diff --git a/packages/server/scripts/supervisor.logging.test.ts b/packages/server/scripts/supervisor.logging.test.ts
index 7589cb92a1..6f9754994a 100644
--- a/packages/server/scripts/supervisor.logging.test.ts
+++ b/packages/server/scripts/supervisor.logging.test.ts
@@ -29,6 +29,7 @@ async function runSupervisorFixture(options: {
   blockLogPath?: boolean;
   /** Close the reading end of the supervisor's stdout and stderr as soon as it starts. */
   closeOutput?: boolean;
+  env?: NodeJS.ProcessEnv;
 }): Promise<{
   code: number | null;
   signal: NodeJS.Signals | null;
@@ -84,7 +85,9 @@ async function runSupervisorFixture(options: {
         ];
   const child = spawn(command, args, {
     cwd: repoRoot,
-    env: { ...process.env },
+    // A Node color-conflict warning can hit closed stderr before runSupervisor installs
+    // its pipe-error handlers. This fixture exercises the supervisor's own output.
+    env: { ...process.env, ...options.env, NO_COLOR: undefined, FORCE_COLOR: undefined },
     stdio: ["ignore", "pipe", "pipe"],
   });
 
@@ -205,10 +208,16 @@ describe("supervisor durable logging", () => {
     expect(result.stderr).toContain('"worker-json-stderr"');
   });
 
-  test("keeps supervising the worker when nobody reads its stdout or stderr", async () => {
-    const result = await runSupervisorFixture({
-      closeOutput: true,
-      workerSource: `
+  test.each([
+    { colors: "inherited", env: {} },
+    { colors: "conflicting", env: { NO_COLOR: "1", FORCE_COLOR: "1" } },
+  ])(
+    "keeps supervising the worker when nobody reads its stdout or stderr with $colors colors",
+    async ({ env }) => {
+      const result = await runSupervisorFixture({
+        closeOutput: true,
+        env,
+        workerSource: `
         process.on("message", (message) => {
           if (message?.type === "paseo:graceful-shutdown") process.exit(0);
         });
@@ -220,14 +229,15 @@ describe("supervisor durable logging", () => {
         }, 500);
         setInterval(() => {}, 1000);
       `,
-    });
+      });
 
-    expect(result.code).toBe(0);
-    expect(result.signal).toBeNull();
-    expect(result.log).toContain("first stderr line\n");
-    expect(result.log).toContain("later stdout line\n");
-    expect(result.log).toContain('"reason":"closed_output_probe"');
-  });
+      expect(result.code).toBe(0);
+      expect(result.signal).toBeNull();
+      expect(result.log).toContain("first stderr line\n");
+      expect(result.log).toContain("later stdout line\n");
+      expect(result.log).toContain('"reason":"closed_output_probe"');
+    },
+  );
 
   test("preserves raw non-JSON stdout and stderr lines", async () => {
     const result = await runSupervisorFixture({
diff --git a/packages/server/src/utils/spawn.launch-regression.test.ts b/packages/server/src/utils/spawn.launch-regression.test.ts
index 847214c624..4943e68990 100644
--- a/packages/server/src/utils/spawn.launch-regression.test.ts
+++ b/packages/server/src/utils/spawn.launch-regression.test.ts
@@ -126,10 +126,15 @@ async function runFixture(params: {
   command: string;
   args: string[];
   shell?: boolean;
+  env?: NodeJS.ProcessEnv;
 }): Promise<SpawnResult> {
   const child = spawnProcess(params.command, params.args, {
     env: {
       ...process.env,
+      ...params.env,
+      // Terminal color settings must not add Node warnings to the argv fixture's stderr.
+      NO_COLOR: undefined,
+      FORCE_COLOR: undefined,
       PASEO_EXPECTED_ARGV_JSON: JSON.stringify(["--config", JSON_ARG]),
     },
     stdio: ["ignore", "pipe", "pipe"],
@@ -216,6 +221,8 @@ async function findAndLaunch(fixture: LaunchFixture): Promise<{
     const child = spawnProcess(found, fixture.args, {
       env: {
         ...process.env,
+        NO_COLOR: undefined,
+        FORCE_COLOR: undefined,
         PASEO_EXPECTED_ARGV_JSON: fixture.expectedArgvJson,
         PASEO_ARGV_SLICE_FROM: String(fixture.sliceFrom),
       },
@@ -331,18 +338,25 @@ describe.runIf(isPlatform("win32"))("Windows spawn launch regression", () => {
 });
 
 describe.skipIf(isPlatform("win32"))("spawn launch regression smoke", () => {
-  test("direct launch with a space-containing executable works on this platform", async () => {
-    const fixture = makeFixture();
+  test.each([
+    { colors: "inherited", env: {} },
+    { colors: "conflicting", env: { NO_COLOR: "1", FORCE_COLOR: "1" } },
+  ])(
+    "direct launch with a space-containing executable works with $colors colors",
+    async ({ env }) => {
+      const fixture = makeFixture();
 
-    const result = await runFixture({
-      command: fixture.fakeDaemonNode,
-      args: [fixture.assertScript, ...fixture.expectedArgs],
-      shell: false,
-    });
+      const result = await runFixture({
+        command: fixture.fakeDaemonNode,
+        args: [fixture.assertScript, ...fixture.expectedArgs],
+        shell: false,
+        env,
+      });
 
-    expect(result.error).toBeNull();
-    expect(result.code).toBe(0);
-    expect(result.stderr).toBe("");
-    expect(result.stdout.trim()).toBe("ARGV_OK");
-  });
+      expect(result.error).toBeNull();
+      expect(result.code).toBe(0);
+      expect(result.stderr).toBe("");
+      expect(result.stdout.trim()).toBe("ARGV_OK");
+    },
+  );
 });