diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8bda620ac1..7de75be6b10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@ Docs: https://docs.openclaw.ai
 - Agents/fallback: preserve the original prompt body on model fallback retries with session history so the retrying model keeps the active task instead of only seeing a generic continue message. (#66029) Thanks @WuKongAI-CMU.
 - Reply/secrets: resolve active reply channel/account SecretRefs before reply-run message-action discovery so channel token SecretRefs (for example Discord) do not degrade into discovery-time unresolved-secret failures. (#66796) Thanks @joshavant.
 - Agents/Anthropic: ignore non-positive Anthropic Messages token overrides and fail locally when no positive token budget remains, so invalid `max_tokens` values no longer reach the provider API. (#66664) thanks @jalehman
+- Agents/context engines: preserve prompt-only token counts, not full request totals, when deferred maintenance reuses after-turn runtime context so background compaction bookkeeping matches the active prompt window. (#66820) thanks @jalehman.
 
 ## 2026.4.14
 
diff --git a/src/agents/pi-embedded-runner/context-engine-maintenance.test.ts b/src/agents/pi-embedded-runner/context-engine-maintenance.test.ts
index b396ca8f51d..ec600053d40 100644
--- a/src/agents/pi-embedded-runner/context-engine-maintenance.test.ts
+++ b/src/agents/pi-embedded-runner/context-engine-maintenance.test.ts
@@ -424,7 +424,11 @@ describe("runContextEngineMaintenance", () => {
           sessionKey,
           sessionFile: "/tmp/session.jsonl",
           reason: "turn",
-          runtimeContext: { workspaceDir: "/tmp/workspace" },
+          runtimeContext: {
+            workspaceDir: "/tmp/workspace",
+            tokenBudget: 2048,
+            currentTokenCount: 1536,
+          },
         });
 
         expect(result).toBeUndefined();
@@ -453,6 +457,8 @@ describe("runContextEngineMaintenance", () => {
           runtimeContext: expect.objectContaining({
             workspaceDir: "/tmp/workspace",
             allowDeferredCompactionExecution: true,
+            tokenBudget: 2048,
+            currentTokenCount: 1536,
           }),
         });
 
diff --git a/src/agents/pi-embedded-runner/run/attempt.prompt-helpers.ts b/src/agents/pi-embedded-runner/run/attempt.prompt-helpers.ts
index 767f496ff24..6aaa470ee64 100644
--- a/src/agents/pi-embedded-runner/run/attempt.prompt-helpers.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.prompt-helpers.ts
@@ -226,6 +226,8 @@ export function buildAfterTurnRuntimeContext(params: {
   >;
   workspaceDir: string;
   agentDir: string;
+  tokenBudget?: number;
+  currentTokenCount?: number;
   promptCache?: ContextEnginePromptCacheInfo;
 }): ContextEngineRuntimeContext {
   return {
@@ -252,6 +254,16 @@ export function buildAfterTurnRuntimeContext(params: {
       extraSystemPrompt: params.attempt.extraSystemPrompt,
       ownerNumbers: params.attempt.ownerNumbers,
     }),
+    ...(typeof params.tokenBudget === "number" &&
+      Number.isFinite(params.tokenBudget) &&
+      params.tokenBudget > 0
+      ? { tokenBudget: Math.floor(params.tokenBudget) }
+      : {}),
+    ...(typeof params.currentTokenCount === "number" &&
+      Number.isFinite(params.currentTokenCount) &&
+      params.currentTokenCount > 0
+      ? { currentTokenCount: Math.floor(params.currentTokenCount) }
+      : {}),
     ...(params.promptCache ? { promptCache: params.promptCache } : {}),
   };
 }
diff --git a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
index 2f45a46c1b7..a2817885639 100644
--- a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.context-engine.test.ts
@@ -14,6 +14,8 @@ import {
   runAttemptContextEngineBootstrap,
 } from "./attempt.context-engine-helpers.js";
 import {
+  cleanupTempPaths,
+  createContextEngineAttemptRunner,
   createContextEngineBootstrapAndAssemble,
   expectCalledWithSessionKey,
   getHoisted,
@@ -109,6 +111,7 @@ async function finalizeTurn(
 
 describe("runEmbeddedAttempt context engine sessionKey forwarding", () => {
   const sessionKey = "agent:main:discord:channel:test-ctx-engine";
+  const tempPaths: string[] = [];
   beforeEach(() => {
     resetEmbeddedAttemptHarness();
     clearMemoryPluginState();
@@ -116,6 +119,7 @@ describe("runEmbeddedAttempt context engine sessionKey forwarding", () => {
   });
 
   afterEach(async () => {
+    await cleanupTempPaths(tempPaths);
     clearMemoryPluginState();
     vi.restoreAllMocks();
   });
@@ -395,6 +399,59 @@ describe("runEmbeddedAttempt context engine sessionKey forwarding", () => {
     );
   });
 
+  it("derives deferred maintenance currentTokenCount from prompt-only usage", async () => {
+    const afterTurn = vi.fn(
+      async (_params: {
+        runtimeContext?: {
+          currentTokenCount?: number;
+          promptCache?: { lastCallUsage?: { total?: number } };
+        };
+      }) => {},
+    );
+
+    await createContextEngineAttemptRunner({
+      sessionKey,
+      tempPaths,
+      contextEngine: {
+        assemble: async ({ messages }) => ({
+          messages,
+          estimatedTokens: 1,
+        }),
+        afterTurn,
+      },
+      sessionPrompt: async (session) => {
+        session.messages = [
+          ...session.messages,
+          {
+            role: "assistant",
+            content: "done",
+            timestamp: 2,
+            usage: {
+              input: 10,
+              output: 5,
+              cacheRead: 40,
+              cacheWrite: 2,
+              total: 57,
+            },
+          } as unknown as AgentMessage,
+        ];
+      },
+    });
+
+    expect(afterTurn).toHaveBeenCalledWith(
+      expect.objectContaining({
+        runtimeContext: expect.objectContaining({
+          currentTokenCount: 52,
+          promptCache: expect.objectContaining({
+            lastCallUsage: expect.objectContaining({
+              total: 57,
+            }),
+          }),
+        }),
+      }),
+    );
+  });
+
   it("skips maintenance when ingestBatch fails", async () => {
     const { bootstrap, assemble } = createContextEngineBootstrapAndAssemble();
     const ingestBatch = vi.fn(async () => {
diff --git a/src/agents/pi-embedded-runner/run/attempt.test.ts b/src/agents/pi-embedded-runner/run/attempt.test.ts
index ab47465ea8a..2c93d062216 100644
--- a/src/agents/pi-embedded-runner/run/attempt.test.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.test.ts
@@ -2836,6 +2836,8 @@ describe("buildAfterTurnRuntimeContext", () => {
       },
       workspaceDir: "/tmp/workspace",
       agentDir: "/tmp/agent",
+      tokenBudget: 1050000,
+      currentTokenCount: 232393,
     });
 
     expect(legacy).toMatchObject({
@@ -2844,6 +2846,8 @@ describe("buildAfterTurnRuntimeContext", () => {
       model: "gpt-5.4",
       workspaceDir: "/tmp/workspace",
       agentDir: "/tmp/agent",
+      tokenBudget: 1050000,
+      currentTokenCount: 232393,
     });
   });
 
diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 3c3e8885499..b1a44fc05ce 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -116,7 +116,7 @@ import {
   resolveTranscriptPolicy,
   shouldAllowProviderOwnedThinkingReplay,
 } from "../../transcript-policy.js";
-import { normalizeUsage, type NormalizedUsage } from "../../usage.js";
+import { derivePromptTokens, normalizeUsage, type NormalizedUsage } from "../../usage.js";
 import { DEFAULT_BOOTSTRAP_FILENAME } from "../../workspace.js";
 import { isRunnerAbortError } from "../abort.js";
 import { isCacheTtlEligibleProvider, readLastCacheTtlTimestamp } from "../cache-ttl.js";
@@ -887,6 +887,7 @@ export async function runEmbeddedAttempt(
           attempt: params,
           workspaceDir: effectiveWorkspace,
           agentDir,
+          tokenBudget: params.contextTokenBudget,
         }),
         runMaintenance: async (contextParams) =>
           await runContextEngineMaintenance({
@@ -2201,10 +2202,13 @@ export async function runEmbeddedAttempt(
 
         // Let the active context engine run its post-turn lifecycle.
         if (params.contextEngine) {
+          const runtimeCurrentTokenCount = derivePromptTokens(lastCallUsage);
           const afterTurnRuntimeContext = buildAfterTurnRuntimeContext({
             attempt: params,
             workspaceDir: effectiveWorkspace,
             agentDir,
+            tokenBudget: params.contextTokenBudget,
+            currentTokenCount: runtimeCurrentTokenCount,
             promptCache,
           });
           await finalizeAttemptContextEngineTurn({
diff --git a/src/context-engine/types.ts b/src/context-engine/types.ts
index 594703bc864..2eea7ea7ba2 100644
--- a/src/context-engine/types.ts
+++ b/src/context-engine/types.ts
@@ -140,6 +140,10 @@ export type ContextEngineRuntimeContext = Record<string, unknown> & {
    * consuming deferred compaction debt.
    */
   allowDeferredCompactionExecution?: boolean;
+  /** Runtime-resolved context window budget for the active model call. */
+  tokenBudget?: number;
+  /** Best-effort current prompt/context token estimate for this turn. */
+  currentTokenCount?: number;
   /** Optional prompt-cache telemetry for cache-aware engines. */
   promptCache?: ContextEnginePromptCacheInfo;
   /**