geminixiang · Oct 9, 2026 · Oct 9, 2026 · Oct 9, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -11,6 +11,13 @@ change in a minor release.
 
 ## [Unreleased]
 
+### Fixed
+
+- `mikan migrate` step `0013-session-usage` no longer stops with
+  `Cannot read properties of undefined (reading 'input')` on an imported answer that recorded no
+  usage, and the Admin portal's daily usage chart no longer drops a session holding one; such
+  answers count as no spend.
+
 ## [1.3.0-beta.0]
 
 ### Added

diff --git a/src/sessions/session-store.ts b/src/sessions/session-store.ts
@@ -4,7 +4,7 @@ import { dirname } from "node:path";
 import type { AgentMessage } from "@earendil-works/pi-agent-core";
 import type { JsonValue } from "@earendil-works/chord";
 import { BACKGROUND_CONTEXT } from "@earendil-works/chord/context";
-import type { Message, Models, Usage } from "@earendil-works/pi-ai";
+import type { AssistantMessage, Message, Models, Usage } from "@earendil-works/pi-ai";
 import { calculateContextTokens } from "@earendil-works/pi-ai/utils/estimate";
 import {
   AssistantEntry,
@@ -687,7 +687,7 @@ async function importedUsage(
         record.conversationId !== conversationId ||
         record.byTaskId !== undefined ||
         !AssistantEntry.is(record) ||
-        message?.role !== "assistant"
+        !recordsUsage(message)
       ) {
         continue;
       }
@@ -701,6 +701,10 @@ async function importedUsage(
   return byModel;
 }
 
+function recordsUsage(message: AgentMessage | undefined): message is AssistantMessage {
+  return message?.role === "assistant" && isRecord(message.usage);
+}
+
 async function recordImportedUsage(
   harness: Harness,
   conversationId: ConversationId,
@@ -1035,7 +1039,7 @@ export class SessionStore implements SessionInspection {
       const id = session.conversation.id;
       return (await readRecords(session.conversation)).flatMap((record) => {
         const message = record.model?.[0];
-        return record.conversationId === id && message?.role === "assistant"
+        return record.conversationId === id && recordsUsage(message)
           ? [{ timestamp: message.timestamp, usage: message.usage }]
           : [];
       });

diff --git a/src/test/migrate-session-usage.test.ts b/src/test/migrate-session-usage.test.ts
@@ -1,3 +1,4 @@
+import type { AssistantMessage } from "@earendil-works/pi-ai";
 import { mkdtempSync, rmSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
@@ -42,10 +43,15 @@ function context(dryRun = false): MigrationContext {
   };
 }
 
-async function importedAnswer(key: string, input: number, cause?: string): Promise<void> {
+async function importedAnswer(
+  key: string,
+  input: number,
+  cause?: string,
+  withUsage = true,
+): Promise<void> {
   const session = await SessionStore.open(office, key);
   if (cause) await session.appendCustomEntry(RUN_CAUSE_CUSTOM_TYPE, { messageId: cause });
-  await session.appendMessage({
+  const answer: AssistantMessage = {
     role: "assistant",
     content: [{ type: "text", text: "imported answer" }],
     api: "openai-responses",
@@ -61,7 +67,9 @@ async function importedAnswer(key: string, input: number, cause?: string): Promi
     },
     stopReason: "stop",
     timestamp: 1,
-  });
+  };
+  if (!withUsage) Reflect.deleteProperty(answer, "usage");
+  await session.appendMessage(answer);
   await session.close();
 }
 
@@ -86,6 +94,16 @@ test("records the spend of imported answers once, and only in the session that h
   expect(await spentTokens("C1:1000.1")).toBe(0);
 });
 
+test("skips imported answers that recorded no usage", async () => {
+  await importedAnswer("C1", 10, undefined, false);
+  await importedAnswer("C1", 10);
+
+  await sessionUsageMigration.run(context());
+
+  expect(await spentTokens("C1")).toBe(12);
+  expect(await SessionStore.ownResponseUsage(office, "C1")).toHaveLength(1);
+});
+
 test("does nothing for an office without session storage", async () => {
   await sessionUsageMigration.run(context());
   expect(reports).toEqual([]);