fix: take latest re-reads the head at click time; type the kept head as prepared diff data

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/lib/components/DiffDrawer.svelte

@@ -94,10 +94,11 @@
 	let selectedVersion: string | undefined = $state(undefined)
 	let versionLoader: ((id: string) => Promise<Value | undefined>) | undefined = $state(undefined)
 	let headLabel: string | undefined = $state(undefined)
-	/** The deployed head as it was handed to `setDiff`. `data.deployed` follows the
-	 *  picker, and Restore always restores the head, so its enabled state compares
-	 *  against this rather than whichever version is on display. */
-	let headDeployed: Value | undefined = $state(undefined)
+	/** The deployed head, prepared for diffing as `data.deployed` is: `data.deployed`
+	 *  follows the picker while Restore always restores the head, so its enabled state
+	 *  compares against this. Must hold `prepareDiff`'s output, not the raw value, or the
+	 *  comparison never matches and Restore is always enabled. */
+	let headDeployed: ReturnType<typeof prepareDiff> | undefined = $state(undefined)
 	let loadingVersion = $state(false)
 	/** Which version load the spinner belongs to, counted rather than keyed on the id so
 	 *  re-picking the same version is still generation-safe. A response from any other

frontend/src/routes/(root)/(logged)/apps_raw/edit/[...path]/+page.svelte

@@ -629,7 +629,15 @@
 				deployedHeadVersion &&
 				draftBaseVersion !== deployedHeadVersion
 					? async () => {
-							const head = Number(deployedHeadVersion)
+							// Re-read rather than trusting the head this page loaded with; see
+							// /scripts/edit.
+							const head =
+								(
+									await AppService.getAppLatestVersion({
+										workspace: $workspaceStore!,
+										path: page.params.path ?? ''
+									}).catch(() => undefined)
+								)?.version ?? Number(deployedHeadVersion)
 							parentVersion = head
 							if (deployedBaseline) deployedBaseline = { ...deployedBaseline, parent_version: head }
 							draftBaseVersion = String(head)

frontend/src/routes/(root)/(logged)/flows/edit/[...path]/+page.svelte

@@ -546,7 +546,15 @@
 	<FlowBuilder
 		onTakeLatest={draftBaseVersion && version != null && draftBaseVersion !== String(version)
 			? async () => {
-					const head = version
+					// Re-read rather than trusting the head this page loaded with; see
+					// /scripts/edit.
+					const head =
+						(
+							await FlowService.getFlowLatestVersion({
+								workspace: $workspaceStore!,
+								path: flowDraftPath
+							}).catch(() => undefined)
+						)?.id ?? version
 					if (!draftSync.draft || head == null || !$workspaceStore) return
 					draftSync.draft = { ...draftSync.draft, version_id: head }
 					draftBaseVersion = String(head)

frontend/src/routes/(root)/(logged)/scripts/edit/[...path]/+page.svelte

@@ -527,7 +527,16 @@
 		userDraftPath={draftPath}
 		onTakeLatest={draftBaseHash && deployedHeadHash && draftBaseHash !== deployedHeadHash
 			? async () => {
-					const head = deployedHeadHash
+					// Re-read rather than trusting the head this page loaded with: taking a
+					// stale one would say the draft is up to date with a version that is not
+					// the latest any more.
+					const head =
+						(
+							await ScriptService.getScriptLatestVersion({
+								workspace: $workspaceStore!,
+								path: draftPath
+							}).catch(() => undefined)
+						)?.script_hash ?? deployedHeadHash
 					if (!draftSync.draft || !head || !$workspaceStore) return
 					draftSync.draft = { ...draftSync.draft, parent_hash: head }
 					// The baseline mirrors the draft's base so an unedited draft still