diff --git a/packages/core/src/database/migration.gen.ts b/packages/core/src/database/migration.gen.ts
index 1e915bb3cf6..3996a8f295b 100644
--- a/packages/core/src/database/migration.gen.ts
+++ b/packages/core/src/database/migration.gen.ts
@@ -37,5 +37,6 @@ export const migrations = (
     import("./migration/20260611035744_credential"),
     import("./migration/20260611192811_lush_chimera"),
     import("./migration/20260612174303_project_dir_strategy"),
+    import("./migration/20260613210000_backfill_project_copy_strategy"),
   ])
 ).map((module) => module.default) satisfies DatabaseMigration.Migration[]
diff --git a/packages/core/src/database/migration/20260613210000_backfill_project_copy_strategy.ts b/packages/core/src/database/migration/20260613210000_backfill_project_copy_strategy.ts
new file mode 100644
index 00000000000..9c2afeb188f
--- /dev/null
+++ b/packages/core/src/database/migration/20260613210000_backfill_project_copy_strategy.ts
@@ -0,0 +1,13 @@
+import { Effect } from "effect"
+import type { DatabaseMigration } from "../migration"
+
+export default {
+  id: "20260613210000_backfill_project_copy_strategy",
+  up(tx) {
+    return Effect.gen(function* () {
+      yield* tx.run(
+        `UPDATE \`project_directory\` SET \`strategy\` = 'git_worktree' WHERE \`type\` = 'git_worktree' AND \`strategy\` IS NULL;`,
+      )
+    })
+  },
+} satisfies DatabaseMigration.Migration
diff --git a/packages/core/test/database-migration.test.ts b/packages/core/test/database-migration.test.ts
index d7126f76e26..f2fe0e3f3d3 100644
--- a/packages/core/test/database-migration.test.ts
+++ b/packages/core/test/database-migration.test.ts
@@ -14,6 +14,7 @@ import sessionMessageProjectionOrderMigration from "@opencode-ai/core/database/m
 import eventSourcedSessionInputMigration from "@opencode-ai/core/database/migration/20260604172448_event_sourced_session_input"
 import contextEpochAgentMigration from "@opencode-ai/core/database/migration/20260605042240_add_context_epoch_agent"
 import simplifyIntegrationCredentialsMigration from "@opencode-ai/core/database/migration/20260611192811_lush_chimera"
+import backfillProjectCopyStrategyMigration from "@opencode-ai/core/database/migration/20260613210000_backfill_project_copy_strategy"
 import { ProjectV2 } from "@opencode-ai/core/project"
 import { ProjectTable } from "@opencode-ai/core/project/sql"
 import { AbsolutePath } from "@opencode-ai/core/schema"
@@ -150,6 +151,29 @@ describe("DatabaseMigration", () => {
     )
   })
 
+  test("backfills strategies for legacy project copies", async () => {
+    await run(
+      Effect.gen(function* () {
+        const db = yield* makeDb
+        yield* db.run(
+          sql`CREATE TABLE project_directory (project_id text NOT NULL, directory text NOT NULL, type text, strategy text, time_created integer NOT NULL, PRIMARY KEY (project_id, directory))`,
+        )
+        yield* db.run(
+          sql`INSERT INTO project_directory (project_id, directory, type, strategy, time_created) VALUES ('project', '/root', 'main', NULL, 1), ('project', '/copy', 'git_worktree', NULL, 2)`,
+        )
+
+        yield* DatabaseMigration.applyOnly(db, [backfillProjectCopyStrategyMigration])
+
+        expect(
+          yield* db.all(sql`SELECT directory, strategy FROM project_directory ORDER BY directory`),
+        ).toEqual([
+          { directory: "/copy", strategy: "git_worktree" },
+          { directory: "/root", strategy: null },
+        ])
+      }),
+    )
+  })
+
   test("resets beta history and rebuilds event-sourced Session input storage", async () => {
     await run(
       Effect.gen(function* () {