fix(runtime): include day of week in system prompt date/time injection (#9899)

codex · Ash (Bug Lab) · commit ffb1807647d4 · 2026-03-03T10:39:12.000+05:30
diff --git a/src/agents/system-prompt.test.ts b/src/agents/system-prompt.test.ts
@@ -350,7 +350,7 @@ describe("buildAgentSystemPrompt", () => {
     expect(prompt).toContain("Reminder: commit your changes in this workspace after edits.");
   });
 
-  it("shows timezone section for 12h, 24h, and timezone-only modes", () => {
+  it("shows current date/time when available, with timezone-only fallback", () => {
     const cases = [
       {
         name: "12-hour",
@@ -360,6 +360,7 @@ describe("buildAgentSystemPrompt", () => {
           userTime: "Monday, January 5th, 2026 — 3:26 PM",
           userTimeFormat: "12" as const,
         },
+        expectedLine: "Monday, January 5th, 2026 — 3:26 PM (America/Chicago)",
       },
       {
         name: "24-hour",
@@ -369,6 +370,7 @@ describe("buildAgentSystemPrompt", () => {
           userTime: "Monday, January 5th, 2026 — 15:26",
           userTimeFormat: "24" as const,
         },
+        expectedLine: "Monday, January 5th, 2026 — 15:26 (America/Chicago)",
       },
       {
         name: "timezone-only",
@@ -377,13 +379,14 @@ describe("buildAgentSystemPrompt", () => {
           userTimezone: "America/Chicago",
           userTimeFormat: "24" as const,
         },
+        expectedLine: "Time zone: America/Chicago",
       },
     ] as const;
 
     for (const testCase of cases) {
       const prompt = buildAgentSystemPrompt(testCase.params);
       expect(prompt, testCase.name).toContain("## Current Date & Time");
-      expect(prompt, testCase.name).toContain("Time zone: America/Chicago");
+      expect(prompt, testCase.name).toContain(testCase.expectedLine);
     }
   });
 
@@ -397,29 +400,15 @@ describe("buildAgentSystemPrompt", () => {
     expect(prompt).toContain("current date");
   });
 
-  // The system prompt intentionally does NOT include the current date/time.
-  // Only the timezone is included, to keep the prompt stable for caching.
-  // See: https://github.com/moltbot/moltbot/commit/66eec295b894bce8333886cfbca3b960c57c4946
-  // Agents should use session_status or message timestamps to determine the date/time.
-  // Related: https://github.com/moltbot/moltbot/issues/1897
-  //          https://github.com/moltbot/moltbot/issues/3658
-  it("does NOT include a date or time in the system prompt (cache stability)", () => {
+  it("includes provided date/time in the system prompt", () => {
     const prompt = buildAgentSystemPrompt({
       workspaceDir: "/tmp/clawd",
       userTimezone: "America/Chicago",
       userTime: "Monday, January 5th, 2026 — 3:26 PM",
       userTimeFormat: "12",
     });
 
-    // The prompt should contain the timezone but NOT the formatted date/time string.
-    // This is intentional for prompt cache stability — the date/time was removed in
-    // commit 66eec295b. If you're here because you want to add it back, please see
-    // https://github.com/moltbot/moltbot/issues/3658 for the preferred approach:
-    // gateway-level timestamp injection into messages, not the system prompt.
-    expect(prompt).toContain("Time zone: America/Chicago");
-    expect(prompt).not.toContain("Monday, January 5th, 2026");
-    expect(prompt).not.toContain("3:26 PM");
-    expect(prompt).not.toContain("15:26");
+    expect(prompt).toContain("Monday, January 5th, 2026 — 3:26 PM (America/Chicago)");
   });
 
   it("includes model alias guidance when aliases are provided", () => {
diff --git a/src/agents/system-prompt.ts b/src/agents/system-prompt.ts
@@ -93,11 +93,15 @@ function buildOwnerIdentityLine(
   return `Authorized senders: ${displayOwnerNumbers.join(", ")}. These senders are allowlisted; do not assume they are the owner.`;
 }
 
-function buildTimeSection(params: { userTimezone?: string }) {
+function buildTimeSection(params: { userTimezone?: string; userTime?: string }) {
   if (!params.userTimezone) {
     return [];
   }
-  return ["## Current Date & Time", `Time zone: ${params.userTimezone}`, ""];
+  const formattedTime = params.userTime?.trim();
+  const timeLine = formattedTime
+    ? `${formattedTime} (${params.userTimezone})`
+    : `Time zone: ${params.userTimezone}`;
+  return ["## Current Date & Time", timeLine, ""];
 }
 
 function buildReplyTagsSection(isMinimal: boolean) {
@@ -361,6 +365,7 @@ export function buildAgentSystemPrompt(params: {
     : undefined;
   const reasoningLevel = params.reasoningLevel ?? "off";
   const userTimezone = params.userTimezone?.trim();
+  const userTime = params.userTime?.trim();
   const skillsPrompt = params.skillsPrompt?.trim();
   const heartbeatPrompt = params.heartbeatPrompt?.trim();
   const heartbeatPromptLine = heartbeatPrompt
@@ -559,6 +564,7 @@ export function buildAgentSystemPrompt(params: {
     ...buildUserIdentitySection(ownerLine, isMinimal),
     ...buildTimeSection({
       userTimezone,
+      userTime,
     }),
     "## Workspace Files (injected)",
     "These user-editable files are loaded by OpenClaw and included below in Project Context.",
