diff --git a/apps/server/src/internal/session-owner-side-effects.ts b/apps/server/src/internal/session-owner-side-effects.ts
index bc8fb94acc..65facec672 100644
--- a/apps/server/src/internal/session-owner-side-effects.ts
+++ b/apps/server/src/internal/session-owner-side-effects.ts
@@ -256,7 +256,7 @@ function completeDaemonActiveWorkDisconnectGrace(
 
   interruptActiveThreadsForHost(deps, {
     hostId: args.hostId,
-    reason: "host-daemon-restarted",
+    reason: "host-connection-lost",
   });
 }
 
diff --git a/apps/server/src/services/threads/thread-lifecycle.ts b/apps/server/src/services/threads/thread-lifecycle.ts
index b937221579..21fccb8efc 100644
--- a/apps/server/src/services/threads/thread-lifecycle.ts
+++ b/apps/server/src/services/threads/thread-lifecycle.ts
@@ -340,6 +340,7 @@ function lifecycleEventForInterruptedThread(
     case "manual-stop":
       return { type: "stop.settled" };
     case "host-daemon-restarted":
+    case "host-connection-lost":
       return { type: "run.failed" };
     // Legacy persisted watchdog interruption; no current producer. Lands on
     // "error" like a lost session.
@@ -358,6 +359,8 @@ function pendingInteractionStopReason(
       return "Thread stopped by user request";
     case "host-daemon-restarted":
       return "Host daemon restarted while awaiting user interaction";
+    case "host-connection-lost":
+      return "Connection to host was lost while awaiting user interaction";
     // Legacy persisted watchdog interruption; no current producer.
     case "provider-turn-idle":
       return "Thread stopped after the provider stopped sending progress";
@@ -374,6 +377,8 @@ function threadCommandFailureMessageForInterruption(
       return null;
     case "host-daemon-restarted":
       return "Thread interrupted because the host daemon disconnected";
+    case "host-connection-lost":
+      return "Thread interrupted because the connection to the host was lost";
     // Legacy persisted watchdog interruption; no current producer.
     case "provider-turn-idle":
       return "Live runtime work failed because the provider stopped sending progress";
@@ -389,6 +394,7 @@ function threadCommandFailureDetailForInterruption(
     case "manual-stop":
       return "Thread stopped by user request";
     case "host-daemon-restarted":
+    case "host-connection-lost":
       return "Please retry the thread to continue.";
     // Legacy persisted watchdog interruption; no current producer.
     case "provider-turn-idle":
diff --git a/apps/server/test/internal/background-task-reconciliation.test.ts b/apps/server/test/internal/background-task-reconciliation.test.ts
index 51abcb0862..b6f9e22ec4 100644
--- a/apps/server/test/internal/background-task-reconciliation.test.ts
+++ b/apps/server/test/internal/background-task-reconciliation.test.ts
@@ -503,7 +503,7 @@ describe("active thread disconnect reconciliation triggers", () => {
     });
   });
 
-  it("interrupts active turns when a different daemon instance registers", async () => {
+  it("records a confirmed daemon restart when a different daemon instance registers", async () => {
     await withTestHarness(async (harness) => {
       const { host, session, thread } = seedActiveTurnThread(harness);
 
@@ -553,7 +553,7 @@ describe("active thread disconnect reconciliation triggers", () => {
     });
   });
 
-  it("interrupts active turns after the live event window elapses without a reconnect", async () => {
+  it("records a lost host connection after the live event window elapses without a reconnect", async () => {
     await withTestHarness(async (harness) => {
       const { session, thread } = seedActiveTurnThread(harness);
 
@@ -586,13 +586,14 @@ describe("active thread disconnect reconciliation triggers", () => {
         expect.objectContaining({
           data: expect.objectContaining({
             code: "thread_command_failed",
-            message: "Thread interrupted because the host daemon disconnected",
+            message:
+              "Thread interrupted because the connection to the host was lost",
             detail: "Please retry the thread to continue.",
           }),
           type: "system/error",
         }),
         expect.objectContaining({
-          data: { reason: "host-daemon-restarted" },
+          data: { reason: "host-connection-lost" },
           type: "system/thread/interrupted",
         }),
       ]);
diff --git a/packages/domain/src/thread-events.ts b/packages/domain/src/thread-events.ts
index d14e509c2a..d9497c98dc 100644
--- a/packages/domain/src/thread-events.ts
+++ b/packages/domain/src/thread-events.ts
@@ -246,6 +246,7 @@ export const systemUserQuestionLifecycleEventDataSchema = z.object({
 const systemThreadInterruptedReasonValues = [
   "manual-stop",
   "host-daemon-restarted",
+  "host-connection-lost",
   // Legacy persisted watchdog interruption; retained for read/replay only,
   // with no current producer.
   "provider-turn-idle",
diff --git a/packages/plugin-api-map/sdk-public-api.json b/packages/plugin-api-map/sdk-public-api.json
index a506cd20af..779e53b44e 100644
--- a/packages/plugin-api-map/sdk-public-api.json
+++ b/packages/plugin-api-map/sdk-public-api.json
@@ -3,7 +3,7 @@
   "entries": {
     ".": {
       "types": "bundled-types/bb-plugin-sdk.d.ts",
-      "sha256": "7994e5e3cc8a3f743d1098cb09334201ae359aac5148bd945fb1ac429908c80f"
+      "sha256": "07b1b84f3eea68d78368be93279ed4bf72934e00b17efa26155d5225a1b8d4cc"
     },
     "./ai-services": {
       "types": "bundled-types/bb-plugin-sdk-ai-services.d.ts",
@@ -27,7 +27,7 @@
     },
     "./provider-bridge/testing": {
       "types": "bundled-types/bb-plugin-sdk-provider-bridge-testing.d.ts",
-      "sha256": "c35f7c70cdde2281a6fc5b51a041ea9281f4c232d6a4d730a823cbd5ef8aa8a9"
+      "sha256": "d413ca74e5aa4ea57e826438425172d9fe2175a95f0feaa8a0f52f0d4348048e"
     },
     "./testing": {
       "types": "bundled-types/bb-plugin-sdk-testing.d.ts",
diff --git a/packages/thread-view/src/parse-operation-message.ts b/packages/thread-view/src/parse-operation-message.ts
index ce4a469cab..25077751d6 100644
--- a/packages/thread-view/src/parse-operation-message.ts
+++ b/packages/thread-view/src/parse-operation-message.ts
@@ -127,6 +127,8 @@ function threadInterruptedTitle(reason: SystemThreadInterruptedReason): string {
       return "Stopped manually";
     case "host-daemon-restarted":
       return "Stopped — host daemon restarted";
+    case "host-connection-lost":
+      return "Stopped — connection to host was lost";
     // Legacy persisted watchdog interruption; no current producer.
     case "provider-turn-idle":
       return "Stopped — provider turn stopped responding";
diff --git a/packages/thread-view/test/parse-operation-message.test.ts b/packages/thread-view/test/parse-operation-message.test.ts
index 1d46aab71c..f72f31627c 100644
--- a/packages/thread-view/test/parse-operation-message.test.ts
+++ b/packages/thread-view/test/parse-operation-message.test.ts
@@ -137,6 +137,9 @@ describe("parseOperationMessage operation titles", () => {
       expect(interruptedTitle("host-daemon-restarted", THREAD_NAME)).toBe(
         "Stopped — host daemon restarted",
       );
+      expect(interruptedTitle("host-connection-lost", THREAD_NAME)).toBe(
+        "Stopped — connection to host was lost",
+      );
     });
   });