Add multi-diagram management

- DiagramRepository interface redesigned around multiple diagrams:
  list()/loadById()/deleteById() replace the old single-diagram
  load()/clear(). Both implementations updated to match.
- SupabaseDiagramRepository.save() now does an explicit update-or-insert
  instead of a blind upsert, so owner_id is only ever set at creation --
  an upsert would resend it on every save and let whoever saves last
  silently reassign ownership. Not reachable yet (no collaborator UI),
  but a real landmine once diagram sharing (organized-ideas.md §8) lands,
  and cheap to avoid now.
- LocalStorageDiagramRepository now stores diagrams keyed by id (was a
  single fixed key), keeping it a genuine working fallback rather than
  a stale reference implementing an old interface.
- Store: loadInitialDiagram (renamed from loadFromStorage) opens the
  last diagram you had open (tracked in localStorage -- a UI
  preference, not app data), falling back to the most recently updated
  one, falling back to a fresh empty diagram. New actions:
  refreshDiagramList, switchToDiagram, deleteDiagram. newProject and
  importProject now persist immediately (not just via the debounced
  autosave) so a new/imported diagram shows up in the list right away;
  importProject also assigns a fresh id so it can't collide with an
  existing diagram.
- New DiagramManagerModal (list/open/delete/+New), opened from a
  "Diagrams" button in TopBar that replaces the old single-diagram
  "New" button and its now-unnecessary confirmation dialog -- nothing
  is lost by creating a new diagram anymore, since the old one stays
  saved and reachable from the list.

Verified insert/list/update(-preserves-owner)/loadById/delete against
the real local stack; RLS test suite still 23/23 after a fresh reset.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017DUU6CnxECCDeqDNYJgr5x

src/components/layout/AppShell.tsx

@@ -8,11 +8,11 @@ import TopBar from './TopBar'
 
 export default function AppShell() {
   const isLoaded = useProjectStore((s) => s.isLoaded)
-  const loadFromStorage = useProjectStore((s) => s.loadFromStorage)
+  const loadInitialDiagram = useProjectStore((s) => s.loadInitialDiagram)
 
   useEffect(() => {
-    loadFromStorage()
-  }, [loadFromStorage])
+    loadInitialDiagram()
+  }, [loadInitialDiagram])
 
   if (!isLoaded) {
     return <div className="flex h-screen items-center justify-center text-sm text-slate-400">Loading…</div>

src/components/layout/DiagramManagerModal.tsx

@@ -0,0 +1,95 @@
+import { useEffect } from 'react'
+import { useProjectStore } from '../../state/projectStore'
+import Modal from '../common/Modal'
+
+function formatUpdatedAt(iso: string): string {
+  const date = new Date(iso)
+  return date.toLocaleString(undefined, { dateStyle: 'medium', timeStyle: 'short' })
+}
+
+export default function DiagramManagerModal({ onClose }: { onClose: () => void }) {
+  const project = useProjectStore((s) => s.project)
+  const diagramList = useProjectStore((s) => s.diagramList)
+  const refreshDiagramList = useProjectStore((s) => s.refreshDiagramList)
+  const newProject = useProjectStore((s) => s.newProject)
+  const switchToDiagram = useProjectStore((s) => s.switchToDiagram)
+  const deleteDiagram = useProjectStore((s) => s.deleteDiagram)
+
+  useEffect(() => {
+    refreshDiagramList()
+  }, [refreshDiagramList])
+
+  const handleOpen = async (id: string) => {
+    if (id === project.id) return
+    await switchToDiagram(id)
+    onClose()
+  }
+
+  const handleNew = async () => {
+    await newProject()
+    onClose()
+  }
+
+  const handleDelete = async (id: string, name: string) => {
+    const confirmed = window.confirm(
+      diagramList.length === 1
+        ? `Delete "${name}"? This is your only diagram, so a fresh empty one will replace it.`
+        : `Delete "${name}"? This can't be undone.`,
+    )
+    if (!confirmed) return
+    await deleteDiagram(id)
+  }
+
+  return (
+    <Modal title="Diagrams" onClose={onClose} width="max-w-lg">
+      <div className="space-y-3">
+        <button
+          onClick={handleNew}
+          className="w-full rounded bg-indigo-600 py-1.5 text-xs font-medium text-white hover:bg-indigo-500"
+        >
+          + New Diagram
+        </button>
+
+        <ul className="space-y-1">
+          {diagramList.map((d) => {
+            const isCurrent = d.id === project.id
+            return (
+              <li
+                key={d.id}
+                className={`group flex items-center justify-between gap-2 rounded border px-3 py-2 text-xs ${
+                  isCurrent ? 'border-indigo-300 bg-indigo-50' : 'border-slate-200 bg-white'
+                }`}
+              >
+                <button
+                  onClick={() => handleOpen(d.id)}
+                  disabled={isCurrent}
+                  className="min-w-0 flex-1 text-left disabled:cursor-default"
+                >
+                  <div className="flex items-center gap-1.5">
+                    <span className="truncate font-medium text-slate-700">{d.name}</span>
+                    {isCurrent && (
+                      <span className="shrink-0 rounded bg-indigo-100 px-1 text-[10px] font-medium text-indigo-700">
+                        current
+                      </span>
+                    )}
+                  </div>
+                  <div className="truncate text-[10px] text-slate-400">Updated {formatUpdatedAt(d.updatedAt)}</div>
+                </button>
+                <button
+                  onClick={() => handleDelete(d.id, d.name)}
+                  title="Delete this diagram"
+                  className="shrink-0 rounded px-1.5 py-0.5 text-slate-400 opacity-0 hover:bg-red-50 hover:text-red-600 group-hover:opacity-100"
+                >
+                  ✕
+                </button>
+              </li>
+            )
+          })}
+          {diagramList.length === 0 && (
+            <p className="py-2 text-center text-xs italic text-slate-400">No diagrams yet.</p>
+          )}
+        </ul>
+      </div>
+    </Modal>
+  )
+}

src/components/layout/TopBar.tsx

@@ -1,22 +1,15 @@
-import { useRef } from 'react'
+import { useRef, useState } from 'react'
 import { downloadProjectFile, readProjectFile, ProjectImportError } from '../../data/exportImport'
 import { supabase } from '../../data/supabaseClient'
 import { useProjectStore } from '../../state/projectStore'
+import DiagramManagerModal from './DiagramManagerModal'
 
 export default function TopBar() {
   const project = useProjectStore((s) => s.project)
   const renameProject = useProjectStore((s) => s.renameProject)
-  const newProject = useProjectStore((s) => s.newProject)
   const importProject = useProjectStore((s) => s.importProject)
   const fileInputRef = useRef<HTMLInputElement>(null)
-
-  const handleNewProject = () => {
-    if (project.devices.length > 0 || project.connections.length > 0) {
-      const confirmed = window.confirm('Start a new project? Unsaved changes to the current one will be lost (unless exported).')
-      if (!confirmed) return
-    }
-    newProject()
-  }
+  const [diagramManagerOpen, setDiagramManagerOpen] = useState(false)
 
   const handleExport = () => downloadProjectFile(project)
 
@@ -28,7 +21,7 @@ export default function TopBar() {
     if (!file) return
     try {
       const imported = await readProjectFile(file)
-      importProject(imported)
+      await importProject(imported)
     } catch (err) {
       const message = err instanceof ProjectImportError ? err.message : 'Could not read that file.'
       window.alert(`Import failed: ${message}`)
@@ -46,8 +39,11 @@ export default function TopBar() {
         />
       </div>
       <div className="flex items-center gap-1.5">
-        <button onClick={handleNewProject} className="rounded px-2.5 py-1.5 text-xs text-slate-600 hover:bg-slate-100">
-          New
+        <button
+          onClick={() => setDiagramManagerOpen(true)}
+          className="rounded px-2.5 py-1.5 text-xs text-slate-600 hover:bg-slate-100"
+        >
+          Diagrams
         </button>
         <button onClick={handleImportClick} className="rounded px-2.5 py-1.5 text-xs text-slate-600 hover:bg-slate-100">
           Import
@@ -66,6 +62,7 @@ export default function TopBar() {
           Sign out
         </button>
       </div>
+      {diagramManagerOpen && <DiagramManagerModal onClose={() => setDiagramManagerOpen(false)} />}
     </header>
   )
 }

src/data/DiagramRepository.ts

@@ -1,5 +1,13 @@
 import type { Project } from '../domain/types'
 
+/** Lightweight metadata for listing diagrams without fetching each one's
+ *  full (potentially large) data payload. */
+export interface DiagramSummary {
+  id: string
+  name: string
+  updatedAt: string
+}
+
 /**
  * Storage abstraction the rest of the app codes against. `LocalStorageDiagramRepository`
  * and `SupabaseDiagramRepository` both implement it — the store/UI layers don't need to
@@ -12,7 +20,12 @@ import type { Project } from '../domain/types'
  * across the whole app, tracked as its own task rather than bundled into this one.
  */
 export interface DiagramRepository {
-  load(): Promise<Project | null>
+  /** Every diagram visible to the current user, most recently updated first. */
+  list(): Promise<DiagramSummary[]>
+  /** One diagram's full data by id, or null if it doesn't exist / isn't visible. */
+  loadById(id: string): Promise<Project | null>
+  /** Upsert a diagram, matched by the project's own id. */
   save(project: Project): Promise<void>
-  clear(): Promise<void>
+  /** Permanently delete one diagram by id. */
+  deleteById(id: string): Promise<void>
 }

src/data/LocalStorageDiagramRepository.ts

@@ -1,28 +1,51 @@
 import type { Project } from '../domain/types'
-import type { DiagramRepository } from './DiagramRepository'
+import type { DiagramRepository, DiagramSummary } from './DiagramRepository'
 import { normalizeProject } from './exportImport'
 
-const STORAGE_KEY = 'av-planner:project:v1'
+const STORAGE_KEY = 'av-planner:diagrams:v1'
+
+type StoredDiagrams = Record<string, Project>
+
+function readAll(): StoredDiagrams {
+  try {
+    const raw = window.localStorage.getItem(STORAGE_KEY)
+    return raw ? (JSON.parse(raw) as StoredDiagrams) : {}
+  } catch (err) {
+    console.error('Failed to read diagrams from localStorage', err)
+    return {}
+  }
+}
+
+function writeAll(diagrams: StoredDiagrams): void {
+  window.localStorage.setItem(STORAGE_KEY, JSON.stringify(diagrams))
+}
 
 /** Kept around (no longer the active repository — see projectStore.ts) as a
- *  reference implementation and a safe fallback if Supabase is unreachable. */
+ *  reference implementation and a safe fallback if Supabase is unreachable.
+ *  Multiple diagrams are stored as one JSON object keyed by id, matching the
+ *  shape the Supabase-backed repository presents to the rest of the app. */
 export class LocalStorageDiagramRepository implements DiagramRepository {
-  async load(): Promise<Project | null> {
-    try {
-      const raw = window.localStorage.getItem(STORAGE_KEY)
-      if (!raw) return null
-      return normalizeProject(JSON.parse(raw) as Project)
-    } catch (err) {
-      console.error('Failed to load project from localStorage', err)
-      return null
-    }
+  async list(): Promise<DiagramSummary[]> {
+    const diagrams = Object.values(readAll())
+    return diagrams
+      .map((d) => ({ id: d.id, name: d.name, updatedAt: d.updatedAt }))
+      .sort((a, b) => b.updatedAt.localeCompare(a.updatedAt))
+  }
+
+  async loadById(id: string): Promise<Project | null> {
+    const diagram = readAll()[id]
+    return diagram ? normalizeProject(diagram) : null
   }
 
   async save(project: Project): Promise<void> {
-    window.localStorage.setItem(STORAGE_KEY, JSON.stringify(project))
+    const all = readAll()
+    all[project.id] = project
+    writeAll(all)
   }
 
-  async clear(): Promise<void> {
-    window.localStorage.removeItem(STORAGE_KEY)
+  async deleteById(id: string): Promise<void> {
+    const all = readAll()
+    delete all[id]
+    writeAll(all)
   }
 }

src/data/SupabaseDiagramRepository.ts

@@ -1,5 +1,5 @@
 import type { Project } from '../domain/types'
-import type { DiagramRepository } from './DiagramRepository'
+import type { DiagramRepository, DiagramSummary } from './DiagramRepository'
 import { normalizeProject } from './exportImport'
 import { supabase } from './supabaseClient'
 
@@ -10,24 +10,25 @@ import { supabase } from './supabaseClient'
  * migration's header comment for why diagrams are a document, not
  * normalized relational rows.
  *
- * Single-diagram scope for now, matching the app's current UI (one active
- * project at a time): `load()` returns the signed-in user's most recently
- * updated diagram, `save()` upserts by the diagram's own id. Multi-diagram
- * management (list/switch between several) is a later phase.
+ * RLS already scopes every query here to what the signed-in user can see
+ * (their own diagrams, plus anything shared with them per organized-ideas.md
+ * §8) — no need to filter by owner_id client-side.
  */
 export class SupabaseDiagramRepository implements DiagramRepository {
-  async load(): Promise<Project | null> {
-    const {
-      data: { user },
-    } = await supabase.auth.getUser()
-    if (!user) return null
+  async list(): Promise<DiagramSummary[]> {
+    const { data, error } = await supabase.from('diagrams').select('id, name, updated_at').order('updated_at', {
+      ascending: false,
+    })
 
-    const { data: row, error } = await supabase
-      .from('diagrams')
-      .select('data')
-      .order('updated_at', { ascending: false })
-      .limit(1)
-      .maybeSingle()
+    if (error) {
+      console.error('Failed to list diagrams from Supabase', error)
+      return []
+    }
+    return (data ?? []).map((row) => ({ id: row.id, name: row.name, updatedAt: row.updated_at }))
+  }
+
+  async loadById(id: string): Promise<Project | null> {
+    const { data: row, error } = await supabase.from('diagrams').select('data').eq('id', id).maybeSingle()
 
     if (error) {
       console.error('Failed to load diagram from Supabase', error)
@@ -46,28 +47,27 @@ export class SupabaseDiagramRepository implements DiagramRepository {
       return
     }
 
-    const { error } = await supabase.from('diagrams').upsert({
-      id: project.id,
-      name: project.name,
-      owner_id: user.id,
-      data: project,
-      updated_at: new Date().toISOString(),
-    })
+    // Deliberately update-or-insert rather than a blind upsert: an upsert
+    // would resend owner_id on every save and silently reassign ownership
+    // to whoever saves last. Not reachable yet (no collaborator UI exists),
+    // but once diagram sharing (§8) lands, an edit-collaborator saving
+    // changes must never be able to overwrite who owns the diagram.
+    const { data: existing } = await supabase.from('diagrams').select('id').eq('id', project.id).maybeSingle()
+    const payload = { name: project.name, data: project, updated_at: new Date().toISOString() }
+
+    const { error } = existing
+      ? await supabase.from('diagrams').update(payload).eq('id', project.id)
+      : await supabase.from('diagrams').insert({ id: project.id, owner_id: user.id, ...payload })
 
     if (error) {
       console.error('Failed to save diagram to Supabase', error)
     }
   }
 
-  async clear(): Promise<void> {
-    const {
-      data: { user },
-    } = await supabase.auth.getUser()
-    if (!user) return
-
-    const { error } = await supabase.from('diagrams').delete().eq('owner_id', user.id)
+  async deleteById(id: string): Promise<void> {
+    const { error } = await supabase.from('diagrams').delete().eq('id', id)
     if (error) {
-      console.error('Failed to clear diagrams from Supabase', error)
+      console.error('Failed to delete diagram from Supabase', error)
     }
   }
 }

src/state/projectStore.ts

@@ -3,7 +3,7 @@ import { create } from 'zustand'
 import { validateConnection } from '../domain/compatibility'
 import { allDeviceTemplates, createDeviceFromTemplate, createEmptyProject, incrementPortName } from '../domain/project'
 import type { CableType, Connection, Device, DeviceCategory, DeviceTemplate, Port, PortType, Project } from '../domain/types'
-import type { DiagramRepository } from '../data/DiagramRepository'
+import type { DiagramRepository, DiagramSummary } from '../data/DiagramRepository'
 import { SupabaseDiagramRepository } from '../data/SupabaseDiagramRepository'
 
 // This is exactly the swap the repository pattern was built for: only this
@@ -13,18 +13,63 @@ import { SupabaseDiagramRepository } from '../data/SupabaseDiagramRepository'
 // codebase as a reference implementation / fallback, just no longer active.
 const repository: DiagramRepository = new SupabaseDiagramRepository()
 
+// Which diagram to reopen on next launch — a session/UI preference, not app
+// data, so it lives in localStorage even though the diagrams themselves are
+// in Supabase now. Falls back gracefully (see loadInitialDiagram) if the
+// referenced diagram no longer exists.
+const LAST_DIAGRAM_ID_KEY = 'av-planner:lastDiagramId'
+function getLastDiagramId(): string | null {
+  try {
+    return window.localStorage.getItem(LAST_DIAGRAM_ID_KEY)
+  } catch {
+    return null
+  }
+}
+function setLastDiagramId(id: string): void {
+  try {
+    window.localStorage.setItem(LAST_DIAGRAM_ID_KEY, id)
+  } catch {
+    // Not essential — worst case, next launch falls back to the most
+    // recently updated diagram instead of this exact one.
+  }
+}
+
+async function loadMostRecent(): Promise<Project | null> {
+  const list = await repository.list()
+  if (list.length === 0) return null
+  return repository.loadById(list[0].id)
+}
+
 interface ProjectStoreState {
   project: Project
   isLoaded: boolean
+  /** Every diagram the current user can see, most recently updated first.
+   *  Populated by refreshDiagramList — not kept live-synced on every store
+   *  change, just refreshed at the moments that matter (initial load, and
+   *  whenever the diagram manager UI opens or changes something). */
+  diagramList: DiagramSummary[]
   selectedDeviceId: string | null
   selectedConnectionId: string | null
   lastConnectionError: string | null
   clearConnectionError: () => void
 
-  loadFromStorage: () => Promise<void>
-  newProject: (name?: string) => void
+  /** Figures out which diagram to open on launch (last one you had open, else
+   *  most recently updated, else a fresh empty one) and loads it. */
+  loadInitialDiagram: () => Promise<void>
+  refreshDiagramList: () => Promise<void>
+  /** Creates a new diagram, makes it current, and persists it immediately
+   *  (not just via the debounced autosave) so it shows up in the list right away. */
+  newProject: (name?: string) => Promise<void>
   renameProject: (name: string) => void
-  importProject: (project: Project) => void
+  /** Imports diagram data under a fresh id, so it's added as a new diagram
+   *  rather than risking a collision with (or silently overwriting) an
+   *  existing one that happens to share the file's id. */
+  importProject: (project: Project) => Promise<void>
+  /** Switches the active diagram to another one of the user's own. */
+  switchToDiagram: (id: string) => Promise<void>
+  /** Permanently deletes a diagram. If it's the currently open one, falls
+   *  back to another existing diagram, or a fresh empty one if none remain. */
+  deleteDiagram: (id: string) => Promise<void>
 
   selectDevice: (id: string | null) => void
   selectConnection: (id: string | null) => void
@@ -79,26 +124,62 @@ function touch(project: Project): Project {
 export const useProjectStore = create<ProjectStoreState>((set, get) => ({
   project: createEmptyProject(),
   isLoaded: false,
+  diagramList: [],
   selectedDeviceId: null,
   selectedConnectionId: null,
   lastConnectionError: null,
   clearConnectionError: () => set({ lastConnectionError: null }),
 
-  loadFromStorage: async () => {
-    const loaded = await repository.load()
-    set({ project: loaded ?? createEmptyProject(), isLoaded: true })
+  loadInitialDiagram: async () => {
+    const lastId = getLastDiagramId()
+    const loaded = lastId ? await repository.loadById(lastId) : null
+    const project = loaded ?? (await loadMostRecent()) ?? createEmptyProject()
+    setLastDiagramId(project.id)
+    set({ project, isLoaded: true })
+    get().refreshDiagramList()
   },
 
-  newProject: (name = 'Untitled Project') => {
-    set({ project: createEmptyProject(name), selectedDeviceId: null, selectedConnectionId: null })
+  refreshDiagramList: async () => {
+    const diagramList = await repository.list()
+    set({ diagramList })
+  },
+
+  newProject: async (name = 'Untitled Project') => {
+    const project = createEmptyProject(name)
+    setLastDiagramId(project.id)
+    set({ project, selectedDeviceId: null, selectedConnectionId: null })
+    await repository.save(project)
+    get().refreshDiagramList()
   },
 
   renameProject: (name) => {
     set((state) => ({ project: touch({ ...state.project, name }) }))
   },
 
-  importProject: (project) => {
-    set({ project: touch(project), selectedDeviceId: null, selectedConnectionId: null })
+  importProject: async (project) => {
+    const fresh = touch({ ...project, id: uuid() })
+    setLastDiagramId(fresh.id)
+    set({ project: fresh, selectedDeviceId: null, selectedConnectionId: null })
+    await repository.save(fresh)
+    get().refreshDiagramList()
+  },
+
+  switchToDiagram: async (id) => {
+    if (id === get().project.id) return
+    const loaded = await repository.loadById(id)
+    if (!loaded) return
+    setLastDiagramId(loaded.id)
+    set({ project: loaded, selectedDeviceId: null, selectedConnectionId: null })
+  },
+
+  deleteDiagram: async (id) => {
+    await repository.deleteById(id)
+    if (get().project.id === id) {
+      const next = (await loadMostRecent()) ?? createEmptyProject()
+      setLastDiagramId(next.id)
+      set({ project: next, selectedDeviceId: null, selectedConnectionId: null })
+    }
+    get().refreshDiagramList()
   },
 
   selectDevice: (id) => set({ selectedDeviceId: id, selectedConnectionId: null }),