diff --git a/packages/session-persistence/session-persistence-sqlite/README.md b/packages/session-persistence/session-persistence-sqlite/README.md
index 6dcfa2d125..95256edb88 100644
--- a/packages/session-persistence/session-persistence-sqlite/README.md
+++ b/packages/session-persistence/session-persistence-sqlite/README.md
@@ -10,7 +10,7 @@ A SQLite durable session-persistence backend — a second `SessionPersistence` i
 
 Each `SessionEvent` maps 1:1 onto a row in an `events` table `(session_id, seq, type, time, data, source_event_seqs, surface_op)` — `data` is the event payload as JSON text, so the row shape is the event verbatim (including `assistant/chunk`, keeping `seq` contiguous). The two `TEXT` columns `source_event_seqs` and `surface_op` are nullable; they store the event's optional surface-metadata fields (see [session surface](../../../.agents/notes/implemented/architecture/2026-06-18-session-surface.md)). Out-of-log metadata (`SessionHeader`), a per-materialization incarnation id, and a monotonic per-log revision live in a `sessions` row; a singleton state row carries the immutable store id. A `sessions` row is written only by the first `append` — its existence is the lazy-materialization signal (`list` reports exactly the sessions that have a row).
 
-The repository's Node range supports unflagged `node:sqlite`. The database enables foreign keys and uses the configured journal mode (`wal` by default; use a rollback mode where WAL shared-memory files are unsuitable). `PRAGMA user_version` stores the table-layout version; databases with any other version are rejected because this unreleased format has no migrations.
+The repository's Node range supports unflagged `node:sqlite`. The database enables foreign keys and uses the configured journal mode (`wal` by default; use a rollback mode where WAL shared-memory files are unsuitable). `PRAGMA user_version` stores the table-layout version. A fresh empty database is initialized at the current version; nonempty unversioned databases and every other version are rejected because this unreleased format has no migrations. Rejection occurs before changing journal mode or stamping the file.
 
 On filesystems with POSIX modes, the backend requests mode `0700` for missing directories and exclusively creates a missing database with mode `0600` before SQLite opens it; the process umask may further restrict both. New WAL, shared-memory, and persistent rollback-journal sidecars receive the database's resulting owner-only mode. Existing directories, database files, and sidecars keep their modes; filesystem setup errors other than an existing database fail initialization. These defaults prevent incidental exposure through a permissive process umask, but do not protect database confidentiality or integrity when another principal can replace the database entry in its parent directory.
 
@@ -55,5 +55,5 @@ SQLite storage does not mutate live request prefixes. A resumed loop can reuse p
 
 - **`DatabaseSync` is synchronous** — every append transaction blocks the event loop for its duration; acceptable for local stores, a throughput ceiling for busy multi-session servers.
 - **Write contention has no wait or retry policy** — the backend sets no busy timeout and retries no locked-database error, so another connection holding a write transaction makes the operation reject immediately.
-- **Only the current `SCHEMA_VERSION` opens** — a database with any other schema version is rejected rather than migrated (unreleased software; no persisted user data to preserve).
+- **Only an empty new database or the current `SCHEMA_VERSION` opens** — a nonempty unversioned database or any other schema version is rejected rather than migrated (unreleased software; no persisted user data to preserve).
 - **Nothing deletes stored sessions** — rows accumulate until removed externally (the seam has no deletion surface; `ON DELETE CASCADE` is wired for such out-of-band cleanup).
diff --git a/packages/session-persistence/session-persistence-sqlite/src/schema.ts b/packages/session-persistence/session-persistence-sqlite/src/schema.ts
index 8b8dcd78e0..a89b691213 100644
--- a/packages/session-persistence/session-persistence-sqlite/src/schema.ts
+++ b/packages/session-persistence/session-persistence-sqlite/src/schema.ts
@@ -17,7 +17,7 @@ import type { SessionEvent, SessionId, SessionHeader, SurfaceOp } from '@deepsee
  * layout; orthogonal to a session's own `version` (which versions the EVENT
  * vocabulary, stored per session in the `sessions` row).
  */
-export const SCHEMA_VERSION = 8
+export const SCHEMA_VERSION = 9
 
 /**
  * A row of the `sessions` table — the out-of-log metadata ({@link SessionHeader}).
@@ -63,9 +63,10 @@ export interface EventRow {
 export type JournalMode = 'wal' | 'delete' | 'truncate' | 'persist'
 
 /**
- * Open the database and apply its schema and pragmas. A zero `user_version` is
- * stamped with {@link SCHEMA_VERSION}; every other non-current version rejects
- * rather than being migrated in place.
+ * Open the database and apply its schema and pragmas. An empty database with a
+ * zero `user_version` is initialized at {@link SCHEMA_VERSION}; a nonempty
+ * unversioned database and every other non-current version reject rather than
+ * being migrated in place.
  * @param path - the SQLite database file to open (created when absent).
  * @param journalMode - validated journal pragma.
  * @returns the open handle with pragmas applied and all three tables ensured.
@@ -83,17 +84,20 @@ export function openDatabase(path: string, journalMode: JournalMode): DatabaseSy
 
 function configureDatabase(db: DatabaseSync, path: string, journalMode: JournalMode): void {
   db.exec('PRAGMA foreign_keys = ON')
-  // The validated union is safe to interpolate into a non-bindable PRAGMA.
-  db.exec(`PRAGMA journal_mode = ${journalMode.toUpperCase()}`)
   // `PRAGMA user_version` always returns exactly one row { user_version }.
   const { user_version: onDisk } = db.prepare('PRAGMA user_version').get() as { user_version: number }
+  const { count: userTableCount } = db.prepare(
+    "SELECT COUNT(*) AS count FROM sqlite_schema WHERE type = 'table' AND name NOT LIKE 'sqlite_%'",
+  ).get() as { count: number }
+  if (onDisk === 0 && userTableCount > 0) {
+    throw new Error(`session database at "${path}" has a nonempty unversioned schema`)
+  }
   if (onDisk !== 0 && onDisk !== SCHEMA_VERSION) {
     throw new Error(`session database at "${path}" has schema version ${onDisk}, incompatible with this build (${SCHEMA_VERSION})`)
   }
-  if (onDisk === 0) {
-    // Stamp fresh or pre-versioning databases.
-    db.exec(`PRAGMA user_version = ${SCHEMA_VERSION}`)
-  }
+  // The validated union is safe to interpolate into a non-bindable PRAGMA.
+  // Apply it only after rejecting incompatible existing databases.
+  db.exec(`PRAGMA journal_mode = ${journalMode.toUpperCase()}`)
   db.exec(`
     CREATE TABLE IF NOT EXISTS persistence_state (
       singleton INTEGER PRIMARY KEY CHECK (singleton = 1),
@@ -107,7 +111,7 @@ function configureDatabase(db: DatabaseSync, path: string, journalMode: JournalM
     CREATE TABLE IF NOT EXISTS sessions (
       id             TEXT PRIMARY KEY,
       version        INTEGER NOT NULL,
-      created_at     INTEGER NOT NULL,
+      created_at     REAL NOT NULL,
       cwd              TEXT,
       parent_session   TEXT,
       seed_length      INTEGER,
@@ -128,6 +132,7 @@ function configureDatabase(db: DatabaseSync, path: string, journalMode: JournalM
       PRIMARY KEY (session_id, seq)
     ) STRICT
   `)
+  if (onDisk === 0) db.exec(`PRAGMA user_version = ${SCHEMA_VERSION}`)
 }
 
 /**
diff --git a/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts b/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
index 3976e71549..fe8fdfb0cf 100644
--- a/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
+++ b/packages/session-persistence/session-persistence-sqlite/tests/sqlite.spec.ts
@@ -4,6 +4,7 @@ import { existsSync } from 'node:fs'
 import { chmod, mkdtemp, rm, stat, symlink, writeFile } from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { dirname, join } from 'node:path'
+import { DatabaseSync } from 'node:sqlite'
 import SessionStore, { SessionId } from '@deepseek-ai/dsh-session'
 import type { Session, SessionEvent, SurfaceEvent, SurfaceEventType } from '@deepseek-ai/dsh-session'
 import SessionPersistenceSqlite, { SCHEMA_VERSION } from '@deepseek-ai/dsh-session-persistence-sqlite'
@@ -304,6 +305,23 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
     expect(() => openDatabase(olderPath, 'wal')).toThrow(/incompatible with this build/)
   })
 
+  it('rejects a nonempty unversioned database before stamping or changing journal mode', async () => {
+    const path = await freshDbPath()
+    const legacy = new DatabaseSync(path)
+    legacy.exec('CREATE TABLE sessions (id TEXT PRIMARY KEY)')
+    legacy.close()
+
+    expect(() => openDatabase(path, 'wal')).toThrow(/nonempty unversioned schema/)
+
+    const unchanged = new DatabaseSync(path)
+    expect(unchanged.prepare('PRAGMA user_version').get()).toEqual({ user_version: 0 })
+    expect(unchanged.prepare('PRAGMA journal_mode').get()).toEqual({ journal_mode: 'delete' })
+    expect(unchanged.prepare(
+      "SELECT name FROM sqlite_schema WHERE type = 'table' AND name = 'sessions'",
+    ).get()).toEqual({ name: 'sessions' })
+    unchanged.close()
+  })
+
   it('rejects a sibling v3 database (the merge-collided version) rather than opening it against missing columns', async () => {
     // Version 3 identified two incompatible sibling layouts, so it is always rejected.
     const path = await freshDbPath()
@@ -442,7 +460,7 @@ describe('SessionPersistenceSqlite: durability and crash semantics', () => {
   })
 
   it('exposes the schema version constant', () => {
-    expect(SCHEMA_VERSION).toBe(8)
+    expect(SCHEMA_VERSION).toBe(9)
   })
 
   it('keeps the revision stable for an empty repair hook', async () => {
diff --git a/packages/session-persistence/session-persistence/tests/contract.ts b/packages/session-persistence/session-persistence/tests/contract.ts
index ae07bf77aa..c5ccca7c0d 100644
--- a/packages/session-persistence/session-persistence/tests/contract.ts
+++ b/packages/session-persistence/session-persistence/tests/contract.ts
@@ -84,6 +84,20 @@ export function runPersistenceContract(name: string, make: () => Promise<Contrac
       }
     })
 
+    it('round-trips a finite fractional creation timestamp', async () => {
+      const { persistence, dispose } = await make()
+      try {
+        const m = { ...meta('fractional-created-at'), createdAt: 1.5 }
+        await persistence.create(m)
+        await persistence.append(m.id, oneTurnLog())
+
+        const loaded = await persistence.load(m.id)
+        expect(loaded.meta.createdAt).toBe(1.5)
+      } finally {
+        await dispose()
+      }
+    })
+
     it('crash recovery: load preserves an interrupted (unclosed) turn and closes it with turn/end {interrupted}', async () => {
       const { persistence, dispose } = await make()
       try {
diff --git a/packages/session-query/session-query-sqlite/src/schema.ts b/packages/session-query/session-query-sqlite/src/schema.ts
index b88e04b536..0cb423e582 100644
--- a/packages/session-query/session-query-sqlite/src/schema.ts
+++ b/packages/session-query/session-query-sqlite/src/schema.ts
@@ -5,7 +5,7 @@ import { mkdir, open } from 'node:fs/promises'
 import { dirname, resolve } from 'node:path'
 
 /** Current derived-index schema version. Incompatible versions reset in place. */
-export const SESSION_QUERY_SQLITE_SCHEMA_VERSION = 3
+export const SESSION_QUERY_SQLITE_SCHEMA_VERSION = 4
 
 /** SQLite application id protecting unrelated databases from derived resets. */
 export const SESSION_QUERY_SQLITE_APPLICATION_ID = 0x44534851
@@ -112,7 +112,7 @@ function ensurePersistentSchema(db: DatabaseSync): void {
     CREATE TABLE IF NOT EXISTS persisted_sessions (
       id             TEXT PRIMARY KEY,
       version        INTEGER NOT NULL,
-      created_at     INTEGER NOT NULL,
+      created_at     REAL NOT NULL,
       cwd            TEXT,
       parent_session TEXT,
       seed_length    INTEGER,
@@ -141,7 +141,7 @@ function ensureTemporarySchema(db: DatabaseSync): void {
     CREATE TEMP TABLE IF NOT EXISTS live_sessions (
       id             TEXT PRIMARY KEY,
       version        INTEGER NOT NULL,
-      created_at     INTEGER NOT NULL,
+      created_at     REAL NOT NULL,
       cwd            TEXT,
       parent_session TEXT,
       seed_length    INTEGER,
diff --git a/packages/session-query/session-query-sqlite/tests/sqlite.spec.ts b/packages/session-query/session-query-sqlite/tests/sqlite.spec.ts
index 1923c6f3eb..a886f54bd4 100644
--- a/packages/session-query/session-query-sqlite/tests/sqlite.spec.ts
+++ b/packages/session-query/session-query-sqlite/tests/sqlite.spec.ts
@@ -167,6 +167,22 @@ async function liveContext(config: ConstructorParameters<typeof SessionQuerySqli
 }
 
 describe('SQLite session search', () => {
+  it('indexes finite fractional creation timestamps from live and persisted sources', async () => {
+    const persisted = header('fractional-persisted', 1.5)
+    TestPersistence.reset([{ meta: persisted, events: messageEvents('persisted fractional') }])
+    const ctx = await liveContext()
+    await ctx.plugin(TestPersistence)
+    const live = ctx.sessions.create(SessionId('fractional-live'), {
+      seed: messageEvents('live fractional'),
+      meta: { createdAt: 2.5 },
+    })
+
+    await expect(ctx.sessionQuery.searchSessions({ query: 'persisted' }))
+      .resolves.toMatchObject({ items: [{ header: { id: persisted.id, createdAt: 1.5 } }] })
+    await expect(ctx.sessionQuery.searchSessions({ query: 'live' }))
+      .resolves.toMatchObject({ items: [{ header: { id: live.id, createdAt: 2.5 } }] })
+  })
+
   it('searches two-character Unicode61 tokens in live-only sessions', async () => {
     const ctx = await liveContext({ path: ':memory:', snippetChars: 20 })
     const session = ctx.sessions.create(SessionId('live'), {