feat(pipeline): optional AI prompt when creating a pipeline script

frontend/src/lib/components/assets/AssetGraph/AddNode.svelte

@@ -31,7 +31,8 @@
 				source:
 					| { kind: 'schedule'; cron: string }
 					| { kind: NativeTriggerKind; path: string | undefined },
-				outputKind: PipelineOutputKind
+				outputKind: PipelineOutputKind,
+				aiPrompt?: string
 			) => void
 			pathPrefix: string
 			defaultPathSuffix: string
@@ -49,7 +50,8 @@
 				pick.language as ScriptLang,
 				pick.path,
 				{ kind: 'schedule', cron: data.defaultScheduleCron },
-				outputKind
+				outputKind,
+				pick.aiPrompt
 			)
 		} else {
 			// Native trigger reference: user is expected to fill in the
@@ -60,7 +62,8 @@
 				pick.language as ScriptLang,
 				pick.path,
 				{ kind: kindId, path: undefined },
-				outputKind
+				outputKind,
+				pick.aiPrompt
 			)
 		}
 	}

frontend/src/lib/components/assets/AssetGraph/AssetGraphCanvas.svelte

@@ -36,11 +36,15 @@
 			asset: { kind: AssetKind; path: string },
 			language: import('$lib/gen').ScriptLang,
 			scriptPath: string,
-			outputKind: import('./pipelineTemplates').PipelineOutputKind
+			outputKind: import('./pipelineTemplates').PipelineOutputKind,
+			aiPrompt?: string
 		) => void
 		// Pipeline-wide + node shown at the top of the graph. Picking any
 		// kind from the menu invokes this one callback with the chosen
 		// trigger source — the page uses it to seed the draft's annotation.
+		// `aiPrompt` is set when the user filled the optional prompt field
+		// on the path stage; the page is expected to bootstrap the body via
+		// AI instead of using the seeded template.
 		onAddPipelineScript?: (
 			language: import('$lib/gen').ScriptLang,
 			path: string,
@@ -50,7 +54,8 @@
 						kind: 'webhook' | 'email' | 'kafka' | 'mqtt' | 'nats' | 'postgres' | 'sqs' | 'gcp'
 						path: string | undefined
 				  },
-			outputKind: import('./pipelineTemplates').PipelineOutputKind
+			outputKind: import('./pipelineTemplates').PipelineOutputKind,
+			aiPrompt?: string
 		) => void
 		// Folder-scoped prefix shown as a read-only chip in the insert menu
 		// path input (e.g. `f/{folder}/`). Shared across top + and per-asset +.

frontend/src/lib/components/assets/AssetGraph/AssetNode.svelte

@@ -30,7 +30,8 @@
 				asset: { kind: AssetKind; path: string },
 				language: ScriptLang,
 				scriptPath: string,
-				outputKind: PipelineOutputKind
+				outputKind: PipelineOutputKind,
+				aiPrompt?: string
 			) => void
 			pathPrefix?: string
 			defaultPathSuffix?: string
@@ -102,7 +103,8 @@
 				{ kind: data.asset_kind, path: data.path },
 				pick.language as ScriptLang,
 				pick.path,
-				(pick.outputKind ?? 'none') as PipelineOutputKind
+				(pick.outputKind ?? 'none') as PipelineOutputKind,
+				pick.aiPrompt
 			)
 		}
 	}

frontend/src/lib/components/assets/AssetGraph/PipelineInsertMenu.svelte

@@ -21,6 +21,11 @@
 		// Picked output asset kind. Optional because some menu instances
 		// (those without `pickOutputKind`) skip that stage entirely.
 		outputKind?: string
+		// Optional natural-language prompt entered on the path stage.
+		// When set, the caller is expected to bootstrap the script body
+		// from this prompt via AI (using language + outputKind + the
+		// upstream input as context) instead of using the seeded template.
+		aiPrompt?: string
 	}
 </script>
 
@@ -28,7 +33,7 @@
 	import Popover from '$lib/components/meltComponents/Popover.svelte'
 	import Button from '$lib/components/common/button/Button.svelte'
 	import LanguageIcon from '$lib/components/common/languageIcons/LanguageIcon.svelte'
-	import { ArrowLeft, ChevronRight } from 'lucide-svelte'
+	import { ArrowLeft, ChevronRight, Sparkles } from 'lucide-svelte'
 	import { tick } from 'svelte'
 	import {
 		PIPELINE_OUTPUT_KINDS,
@@ -91,6 +96,11 @@
 	let selectedOutputKind = $state<PipelineOutputKind | undefined>(undefined)
 	let pathSuffix = $state('')
 	let pathInput: HTMLInputElement | undefined = $state(undefined)
+	// Optional AI prompt — when filled the caller bootstraps the script
+	// body via AI instead of the seeded template (see the PipelineInsertPick
+	// docstring above). Cleared on menu close along with the rest of the
+	// stage state so a stale prompt from a previous open doesn't leak.
+	let aiPrompt = $state('')
 
 	// Keyboard navigation state. `focusCol` tracks which column the arrow
 	// keys steer; per-column indexes survive column switches so the user's
@@ -128,6 +138,7 @@
 		selectedLanguage = languages[defaultLangIdx()]?.lang
 		selectedOutputKind = undefined
 		pathSuffix = ''
+		aiPrompt = ''
 		focusCol = 'lang'
 		kindIdx = 0
 		langIdx = defaultLangIdx()
@@ -302,11 +313,13 @@
 		const suffix = pathSuffix.trim()
 		if (!suffix || !selectedLanguage) return
 		if (pickOutputKind && !selectedOutputKind) return
+		const trimmedPrompt = aiPrompt.trim()
 		onPick({
 			kindId: selectedKindId,
 			language: selectedLanguage,
 			path: pathPrefix + suffix,
-			outputKind: pickOutputKind ? selectedOutputKind : undefined
+			outputKind: pickOutputKind ? selectedOutputKind : undefined,
+			aiPrompt: trimmedPrompt.length > 0 ? trimmedPrompt : undefined
 		})
 		close()
 	}
@@ -522,14 +535,38 @@
 							</div>
 							<span class="text-2xs text-tertiary">Press Enter to create</span>
 						</div>
+						<div class="flex flex-col gap-1">
+							<span class="flex items-center gap-1 text-2xs font-normal text-secondary">
+								<Sparkles size={11} />
+								AI prompt (optional)
+							</span>
+							<textarea
+								bind:value={aiPrompt}
+								onkeydown={(e) => {
+									// Cmd/Ctrl-Enter to submit even when focus is in
+									// the textarea — bare Enter inserts a newline
+									// (multi-line prompts are common).
+									if ((e.metaKey || e.ctrlKey) && e.key === 'Enter') {
+										e.preventDefault()
+										confirmPath(close)
+									}
+								}}
+								class="border rounded-md bg-surface px-2 py-1.5 text-2xs font-normal min-h-[60px] resize-y focus:outline-none focus-visible:ring-2 focus-visible:ring-emerald-400"
+								placeholder="Describe what the script should do — leave empty to use the seeded template"
+							></textarea>
+							<span class="text-2xs text-tertiary">
+								Filled in: AI generates the body using language + selected output as context.
+							</span>
+						</div>
 						<div class="flex justify-end mt-auto">
 							<Button
 								variant="accent"
 								unifiedSize="sm"
 								disabled={!pathSuffix.trim()}
 								onClick={() => confirmPath(close)}
+								startIcon={aiPrompt.trim() ? { icon: Sparkles } : undefined}
 							>
-								Create
+								{aiPrompt.trim() ? 'Generate' : 'Create'}
 							</Button>
 						</div>
 					</div>

frontend/src/routes/(root)/(logged)/pipeline/[folder]/+page.svelte

@@ -23,7 +23,8 @@
 		type DraftTriggerSource
 	} from '$lib/components/assets/AssetGraph/pipelineTemplates'
 	import { decodeState, encodeState } from '$lib/utils'
-	import { onMount, untrack } from 'svelte'
+	import { onMount, tick, untrack } from 'svelte'
+	import { aiChatManager } from '$lib/components/copilot/chat/AIChatManager.svelte'
 	import {
 		AlertTriangle,
 		ArrowLeft,
@@ -314,7 +315,8 @@
 		scriptPath: string,
 		triggers: DraftTriggerSource[],
 		outputKind: PipelineOutputKind,
-		input?: { kind: AssetKind; path: string }
+		input?: { kind: AssetKind; path: string },
+		aiPrompt?: string
 	) {
 		const out = autoOutputAsset(outputKind, folder, language)
 		const script = buildDraft(language, scriptPath, triggers, outputKind, out, input)
@@ -327,6 +329,43 @@
 		drafts = next
 		activeDraftPath = scriptPath
 		selection = undefined
+
+		// User filled the optional prompt on the path stage — fire off a
+		// chat request so the AI bootstraps the body. The seeded template
+		// (already in `script.content`) acts as scaffolding the AI
+		// rewrites; language + chosen output + upstream input go in as
+		// context so the model knows what to read from / write to.
+		if (aiPrompt && aiPrompt.trim().length > 0) {
+			void triggerAiBootstrap({ scriptPath, language, outputKind, input, out, prompt: aiPrompt })
+		}
+	}
+
+	async function triggerAiBootstrap(args: {
+		scriptPath: string
+		language: ScriptLang
+		outputKind: PipelineOutputKind
+		input?: { kind: AssetKind; path: string }
+		out?: { kind: AssetKind; path: string }
+		prompt: string
+	}) {
+		// Wait one tick for AssetGraphDetailsPane to mount the ScriptEditor
+		// and register itself with aiChatManager (scriptEditorApplyCode etc.).
+		// Without this, openChat fires before the chat has a target editor.
+		await tick()
+		const lines: string[] = [args.prompt]
+		lines.push('')
+		lines.push(`Language: ${args.language}.`)
+		if (args.input) {
+			lines.push(`Read input from ${args.input.kind} \`${args.input.path}\`.`)
+		}
+		if (args.out) {
+			lines.push(`Write output to ${args.out.kind} \`${args.out.path}\`.`)
+		} else if (args.outputKind === 'none') {
+			lines.push('No output asset is expected.')
+		}
+		const instructions = lines.join('\n')
+		aiChatManager.openChat()
+		aiChatManager.sendRequest({ instructions })
 	}
 
 	// Navigation guard state. `pendingNavigationUrl` holds the URL the user
@@ -1152,7 +1191,7 @@
 										selection = s
 									}
 								}}
-								onAddScriptForAsset={(asset, language, scriptPath, outputKind) => {
+								onAddScriptForAsset={(asset, language, scriptPath, outputKind, aiPrompt) => {
 									const ref = `${ASSET_PREFIX[asset.kind]}${asset.path}`
 									openMaterializerDraft(
 										language,
@@ -1162,11 +1201,19 @@
 										{
 											kind: asset.kind,
 											path: asset.path
-										}
+										},
+										aiPrompt
 									)
 								}}
-								onAddPipelineScript={(language, scriptPath, source, outputKind) =>
-									openMaterializerDraft(language, scriptPath, [source], outputKind)}
+								onAddPipelineScript={(language, scriptPath, source, outputKind, aiPrompt) =>
+									openMaterializerDraft(
+										language,
+										scriptPath,
+										[source],
+										outputKind,
+										undefined,
+										aiPrompt
+									)}
 								onRunnableMenuRemove={(info) => {
 									// Drafts: drop the local entry immediately — the
 									// existing onDiscard pathway already handles this