From a3200e1aab6e67c793d6f32bc5d91d2fcad796dc Mon Sep 17 00:00:00 2001
From: Enrico Ros <enrico.ros@gmail.com>
Date: Fri, 3 Apr 2026 16:21:12 -0700
Subject: [PATCH] AIX: remove the pause_continue token stop reason, as we
 handle it in the server-side loop

---
 src/modules/aix/client/ContentReassembler.ts  |  1 -
 src/modules/aix/server/api/aix.wiretypes.ts   |  1 -
 .../chatGenerate/parsers/anthropic.parser.ts  | 32 ++++++++++---------
 tools/develop/llm-parameter-sweep/sweep.ts    |  2 +-
 4 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/src/modules/aix/client/ContentReassembler.ts b/src/modules/aix/client/ContentReassembler.ts
index 2929ee93e..821195bdb 100644
--- a/src/modules/aix/client/ContentReassembler.ts
+++ b/src/modules/aix/client/ContentReassembler.ts
@@ -819,7 +819,6 @@ export class ContentReassembler {
         // normal completions
         'ok': undefined,
         'ok-tool_invocations': undefined,
-        'ok-pause_continue': undefined,
         // issues: dialect, dispatch, or client
         'cg-issue': 'issue',
         // interruptions
diff --git a/src/modules/aix/server/api/aix.wiretypes.ts b/src/modules/aix/server/api/aix.wiretypes.ts
index 923c74d8d..b98833957 100644
--- a/src/modules/aix/server/api/aix.wiretypes.ts
+++ b/src/modules/aix/server/api/aix.wiretypes.ts
@@ -686,7 +686,6 @@ export namespace AixWire_Particles {
   export type GCTokenStopReason =
     | 'ok'                      // clean, including reaching 'stop sequences'
     | 'ok-tool_invocations'     // clean & tool invocations
-    | 'ok-pause_continue'       // clean, but paused (e.g. Anthropic server tools like web search) - requires continuation
     // premature:
     | 'cg-issue'                // [1][2] chat-generation issue (see CGIssueId, mostly a dispatch or dialect issue)
     | 'filter-content'          // content filter (e.g. profanity)
diff --git a/src/modules/aix/server/dispatch/chatGenerate/parsers/anthropic.parser.ts b/src/modules/aix/server/dispatch/chatGenerate/parsers/anthropic.parser.ts
index 31b5a56c4..fe72c1215 100644
--- a/src/modules/aix/server/dispatch/chatGenerate/parsers/anthropic.parser.ts
+++ b/src/modules/aix/server/dispatch/chatGenerate/parsers/anthropic.parser.ts
@@ -422,7 +422,7 @@ export function createAnthropicMessageParser(): ChatGenerateParseFunction {
         Object.assign(responseMessage, delta);
 
         // -> Token Stop Reason
-        const tokenStopReason = _fromAnthropicStopReason(delta.stop_reason);
+        const tokenStopReason = _fromAnthropicStopReason(delta.stop_reason, 'message_delta');
         if (tokenStopReason !== null)
           pt.setTokenStopReason(tokenStopReason);
 
@@ -638,11 +638,6 @@ export function createAnthropicMessageParserNS(): ChatGenerateParseFunction {
         needsTextSeparator = hotFixAntInjectToolsTextSpacer;
     }
 
-    // -> Token Stop Reason
-    const tokenStopReason = _fromAnthropicStopReason(stop_reason);
-    if (tokenStopReason !== null)
-      pt.setTokenStopReason(tokenStopReason);
-
     // -> Stats
     if (usage) {
       const elapsedTimeMilliseconds = Date.now() - parserCreationTimestamp;
@@ -670,6 +665,11 @@ export function createAnthropicMessageParserNS(): ChatGenerateParseFunction {
       throw new DispatchContinuationSignal(
         _createAnthropicPauseTurnContinuation(content, container?.id),
       );
+
+    // -> Token Stop Reason (pause_turn already thrown above)
+    const tokenStopReason = _fromAnthropicStopReason(stop_reason, 'parser_NS');
+    if (tokenStopReason !== null)
+      pt.setTokenStopReason(tokenStopReason);
   };
 }
 
@@ -938,7 +938,7 @@ function _createAnthropicPauseTurnContinuation(
 }
 
 
-function _fromAnthropicStopReason(stopReason: AnthropicWire_API_Message_Create.Response['stop_reason']) {
+function _fromAnthropicStopReason(stopReason: AnthropicWire_API_Message_Create.Response['stop_reason'], debugCaller: string) {
   switch (stopReason) {
 
     case 'end_turn':
@@ -948,13 +948,6 @@ function _fromAnthropicStopReason(stopReason: AnthropicWire_API_Message_Create.R
     case 'tool_use':
       return 'ok-tool_invocations';
 
-    /**
-     * https://docs.claude.com/en/api/handling-stop-reasons#pause-turn
-     * Used with server tools like web search when Claude needs to pause a long-running operation.
-     */
-    case 'pause_turn':
-      return 'ok-pause_continue';
-
     case 'max_tokens':
       return 'out-of-tokens';
 
@@ -964,8 +957,17 @@ function _fromAnthropicStopReason(stopReason: AnthropicWire_API_Message_Create.R
     case 'refusal':
       return 'filter-refusal'; // Safety concerns - refusal to answer
 
+    case 'pause_turn':
+      // pause_turn hits this function from message_delta, but the return is irrelevant -
+      // message_stop will throw DispatchContinuationSignal before the tokenStopReason matters
+      // https://docs.claude.com/en/api/handling-stop-reasons#pause-turn
+      return null;
+
     default:
-      console.warn(`_fromAnthropicStopReason: unknown stop reason: ${stopReason}`);
+      const _exhaustiveCheck: never = stopReason;
+      // fallthrough
+    case null:
+      console.warn(`_fromAnthropicStopReason(${debugCaller}): unexpected stop_reason: ${stopReason}`);
       return null;
   }
 }
diff --git a/tools/develop/llm-parameter-sweep/sweep.ts b/tools/develop/llm-parameter-sweep/sweep.ts
index a80f178ab..9c3520155 100644
--- a/tools/develop/llm-parameter-sweep/sweep.ts
+++ b/tools/develop/llm-parameter-sweep/sweep.ts
@@ -503,7 +503,7 @@ async function testParameterValue(
 
     // Check tokenStopReason for non-ok outcomes
     const stopReason = collector.tokenStopReason;
-    const isValidStop = !stopReason || stopReason === 'ok' || stopReason === 'ok-tool_invocations' || stopReason === 'ok-pause_continue';
+    const isValidStop = !stopReason || stopReason === 'ok' || stopReason === 'ok-tool_invocations';
     const isTruncated = stopReason === 'out-of-tokens';
 
     const preview = collector.hasText