From 624733d631ac3197afa4f9aa701f56f184fdde69 Mon Sep 17 00:00:00 2001
From: Aldehir Rojas <hello@alde.dev>
Date: Tue, 31 Mar 2026 06:52:42 -0500
Subject: [PATCH] common : gpt-oss handle builtin and unsolicited tool calls
 (#21213)

---
 common/chat.cpp     |  6 +++++-
 tests/test-chat.cpp | 21 +++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/common/chat.cpp b/common/chat.cpp
index bf43087285..c2ca17c743 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -989,6 +989,10 @@ static common_chat_params common_chat_params_init_gpt_oss(const common_chat_temp
         auto analysis = p.ref("analysis");
         auto preamble = p.rule("preamble", p.literal("<|channel|>commentary<|message|>") + p.content(content) + end);
         auto final_msg = p.rule("final", p.literal("<|channel|>final<|message|>") + p.content(content));
+
+        // Consume any unsolicited tool calls, e.g. builtin functions
+        auto unsolicited = p.rule("unsolicited", p.atomic(p.optional(channel) + p.literal(" to=") + content + end));
+
         auto any = p.rule("any", preamble | analysis);
 
         if (has_response_format) {
@@ -1032,7 +1036,7 @@ static common_chat_params common_chat_params_init_gpt_oss(const common_chat_temp
             return p.zero_or_more(start + any) + start + (tool_call | final_msg);
         }
 
-        return p.zero_or_more(start + any) + start + final_msg;
+        return p.zero_or_more(start + any) + start + (final_msg | unsolicited);
     });
 
     data.parser = parser.save();
diff --git a/tests/test-chat.cpp b/tests/test-chat.cpp
index 6e11252e12..1c4da68195 100644
--- a/tests/test-chat.cpp
+++ b/tests/test-chat.cpp
@@ -3077,6 +3077,27 @@ static void test_template_output_peg_parsers(bool detailed_debug) {
             .expect_reasoning("I need to output the invoice details in JSON")
             .expect_content(R"({"amount": 123.45, "date": "2025-12-03"})")
             .run();
+
+
+        // Unsolicited tool calls. There is no good way to handle these, so we return empty content.
+
+        // Builtin function - recipient in role
+        tst.test(
+               "<|channel|>analysis<|message|>I will execute python to say hello<|end|>"
+               "<|start|>assistant to=container.exec<|channel|>commentary<|message|>python3 -c 'print(\"hello\")'")
+            .reasoning_format(COMMON_REASONING_FORMAT_AUTO)
+            .expect_reasoning("I will execute python to say hello")
+            .expect_content("")
+            .run();
+
+        // Builtin function - recipient in channel
+        tst.test(
+               "<|channel|>analysis<|message|>I will execute python to say hello<|end|>"
+               "<|start|>assistant<|channel|>commentary to=python <|constrain|>code<|message|>print(\"hello\")")
+            .reasoning_format(COMMON_REASONING_FORMAT_AUTO)
+            .expect_reasoning("I will execute python to say hello")
+            .expect_content("")
+            .run();
     }
 
     {