[router] add harmony tool parser base structure and interface (#11036)

sgl-router/src/tool_parser/parsers/gpt_oss_harmony_parser.rs

@@ -0,0 +1,70 @@
+use async_trait::async_trait;
+
+use crate::tool_parser::{
+    errors::ToolParserResult,
+    state::ParseState,
+    traits::{TokenToolParser, ToolParser},
+    types::{StreamResult, ToolCall},
+};
+
+/// Placeholder for the Harmony-backed GPT-OSS parser.
+///
+/// regex implementation. This struct will be fleshed out in subsequent phases to
+/// reuse Harmony's tokenizer and message reconstruction logic.
+#[derive(Default)]
+pub struct GptOssHarmonyParser;
+
+impl GptOssHarmonyParser {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+#[async_trait]
+impl ToolParser for GptOssHarmonyParser {
+    async fn parse_complete(&self, output: &str) -> ToolParserResult<(String, Vec<ToolCall>)> {
+        // Temporary stub: fall back to returning the raw text with no tool calls.
+        // Later phases will decode Harmony tokens into structured tool calls.
+        Ok((output.to_string(), Vec::new()))
+    }
+
+    async fn parse_incremental(
+        &self,
+        _chunk: &str,
+        _state: &mut ParseState,
+    ) -> ToolParserResult<StreamResult> {
+        // Temporary stub until the Harmony streaming pipeline is implemented.
+        Ok(StreamResult::Incomplete)
+    }
+
+    fn detect_format(&self, text: &str) -> bool {
+        // Reuse the legacy heuristics for now; this will be replaced with Harmony-specific
+        // start-token detection when the parser is fully implemented.
+        text.contains("<|channel|>commentary")
+    }
+
+    fn as_token_parser(&self) -> Option<&dyn TokenToolParser> {
+        Some(self)
+    }
+}
+
+#[async_trait]
+impl TokenToolParser for GptOssHarmonyParser {
+    async fn parse_complete_tokens(
+        &self,
+        _tokens: &[u32],
+    ) -> ToolParserResult<(String, Vec<ToolCall>)> {
+        // Placeholder until Harmony integration lands. Returning an empty tool list ensures
+        // that enabling the parser without full implementation results in a no-op rather
+        // than a runtime panic.
+        Ok((String::new(), Vec::new()))
+    }
+
+    async fn parse_incremental_tokens(
+        &self,
+        _tokens: &[u32],
+        _state: &mut ParseState,
+    ) -> ToolParserResult<StreamResult> {
+        Ok(StreamResult::Incomplete)
+    }
+}

sgl-router/src/tool_parser/parsers/mod.rs

@@ -5,6 +5,7 @@
 // Individual parser modules
 pub mod deepseek_parser;
 pub mod glm4_moe_parser;
+pub mod gpt_oss_harmony_parser;
 pub mod gpt_oss_parser;
 pub mod json_parser;
 pub mod kimik2_parser;
@@ -17,6 +18,7 @@ pub mod step3_parser;
 // Re-export parser types for convenience
 pub use deepseek_parser::DeepSeekParser;
 pub use glm4_moe_parser::Glm4MoeParser;
+pub use gpt_oss_harmony_parser::GptOssHarmonyParser;
 pub use gpt_oss_parser::GptOssParser;
 pub use json_parser::JsonParser;
 pub use kimik2_parser::KimiK2Parser;