diff --git a/bin/install.js b/bin/install.js
index b7f11e4cf6..4d297d2a1e 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -563,9 +563,11 @@ function generateCodexAgentToml(agentName, agentContent) {
 
   const lines = [
     `sandbox_mode = "${sandboxMode}"`,
-    `developer_instructions = """`,
+    // Agent prompts contain raw backslashes in regexes and shell snippets.
+    // TOML literal multiline strings preserve them without escape parsing.
+    `developer_instructions = '''`,
     instructions,
-    `"""`,
+    `'''`,
   ];
   return lines.join('\n') + '\n';
 }
diff --git a/tests/codex-config.test.cjs b/tests/codex-config.test.cjs
index 758eedc845..58fe10e038 100644
--- a/tests/codex-config.test.cjs
+++ b/tests/codex-config.test.cjs
@@ -155,9 +155,9 @@ tools: Read, Grep, Glob
 
   test('includes developer_instructions from body', () => {
     const result = generateCodexAgentToml('gsd-executor', sampleAgent);
-    assert.ok(result.includes('developer_instructions = """'), 'has triple-quoted instructions');
+    assert.ok(result.includes("developer_instructions = '''"), 'has literal triple-quoted instructions');
     assert.ok(result.includes('<role>You are an executor.</role>'), 'body content in instructions');
-    assert.ok(result.includes('"""'), 'has closing triple quotes');
+    assert.ok(result.includes("'''"), 'has closing literal triple quotes');
   });
 
   test('defaults unknown agents to read-only', () => {