fix: remove Current date from env context since OpenCode already provides it

date is already injected by OpenCode's system.ts. omo-env now contains only
Timezone and Locale, which are stable across requests and never break cache.

src/agents/env-context.test.ts

@@ -4,7 +4,7 @@ import { describe, test, expect } from "bun:test"
 import { createEnvContext } from "./env-context"
 
 describe("createEnvContext", () => {
-  test("returns omo-env block with date, timezone, and locale", () => {
+  test("returns omo-env block with timezone and locale", () => {
     // #given - no setup needed
 
     // #when
@@ -13,9 +13,9 @@ describe("createEnvContext", () => {
     // #then
     expect(result).toContain("<omo-env>")
     expect(result).toContain("</omo-env>")
-    expect(result).toContain("Current date:")
     expect(result).toContain("Timezone:")
     expect(result).toContain("Locale:")
+    expect(result).not.toContain("Current date:")
   })
 
   test("does not include time with seconds precision to preserve token cache", () => {
@@ -28,13 +28,14 @@ describe("createEnvContext", () => {
     expect(result).not.toMatch(/\d{1,2}:\d{2}:\d{2}/)
   })
 
-  test("does not include Current time field", () => {
-    // #given - time field (even without seconds) changes every minute, degrading cache
+  test("does not include date or time fields since OpenCode already provides them", () => {
+    // #given - OpenCode's system.ts already injects date, platform, working directory
 
     // #when
     const result = createEnvContext()
 
-    // #then - time field entirely removed; date-level precision is sufficient
+    // #then - only timezone and locale remain; both are stable across requests
+    expect(result).not.toContain("Current date:")
     expect(result).not.toContain("Current time:")
   })
 })