docs: add toolInfo.id alternative for localStorage persistence #427
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Add a simpler alternative to the viewUUID pattern for persisting view state. Uses hostContext.toolInfo.id (the JSON-RPC tool call ID) as the localStorage key, avoiding server-side UUID generation.
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| /** | ||
| * Example: Persisting view state using tool call ID (no server-side UUID needed) | ||
| */ | ||
| function persistViewStateWithToolCallId(app: App) { |
| // Use the tool call ID as a stable localStorage key — no server-side UUID needed | ||
| const toolCallId = String(app.getHostContext()?.toolInfo?.id ?? "default"); | ||
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| function saveState<T>(state: T): void { |
| try { localStorage.setItem(toolCallId, JSON.stringify(state)); } catch {} | ||
| } | ||
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| function loadState<T>(): T | null { |
@modelcontextprotocol/ext-apps
@modelcontextprotocol/server-basic-react
@modelcontextprotocol/server-basic-vanillajs
@modelcontextprotocol/server-budget-allocator
@modelcontextprotocol/server-cohort-heatmap
@modelcontextprotocol/server-customer-segmentation
@modelcontextprotocol/server-map
@modelcontextprotocol/server-pdf
@modelcontextprotocol/server-scenario-modeler
@modelcontextprotocol/server-shadertoy
@modelcontextprotocol/server-sheet-music
@modelcontextprotocol/server-system-monitor
@modelcontextprotocol/server-threejs
@modelcontextprotocol/server-transcript
@modelcontextprotocol/server-video-resource
@modelcontextprotocol/server-wiki-explorer
commit: |
Member
When would
Is there a risk that apps will break on some platforms if they rely on the presence of |
|
Imo using localstorage for state persistence is not a good recommendation. Ido opened #417 which I think will be the way to go. |
scutuatua-crypto
approved these changes
Feb 11, 2026
Contributor
|
Does the spec say anything about toolInfo.id's scope / uniqueness? |
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Adds a simpler alternative to the
viewUUIDpattern in the "Persisting view state" section.Instead of generating a UUID server-side and passing it via
_meta.viewUUID, developers can useapp.getHostContext()?.toolInfo.id— the JSON-RPC tool call ID — as the localStorage key directly.When to use this over viewUUID:
toolInfo.idis stable across page reloads (same tool call = same ID)Adds both the
patterns.mddocumentation and the type-checkedpatterns.tsxcode sample.