fix: update totalTokens after compaction using last-call usage (#15018)

Merged via /review-pr -> /prepare-pr -> /merge-pr.

Prepared head SHA: 9214291bf7
Co-authored-by: shtse8 <8020099+shtse8@users.noreply.github.com>
Co-authored-by: gumadeiras <5599352+gumadeiras@users.noreply.github.com>
Reviewed-by: @gumadeiras

src/auto-reply/reply/session-usage.test.ts

@@ -0,0 +1,95 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { describe, expect, it } from "vitest";
+import { persistSessionUsageUpdate } from "./session-usage.js";
+
+async function seedSessionStore(params: {
+  storePath: string;
+  sessionKey: string;
+  entry: Record<string, unknown>;
+}) {
+  await fs.mkdir(path.dirname(params.storePath), { recursive: true });
+  await fs.writeFile(
+    params.storePath,
+    JSON.stringify({ [params.sessionKey]: params.entry }, null, 2),
+    "utf-8",
+  );
+}
+
+describe("persistSessionUsageUpdate", () => {
+  it("uses lastCallUsage for totalTokens when provided", async () => {
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-usage-"));
+    const storePath = path.join(tmp, "sessions.json");
+    const sessionKey = "main";
+    await seedSessionStore({
+      storePath,
+      sessionKey,
+      entry: { sessionId: "s1", updatedAt: Date.now(), totalTokens: 100_000 },
+    });
+
+    // Accumulated usage (sums all API calls) — inflated
+    const accumulatedUsage = { input: 180_000, output: 10_000, total: 190_000 };
+    // Last individual API call's usage — actual context after compaction
+    const lastCallUsage = { input: 12_000, output: 2_000, total: 14_000 };
+
+    await persistSessionUsageUpdate({
+      storePath,
+      sessionKey,
+      usage: accumulatedUsage,
+      lastCallUsage,
+      contextTokensUsed: 200_000,
+    });
+
+    const stored = JSON.parse(await fs.readFile(storePath, "utf-8"));
+    // totalTokens should reflect lastCallUsage (12_000 input), not accumulated (180_000)
+    expect(stored[sessionKey].totalTokens).toBe(12_000);
+    // inputTokens/outputTokens still reflect accumulated usage for cost tracking
+    expect(stored[sessionKey].inputTokens).toBe(180_000);
+    expect(stored[sessionKey].outputTokens).toBe(10_000);
+  });
+
+  it("falls back to accumulated usage for totalTokens when lastCallUsage not provided", async () => {
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-usage-"));
+    const storePath = path.join(tmp, "sessions.json");
+    const sessionKey = "main";
+    await seedSessionStore({
+      storePath,
+      sessionKey,
+      entry: { sessionId: "s1", updatedAt: Date.now() },
+    });
+
+    await persistSessionUsageUpdate({
+      storePath,
+      sessionKey,
+      usage: { input: 50_000, output: 5_000, total: 55_000 },
+      contextTokensUsed: 200_000,
+    });
+
+    const stored = JSON.parse(await fs.readFile(storePath, "utf-8"));
+    expect(stored[sessionKey].totalTokens).toBe(50_000);
+  });
+
+  it("caps totalTokens at context window even with lastCallUsage", async () => {
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-usage-"));
+    const storePath = path.join(tmp, "sessions.json");
+    const sessionKey = "main";
+    await seedSessionStore({
+      storePath,
+      sessionKey,
+      entry: { sessionId: "s1", updatedAt: Date.now() },
+    });
+
+    await persistSessionUsageUpdate({
+      storePath,
+      sessionKey,
+      usage: { input: 300_000, output: 10_000, total: 310_000 },
+      lastCallUsage: { input: 250_000, output: 5_000, total: 255_000 },
+      contextTokensUsed: 200_000,
+    });
+
+    const stored = JSON.parse(await fs.readFile(storePath, "utf-8"));
+    // Capped at context window
+    expect(stored[sessionKey].totalTokens).toBe(200_000);
+  });
+});