Add dynamic() support to prompt.form() plugin API

- prompt.form() inputs can now have dynamic() callbacks that update
  reactively when form values change (same pattern as auth/template plugins)
- Changed PromptFormRequest routing from one-shot to bidirectional events
- Added PromptFormResponse.done field to distinguish intermediate updates
- Added optional size (enum) to PromptFormRequest for dialog sizing
- Added optional rows to FormInputEditor for fixed height editors
- New httpsnippet plugin: generates code snippets with dynamic language
  and library selectors that update the code preview in real-time

packages/plugin-runtime/src/PluginInstance.ts

@@ -1,7 +1,12 @@
 import console from 'node:console';
 import { type Stats, statSync, watch } from 'node:fs';
 import path from 'node:path';
-import type { Context, PluginDefinition } from '@yaakapp/api';
+import type {
+  CallPromptFormDynamicArgs,
+  Context,
+  DynamicPromptFormArg,
+  PluginDefinition,
+} from '@yaakapp/api';
 import {
   applyFormInputDefaults,
   validateTemplateFunctionArgs,
@@ -12,6 +17,7 @@ import type {
   DeleteModelResponse,
   FindHttpResponsesResponse,
   Folder,
+  FormInput,
   GetCookieValueRequest,
   GetCookieValueResponse,
   GetHttpRequestByIdResponse,
@@ -55,6 +61,7 @@ export class PluginInstance {
   #mod: PluginDefinition;
   #pluginToAppEvents: EventChannel;
   #appToPluginEvents: EventChannel;
+  #pendingDynamicForms = new Map<string, DynamicPromptFormArg[]>();
 
   constructor(workerData: PluginWorkerData, pluginEvents: EventChannel) {
     this.#workerData = workerData;
@@ -106,6 +113,7 @@ export class PluginInstance {
 
   async terminate() {
     await this.#mod?.dispose?.();
+    this.#pendingDynamicForms.clear();
     this.#unimportModule();
   }
 
@@ -664,10 +672,58 @@ export class PluginInstance {
           return reply.value;
         },
         form: async (args) => {
-          const reply: PromptFormResponse = await this.#sendForReply(context, {
-            type: 'prompt_form_request',
-            ...args,
+          // Strip dynamic callbacks before serializing (they can't cross the wire)
+          const strippedInputs = stripDynamicCallbacks(args.inputs);
+
+          // Build the event manually so we can get the event ID for keying
+          const eventToSend = this.#buildEventToSend(
+            context,
+            { type: 'prompt_form_request', ...args, inputs: strippedInputs },
+            null,
+          );
+
+          // Store original inputs (with dynamic callbacks) for later resolution
+          this.#pendingDynamicForms.set(eventToSend.id, args.inputs);
+
+          const reply = await new Promise<PromptFormResponse>((resolve) => {
+            const cb = (event: InternalEvent) => {
+              if (event.replyId !== eventToSend.id) return;
+
+              if (event.payload.type === 'prompt_form_response') {
+                const { done, values } = event.payload as PromptFormResponse;
+                if (done) {
+                  // Final response — resolve the promise and clean up
+                  this.#appToPluginEvents.unlisten(cb);
+                  this.#pendingDynamicForms.delete(eventToSend.id);
+                  resolve({ values } as PromptFormResponse);
+                } else {
+                  // Intermediate value change — resolve dynamic inputs and send back
+                  const storedInputs = this.#pendingDynamicForms.get(eventToSend.id);
+                  if (storedInputs && values) {
+                    const ctx = this.#newCtx(context);
+                    const callArgs: CallPromptFormDynamicArgs = { values };
+                    applyDynamicFormInput(ctx, storedInputs, callArgs)
+                      .then((resolvedInputs) => {
+                        const stripped = stripDynamicCallbacks(resolvedInputs);
+                        this.#sendPayload(
+                          context,
+                          { type: 'prompt_form_request', ...args, inputs: stripped },
+                          eventToSend.id,
+                        );
+                      })
+                      .catch((err) => {
+                        console.error('Failed to resolve dynamic form inputs', err);
+                      });
+                  }
+                }
+              }
+            };
+            this.#appToPluginEvents.listen(cb);
+
+            // Send the initial event after we start listening (to prevent race)
+            this.#sendEvent(eventToSend);
           });
+
           return reply.values;
         },
       },
@@ -906,6 +962,17 @@ export class PluginInstance {
   }
 }
 
+function stripDynamicCallbacks(inputs: DynamicPromptFormArg[]): FormInput[] {
+  return inputs.map((input) => {
+    // biome-ignore lint/suspicious/noExplicitAny: stripping dynamic from union type
+    const { dynamic, ...rest } = input as any;
+    if ('inputs' in rest && Array.isArray(rest.inputs)) {
+      rest.inputs = stripDynamicCallbacks(rest.inputs);
+    }
+    return rest as FormInput;
+  });
+}
+
 function genId(len = 5): string {
   const alphabet = '01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
   let id = '';

packages/plugin-runtime/src/common.ts

@@ -1,9 +1,21 @@
-import type { Context, DynamicAuthenticationArg, DynamicTemplateFunctionArg } from '@yaakapp/api';
+import type {
+  CallPromptFormDynamicArgs,
+  Context,
+  DynamicAuthenticationArg,
+  DynamicPromptFormArg,
+  DynamicTemplateFunctionArg,
+} from '@yaakapp/api';
 import type {
   CallHttpAuthenticationActionArgs,
   CallTemplateFunctionArgs,
 } from '@yaakapp-internal/plugins';
 
+type AnyDynamicArg = DynamicTemplateFunctionArg | DynamicAuthenticationArg | DynamicPromptFormArg;
+type AnyCallArgs =
+  | CallTemplateFunctionArgs
+  | CallHttpAuthenticationActionArgs
+  | CallPromptFormDynamicArgs;
+
 export async function applyDynamicFormInput(
   ctx: Context,
   args: DynamicTemplateFunctionArg[],
@@ -18,30 +30,40 @@ export async function applyDynamicFormInput(
 
 export async function applyDynamicFormInput(
   ctx: Context,
-  args: (DynamicTemplateFunctionArg | DynamicAuthenticationArg)[],
-  callArgs: CallTemplateFunctionArgs | CallHttpAuthenticationActionArgs,
-): Promise<(DynamicTemplateFunctionArg | DynamicAuthenticationArg)[]> {
-  const resolvedArgs: (DynamicTemplateFunctionArg | DynamicAuthenticationArg)[] = [];
+  args: DynamicPromptFormArg[],
+  callArgs: CallPromptFormDynamicArgs,
+): Promise<DynamicPromptFormArg[]>;
+
+export async function applyDynamicFormInput(
+  ctx: Context,
+  args: AnyDynamicArg[],
+  callArgs: AnyCallArgs,
+): Promise<AnyDynamicArg[]> {
+  const resolvedArgs: AnyDynamicArg[] = [];
   for (const { dynamic, ...arg } of args) {
     const dynamicResult =
       typeof dynamic === 'function'
         ? await dynamic(
             ctx,
-            callArgs as CallTemplateFunctionArgs & CallHttpAuthenticationActionArgs,
+            callArgs as CallTemplateFunctionArgs &
+              CallHttpAuthenticationActionArgs &
+              CallPromptFormDynamicArgs,
           )
         : undefined;
 
     const newArg = {
       ...arg,
       ...dynamicResult,
-    } as DynamicTemplateFunctionArg | DynamicAuthenticationArg;
+    } as AnyDynamicArg;
 
     if ('inputs' in newArg && Array.isArray(newArg.inputs)) {
       try {
         newArg.inputs = await applyDynamicFormInput(
           ctx,
           newArg.inputs as DynamicTemplateFunctionArg[],
-          callArgs as CallTemplateFunctionArgs & CallHttpAuthenticationActionArgs,
+          callArgs as CallTemplateFunctionArgs &
+            CallHttpAuthenticationActionArgs &
+            CallPromptFormDynamicArgs,
         );
       } catch (e) {
         console.error('Failed to apply dynamic form input', e);