diff --git a/src/node/services/workspaceService.ts b/src/node/services/workspaceService.ts
index a26e835a1..48d0739f6 100644
--- a/src/node/services/workspaceService.ts
+++ b/src/node/services/workspaceService.ts
@@ -959,6 +959,33 @@ export class WorkspaceService extends EventEmitter {
     return { model, thinkingLevel };
   }
 
+  /**
+   * Best-effort persist AI settings from send/resume options.
+   * Skips compaction requests which use a different model intentionally.
+   */
+  private async maybePersistAISettingsFromOptions(
+    workspaceId: string,
+    options: SendMessageOptions | undefined,
+    context: "send" | "resume"
+  ): Promise<void> {
+    // Skip for compaction - it may use a different model and shouldn't override user preference
+    const isCompaction = options?.mode === "compact";
+    if (isCompaction) return;
+
+    const extractedSettings = this.extractWorkspaceAISettingsFromSendOptions(options);
+    if (!extractedSettings) return;
+
+    const persistResult = await this.persistWorkspaceAISettings(workspaceId, extractedSettings, {
+      emitMetadata: false,
+    });
+    if (!persistResult.success) {
+      log.debug(`Failed to persist workspace AI settings from ${context} options`, {
+        workspaceId,
+        error: persistResult.error,
+      });
+    }
+  }
+
   private async persistWorkspaceAISettings(
     workspaceId: string,
     aiSettings: WorkspaceAISettings,
@@ -1275,23 +1302,7 @@ export class WorkspaceService extends EventEmitter {
             };
 
       // Persist last-used model + thinking level for cross-device consistency.
-      // Best-effort: failures should not block sending.
-      const extractedSettings = this.extractWorkspaceAISettingsFromSendOptions(resolvedOptions);
-      if (extractedSettings) {
-        const persistResult = await this.persistWorkspaceAISettings(
-          workspaceId,
-          extractedSettings,
-          {
-            emitMetadata: false,
-          }
-        );
-        if (!persistResult.success) {
-          log.debug("Failed to persist workspace AI settings from send options", {
-            workspaceId,
-            error: persistResult.error,
-          });
-        }
-      }
+      await this.maybePersistAISettingsFromOptions(workspaceId, resolvedOptions, "send");
 
       if (this.aiService.isStreaming(workspaceId) && !resolvedOptions?.editMessageId) {
         const pendingAskUserQuestion = askUserQuestionManager.getLatestPending(workspaceId);
@@ -1405,23 +1416,7 @@ export class WorkspaceService extends EventEmitter {
       const session = this.getOrCreateSession(workspaceId);
 
       // Persist last-used model + thinking level for cross-device consistency.
-      // Best-effort: failures should not block resuming.
-      const extractedSettings = this.extractWorkspaceAISettingsFromSendOptions(options);
-      if (extractedSettings) {
-        const persistResult = await this.persistWorkspaceAISettings(
-          workspaceId,
-          extractedSettings,
-          {
-            emitMetadata: false,
-          }
-        );
-        if (!persistResult.success) {
-          log.debug("Failed to persist workspace AI settings from resume options", {
-            workspaceId,
-            error: persistResult.error,
-          });
-        }
-      }
+      await this.maybePersistAISettingsFromOptions(workspaceId, options, "resume");
 
       const result = await session.resumeStream(options);
       if (!result.success) {
diff --git a/tests/ipc/workspaceAISettings.test.ts b/tests/ipc/workspaceAISettings.test.ts
index 00d71b6f3..5eeab1087 100644
--- a/tests/ipc/workspaceAISettings.test.ts
+++ b/tests/ipc/workspaceAISettings.test.ts
@@ -48,4 +48,56 @@ describe("workspace.updateAISettings", () => {
       await cleanupTempGitRepo(tempGitRepo);
     }
   }, 60000);
+
+  test("compaction requests do not override workspace aiSettings", async () => {
+    const env: TestEnvironment = await createTestEnvironment();
+    const tempGitRepo = await createTempGitRepo();
+
+    try {
+      const branchName = generateBranchName("ai-settings-compact");
+      const createResult = await createWorkspace(env, tempGitRepo, branchName);
+      if (!createResult.success) {
+        throw new Error(`Workspace creation failed: ${createResult.error}`);
+      }
+
+      const workspaceId = createResult.metadata.id;
+      expect(workspaceId).toBeTruthy();
+
+      const client = resolveOrpcClient(env);
+
+      // Set initial workspace AI settings
+      const updateResult = await client.workspace.updateAISettings({
+        workspaceId: workspaceId!,
+        aiSettings: { model: "anthropic:claude-sonnet-4-20250514", thinkingLevel: "medium" },
+      });
+      expect(updateResult.success).toBe(true);
+
+      // Send a compaction request with a different model
+      // The muxMetadata type: "compaction-request" should prevent AI settings from being persisted
+      await client.workspace.sendMessage({
+        workspaceId: workspaceId!,
+        message: "Summarize the conversation",
+        options: {
+          model: "openai:gpt-4.1-mini", // Different model for compaction
+          thinkingLevel: "off",
+          mode: "compact",
+          muxMetadata: {
+            type: "compaction-request",
+            rawCommand: "/compact",
+            parsed: {},
+          },
+        },
+      });
+
+      // Verify the original workspace AI settings were NOT overwritten
+      const info = await client.workspace.getInfo({ workspaceId: workspaceId! });
+      expect(info?.aiSettings).toEqual({
+        model: "anthropic:claude-sonnet-4-20250514",
+        thinkingLevel: "medium",
+      });
+    } finally {
+      await cleanupTestEnvironment(env);
+      await cleanupTempGitRepo(tempGitRepo);
+    }
+  }, 60000);
 });