feat(tui): improve session fork handling

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

@@ -17,6 +17,7 @@ import simplifyIntegrationCredentialsMigration from "@opencode-ai/core/database/
 import simplifySessionInputMigration from "@opencode-ai/core/database/migration/20260622202450_simplify_session_input"
 import resetSessionEventsMigration from "@opencode-ai/core/database/migration/20260703200000_reset_v2_session_events"
 import renameInstructionsMigration from "@opencode-ai/core/database/migration/20260705180000_rename_instructions"
+import addSessionForkMigration from "@opencode-ai/core/database/migration/20260706223930_add-session-fork"
 import { AppNodeBuilder } from "@opencode-ai/core/effect/app-node-builder"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { EventV2 } from "@opencode-ai/core/event"
@@ -156,6 +157,39 @@ describe("DatabaseMigration", () => {
     )
   })
 
+  test("separates existing fork provenance from subagent hierarchy", async () => {
+    await run(
+      Effect.gen(function* () {
+        const db = yield* makeDb
+        yield* db.run(sql`CREATE TABLE session (id text PRIMARY KEY, parent_id text)`)
+        yield* db.run(
+          sql`CREATE TABLE event (aggregate_id text NOT NULL, seq integer NOT NULL, type text NOT NULL, data text NOT NULL)`,
+        )
+        yield* db.run(sql`INSERT INTO session VALUES ('ses_source', NULL), ('ses_fork', 'ses_source')`)
+        yield* db.run(
+          sql`INSERT INTO event VALUES ('ses_fork', 0, 'session.forked', '{"sessionID":"ses_fork","parentID":"ses_source","from":"msg_boundary"}')`,
+        )
+
+        yield* DatabaseMigration.applyOnly(db, [addSessionForkMigration])
+
+        expect(
+          yield* db.get(sql`SELECT parent_id, fork_session_id, fork_message_id FROM session WHERE id = 'ses_fork'`),
+        ).toEqual({
+          parent_id: null,
+          fork_session_id: "ses_source",
+          fork_message_id: "msg_boundary",
+        })
+        expect(
+          yield* db.get(sql`SELECT parent_id, fork_session_id, fork_message_id FROM session WHERE id = 'ses_source'`),
+        ).toEqual({
+          parent_id: null,
+          fork_session_id: null,
+          fork_message_id: null,
+        })
+      }),
+    )
+  })
+
   test("renames instruction state without losing rows or durable updates", async () => {
     await run(
       Effect.gen(function* () {

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

@@ -206,7 +206,8 @@ describe("SessionV2.create", () => {
       const forkContext = yield* session.context(forked.id)
       const history = Array.from(yield* Stream.runCollect(logEvents(session, forked.id)))
 
-      expect(forked).toMatchObject({ parentID: parent.id, title: "Parent (fork #1)" })
+      expect(forked).toMatchObject({ title: "Parent (fork #1)", fork: { sessionID: parent.id } })
+      expect(forked.parentID).toBeUndefined()
       expect(forkContext).toMatchObject([
         { type: "user", text: "First" },
         { type: "synthetic", text: "parent note", sessionID: forked.id },
@@ -264,6 +265,7 @@ describe("SessionV2.create", () => {
 
       const context = yield* session.context(forked.id)
       const history = Array.from(yield* Stream.runCollect(logEvents(session, forked.id)))
+      expect(forked.fork).toEqual({ sessionID: parent.id, messageID: second.id })
       expect(context).toMatchObject([{ text: "First" }])
       expect(context[0]?.id).not.toBe(first.id)
       expect(history[0]).toMatchObject({ data: { from: second.id } })

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

@@ -283,25 +283,27 @@ describe("SessionV2.prompt", () => {
     }),
   )
 
-  it.effect("rejects directories as file attachments", () =>
+  it.effect("materializes directories as directory attachments", () =>
     Effect.gen(function* () {
       yield* setup
       const session = yield* SessionV2.Service
       const uri = pathToFileURL(import.meta.dir).href
 
-      const error = yield* session
-        .prompt({
-          sessionID,
-          prompt: { text: "Inspect this", files: [{ uri, name: "source" }] },
-          resume: false,
-        })
-        .pipe(Effect.flip)
-
-      expect(error).toMatchObject({
-        _tag: "Session.AttachmentError",
-        uri,
-        message: `Attachment is not a file: ${uri}`,
+      const message = yield* session.prompt({
+        sessionID,
+        prompt: { text: "Inspect this", files: [{ uri, name: "source" }] },
+        resume: false,
       })
+
+      expect(message.prompt.files).toHaveLength(1)
+      expect(message.prompt.files?.[0]).toMatchObject({
+        mime: "application/x-directory",
+        source: { type: "uri", uri },
+        name: "source",
+      })
+      expect(Buffer.from(message.prompt.files?.[0]?.data ?? "", "base64").toString("utf8")).toContain(
+        "session-prompt.test.ts",
+      )
     }),
   )
 

packages/core/test/session-runner-message.test.ts

@@ -217,6 +217,35 @@ Recent work
     ])
   })
 
+  test("lowers directory attachments as directory context", () => {
+    const directory = FileAttachment.make({
+      data: Base64.make(Buffer.from("lib/\nindex.ts").toString("base64")),
+      mime: "application/x-directory",
+      source: { type: "uri", uri: "file:///project/src" },
+      name: "src/",
+    })
+    const messages = toLLMMessages(
+      [
+        SessionMessage.User.make({
+          id: id("user-directory"),
+          type: "user",
+          text: "Review this directory",
+          files: [directory],
+          time: { created },
+        }),
+      ],
+      model,
+    )
+
+    expect(messages).toHaveLength(2)
+    expect(messages[0]).toMatchObject({
+      role: "user",
+      content: [{ type: "text", text: "Attached directory: src/\n\nlib/\nindex.ts" }],
+      metadata: { attachment: { source: directory.source, name: "src/" } },
+    })
+    expect(messages[1]?.content).toEqual([{ type: "text", text: "Review this directory" }])
+  })
+
   test("uses materialized image data as provider media and drops unsupported attachments", () => {
     const data = Base64.make("AAECAw==")
     const messages = toLLMMessages(