feat: standardize timestamps to UTC

src/agents/pi-embedded-runner.ts

@@ -116,6 +116,46 @@ function resolveGlobalLane(lane?: string) {
   return cleaned ? cleaned : "main";
 }
 
+function resolveUserTimezone(configured?: string): string {
+  const trimmed = configured?.trim();
+  if (trimmed) {
+    try {
+      new Intl.DateTimeFormat("en-US", { timeZone: trimmed }).format(
+        new Date(),
+      );
+      return trimmed;
+    } catch {
+      // ignore invalid timezone
+    }
+  }
+  const host = Intl.DateTimeFormat().resolvedOptions().timeZone;
+  return host?.trim() || "UTC";
+}
+
+function formatUserTime(date: Date, timeZone: string): string | undefined {
+  try {
+    const parts = new Intl.DateTimeFormat("en-CA", {
+      timeZone,
+      year: "numeric",
+      month: "2-digit",
+      day: "2-digit",
+      hour: "2-digit",
+      minute: "2-digit",
+      hourCycle: "h23",
+    }).formatToParts(date);
+    const map: Record<string, string> = {};
+    for (const part of parts) {
+      if (part.type !== "literal") map[part.type] = part.value;
+    }
+    if (!map.year || !map.month || !map.day || !map.hour || !map.minute) {
+      return undefined;
+    }
+    return `${map.year}-${map.month}-${map.day} ${map.hour}:${map.minute}`;
+  } catch {
+    return undefined;
+  }
+}
+
 export function buildEmbeddedSandboxInfo(
   sandbox?: Awaited<ReturnType<typeof resolveSandboxContext>>,
 ): EmbeddedSandboxInfo | undefined {
@@ -398,6 +438,10 @@ export async function runEmbeddedPiAgent(params: {
           };
           const sandboxInfo = buildEmbeddedSandboxInfo(sandbox);
           const reasoningTagHint = provider === "ollama";
+          const userTimezone = resolveUserTimezone(
+            params.config?.agent?.userTimezone,
+          );
+          const userTime = formatUserTime(new Date(), userTimezone);
           const systemPrompt = buildSystemPrompt({
             appendPrompt: buildAgentSystemPromptAppend({
               workspaceDir: resolvedWorkspace,
@@ -408,6 +452,8 @@ export async function runEmbeddedPiAgent(params: {
               runtimeInfo,
               sandboxInfo,
               toolNames: tools.map((tool) => tool.name),
+              userTimezone,
+              userTime,
             }),
             contextFiles,
             skills: promptSkills,

src/agents/system-prompt.test.ts

@@ -46,4 +46,16 @@ describe("buildAgentSystemPromptAppend", () => {
     expect(prompt).toContain("sessions_send");
     expect(prompt).toContain("Unavailable tools (do not call):");
   });
+
+  it("includes user time when provided", () => {
+    const prompt = buildAgentSystemPromptAppend({
+      workspaceDir: "/tmp/clawd",
+      userTimezone: "America/Chicago",
+      userTime: "2026-01-05 15:26",
+    });
+
+    expect(prompt).toContain("## Time");
+    expect(prompt).toContain("User timezone: America/Chicago");
+    expect(prompt).toContain("Current user time: 2026-01-05 15:26");
+  });
 });

src/agents/system-prompt.ts

@@ -7,6 +7,8 @@ export function buildAgentSystemPromptAppend(params: {
   ownerNumbers?: string[];
   reasoningTagHint?: boolean;
   toolNames?: string[];
+  userTimezone?: string;
+  userTime?: string;
   runtimeInfo?: {
     host?: string;
     os?: string;
@@ -109,6 +111,8 @@ export function buildAgentSystemPromptAppend(params: {
         "<final>Hey there! What would you like to do next?</final>",
       ].join(" ")
     : undefined;
+  const userTimezone = params.userTimezone?.trim();
+  const userTime = params.userTime?.trim();
   const runtimeInfo = params.runtimeInfo;
   const runtimeLines: string[] = [];
   if (runtimeInfo?.host) runtimeLines.push(`Host: ${runtimeInfo.host}`);
@@ -182,6 +186,10 @@ export function buildAgentSystemPromptAppend(params: {
     "Never send streaming/partial replies to external messaging surfaces; only final replies should be delivered there.",
     "Clawdbot handles message transport automatically; respond normally and your reply will be delivered to the current chat.",
     "",
+    userTimezone || userTime ? "## Time" : "",
+    userTimezone ? `User timezone: ${userTimezone}` : "",
+    userTime ? `Current user time: ${userTime}` : "",
+    userTimezone || userTime ? "" : "",
     "## Reply Tags",
     "To request a native reply/quote on supported surfaces, include one tag in your reply:",
     "- [[reply_to_current]] replies to the triggering message.",