4 files changed, 221 insertions, 0 deletions
diff --git a/web/frontend/climb-attempts-logic.test.ts b/web/frontend/climb-attempts-logic.test.ts
new file mode 100644
index 0000000..6ce7353
--- /dev/null
+++ b/web/frontend/climb-attempts-logic.test.ts
@@ -0,0 +1,35 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+import { attemptsDomain, formatAttemptDuration, formatPower } from "./climb-attempts-logic.ts";
+import type { ClimbAttemptPoint } from "./types.js";
+
+const makePoint = (durationS: number, averagePowerW: number): ClimbAttemptPoint => ({
+  durationS,
+  averagePowerW,
+  date: "01 Sep 2026, 10:00",
+  rideName: "ride",
+  url: "/rides/1",
+});
+
+test("formats attempt durations as mm:ss and h:mm:ss", () => {
+  assert.equal(formatAttemptDuration(0), "0:00");
+  assert.equal(formatAttemptDuration(1110), "18:30");
+  assert.equal(formatAttemptDuration(3723), "1:02:03");
+  assert.equal(formatAttemptDuration(-5), "0:00");
+});
+
+test("formats power in whole watts", () => {
+  assert.equal(formatPower(235.5), "236 W");
+  assert.equal(formatPower(200), "200 W");
+});
+
+test("pads zero-based axis domains above the data", () => {
+  const domain = attemptsDomain([makePoint(100, 250), makePoint(200, 150)]);
+  assert.equal(domain.maxDurationS, 216);
+  assert.equal(domain.maxPowerW, 270);
+});
+
+test("keeps a drawable domain when data is empty or zero", () => {
+  assert.deepEqual(attemptsDomain([]), { maxDurationS: 1, maxPowerW: 1 });
+  assert.deepEqual(attemptsDomain([makePoint(0, 0)]), { maxDurationS: 1, maxPowerW: 1 });
+});
diff --git a/web/frontend/climb-attempts-logic.ts b/web/frontend/climb-attempts-logic.ts
new file mode 100644
index 0000000..868545b
--- /dev/null
+++ b/web/frontend/climb-attempts-logic.ts
@@ -0,0 +1,30 @@
+import type { ClimbAttemptPoint } from "./types.js";
+
+// formatAttemptDuration renders an attempt duration as "mm:ss", or "h:mm:ss" past an hour.
+export const formatAttemptDuration = (durationS: number): string => {
+  const total = Math.max(0, Math.round(durationS));
+  const seconds = total % 60;
+  const minutes = Math.floor(total / 60) % 60;
+  const hours = Math.floor(total / 3600);
+  const two = (value: number): string => String(value).padStart(2, "0");
+  return hours > 0 ? `${hours}:${two(minutes)}:${two(seconds)}` : `${minutes}:${two(seconds)}`;
+};
+
+// formatPower renders an average power in whole watts.
+export const formatPower = (powerW: number): string => `${Math.round(powerW)} W`;
+
+export interface AttemptsDomain {
+  maxDurationS: number;
+  maxPowerW: number;
+}
+
+// attemptsDomain returns zero-based axis bounds padded above the data; empty or degenerate data still yields a drawable unit domain.
+export const attemptsDomain = (points: ClimbAttemptPoint[]): AttemptsDomain => {
+  let maxDurationS = 0;
+  let maxPowerW = 0;
+  for (const point of points) {
+    maxDurationS = Math.max(maxDurationS, point.durationS);
+    maxPowerW = Math.max(maxPowerW, point.averagePowerW);
+  }
+  return { maxDurationS: maxDurationS * 1.08 || 1, maxPowerW: maxPowerW * 1.08 || 1 };
+};
diff --git a/web/frontend/climb-attempts.ts b/web/frontend/climb-attempts.ts
new file mode 100644
index 0000000..e29dffc
--- /dev/null
+++ b/web/frontend/climb-attempts.ts
@@ -0,0 +1,148 @@
+import { ticks } from "./analytics-logic.js";
+import { attemptsDomain, formatAttemptDuration, formatPower } from "./climb-attempts-logic.js";
+import { resolveOfficialProfileColors } from "./official-climb-profile.js";
+import type { ClimbAttemptPoint, OfficialProfileColors } from "./types.js";
+
+interface Plot {
+  left: number;
+  right: number;
+  top: number;
+  bottom: number;
+}
+
+interface AttemptsChartState {
+  canvas: HTMLCanvasElement;
+  points: ClimbAttemptPoint[];
+  colors: OfficialProfileColors;
+  output: HTMLOutputElement;
+  hoveredIndex: number;
+}
+
+const POINT_RADIUS = 4;
+const HOVER_RADIUS = 7;
+const HIT_RADIUS = 12;
+
+const draw = (state: AttemptsChartState): void => {
+  const { canvas, points, colors } = state;
+  const rect = canvas.getBoundingClientRect();
+  if (rect.width === 0 || rect.height === 0) return;
+  const context = canvas.getContext("2d");
+  if (!context) return;
+  const ratio = window.devicePixelRatio || 1;
+  canvas.width = Math.floor(rect.width * ratio);
+  canvas.height = Math.floor(rect.height * ratio);
+  context.setTransform(ratio, 0, 0, ratio, 0, 0);
+  const plot: Plot = { left: 44, right: rect.width - 16, top: 16, bottom: rect.height - 30 };
+  const domain = attemptsDomain(points);
+  const xForDuration = (durationS: number): number => plot.left + (durationS / domain.maxDurationS) * (plot.right - plot.left);
+  const yForPower = (powerW: number): number => plot.bottom - (powerW / domain.maxPowerW) * (plot.bottom - plot.top);
+  context.clearRect(0, 0, rect.width, rect.height);
+  context.fillStyle = colors.plotSurface;
+  context.fillRect(0, 0, rect.width, rect.height);
+  context.font = "11px system-ui, sans-serif";
+  context.lineWidth = 1;
+  // Duration ticks step in minutes so labels stay round.
+  for (const tick of ticks(0, domain.maxDurationS / 60)) {
+    const x = xForDuration(tick * 60);
+    context.strokeStyle = colors.grid;
+    context.beginPath();
+    context.moveTo(x, plot.top);
+    context.lineTo(x, plot.bottom);
+    context.stroke();
+    context.fillStyle = colors.subtle;
+    context.textAlign = "center";
+    context.textBaseline = "top";
+    context.fillText(formatAttemptDuration(tick * 60), x, plot.bottom + 8);
+  }
+  for (const tick of ticks(0, domain.maxPowerW)) {
+    const y = yForPower(tick);
+    context.strokeStyle = colors.grid;
+    context.beginPath();
+    context.moveTo(plot.left, y);
+    context.lineTo(plot.right, y);
+    context.stroke();
+    context.fillStyle = colors.subtle;
+    context.textAlign = "right";
+    context.textBaseline = "middle";
+    context.fillText(formatPower(tick), plot.left - 8, y);
+  }
+  for (let index = 0; index < points.length; index++) {
+    const point = points[index];
+    context.fillStyle = colors.accent;
+    context.beginPath();
+    context.arc(xForDuration(point.durationS), yForPower(point.averagePowerW), POINT_RADIUS, 0, 2 * Math.PI);
+    context.fill();
+    if (index === state.hoveredIndex) {
+      context.strokeStyle = colors.accent;
+      context.lineWidth = 2;
+      context.beginPath();
+      context.arc(xForDuration(point.durationS), yForPower(point.averagePowerW), HOVER_RADIUS, 0, 2 * Math.PI);
+      context.stroke();
+    }
+  }
+};
+
+const nearestPoint = (state: AttemptsChartState, x: number, y: number): number => {
+  const { canvas, points } = state;
+  const rect = canvas.getBoundingClientRect();
+  const plot: Plot = { left: 44, right: rect.width - 16, top: 16, bottom: rect.height - 30 };
+  const domain = attemptsDomain(points);
+  let nearest = -1;
+  let best = Infinity;
+  for (let index = 0; index < points.length; index++) {
+    const point = points[index];
+    const dx = plot.left + (point.durationS / domain.maxDurationS) * (plot.right - plot.left) - x;
+    const dy = plot.bottom - (point.averagePowerW / domain.maxPowerW) * (plot.bottom - plot.top) - y;
+    const distance = Math.hypot(dx, dy);
+    if (distance < best) {
+      best = distance;
+      nearest = index;
+    }
+  }
+  return best <= HIT_RADIUS ? nearest : -1;
+};
+
+const setHovered = (state: AttemptsChartState, index: number): void => {
+  if (index === state.hoveredIndex) return;
+  state.hoveredIndex = index;
+  if (index < 0) {
+    state.output.textContent = "Hover a point to inspect an attempt.";
+  } else {
+    const point = state.points[index];
+    state.output.textContent = `${point.date} · ${point.rideName} · ${formatAttemptDuration(point.durationS)} · ${formatPower(point.averagePowerW)} · click for details`;
+  }
+  draw(state);
+};
+
+const bindEvents = (state: AttemptsChartState): void => {
+  state.canvas.addEventListener("pointermove", (event: PointerEvent) => {
+    const rect = state.canvas.getBoundingClientRect();
+    const index = nearestPoint(state, event.clientX - rect.left, event.clientY - rect.top);
+    state.canvas.style.cursor = index >= 0 ? "pointer" : "default";
+    setHovered(state, index);
+  });
+  state.canvas.addEventListener("pointerleave", () => {
+    state.canvas.style.cursor = "default";
+    setHovered(state, -1);
+  });
+  state.canvas.addEventListener("pointercancel", () => setHovered(state, -1));
+  state.canvas.addEventListener("click", () => {
+    if (state.hoveredIndex < 0) return;
+    window.open(state.points[state.hoveredIndex].url, "_blank", "noopener");
+  });
+};
+
+const init = (): void => {
+  const payloadElement = document.getElementById("climb-attempt-points");
+  const canvas = document.querySelector<HTMLCanvasElement>("[data-climb-attempts-chart]");
+  const output = document.querySelector<HTMLOutputElement>("[data-attempts-hover]");
+  if (!payloadElement || !canvas || !output) return;
+  const points = JSON.parse(payloadElement.textContent ?? "[]") as ClimbAttemptPoint[];
+  if (points.length === 0) return;
+  const state: AttemptsChartState = { canvas, points, colors: resolveOfficialProfileColors(), output, hoveredIndex: -1 };
+  draw(state);
+  bindEvents(state);
+  window.addEventListener("resize", () => draw(state));
+};
+
+init();
diff --git a/web/frontend/types.d.ts b/web/frontend/types.d.ts
index 74e0765..a933d7d 100644
--- a/web/frontend/types.d.ts
+++ b/web/frontend/types.d.ts
@@ -134,6 +134,14 @@ export interface AnalyticsPoint {
   year: number;
 }
 
+export interface ClimbAttemptPoint {
+  durationS: number;
+  averagePowerW: number;
+  date: string;
+  rideName: string;
+  url: string;
+}
+
 export interface RateLimit {
   limit15: number;
   usage15: number;