feat: Sync Claude Agent SDK to v0.20.2 (#1146)

Author: charlesvien

packages/agent/package.json

@@ -88,7 +88,7 @@
   },
   "dependencies": {
     "@agentclientprotocol/sdk": "^0.14.0",
-    "@anthropic-ai/claude-agent-sdk": "0.2.63",
+    "@anthropic-ai/claude-agent-sdk": "0.2.68",
     "@anthropic-ai/sdk": "^0.78.0",
     "@hono/node-server": "^1.19.9",
     "@opentelemetry/api-logs": "^0.208.0",

packages/agent/src/adapters/claude/UPSTREAM.md

@@ -5,8 +5,8 @@ Fork of `@anthropic-ai/claude-agent-acp`. Upstream repo: https://github.com/anth
 ## Fork Point
 
 - **Forked**: v0.10.9, commit `5411e0f4`, Dec 2 2025
-- **Last sync**: v0.19.2, March 2 2026
-- **SDK**: `@anthropic-ai/claude-agent-sdk` 0.2.63, `@agentclientprotocol/sdk` ^0.14.0
+- **Last sync**: v0.20.2, commit `dd9fe3a98ea494ba1982516f8aa0464b48fdd5e1`, March 6 2026
+- **SDK**: `@anthropic-ai/claude-agent-sdk` 0.2.68, `@agentclientprotocol/sdk` ^0.14.0
 
 ## File Mapping
 
@@ -55,7 +55,7 @@ Fork of `@anthropic-ai/claude-agent-acp`. Upstream repo: https://github.com/anth
 
 ## Next Sync
 
-1. Check upstream changelog since v0.19.2
+1. Check upstream changelog since v0.20.2
 2. Diff upstream source against Twig using the file mapping above
 3. Port in phases: bug fixes first, then features
 4. After each phase: `pnpm --filter agent typecheck && pnpm --filter agent build && pnpm lint`

packages/agent/src/adapters/claude/claude-agent.ts

@@ -385,14 +385,7 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
             const result = handleResultMessage(message);
             if (result.error) throw result.error;
 
-            switch (message.subtype) {
-              case "error_max_budget_usd":
-              case "error_max_turns":
-              case "error_max_structured_output_retries":
-                return { stopReason: "max_turn_requests", usage };
-              default:
-                return { stopReason: "end_turn", usage };
-            }
+            return { stopReason: result.stopReason ?? "end_turn", usage };
           }
 
           case "stream_event":
@@ -420,6 +413,14 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
               }
             }
 
+            // Skip replayed user messages that aren't pending prompts
+            if (
+              "isReplay" in message &&
+              (message as Record<string, unknown>).isReplay
+            ) {
+              break;
+            }
+
             // Store latest assistant usage (excluding subagents)
             if (
               "usage" in message.message &&
@@ -451,6 +452,8 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
           case "tool_progress":
           case "auth_status":
           case "tool_use_summary":
+          case "prompt_suggestion":
+          case "rate_limit_event":
             break;
 
           default:
@@ -459,6 +462,28 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
         }
       }
       throw new Error("Session did not end in result");
+    } catch (error) {
+      if (error instanceof RequestError || !(error instanceof Error)) {
+        throw error;
+      }
+      const msg = error.message;
+      if (
+        msg.includes("ProcessTransport") ||
+        msg.includes("terminated process") ||
+        msg.includes("process exited with") ||
+        msg.includes("process terminated by signal") ||
+        msg.includes("Failed to write to process stdin")
+      ) {
+        this.logger.error(`Process died: ${msg}`, {
+          sessionId: this.sessionId,
+        });
+        this.session.input.end();
+        throw RequestError.internalError(
+          undefined,
+          "The Claude Agent process exited unexpectedly. Please start a new session.",
+        );
+      }
+      throw error;
     } finally {
       if (!handedOff) {
         this.session.promptRunning = false;
@@ -704,6 +729,13 @@ export class ClaudeAcpAgent extends BaseAcpAgent {
       }
     } catch (err) {
       settingsManager.dispose();
+      if (
+        isResume &&
+        err instanceof Error &&
+        err.message === "Query closed before response received"
+      ) {
+        throw RequestError.resourceNotFound(sessionId);
+      }
       this.logger.error(
         isResume
           ? forkSession

packages/agent/src/adapters/claude/conversion/sdk-to-acp.ts

@@ -4,7 +4,7 @@ import type {
   SessionNotification,
   SessionUpdate,
 } from "@agentclientprotocol/sdk";
-import { RequestError } from "@agentclientprotocol/sdk";
+import { RequestError, type StopReason } from "@agentclientprotocol/sdk";
 import type {
   SDKAssistantMessage,
   SDKMessage,
@@ -574,7 +574,7 @@ export async function handleSystemMessage(
 
 export type ResultMessageHandlerResult = {
   shouldStop: boolean;
-  stopReason?: string;
+  stopReason?: StopReason;
   error?: Error;
   usage?: {
     inputTokens: number;
@@ -600,6 +600,9 @@ export function handleResultMessage(
           usage,
         };
       }
+      if ((message as Record<string, unknown>).stop_reason === "max_tokens") {
+        return { shouldStop: true, stopReason: "max_tokens", usage };
+      }
       if (message.is_error) {
         return {
           shouldStop: true,
@@ -610,6 +613,9 @@ export function handleResultMessage(
       return { shouldStop: true, stopReason: "end_turn", usage };
     }
     case "error_during_execution":
+      if ((message as Record<string, unknown>).stop_reason === "max_tokens") {
+        return { shouldStop: true, stopReason: "max_tokens", usage };
+      }
       if (message.is_error) {
         return {
           shouldStop: true,