diff --git a/assistant/src/__tests__/config-schema.test.ts b/assistant/src/__tests__/config-schema.test.ts
index 20482c4fb58..b174f1cc6f1 100644
--- a/assistant/src/__tests__/config-schema.test.ts
+++ b/assistant/src/__tests__/config-schema.test.ts
@@ -2073,6 +2073,37 @@ describe("loadConfig with schema validation", () => {
     expect(config.calls.provider).toBe("twilio");
   });
 
+  test("recovers from partial filing.activeHours without wiping unrelated fields", () => {
+    // Only activeHoursStart is set. The superRefine must emit the issue so
+    // the loader's delete-and-retry can strip the set field; otherwise the
+    // mismatch persists and the config falls back to full defaults (which
+    // would reset maxTokens below to 64000).
+    writeConfig({
+      maxTokens: 4096,
+      filing: { activeHoursStart: 8 },
+    });
+    const config = loadConfig();
+    expect(config.maxTokens).toBe(4096);
+    expect(config.filing.activeHoursStart).toBeNull();
+    expect(config.filing.activeHoursEnd).toBeNull();
+  });
+
+  test("recovers from partial heartbeat.activeHours without wiping unrelated fields", () => {
+    // activeHoursStart is explicitly nulled while activeHoursEnd defaults to
+    // 22 — a mismatch. Without emitting on both paths, delete-and-retry can't
+    // resolve this (deleting the null side is a no-op) and the whole config
+    // would be reset to defaults.
+    writeConfig({
+      maxTokens: 4096,
+      heartbeat: { activeHoursStart: null },
+    });
+    const config = loadConfig();
+    expect(config.maxTokens).toBe(4096);
+    // Both fall back to the heartbeat defaults (8, 22).
+    expect(config.heartbeat.activeHoursStart).toBe(8);
+    expect(config.heartbeat.activeHoursEnd).toBe(22);
+  });
+
   test("applies calls defaults when not specified", () => {
     writeConfig({});
     const config = loadConfig();
diff --git a/assistant/src/config/schemas/filing.ts b/assistant/src/config/schemas/filing.ts
index 335a28116f2..b0282a7ec8d 100644
--- a/assistant/src/config/schemas/filing.ts
+++ b/assistant/src/config/schemas/filing.ts
@@ -47,11 +47,20 @@ export const FilingConfigSchema = z
     const startNull = config.activeHoursStart == null;
     const endNull = config.activeHoursEnd == null;
     if (startNull !== endNull) {
+      // Emit on both fields so validateWithSchema's delete-and-retry repair
+      // can strip whichever side was set (and no-op the null side), letting
+      // the config fall back to both-null defaults without a full reset.
+      const message =
+        "filing.activeHoursStart and filing.activeHoursEnd must both be set or both be null";
       ctx.addIssue({
         code: z.ZodIssueCode.custom,
-        path: [startNull ? "activeHoursStart" : "activeHoursEnd"],
-        message:
-          "filing.activeHoursStart and filing.activeHoursEnd must both be set or both be null",
+        path: ["activeHoursStart"],
+        message,
+      });
+      ctx.addIssue({
+        code: z.ZodIssueCode.custom,
+        path: ["activeHoursEnd"],
+        message,
       });
       return;
     }
diff --git a/assistant/src/config/schemas/heartbeat.ts b/assistant/src/config/schemas/heartbeat.ts
index 528b0278a2e..efc26775e52 100644
--- a/assistant/src/config/schemas/heartbeat.ts
+++ b/assistant/src/config/schemas/heartbeat.ts
@@ -43,11 +43,20 @@ export const HeartbeatConfigSchema = z
     const startNull = config.activeHoursStart == null;
     const endNull = config.activeHoursEnd == null;
     if (startNull !== endNull) {
+      // Emit on both fields so validateWithSchema's delete-and-retry repair
+      // can strip whichever side was set (and no-op the null side), letting
+      // the config fall back to the schema defaults without a full reset.
+      const message =
+        "heartbeat.activeHoursStart and heartbeat.activeHoursEnd must both be set or both be null";
       ctx.addIssue({
         code: z.ZodIssueCode.custom,
-        path: [startNull ? "activeHoursStart" : "activeHoursEnd"],
-        message:
-          "heartbeat.activeHoursStart and heartbeat.activeHoursEnd must both be set or both be null",
+        path: ["activeHoursStart"],
+        message,
+      });
+      ctx.addIssue({
+        code: z.ZodIssueCode.custom,
+        path: ["activeHoursEnd"],
+        message,
       });
       return;
     }