feat(session): make generated titles optional (#39747)

packages/core/test/database-migration.test.ts

@@ -26,6 +26,7 @@ import timeSuspendedMigration from "@opencode-ai/core/database/migration/2026070
 import instructionSyncMigration from "@opencode-ai/core/database/migration/20260710025429_instruction_sync"
 import deleteToolProgressEventsMigration from "@opencode-ai/core/database/migration/20260722011141_delete_tool_progress_events"
 import canonicalToolResultsMigration from "@opencode-ai/core/database/migration/20260722170000_canonical_tool_results"
+import optionalSessionTitleMigration from "@opencode-ai/core/database/migration/20260730195856_optional_session_title"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { LayerNode } from "@opencode-ai/util/effect/layer-node"
 import { Bus } from "@opencode-ai/core/bus"
@@ -399,6 +400,40 @@ describe("DatabaseMigration", () => {
     ).rejects.toThrow("Database is not empty and has no session table")
   })
 
+  test("makes session titles nullable without deleting dependent rows", async () => {
+    await run(
+      Effect.gen(function* () {
+        const db = yield* makeDb
+        yield* db.run(sql`PRAGMA foreign_keys = ON`)
+        yield* db.run(sql`
+          CREATE TABLE session (
+            id text PRIMARY KEY,
+            title text NOT NULL
+          )
+        `)
+        yield* db.run(sql`
+          CREATE TABLE message (
+            id text PRIMARY KEY,
+            session_id text NOT NULL REFERENCES session(id) ON DELETE CASCADE
+          )
+        `)
+        yield* db.run(sql`INSERT INTO session VALUES ('ses_existing', 'Existing title')`)
+        yield* db.run(sql`INSERT INTO message VALUES ('msg_existing', 'ses_existing')`)
+
+        yield* DatabaseMigration.applyOnly(db, [optionalSessionTitleMigration])
+
+        expect(yield* db.get(sql`SELECT title FROM session WHERE id = 'ses_existing'`)).toEqual({
+          title: "Existing title",
+        })
+        expect(yield* db.get(sql`SELECT id FROM message WHERE id = 'msg_existing'`)).toEqual({ id: "msg_existing" })
+        expect(
+          yield* db.get<{ notnull: number }>(sql`SELECT "notnull" FROM pragma_table_info('session') WHERE name = 'title'`),
+        ).toEqual({ notnull: 0 })
+        expect(yield* db.get<{ foreign_keys: number }>(sql`PRAGMA foreign_keys`)).toEqual({ foreign_keys: 1 })
+      }),
+    )
+  })
+
   test("backfills existing Context Epoch rows to the build agent", async () => {
     await run(
       Effect.gen(function* () {

packages/core/test/session-create.test.ts

@@ -71,6 +71,27 @@ function withTmp<A, E, R>(f: (directory: string) => Effect.Effect<A, E, R>) {
 }
 
 describe("Session.create", () => {
+  it.effect("persists a missing title until one is generated or supplied", () =>
+    Effect.gen(function* () {
+      const session = yield* Session.Service
+      const { db } = yield* Database.Service
+
+      const created = yield* session.create({ location })
+      const row = yield* db.select().from(SessionTable).where(eq(SessionTable.id, created.id)).get().pipe(Effect.orDie)
+      const event = yield* db
+        .select({ data: EventTable.data })
+        .from(EventTable)
+        .where(eq(EventTable.aggregate_id, created.id))
+        .get()
+        .pipe(Effect.orDie)
+
+      expect(created.title).toBeUndefined()
+      expect(row?.title).toBeNull()
+      expect(event?.data).not.toHaveProperty("info.title")
+      expect((yield* session.create({ location, title: "Explicit title" })).title).toBe("Explicit title")
+    }),
+  )
+
   it.effect("creates a fresh projected session when the ID is omitted", () =>
     Effect.gen(function* () {
       const session = yield* Session.Service
@@ -296,6 +317,23 @@ describe("Session.create", () => {
     }),
   )
 
+  it.effect("keeps a fork untitled when its parent is untitled", () =>
+    Effect.gen(function* () {
+      const session = yield* Session.Service
+      const bus = yield* Bus.Service
+      const { db } = yield* Database.Service
+      const parent = yield* session.create({ location })
+      yield* session.prompt({ sessionID: parent.id, text: "First", resume: false })
+      yield* SessionPending.promote(db, bus, parent.id, "steer")
+
+      const forked = yield* session.fork({ sessionID: parent.id, boundary: { type: "through" } })
+      const row = yield* db.select().from(SessionTable).where(eq(SessionTable.id, forked.id)).get().pipe(Effect.orDie)
+
+      expect(forked.title).toBeUndefined()
+      expect(row?.title).toBeNull()
+    }),
+  )
+
   it.effect("rejects forking an empty session", () =>
     Effect.gen(function* () {
       const session = yield* Session.Service

packages/core/test/tool-subagent.test.ts

@@ -47,7 +47,7 @@ const executionNode = makeGlobalNode({
       const completed = new Set<Session.ID>()
       const complete = Effect.fn("SubagentTest.complete")(function* (sessionID: Session.ID) {
         if (completed.has(sessionID)) return
-        if ((yield* store.get(sessionID))?.title.includes("fail")) {
+        if ((yield* store.get(sessionID))?.title?.includes("fail")) {
           yield* new SessionRunnerModel.ModelNotSelectedError({ sessionID })
           return
         }