diff --git a/docs/providers.md b/docs/providers.md
index 7595240bd..537acd5ed 100644
--- a/docs/providers.md
+++ b/docs/providers.md
@@ -44,6 +44,8 @@ OpenCode owns user message IDs. Do not pass Paseo-generated IDs to OpenCode prom
 
 Every provider adapter owns its canonical user-message timeline rows. When a foreground prompt is accepted, the adapter must emit exactly one `user_message` timeline item for that submitted prompt, using the same message ID it gives to or receives from the provider runtime. Optimistic client messages are UI-only and provider transcript echoes are optional; neither is allowed to be the only source of truth. If the provider later echoes the same submitted user message, dedupe it only within the active turn. Prefer provider-visible message IDs, but ACP runtimes may omit that ID or replace it with a provider-owned one; in that case suppress only echo chunks whose accumulated text is a prefix of the active submitted prompt. Do not perform global transcript text dedupe.
 
+Submitted user-message rows preserve both identities: `messageId` is the provider-visible ID and the optional `clientMessageId` is the Paseo ID from `AgentRunOptions`. Attach `clientMessageId` only to the canonical row for that foreground submission; provider history and externally initiated user rows do not have a Paseo client ID.
+
 Draft metadata lookups should avoid creating provider sessions when the upstream provider has top-level APIs for that metadata. Prefer `AgentClient.fetchCatalog`, `listCommands`, or `listFeatures` over creating a scratch `AgentSession`; scratch sessions can show up as empty native sessions in provider import/history UIs. `fetchCatalog` is the single discovery API for models and modes — provider implementations may use one process, separate upstream calls, or static data internally, but callers outside the provider do not get separate runtime model/mode probes. Draft feature and command listing must use the explicit draft model only; if no model is selected yet, return no metadata instead of resolving a default model through catalog discovery.
 
 Provider session import has its own contract. The picker calls `listImportableSessions` and receives rows only: provider handle, cwd, title, prompt previews, and last activity. Import calls `importSession({ providerHandleId, cwd })` for the selected row and must not call listing again. The provider returns the resumed session, storage config, persistence handle, and hydrated timeline for that one native session; `AgentManager.importProviderSession` seeds the daemon timeline and publishes the Paseo agent only after it is ready.
diff --git a/docs/timeline-sync.md b/docs/timeline-sync.md
index e90abf412..e96250f0d 100644
--- a/docs/timeline-sync.md
+++ b/docs/timeline-sync.md
@@ -83,6 +83,10 @@ the existing optimistic-message rules, then restores any unmatched prompts after
 history. This keeps late history before a newly submitted prompt without duplicating an
 acknowledged prompt.
 
+Canonical submitted user rows carry the provider's `messageId` and Paseo's optional
+`clientMessageId`. Clients reconcile optimistic prompts by `clientMessageId`. Content matching is
+limited to the dated compatibility path for daemon timelines created before that field existed.
+
 ## Relevant code
 
 - Server live stream forwarding: `packages/server/src/server/session.ts`
diff --git a/packages/app/src/timeline/session-stream-reducers.test.ts b/packages/app/src/timeline/session-stream-reducers.test.ts
index 05048e2d5..1b84d2e15 100644
--- a/packages/app/src/timeline/session-stream-reducers.test.ts
+++ b/packages/app/src/timeline/session-stream-reducers.test.ts
@@ -538,7 +538,7 @@ describe("processTimelineResponse", () => {
     expect(result.error).toBe(null);
   });
 
-  it("reconciles an optimistic user message during an after-page response", () => {
+  it("reconciles a legacy canonical user message by content during an after-page response", () => {
     const existingCursor: TimelineCursor = {
       epoch: "epoch-1",
       startSeq: 1,
@@ -559,7 +559,7 @@ describe("processTimelineResponse", () => {
             item: {
               type: "user_message",
               text: "sent while catching up",
-              messageId: "optimistic-after",
+              messageId: "canonical-after",
             },
           },
         ],
@@ -568,7 +568,42 @@ describe("processTimelineResponse", () => {
 
     const userMessages = result.tail.filter((item) => item.kind === "user_message");
     expect(userMessages).toHaveLength(1);
-    expect(userMessages[0]?.id).toBe("optimistic-after");
+    expect(userMessages[0]?.id).toBe("canonical-after");
+    expect(userMessages[0]?.optimistic).toBeUndefined();
+  });
+
+  it("reconciles an optimistic user message by client message id", () => {
+    const optimistic = makeOptimisticUserMessage("local presentation", "client-message");
+
+    const result = processTimelineResponse({
+      ...baseTimelineInput,
+      currentTail: [optimistic],
+      currentCursor: { epoch: "epoch-1", startSeq: 1, endSeq: 1 },
+      payload: {
+        ...baseTimelineInput.payload,
+        epoch: "epoch-1",
+        entries: [
+          {
+            ...makeTimelineEntry(2, "provider presentation", "user_message"),
+            item: {
+              type: "user_message",
+              text: "provider presentation",
+              messageId: "provider-message",
+              clientMessageId: "client-message",
+            },
+          },
+        ],
+      },
+    });
+
+    const userMessages = result.tail.filter((item) => item.kind === "user_message");
+    expect(userMessages).toEqual([
+      expect.objectContaining({
+        id: "provider-message",
+        clientMessageId: "client-message",
+        text: "local presentation",
+      }),
+    ]);
     expect(userMessages[0]?.optimistic).toBeUndefined();
   });
 
@@ -1178,7 +1213,7 @@ describe("processTimelineResponse", () => {
     ]);
   });
 
-  it("does not match equal prompt text when canonical message ids differ", () => {
+  it("does not match equal prompt text when canonical client message ids differ", () => {
     const prompt = makeOptimisticUserMessage("continue", "local-prompt");
 
     const result = processTimelineResponse({
@@ -1197,6 +1232,7 @@ describe("processTimelineResponse", () => {
               type: "user_message",
               text: "continue",
               messageId: "remote-prompt",
+              clientMessageId: "remote-client-prompt",
             },
           },
         ],
diff --git a/packages/app/src/timeline/session-stream-reducers.ts b/packages/app/src/timeline/session-stream-reducers.ts
index 854832762..1ae2708f6 100644
--- a/packages/app/src/timeline/session-stream-reducers.ts
+++ b/packages/app/src/timeline/session-stream-reducers.ts
@@ -312,6 +312,7 @@ function mergeCanonicalUserWithLocalPresentation(
   return {
     kind: "user_message",
     id: canonical.id,
+    ...(canonical.clientMessageId ? { clientMessageId: canonical.clientMessageId } : {}),
     text: local.text,
     timestamp: local.timestamp,
     ...(local.images && local.images.length > 0 ? { images: local.images } : {}),
@@ -321,6 +322,27 @@ function mergeCanonicalUserWithLocalPresentation(
   };
 }
 
+interface CanonicalUserMessageIdentity {
+  messageId?: string;
+  clientMessageId?: string;
+  text: string;
+}
+
+function matchesOptimisticUserMessageIdentity(
+  canonical: CanonicalUserMessageIdentity,
+  optimistic: UserMessageItem,
+): boolean {
+  if (canonical.clientMessageId !== undefined) {
+    return canonical.clientMessageId === optimistic.id;
+  }
+  if (canonical.messageId === optimistic.id) {
+    return true;
+  }
+  // COMPAT(userMessageClientId): added in v0.2.0, remove after 2027-01-20 once
+  // the supported daemon floor emits clientMessageId on submitted user messages.
+  return canonical.text.length > 0 && canonical.text === optimistic.text;
+}
+
 function reconcileLocalUserPresentationAfterReplace(params: {
   canonicalTail: StreamItem[];
   previousTail: StreamItem[];
@@ -352,6 +374,21 @@ function reconcileLocalUserPresentationAfterReplace(params: {
         return false;
       }
       if (local.item.optimistic) {
+        const canonical = params.canonicalTail[index];
+        if (canonical?.kind !== "user_message") {
+          return false;
+        }
+        const identityMatches = matchesOptimisticUserMessageIdentity(
+          {
+            messageId: canonical.id,
+            clientMessageId: canonical.clientMessageId,
+            text: canonical.text,
+          },
+          local.item,
+        );
+        if (canonical.clientMessageId !== undefined || identityMatches) {
+          return identityMatches;
+        }
         return ordinal >= local.ordinal;
       }
       return params.canonicalTail[index]?.id === local.item.id;
@@ -773,10 +810,7 @@ function matchesOptimisticUserMessage(params: {
   if (event.type !== "timeline" || event.item.type !== "user_message") {
     return false;
   }
-  if (event.item.messageId !== undefined) {
-    return event.item.messageId === params.optimistic.id;
-  }
-  return event.item.text.length > 0 && event.item.text === params.optimistic.text;
+  return matchesOptimisticUserMessageIdentity(event.item, params.optimistic);
 }
 
 function acknowledgeOptimisticUserMessage(params: {
diff --git a/packages/app/src/types/stream.ts b/packages/app/src/types/stream.ts
index 13728a70e..21d2726d3 100644
--- a/packages/app/src/types/stream.ts
+++ b/packages/app/src/types/stream.ts
@@ -86,6 +86,7 @@ export type UserMessageImageAttachment = AttachmentMetadata;
 export interface UserMessageItem {
   kind: "user_message";
   id: string;
+  clientMessageId?: string;
   text: string;
   timestamp: Date;
   optimistic?: true;
@@ -238,6 +239,7 @@ function markThoughtReady(item: ThoughtItem): ThoughtItem {
 
 function buildUserMessageItem(input: {
   id: string;
+  clientMessageId?: string;
   text: string;
   timestamp: Date;
   optimistic?: UserMessageItem | null;
@@ -246,6 +248,7 @@ function buildUserMessageItem(input: {
     return {
       kind: "user_message",
       id: input.id,
+      ...(input.clientMessageId ? { clientMessageId: input.clientMessageId } : {}),
       text: input.optimistic.text,
       timestamp: input.optimistic.timestamp,
       ...(input.optimistic.images && input.optimistic.images.length > 0
@@ -260,6 +263,7 @@ function buildUserMessageItem(input: {
   return {
     kind: "user_message",
     id: input.id,
+    ...(input.clientMessageId ? { clientMessageId: input.clientMessageId } : {}),
     text: input.text,
     timestamp: input.timestamp,
   };
@@ -351,6 +355,7 @@ function appendUserMessage(
   text: string,
   timestamp: Date,
   messageId?: string,
+  clientMessageId?: string,
 ): StreamItem[] {
   const { chunk, hasContent } = normalizeChunk(text);
   if (!hasContent) {
@@ -366,6 +371,7 @@ function appendUserMessage(
 
   const nextItem = buildUserMessageItem({
     id: entryId,
+    clientMessageId,
     text: chunk,
     timestamp,
     optimistic,
@@ -833,7 +839,9 @@ function reduceTimelineEvent(
   const item = event.item;
   switch (item.type) {
     case "user_message":
-      return finalizeActiveThoughts(appendUserMessage(state, item.text, timestamp, item.messageId));
+      return finalizeActiveThoughts(
+        appendUserMessage(state, item.text, timestamp, item.messageId, item.clientMessageId),
+      );
     case "assistant_message":
       return finalizeActiveThoughts(
         appendAssistantMessage(
diff --git a/packages/protocol/src/agent-types.ts b/packages/protocol/src/agent-types.ts
index 54b5275cf..756ea3fd1 100644
--- a/packages/protocol/src/agent-types.ts
+++ b/packages/protocol/src/agent-types.ts
@@ -338,7 +338,7 @@ export interface CompactionTimelineItem {
 }
 
 export type AgentTimelineItem =
-  | { type: "user_message"; text: string; messageId?: string }
+  | { type: "user_message"; text: string; messageId?: string; clientMessageId?: string }
   | { type: "assistant_message"; text: string; messageId?: string }
   | { type: "reasoning"; text: string }
   | ToolCallTimelineItem
diff --git a/packages/protocol/src/messages.ts b/packages/protocol/src/messages.ts
index a566f8e5c..f4b419864 100644
--- a/packages/protocol/src/messages.ts
+++ b/packages/protocol/src/messages.ts
@@ -570,6 +570,7 @@ export const AgentTimelineItemPayloadSchema: z.ZodType<AgentTimelineItem, unknow
     type: z.literal("user_message"),
     text: z.string(),
     messageId: z.string().optional(),
+    clientMessageId: z.string().optional(),
   }),
   z.object({
     type: z.literal("assistant_message"),
diff --git a/packages/server/src/server/agent/agent-manager.test.ts b/packages/server/src/server/agent/agent-manager.test.ts
index e5f20da37..6edd2db6d 100644
--- a/packages/server/src/server/agent/agent-manager.test.ts
+++ b/packages/server/src/server/agent/agent-manager.test.ts
@@ -7881,7 +7881,12 @@ test("authoritative timeline includes provider-emitted submitted user prompt", a
           type: "timeline",
           provider: this.provider,
           turnId,
-          item: { type: "user_message", text, messageId: options?.messageId },
+          item: {
+            type: "user_message",
+            text,
+            messageId: "provider-message-1",
+            clientMessageId: options?.clientMessageId,
+          },
         });
         this.pushEvent({ type: "turn_completed", provider: this.provider, turnId });
       }, 0);
@@ -7907,13 +7912,16 @@ test("authoritative timeline includes provider-emitted submitted user prompt", a
       workspaceId: undefined,
     });
 
-    await manager.runAgent(snapshot.id, "hello from composer", { messageId: "msg-client-1" });
+    await manager.runAgent(snapshot.id, "hello from composer", {
+      clientMessageId: "msg-client-1",
+    });
 
     const timeline = manager.fetchTimeline(snapshot.id, { direction: "tail", limit: 20 }).rows;
     expect(timeline.map((row) => row.item)).toContainEqual({
       type: "user_message",
       text: "hello from composer",
-      messageId: "msg-client-1",
+      messageId: "provider-message-1",
+      clientMessageId: "msg-client-1",
     });
   } finally {
     await manager.flush().catch(() => undefined);
diff --git a/packages/server/src/server/agent/agent-prompt.test.ts b/packages/server/src/server/agent/agent-prompt.test.ts
index f42061698..ba3c64f5e 100644
--- a/packages/server/src/server/agent/agent-prompt.test.ts
+++ b/packages/server/src/server/agent/agent-prompt.test.ts
@@ -190,7 +190,7 @@ test("sendPromptToAgent forwards the client message id as run options", async ()
 
   expect(streamAgentSpy).toHaveBeenCalledWith("agent-1", "hello", {
     outputSchema: { type: "object" },
-    messageId: "msg-client-1",
+    clientMessageId: "msg-client-1",
   });
 });
 
diff --git a/packages/server/src/server/agent/agent-prompt.ts b/packages/server/src/server/agent/agent-prompt.ts
index 96b4c9c29..22bd8cdc2 100644
--- a/packages/server/src/server/agent/agent-prompt.ts
+++ b/packages/server/src/server/agent/agent-prompt.ts
@@ -198,7 +198,7 @@ export async function sendPromptToAgent(
   }
 
   const runOptions = params.messageId
-    ? { ...params.runOptions, messageId: params.messageId }
+    ? { ...params.runOptions, clientMessageId: params.messageId }
     : params.runOptions;
 
   return await startAgentRun(params.agentManager, params.agentId, params.prompt, params.logger, {
diff --git a/packages/server/src/server/agent/agent-sdk-types.ts b/packages/server/src/server/agent/agent-sdk-types.ts
index c5b8e37b1..6836cd8bc 100644
--- a/packages/server/src/server/agent/agent-sdk-types.ts
+++ b/packages/server/src/server/agent/agent-sdk-types.ts
@@ -199,7 +199,7 @@ export interface AgentRunOptions {
   outputSchema?: unknown;
   resumeFrom?: AgentPersistenceHandle;
   maxThinkingTokens?: number;
-  messageId?: string;
+  clientMessageId?: string;
 }
 
 export interface AgentUsage {
@@ -368,7 +368,7 @@ export interface CompactionTimelineItem {
 }
 
 export type AgentTimelineItem =
-  | { type: "user_message"; text: string; messageId?: string }
+  | { type: "user_message"; text: string; messageId?: string; clientMessageId?: string }
   | { type: "assistant_message"; text: string; messageId?: string }
   | { type: "reasoning"; text: string }
   | ToolCallTimelineItem
diff --git a/packages/server/src/server/agent/create-agent/create.test.ts b/packages/server/src/server/agent/create-agent/create.test.ts
index e5c90efc2..89cf7bab6 100644
--- a/packages/server/src/server/agent/create-agent/create.test.ts
+++ b/packages/server/src/server/agent/create-agent/create.test.ts
@@ -75,7 +75,7 @@ test("session create forwards clientMessageId to the initial prompt run options"
   });
 
   expect(streamAgent).toHaveBeenCalledWith("agent-1", "hello from create", {
-    messageId: "msg-create-1",
+    clientMessageId: "msg-create-1",
   });
 });
 
diff --git a/packages/server/src/server/agent/create-agent/create.ts b/packages/server/src/server/agent/create-agent/create.ts
index 182edc833..b31a858f3 100644
--- a/packages/server/src/server/agent/create-agent/create.ts
+++ b/packages/server/src/server/agent/create-agent/create.ts
@@ -271,7 +271,7 @@ async function resolveSessionCreateAgent(
     input.outputSchema || clientMessageId
       ? {
           ...(input.outputSchema ? { outputSchema: input.outputSchema } : {}),
-          ...(clientMessageId ? { messageId: clientMessageId } : {}),
+          ...(clientMessageId ? { clientMessageId } : {}),
         }
       : undefined;
   const workspaceId = setupContinuation ? createdWorkspaceId : input.workspaceId;
diff --git a/packages/server/src/server/agent/providers/acp-agent.test.ts b/packages/server/src/server/agent/providers/acp-agent.test.ts
index d95ebbd65..201d4e0e4 100644
--- a/packages/server/src/server/agent/providers/acp-agent.test.ts
+++ b/packages/server/src/server/agent/providers/acp-agent.test.ts
@@ -2329,7 +2329,9 @@ describe("ACPAgentSession", () => {
       events.push(event);
     });
 
-    const { turnId } = await session.startTurn("hello", { messageId: "msg-client-1" });
+    const { turnId } = await session.startTurn("hello", {
+      clientMessageId: "msg-client-1",
+    });
 
     expect(prompt).toHaveBeenCalledWith({
       sessionId: "session-1",
@@ -2343,7 +2345,12 @@ describe("ACPAgentSession", () => {
         type: "timeline",
         provider: "claude-acp",
         turnId,
-        item: { type: "user_message", text: "hello", messageId: "msg-client-1" },
+        item: {
+          type: "user_message",
+          text: "hello",
+          messageId: "msg-client-1",
+          clientMessageId: "msg-client-1",
+        },
       },
     ]);
 
@@ -2362,7 +2369,7 @@ describe("ACPAgentSession", () => {
       events.push(event);
     });
 
-    await session.startTurn("hello", { messageId: "msg-client-1" });
+    await session.startTurn("hello", { clientMessageId: "msg-client-1" });
     await session.sessionUpdate({
       sessionId: "session-1",
       update: {
@@ -2389,7 +2396,7 @@ describe("ACPAgentSession", () => {
       events.push(event);
     });
 
-    await session.startTurn("hello", { messageId: "msg-client-1" });
+    await session.startTurn("hello", { clientMessageId: "msg-client-1" });
     await session.sessionUpdate({
       sessionId: "session-1",
       update: {
@@ -2404,7 +2411,12 @@ describe("ACPAgentSession", () => {
       {
         type: "timeline",
         provider: "claude-acp",
-        item: { type: "user_message", text: "hello", messageId: "msg-client-1" },
+        item: {
+          type: "user_message",
+          text: "hello",
+          messageId: "msg-client-1",
+          clientMessageId: "msg-client-1",
+        },
         turnId: expect.any(String),
       },
     ]);
@@ -2428,7 +2440,7 @@ describe("ACPAgentSession", () => {
       events.push(event);
     });
 
-    await session.startTurn("first", { messageId: "msg-client-1" });
+    await session.startTurn("first", { clientMessageId: "msg-client-1" });
     await session.sessionUpdate({
       sessionId: "session-1",
       update: {
@@ -2440,7 +2452,7 @@ describe("ACPAgentSession", () => {
     await Promise.resolve();
     await Promise.resolve();
 
-    await session.startTurn("second", { messageId: "msg-client-2" });
+    await session.startTurn("second", { clientMessageId: "msg-client-2" });
     await session.sessionUpdate({
       sessionId: "session-1",
       update: {
@@ -2455,13 +2467,23 @@ describe("ACPAgentSession", () => {
       {
         type: "timeline",
         provider: "claude-acp",
-        item: { type: "user_message", text: "first", messageId: "msg-client-1" },
+        item: {
+          type: "user_message",
+          text: "first",
+          messageId: "msg-client-1",
+          clientMessageId: "msg-client-1",
+        },
         turnId: expect.any(String),
       },
       {
         type: "timeline",
         provider: "claude-acp",
-        item: { type: "user_message", text: "second", messageId: "msg-client-2" },
+        item: {
+          type: "user_message",
+          text: "second",
+          messageId: "msg-client-2",
+          clientMessageId: "msg-client-2",
+        },
         turnId: expect.any(String),
       },
     ]);
@@ -2479,7 +2501,7 @@ describe("ACPAgentSession", () => {
       events.push(event);
     });
 
-    await session.startTurn("hello", { messageId: "msg-client-1" });
+    await session.startTurn("hello", { clientMessageId: "msg-client-1" });
     await session.sessionUpdate({
       sessionId: "session-1",
       update: {
@@ -2495,7 +2517,12 @@ describe("ACPAgentSession", () => {
       {
         type: "timeline",
         provider: "claude-acp",
-        item: { type: "user_message", text: "hello", messageId: "msg-client-1" },
+        item: {
+          type: "user_message",
+          text: "hello",
+          messageId: "msg-client-1",
+          clientMessageId: "msg-client-1",
+        },
         turnId: expect.any(String),
       },
     ]);
diff --git a/packages/server/src/server/agent/providers/acp-agent.ts b/packages/server/src/server/agent/providers/acp-agent.ts
index 6da37dad6..ddb28b01d 100644
--- a/packages/server/src/server/agent/providers/acp-agent.ts
+++ b/packages/server/src/server/agent/providers/acp-agent.ts
@@ -1474,13 +1474,13 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     }
 
     const turnId = randomUUID();
-    const messageId = options?.messageId ?? randomUUID();
+    const messageId = options?.clientMessageId ?? randomUUID();
     this.activeForegroundTurnId = turnId;
     this.fallbackAssistantMessageId = null;
     this.activeSubmittedUserMessage = null;
     this.emitBootstrapThreadEvent();
     this.pushEvent({ type: "turn_started", provider: this.provider, turnId });
-    this.emitSubmittedUserMessage(prompt, messageId, turnId);
+    this.emitSubmittedUserMessage(prompt, messageId, turnId, options?.clientMessageId);
 
     void this.connection
       .prompt({
@@ -2687,6 +2687,7 @@ export class ACPAgentSession implements AgentSession, ACPClient {
     prompt: AgentPromptInput,
     messageId: string,
     turnId: string,
+    clientMessageId?: string,
   ): void {
     const text = extractPromptText(prompt);
     if (text.trim().length === 0) {
@@ -2698,7 +2699,12 @@ export class ACPAgentSession implements AgentSession, ACPClient {
       type: "timeline",
       provider: this.provider,
       turnId,
-      item: { type: "user_message", text, messageId },
+      item: {
+        type: "user_message",
+        text,
+        messageId,
+        ...(clientMessageId ? { clientMessageId } : {}),
+      },
     });
   }
 
diff --git a/packages/server/src/server/agent/providers/claude/agent.ts b/packages/server/src/server/agent/providers/claude/agent.ts
index 4a07fd4fe..6497a9e96 100644
--- a/packages/server/src/server/agent/providers/claude/agent.ts
+++ b/packages/server/src/server/agent/providers/claude/agent.ts
@@ -2043,7 +2043,7 @@ class ClaudeAgentSession implements AgentSession {
 
   async startTurn(
     prompt: AgentPromptInput,
-    _options?: AgentRunOptions,
+    options?: AgentRunOptions,
   ): Promise<{ turnId: string }> {
     if (this.closed) {
       throw new Error("Claude session is closed");
@@ -2109,7 +2109,7 @@ class ClaudeAgentSession implements AgentSession {
       this.input.push(sdkMessage);
       setTimeout(() => {
         if (this.activeForegroundTurnId === turnId) {
-          this.emitSubmittedUserMessage(sdkMessage, turnId);
+          this.emitSubmittedUserMessage(sdkMessage, turnId, options?.clientMessageId);
         }
       }, 0);
     } catch (error) {
@@ -3686,6 +3686,7 @@ class ClaudeAgentSession implements AgentSession {
   private emitSubmittedUserMessage(
     message: Extract<SDKMessage, { type: "user" }>,
     turnId: string,
+    clientMessageId?: string,
   ): void {
     const events: AgentStreamEvent[] = [];
     this.appendUserMessageEvents(message, events);
@@ -3695,7 +3696,11 @@ class ClaudeAgentSession implements AgentSession {
     this.foregroundHasVisibleActivity = true;
     for (const event of events) {
       if (event.type === "timeline") {
-        this.notifySubscribers({ ...event, turnId });
+        const item =
+          event.item.type === "user_message" && clientMessageId
+            ? { ...event.item, clientMessageId }
+            : event.item;
+        this.notifySubscribers({ ...event, item, turnId });
       } else {
         this.notifySubscribers(event);
       }
diff --git a/packages/server/src/server/agent/providers/codex-app-server-agent.test.ts b/packages/server/src/server/agent/providers/codex-app-server-agent.test.ts
index 4c05495fa..a9df432f4 100644
--- a/packages/server/src/server/agent/providers/codex-app-server-agent.test.ts
+++ b/packages/server/src/server/agent/providers/codex-app-server-agent.test.ts
@@ -1014,6 +1014,30 @@ describe("Codex app-server provider", () => {
     await session.close();
   });
 
+  test("correlates a Codex user message with the submitting client message", async () => {
+    const appServer = createFakeCodexAppServer();
+    const session = new CodexAppServerAgentSession(
+      createConfig({ cwd: "/workspace/project" }),
+      null,
+      createTestLogger(),
+      async () => appServer.child,
+    );
+
+    await session.startTurn("remember this", { clientMessageId: "client-message" });
+    const userMessage = waitForNextTimelineItem(session, "user_message");
+    emitCodexUserMessage(appServer, { id: "codex-message", text: "remember this" });
+
+    await expect(userMessage).resolves.toMatchObject({
+      item: {
+        type: "user_message",
+        messageId: "codex-message",
+        clientMessageId: "client-message",
+      },
+    });
+    appServer.completeTurn();
+    await session.close();
+  });
+
   test("configures Codex app-server to use a custom provider base URL", async () => {
     const capturedRequests = await runCustomCodexProviderTurn(
       "codex-iisb",
diff --git a/packages/server/src/server/agent/providers/codex-app-server-agent.ts b/packages/server/src/server/agent/providers/codex-app-server-agent.ts
index 165e1a30d..ac3017dac 100644
--- a/packages/server/src/server/agent/providers/codex-app-server-agent.ts
+++ b/packages/server/src/server/agent/providers/codex-app-server-agent.ts
@@ -3096,6 +3096,7 @@ export class CodexAppServerAgentSession implements AgentSession {
   private readonly subscribers = new Set<(event: AgentStreamEvent) => void>();
   private nextTurnOrdinal = 0;
   private activeForegroundTurnId: string | null = null;
+  private activeClientMessageId: string | null = null;
   private cachedRuntimeInfo: AgentRuntimeInfo | null = null;
   private serviceTier: "fast" | null = null;
   private planModeEnabled = false;
@@ -3820,6 +3821,7 @@ export class CodexAppServerAgentSession implements AgentSession {
 
     const turnId = this.createTurnId();
     this.activeForegroundTurnId = turnId;
+    this.activeClientMessageId = options?.clientMessageId ?? null;
     this.currentTurnId = null;
 
     try {
@@ -3835,6 +3837,7 @@ export class CodexAppServerAgentSession implements AgentSession {
       await this.client.request("turn/start", turnStart.params, TURN_START_TIMEOUT_MS);
     } catch (error) {
       this.activeForegroundTurnId = null;
+      this.activeClientMessageId = null;
       throw error;
     }
 
@@ -4238,6 +4241,7 @@ export class CodexAppServerAgentSession implements AgentSession {
     this.pendingSubAgentNotificationsByThreadId.clear();
     this.subscribers.clear();
     this.activeForegroundTurnId = null;
+    this.activeClientMessageId = null;
     if (this.client) {
       await this.client.dispose();
     }
@@ -5287,6 +5291,7 @@ export class CodexAppServerAgentSession implements AgentSession {
       });
     }
     this.activeForegroundTurnId = null;
+    this.activeClientMessageId = null;
     this.pendingSubAgentNotificationsByThreadId.clear();
     this.resetTurnTrackingState();
   }
@@ -5825,7 +5830,11 @@ export class CodexAppServerAgentSession implements AgentSession {
     if (!this.rememberCodexUserMessageTurn(timelineItem.messageId)) {
       return;
     }
-    this.emitEvent({ type: "timeline", provider: CODEX_PROVIDER, item: timelineItem });
+    const item = this.activeClientMessageId
+      ? { ...timelineItem, clientMessageId: this.activeClientMessageId }
+      : timelineItem;
+    this.activeClientMessageId = null;
+    this.emitEvent({ type: "timeline", provider: CODEX_PROVIDER, item });
   }
 
   private warnUnknownNotificationMethod(method: string, params: unknown): void {
diff --git a/packages/server/src/server/agent/providers/mock-load-test-agent.ts b/packages/server/src/server/agent/providers/mock-load-test-agent.ts
index d371ef1ac..33b9ddfac 100644
--- a/packages/server/src/server/agent/providers/mock-load-test-agent.ts
+++ b/packages/server/src/server/agent/providers/mock-load-test-agent.ts
@@ -606,7 +606,7 @@ export class MockLoadTestAgentSession implements AgentSession {
 
   async startTurn(
     prompt: AgentPromptInput,
-    _options?: AgentRunOptions,
+    options?: AgentRunOptions,
   ): Promise<{ turnId: string }> {
     if (this.activeTurn) {
       throw new Error("Mock load-test provider already has an active turn");
@@ -648,6 +648,7 @@ export class MockLoadTestAgentSession implements AgentSession {
           type: "user_message",
           text: promptToText(prompt),
           messageId: userMessageId,
+          ...(options?.clientMessageId ? { clientMessageId: options.clientMessageId } : {}),
         },
       });
     }, 0);
diff --git a/packages/server/src/server/agent/providers/omp/agent.ts b/packages/server/src/server/agent/providers/omp/agent.ts
index 1e002c9f4..28ca8784d 100644
--- a/packages/server/src/server/agent/providers/omp/agent.ts
+++ b/packages/server/src/server/agent/providers/omp/agent.ts
@@ -896,6 +896,7 @@ export class OmpAgentSession implements AgentSession {
   private activeAskUserDialog: ActiveAskUserDialog | null = null;
   private pendingCombinedAskUserResponse: PendingCombinedAskUserResponse | null = null;
   private activeTurnId: string | null = null;
+  private activeClientMessageId: string | null = null;
   private activeAssistantMessageId: string | null = null;
   private activeTurnStarted = false;
   private activeTurnHasUserMessage = false;
@@ -974,7 +975,7 @@ export class OmpAgentSession implements AgentSession {
     });
   }
 
-  async startTurn(prompt: AgentPromptInput, _options?: AgentRunOptions): Promise<StartTurnResult> {
+  async startTurn(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<StartTurnResult> {
     if (this.activeTurnId) {
       throw new Error("An OMP turn is already active");
     }
@@ -983,6 +984,7 @@ export class OmpAgentSession implements AgentSession {
     const turnId = randomUUID();
     this.live = true;
     this.activeTurnId = turnId;
+    this.activeClientMessageId = options?.clientMessageId ?? null;
     this.activeAssistantMessageId = null;
     this.activeTurnStarted = false;
     this.activeTurnHasUserMessage = false;
@@ -1010,6 +1012,7 @@ export class OmpAgentSession implements AgentSession {
           return;
         }
         this.activeTurnId = null;
+        this.activeClientMessageId = null;
         this.activeTurnStarted = false;
         this.activeTurnHasUserMessage = false;
         this.activeAssistantMessageId = null;
@@ -1143,6 +1146,7 @@ export class OmpAgentSession implements AgentSession {
     }
     if (turnId && this.activeTurnId === turnId) {
       this.activeTurnId = null;
+      this.activeClientMessageId = null;
       this.activeTurnStarted = false;
       this.activeTurnHasUserMessage = false;
       this.activeAssistantMessageId = null;
@@ -1329,6 +1333,7 @@ export class OmpAgentSession implements AgentSession {
         item: {
           type: "user_message",
           text: promptText,
+          ...(this.activeClientMessageId ? { clientMessageId: this.activeClientMessageId } : {}),
         },
       });
     }
@@ -1764,6 +1769,7 @@ export class OmpAgentSession implements AgentSession {
     }
     const turnId = this.activeTurnId;
     this.activeTurnId = null;
+    this.activeClientMessageId = null;
     this.activeTurnStarted = false;
     this.activeTurnHasUserMessage = false;
     this.clearNoTurnBuffers();
@@ -2003,6 +2009,7 @@ export class OmpAgentSession implements AgentSession {
     }
     const nativeMessage = event.message as OmpAgentMessage & { id?: unknown; entryId?: unknown };
     const messageId = readNativeMessageId(nativeMessage);
+    const clientMessageId = this.activeClientMessageId;
     const emitUserMessage = (resolvedMessageId?: string): void => {
       if (resolvedMessageId) {
         // OMP re-emits user message_end frames for entries it has already
@@ -2021,6 +2028,7 @@ export class OmpAgentSession implements AgentSession {
           type: "user_message",
           text,
           ...(resolvedMessageId ? { messageId: resolvedMessageId } : {}),
+          ...(clientMessageId ? { clientMessageId } : {}),
         },
       });
     };
@@ -2085,6 +2093,7 @@ export class OmpAgentSession implements AgentSession {
 
   private completeTurn(turnId: string | undefined, messages: OmpAgentMessage[]): void {
     this.activeTurnId = null;
+    this.activeClientMessageId = null;
     this.activeAssistantMessageId = null;
     this.activeTurnStarted = false;
     this.activeTurnHasUserMessage = false;
diff --git a/packages/server/src/server/agent/providers/opencode-agent.ts b/packages/server/src/server/agent/providers/opencode-agent.ts
index aabd1b627..0eeca0e7f 100644
--- a/packages/server/src/server/agent/providers/opencode-agent.ts
+++ b/packages/server/src/server/agent/providers/opencode-agent.ts
@@ -1707,6 +1707,7 @@ export interface OpenCodeEventTranslationState {
   cwd?: string;
   messageRoles: Map<string, OpenCodeMessageRole>;
   pendingUserMessageText?: string | null;
+  pendingClientMessageId?: string | null;
   emittedUserMessageIds?: Set<string>;
   accumulatedUsage: AgentUsage;
   sessionTotalCostUsd?: number;
@@ -2370,7 +2371,12 @@ function appendOpenCodeUserMessageUpdated(
   events.push({
     type: "timeline",
     provider: "opencode",
-    item: { type: "user_message", text, messageId: info.id },
+    item: {
+      type: "user_message",
+      text,
+      messageId: info.id,
+      ...(state.pendingClientMessageId ? { clientMessageId: state.pendingClientMessageId } : {}),
+    },
   });
 }
 
@@ -2895,6 +2901,7 @@ class OpenCodeAgentSession implements AgentSession {
   /** Tracks the role of each message by ID to distinguish user from assistant messages */
   private messageRoles = new Map<string, OpenCodeMessageRole>();
   private pendingUserMessageText: string | null = null;
+  private pendingClientMessageId: string | null = null;
   private emittedUserMessageIds = new Set<string>();
   /** Tracks streamed textual part IDs to suppress final full-text echoes from OpenCode. */
   private streamedPartKeys = new Set<string>();
@@ -3103,6 +3110,7 @@ class OpenCodeAgentSession implements AgentSession {
 
     const parts = buildOpenCodePromptParts(prompt);
     this.pendingUserMessageText = buildOpenCodeUserTimelineText(prompt);
+    this.pendingClientMessageId = options?.clientMessageId ?? null;
     this.suppressAssistantMessagesUntilIdle.active = false;
     const model = this.parseModel(this.config.model);
     const thinkingOptionId = this.config.thinkingOptionId;
@@ -3645,6 +3653,7 @@ class OpenCodeAgentSession implements AgentSession {
     this.subAgentsByCallId.clear();
     this.subAgentCallIdByChildSessionId.clear();
     this.pendingUserMessageText = null;
+    this.pendingClientMessageId = null;
     this.abortController = null;
     this.notifySubscribers({ type: "turn_started", provider: "opencode" }, turnId);
     return turnId;
@@ -3670,6 +3679,7 @@ class OpenCodeAgentSession implements AgentSession {
       this.runningToolCalls.clear();
     }
     this.pendingUserMessageText = null;
+    this.pendingClientMessageId = null;
     this.activeForegroundTurnId = null;
     this.activeForegroundTurnSource = null;
     this.abortController = null;
@@ -4068,6 +4078,7 @@ class OpenCodeAgentSession implements AgentSession {
       cwd: this.config.cwd,
       messageRoles: this.messageRoles,
       pendingUserMessageText: this.pendingUserMessageText,
+      pendingClientMessageId: this.pendingClientMessageId,
       emittedUserMessageIds: this.emittedUserMessageIds,
       accumulatedUsage: this.accumulatedUsage,
       sessionTotalCostUsd: this.sessionTotalCostUsd,
diff --git a/packages/server/src/server/agent/providers/pi/agent.ts b/packages/server/src/server/agent/providers/pi/agent.ts
index 7a18f6ebb..e87ff42ec 100644
--- a/packages/server/src/server/agent/providers/pi/agent.ts
+++ b/packages/server/src/server/agent/providers/pi/agent.ts
@@ -258,6 +258,7 @@ interface PiCapturedEntry extends PiCapturedUserMessageEntry {
 interface PendingPiUserMessage {
   text: string;
   turnId: string | undefined;
+  clientMessageId?: string;
 }
 
 interface PendingExtensionResult {
@@ -1179,6 +1180,7 @@ export class PiRpcAgentSession implements AgentSession {
   private activeAskUserDialog: ActiveAskUserDialog | null = null;
   private pendingCombinedAskUserResponse: PendingCombinedAskUserResponse | null = null;
   private activeTurnId: string | null = null;
+  private activeClientMessageId: string | null = null;
   private activeAssistantMessageId: string | null = null;
   private activeTurnStarted = false;
   private activeNoTurnPromptText: string | null = null;
@@ -1240,7 +1242,7 @@ export class PiRpcAgentSession implements AgentSession {
     });
   }
 
-  async startTurn(prompt: AgentPromptInput, _options?: AgentRunOptions): Promise<StartTurnResult> {
+  async startTurn(prompt: AgentPromptInput, options?: AgentRunOptions): Promise<StartTurnResult> {
     if (this.activeTurnId) {
       throw new Error("A Pi turn is already active");
     }
@@ -1248,6 +1250,7 @@ export class PiRpcAgentSession implements AgentSession {
     const payload = convertPromptInput(prompt, { model: this.state.model });
     const turnId = randomUUID();
     this.activeTurnId = turnId;
+    this.activeClientMessageId = options?.clientMessageId ?? null;
     this.activeAssistantMessageId = null;
     this.activeTurnStarted = false;
     this.activePromptRequestId = null;
@@ -1278,6 +1281,7 @@ export class PiRpcAgentSession implements AgentSession {
           return;
         }
         this.activeTurnId = null;
+        this.activeClientMessageId = null;
         this.activeTurnStarted = false;
         this.activeAssistantMessageId = null;
         this.clearNoTurnBuffers();
@@ -1393,6 +1397,7 @@ export class PiRpcAgentSession implements AgentSession {
     await this.runtimeSession.abort();
     if (turnId && this.activeTurnId === turnId) {
       this.activeTurnId = null;
+      this.activeClientMessageId = null;
       this.activeTurnStarted = false;
       this.activeAssistantMessageId = null;
       this.clearNoTurnBuffers();
@@ -1574,6 +1579,7 @@ export class PiRpcAgentSession implements AgentSession {
         item: {
           type: "user_message",
           text: promptText,
+          ...(this.activeClientMessageId ? { clientMessageId: this.activeClientMessageId } : {}),
         },
       });
     }
@@ -1796,6 +1802,7 @@ export class PiRpcAgentSession implements AgentSession {
           type: "user_message",
           text: pending.text,
           messageId: entry.id,
+          ...(pending.clientMessageId ? { clientMessageId: pending.clientMessageId } : {}),
         },
       });
     }
@@ -1961,6 +1968,7 @@ export class PiRpcAgentSession implements AgentSession {
     }
     const turnId = this.activeTurnId;
     this.activeTurnId = null;
+    this.activeClientMessageId = null;
     this.activeTurnStarted = false;
     this.clearNoTurnBuffers();
     this.emit({
@@ -2170,7 +2178,11 @@ export class PiRpcAgentSession implements AgentSession {
     if (!text) {
       return;
     }
-    this.pendingUserMessages.push({ text, turnId });
+    this.pendingUserMessages.push({
+      text,
+      turnId,
+      ...(this.activeClientMessageId ? { clientMessageId: this.activeClientMessageId } : {}),
+    });
     void this.requestEntryCapture("message_end").catch((error: unknown) => {
       const message = error instanceof Error ? error.message : String(error);
       this.emit({
@@ -2221,6 +2233,7 @@ export class PiRpcAgentSession implements AgentSession {
 
   private completeTurn(turnId: string | undefined, messages: PiAgentMessage[]): void {
     this.activeTurnId = null;
+    this.activeClientMessageId = null;
     this.activeAssistantMessageId = null;
     this.activeTurnStarted = false;
     this.clearNoTurnBuffers();