fix: remove avoidable model runtime limits

Preserve long histories and parsed attachments, expose paged process and Subagent output, isolate MCP discovery failures, and expand browser snapshots and knowledge result selection. Remove fixed Harness output and updated remote Runtime duration limits.

Keep released Agent profile and v1 bridge compatibility while enabling larger framed exchanges and optional limits for updated peers. Document remote coverage requirements and real-model boundary validation.

Release note: Long model tasks can retain more context and continue reading complete tool output; remote execution preserves compatibility with released Agents. Updated remote limits require an updated Agent and Runtime bundle.

src/main/remote-agent/main-model-bridge-session.test.ts

@@ -172,12 +172,13 @@ async function sentMessage(
   channel: FakeBlobChannel,
   offset = 0
 ) {
-  await vi.waitFor(() =>
+  await vi.waitFor(() => {
     expect(channel.sent.length).toBeGreaterThan(offset)
-  )
+    expect(() => JSON.parse(Buffer.concat(channel.sent.slice(offset)).toString())).not.toThrow()
+  })
   return {
-    message: await decodeModelBridgeMessage(channel.sent[offset]!),
-    nextOffset: offset + 1
+    message: await decodeModelBridgeMessage(Buffer.concat(channel.sent.slice(offset))),
+    nextOffset: channel.sent.length
   }
 }
 
@@ -315,7 +316,7 @@ describe('MainModelBridgeSession', () => {
     })
   })
 
-  it('delivers a maximum-sized response in one bounded message', async () => {
+  it('delivers a maximum-sized response across bounded transport frames', async () => {
     const channel = new FakeBlobChannel()
     const largeResponse = {
       ...response,
@@ -331,11 +332,11 @@ describe('MainModelBridgeSession', () => {
     })
     const requestMessage = await pushRequest(channel, 0)
     const outgoing = await sentMessage(channel)
-    expect(outgoing.nextOffset).toBe(1)
-    expect(channel.sent).toHaveLength(1)
-    expect(channel.sent[0]!.byteLength).toBeLessThanOrEqual(
-      AGENT_PROTOCOL_LIMITS.maximumBlobFrameBytes
-    )
+    expect(outgoing.nextOffset).toBe(channel.sent.length)
+    expect(channel.sent.length).toBeGreaterThan(1)
+    for (const frame of channel.sent) {
+      expect(frame.byteLength).toBeLessThanOrEqual(AGENT_PROTOCOL_LIMITS.maximumBlobFrameBytes)
+    }
     expect(outgoing.message).toMatchObject({
       kind: 'response',
       response: largeResponse