refactor(agent): export parseSSEStream

Author: marslavish

packages/agent/__tests__/run-handle.test.ts

@@ -9,10 +9,9 @@ import {
   createScriptedProvider,
   makeFakeAssistantMessage,
   makeFakeModel,
-  parseSSEStream,
 } from '@test/index';
 
-import { Agent, type AgentEvent, type AgentTool } from '../src';
+import { Agent, type AgentEvent, type AgentTool, parseSSEStream } from '../src';
 
 describe('AgentRunHandle', () => {
   describe('events()', () => {

packages/agent/__tests__/sse.test.ts

@@ -1,10 +1,7 @@
-// Exercises the `parseSSEStream` helper from tools/test/, not a production
-// parser. The kit ships no SSE parser today; consumers parse on their side.
-// These tests pin down the helper's edge-case behavior so future parser work
-// has a baseline to match.
-import { parseSSEStream } from '@test/index';
-
-import type { AgentEvent } from '../src';
+// Exercises `parseSSEStream` exported from `@agentic-kit/agent`. Symmetric to
+// the SSE producer in `toResponse()` — these tests pin down the parser's
+// edge-case behavior so the wire-format contract has a baseline.
+import { type AgentEvent, parseSSEStream } from '../src';
 
 const encoder = new TextEncoder();
 

packages/agent/src/index.ts

@@ -1,4 +1,5 @@
 export * from './agent.js';
 export * from './run-handle.js';
+export * from './sse.js';
 export * from './types.js';
 export * from './validation.js';

packages/agent/src/sse.ts

@@ -0,0 +1,67 @@
+import type { AgentEvent } from './types.js';
+
+export async function* parseSSEStream(
+  stream: ReadableStream<Uint8Array>
+): AsyncIterable<AgentEvent> {
+  const reader = stream.getReader();
+  const decoder = new TextDecoder('utf-8');
+  let buffer = '';
+
+  try {
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) {
+        break;
+      }
+
+      buffer += decoder.decode(value, { stream: true });
+      buffer = buffer.replace(/\r\n/g, '\n').replace(/\r/g, '\n');
+
+      let blankIdx = buffer.indexOf('\n\n');
+      while (blankIdx !== -1) {
+        const rawEvent = buffer.slice(0, blankIdx);
+        buffer = buffer.slice(blankIdx + 2);
+        const event = parseEvent(rawEvent);
+        if (event) {
+          yield event;
+        }
+        blankIdx = buffer.indexOf('\n\n');
+      }
+    }
+  } finally {
+    reader.releaseLock();
+  }
+}
+
+function parseEvent(raw: string): AgentEvent | null {
+  const dataLines: string[] = [];
+  for (const line of raw.split('\n')) {
+    if (line === '' || line.startsWith(':')) {
+      continue;
+    }
+    const colon = line.indexOf(':');
+    const field = colon === -1 ? line : line.slice(0, colon);
+    let value = colon === -1 ? '' : line.slice(colon + 1);
+    if (value.startsWith(' ')) {
+      value = value.slice(1);
+    }
+    if (field === 'data') {
+      dataLines.push(value);
+    }
+  }
+
+  if (dataLines.length === 0) {
+    return null;
+  }
+
+  const data = dataLines.join('\n');
+  if (data === '[DONE]') {
+    return null;
+  }
+
+  try {
+    return JSON.parse(data) as AgentEvent;
+  } catch {
+    return null;
+  }
+}

tools/test/index.ts

@@ -1,3 +1,3 @@
 export { makeFakeAssistantMessage, makeFakeModel } from './fixtures';
 export { createScriptedProvider, type ScriptedProviderOptions } from './scripted-provider';
-export { createScriptedSSEResponse, parseSSEStream } from './scripted-sse';
+export { createScriptedSSEResponse } from './scripted-sse';

tools/test/scripted-sse.ts

@@ -20,69 +20,3 @@ export function createScriptedSSEResponse(events: AgentEvent[]): Response {
     },
   });
 }
-
-export async function* parseSSEStream(
-  stream: ReadableStream<Uint8Array>
-): AsyncIterable<AgentEvent> {
-  const reader = stream.getReader();
-  const decoder = new TextDecoder('utf-8');
-  let buffer = '';
-
-  try {
-    while (true) {
-      const { done, value } = await reader.read();
-      if (done) {
-        break;
-      }
-
-      buffer += decoder.decode(value, { stream: true });
-      buffer = buffer.replace(/\r\n/g, '\n').replace(/\r/g, '\n');
-
-      let blankIdx = buffer.indexOf('\n\n');
-      while (blankIdx !== -1) {
-        const rawEvent = buffer.slice(0, blankIdx);
-        buffer = buffer.slice(blankIdx + 2);
-        const event = parseEvent(rawEvent);
-        if (event) {
-          yield event;
-        }
-        blankIdx = buffer.indexOf('\n\n');
-      }
-    }
-  } finally {
-    reader.releaseLock();
-  }
-}
-
-function parseEvent(raw: string): AgentEvent | null {
-  const dataLines: string[] = [];
-  for (const line of raw.split('\n')) {
-    if (line === '' || line.startsWith(':')) {
-      continue;
-    }
-    const colon = line.indexOf(':');
-    const field = colon === -1 ? line : line.slice(0, colon);
-    let value = colon === -1 ? '' : line.slice(colon + 1);
-    if (value.startsWith(' ')) {
-      value = value.slice(1);
-    }
-    if (field === 'data') {
-      dataLines.push(value);
-    }
-  }
-
-  if (dataLines.length === 0) {
-    return null;
-  }
-
-  const data = dataLines.join('\n');
-  if (data === '[DONE]') {
-    return null;
-  }
-
-  try {
-    return JSON.parse(data) as AgentEvent;
-  } catch {
-    return null;
-  }
-}