feat: Thread optional `phase` param into `db/sessions.ts::cre… (+7 more)

- ✅ Thread optional `phase` param into `db/sessions.ts::createSession()`
- ✅ Thread optional `phase` param into `ipc/handlers.ts` sessions:create handler
- ✅ Thread optional `phase` param into `preload.ts` createSession API
- ✅ Update Plan phase system prompt to gracefully handle missing research.md
- ✅ Update Implement phase system prompt to gracefully handle missing plan.md
- ✅ Create `renderer/src/components/NewSessionModal.tsx`
- ✅ Update `App.tsx`: add modal state, split handler, add modal JSX
- ✅ Add modal CSS to `globals.css`

1 files changed, 4 insertions, 4 deletions

diff --git a/src/main/db/sessions.ts b/src/main/db/sessions.ts
index 3e6352c..bc22d15 100644
--- a/src/main/db/sessions.ts
+++ b/src/main/db/sessions.ts
@@ -36,21 +36,21 @@ export function getSession(id: string): Session | undefined {
     .get(id) as Session | undefined;
 }
 
-export function createSession(projectId: string, name: string): Session {
+export function createSession(projectId: string, name: string, phase: Phase = "research"): Session {
   const db = getDb();
   const id = uuid();
   const now = Math.floor(Date.now() / 1000);
 
   db.prepare(
     `INSERT INTO sessions (id, project_id, name, phase, permission_mode, created_at, updated_at)
-     VALUES (?, ?, ?, 'research', 'acceptEdits', ?, ?)`
-  ).run(id, projectId, name, now, now);
+     VALUES (?, ?, ?, ?, 'acceptEdits', ?, ?)`
+  ).run(id, projectId, name, phase, now, now);
 
   return {
     id,
     project_id: projectId,
     name,
-    phase: "research",
+    phase,
     claude_session_id: null,
     permission_mode: "acceptEdits",
     git_branch: null,