diff --git a/packages/core/src/services/conversationRecordSchema.ts b/packages/core/src/services/conversationRecordSchema.ts
new file mode 100644
index 0000000000..29d8ce3c7f
--- /dev/null
+++ b/packages/core/src/services/conversationRecordSchema.ts
@@ -0,0 +1,341 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { z } from 'zod';
+import { CoreToolCallStatus } from '../scheduler/types.js';
+import { AgentTerminateMode } from '../agents/types.js';
+import { Language, Outcome } from '@google/genai';
+import type { TokensSummary, ToolCallRecord } from './chatRecordingService.js';
+import type { ToolResultDisplay } from '../tools/tools.js';
+
+const nonEmptyStringSchema = z.string().min(1);
+
+const todoStatusSchema = z.enum([
+  'pending',
+  'in_progress',
+  'completed',
+  'cancelled',
+  'blocked',
+]);
+
+const subagentActivityStatusSchema = z.enum([
+  'running',
+  'completed',
+  'error',
+  'cancelled',
+]);
+
+const subagentProgressStateSchema = z.enum([
+  'running',
+  'completed',
+  'error',
+  'cancelled',
+]);
+
+const diffStatSchema = z
+  .object({
+    model_added_lines: z.number(),
+    model_removed_lines: z.number(),
+    model_added_chars: z.number(),
+    model_removed_chars: z.number(),
+    user_added_lines: z.number(),
+    user_removed_lines: z.number(),
+    user_added_chars: z.number(),
+    user_removed_chars: z.number(),
+  })
+  .strict();
+
+const fileDiffSchema = z
+  .object({
+    fileDiff: nonEmptyStringSchema,
+    fileName: nonEmptyStringSchema,
+    filePath: nonEmptyStringSchema,
+    originalContent: z.string().nullable(),
+    newContent: z.string(),
+    diffStat: diffStatSchema.optional(),
+    isNewFile: z.boolean().optional(),
+  })
+  .strict();
+
+const ansiTokenSchema = z
+  .object({
+    text: z.string(),
+    bold: z.boolean(),
+    italic: z.boolean(),
+    underline: z.boolean(),
+    dim: z.boolean(),
+    inverse: z.boolean(),
+    fg: z.string(),
+    bg: z.string(),
+  })
+  .strict();
+
+const ansiOutputSchema = z.array(z.array(ansiTokenSchema));
+
+const todoSchema = z
+  .object({
+    description: z.string(),
+    status: todoStatusSchema,
+  })
+  .strict();
+
+const todoListSchema = z
+  .object({
+    todos: z.array(todoSchema),
+  })
+  .strict();
+
+const subagentActivityItemSchema = z
+  .object({
+    id: nonEmptyStringSchema,
+    type: z.enum(['thought', 'tool_call']),
+    content: z.string(),
+    displayName: z.string().optional(),
+    description: z.string().optional(),
+    args: z.string().optional(),
+    status: subagentActivityStatusSchema,
+  })
+  .strict();
+
+const subagentProgressSchema = z
+  .object({
+    isSubagentProgress: z.literal(true),
+    agentName: nonEmptyStringSchema,
+    recentActivity: z.array(subagentActivityItemSchema),
+    state: subagentProgressStateSchema.optional(),
+    result: z.string().optional(),
+    terminateReason: z.nativeEnum(AgentTerminateMode).optional(),
+  })
+  .strict();
+
+const grepResultSchema = z
+  .object({
+    summary: z.string(),
+    matches: z.array(z.unknown()),
+    payload: z.string().optional(),
+  })
+  .strict();
+
+const listDirectoryResultSchema = z
+  .object({
+    summary: z.string(),
+    files: z.array(z.string()),
+    payload: z.string().optional(),
+  })
+  .strict();
+
+const readManyFilesResultSchema = z
+  .object({
+    summary: z.string(),
+    files: z.array(z.string()),
+    skipped: z
+      .array(
+        z.object({
+          path: z.string(),
+          reason: z.string(),
+        })
+      )
+      .optional(),
+    include: z.array(z.string()).optional(),
+    excludes: z.array(z.string()).optional(),
+    targetDir: z.string().optional(),
+    payload: z.string().optional(),
+  })
+  .strict();
+
+export const toolResultDisplaySchema: z.ZodType<ToolResultDisplay> = z.union([
+  z.string(),
+  fileDiffSchema,
+  ansiOutputSchema,
+  todoListSchema,
+  subagentProgressSchema,
+  grepResultSchema,
+  listDirectoryResultSchema,
+  readManyFilesResultSchema,
+]);
+
+const inlineDataSchema = z
+  .object({
+    data: z.string(),
+    mimeType: z.string().optional(),
+  })
+  .strict();
+
+const fileDataSchema = z
+  .object({
+    fileUri: z.string(),
+    mimeType: z.string().optional(),
+  })
+  .strict();
+
+const functionCallSchema = z
+  .object({
+    name: nonEmptyStringSchema,
+    id: z.string().optional(),
+    args: z.record(z.unknown()).optional(),
+  })
+  .strict();
+
+const executableCodeSchema = z
+  .object({
+    code: z.string(),
+    language: z.nativeEnum(Language).optional(),
+  })
+  .strict();
+
+const codeExecutionResultSchema = z
+  .object({
+    outcome: z.nativeEnum(Outcome).optional(),
+    output: z.string().optional(),
+  })
+  .strict()
+  .refine(
+    (result) => result.outcome !== undefined || result.output !== undefined,
+    {
+      message:
+        'codeExecutionResult must include at least one of outcome or output.',
+    }
+  );
+
+const thoughtSummaryWithTimestampSchema = z
+  .object({
+    subject: z.string(),
+    description: z.string(),
+    timestamp: nonEmptyStringSchema,
+  })
+  .strict();
+
+let partObjectSchema: z.ZodTypeAny;
+
+const partItemSchema = z.lazy(() =>
+  z.union([z.string(), partObjectSchema])
+);
+
+partObjectSchema = z.lazy(() =>
+  z
+    .object({
+      text: z.string().optional(),
+      thought: z.boolean().optional(),
+      thoughtSignature: z.string().optional(),
+      inlineData: inlineDataSchema.optional(),
+      fileData: fileDataSchema.optional(),
+      functionCall: functionCallSchema.optional(),
+      functionResponse: z
+        .object({
+          name: nonEmptyStringSchema,
+          id: z.string().optional(),
+          response: z.unknown(),
+          parts: z.array(partItemSchema).optional(),
+        })
+        .strict()
+        .optional(),
+      executableCode: executableCodeSchema.optional(),
+      codeExecutionResult: codeExecutionResultSchema.optional(),
+      videoMetadata: z.unknown().optional(),
+    })
+    .strict()
+    .refine(
+      (part) =>
+        part.text !== undefined ||
+        part.thought === true ||
+        part.thoughtSignature !== undefined ||
+        part.inlineData !== undefined ||
+        part.fileData !== undefined ||
+        part.functionCall !== undefined ||
+        part.functionResponse !== undefined ||
+        part.executableCode !== undefined ||
+        part.codeExecutionResult !== undefined ||
+        part.videoMetadata !== undefined,
+      {
+        message:
+          'Part must include at least one meaningful content field.',
+      }
+    )
+);
+
+export const partListUnionSchema: z.ZodTypeAny = z.union([
+  z.string(),
+  partObjectSchema,
+  z.array(partItemSchema),
+]);
+
+const toolCallStatusSchema = z.nativeEnum(CoreToolCallStatus);
+
+export const tokensSummarySchema: z.ZodType<TokensSummary> = z
+  .object({
+    input: z.number(),
+    output: z.number(),
+    cached: z.number(),
+    thoughts: z.number().optional(),
+    tool: z.number().optional(),
+    total: z.number(),
+  })
+  .strict();
+
+export const toolCallRecordSchema: z.ZodType<ToolCallRecord> = z
+  .object({
+    id: nonEmptyStringSchema,
+    name: nonEmptyStringSchema,
+    args: z.record(z.unknown()),
+    result: partListUnionSchema.nullable().optional(),
+    status: toolCallStatusSchema,
+    timestamp: nonEmptyStringSchema,
+    displayName: z.string().optional(),
+    description: z.string().optional(),
+    resultDisplay: toolResultDisplaySchema.optional(),
+    renderOutputAsMarkdown: z.boolean().optional(),
+  })
+  .strict();
+
+const baseMessageRecordSchema = z
+  .object({
+    id: nonEmptyStringSchema,
+    timestamp: nonEmptyStringSchema,
+    content: partListUnionSchema,
+    displayContent: partListUnionSchema.optional(),
+  })
+  .strict();
+
+const userLikeMessageRecordSchema = baseMessageRecordSchema
+  .extend({
+    type: z.enum(['user', 'info', 'error', 'warning']),
+  })
+  .strict();
+
+const geminiMessageRecordSchema = baseMessageRecordSchema
+  .extend({
+    type: z.literal('gemini'),
+    toolCalls: z.array(toolCallRecordSchema).optional(),
+    thoughts: z.array(thoughtSummaryWithTimestampSchema).optional(),
+    tokens: tokensSummarySchema.nullable().optional(),
+    model: z.string().optional(),
+  })
+  .strict();
+
+export const messageRecordSchema = z.discriminatedUnion('type', [
+  userLikeMessageRecordSchema,
+  geminiMessageRecordSchema,
+]);
+
+export const conversationRecordSchema = z
+  .object({
+    sessionId: nonEmptyStringSchema,
+    projectHash: nonEmptyStringSchema,
+    startTime: nonEmptyStringSchema,
+    lastUpdated: nonEmptyStringSchema,
+    messages: z.array(messageRecordSchema),
+    summary: z.string().optional(),
+    directories: z.array(z.string()).optional(),
+    kind: z.enum(['main', 'subagent']).optional(),
+  })
+  .strict();
+
+export type ConversationRecordSchemaType = z.infer<
+  typeof conversationRecordSchema
+>;
+export type MessageRecordSchemaType = z.infer<typeof messageRecordSchema>;
+export type ToolCallRecordSchemaType = z.infer<typeof toolCallRecordSchema>;
+export type TokensSummarySchemaType = z.infer<typeof tokensSummarySchema>;
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