diff --git a/assistant/src/__tests__/agent-loop-override-profile.test.ts b/assistant/src/__tests__/agent-loop-override-profile.test.ts
index ce36359fd32..5c606cc5f42 100644
--- a/assistant/src/__tests__/agent-loop-override-profile.test.ts
+++ b/assistant/src/__tests__/agent-loop-override-profile.test.ts
@@ -353,6 +353,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   // Always return undefined for the row read so the test fails fast unless
   // executeSubagentSpawn reads from context.overrideProfile first.
   getConversationOverrideProfile: () => undefined,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import { getSubagentManager } from "../subagent/index.js";
diff --git a/assistant/src/__tests__/agent-wake-disk-pressure-callsite.test.ts b/assistant/src/__tests__/agent-wake-disk-pressure-callsite.test.ts
index 7d1147582b7..4694aea641b 100644
--- a/assistant/src/__tests__/agent-wake-disk-pressure-callsite.test.ts
+++ b/assistant/src/__tests__/agent-wake-disk-pressure-callsite.test.ts
@@ -22,6 +22,7 @@ import type { Message } from "../providers/types.js";
 
 mock.module("../memory/conversation-crud.js", () => ({
   getConversationOverrideProfile: () => undefined,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../config/loader.js", () => ({
diff --git a/assistant/src/__tests__/agent-wake-override-profile.test.ts b/assistant/src/__tests__/agent-wake-override-profile.test.ts
index c621456cd74..7e45c46ec59 100644
--- a/assistant/src/__tests__/agent-wake-override-profile.test.ts
+++ b/assistant/src/__tests__/agent-wake-override-profile.test.ts
@@ -32,6 +32,7 @@ let mockOverrideProfile: string | undefined = undefined;
 
 mock.module("../memory/conversation-crud.js", () => ({
   getConversationOverrideProfile: (_id: string) => mockOverrideProfile,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Mutable stub for `getConfig().llm` consumed by `RetryProvider`'s
diff --git a/assistant/src/__tests__/annotate-risk-options.test.ts b/assistant/src/__tests__/annotate-risk-options.test.ts
index 92fcb61c3a9..97c62ac21fe 100644
--- a/assistant/src/__tests__/annotate-risk-options.test.ts
+++ b/assistant/src/__tests__/annotate-risk-options.test.ts
@@ -57,6 +57,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     updates.push({ id, content });
   },
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/__tests__/approval-cascade.test.ts b/assistant/src/__tests__/approval-cascade.test.ts
index 24fd5d743f8..700762339b6 100644
--- a/assistant/src/__tests__/approval-cascade.test.ts
+++ b/assistant/src/__tests__/approval-cascade.test.ts
@@ -151,6 +151,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   addMessage: () => ({ id: `msg-${Date.now()}` }),
   updateConversationUsage: () => {},
   updateConversationTitle: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/background-workers-disk-pressure.test.ts b/assistant/src/__tests__/background-workers-disk-pressure.test.ts
index 0565bed61a3..4188ed39cf0 100644
--- a/assistant/src/__tests__/background-workers-disk-pressure.test.ts
+++ b/assistant/src/__tests__/background-workers-disk-pressure.test.ts
@@ -152,6 +152,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setLastNotifiedInferenceProfile: mock(() => {}),
   setConversationHistoryStrippedAt: mock(() => {}),
   wipeConversation: mock(() => ({ memoryIds: [] })),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-title-service.js", () => ({
diff --git a/assistant/src/__tests__/btw-routes.test.ts b/assistant/src/__tests__/btw-routes.test.ts
index db2e9b8951d..9e3770fce20 100644
--- a/assistant/src/__tests__/btw-routes.test.ts
+++ b/assistant/src/__tests__/btw-routes.test.ts
@@ -38,6 +38,7 @@ const mockAddMessage = mock(() => {});
 
 mock.module("../memory/conversation-crud.js", () => ({
   addMessage: mockAddMessage,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const MOCK_TOOLS = [
diff --git a/assistant/src/__tests__/channel-reply-delivery.test.ts b/assistant/src/__tests__/channel-reply-delivery.test.ts
index 2f7b20970f8..c0d95053a96 100644
--- a/assistant/src/__tests__/channel-reply-delivery.test.ts
+++ b/assistant/src/__tests__/channel-reply-delivery.test.ts
@@ -128,6 +128,7 @@ mock.module("../memory/conversation-crud.js", () => ({
         : {};
     row.metadata = JSON.stringify({ ...existing, ...updates });
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/attachments-store.js", () => ({
diff --git a/assistant/src/__tests__/compaction-events.test.ts b/assistant/src/__tests__/compaction-events.test.ts
index f90dc06f02e..d5ab0a8312b 100644
--- a/assistant/src/__tests__/compaction-events.test.ts
+++ b/assistant/src/__tests__/compaction-events.test.ts
@@ -150,6 +150,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   addMessage: () => ({ id: `msg-${Date.now()}` }),
   updateConversationUsage: () => {},
   updateConversationTitle: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/compactor-call-site-logging.test.ts b/assistant/src/__tests__/compactor-call-site-logging.test.ts
index 03fb7d6f7bb..63066b5e97f 100644
--- a/assistant/src/__tests__/compactor-call-site-logging.test.ts
+++ b/assistant/src/__tests__/compactor-call-site-logging.test.ts
@@ -31,6 +31,7 @@ mock.module("../util/logger.js", () => ({
 
 mock.module("../memory/conversation-crud.js", () => ({
   getMessages: () => [],
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/attachments-store.js", () => ({
diff --git a/assistant/src/__tests__/compactor-preserved-tail-count.test.ts b/assistant/src/__tests__/compactor-preserved-tail-count.test.ts
index d0797418a55..00973e6d69c 100644
--- a/assistant/src/__tests__/compactor-preserved-tail-count.test.ts
+++ b/assistant/src/__tests__/compactor-preserved-tail-count.test.ts
@@ -23,6 +23,7 @@ mock.module("../util/logger.js", () => ({
 
 mock.module("../memory/conversation-crud.js", () => ({
   getMessages: () => [],
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/attachments-store.js", () => ({
diff --git a/assistant/src/__tests__/conversation-abort-tool-results.test.ts b/assistant/src/__tests__/conversation-abort-tool-results.test.ts
index ec9bfc5546c..642f955bfa4 100644
--- a/assistant/src/__tests__/conversation-abort-tool-results.test.ts
+++ b/assistant/src/__tests__/conversation-abort-tool-results.test.ts
@@ -138,6 +138,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationTitle: () => {},
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-agent-loop-disk-pressure.test.ts b/assistant/src/__tests__/conversation-agent-loop-disk-pressure.test.ts
index 0110037d4d9..cf1e1c860c1 100644
--- a/assistant/src/__tests__/conversation-agent-loop-disk-pressure.test.ts
+++ b/assistant/src/__tests__/conversation-agent-loop-disk-pressure.test.ts
@@ -100,6 +100,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setConversationHistoryStrippedAt: () => {},
   updateConversationContextWindow: () => {},
   updateConversationSlackContextWatermark: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import { runAgentLoopImpl } from "../daemon/conversation-agent-loop.js";
diff --git a/assistant/src/__tests__/conversation-agent-loop-inference-profile.test.ts b/assistant/src/__tests__/conversation-agent-loop-inference-profile.test.ts
index 9d4b57bfdd8..3f0d94e2c26 100644
--- a/assistant/src/__tests__/conversation-agent-loop-inference-profile.test.ts
+++ b/assistant/src/__tests__/conversation-agent-loop-inference-profile.test.ts
@@ -170,6 +170,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
   setLastNotifiedInferenceProfile: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/conversation-agent-loop-overflow.test.ts b/assistant/src/__tests__/conversation-agent-loop-overflow.test.ts
index 8d5f98d321e..cba8d6d93b6 100644
--- a/assistant/src/__tests__/conversation-agent-loop-overflow.test.ts
+++ b/assistant/src/__tests__/conversation-agent-loop-overflow.test.ts
@@ -198,6 +198,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setLastNotifiedInferenceProfile: () => {},
   getLastUserTimestampBefore: () => 0,
   getConversationOverrideProfileFromRow: () => undefined,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 afterAll(() => {
diff --git a/assistant/src/__tests__/conversation-agent-loop.test.ts b/assistant/src/__tests__/conversation-agent-loop.test.ts
index 9289f660442..6afebd292f8 100644
--- a/assistant/src/__tests__/conversation-agent-loop.test.ts
+++ b/assistant/src/__tests__/conversation-agent-loop.test.ts
@@ -197,6 +197,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getConversationOriginChannel: () => null,
   getMessageById: () => mockMessageById,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 afterAll(() => {
diff --git a/assistant/src/__tests__/conversation-analysis-routes.test.ts b/assistant/src/__tests__/conversation-analysis-routes.test.ts
index 74d900108a5..8efd0108a6d 100644
--- a/assistant/src/__tests__/conversation-analysis-routes.test.ts
+++ b/assistant/src/__tests__/conversation-analysis-routes.test.ts
@@ -26,6 +26,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessages: mockGetMessages,
   createConversation: mockCreateConversation,
   addMessage: mockAddMessage,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../export/transcript-formatter.js", () => ({
diff --git a/assistant/src/__tests__/conversation-app-control-lifecycle.test.ts b/assistant/src/__tests__/conversation-app-control-lifecycle.test.ts
index 431e71b6d90..29612fcd4a9 100644
--- a/assistant/src/__tests__/conversation-app-control-lifecycle.test.ts
+++ b/assistant/src/__tests__/conversation-app-control-lifecycle.test.ts
@@ -92,6 +92,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   addMessage: async () => ({ id: "persisted-1" }),
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-confirmation-signals.test.ts b/assistant/src/__tests__/conversation-confirmation-signals.test.ts
index 3064ebeda27..3298fd11211 100644
--- a/assistant/src/__tests__/conversation-confirmation-signals.test.ts
+++ b/assistant/src/__tests__/conversation-confirmation-signals.test.ts
@@ -142,6 +142,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   addMessage: () => ({ id: `msg-${Date.now()}` }),
   updateConversationUsage: () => {},
   updateConversationTitle: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-history-web-search.test.ts b/assistant/src/__tests__/conversation-history-web-search.test.ts
index 1bf412e9875..f52fe4ea9b1 100644
--- a/assistant/src/__tests__/conversation-history-web-search.test.ts
+++ b/assistant/src/__tests__/conversation-history-web-search.test.ts
@@ -50,6 +50,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   },
   relinkAttachments: () => 0,
   deleteLastExchange: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-lifecycle.test.ts b/assistant/src/__tests__/conversation-lifecycle.test.ts
index 65e3e8438a5..7777035b410 100644
--- a/assistant/src/__tests__/conversation-lifecycle.test.ts
+++ b/assistant/src/__tests__/conversation-lifecycle.test.ts
@@ -102,6 +102,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   },
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-load-history-repair.test.ts b/assistant/src/__tests__/conversation-load-history-repair.test.ts
index 226403d86ba..11fef5c1652 100644
--- a/assistant/src/__tests__/conversation-load-history-repair.test.ts
+++ b/assistant/src/__tests__/conversation-load-history-repair.test.ts
@@ -104,6 +104,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   },
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-load-history-stripped.test.ts b/assistant/src/__tests__/conversation-load-history-stripped.test.ts
index 3911c31c382..1b886cf874b 100644
--- a/assistant/src/__tests__/conversation-load-history-stripped.test.ts
+++ b/assistant/src/__tests__/conversation-load-history-stripped.test.ts
@@ -87,6 +87,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setConversationHistoryStrippedAt: () => {},
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-pairing.test.ts b/assistant/src/__tests__/conversation-pairing.test.ts
index 2cdadcb1e4e..e5f0298c99f 100644
--- a/assistant/src/__tests__/conversation-pairing.test.ts
+++ b/assistant/src/__tests__/conversation-pairing.test.ts
@@ -67,6 +67,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   createConversation: createConversationMock,
   addMessage: addMessageMock,
   getConversation: getConversationMock,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 /** Simulated bindings for external-conversation-store mock. */
diff --git a/assistant/src/__tests__/conversation-process-app-control-preactivation.test.ts b/assistant/src/__tests__/conversation-process-app-control-preactivation.test.ts
index b451dc99c9d..4be45ffc4ec 100644
--- a/assistant/src/__tests__/conversation-process-app-control-preactivation.test.ts
+++ b/assistant/src/__tests__/conversation-process-app-control-preactivation.test.ts
@@ -50,6 +50,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     trustContext: undefined,
   }),
   addMessage: () => ({ id: "msg-mock" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/canonical-guardian-store.js", () => ({
diff --git a/assistant/src/__tests__/conversation-process-callsite.test.ts b/assistant/src/__tests__/conversation-process-callsite.test.ts
index ae0f7033757..f82c1e32434 100644
--- a/assistant/src/__tests__/conversation-process-callsite.test.ts
+++ b/assistant/src/__tests__/conversation-process-callsite.test.ts
@@ -183,6 +183,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationTitle: () => {},
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-provider-retry-repair.test.ts b/assistant/src/__tests__/conversation-provider-retry-repair.test.ts
index d7609b5206e..286d0de9b0c 100644
--- a/assistant/src/__tests__/conversation-provider-retry-repair.test.ts
+++ b/assistant/src/__tests__/conversation-provider-retry-repair.test.ts
@@ -185,6 +185,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => ({}),
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-queue.test.ts b/assistant/src/__tests__/conversation-queue.test.ts
index d256eef9b7b..f62da7d1082 100644
--- a/assistant/src/__tests__/conversation-queue.test.ts
+++ b/assistant/src/__tests__/conversation-queue.test.ts
@@ -193,6 +193,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationTitle: () => {},
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-routes-guardian-reply.test.ts b/assistant/src/__tests__/conversation-routes-guardian-reply.test.ts
index c337c9dec27..049420bded8 100644
--- a/assistant/src/__tests__/conversation-routes-guardian-reply.test.ts
+++ b/assistant/src/__tests__/conversation-routes-guardian-reply.test.ts
@@ -83,6 +83,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     content: string,
     metadata?: Record<string, unknown>,
   ) => addMessageMock(conversationId, role, content, metadata),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../runtime/local-actor-identity.js", () => ({
diff --git a/assistant/src/__tests__/conversation-routes-slash-commands.test.ts b/assistant/src/__tests__/conversation-routes-slash-commands.test.ts
index cf3295591c5..0eda843653e 100644
--- a/assistant/src/__tests__/conversation-routes-slash-commands.test.ts
+++ b/assistant/src/__tests__/conversation-routes-slash-commands.test.ts
@@ -139,6 +139,7 @@ mock.module("../memory/conversation-crud.js", () => ({
       : { provenanceTrustClass: "unknown" },
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../daemon/conversation-process.js", () => ({
diff --git a/assistant/src/__tests__/conversation-slash-queue.test.ts b/assistant/src/__tests__/conversation-slash-queue.test.ts
index ed87b181d5f..ae319f04609 100644
--- a/assistant/src/__tests__/conversation-slash-queue.test.ts
+++ b/assistant/src/__tests__/conversation-slash-queue.test.ts
@@ -135,6 +135,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationTitle: () => {},
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-slash-unknown.test.ts b/assistant/src/__tests__/conversation-slash-unknown.test.ts
index f7abadda9bd..098f6174810 100644
--- a/assistant/src/__tests__/conversation-slash-unknown.test.ts
+++ b/assistant/src/__tests__/conversation-slash-unknown.test.ts
@@ -136,6 +136,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationTitle: () => {},
   getMessageById: () => null,
   getLastUserTimestampBefore: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-speed-override.test.ts b/assistant/src/__tests__/conversation-speed-override.test.ts
index 6b540ed8e49..9e2be67b41b 100644
--- a/assistant/src/__tests__/conversation-speed-override.test.ts
+++ b/assistant/src/__tests__/conversation-speed-override.test.ts
@@ -150,6 +150,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   addMessage: () => ({ id: `msg-${Date.now()}` }),
   updateConversationUsage: () => {},
   updateConversationTitle: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-surfaces-data-persist.test.ts b/assistant/src/__tests__/conversation-surfaces-data-persist.test.ts
index 752501269a9..4f2055dc2e0 100644
--- a/assistant/src/__tests__/conversation-surfaces-data-persist.test.ts
+++ b/assistant/src/__tests__/conversation-surfaces-data-persist.test.ts
@@ -29,6 +29,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessages: (conversationId: string) => getMessagesImpl(conversationId),
   updateMessageContent: (id: string, content: string) =>
     updateMessageContentSpy(id, content),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Imports must come AFTER mock.module so the surface module picks up
diff --git a/assistant/src/__tests__/conversation-title-service.test.ts b/assistant/src/__tests__/conversation-title-service.test.ts
index 93213b8b8f3..2a4d9057df9 100644
--- a/assistant/src/__tests__/conversation-title-service.test.ts
+++ b/assistant/src/__tests__/conversation-title-service.test.ts
@@ -37,6 +37,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getConversation: mockGetConversation,
   getMessages: mockGetMessages,
   updateConversationTitle: mockUpdateConversationTitle,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../providers/provider-send-message.js", () => ({
diff --git a/assistant/src/__tests__/conversation-usage.test.ts b/assistant/src/__tests__/conversation-usage.test.ts
index e8c9cbf1bdc..17b296282ef 100644
--- a/assistant/src/__tests__/conversation-usage.test.ts
+++ b/assistant/src/__tests__/conversation-usage.test.ts
@@ -36,6 +36,7 @@ mock.module("../memory/conversation-crud.js", () => ({
       estimatedCost,
     });
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import { recordUsage } from "../daemon/conversation-usage.js";
diff --git a/assistant/src/__tests__/conversation-workspace-cache-state.test.ts b/assistant/src/__tests__/conversation-workspace-cache-state.test.ts
index 9a330d17437..ffc4a2e43f7 100644
--- a/assistant/src/__tests__/conversation-workspace-cache-state.test.ts
+++ b/assistant/src/__tests__/conversation-workspace-cache-state.test.ts
@@ -111,6 +111,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateConversationContextWindow: () => {},
   deleteMessageById: () => ({ segmentIds: [], deletedSummaryIds: [] }),
   deleteLastExchange: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-workspace-injection.test.ts b/assistant/src/__tests__/conversation-workspace-injection.test.ts
index 6c73cb4a4a1..c1ccac68ad2 100644
--- a/assistant/src/__tests__/conversation-workspace-injection.test.ts
+++ b/assistant/src/__tests__/conversation-workspace-injection.test.ts
@@ -145,6 +145,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setLastNotifiedInferenceProfile: () => {},
   getConversationOverrideProfileFromRow: () => undefined,
   updateMessageMetadata: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/conversation-workspace-tool-tracking.test.ts b/assistant/src/__tests__/conversation-workspace-tool-tracking.test.ts
index 72c7402347c..17b01ce7f4c 100644
--- a/assistant/src/__tests__/conversation-workspace-tool-tracking.test.ts
+++ b/assistant/src/__tests__/conversation-workspace-tool-tracking.test.ts
@@ -142,6 +142,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   setLastNotifiedInferenceProfile: () => {},
   getConversationOverrideProfileFromRow: () => undefined,
   updateMessageMetadata: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/dm-persistence.test.ts b/assistant/src/__tests__/dm-persistence.test.ts
index 7909fcf5d77..739d6d759f1 100644
--- a/assistant/src/__tests__/dm-persistence.test.ts
+++ b/assistant/src/__tests__/dm-persistence.test.ts
@@ -43,6 +43,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => ({}),
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/filing-service.test.ts b/assistant/src/__tests__/filing-service.test.ts
index ea2d9bbfc4b..2ed0ee1e63c 100644
--- a/assistant/src/__tests__/filing-service.test.ts
+++ b/assistant/src/__tests__/filing-service.test.ts
@@ -83,6 +83,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     createdConversations.push(opts);
     return { id: `conv-${++conversationIdCounter}`, ...opts };
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Mock logger
diff --git a/assistant/src/__tests__/handlers-user-message-approval-consumption.test.ts b/assistant/src/__tests__/handlers-user-message-approval-consumption.test.ts
index 8621c0c2441..f98e9048ccd 100644
--- a/assistant/src/__tests__/handlers-user-message-approval-consumption.test.ts
+++ b/assistant/src/__tests__/handlers-user-message-approval-consumption.test.ts
@@ -92,6 +92,7 @@ mock.module("../runtime/pending-interactions.js", () => ({
 
 mock.module("../memory/conversation-crud.js", () => ({
   addMessage: mock(async () => ({ id: "persisted-message-id" })),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../config/loader.js", () => ({
diff --git a/assistant/src/__tests__/heartbeat-disk-pressure.test.ts b/assistant/src/__tests__/heartbeat-disk-pressure.test.ts
index 117e700abcf..fe7d8ac41e9 100644
--- a/assistant/src/__tests__/heartbeat-disk-pressure.test.ts
+++ b/assistant/src/__tests__/heartbeat-disk-pressure.test.ts
@@ -74,6 +74,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   // addMessage. Disk-pressure short-circuits before addMessage ever runs,
   // but the mock module must still expose every name the real module does.
   addMessage: () => Promise.resolve({ id: "mock-msg-id" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const mockProcessMessage = mock(() => Promise.resolve({ messageId: "msg-1" }));
diff --git a/assistant/src/__tests__/heartbeat-service.test.ts b/assistant/src/__tests__/heartbeat-service.test.ts
index 9e002a8e74c..163b55535e5 100644
--- a/assistant/src/__tests__/heartbeat-service.test.ts
+++ b/assistant/src/__tests__/heartbeat-service.test.ts
@@ -159,6 +159,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     createdConversations.push(opts);
     return { id: `conv-${++conversationIdCounter}`, ...opts };
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Mock logger — capture warn calls for unreachable-credential assertions
diff --git a/assistant/src/__tests__/http-user-message-parity.test.ts b/assistant/src/__tests__/http-user-message-parity.test.ts
index 1ce80d5ef77..ae63979da36 100644
--- a/assistant/src/__tests__/http-user-message-parity.test.ts
+++ b/assistant/src/__tests__/http-user-message-parity.test.ts
@@ -100,6 +100,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     content: string,
     metadata?: Record<string, unknown>,
   ) => addMessageMock(conversationId, role, content, metadata),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../runtime/local-actor-identity.js", () => ({
diff --git a/assistant/src/__tests__/inbound-slack-persistence.test.ts b/assistant/src/__tests__/inbound-slack-persistence.test.ts
index 941e01adace..aec90d61ded 100644
--- a/assistant/src/__tests__/inbound-slack-persistence.test.ts
+++ b/assistant/src/__tests__/inbound-slack-persistence.test.ts
@@ -48,6 +48,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => ({}),
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/messaging-send-tool.test.ts b/assistant/src/__tests__/messaging-send-tool.test.ts
index 3d6c18a2759..3c8d76fadf6 100644
--- a/assistant/src/__tests__/messaging-send-tool.test.ts
+++ b/assistant/src/__tests__/messaging-send-tool.test.ts
@@ -79,6 +79,7 @@ const getBindingByChannelChatMock = mock(
 mock.module("../memory/conversation-crud.js", () => ({
   addMessage: addMessageMock,
   getConversation: getConversationMock,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/outbound-slack-persistence.test.ts b/assistant/src/__tests__/outbound-slack-persistence.test.ts
index 34b785ab1e6..89c25f0cdc5 100644
--- a/assistant/src/__tests__/outbound-slack-persistence.test.ts
+++ b/assistant/src/__tests__/outbound-slack-persistence.test.ts
@@ -111,6 +111,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   // The handler treats provenance as a flat spread; returning {} keeps the
   // metadata snapshot focused on the fields under test.
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/__tests__/persistence-pipeline.test.ts b/assistant/src/__tests__/persistence-pipeline.test.ts
index c08cae06a08..ac6d5699c72 100644
--- a/assistant/src/__tests__/persistence-pipeline.test.ts
+++ b/assistant/src/__tests__/persistence-pipeline.test.ts
@@ -25,6 +25,8 @@ import {
   createConversation,
   getMessageById,
   getMessages,
+  reserveMessage,
+  updateMessageContent,
   updateMessageMetadata,
 } from "../memory/conversation-crud.js";
 import { getDb } from "../memory/db-connection.js";
@@ -44,6 +46,7 @@ import type {
   PersistAddResult,
   PersistArgs,
   PersistDeleteResult,
+  PersistReserveResult,
   PersistResult,
   Plugin,
   TurnContext,
@@ -215,6 +218,80 @@ describe("persistence pipeline", () => {
     expect(getMessages(conv.id)).toHaveLength(0);
   });
 
+  test("default plugin: reserve op pre-allocates an empty assistant row", async () => {
+    registerPlugin(defaultPersistencePlugin);
+
+    const conv = createConversation();
+
+    const result = (await runPipeline<PersistArgs, PersistResult>(
+      "persistence",
+      getMiddlewaresFor("persistence"),
+      defaultPersistenceTerminal,
+      {
+        op: "reserve",
+        conversationId: conv.id,
+        role: "assistant",
+        metadata: { reservedFor: "anchor" },
+      },
+      makeCtx({ conversationId: conv.id }),
+      DEFAULT_TIMEOUTS.persistence,
+    )) as PersistReserveResult;
+
+    expect(result.op).toBe("reserve");
+    expect(result.message.id).toBeTruthy();
+    expect(result.message.role).toBe("assistant");
+    // Reserve places an empty JSON array so consumers that parse content
+    // observe a no-content payload.
+    expect(result.message.content).toBe("[]");
+
+    // Row must exist with the expected shape and live in the conversation.
+    const row = getMessageById(result.message.id, conv.id);
+    expect(row).not.toBeNull();
+    expect(row?.content).toBe("[]");
+    expect(JSON.parse(row!.metadata!)).toEqual({ reservedFor: "anchor" });
+    expect(getMessages(conv.id).map((m) => m.id)).toContain(result.message.id);
+  });
+
+  test("default plugin: updateContent op overwrites an existing row's content", async () => {
+    registerPlugin(defaultPersistencePlugin);
+
+    const conv = createConversation();
+
+    // Reserve first, then overwrite — exactly the B3 sequence consumers will
+    // follow.
+    const reserved = await reserveMessage(conv.id, "assistant");
+    expect(getMessageById(reserved.id, conv.id)?.content).toBe("[]");
+
+    const result = await runPipeline<PersistArgs, PersistResult>(
+      "persistence",
+      getMiddlewaresFor("persistence"),
+      defaultPersistenceTerminal,
+      {
+        op: "updateContent",
+        messageId: reserved.id,
+        content: JSON.stringify([{ type: "text", text: "Hello" }]),
+      },
+      makeCtx({ conversationId: conv.id }),
+      DEFAULT_TIMEOUTS.persistence,
+    );
+    expect(result).toEqual({ op: "updateContent" });
+
+    // Content updated in place; row id unchanged.
+    const row = getMessageById(reserved.id, conv.id);
+    expect(row).not.toBeNull();
+    expect(JSON.parse(row!.content)).toEqual([{ type: "text", text: "Hello" }]);
+
+    // Direct-call parity: a fresh reserve + direct updateMessageContent
+    // should land the same content shape.
+    const baselineReserved = await reserveMessage(conv.id, "assistant");
+    updateMessageContent(
+      baselineReserved.id,
+      JSON.stringify([{ type: "text", text: "Hello" }]),
+    );
+    const baselineRow = getMessageById(baselineReserved.id, conv.id);
+    expect(baselineRow?.content).toBe(row?.content);
+  });
+
   test("custom plugin: short-circuits every op onto a mock in-memory store", async () => {
     type Stored = {
       id: string;
@@ -249,6 +326,33 @@ describe("persistence pipeline", () => {
               },
             };
           }
+          case "reserve": {
+            const id = `mock-${nextId++}`;
+            mockStore.set(id, {
+              id,
+              conversationId: args.conversationId,
+              role: args.role,
+              content: "[]",
+              metadata: { ...(args.metadata ?? {}) },
+            });
+            return {
+              op: "reserve",
+              message: {
+                id,
+                conversationId: args.conversationId,
+                role: args.role,
+                content: "[]",
+                createdAt: 123,
+              },
+            };
+          }
+          case "updateContent": {
+            const existing = mockStore.get(args.messageId);
+            if (existing) {
+              existing.content = args.content;
+            }
+            return { op: "updateContent" };
+          }
           case "update": {
             const existing = mockStore.get(args.messageId);
             if (existing) {
@@ -298,6 +402,40 @@ describe("persistence pipeline", () => {
     expect(addResult.message.id).toBe("mock-1");
     expect(mockStore.size).toBe(1);
 
+    const reserveResult = (await runPipeline<PersistArgs, PersistResult>(
+      "persistence",
+      getMiddlewaresFor("persistence"),
+      defaultPersistenceTerminal,
+      {
+        op: "reserve",
+        conversationId: conv.id,
+        role: "assistant",
+        metadata: { reservedFor: "mock-anchor" },
+      },
+      makeCtx({ conversationId: conv.id }),
+      DEFAULT_TIMEOUTS.persistence,
+    )) as PersistReserveResult;
+    expect(reserveResult.op).toBe("reserve");
+    expect(reserveResult.message.id).toBe("mock-2");
+    expect(reserveResult.message.content).toBe("[]");
+    expect(mockStore.get("mock-2")?.content).toBe("[]");
+
+    await runPipeline<PersistArgs, PersistResult>(
+      "persistence",
+      getMiddlewaresFor("persistence"),
+      defaultPersistenceTerminal,
+      {
+        op: "updateContent",
+        messageId: "mock-2",
+        content: '[{"type":"text","text":"finalized"}]',
+      },
+      makeCtx({ conversationId: conv.id }),
+      DEFAULT_TIMEOUTS.persistence,
+    );
+    expect(mockStore.get("mock-2")?.content).toBe(
+      '[{"type":"text","text":"finalized"}]',
+    );
+
     await runPipeline<PersistArgs, PersistResult>(
       "persistence",
       getMiddlewaresFor("persistence"),
@@ -326,7 +464,7 @@ describe("persistence pipeline", () => {
     expect(delResult.op).toBe("delete");
     expect(mockStore.has("mock-1")).toBe(false);
 
-    // The real DB must not have been touched by any of the three ops.
+    // The real DB must not have been touched by any of the ops.
     expect(getMessages(conv.id)).toHaveLength(dbRowsBefore);
   });
 
diff --git a/assistant/src/__tests__/persistence-secret-redaction.test.ts b/assistant/src/__tests__/persistence-secret-redaction.test.ts
index db89d33a76e..ce926835754 100644
--- a/assistant/src/__tests__/persistence-secret-redaction.test.ts
+++ b/assistant/src/__tests__/persistence-secret-redaction.test.ts
@@ -60,6 +60,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   updateMessageContent: () => {},
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/__tests__/process-message-background-slack.test.ts b/assistant/src/__tests__/process-message-background-slack.test.ts
index 1aefaef0e73..df96189b48a 100644
--- a/assistant/src/__tests__/process-message-background-slack.test.ts
+++ b/assistant/src/__tests__/process-message-background-slack.test.ts
@@ -24,6 +24,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => ({}),
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/process-message-display-content.test.ts b/assistant/src/__tests__/process-message-display-content.test.ts
index 94cb38b1b7d..fe0aa426321 100644
--- a/assistant/src/__tests__/process-message-display-content.test.ts
+++ b/assistant/src/__tests__/process-message-display-content.test.ts
@@ -50,6 +50,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => ({}),
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-disk-view.js", () => ({
diff --git a/assistant/src/__tests__/recording-handler.test.ts b/assistant/src/__tests__/recording-handler.test.ts
index 1dcef3dd46a..548c69a829c 100644
--- a/assistant/src/__tests__/recording-handler.test.ts
+++ b/assistant/src/__tests__/recording-handler.test.ts
@@ -68,6 +68,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   },
   createConversation: () => ({ id: "conv-mock" }),
   getConversation: () => ({ id: "conv-mock" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Attachments store mock
diff --git a/assistant/src/__tests__/regenerate-fire-and-forget-trace.test.ts b/assistant/src/__tests__/regenerate-fire-and-forget-trace.test.ts
index ca8068240eb..d03b2b622c7 100644
--- a/assistant/src/__tests__/regenerate-fire-and-forget-trace.test.ts
+++ b/assistant/src/__tests__/regenerate-fire-and-forget-trace.test.ts
@@ -32,6 +32,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   updateMessageContent: () => {},
   relinkAttachments: () => 0,
   deleteLastExchange: () => 0,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/conversation-queries.js", () => ({
diff --git a/assistant/src/__tests__/secret-ingress-http.test.ts b/assistant/src/__tests__/secret-ingress-http.test.ts
index 17c8af3a6c6..c4f8f8bf3d5 100644
--- a/assistant/src/__tests__/secret-ingress-http.test.ts
+++ b/assistant/src/__tests__/secret-ingress-http.test.ts
@@ -106,6 +106,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   provenanceFromTrustContext: () => undefined,
   setConversationOriginChannelIfUnset: () => {},
   setConversationOriginInterfaceIfUnset: () => {},
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../runtime/local-actor-identity.js", () => ({
diff --git a/assistant/src/__tests__/subagent-notify-parent.test.ts b/assistant/src/__tests__/subagent-notify-parent.test.ts
index 7acdcbb4d2b..64bdbb24396 100644
--- a/assistant/src/__tests__/subagent-notify-parent.test.ts
+++ b/assistant/src/__tests__/subagent-notify-parent.test.ts
@@ -27,6 +27,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getConversationOriginChannel: () => null,
   getMessages: () => null,
   createConversation: () => ({ id: "mock-conv" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 /**
diff --git a/assistant/src/__tests__/subagent-spawn-tool-fork.test.ts b/assistant/src/__tests__/subagent-spawn-tool-fork.test.ts
index 77a3c0f8703..85f4230a40d 100644
--- a/assistant/src/__tests__/subagent-spawn-tool-fork.test.ts
+++ b/assistant/src/__tests__/subagent-spawn-tool-fork.test.ts
@@ -26,6 +26,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getConversationOriginChannel: () => null,
   getMessages: () => null,
   createConversation: () => ({ id: "mock-conv" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import {
diff --git a/assistant/src/__tests__/subagent-tools.test.ts b/assistant/src/__tests__/subagent-tools.test.ts
index 255df572a71..cbc3bd1e32c 100644
--- a/assistant/src/__tests__/subagent-tools.test.ts
+++ b/assistant/src/__tests__/subagent-tools.test.ts
@@ -30,6 +30,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getConversationOriginChannel: () => null,
   getMessages: (conversationId: string) => mockGetMessages(conversationId),
   createConversation: () => ({ id: "mock-conv" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import { getSubagentManager } from "../subagent/index.js";
diff --git a/assistant/src/__tests__/suggestion-routes.test.ts b/assistant/src/__tests__/suggestion-routes.test.ts
index 9d0e1325a10..38a41ad7cca 100644
--- a/assistant/src/__tests__/suggestion-routes.test.ts
+++ b/assistant/src/__tests__/suggestion-routes.test.ts
@@ -52,6 +52,7 @@ const mockGetMessages = mock((_conversationId: string) => [
 mock.module("../memory/conversation-crud.js", () => ({
   getMessages: mockGetMessages,
   getConversation: (_id: string) => null,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const mockGetConfiguredProvider = mock(async () => ({
diff --git a/assistant/src/__tests__/tool-executor-lifecycle-events.test.ts b/assistant/src/__tests__/tool-executor-lifecycle-events.test.ts
index fca0c9213c3..a85facfd4c7 100644
--- a/assistant/src/__tests__/tool-executor-lifecycle-events.test.ts
+++ b/assistant/src/__tests__/tool-executor-lifecycle-events.test.ts
@@ -72,6 +72,7 @@ mock.module("../permissions/checker.js", () => ({
 
 mock.module("../memory/conversation-crud.js", () => ({
   createConversation: (title: string) => ({ id: "conversation-1", title }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Mock every export so downstream test files that dynamically import modules
diff --git a/assistant/src/__tests__/tool-preview-lifecycle.test.ts b/assistant/src/__tests__/tool-preview-lifecycle.test.ts
index 7e07d9c3552..514bba9cb73 100644
--- a/assistant/src/__tests__/tool-preview-lifecycle.test.ts
+++ b/assistant/src/__tests__/tool-preview-lifecycle.test.ts
@@ -45,6 +45,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   updateMessageContent: () => {},
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/__tests__/tool-result-metadata-plumbing.test.ts b/assistant/src/__tests__/tool-result-metadata-plumbing.test.ts
index e2f3c1d5bfa..19aaa5ea87c 100644
--- a/assistant/src/__tests__/tool-result-metadata-plumbing.test.ts
+++ b/assistant/src/__tests__/tool-result-metadata-plumbing.test.ts
@@ -44,6 +44,7 @@ mock.module("../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   updateMessageContent: () => {},
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/__tests__/verification-control-plane-policy.test.ts b/assistant/src/__tests__/verification-control-plane-policy.test.ts
index fc53ebf65a7..f06d6c2ee9a 100644
--- a/assistant/src/__tests__/verification-control-plane-policy.test.ts
+++ b/assistant/src/__tests__/verification-control-plane-policy.test.ts
@@ -73,6 +73,7 @@ mock.module("../permissions/checker.js", () => ({
 
 mock.module("../memory/conversation-crud.js", () => ({
   createConversation: (title: string) => ({ id: "conversation-1", title }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Mock every export so downstream test files that dynamically import modules
diff --git a/assistant/src/daemon/__tests__/conversation-surfaces-launch.test.ts b/assistant/src/daemon/__tests__/conversation-surfaces-launch.test.ts
index d3c2b1bf7c4..98314a60931 100644
--- a/assistant/src/daemon/__tests__/conversation-surfaces-launch.test.ts
+++ b/assistant/src/daemon/__tests__/conversation-surfaces-launch.test.ts
@@ -73,6 +73,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
   ) => {
     updateTitleCalls.push({ conversationId, title });
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Stub conversation-store so the real `launchConversation` can hydrate
diff --git a/assistant/src/daemon/__tests__/daemon-skill-host.test.ts b/assistant/src/daemon/__tests__/daemon-skill-host.test.ts
index 6ef1c89a011..dc2667f3d84 100644
--- a/assistant/src/daemon/__tests__/daemon-skill-host.test.ts
+++ b/assistant/src/daemon/__tests__/daemon-skill-host.test.ts
@@ -95,6 +95,7 @@ mock.module("../../security/secure-keys.js", () => ({
 
 mock.module("../../memory/conversation-crud.js", () => ({
   addMessage: async () => ({ id: "msg-123" }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../runtime/agent-wake.js", () => ({
diff --git a/assistant/src/daemon/__tests__/native-web-search-metadata.test.ts b/assistant/src/daemon/__tests__/native-web-search-metadata.test.ts
index 3d51268edb1..204b7b0ccfb 100644
--- a/assistant/src/daemon/__tests__/native-web-search-metadata.test.ts
+++ b/assistant/src/daemon/__tests__/native-web-search-metadata.test.ts
@@ -42,6 +42,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   updateMessageContent: () => {},
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/daemon/__tests__/web-search-status-text.test.ts b/assistant/src/daemon/__tests__/web-search-status-text.test.ts
index 9beb2e177fe..f7673a3d3f8 100644
--- a/assistant/src/daemon/__tests__/web-search-status-text.test.ts
+++ b/assistant/src/daemon/__tests__/web-search-status-text.test.ts
@@ -40,6 +40,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
   getMessageById: () => null,
   updateMessageContent: () => {},
   provenanceFromTrustContext: () => ({}),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../memory/llm-request-log-store.js", () => ({
diff --git a/assistant/src/export/__tests__/transcript-formatter.test.ts b/assistant/src/export/__tests__/transcript-formatter.test.ts
index 1362c2bd1e5..bb1a7acd003 100644
--- a/assistant/src/export/__tests__/transcript-formatter.test.ts
+++ b/assistant/src/export/__tests__/transcript-formatter.test.ts
@@ -76,6 +76,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
   getMessages: (id: string) =>
     id === "child-conv-1" ? childMessages : parentMessages,
   messageMetadataSchema,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../util/truncate.js", () => ({
diff --git a/assistant/src/ipc/__tests__/cli-ipc.test.ts b/assistant/src/ipc/__tests__/cli-ipc.test.ts
index 65dd23ddc0c..f34759bf6c3 100644
--- a/assistant/src/ipc/__tests__/cli-ipc.test.ts
+++ b/assistant/src/ipc/__tests__/cli-ipc.test.ts
@@ -37,6 +37,7 @@ mock.module("../../runtime/agent-wake.js", () => ({
 
 mock.module("../../memory/conversation-crud.js", () => ({
   getConversation: (id: string) => ({ id, createdAt: Date.now() }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // ---------------------------------------------------------------------------
diff --git a/assistant/src/ipc/skill-routes/__tests__/memory.test.ts b/assistant/src/ipc/skill-routes/__tests__/memory.test.ts
index 66a07141dd9..b418fef77a7 100644
--- a/assistant/src/ipc/skill-routes/__tests__/memory.test.ts
+++ b/assistant/src/ipc/skill-routes/__tests__/memory.test.ts
@@ -24,6 +24,7 @@ const addMessageSpy = mock(
 );
 mock.module("../../../memory/conversation-crud.js", () => ({
   addMessage: addMessageSpy,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const wakeAgentSpy = mock(
diff --git a/assistant/src/memory/__tests__/jobs-store-enqueue-gate.test.ts b/assistant/src/memory/__tests__/jobs-store-enqueue-gate.test.ts
index 9c97c4aa9dc..258f995c614 100644
--- a/assistant/src/memory/__tests__/jobs-store-enqueue-gate.test.ts
+++ b/assistant/src/memory/__tests__/jobs-store-enqueue-gate.test.ts
@@ -57,6 +57,7 @@ mock.module("../../runtime/actor-trust-resolver.js", () => ({
 // retrospective and auto-analysis paths fall through to the enqueue.
 mock.module("../conversation-crud.js", () => ({
   getConversationSource: () => null,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 mock.module("../auto-analysis-guard.js", () => ({
   isAutoAnalysisConversation: () => false,
diff --git a/assistant/src/memory/__tests__/memory-retrospective-enqueue.test.ts b/assistant/src/memory/__tests__/memory-retrospective-enqueue.test.ts
index 6c9933de357..723aa67f07a 100644
--- a/assistant/src/memory/__tests__/memory-retrospective-enqueue.test.ts
+++ b/assistant/src/memory/__tests__/memory-retrospective-enqueue.test.ts
@@ -19,6 +19,7 @@ const upsertCalls: Array<{
 
 mock.module("../conversation-crud.js", () => ({
   getConversationSource: (_id: string) => sourceTag,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../jobs-store.js", () => ({
diff --git a/assistant/src/memory/__tests__/memory-retrospective-job.test.ts b/assistant/src/memory/__tests__/memory-retrospective-job.test.ts
index 0b7e0b03463..5a0903c5885 100644
--- a/assistant/src/memory/__tests__/memory-retrospective-job.test.ts
+++ b/assistant/src/memory/__tests__/memory-retrospective-job.test.ts
@@ -144,6 +144,7 @@ mock.module("../conversation-crud.js", () => ({
   deleteConversation: (id: string) => {
     deletedConversationIds.push(id);
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../config/assistant-feature-flags.js", () => ({
diff --git a/assistant/src/memory/__tests__/memory-retrospective-startup-cleanup.test.ts b/assistant/src/memory/__tests__/memory-retrospective-startup-cleanup.test.ts
index a19b9e11790..73c289f2c76 100644
--- a/assistant/src/memory/__tests__/memory-retrospective-startup-cleanup.test.ts
+++ b/assistant/src/memory/__tests__/memory-retrospective-startup-cleanup.test.ts
@@ -108,6 +108,7 @@ mock.module("../conversation-crud.js", () => ({
     deletedIds.push(id);
     mockConversations = mockConversations.filter((c) => c.id !== id);
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 import { sweepOrphanMemoryRetrospectiveConversations } from "../memory-retrospective-startup-cleanup.js";
diff --git a/assistant/src/memory/conversation-crud.ts b/assistant/src/memory/conversation-crud.ts
index 3bdec7fd3da..c86ea2a70cb 100644
--- a/assistant/src/memory/conversation-crud.ts
+++ b/assistant/src/memory/conversation-crud.ts
@@ -1977,6 +1977,104 @@ interface WipeConversationResult extends DeletedMemoryIds {
   cancelledJobCount: number;
 }
 
+/**
+ * Reserve an empty message row at a known id, so the agent loop can stamp
+ * outbound streaming events with a stable identity before any content is
+ * produced. The returned row has `content: "[]"` and no metadata-side
+ * effects beyond `addMessage`'s usual conversation-row bump.
+ *
+ * Intentionally skips both Qdrant indexing and attention projection — an
+ * empty placeholder is not meaningful for either. The caller will later
+ * write final content via {@link updateMessageContent} (and is responsible
+ * for triggering any indexing/projection at that point if it cares).
+ *
+ * Mirrors {@link addMessage}'s SQLITE_BUSY/SQLITE_IOERR retry shape so the
+ * primitives behave consistently under WAL contention.
+ */
+export async function reserveMessage(
+  conversationId: string,
+  role: string,
+  metadata?: Record<string, unknown>,
+) {
+  const db = getDb();
+  const messageId = uuid();
+
+  if (metadata) {
+    const result = messageMetadataSchema.safeParse(metadata);
+    if (!result.success) {
+      log.warn(
+        { conversationId, messageId, issues: result.error.issues },
+        "Invalid message metadata, storing as-is",
+      );
+    }
+  }
+
+  const metadataStr = metadata ? JSON.stringify(metadata) : undefined;
+  const originChannelCandidate =
+    metadata && isChannelId(metadata.userMessageChannel)
+      ? metadata.userMessageChannel
+      : null;
+
+  const MAX_RETRIES = 3;
+  let now!: number;
+  for (let attempt = 0; ; attempt++) {
+    now = monotonicNow();
+    try {
+      const values = {
+        id: messageId,
+        conversationId,
+        role,
+        content: "[]",
+        createdAt: now,
+        ...(metadataStr ? { metadata: metadataStr } : {}),
+      };
+      db.transaction((tx) => {
+        tx.insert(messages).values(values).run();
+        if (originChannelCandidate) {
+          tx.update(conversations)
+            .set({ originChannel: originChannelCandidate })
+            .where(
+              and(
+                eq(conversations.id, conversationId),
+                isNull(conversations.originChannel),
+              ),
+            )
+            .run();
+        }
+        tx.update(conversations)
+          .set({ updatedAt: now, lastMessageAt: now })
+          .where(eq(conversations.id, conversationId))
+          .run();
+      });
+      break;
+    } catch (err) {
+      const errCode = (err as { code?: string }).code ?? "";
+      if (
+        attempt < MAX_RETRIES &&
+        (errCode.startsWith("SQLITE_BUSY") ||
+          errCode.startsWith("SQLITE_IOERR"))
+      ) {
+        log.warn(
+          { attempt, conversationId, code: errCode },
+          "reserveMessage: transient SQLite error, retrying",
+        );
+        await Bun.sleep(50 * (attempt + 1));
+        continue;
+      }
+      throw err;
+    }
+  }
+
+  return {
+    id: messageId,
+    conversationId,
+    role,
+    content: "[]",
+    createdAt: now,
+    ...(metadataStr ? { metadata: metadataStr } : {}),
+  };
+}
+
 /**
  * Update the content of an existing message. Used when consolidating
  * multiple assistant messages into one.
diff --git a/assistant/src/notifications/__tests__/emit-signal-home-feed.test.ts b/assistant/src/notifications/__tests__/emit-signal-home-feed.test.ts
index 13c9181892f..51909817f6f 100644
--- a/assistant/src/notifications/__tests__/emit-signal-home-feed.test.ts
+++ b/assistant/src/notifications/__tests__/emit-signal-home-feed.test.ts
@@ -34,6 +34,7 @@ mock.module("../../home/feed-writer.js", () => ({
 // home-feed-side-effect.ts only consumes `getConversation`.
 mock.module("../../memory/conversation-crud.js", () => ({
   getConversation: () => conversationRow,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Stub the broadcaster so emit-signal's `getBroadcaster()` does not need
diff --git a/assistant/src/notifications/__tests__/home-feed-side-effect.test.ts b/assistant/src/notifications/__tests__/home-feed-side-effect.test.ts
index e03afa99206..822915b9002 100644
--- a/assistant/src/notifications/__tests__/home-feed-side-effect.test.ts
+++ b/assistant/src/notifications/__tests__/home-feed-side-effect.test.ts
@@ -30,6 +30,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
     }
     return conversationRow;
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const { writeHomeFeedItemForSignal } =
diff --git a/assistant/src/plugins/defaults/persistence.ts b/assistant/src/plugins/defaults/persistence.ts
index 36326c668b0..a271ca19559 100644
--- a/assistant/src/plugins/defaults/persistence.ts
+++ b/assistant/src/plugins/defaults/persistence.ts
@@ -15,12 +15,17 @@
  *
  * The terminal dispatches on the discriminated {@link PersistArgs.op} field:
  *
- * - `add`    → {@link addMessage}, optionally followed by
- *              {@link syncMessageToDisk} when `args.syncToDisk` is true.
- * - `update` → {@link updateMessageMetadata} (returns `void`, wrapped as
- *              `{ op: "update" }`).
- * - `delete` → {@link deleteMessageById} (returns the segment/summary IDs
- *              the caller must clean up out-of-band).
+ * - `add`           → {@link addMessage}, optionally followed by
+ *                     {@link syncMessageToDisk} when `args.syncToDisk` is true.
+ * - `reserve`       → {@link reserveMessage} — pre-allocates an empty row
+ *                     for assistant anchor stamping.
+ * - `updateContent` → {@link updateMessageContent} — overwrites an existing
+ *                     row's content (returns `void`, wrapped as
+ *                     `{ op: "updateContent" }`).
+ * - `update`        → {@link updateMessageMetadata} (returns `void`, wrapped
+ *                     as `{ op: "update" }`).
+ * - `delete`        → {@link deleteMessageById} (returns the segment/summary
+ *                     IDs the caller must clean up out-of-band).
  *
  * Manifest declares `provides.persistence: "v1"` so other plugins can
  * negotiate against the pipeline surface and `requires.pluginRuntime: "v1"`
@@ -36,6 +41,8 @@
 import {
   addMessage,
   deleteMessageById,
+  reserveMessage,
+  updateMessageContent,
   updateMessageMetadata,
 } from "../../memory/conversation-crud.js";
 import { syncMessageToDisk } from "../../memory/conversation-disk-view.js";
@@ -74,6 +81,18 @@ export async function defaultPersistenceTerminal(
       }
       return { op: "add", message };
     }
+    case "reserve": {
+      const message = await reserveMessage(
+        args.conversationId,
+        args.role,
+        args.metadata,
+      );
+      return { op: "reserve", message };
+    }
+    case "updateContent": {
+      updateMessageContent(args.messageId, args.content);
+      return { op: "updateContent" };
+    }
     case "update": {
       updateMessageMetadata(args.messageId, args.updates);
       return { op: "update" };
diff --git a/assistant/src/plugins/types.ts b/assistant/src/plugins/types.ts
index d51241141a0..1b74d6df7cb 100644
--- a/assistant/src/plugins/types.ts
+++ b/assistant/src/plugins/types.ts
@@ -439,18 +439,25 @@ export interface OverflowReduceResult {
  * Pipeline arguments for `persistence` — a discriminated union over the
  * message-CRUD operations plugins may observe, redirect, or short-circuit:
  *
- * - `add`    — append a new message (`addMessage`). Mirrors
- *              `addMessage(conversationId, role, content, metadata?, opts?)`.
- *              When `syncToDisk` is set, the default plugin also runs
- *              {@link syncMessageToDisk} against the just-persisted row so
- *              the JSONL disk view stays consistent. The `createdAtMs` field
- *              carries the conversation's creation timestamp — needed to
- *              resolve the disk-view directory path.
- * - `update` — shallow-merge metadata into an existing message
- *              (`updateMessageMetadata`). Returns `void`.
- * - `delete` — remove a single message (`deleteMessageById`). Returns the
- *              {@link DeletedMemoryIds}-shaped segment/summary IDs the caller
- *              must clean up out-of-band.
+ * - `add`           — append a new message (`addMessage`). Mirrors
+ *                     `addMessage(conversationId, role, content, metadata?, opts?)`.
+ *                     When `syncToDisk` is set, the default plugin also runs
+ *                     {@link syncMessageToDisk} against the just-persisted row
+ *                     so the JSONL disk view stays consistent. The
+ *                     `createdAtMs` field carries the conversation's creation
+ *                     timestamp — needed to resolve the disk-view directory.
+ * - `reserve`       — pre-allocate an empty assistant anchor row
+ *                     (`reserveMessage`) so the agent loop can stamp streaming
+ *                     events with stable identity before any content is
+ *                     produced. Returns the same row shape as `add`.
+ * - `updateContent` — overwrite the content of an existing message
+ *                     (`updateMessageContent`). Used to finalize a previously
+ *                     reserved row, and by consolidation paths.
+ * - `update`        — shallow-merge metadata into an existing message
+ *                     (`updateMessageMetadata`). Returns `void`.
+ * - `delete`        — remove a single message (`deleteMessageById`). Returns
+ *                     the {@link DeletedMemoryIds}-shaped segment/summary IDs
+ *                     the caller must clean up out-of-band.
  *
  * The discriminated `op` field lets plugin middleware narrow the union and
  * tailor behavior per-operation (e.g. "only observe deletes", "redirect
@@ -473,6 +480,19 @@ export type PersistAddArgs = {
   readonly createdAtMs?: number;
 };
 
+export type PersistReserveArgs = {
+  readonly op: "reserve";
+  readonly conversationId: string;
+  readonly role: string;
+  readonly metadata?: Record<string, unknown>;
+};
+
+export type PersistUpdateContentArgs = {
+  readonly op: "updateContent";
+  readonly messageId: string;
+  readonly content: string;
+};
+
 export type PersistUpdateArgs = {
   readonly op: "update";
   readonly messageId: string;
@@ -486,6 +506,8 @@ export type PersistDeleteArgs = {
 
 export type PersistArgs =
   | PersistAddArgs
+  | PersistReserveArgs
+  | PersistUpdateContentArgs
   | PersistUpdateArgs
   | PersistDeleteArgs;
 
@@ -506,6 +528,25 @@ export type PersistAddResult = {
   };
 };
 
+/**
+ * Result row returned by a `reserve` op — same row shape as `add` but with
+ * empty `content` (`"[]"`) and tagged distinctly so middleware can branch
+ * on intent.
+ */
+export type PersistReserveResult = {
+  readonly op: "reserve";
+  readonly message: {
+    readonly id: string;
+    readonly conversationId: string;
+    readonly role: string;
+    readonly content: string;
+    readonly createdAt: number;
+    readonly metadata?: string;
+  };
+};
+
+export type PersistUpdateContentResult = { readonly op: "updateContent" };
+
 export type PersistUpdateResult = { readonly op: "update" };
 
 /** IDs of segments/summaries the caller must remove from Qdrant. */
@@ -517,6 +558,8 @@ export type PersistDeleteResult = {
 
 export type PersistResult =
   | PersistAddResult
+  | PersistReserveResult
+  | PersistUpdateContentResult
   | PersistUpdateResult
   | PersistDeleteResult;
 
diff --git a/assistant/src/proactive-artifact/job.test.ts b/assistant/src/proactive-artifact/job.test.ts
index 177f49eb992..2b95b89b562 100644
--- a/assistant/src/proactive-artifact/job.test.ts
+++ b/assistant/src/proactive-artifact/job.test.ts
@@ -163,6 +163,7 @@ mock.module("../memory/conversation-crud.js", () => ({
     addMessageCalls.push({ conversationId, role, content, metadata, opts });
     return { id: `msg-${addMessageCalls.length}` };
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // emitNotificationSignal mock
diff --git a/assistant/src/runtime/__tests__/agent-wake.test.ts b/assistant/src/runtime/__tests__/agent-wake.test.ts
index 40e1bb6530a..59beeb27ad5 100644
--- a/assistant/src/runtime/__tests__/agent-wake.test.ts
+++ b/assistant/src/runtime/__tests__/agent-wake.test.ts
@@ -29,6 +29,7 @@ import type { DiskPressureStatus } from "../../daemon/disk-pressure-guard.js";
 mock.module("../../memory/conversation-crud.js", () => ({
   getConversationOverrideProfile: () => undefined,
   getConversation: () => ({ archivedAt: null }),
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 const mockGetOrCreateConversationCalls: Array<{
diff --git a/assistant/src/runtime/__tests__/background-job-runner.test.ts b/assistant/src/runtime/__tests__/background-job-runner.test.ts
index 5c187d6f0e7..8ab01444608 100644
--- a/assistant/src/runtime/__tests__/background-job-runner.test.ts
+++ b/assistant/src/runtime/__tests__/background-job-runner.test.ts
@@ -40,6 +40,7 @@ mock.module("../../memory/conversation-crud.js", () => ({
     addMessageCalls.push({ conversationId, role, content });
     return { id: `msg-${addMessageCalls.length}` };
   },
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 let processMessageImpl: (
diff --git a/assistant/src/runtime/routes/__tests__/conversation-compaction-routes.test.ts b/assistant/src/runtime/routes/__tests__/conversation-compaction-routes.test.ts
index 36641026209..525a2ded8e1 100644
--- a/assistant/src/runtime/routes/__tests__/conversation-compaction-routes.test.ts
+++ b/assistant/src/runtime/routes/__tests__/conversation-compaction-routes.test.ts
@@ -70,6 +70,7 @@ mock.module("../../../memory/conversation-crud.js", () => ({
     state.conversation && state.conversation.id === id
       ? state.conversation
       : null,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../../memory/llm-request-log-source.js", () => ({
diff --git a/assistant/src/runtime/routes/__tests__/home-feed-routes.test.ts b/assistant/src/runtime/routes/__tests__/home-feed-routes.test.ts
index d71d20f47e0..5bb4757e382 100644
--- a/assistant/src/runtime/routes/__tests__/home-feed-routes.test.ts
+++ b/assistant/src/runtime/routes/__tests__/home-feed-routes.test.ts
@@ -62,6 +62,7 @@ mock.module("../../../memory/conversation-crud.js", () => ({
   getMessages: () => [],
   getMessagesPaginated: () => ({ messages: [], hasMore: false }),
   getMessageById: () => null,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 // Dynamic imports so module mocks are wired before evaluation.
diff --git a/assistant/src/runtime/services/__tests__/analyze-conversation.test.ts b/assistant/src/runtime/services/__tests__/analyze-conversation.test.ts
index 64be2592a45..3a57906542d 100644
--- a/assistant/src/runtime/services/__tests__/analyze-conversation.test.ts
+++ b/assistant/src/runtime/services/__tests__/analyze-conversation.test.ts
@@ -46,6 +46,7 @@ mock.module("../../../memory/conversation-crud.js", () => ({
   addMessage: mockAddMessage,
   findAnalysisConversationFor: mockFindAnalysisConversationFor,
   getConversationSource: mockGetConversationSource,
+  reserveMessage: mock(async () => ({ id: "msg-reserve" })),
 }));
 
 mock.module("../../../export/transcript-formatter.js", () => ({