feat: Rust port of Claude Code CLI

Crates:
- api: Anthropic Messages API client with SSE streaming
- tools: Claude-compatible tool implementations (Bash, Read, Write, Edit, Glob, Grep + extended suite)
- runtime: conversation loop, session persistence, permissions, system prompt builder
- rusty-claude-cli: terminal UI with markdown rendering, syntax highlighting, spinners
- commands: subcommand definitions
- compat-harness: upstream TS parity verification

All crates pass cargo fmt/clippy/test.

rust/crates/api/src/sse.rs

@@ -0,0 +1,203 @@
+use crate::error::ApiError;
+use crate::types::StreamEvent;
+
+#[derive(Debug, Default)]
+pub struct SseParser {
+    buffer: Vec<u8>,
+}
+
+impl SseParser {
+    #[must_use]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn push(&mut self, chunk: &[u8]) -> Result<Vec<StreamEvent>, ApiError> {
+        self.buffer.extend_from_slice(chunk);
+        let mut events = Vec::new();
+
+        while let Some(frame) = self.next_frame() {
+            if let Some(event) = parse_frame(&frame)? {
+                events.push(event);
+            }
+        }
+
+        Ok(events)
+    }
+
+    pub fn finish(&mut self) -> Result<Vec<StreamEvent>, ApiError> {
+        if self.buffer.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let trailing = std::mem::take(&mut self.buffer);
+        match parse_frame(&String::from_utf8_lossy(&trailing))? {
+            Some(event) => Ok(vec![event]),
+            None => Ok(Vec::new()),
+        }
+    }
+
+    fn next_frame(&mut self) -> Option<String> {
+        let separator = self
+            .buffer
+            .windows(2)
+            .position(|window| window == b"\n\n")
+            .map(|position| (position, 2))
+            .or_else(|| {
+                self.buffer
+                    .windows(4)
+                    .position(|window| window == b"\r\n\r\n")
+                    .map(|position| (position, 4))
+            })?;
+
+        let (position, separator_len) = separator;
+        let frame = self
+            .buffer
+            .drain(..position + separator_len)
+            .collect::<Vec<_>>();
+        let frame_len = frame.len().saturating_sub(separator_len);
+        Some(String::from_utf8_lossy(&frame[..frame_len]).into_owned())
+    }
+}
+
+pub fn parse_frame(frame: &str) -> Result<Option<StreamEvent>, ApiError> {
+    let trimmed = frame.trim();
+    if trimmed.is_empty() {
+        return Ok(None);
+    }
+
+    let mut data_lines = Vec::new();
+    let mut event_name: Option<&str> = None;
+
+    for line in trimmed.lines() {
+        if line.starts_with(':') {
+            continue;
+        }
+        if let Some(name) = line.strip_prefix("event:") {
+            event_name = Some(name.trim());
+            continue;
+        }
+        if let Some(data) = line.strip_prefix("data:") {
+            data_lines.push(data.trim_start());
+        }
+    }
+
+    if matches!(event_name, Some("ping")) {
+        return Ok(None);
+    }
+
+    if data_lines.is_empty() {
+        return Ok(None);
+    }
+
+    let payload = data_lines.join("\n");
+    if payload == "[DONE]" {
+        return Ok(None);
+    }
+
+    serde_json::from_str::<StreamEvent>(&payload)
+        .map(Some)
+        .map_err(ApiError::from)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse_frame, SseParser};
+    use crate::types::{ContentBlockDelta, OutputContentBlock, StreamEvent};
+
+    #[test]
+    fn parses_single_frame() {
+        let frame = concat!(
+            "event: content_block_start\n",
+            "data: {\"type\":\"content_block_start\",\"index\":0,\"content_block\":{\"type\":\"text\",\"text\":\"Hi\"}}\n\n"
+        );
+
+        let event = parse_frame(frame).expect("frame should parse");
+        assert_eq!(
+            event,
+            Some(StreamEvent::ContentBlockStart(
+                crate::types::ContentBlockStartEvent {
+                    index: 0,
+                    content_block: OutputContentBlock::Text {
+                        text: "Hi".to_string(),
+                    },
+                },
+            ))
+        );
+    }
+
+    #[test]
+    fn parses_chunked_stream() {
+        let mut parser = SseParser::new();
+        let first = b"event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"Hel";
+        let second = b"lo\"}}\n\n";
+
+        assert!(parser
+            .push(first)
+            .expect("first chunk should buffer")
+            .is_empty());
+        let events = parser.push(second).expect("second chunk should parse");
+
+        assert_eq!(
+            events,
+            vec![StreamEvent::ContentBlockDelta(
+                crate::types::ContentBlockDeltaEvent {
+                    index: 0,
+                    delta: ContentBlockDelta::TextDelta {
+                        text: "Hello".to_string(),
+                    },
+                }
+            )]
+        );
+    }
+
+    #[test]
+    fn ignores_ping_and_done() {
+        let mut parser = SseParser::new();
+        let payload = concat!(
+            ": keepalive\n",
+            "event: ping\n",
+            "data: {\"type\":\"ping\"}\n\n",
+            "event: message_stop\n",
+            "data: {\"type\":\"message_stop\"}\n\n",
+            "data: [DONE]\n\n"
+        );
+
+        let events = parser
+            .push(payload.as_bytes())
+            .expect("parser should succeed");
+        assert_eq!(
+            events,
+            vec![StreamEvent::MessageStop(crate::types::MessageStopEvent {})]
+        );
+    }
+
+    #[test]
+    fn ignores_data_less_event_frames() {
+        let frame = "event: ping\n\n";
+        let event = parse_frame(frame).expect("frame without data should be ignored");
+        assert_eq!(event, None);
+    }
+
+    #[test]
+    fn parses_split_json_across_data_lines() {
+        let frame = concat!(
+            "event: content_block_delta\n",
+            "data: {\"type\":\"content_block_delta\",\"index\":0,\n",
+            "data: \"delta\":{\"type\":\"text_delta\",\"text\":\"Hello\"}}\n\n"
+        );
+
+        let event = parse_frame(frame).expect("frame should parse");
+        assert_eq!(
+            event,
+            Some(StreamEvent::ContentBlockDelta(
+                crate::types::ContentBlockDeltaEvent {
+                    index: 0,
+                    delta: ContentBlockDelta::TextDelta {
+                        text: "Hello".to_string(),
+                    },
+                }
+            ))
+        );
+    }
+}