fix(agents): stabilize overflow compaction retries and session context accounting (openclaw#14102) thanks @vpesh

Verified:
- CI checks for commit 86a7ecb45e
- Rebase conflict resolution for compatibility with latest main

Co-authored-by: vpesh <9496634+vpesh@users.noreply.github.com>

src/agents/usage.test.ts

@@ -74,4 +74,19 @@ describe("normalizeUsage", () => {
       }),
     ).toBe(1_550);
   });
+
+  it("prefers explicit prompt token overrides", () => {
+    expect(
+      deriveSessionTotalTokens({
+        usage: {
+          input: 1_200,
+          cacheRead: 300,
+          cacheWrite: 50,
+          total: 9_999,
+        },
+        promptTokens: 65_000,
+        contextTokens: 200_000,
+      }),
+    ).toBe(65_000);
+  });
 });