feat: add "Current Date:" label to timestamp prefix

Changes [Wed 2026-01-28 20:30 EST] to [Current Date: Wed 2026-01-28 20:30 EST].

Tested with qwen3-1.7B: even with DOW in the timestamp, the model
ignored it and tried to compute the day using Zeller's Congruence.
The "Current Date:" semantic label is widely present in training data
and gives small models the best chance of recognizing the timestamp
as authoritative context rather than metadata to parse.

Cost: ~18 tokens per message. Prevents hallucination spirals that
burn hundreds or thousands of tokens on date derivation.

src/gateway/server-methods/agent-timestamp.test.ts

@@ -18,7 +18,7 @@ describe("injectTimestamp", () => {
       timezone: "America/New_York",
     });
 
-    expect(result).toMatch(/^\[Wed 2026-01-28 20:30 EST\] Is it the weekend\?$/);
+    expect(result).toMatch(/^\[Current Date: Wed 2026-01-28 20:30 EST\] Is it the weekend\?$/);
   });
 
   it("uses channel envelope format with DOW prefix", () => {
@@ -28,7 +28,7 @@ describe("injectTimestamp", () => {
     const result = injectTimestamp("hello", { timezone: "America/New_York" });
 
     // DOW prefix + formatZonedTimestamp format
-    expect(result).toBe(`[Wed ${expected}] hello`);
+    expect(result).toBe(`[Current Date: Wed ${expected}] hello`);
   });
 
   it("always uses 24-hour format", () => {
@@ -43,14 +43,14 @@ describe("injectTimestamp", () => {
     const result = injectTimestamp("hello", { timezone: "America/Chicago" });
 
     // 8:30 PM EST = 7:30 PM CST = 19:30
-    expect(result).toMatch(/^\[Wed 2026-01-28 19:30 CST\]/);
+    expect(result).toMatch(/^\[Current Date: Wed 2026-01-28 19:30 CST\]/);
   });
 
   it("defaults to UTC when no timezone specified", () => {
     const result = injectTimestamp("hello", {});
 
     // 2026-01-29T01:30:00Z
-    expect(result).toMatch(/^\[Thu 2026-01-29 01:30/);
+    expect(result).toMatch(/^\[Current Date: Thu 2026-01-29 01:30/);
   });
 
   it("returns empty/whitespace messages unchanged", () => {
@@ -66,7 +66,7 @@ describe("injectTimestamp", () => {
   });
 
   it("does NOT double-stamp messages already injected by us", () => {
-    const alreadyStamped = "[Wed 2026-01-28 20:30 EST] hello there";
+    const alreadyStamped = "[Current Date: Wed 2026-01-28 20:30 EST] hello there";
     const result = injectTimestamp(alreadyStamped, { timezone: "America/New_York" });
 
     expect(result).toBe(alreadyStamped);
@@ -85,7 +85,7 @@ describe("injectTimestamp", () => {
 
     const result = injectTimestamp("hello", { timezone: "America/New_York" });
 
-    expect(result).toMatch(/^\[Sun 2026-02-01 00:00 EST\]/);
+    expect(result).toMatch(/^\[Current Date: Sun 2026-02-01 00:00 EST\]/);
   });
 
   it("handles date boundaries (just before midnight)", () => {
@@ -93,19 +93,19 @@ describe("injectTimestamp", () => {
 
     const result = injectTimestamp("hello", { timezone: "America/New_York" });
 
-    expect(result).toMatch(/^\[Sat 2026-01-31 23:59 EST\]/);
+    expect(result).toMatch(/^\[Current Date: Sat 2026-01-31 23:59 EST\]/);
   });
 
   it("handles DST correctly (same UTC hour, different local time)", () => {
     // EST (winter): UTC-5 → 2026-01-15T05:00Z = midnight Jan 15
     vi.setSystemTime(new Date("2026-01-15T05:00:00.000Z"));
     const winter = injectTimestamp("winter", { timezone: "America/New_York" });
-    expect(winter).toMatch(/^\[Thu 2026-01-15 00:00 EST\]/);
+    expect(winter).toMatch(/^\[Current Date: Thu 2026-01-15 00:00 EST\]/);
 
     // EDT (summer): UTC-4 → 2026-07-15T04:00Z = midnight Jul 15
     vi.setSystemTime(new Date("2026-07-15T04:00:00.000Z"));
     const summer = injectTimestamp("summer", { timezone: "America/New_York" });
-    expect(summer).toMatch(/^\[Wed 2026-07-15 00:00 EDT\]/);
+    expect(summer).toMatch(/^\[Current Date: Wed 2026-07-15 00:00 EDT\]/);
   });
 
   it("accepts a custom now date", () => {
@@ -116,7 +116,7 @@ describe("injectTimestamp", () => {
       now: customDate,
     });
 
-    expect(result).toMatch(/^\[Fri 2025-07-04 12:00 EDT\]/);
+    expect(result).toMatch(/^\[Current Date: Fri 2025-07-04 12:00 EDT\]/);
   });
 });
 

src/gateway/server-methods/agent-timestamp.ts

@@ -53,13 +53,14 @@ export function injectTimestamp(message: string, opts?: TimestampInjectionOption
   const formatted = formatZonedTimestamp(now, timezone);
   if (!formatted) return message;
 
-  // Add 3-letter day-of-week for smaller models that can't derive DOW
-  // from a date. Costs ~1 token, cheap insurance.
+  // "Current Date:" label is unambiguous even for tiny models (1.7B+).
+  // 3-letter DOW included because small models can't derive it from a date.
+  // Total cost: ~18 tokens — saves thousands when it prevents hallucination.
   const dow = new Intl.DateTimeFormat("en-US", { timeZone: timezone, weekday: "short" }).format(
     now,
   );
 
-  return `[${dow} ${formatted}] ${message}`;
+  return `[Current Date: ${dow} ${formatted}] ${message}`;
 }
 
 /**

src/gateway/server-methods/agent.test.ts

@@ -163,7 +163,7 @@ describe("gateway agent handler", () => {
     await vi.waitFor(() => expect(mocks.agentCommand).toHaveBeenCalled());
 
     const callArgs = mocks.agentCommand.mock.calls[0][0];
-    expect(callArgs.message).toBe("[Wed 2026-01-28 20:30 EST] Is it the weekend?");
+    expect(callArgs.message).toBe("[Current Date: Wed 2026-01-28 20:30 EST] Is it the weekend?");
 
     mocks.loadConfigReturn = {};
     vi.useRealTimers();