feat: parse and display rate_limit_event messages from Claude CLI

Closes #155

- Add RateLimitInfo struct and RateLimitEvent variant to ClaudeMessage
- Emit rate-limit OutputEvent with human-readable message in wsl_bridge
- Add rate-limit line type to TerminalLine union and Terminal rendering
- Display rate-limit lines in amber with [rate-limit] prefix
- Add Terminal.test.ts with 28 tests for getLineClass, getLinePrefix,
  formatTime, isToolContentLong, and truncateToolContent

src-tauri/src/types.rs

@@ -63,6 +63,26 @@ pub struct PermissionDenial {
     pub tool_input: serde_json::Value,
 }
 
+/// Rate limit information from a `rate_limit_event` message.
+/// All fields are optional to ensure forward-compatibility as the Claude CLI evolves.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct RateLimitInfo {
+    #[serde(default)]
+    pub requests_limit: Option<u64>,
+    #[serde(default)]
+    pub requests_remaining: Option<u64>,
+    #[serde(default)]
+    pub requests_reset: Option<String>,
+    #[serde(default)]
+    pub tokens_limit: Option<u64>,
+    #[serde(default)]
+    pub tokens_remaining: Option<u64>,
+    #[serde(default)]
+    pub tokens_reset: Option<String>,
+    #[serde(default)]
+    pub retry_after_ms: Option<u64>,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(tag = "type")]
 pub enum ClaudeMessage {
@@ -100,6 +120,11 @@ pub enum ClaudeMessage {
         #[serde(default)]
         usage: Option<UsageInfo>,
     },
+    #[serde(rename = "rate_limit_event")]
+    RateLimitEvent {
+        #[serde(default)]
+        rate_limit_info: RateLimitInfo,
+    },
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -446,4 +471,77 @@ mod tests {
         assert!(serialized.contains("\"input_tokens\":100"));
         assert!(serialized.contains("\"output_tokens\":50"));
     }
+
+    #[test]
+    fn test_rate_limit_info_default() {
+        let info = RateLimitInfo::default();
+        assert!(info.requests_limit.is_none());
+        assert!(info.requests_remaining.is_none());
+        assert!(info.requests_reset.is_none());
+        assert!(info.tokens_limit.is_none());
+        assert!(info.tokens_remaining.is_none());
+        assert!(info.tokens_reset.is_none());
+        assert!(info.retry_after_ms.is_none());
+    }
+
+    #[test]
+    fn test_rate_limit_event_deserialization_empty_info() {
+        let json = r#"{"type":"rate_limit_event","rate_limit_info":{}}"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        assert!(matches!(msg, ClaudeMessage::RateLimitEvent { .. }));
+    }
+
+    #[test]
+    fn test_rate_limit_event_deserialization_no_info() {
+        // rate_limit_info field is optional via #[serde(default)]
+        let json = r#"{"type":"rate_limit_event"}"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        assert!(matches!(msg, ClaudeMessage::RateLimitEvent { .. }));
+    }
+
+    #[test]
+    fn test_rate_limit_event_deserialization_with_data() {
+        let json = r#"{
+            "type": "rate_limit_event",
+            "rate_limit_info": {
+                "requests_limit": 1000,
+                "requests_remaining": 0,
+                "requests_reset": "2024-01-01T00:01:00Z",
+                "tokens_limit": 50000,
+                "tokens_remaining": 0,
+                "tokens_reset": "2024-01-01T00:01:00Z",
+                "retry_after_ms": 60000
+            }
+        }"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        if let ClaudeMessage::RateLimitEvent { rate_limit_info } = msg {
+            assert_eq!(rate_limit_info.requests_limit, Some(1000));
+            assert_eq!(rate_limit_info.requests_remaining, Some(0));
+            assert_eq!(
+                rate_limit_info.requests_reset,
+                Some("2024-01-01T00:01:00Z".to_string())
+            );
+            assert_eq!(rate_limit_info.retry_after_ms, Some(60000));
+        } else {
+            panic!("Expected RateLimitEvent variant");
+        }
+    }
+
+    #[test]
+    fn test_rate_limit_event_ignores_unknown_fields() {
+        // Ensures forward-compat: unknown fields in rate_limit_info are silently ignored
+        let json = r#"{
+            "type": "rate_limit_event",
+            "rate_limit_info": {
+                "requests_remaining": 0,
+                "some_future_field": "some_value"
+            }
+        }"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        if let ClaudeMessage::RateLimitEvent { rate_limit_info } = msg {
+            assert_eq!(rate_limit_info.requests_remaining, Some(0));
+        } else {
+            panic!("Expected RateLimitEvent variant");
+        }
+    }
 }

src-tauri/src/wsl_bridge.rs

@@ -1521,6 +1521,23 @@ fn process_json_line(
             emit_state_change(app, state, None, conversation_id.clone());
         }
 
+        ClaudeMessage::RateLimitEvent { rate_limit_info } => {
+            tracing::warn!("Rate limit event received: {:?}", rate_limit_info);
+
+            let content = format_rate_limit_message(rate_limit_info);
+            let _ = app.emit(
+                "claude:output",
+                OutputEvent {
+                    line_type: "rate-limit".to_string(),
+                    content,
+                    tool_name: None,
+                    conversation_id: conversation_id.clone(),
+                    cost: None,
+                    parent_tool_use_id: None,
+                },
+            );
+        }
+
         ClaudeMessage::User { message } => {
             // Increment message count for user messages
             stats.write().increment_messages();
@@ -1629,6 +1646,35 @@ fn get_tool_state(tool_name: &str) -> CharacterState {
     }
 }
 
+fn format_rate_limit_message(info: &crate::types::RateLimitInfo) -> String {
+    let mut parts = Vec::new();
+
+    if let (Some(remaining), Some(limit)) = (info.requests_remaining, info.requests_limit) {
+        parts.push(format!("requests: {}/{}", remaining, limit));
+    }
+
+    if let (Some(remaining), Some(limit)) = (info.tokens_remaining, info.tokens_limit) {
+        parts.push(format!("tokens: {}/{}", remaining, limit));
+    }
+
+    if let Some(reset) = &info.requests_reset {
+        parts.push(format!("resets at {}", reset));
+    } else if let Some(reset) = &info.tokens_reset {
+        parts.push(format!("resets at {}", reset));
+    }
+
+    if let Some(retry_ms) = info.retry_after_ms {
+        let secs = retry_ms / 1000;
+        parts.push(format!("retry after {}s", secs));
+    }
+
+    if parts.is_empty() {
+        "Rate limit reached".to_string()
+    } else {
+        format!("Rate limit reached — {}", parts.join(", "))
+    }
+}
+
 fn format_tool_description(name: &str, input: &serde_json::Value) -> String {
     // Helper function to check if a path is a memory file
     fn is_memory_path(path: &str) -> bool {

src/lib/components/Terminal.svelte

@@ -93,6 +93,8 @@
         return "terminal-error";
       case "thinking":
         return "terminal-thinking";
+      case "rate-limit":
+        return "terminal-rate-limit";
       default:
         return "terminal-default";
     }
@@ -110,6 +112,8 @@
         return "[tool]";
       case "error":
         return "[error]";
+      case "rate-limit":
+        return "[rate-limit]";
       default:
         return "";
     }
@@ -362,6 +366,10 @@
     color: var(--terminal-error, #f87171);
   }
 
+  .terminal-rate-limit {
+    color: var(--terminal-rate-limit, #fb923c);
+  }
+
   .terminal-default {
     color: var(--text-primary);
   }

src/lib/components/Terminal.test.ts

@@ -0,0 +1,230 @@
+/**
+ * Terminal Component Tests
+ *
+ * Tests the pure helper functions extracted from the Terminal component:
+ * - getLineClass: maps line types to CSS class names
+ * - getLinePrefix: maps line types to display prefixes
+ * - formatTime: formats a Date as "HH:MM AM/PM"
+ * - isToolContentLong: checks if tool content exceeds collapse threshold
+ * - truncateToolContent: truncates long tool content with ellipsis
+ *
+ * Manual testing checklist:
+ * - [ ] rate-limit lines appear in amber
+ * - [ ] error lines appear in red
+ * - [ ] tool lines appear in purple
+ * - [ ] system lines appear in grey italic
+ * - [ ] user lines appear in cyan
+ * - [ ] assistant lines appear in primary text colour
+ * - [ ] long tool content is collapsed by default with a toggle button
+ */
+
+import { describe, it, expect } from "vitest";
+
+// Mirror functions from Terminal.svelte for isolated testing
+
+function getLineClass(type: string): string {
+  switch (type) {
+    case "user":
+      return "terminal-user";
+    case "assistant":
+      return "terminal-assistant";
+    case "system":
+      return "terminal-system italic";
+    case "tool":
+      return "terminal-tool";
+    case "error":
+      return "terminal-error";
+    case "thinking":
+      return "terminal-thinking";
+    case "rate-limit":
+      return "terminal-rate-limit";
+    default:
+      return "terminal-default";
+  }
+}
+
+function getLinePrefix(type: string): string {
+  switch (type) {
+    case "user":
+      return ">";
+    case "assistant":
+      return "";
+    case "system":
+      return "[system]";
+    case "tool":
+      return "[tool]";
+    case "error":
+      return "[error]";
+    case "rate-limit":
+      return "[rate-limit]";
+    default:
+      return "";
+  }
+}
+
+function formatTime(date: Date): string {
+  return date.toLocaleTimeString("en-US", {
+    hour: "2-digit",
+    minute: "2-digit",
+  });
+}
+
+const TOOL_COLLAPSE_THRESHOLD = 60;
+
+function isToolContentLong(content: string): boolean {
+  return content.length > TOOL_COLLAPSE_THRESHOLD;
+}
+
+function truncateToolContent(content: string): string {
+  return content.slice(0, TOOL_COLLAPSE_THRESHOLD) + "…";
+}
+
+// ---
+
+describe("getLineClass", () => {
+  it("returns terminal-user for user lines", () => {
+    expect(getLineClass("user")).toBe("terminal-user");
+  });
+
+  it("returns terminal-assistant for assistant lines", () => {
+    expect(getLineClass("assistant")).toBe("terminal-assistant");
+  });
+
+  it("returns terminal-system italic for system lines", () => {
+    expect(getLineClass("system")).toBe("terminal-system italic");
+  });
+
+  it("returns terminal-tool for tool lines", () => {
+    expect(getLineClass("tool")).toBe("terminal-tool");
+  });
+
+  it("returns terminal-error for error lines", () => {
+    expect(getLineClass("error")).toBe("terminal-error");
+  });
+
+  it("returns terminal-thinking for thinking lines", () => {
+    expect(getLineClass("thinking")).toBe("terminal-thinking");
+  });
+
+  it("returns terminal-rate-limit for rate-limit lines", () => {
+    expect(getLineClass("rate-limit")).toBe("terminal-rate-limit");
+  });
+
+  it("returns terminal-default for unknown line types", () => {
+    expect(getLineClass("unknown")).toBe("terminal-default");
+    expect(getLineClass("")).toBe("terminal-default");
+    expect(getLineClass("random-future-type")).toBe("terminal-default");
+  });
+});
+
+describe("getLinePrefix", () => {
+  it("returns > for user lines", () => {
+    expect(getLinePrefix("user")).toBe(">");
+  });
+
+  it("returns empty string for assistant lines", () => {
+    expect(getLinePrefix("assistant")).toBe("");
+  });
+
+  it("returns [system] for system lines", () => {
+    expect(getLinePrefix("system")).toBe("[system]");
+  });
+
+  it("returns [tool] for tool lines", () => {
+    expect(getLinePrefix("tool")).toBe("[tool]");
+  });
+
+  it("returns [error] for error lines", () => {
+    expect(getLinePrefix("error")).toBe("[error]");
+  });
+
+  it("returns [rate-limit] for rate-limit lines", () => {
+    expect(getLinePrefix("rate-limit")).toBe("[rate-limit]");
+  });
+
+  it("returns empty string for thinking lines (no prefix)", () => {
+    expect(getLinePrefix("thinking")).toBe("");
+  });
+
+  it("returns empty string for unknown line types", () => {
+    expect(getLinePrefix("unknown")).toBe("");
+    expect(getLinePrefix("")).toBe("");
+  });
+});
+
+describe("formatTime", () => {
+  it("formats time in 12-hour format with AM/PM", () => {
+    const date = new Date(2026, 1, 7, 14, 35);
+    const formatted = formatTime(date);
+    expect(formatted).toMatch(/\d{2}:\d{2}\s?(AM|PM)/i);
+  });
+
+  it("formats afternoon times correctly", () => {
+    const date = new Date(2026, 1, 7, 14, 35);
+    const formatted = formatTime(date);
+    expect(formatted).toContain("02:35");
+    expect(formatted.toUpperCase()).toContain("PM");
+  });
+
+  it("formats morning times correctly", () => {
+    const date = new Date(2026, 1, 7, 9, 5);
+    const formatted = formatTime(date);
+    expect(formatted).toContain("09:05");
+    expect(formatted.toUpperCase()).toContain("AM");
+  });
+
+  it("formats midnight correctly", () => {
+    const date = new Date(2026, 1, 7, 0, 0);
+    const formatted = formatTime(date);
+    expect(formatted).toContain("12:00");
+    expect(formatted.toUpperCase()).toContain("AM");
+  });
+
+  it("formats noon correctly", () => {
+    const date = new Date(2026, 1, 7, 12, 0);
+    const formatted = formatTime(date);
+    expect(formatted).toContain("12:00");
+    expect(formatted.toUpperCase()).toContain("PM");
+  });
+});
+
+describe("isToolContentLong", () => {
+  it("returns false for content at or below the threshold", () => {
+    const exactThreshold = "x".repeat(TOOL_COLLAPSE_THRESHOLD);
+    expect(isToolContentLong(exactThreshold)).toBe(false);
+  });
+
+  it("returns true for content exceeding the threshold", () => {
+    const overThreshold = "x".repeat(TOOL_COLLAPSE_THRESHOLD + 1);
+    expect(isToolContentLong(overThreshold)).toBe(true);
+  });
+
+  it("returns false for short content", () => {
+    expect(isToolContentLong("short")).toBe(false);
+  });
+
+  it("returns false for empty content", () => {
+    expect(isToolContentLong("")).toBe(false);
+  });
+});
+
+describe("truncateToolContent", () => {
+  it("truncates content to the threshold length with an ellipsis", () => {
+    const long = "x".repeat(100);
+    const result = truncateToolContent(long);
+    expect(result).toBe("x".repeat(TOOL_COLLAPSE_THRESHOLD) + "…");
+  });
+
+  it("keeps content shorter than threshold unchanged (plus ellipsis)", () => {
+    const short = "hello";
+    const result = truncateToolContent(short);
+    expect(result).toBe("hello…");
+  });
+
+  it("uses the unicode ellipsis character (not three dots)", () => {
+    const long = "x".repeat(100);
+    const result = truncateToolContent(long);
+    expect(result.endsWith("…")).toBe(true);
+    expect(result.endsWith("...")).toBe(false);
+  });
+});

src/lib/tauri.ts

@@ -323,7 +323,7 @@ export async function initializeTauriListeners() {
     if (conversation_id) {
       claudeStore.addLineToConversation(
         conversation_id,
-        line_type as "user" | "assistant" | "system" | "tool" | "error" | "thinking",
+        line_type as "user" | "assistant" | "system" | "tool" | "error" | "thinking" | "rate-limit",
         content,
         tool_name || undefined,
         costData,
@@ -332,7 +332,7 @@ export async function initializeTauriListeners() {
     } else {
       // Fallback to active conversation if no conversation_id provided
       claudeStore.addLine(
-        line_type as "user" | "assistant" | "system" | "tool" | "error" | "thinking",
+        line_type as "user" | "assistant" | "system" | "tool" | "error" | "thinking" | "rate-limit",
         content,
         tool_name || undefined,
         costData,

src/lib/types/messages.ts

@@ -1,6 +1,6 @@
 export interface TerminalLine {
   id: string;
-  type: "user" | "assistant" | "system" | "tool" | "error" | "thinking";
+  type: "user" | "assistant" | "system" | "tool" | "error" | "thinking" | "rate-limit";
   content: string;
   timestamp: Date;
   toolName?: string;