From afa48c64ca74caaa53e1fd31ecb56cb6b70f1825 Mon Sep 17 00:00:00 2001
From: diegosouzapw <diego.souza.pw@gmail.com>
Date: Thu, 21 May 2026 10:52:37 -0300
Subject: [PATCH] fix(settings): append Global System Prompt after
 provider/agent instructions (#2468)

---
 open-sse/services/systemPrompt.ts | 13 ++++++++-----
 tests/unit/system-prompt.test.ts  | 18 ++++++++++--------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/open-sse/services/systemPrompt.ts b/open-sse/services/systemPrompt.ts
index f584a011aa..95dce9100a 100644
--- a/open-sse/services/systemPrompt.ts
+++ b/open-sse/services/systemPrompt.ts
@@ -44,21 +44,24 @@ export function injectSystemPrompt(body, promptText = null) {
     const sysIdx = result.messages.findIndex((m) => m.role === "system" || m.role === "developer");
     result.messages = [...result.messages];
     if (sysIdx >= 0) {
-      // Prepend to existing system message
+      // Append after existing system content so the global prompt is the FINAL
+      // instruction — provider/agent system blocks (Kiro, OpenCode, Hermes, etc.)
+      // are injected into the system message later, and recency bias means the
+      // user's global prompt must come after them to take priority (#2468).
       const msg = { ...result.messages[sysIdx] };
-      msg.content = text + "\n\n" + (msg.content || "");
+      msg.content = (msg.content || "") + "\n\n" + text;
       result.messages[sysIdx] = msg;
     } else {
       result.messages = [{ role: "system", content: text }, ...result.messages];
     }
   }
 
-  // Claude format (system field)
+  // Claude format (system field) — append for the same reason as above (#2468).
   if (result.system !== undefined) {
     if (typeof result.system === "string") {
-      result.system = text + "\n\n" + result.system;
+      result.system = result.system + "\n\n" + text;
     } else if (Array.isArray(result.system)) {
-      result.system = [{ type: "text", text }, ...result.system];
+      result.system = [...result.system, { type: "text", text }];
     }
   }
 
diff --git a/tests/unit/system-prompt.test.ts b/tests/unit/system-prompt.test.ts
index a90ff52bdd..fa53470988 100644
--- a/tests/unit/system-prompt.test.ts
+++ b/tests/unit/system-prompt.test.ts
@@ -30,7 +30,7 @@ test("injectSystemPrompt: adds system message when none exists", () => {
   assert.equal(result.messages.length, 2);
 });
 
-test("injectSystemPrompt: prepends to existing system message", () => {
+test("injectSystemPrompt: appends after existing system message (#2468)", () => {
   setSystemPromptConfig({ enabled: true, prompt: "GLOBAL:" });
   const body = {
     messages: [
@@ -39,23 +39,24 @@ test("injectSystemPrompt: prepends to existing system message", () => {
     ],
   };
   const result = injectSystemPrompt(body);
-  assert.ok(result.messages[0].content.startsWith("GLOBAL:"));
-  assert.ok(result.messages[0].content.includes("Original prompt"));
+  // Global prompt must be the FINAL instruction so it wins over provider/agent blocks.
+  assert.ok(result.messages[0].content.startsWith("Original prompt"));
+  assert.ok(result.messages[0].content.trimEnd().endsWith("GLOBAL:"));
   assert.equal(result.messages.length, 2);
 });
 
-test("injectSystemPrompt: Claude body.system field", () => {
+test("injectSystemPrompt: Claude body.system field appends global last (#2468)", () => {
   setSystemPromptConfig({ enabled: true, prompt: "GLOBAL:" });
   const body = {
     system: "Claude prompt",
     messages: [{ role: "user", content: "hi" }],
   };
   const result = injectSystemPrompt(body);
-  assert.ok(result.system.startsWith("GLOBAL:"));
-  assert.ok(result.system.includes("Claude prompt"));
+  assert.ok(result.system.startsWith("Claude prompt"));
+  assert.ok(result.system.trimEnd().endsWith("GLOBAL:"));
 });
 
-test("injectSystemPrompt: Claude array system field", () => {
+test("injectSystemPrompt: Claude array system field appends global last (#2468)", () => {
   setSystemPromptConfig({ enabled: true, prompt: "GLOBAL:" });
   const body = {
     system: [{ type: "text", text: "Claude prompt" }],
@@ -63,7 +64,8 @@ test("injectSystemPrompt: Claude array system field", () => {
   };
   const result = injectSystemPrompt(body);
   assert.ok(Array.isArray(result.system));
-  assert.equal(result.system[0].text, "GLOBAL:");
+  assert.equal(result.system[0].text, "Claude prompt");
+  assert.equal(result.system[result.system.length - 1].text, "GLOBAL:");
   assert.equal(result.system.length, 2);
 });