fix(inference): preserve Gemini thought_signature across tool-call turns (TAURI-RUST-4PK) (#3548) (#3553)

src/openhuman/agent/dispatcher_tests.rs

@@ -26,6 +26,7 @@ fn native_dispatcher_roundtrip() {
             id: "tc1".into(),
             name: "file_read".into(),
             arguments: "{\"path\":\"a.txt\"}".into(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,
@@ -268,6 +269,7 @@ fn assistant_tool_calls(id: &str) -> ConversationMessage {
             id: id.into(),
             name: "shell".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }],
         reasoning_content: None,
     }
@@ -397,6 +399,7 @@ fn assistant_tool_calls_multi(ids: &[&str]) -> ConversationMessage {
                 id: (*id).into(),
                 name: "shell".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             })
             .collect(),
         reasoning_content: None,
@@ -413,6 +416,7 @@ fn native_dispatcher_serializes_reasoning_content_for_tool_call_turns() {
                 id: "tc-1".into(),
                 name: "shell".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: Some("chain-of-thought replay blob".into()),
         },

src/openhuman/agent/harness/bughunt_tests.rs

@@ -80,6 +80,7 @@ async fn native_tool_call_decodes_json_encoded_arguments_string() {
             id: "c1".into(),
             name: "captured".into(),
             arguments: "{\"city\":\"Berlin\",\"n\":3}".to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,
@@ -143,6 +144,7 @@ async fn documents_silent_drop_of_non_json_arguments_string() {
             name: "captured".into(),
             // Not valid JSON — the model "meant" a plain string.
             arguments: "world".to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,
@@ -353,6 +355,7 @@ async fn native_tool_calls_take_precedence_over_xml_in_text() {
             id: "c1".into(),
             name: "tool_a".into(),
             arguments: "{\"src\":\"native\"}".into(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,

src/openhuman/agent/harness/parse_tests.rs

@@ -261,6 +261,7 @@ fn structured_tool_call_and_history_helpers_round_trip_expected_shapes() {
         id: "call-1".into(),
         name: "echo".into(),
         arguments: "{\"value\":\"hello\"}".into(),
+        extra_content: None,
     }];
 
     let parsed = parse_structured_tool_calls(&tool_calls);

src/openhuman/agent/harness/session/runtime.rs

@@ -456,6 +456,8 @@ impl Agent {
                     .unwrap_or_else(|| format!("parsed-{}-{}", iteration + 1, idx + 1)),
                 name: call.name.clone(),
                 arguments: call.arguments.to_string(),
+                // Prompt-based tool calls carry no provider extra_content.
+                extra_content: None,
             })
             .collect()
     }

src/openhuman/agent/harness/session/runtime_tests.rs

@@ -312,6 +312,7 @@ fn helper_paths_cover_no_overlap_native_calls_and_truncation() {
         id: "native-1".into(),
         name: "echo".into(),
         arguments: "{}".into(),
+        extra_content: None,
     }];
     let response = crate::openhuman::inference::provider::ChatResponse {
         text: Some(String::new()),

src/openhuman/agent/harness/session/tests.rs

@@ -461,6 +461,7 @@ async fn turn_with_native_dispatcher_handles_tool_results_variant() {
                     id: "tc1".into(),
                     name: "echo".into(),
                     arguments: "{}".into(),
+                    extra_content: None,
                 }],
                 usage: None,
                 reasoning_content: None,
@@ -604,6 +605,7 @@ async fn turn_dispatches_spawn_subagent_through_full_path() {
                         "prompt": "find out about X"
                     })
                     .to_string(),
+                    extra_content: None,
                 }],
                 usage: None,
                 reasoning_content: None,

src/openhuman/agent/harness/session/turn_engine_adapter.rs

@@ -78,6 +78,9 @@ fn persisted_tool_calls(
                 id,
                 name: c.name.clone(),
                 arguments: c.arguments.to_string(),
+                // Prompt-parsed calls carry no provider extra_content; the
+                // native (Gemini) path returns early above, preserving it.
+                extra_content: None,
             }
         })
         .collect()

src/openhuman/agent/harness/session/turn_tests.rs

@@ -414,6 +414,7 @@ fn trim_history_snaps_past_orphaned_tool_results() {
                 id: "call_x".into(),
                 name: "shell".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         },

src/openhuman/agent/harness/subagent_runner/ops_tests.rs

@@ -302,6 +302,7 @@ fn tool_response(name: &str, args: &str) -> ChatResponse {
             id: "call-1".into(),
             name: name.into(),
             arguments: args.into(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,

src/openhuman/agent/harness/test_support.rs

@@ -263,6 +263,7 @@ impl Provider for KeywordScriptedProvider {
                             id: format!("call_{id}"),
                             name: c.name.clone(),
                             arguments: c.arguments.to_string(),
+                            extra_content: None,
                         }
                     })
                     .collect()

src/openhuman/agent/harness/token_budget.rs

@@ -372,6 +372,7 @@ mod tests {
                 id: "1".into(),
                 name: "echo".into(),
                 arguments: "{\"value\":\"x\"}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         };
@@ -396,6 +397,7 @@ mod tests {
             id: id.into(),
             name: "f".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }
     }
 

src/openhuman/agent/harness/tool_loop_tests.rs

@@ -398,6 +398,7 @@ async fn run_tool_call_loop_persists_native_tool_results_as_tool_messages() {
                     id: "call-1".into(),
                     name: "echo".into(),
                     arguments: "{}".into(),
+                    extra_content: None,
                 }],
                 usage: None,
                 reasoning_content: None,

src/openhuman/agent/tests.rs

@@ -382,6 +382,7 @@ async fn turn_executes_single_tool_then_returns() {
             id: "tc1".into(),
             name: "echo".into(),
             arguments: r#"{"message": "hello from tool"}"#.into(),
+            extra_content: None,
         }]),
         text_response("I ran the tool"),
     ]));
@@ -412,16 +413,19 @@ async fn turn_handles_multi_step_tool_chain() {
             id: "tc1".into(),
             name: "counter".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         tool_response(vec![ToolCall {
             id: "tc2".into(),
             name: "counter".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         tool_response(vec![ToolCall {
             id: "tc3".into(),
             name: "counter".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         text_response("Done after 3 calls"),
     ]));
@@ -460,6 +464,7 @@ async fn turn_emits_checkpoint_at_max_iterations() {
             id: format!("tc{i}"),
             name: "echo".into(),
             arguments: r#"{"message": "loop"}"#.into(),
+            extra_content: None,
         }]));
     }
 
@@ -504,6 +509,7 @@ async fn turn_handles_unknown_tool_gracefully() {
             id: "tc1".into(),
             name: "nonexistent_tool".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         text_response("I couldn't find that tool"),
     ]));
@@ -544,6 +550,7 @@ async fn turn_recovers_from_tool_failure() {
             id: "tc1".into(),
             name: "fail".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         text_response("Tool failed but I recovered"),
     ]));
@@ -568,6 +575,7 @@ async fn turn_recovers_from_tool_error() {
             id: "tc1".into(),
             name: "panicker".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }]),
         text_response("I recovered from the error"),
     ]));
@@ -794,6 +802,7 @@ async fn turn_preserves_text_alongside_tool_calls() {
                 id: "tc1".into(),
                 name: "echo".into(),
                 arguments: r#"{"message": "hi"}"#.into(),
+                extra_content: None,
             }],
             usage: None,
             reasoning_content: None,
@@ -835,16 +844,19 @@ async fn turn_handles_multiple_tools_in_one_response() {
                 id: "tc1".into(),
                 name: "counter".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             },
             ToolCall {
                 id: "tc2".into(),
                 name: "counter".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             },
             ToolCall {
                 id: "tc3".into(),
                 name: "counter".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             },
         ]),
         text_response("All 3 done"),
@@ -982,6 +994,7 @@ async fn history_contains_all_expected_entries_after_tool_loop() {
             id: "tc1".into(),
             name: "echo".into(),
             arguments: r#"{"message": "tool-out"}"#.into(),
+            extra_content: None,
         }]),
         text_response("final answer"),
     ]));
@@ -1087,6 +1100,7 @@ async fn native_dispatcher_handles_stringified_arguments() {
             id: "tc1".into(),
             name: "echo".into(),
             arguments: r#"{"message": "hello"}"#.into(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,
@@ -1176,6 +1190,7 @@ fn conversation_message_serialization_roundtrip() {
                 id: "tc1".into(),
                 name: "shell".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: Some("thinking".into()),
         },
@@ -1302,6 +1317,7 @@ fn xml_dispatcher_converts_history_to_provider_messages() {
                 id: "tc1".into(),
                 name: "shell".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         },
@@ -1337,11 +1353,13 @@ fn native_dispatcher_converts_tool_results_to_tool_messages() {
                     id: "tc1".into(),
                     name: "shell".into(),
                     arguments: "{}".into(),
+                    extra_content: None,
                 },
                 ToolCall {
                     id: "tc2".into(),
                     name: "shell".into(),
                     arguments: "{}".into(),
+                    extra_content: None,
                 },
             ],
             reasoning_content: None,

src/openhuman/agent_orchestration/tools/spawn_parallel_agents_tests.rs

@@ -500,6 +500,7 @@ fn tool_response(name: &str, arguments: serde_json::Value) -> ChatResponse {
             id: format!("call-{name}"),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,

src/openhuman/context/manager_tests.rs

@@ -14,6 +14,7 @@ fn call(id: &str) -> ConversationMessage {
             id: id.into(),
             name: "t".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }],
         reasoning_content: None,
     }

src/openhuman/context/microcompact.rs

@@ -115,6 +115,7 @@ mod tests {
                 id: id.into(),
                 name: name.into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         }

src/openhuman/context/pipeline.rs

@@ -269,6 +269,7 @@ mod tests {
                 id: id.into(),
                 name: "t".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         }

src/openhuman/context/summarizer_tests.rs

@@ -18,6 +18,7 @@ fn call(id: &str) -> ConversationMessage {
             id: id.into(),
             name: "t".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }],
         reasoning_content: None,
     }
@@ -217,6 +218,7 @@ fn transcript_renders_all_message_variants() {
                 id: "1".into(),
                 name: "shell".into(),
                 arguments: r#"{"cmd":"ls"}"#.into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         },

src/openhuman/inference/provider/claude_code/event_mapper.rs

@@ -251,6 +251,8 @@ impl EventMapper {
                 id: call_id,
                 name,
                 arguments,
+                // Claude Code CLI events carry no OpenAI-compat extra_content.
+                extra_content: None,
             });
         }
         Vec::new()

src/openhuman/inference/provider/compatible_helpers.rs

@@ -199,6 +199,9 @@ impl OpenAiCompatibleProvider {
                                                     tc.arguments,
                                                 )),
                                             }),
+                                            // Echo Gemini's thought_signature back on
+                                            // the next turn (TAURI-RUST-4PK).
+                                            extra_content: tc.extra_content,
                                         })
                                         .collect::<Vec<_>>();
 
@@ -405,6 +408,10 @@ impl OpenAiCompatibleProvider {
                     id: tc.id.unwrap_or_else(|| uuid::Uuid::new_v4().to_string()),
                     name,
                     arguments,
+                    // Preserve Gemini's thought_signature (TAURI-RUST-4PK) so it
+                    // can be echoed on the next turn; None for providers that
+                    // don't send extra_content.
+                    extra_content: tc.extra_content,
                 })
             })
             .collect::<Vec<_>>();
@@ -420,6 +427,8 @@ impl OpenAiCompatibleProvider {
                         id: uuid::Uuid::new_v4().to_string(),
                         name: name.clone(),
                         arguments: normalize_function_arguments(function.arguments.clone()),
+                        // Legacy `function_call` shape carries no extra_content.
+                        extra_content: None,
                     });
                 }
             }

src/openhuman/inference/provider/compatible_parse.rs

@@ -156,6 +156,9 @@ pub(crate) fn parse_provider_tool_call_from_value(
                 arguments: normalize_function_arguments(Some(serde_json::Value::String(
                     call.arguments,
                 ))),
+                // Preserve Gemini's thought_signature through the stored-history
+                // recovery path so it is echoed on the next turn (TAURI-RUST-4PK).
+                extra_content: call.extra_content,
             });
         }
     }
@@ -176,6 +179,9 @@ pub(crate) fn parse_provider_tool_call_from_value(
         id,
         name: name.to_string(),
         arguments: normalize_function_arguments(function.get("arguments").cloned()),
+        // Carry Gemini's thought_signature if the stored value had one
+        // (TAURI-RUST-4PK).
+        extra_content: value.get("extra_content").cloned(),
     })
 }
 

src/openhuman/inference/provider/compatible_provider_impl.rs

@@ -438,6 +438,9 @@ impl Provider for OpenAiCompatibleProvider {
                     id: tc.id.unwrap_or_else(|| uuid::Uuid::new_v4().to_string()),
                     name,
                     arguments,
+                    // Non-streaming response: preserve Gemini's thought_signature
+                    // so it round-trips on the next turn (TAURI-RUST-4PK).
+                    extra_content: tc.extra_content,
                 })
             })
             .collect::<Vec<_>>();

src/openhuman/inference/provider/compatible_stream_native.rs

@@ -254,6 +254,16 @@ impl OpenAiCompatibleProvider {
                                 let idx = tc.index.unwrap_or(0);
                                 let entry = tool_accum.entry(idx).or_default();
 
+                                // Capture the first non-null extra_content seen for
+                                // this index (Gemini's thought_signature, TAURI-RUST-4PK).
+                                if entry.extra_content.is_none() {
+                                    if let Some(ec) = tc.extra_content.as_ref() {
+                                        if !ec.is_null() {
+                                            entry.extra_content = Some(ec.clone());
+                                        }
+                                    }
+                                }
+
                                 if let Some(id) = tc.id.as_ref() {
                                     if entry.id.is_none() {
                                         log::debug!(
@@ -380,6 +390,9 @@ impl OpenAiCompatibleProvider {
                         )
                     },
                 }),
+                // Carry Gemini's thought_signature through to parse_native_response
+                // so it lands on the harness ToolCall (TAURI-RUST-4PK).
+                extra_content: c.extra_content,
             })
             .collect();
 

src/openhuman/inference/provider/compatible_tests.rs

@@ -1157,6 +1157,7 @@ fn parse_native_response_preserves_tool_call_id() {
                     r#"{"command":"pwd"}"#.to_string(),
                 )),
             }),
+            extra_content: None,
         }]),
         function_call: None,
         reasoning_content: None,
@@ -1183,6 +1184,7 @@ fn parse_native_response_captures_reasoning_content() {
                 name: Some("shell".to_string()),
                 arguments: Some(serde_json::Value::String("{}".to_string())),
             }),
+            extra_content: None,
         }]),
         function_call: None,
         reasoning_content: Some("  weighing the options  ".to_string()),
@@ -1234,6 +1236,189 @@ fn convert_messages_for_native_maps_tool_result_payload() {
     );
 }
 
+// ── TAURI-RUST-4PK: Gemini thought_signature round-trip ──────────────────────
+
+/// The wire `ToolCall` must capture Gemini's `extra_content` from the response
+/// and re-emit it verbatim on the request, so the thought_signature survives the
+/// round-trip. A tool call without it omits the field entirely (non-Gemini
+/// providers stay byte-identical on the wire).
+#[test]
+fn tool_call_wire_round_trips_extra_content() {
+    let json = r#"{"id":"call_g","type":"function","function":{"name":"shell","arguments":"{}"},"extra_content":{"google":{"thought_signature":"SIG123"}}}"#;
+    let tc: ToolCall = serde_json::from_str(json).unwrap();
+    assert_eq!(
+        tc.extra_content
+            .as_ref()
+            .and_then(|v| v.pointer("/google/thought_signature"))
+            .and_then(|v| v.as_str()),
+        Some("SIG123"),
+        "extra_content must be captured from the Gemini response"
+    );
+    let reemitted = serde_json::to_value(&tc).unwrap();
+    assert_eq!(
+        reemitted
+            .pointer("/extra_content/google/thought_signature")
+            .and_then(|v| v.as_str()),
+        Some("SIG123"),
+        "extra_content must be echoed verbatim on the request body"
+    );
+
+    let bare: ToolCall = serde_json::from_str(
+        r#"{"id":"c","type":"function","function":{"name":"x","arguments":"{}"}}"#,
+    )
+    .unwrap();
+    assert!(bare.extra_content.is_none());
+    assert!(
+        serde_json::to_value(&bare)
+            .unwrap()
+            .get("extra_content")
+            .is_none(),
+        "providers that don't send extra_content keep a byte-identical wire body"
+    );
+}
+
+/// `parse_native_response` lifts the tool-call `extra_content` onto the harness
+/// ToolCall so it can be persisted and echoed (TAURI-RUST-4PK).
+#[test]
+fn parse_native_response_captures_tool_call_extra_content() {
+    let message = ResponseMessage {
+        content: None,
+        tool_calls: Some(vec![ToolCall {
+            id: Some("call_g".to_string()),
+            kind: Some("function".to_string()),
+            function: Some(Function {
+                name: Some("shell".to_string()),
+                arguments: Some(serde_json::Value::String("{}".to_string())),
+            }),
+            extra_content: Some(serde_json::json!({"google":{"thought_signature":"SIG_RESP"}})),
+        }]),
+        function_call: None,
+        reasoning_content: None,
+    };
+    let parsed =
+        OpenAiCompatibleProvider::parse_native_response(wrap_message(message), "google").unwrap();
+    assert_eq!(parsed.tool_calls.len(), 1);
+    assert_eq!(
+        parsed.tool_calls[0]
+            .extra_content
+            .as_ref()
+            .and_then(|v| v.pointer("/google/thought_signature"))
+            .and_then(|v| v.as_str()),
+        Some("SIG_RESP"),
+        "the signature must land on the harness ToolCall"
+    );
+}
+
+/// On rebuild, a persisted assistant tool-call message whose stored JSON carries
+/// `extra_content` must re-emit it on the wire tool_calls, so Gemini sees the
+/// signature on the follow-up turn (TAURI-RUST-4PK).
+#[test]
+fn convert_messages_for_native_echoes_tool_call_extra_content() {
+    let input = vec![
+        ChatMessage::assistant(
+            r#"{"content":"on it","tool_calls":[{"id":"call_g","name":"shell","arguments":"{}","extra_content":{"google":{"thought_signature":"SIG_ECHO"}}}]}"#,
+        ),
+        ChatMessage::tool(r#"{"tool_call_id":"call_g","content":"done"}"#),
+    ];
+    let converted = OpenAiCompatibleProvider::convert_messages_for_native(&input);
+    let tool_calls = converted[0]
+        .tool_calls
+        .as_ref()
+        .expect("assistant tool_calls present");
+    assert_eq!(
+        tool_calls[0]
+            .extra_content
+            .as_ref()
+            .and_then(|v| v.pointer("/google/thought_signature"))
+            .and_then(|v| v.as_str()),
+        Some("SIG_ECHO"),
+        "stored extra_content must be echoed back on the rebuilt request"
+    );
+    assert_eq!(
+        serde_json::to_value(tool_calls)
+            .unwrap()
+            .pointer("/0/extra_content/google/thought_signature")
+            .and_then(|v| v.as_str()),
+        Some("SIG_ECHO"),
+        "echoed signature must appear on the serialized wire body"
+    );
+}
+
+/// A non-Gemini stored tool call (no `extra_content`) rebuilds with the field
+/// omitted — every other provider's wire body stays byte-identical.
+#[test]
+fn convert_messages_for_native_tool_call_without_extra_content_stays_none() {
+    let input = vec![
+        ChatMessage::assistant(
+            r#"{"content":"on it","tool_calls":[{"id":"call_x","name":"shell","arguments":"{}"}]}"#,
+        ),
+        ChatMessage::tool(r#"{"tool_call_id":"call_x","content":"done"}"#),
+    ];
+    let converted = OpenAiCompatibleProvider::convert_messages_for_native(&input);
+    let tool_calls = converted[0]
+        .tool_calls
+        .as_ref()
+        .expect("assistant tool_calls present");
+    assert!(tool_calls[0].extra_content.is_none());
+    assert!(serde_json::to_value(&tool_calls[0])
+        .unwrap()
+        .get("extra_content")
+        .is_none());
+}
+
+/// Streaming: Gemini sends the thought_signature in the tool-call delta's
+/// `extra_content` on the first chunk. The accumulator must preserve it onto the
+/// aggregated tool call so it reaches history (TAURI-RUST-4PK).
+#[tokio::test]
+async fn streaming_tool_call_captures_extra_content() {
+    let mock_server = MockServer::start().await;
+    let body = "data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"call_g\",\"type\":\"function\",\"function\":{\"name\":\"shell\",\"arguments\":\"{}\"},\"extra_content\":{\"google\":{\"thought_signature\":\"SIG_STREAM\"}}}]}}]}\n\n\
+                data: [DONE]\n\n";
+    Mock::given(method("POST"))
+        .and(path("/chat/completions"))
+        .respond_with(ResponseTemplate::new(200).set_body_raw(body, "text/event-stream"))
+        .mount(&mock_server)
+        .await;
+
+    let provider =
+        OpenAiCompatibleProvider::new("google", &mock_server.uri(), None, AuthStyle::None);
+    let request = NativeChatRequest {
+        model: "models/gemini-3.5-flash".to_string(),
+        messages: vec![NativeMessage {
+            role: "user".to_string(),
+            content: Some("hi".into()),
+            tool_call_id: None,
+            tool_calls: None,
+            reasoning_content: None,
+        }],
+        temperature: Some(0.7),
+        stream: Some(true),
+        tools: None,
+        tool_choice: None,
+        thread_id: None,
+        stream_options: Some(super::compatible_types::OpenAiStreamOptions {
+            include_usage: true,
+        }),
+        options: None,
+        frequency_penalty: None,
+    };
+    let (delta_tx, _delta_rx) = tokio::sync::mpsc::channel(64);
+    let resp = provider
+        .stream_native_chat(None, &request, &delta_tx, 0)
+        .await
+        .unwrap();
+    assert_eq!(resp.tool_calls.len(), 1);
+    assert_eq!(
+        resp.tool_calls[0]
+            .extra_content
+            .as_ref()
+            .and_then(|v| v.pointer("/google/thought_signature"))
+            .and_then(|v| v.as_str()),
+        Some("SIG_STREAM"),
+        "streaming must preserve the thought_signature onto the aggregated tool call"
+    );
+}
+
 /// Helper: roles in serialized order.
 fn roles(messages: &[NativeMessage]) -> Vec<&str> {
     messages.iter().map(|m| m.role.as_str()).collect()
@@ -1550,6 +1735,7 @@ fn enforce_invariants_clears_reasoning_when_assistant_collapses_to_text() {
                     name: Some("web_fetch".to_string()),
                     arguments: Some(serde_json::Value::String("{}".to_string())),
                 }),
+                extra_content: None,
             }]),
             reasoning_content: Some("deep reasoning".to_string()),
         },
@@ -1897,6 +2083,7 @@ fn response_with_tool_call_object_arguments_deserializes() {
                     name: Some("get_weather".to_string()),
                     arguments: Some(serde_json::json!({"location":"London","unit":"c"})),
                 }),
+                extra_content: None,
             }]),
             function_call: None,
         }),

src/openhuman/inference/provider/compatible_types.rs

@@ -411,6 +411,20 @@ pub(crate) struct ToolCall {
     #[serde(rename = "type")]
     pub(crate) kind: Option<String>,
     pub(crate) function: Option<Function>,
+    /// Provider-specific passthrough metadata attached to a tool call.
+    ///
+    /// Google's Gemini OpenAI-compat endpoint returns a cryptographically
+    /// signed reasoning token here as
+    /// `extra_content.google.thought_signature`, and **requires** it echoed
+    /// back verbatim on the assistant tool-call turn of every subsequent
+    /// request — otherwise it 400s with "Function call is missing a
+    /// thought_signature" (TAURI-RUST-4PK). Captured on the response and
+    /// re-emitted on the request as an opaque value so any future
+    /// `extra_content.*` keys round-trip unchanged. `skip_serializing_if`
+    /// keeps the wire body byte-identical for every provider that doesn't
+    /// send it.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub(crate) extra_content: Option<serde_json::Value>,
 }
 
 #[derive(Debug, Clone, Deserialize, Serialize)]
@@ -517,6 +531,12 @@ pub(crate) struct StreamToolCallDelta {
     pub(crate) kind: Option<String>,
     #[serde(default)]
     pub(crate) function: Option<StreamToolCallFunction>,
+    /// Provider passthrough metadata (Gemini's `extra_content`, carrying
+    /// `google.thought_signature`). Arrives on the first chunk for a given
+    /// tool-call index; accumulated and re-emitted so the signature survives
+    /// the streaming path (TAURI-RUST-4PK).
+    #[serde(default)]
+    pub(crate) extra_content: Option<serde_json::Value>,
 }
 
 #[derive(Debug, Deserialize)]
@@ -545,4 +565,8 @@ pub(crate) struct StreamingToolCall {
     pub(crate) arguments: String,
     pub(crate) emitted_start: bool,
     pub(crate) emitted_chars: usize,
+    /// First non-null `extra_content` seen for this tool-call index (Gemini's
+    /// thought_signature). Re-emitted on the aggregated [`ToolCall`] so it can
+    /// be echoed on the next turn (TAURI-RUST-4PK).
+    pub(crate) extra_content: Option<serde_json::Value>,
 }

src/openhuman/inference/provider/traits.rs

@@ -59,6 +59,14 @@ pub struct ToolCall {
     pub id: String,
     pub name: String,
     pub arguments: String,
+    /// Provider-specific passthrough metadata for this call, captured from the
+    /// response and echoed back verbatim on the next assistant turn. Carries
+    /// Google Gemini's required `extra_content.google.thought_signature` so
+    /// multi-turn tool calling round-trips without a 400 (TAURI-RUST-4PK).
+    /// `None`/omitted for every provider that doesn't emit it, so non-Gemini
+    /// history stays byte-identical.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub extra_content: Option<serde_json::Value>,
 }
 
 /// Token usage information returned by the provider after an inference call.

src/openhuman/inference/provider/traits_tests.rs

@@ -55,6 +55,7 @@ fn chat_response_helpers() {
             id: "1".into(),
             name: "shell".into(),
             arguments: "{}".into(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,
@@ -69,6 +70,7 @@ fn tool_call_serialization() {
         id: "call_123".into(),
         name: "file_read".into(),
         arguments: r#"{"path":"test.txt"}"#.into(),
+        extra_content: None,
     };
     let json = serde_json::to_string(&tc).unwrap();
     assert!(json.contains("call_123"));

src/openhuman/workflows/e2e_plumbing_tests.rs

@@ -86,6 +86,7 @@ fn tool_call(id: &str, name: &str, args: serde_json::Value) -> ChatResponse {
             id: id.into(),
             name: name.into(),
             arguments: args.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,

src/openhuman/workflows/e2e_run_tests.rs

@@ -97,6 +97,7 @@ fn tool_call_resp(id: &str, name: &str, args: serde_json::Value) -> ChatResponse
             id: id.into(),
             name: name.into(),
             arguments: args.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: None,

tests/agent_archivist_debug_round21_raw_coverage_e2e.rs

@@ -223,6 +223,7 @@ fn tool_response(name: &str, arguments: serde_json::Value) -> ChatResponse {
             id: "round21-call".to_string(),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: Some("scripted tool use".to_string()),

tests/agent_harness_leftovers_raw_coverage_e2e.rs

@@ -262,6 +262,7 @@ fn tool_response(id: &str, name: &str, arguments: serde_json::Value) -> ChatResp
             id: id.to_string(),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: Some(UsageInfo {
             input_tokens: 7,

tests/agent_harness_raw_coverage_e2e.rs

@@ -187,6 +187,7 @@ fn tool_call(id: &str, name: &str, arguments: serde_json::Value) -> ToolCall {
         id: id.to_string(),
         name: name.to_string(),
         arguments: arguments.to_string(),
+        extra_content: None,
     }
 }
 

tests/agent_prompts_subagent_raw_coverage_e2e.rs

@@ -225,6 +225,7 @@ fn tool_response(name: &str, arguments: serde_json::Value) -> ChatResponse {
             id: "round18-call".to_string(),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: Some("test reasoning".to_string()),

tests/agent_session_turn_raw_coverage_e2e.rs

@@ -487,6 +487,7 @@ fn native_tool_response(id: &str, name: &str, args: serde_json::Value) -> ChatRe
             id: id.to_string(),
             name: name.to_string(),
             arguments: args.to_string(),
+            extra_content: None,
         }],
         usage: Some(UsageInfo {
             input_tokens: 21,

tests/agent_tool_loop_raw_coverage_e2e.rs

@@ -330,6 +330,7 @@ fn native_tool_response(name: &str, arguments: serde_json::Value) -> ChatRespons
             id: format!("call-{name}"),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: Some(UsageInfo {
             input_tokens: 13,

tests/agent_turn_builder_leftovers_raw_coverage_e2e.rs

@@ -290,6 +290,7 @@ fn native_tool_response(name: &str, arguments: &str) -> ChatResponse {
             id: "round20-native-1".to_string(),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: Some(UsageInfo {
             input_tokens: 7_000,

tests/calendar_grounding_e2e.rs

@@ -53,6 +53,7 @@ impl Provider for MockCalendarProvider {
                         "timeMax": "2026-05-04T00:00:00Z"
                     })
                     .to_string(),
+                    extra_content: None,
                 }],
                 usage: None,
                 reasoning_content: None,

tests/composio_list_tools_stack_overflow_regression.rs

@@ -218,6 +218,7 @@ impl Provider for StubProvider {
                     id: "call_1".into(),
                     name: "composio_list_tools".into(),
                     arguments: json!({ "toolkits": ["gmail"] }).to_string(),
+                    extra_content: None,
                 }],
                 usage: None,
                 reasoning_content: None,

tests/inference_agent_raw_coverage_e2e.rs

@@ -3798,11 +3798,13 @@ fn agent_dispatchers_and_host_runtime_cover_public_edge_paths() {
                 id: "call-ok".into(),
                 name: "search_docs".into(),
                 arguments: "{\"query\":\"native\"}".into(),
+                extra_content: None,
             },
             ToolCall {
                 id: "call-bad-json".into(),
                 name: "search_docs".into(),
                 arguments: "{not-json".into(),
+                extra_content: None,
             },
         ],
         ..Default::default()
@@ -3835,6 +3837,7 @@ fn agent_dispatchers_and_host_runtime_cover_public_edge_paths() {
                 id: "call-1".into(),
                 name: "search_docs".into(),
                 arguments: "{\"query\":\"paired\"}".into(),
+                extra_content: None,
             }],
             reasoning_content: Some("thinking".into()),
         },
@@ -3848,6 +3851,7 @@ fn agent_dispatchers_and_host_runtime_cover_public_edge_paths() {
                 id: "missing-result".into(),
                 name: "search_docs".into(),
                 arguments: "{}".into(),
+                extra_content: None,
             }],
             reasoning_content: None,
         },

tests/inference_provider_admin_round22_raw_coverage_e2e.rs

@@ -671,6 +671,7 @@ impl Provider for Round22Provider {
                 id: "round22-call".to_string(),
                 name: "round22_tool".to_string(),
                 arguments: "{}".to_string(),
+                extra_content: None,
             }],
             usage: None,
             reasoning_content: None,

tests/monitor_agent_e2e.rs

@@ -218,6 +218,7 @@ fn tool_response(id: &str, name: &str, arguments: serde_json::Value) -> ChatResp
             id: id.to_string(),
             name: name.to_string(),
             arguments: arguments.to_string(),
+            extra_content: None,
         }],
         usage: None,
         reasoning_content: Some(format!("need {name}")),

tests/tools_agent_credentials_state_raw_coverage_e2e.rs

@@ -725,6 +725,7 @@ async fn round16_agent_builder_turn_uses_public_harness_paths() {
                 id: "call-round16".into(),
                 name: "echo".into(),
                 arguments: json!({ "message": "builder" }).to_string(),
+                extra_content: None,
             }],
         ),
         response(Some("builder final"), Vec::new()),