diff --git a/next.config.ts b/next.config.ts
index 68a6c64..bee5911 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -1,7 +1,22 @@
+// ABOUTME: Next.js configuration for PhaseFlow application.
+// ABOUTME: Configures standalone output and injects git commit hash for build verification.
+import { execSync } from "node:child_process";
 import type { NextConfig } from "next";
 
+// Get git commit hash at build time for deployment verification
+function getGitCommit(): string {
+  try {
+    return execSync("git rev-parse --short HEAD").toString().trim();
+  } catch {
+    return "unknown";
+  }
+}
+
 const nextConfig: NextConfig = {
   output: "standalone",
+  env: {
+    GIT_COMMIT: process.env.GIT_COMMIT || getGitCommit(),
+  },
 };
 
 export default nextConfig;
diff --git a/src/lib/garmin.ts b/src/lib/garmin.ts
index e779f5c..b7b2ab2 100644
--- a/src/lib/garmin.ts
+++ b/src/lib/garmin.ts
@@ -1,5 +1,7 @@
 // ABOUTME: Garmin Connect API client using stored OAuth tokens.
 // ABOUTME: Fetches body battery, HRV, and intensity minutes from Garmin.
+
+import { logger } from "@/lib/logger";
 import type { GarminTokens, HrvStatus } from "@/types";
 
 const GARMIN_BASE_URL = "https://connect.garmin.com/modern/proxy";
@@ -63,6 +65,10 @@ export async function fetchHrvStatus(
     });
 
     if (!response.ok) {
+      logger.warn(
+        { status: response.status, endpoint: "hrv-service" },
+        "Garmin HRV API error",
+      );
       return "Unknown";
     }
 
@@ -70,13 +76,23 @@ export async function fetchHrvStatus(
     const status = data?.hrvSummary?.status;
 
     if (status === "BALANCED") {
+      logger.info({ status: "BALANCED" }, "Garmin HRV data received");
       return "Balanced";
     }
     if (status === "UNBALANCED") {
+      logger.info({ status: "UNBALANCED" }, "Garmin HRV data received");
       return "Unbalanced";
     }
+    logger.info(
+      { rawStatus: status, hasData: !!data?.hrvSummary },
+      "Garmin HRV returned unknown status",
+    );
     return "Unknown";
-  } catch {
+  } catch (error) {
+    logger.error(
+      { err: error, endpoint: "hrv-service" },
+      "Garmin HRV fetch failed",
+    );
     return "Unknown";
   }
 }
@@ -97,6 +113,10 @@ export async function fetchBodyBattery(
     );
 
     if (!response.ok) {
+      logger.warn(
+        { status: response.status, endpoint: "bodyBattery" },
+        "Garmin body battery API error",
+      );
       return { current: null, yesterdayLow: null };
     }
 
@@ -108,8 +128,22 @@ export async function fetchBodyBattery(
     const yesterdayStats = data?.bodyBatteryStatList?.[0];
     const yesterdayLow = yesterdayStats?.min ?? null;
 
+    logger.info(
+      {
+        current,
+        yesterdayLow,
+        hasCurrentData: !!currentData,
+        hasYesterdayData: !!yesterdayStats,
+      },
+      "Garmin body battery data received",
+    );
+
     return { current, yesterdayLow };
-  } catch {
+  } catch (error) {
+    logger.error(
+      { err: error, endpoint: "bodyBattery" },
+      "Garmin body battery fetch failed",
+    );
     return { current: null, yesterdayLow: null };
   }
 }
@@ -129,6 +163,10 @@ export async function fetchIntensityMinutes(
     );
 
     if (!response.ok) {
+      logger.warn(
+        { status: response.status, endpoint: "fitnessstats" },
+        "Garmin intensity minutes API error",
+      );
       return 0;
     }
 
@@ -136,14 +174,28 @@ export async function fetchIntensityMinutes(
     const weeklyTotal = data?.weeklyTotal;
 
     if (!weeklyTotal) {
+      logger.info(
+        { hasWeeklyTotal: false },
+        "Garmin intensity minutes: no weekly data",
+      );
       return 0;
     }
 
     const moderate = weeklyTotal.moderateIntensityMinutes ?? 0;
     const vigorous = weeklyTotal.vigorousIntensityMinutes ?? 0;
+    const total = moderate + vigorous;
 
-    return moderate + vigorous;
-  } catch {
+    logger.info(
+      { moderate, vigorous, total },
+      "Garmin intensity minutes data received",
+    );
+
+    return total;
+  } catch (error) {
+    logger.error(
+      { err: error, endpoint: "fitnessstats" },
+      "Garmin intensity minutes fetch failed",
+    );
     return 0;
   }
 }
diff --git a/src/lib/metrics.ts b/src/lib/metrics.ts
index d1a5f4d..aec4b68 100644
--- a/src/lib/metrics.ts
+++ b/src/lib/metrics.ts
@@ -47,3 +47,19 @@ export const activeUsersGauge = new promClient.Gauge({
   help: "Number of users with activity in the last 24 hours",
   registers: [metricsRegistry],
 });
+
+// Build info metric: exposes version and git commit for deployment verification
+const buildInfo = new promClient.Gauge({
+  name: "phaseflow_build_info",
+  help: "Build information with version and git commit",
+  labelNames: ["version", "commit"] as const,
+  registers: [metricsRegistry],
+});
+
+// Set build info at module load (value is always 1, labels contain the info)
+buildInfo
+  .labels({
+    version: process.env.npm_package_version || "unknown",
+    commit: process.env.GIT_COMMIT || "unknown",
+  })
+  .set(1);