JAVA_TOOL, TLC_TOOL } from "../tlc-tools.mjs";
 
+const tmpdir = () => realpathSync(osTmpdir());
 const here = dirname(fileURLToPath(import.meta.url));
 const scripts = dirname(here);
 const fixture = (name) => readFileSync(join(here, name), "utf8");
@@ -6160,6 +6162,7 @@ int rename(const char *from, const char *to) {
 }
 `;
 const failingRenames = (() => {
+  if (process.platform !== "linux") return null;
   const dir = mkdtempSync(join(tmpdir(), "statechart-preload-"));
   writeFileSync(join(dir, "rename.c"), failRenames);
   const so = join(dir, "rename.so");
@@ -6168,7 +6171,7 @@ const failingRenames = (() => {
 })();
 test(
   "a run whose rename fails after it moves the output folder aside puts the folder back, or says where it is",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6204,7 +6207,7 @@ test(
 
 test(
   "a run on a filesystem that cannot rename copies its files into place",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6231,7 +6234,7 @@ test(
 
 test(
   "a run that cannot rename replaces a folder that another run makes before its copy, and keeps one that another run makes during its copy",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6263,7 +6266,7 @@ test(
 
 test(
   "a run that cannot rename stops when another run removes its folder during its copy and makes an empty one in its place, and keeps that folder",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6284,7 +6287,7 @@ test(
 
 test(
   "a run that cannot rename keeps the folder that another run puts in place of its folder as soon as the run makes it",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
diff --git a/pstack/skills/statechart/scripts/test/statechart.test.mjs b/pstack/skills/statechart/scripts/test/statechart.test.mjs
index 543fe8d67..bb6fe329e 100644
--- a/pstack/skills/statechart/scripts/test/statechart.test.mjs
+++ b/pstack/skills/statechart/scripts/test/statechart.test.mjs
@@ -8,6 +8,7 @@ import {
   mkdtempSync,
   readdirSync,
   readFileSync,
+  realpathSync,
   renameSync,
   rmSync,
   statSync,
@@ -15,7 +16,7 @@ import {
   utimesSync,
   writeFileSync,
 } from "node:fs";
-import { tmpdir } from "node:os";
+import { tmpdir as osTmpdir } from "node:os";
 import { basename, delimiter, dirname, join, posix, win32 } from "node:path";
 import { test } from "node:test";
 import { setTimeout as sleep } from "node:timers/promises";
@@ -47,6 +48,7 @@ import { ruleBook } from "../rule-book.mjs";
 import { copyPath } from "../snapshot.mjs";
 import { findTlc, JAVA_TOOL, TLC_TOOL } from "../tlc-tools.mjs";
 
+const tmpdir = () => realpathSync(osTmpdir());
 const here = dirname(fileURLToPath(import.meta.url));
 const scripts = dirname(here);
 const fixture = (name) => readFileSync(join(here, name), "utf8");
@@ -6160,6 +6162,7 @@ int rename(const char *from, const char *to) {
 }
 `;
 const failingRenames = (() => {
+  if (process.platform !== "linux") return null;
   const dir = mkdtempSync(join(tmpdir(), "statechart-preload-"));
   writeFileSync(join(dir, "rename.c"), failRenames);
   const so = join(dir, "rename.so");
@@ -6168,7 +6171,7 @@ const failingRenames = (() => {
 })();
 test(
   "a run whose rename fails after it moves the output folder aside puts the folder back, or says where it is",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6204,7 +6207,7 @@ test(
 
 test(
   "a run on a filesystem that cannot rename copies its files into place",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6231,7 +6234,7 @@ test(
 
 test(
   "a run that cannot rename replaces a folder that another run makes before its copy, and keeps one that another run makes during its copy",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6263,7 +6266,7 @@ test(
 
 test(
   "a run that cannot rename stops when another run removes its folder during its copy and makes an empty one in its place, and keeps that folder",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);
@@ -6284,7 +6287,7 @@ test(
 
 test(
   "a run that cannot rename keeps the folder that another run puts in place of its folder as soon as the run makes it",
-  { skip: needsTlc.skip || (!failingRenames && "cannot compile a rename preload") },
+  { skip: needsTlc.skip || (!failingRenames && "needs LD_PRELOAD on Linux, or cannot compile a rename preload") },
   () => {
     const dir = mkdtempSync(join(tmpdir(), "statechart-"));
     writeLamp(dir);