feat(storage): add read-only thread store doctor

kun/src/contracts/index.ts

@@ -16,3 +16,4 @@ export * from './tool-output-limits.js'
 export * from './memory.js'
 export * from './model-endpoint-format.js'
 export * from './extension-providers.js'
+export * from './thread-store-diagnostics.js'

kun/src/contracts/thread-store-diagnostics.ts

@@ -0,0 +1,48 @@
+import { z } from 'zod'
+
+/**
+ * Result of checking one persisted thread without changing any files.
+ *
+ * The doctor deliberately reports each storage surface independently. A
+ * missing SQLite index is recoverable from JSONL, while invalid event data is
+ * not something a repair pass may silently reconstruct.
+ */
+export const ThreadStoreArtifactStatus = z.enum([
+  'ok',
+  'missing',
+  'invalid',
+  'truncated',
+  'mismatch'
+])
+export type ThreadStoreArtifactStatus = z.infer<typeof ThreadStoreArtifactStatus>
+
+export const ThreadStoreDiagnosticSeverity = z.enum(['warning', 'error'])
+export type ThreadStoreDiagnosticSeverity = z.infer<typeof ThreadStoreDiagnosticSeverity>
+
+export const ThreadStoreDiagnosticIssue = z.object({
+  // Diagnostics must remain safe to render and export even when a parser
+  // reports data copied from a damaged log line.
+  code: z.string().min(1).max(128),
+  message: z.string().min(1).max(1024),
+  severity: ThreadStoreDiagnosticSeverity
+}).strict()
+export type ThreadStoreDiagnosticIssue = z.infer<typeof ThreadStoreDiagnosticIssue>
+
+export const ThreadStoreDiagnostic = z.object({
+  threadId: z.string().min(1).max(256),
+  metadata: ThreadStoreArtifactStatus,
+  events: ThreadStoreArtifactStatus,
+  sqliteIndex: ThreadStoreArtifactStatus,
+  attachments: ThreadStoreArtifactStatus,
+  recoverable: z.boolean(),
+  issues: z.array(ThreadStoreDiagnosticIssue).max(64),
+  checkedAt: z.string().datetime({ offset: true })
+}).strict()
+export type ThreadStoreDiagnostic = z.infer<typeof ThreadStoreDiagnostic>
+
+export const ThreadStoreDiagnosticReport = z.object({
+  schemaVersion: z.literal(1),
+  checkedAt: z.string().datetime({ offset: true }),
+  threads: z.array(ThreadStoreDiagnostic)
+}).strict()
+export type ThreadStoreDiagnosticReport = z.infer<typeof ThreadStoreDiagnosticReport>

kun/src/services/index.ts

@@ -13,3 +13,4 @@ export * from './extension-host-broker.js'
 export * from './extension-secret-reveal-consent.js'
 export * from './extension-configuration-service.js'
 export * from './extension-view-session-service.js'
+export * from './thread-store-doctor.js'