feat: add flattenEntries/flattenGroups tree-flattening helpers

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WYqycDFsynHH9VnnK7LNSf

MyPassCore/Sources/MyPassCore/Session/GroupTree.swift

@@ -0,0 +1,46 @@
+import Foundation
+
+/// An entry paired with the full ancestor chain of groups leading to it, excluding the
+/// vault's root group. Empty `breadcrumb` means the entry lives directly in the root group.
+public struct FlatEntry: Identifiable, Equatable {
+    public let entry: Entry
+    public let parentGroupId: UUID
+    public let breadcrumb: [Group]
+    public var id: UUID { entry.id }
+}
+
+/// A group paired with the ancestor chain leading to its *parent*, excluding the vault's
+/// root group. The root group itself appears with an empty breadcrumb.
+public struct FlatGroup: Identifiable, Equatable {
+    public let group: Group
+    public let breadcrumb: [Group]
+    public var id: UUID { group.id }
+}
+
+/// Walks the vault tree once, pairing every entry with its full ancestor path.
+public func flattenEntries(in root: Group) -> [FlatEntry] {
+    var result: [FlatEntry] = []
+    func walk(_ group: Group, ancestorBreadcrumb: [Group]) {
+        for entry in group.entries {
+            result.append(FlatEntry(entry: entry, parentGroupId: group.id, breadcrumb: ancestorBreadcrumb))
+        }
+        for sub in group.subgroups {
+            walk(sub, ancestorBreadcrumb: ancestorBreadcrumb + [sub])
+        }
+    }
+    walk(root, ancestorBreadcrumb: [])
+    return result
+}
+
+/// Walks the vault tree once, producing every group (including the root) with its ancestor path.
+public func flattenGroups(in root: Group) -> [FlatGroup] {
+    var result: [FlatGroup] = [FlatGroup(group: root, breadcrumb: [])]
+    func walk(_ group: Group, ancestorBreadcrumb: [Group]) {
+        for sub in group.subgroups {
+            result.append(FlatGroup(group: sub, breadcrumb: ancestorBreadcrumb))
+            walk(sub, ancestorBreadcrumb: ancestorBreadcrumb + [sub])
+        }
+    }
+    walk(root, ancestorBreadcrumb: [])
+    return result
+}

MyPassCore/Tests/MyPassCoreTests/GroupTreeTests.swift

@@ -0,0 +1,52 @@
+import XCTest
+@testable import MyPassCore
+
+final class GroupTreeTests: XCTestCase {
+    private func makeSampleTree() -> (root: Group, work: Group, email: Group) {
+        let supportEntry = Entry(title: "Support Login", username: "alice")
+        let email = Group(name: "Email", entries: [supportEntry])
+        let bankEntry = Entry(title: "Bank", username: "bob")
+        let work = Group(name: "Work", subgroups: [email], entries: [bankEntry])
+        let rootEntry = Entry(title: "Root Entry", username: "root-user")
+        let root = Group(name: "Root", subgroups: [work], entries: [rootEntry])
+        return (root, work, email)
+    }
+
+    func test_flattenEntries_rootEntry_hasEmptyBreadcrumb() {
+        let (root, _, _) = makeSampleTree()
+        let flat = flattenEntries(in: root)
+        let rootEntry = flat.first { $0.entry.title == "Root Entry" }
+        XCTAssertEqual(rootEntry?.breadcrumb, [])
+        XCTAssertEqual(rootEntry?.parentGroupId, root.id)
+    }
+
+    func test_flattenEntries_directChildEntry_hasSingleGroupBreadcrumb() {
+        let (root, work, _) = makeSampleTree()
+        let flat = flattenEntries(in: root)
+        let bankEntry = flat.first { $0.entry.title == "Bank" }
+        XCTAssertEqual(bankEntry?.breadcrumb.map(\.name), ["Work"])
+        XCTAssertEqual(bankEntry?.parentGroupId, work.id)
+    }
+
+    func test_flattenEntries_nestedEntry_hasFullBreadcrumb() {
+        let (root, _, email) = makeSampleTree()
+        let flat = flattenEntries(in: root)
+        let supportEntry = flat.first { $0.entry.title == "Support Login" }
+        XCTAssertEqual(supportEntry?.breadcrumb.map(\.name), ["Work", "Email"])
+        XCTAssertEqual(supportEntry?.parentGroupId, email.id)
+    }
+
+    func test_flattenGroups_includesRootFirstWithEmptyBreadcrumb() {
+        let (root, _, _) = makeSampleTree()
+        let flat = flattenGroups(in: root)
+        XCTAssertEqual(flat.first?.group.id, root.id)
+        XCTAssertEqual(flat.first?.breadcrumb, [])
+    }
+
+    func test_flattenGroups_nestedGroup_hasBreadcrumb() {
+        let (root, _, _) = makeSampleTree()
+        let flat = flattenGroups(in: root)
+        let email = flat.first { $0.group.name == "Email" }
+        XCTAssertEqual(email?.breadcrumb.map(\.name), ["Work"])
+    }
+}