From 5c38d17c4bb4bc7a0e03a1ee2f3365efe08378a8 Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Thu, 8 Jan 2026 00:08:22 +0000
Subject: [PATCH] refactor: dedupe embedded prompt append

---
 src/agents/pi-embedded-runner.test.ts |  8 +++++
 src/agents/pi-embedded-runner.ts      | 44 ++++++++++++++++++++++++---
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/src/agents/pi-embedded-runner.test.ts b/src/agents/pi-embedded-runner.test.ts
index 194f233fc..3b581ea4a 100644
--- a/src/agents/pi-embedded-runner.test.ts
+++ b/src/agents/pi-embedded-runner.test.ts
@@ -119,10 +119,18 @@ describe("createSystemPromptAppender", () => {
     const appender = createSystemPromptAppender("APPEND_SECTION");
     const finalPrompt = appender(defaultPrompt);
     const occurrences = finalPrompt.split(sentinel).length - 1;
+    const contextHeaders = finalPrompt.split("# Project Context").length - 1;
     expect(typeof appender).toBe("function");
     expect(occurrences).toBe(1);
+    expect(contextHeaders).toBe(1);
     expect(finalPrompt).toContain("APPEND_SECTION");
   });
+
+  it("returns the default prompt when append text is empty", () => {
+    const defaultPrompt = buildSystemPrompt({ cwd: "/tmp" });
+    const appender = createSystemPromptAppender("  \n  ");
+    expect(appender(defaultPrompt)).toBe(defaultPrompt);
+  });
 });
 
 describe("applyGoogleTurnOrderingFix", () => {
diff --git a/src/agents/pi-embedded-runner.ts b/src/agents/pi-embedded-runner.ts
index f3b3bbb39..2b4169521 100644
--- a/src/agents/pi-embedded-runner.ts
+++ b/src/agents/pi-embedded-runner.ts
@@ -491,6 +491,42 @@ export function buildEmbeddedSandboxInfo(
   };
 }
 
+function buildEmbeddedAppendPrompt(params: {
+  workspaceDir: string;
+  defaultThinkLevel?: ThinkLevel;
+  extraSystemPrompt?: string;
+  ownerNumbers?: string[];
+  reasoningTagHint: boolean;
+  heartbeatPrompt?: string;
+  runtimeInfo: {
+    host: string;
+    os: string;
+    arch: string;
+    node: string;
+    model: string;
+  };
+  sandboxInfo?: EmbeddedSandboxInfo;
+  tools: AgentTool[];
+  modelAliasLines: string[];
+  userTimezone: string;
+  userTime?: string;
+}): string {
+  return buildAgentSystemPromptAppend({
+    workspaceDir: params.workspaceDir,
+    defaultThinkLevel: params.defaultThinkLevel,
+    extraSystemPrompt: params.extraSystemPrompt,
+    ownerNumbers: params.ownerNumbers,
+    reasoningTagHint: params.reasoningTagHint,
+    heartbeatPrompt: params.heartbeatPrompt,
+    runtimeInfo: params.runtimeInfo,
+    sandboxInfo: params.sandboxInfo,
+    toolNames: params.tools.map((tool) => tool.name),
+    modelAliasLines: params.modelAliasLines,
+    userTimezone: params.userTimezone,
+    userTime: params.userTime,
+  });
+}
+
 export function createSystemPromptAppender(
   appendPrompt: string,
 ): (defaultPrompt: string) => string {
@@ -784,7 +820,7 @@ export async function compactEmbeddedPiSession(params: {
           params.config?.agent?.userTimezone,
         );
         const userTime = formatUserTime(new Date(), userTimezone);
-        const appendPrompt = buildAgentSystemPromptAppend({
+        const appendPrompt = buildEmbeddedAppendPrompt({
           workspaceDir: effectiveWorkspace,
           defaultThinkLevel: params.thinkLevel,
           extraSystemPrompt: params.extraSystemPrompt,
@@ -795,7 +831,7 @@ export async function compactEmbeddedPiSession(params: {
           ),
           runtimeInfo,
           sandboxInfo,
-          toolNames: tools.map((tool) => tool.name),
+          tools,
           modelAliasLines: buildModelAliasLines(params.config),
           userTimezone,
           userTime,
@@ -1104,7 +1140,7 @@ export async function runEmbeddedPiAgent(params: {
             params.config?.agent?.userTimezone,
           );
           const userTime = formatUserTime(new Date(), userTimezone);
-          const appendPrompt = buildAgentSystemPromptAppend({
+          const appendPrompt = buildEmbeddedAppendPrompt({
             workspaceDir: effectiveWorkspace,
             defaultThinkLevel: thinkLevel,
             extraSystemPrompt: params.extraSystemPrompt,
@@ -1115,7 +1151,7 @@ export async function runEmbeddedPiAgent(params: {
             ),
             runtimeInfo,
             sandboxInfo,
-            toolNames: tools.map((tool) => tool.name),
+            tools,
             modelAliasLines: buildModelAliasLines(params.config),
             userTimezone,
             userTime,