feat: surface cached token counts in /status output (openclaw#21248) thanks @vishaltandale00

Verified:
- pnpm build
- pnpm check
- pnpm test:macmini

Co-authored-by: vishaltandale00 <9222298+vishaltandale00@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/config/sessions/cache-fields.test.ts

@@ -0,0 +1,68 @@
+import { describe, expect, it } from "vitest";
+import type { SessionEntry } from "./types.js";
+import { mergeSessionEntry } from "./types.js";
+
+describe("SessionEntry cache fields", () => {
+  it("supports cacheRead and cacheWrite fields", () => {
+    const entry: SessionEntry = {
+      sessionId: "test-session",
+      updatedAt: Date.now(),
+      cacheRead: 1500,
+      cacheWrite: 300,
+    };
+
+    expect(entry.cacheRead).toBe(1500);
+    expect(entry.cacheWrite).toBe(300);
+  });
+
+  it("merges cache fields properly", () => {
+    const existing: SessionEntry = {
+      sessionId: "test-session",
+      updatedAt: Date.now(),
+      cacheRead: 1000,
+      cacheWrite: 200,
+      totalTokens: 5000,
+    };
+
+    const patch: Partial<SessionEntry> = {
+      cacheRead: 1500,
+      cacheWrite: 300,
+    };
+
+    const merged = mergeSessionEntry(existing, patch);
+
+    expect(merged.cacheRead).toBe(1500);
+    expect(merged.cacheWrite).toBe(300);
+    expect(merged.totalTokens).toBe(5000); // Preserved from existing
+  });
+
+  it("handles undefined cache fields", () => {
+    const entry: SessionEntry = {
+      sessionId: "test-session",
+      updatedAt: Date.now(),
+      totalTokens: 5000,
+    };
+
+    expect(entry.cacheRead).toBeUndefined();
+    expect(entry.cacheWrite).toBeUndefined();
+  });
+
+  it("allows cache fields to be cleared with undefined", () => {
+    const existing: SessionEntry = {
+      sessionId: "test-session",
+      updatedAt: Date.now(),
+      cacheRead: 1000,
+      cacheWrite: 200,
+    };
+
+    const patch: Partial<SessionEntry> = {
+      cacheRead: undefined,
+      cacheWrite: undefined,
+    };
+
+    const merged = mergeSessionEntry(existing, patch);
+
+    expect(merged.cacheRead).toBeUndefined();
+    expect(merged.cacheWrite).toBeUndefined();
+  });
+});

src/config/sessions/types.ts

@@ -78,6 +78,8 @@ export type SessionEntry = {
    * totalTokens as stale/unknown for context-utilization displays.
    */
   totalTokensFresh?: boolean;
+  cacheRead?: number;
+  cacheWrite?: number;
   modelProvider?: string;
   model?: string;
   /**