From cbdba20a238ad66cbca0cd47e81b3bfeb5699207 Mon Sep 17 00:00:00 2001
From: Chelsea Scott <chelseacat62@gmail.com>
Date: Thu, 18 Jun 2026 19:59:34 -0700
Subject: [PATCH 1/2] feat: add task status transition utility

---
 nexus-frontend/src/utils/transitions.ts | 40 +++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 nexus-frontend/src/utils/transitions.ts

diff --git a/nexus-frontend/src/utils/transitions.ts b/nexus-frontend/src/utils/transitions.ts
new file mode 100644
index 0000000..e93cac2
--- /dev/null
+++ b/nexus-frontend/src/utils/transitions.ts
@@ -0,0 +1,40 @@
+import type { TaskStatus } from '../types/task';
+
+/**
+ * Defines the valid status transitions for tasks.
+ * State machine: TODO → IN_PROGRESS → IN_REVIEW → DONE
+ */
+const TRANSITION_MAP: Record<TaskStatus, TaskStatus[]> = {
+  TODO: ['IN_PROGRESS'],
+  IN_PROGRESS: ['IN_REVIEW'],
+  IN_REVIEW: ['DONE'],
+  DONE: [],
+};
+
+/**
+ * Returns the list of valid next statuses for a given current status.
+ * Returns an empty array if no transitions are available (terminal state).
+ */
+export function getValidTransitions(currentStatus: TaskStatus): TaskStatus[] {
+  return TRANSITION_MAP[currentStatus] ?? [];
+}
+
+/**
+ * Checks whether transitioning from one status to another is valid.
+ */
+export function isValidTransition(
+  from: TaskStatus,
+  to: TaskStatus
+): boolean {
+  return TRANSITION_MAP[from]?.includes(to) ?? false;
+}
+
+/**
+ * Human-readable labels for task statuses.
+ */
+export const STATUS_LABELS: Record<TaskStatus, string> = {
+  TODO: 'To Do',
+  IN_PROGRESS: 'In Progress',
+  IN_REVIEW: 'In Review',
+  DONE: 'Done',
+};

From 9c25db26e587fbf9dd6b6bf078ec6eaf1ae407a0 Mon Sep 17 00:00:00 2001
From: Chelsea Scott <chelseacat62@gmail.com>
Date: Fri, 19 Jun 2026 23:15:26 -0700
Subject: [PATCH 2/2] refactor: make transition map readonly and return shallow
 copies

---
 nexus-frontend/src/utils/transitions.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/nexus-frontend/src/utils/transitions.ts b/nexus-frontend/src/utils/transitions.ts
index e93cac2..a3b0ac7 100644
--- a/nexus-frontend/src/utils/transitions.ts
+++ b/nexus-frontend/src/utils/transitions.ts
@@ -4,7 +4,7 @@ import type { TaskStatus } from '../types/task';
  * Defines the valid status transitions for tasks.
  * State machine: TODO → IN_PROGRESS → IN_REVIEW → DONE
  */
-const TRANSITION_MAP: Record<TaskStatus, TaskStatus[]> = {
+const TRANSITION_MAP: Readonly<Record<TaskStatus, readonly TaskStatus[]>> = {
   TODO: ['IN_PROGRESS'],
   IN_PROGRESS: ['IN_REVIEW'],
   IN_REVIEW: ['DONE'],
@@ -16,7 +16,7 @@ const TRANSITION_MAP: Record<TaskStatus, TaskStatus[]> = {
  * Returns an empty array if no transitions are available (terminal state).
  */
 export function getValidTransitions(currentStatus: TaskStatus): TaskStatus[] {
-  return TRANSITION_MAP[currentStatus] ?? [];
+  return [...(TRANSITION_MAP[currentStatus] ?? [])];
 }
 
 /**