diff --git a/openspec/changes/code-review-fix/tasks.md b/openspec/changes/code-review-fix/tasks.md
index 804c891..fbb9a81 100644
--- a/openspec/changes/code-review-fix/tasks.md
+++ b/openspec/changes/code-review-fix/tasks.md
@@ -81,7 +81,7 @@
 
 ## 9. Frontend — Shared Types & Type Safety
 
-- [ ] 9.1 `[sonnet]` Create `src/types/candles.ts` with `Candle` interface
+- [x] 9.1 `[sonnet]` Create `src/types/candles.ts` with `Candle` interface
 - [ ] 9.2 `[sonnet]` Create `src/types/annotations.ts` with `Annotation`, `AnnotationType`, `Geometry` interfaces
 - [ ] 9.3 `[sonnet]` Create `src/types/charts.ts` with `Chart` interface
 - [ ] 9.4 `[sonnet]` Create `src/types/predictions.ts` with `PredictionSpan`, `PredictionState`, `ModelInfo` interfaces
diff --git a/src/types/candles.ts b/src/types/candles.ts
new file mode 100644
index 0000000..1889c48
--- /dev/null
+++ b/src/types/candles.ts
@@ -0,0 +1,12 @@
+/**
+ * Candle data types for candlestick chart data
+ */
+
+export interface Candle {
+  time: number;
+  open: number;
+  high: number;
+  low: number;
+  close: number;
+  volume?: number;
+}