diff --git a/src/context-map.ts b/src/context-map.ts
index 3721b4e..3dc107b 100644
--- a/src/context-map.ts
+++ b/src/context-map.ts
@@ -1,4 +1,11 @@
-import type { Context, Message, Tool } from "@earendil-works/pi-ai";
+import {
+  collapseSystemMessages,
+  getCurrentSystemPrompt,
+  getCurrentTools,
+  type Message,
+  type Tool,
+  type TranscriptContext,
+} from "@earendil-works/pi-ai";
 
 export interface ContentPart {
   type: "text" | "image";
@@ -39,13 +46,17 @@ function userContent(content: Message["content"]): string | ContentPart[] {
   return parts;
 }
 
-export function mapContextToChat(context: Context): MappedChat {
+export function mapContextToChat(context: TranscriptContext): MappedChat {
+  // Devin takes one leading system message and knows no mid-conversation system
+  // message, so replay the transcript deltas into the leading one first.
+  const transcript = collapseSystemMessages(context);
+  const systemPrompt = getCurrentSystemPrompt(transcript.messages);
   const messages: ChatHistoryItem[] = [];
-  if (context.systemPrompt) {
-    messages.push({ role: "system", content: context.systemPrompt });
+  if (systemPrompt) {
+    messages.push({ role: "system", content: systemPrompt });
   }
 
-  for (const message of context.messages) {
+  for (const message of transcript.messages) {
     if (message.role === "user") {
       messages.push({ role: "user", content: userContent(message.content) });
       continue;
@@ -86,7 +97,7 @@ export function mapContextToChat(context: Context): MappedChat {
     }
   }
 
-  const tools: ToolDef[] = (context.tools ?? []).map((tool: Tool) => ({
+  const tools: ToolDef[] = getCurrentTools(transcript.messages).map((tool: Tool) => ({
     name: tool.name,
     description: tool.description,
     parameters: tool.parameters,
diff --git a/src/stream.ts b/src/stream.ts
index 3cc3eb4..8404605 100644
--- a/src/stream.ts
+++ b/src/stream.ts
@@ -4,9 +4,9 @@ import {
   type Api,
   type AssistantMessage,
   type AssistantMessageEventStream,
-  type Context,
   type Model,
   type SimpleStreamOptions,
+  type TranscriptContext,
   calculateCost,
   createAssistantMessageEventStream,
 } from "@earendil-works/pi-ai";
@@ -402,7 +402,7 @@ async function* streamChatEvents(args: {
 
 export function streamDevin(
   model: Model<Api>,
-  context: Context,
+  context: TranscriptContext,
   options?: SimpleStreamOptions,
 ): AssistantMessageEventStream {
   const stream = createAssistantMessageEventStream();