chore: import upstream snapshot with attribution

apps/sim/lib/workflows/tool-input/synthetic-subblocks.ts

@@ -0,0 +1,60 @@
+const TOOL_SUBBLOCK_INFIX = '-tool-'
+const SYNTHETIC_TOOL_SUBBLOCK_RE = new RegExp(`${TOOL_SUBBLOCK_INFIX}\\d+-`)
+
+/**
+ * Builds the synthetic subblock id used to render a block-based tool's param
+ * inside a tool row.
+ *
+ * The id follows `{subBlockId}-tool-{index}-{paramId}` and is an ephemeral,
+ * client-only projection key for the value held canonically at
+ * `tool.params[paramId]` in the aggregate `tool-input` subblock.
+ */
+export function buildToolSubBlockId(
+  aggregateSubBlockId: string,
+  toolIndex: number,
+  paramId: string
+): string {
+  return `${aggregateSubBlockId}${TOOL_SUBBLOCK_INFIX}${toolIndex}-${paramId}`
+}
+
+/**
+ * Returns true for ToolSubBlockRenderer mirror subblocks produced by
+ * {@link buildToolSubBlockId}. These duplicate values already stored in the
+ * aggregate `tool-input` subblock and must never be persisted or compared.
+ */
+export function isSyntheticToolSubBlockId(subBlockId: string): boolean {
+  return SYNTHETIC_TOOL_SUBBLOCK_RE.test(subBlockId)
+}
+
+type ToolParamSyncAction =
+  | { action: 'noop' }
+  | { action: 'reproject' }
+  | { action: 'mirror'; value: string }
+
+/**
+ * Reconciles a change to a synthetic tool subblock value with the canonical
+ * `tool.params`. The synthetic key is a projection of `tool.params`, so:
+ *
+ * - `undefined` means the key was dropped by a wholesale store replace — restore
+ *   it from `tool.params` ({@link ToolParamSyncAction.action} `reproject`). A
+ *   removal is never a user clear.
+ * - any defined value (including `''` or `null`, both meaning "cleared by the
+ *   user") is a genuine edit to write back (`mirror`).
+ * - a value already matching `syncedValue` needs no work (`noop`).
+ */
+export function resolveToolParamSync(
+  storeValue: unknown,
+  syncedValue: string | null
+): ToolParamSyncAction {
+  if (storeValue === undefined) return { action: 'reproject' }
+
+  const stringified =
+    storeValue === null
+      ? ''
+      : typeof storeValue === 'string'
+        ? storeValue
+        : JSON.stringify(storeValue)
+
+  if (stringified === syncedValue) return { action: 'noop' }
+  return { action: 'mirror', value: stringified }
+}