diff --git a/scripts/src/hwlab-node-web-observe-runner-source.ts b/scripts/src/hwlab-node-web-observe-runner-source.ts
index fd5d7144..89f2c638 100644
--- a/scripts/src/hwlab-node-web-observe-runner-source.ts
+++ b/scripts/src/hwlab-node-web-observe-runner-source.ts
@@ -2059,14 +2059,16 @@ const analysisDir = path.join(stateDir, "analysis");
 const reportJsonPath = path.join(analysisDir, "report.json");
 const reportMdPath = path.join(analysisDir, "report.md");
 const jsonlReadIssues = [];
-const sourceSamples = await readJsonl(dataFile("samples.jsonl"), { compact: compactSampleForAnalysis });
-const samples = analyzeTailSamples > 0 ? sourceSamples.slice(-analyzeTailSamples) : sourceSamples;
+const sourceSamples = await readJsonl(dataFile("samples.jsonl"), { compact: compactSampleForAnalysis, tail: analyzeTailSamples });
+const samples = sourceSamples;
 const sampleWindow = sampleTimeWindow(samples, 60_000);
-const control = filterRowsByTimeWindow(await readJsonl(dataFile("control.jsonl")), sampleWindow);
-const network = filterRowsByTimeWindow(await readJsonl(dataFile("network.jsonl")), sampleWindow);
-const consoleEvents = filterRowsByTimeWindow(await readJsonl(dataFile("console.jsonl")), sampleWindow);
-const errors = filterRowsByTimeWindow(await readJsonl(dataFile("errors.jsonl")), sampleWindow);
-const artifacts = filterRowsByTimeWindow(await readJsonl(dataFile("artifacts.jsonl")), sampleWindow);
+const relatedJsonlTailLimit = analyzeTailSamples > 0 ? Math.max(1200, analyzeTailSamples * 50) : 0;
+const smallJsonlTailLimit = analyzeTailSamples > 0 ? Math.max(500, analyzeTailSamples * 8) : 0;
+const control = filterRowsByTimeWindow(await readJsonl(dataFile("control.jsonl"), { tail: relatedJsonlTailLimit }), sampleWindow);
+const network = filterRowsByTimeWindow(await readJsonl(dataFile("network.jsonl"), { tail: relatedJsonlTailLimit }), sampleWindow);
+const consoleEvents = filterRowsByTimeWindow(await readJsonl(dataFile("console.jsonl"), { tail: smallJsonlTailLimit }), sampleWindow);
+const errors = filterRowsByTimeWindow(await readJsonl(dataFile("errors.jsonl"), { tail: smallJsonlTailLimit }), sampleWindow);
+const artifacts = filterRowsByTimeWindow(await readJsonl(dataFile("artifacts.jsonl"), { tail: smallJsonlTailLimit }), sampleWindow);
 const manifest = await readJson(path.join(stateDir, "manifest.json"));
 const heartbeat = await readJson(path.join(stateDir, "heartbeat.json"));
 
@@ -2420,6 +2422,8 @@ function parseAlertThresholds(value) {
 }
 
 async function readJsonl(file, options = {}) {
+  const tailLimit = Number.isFinite(Number(options.tail)) && Number(options.tail) > 0 ? Math.floor(Number(options.tail)) : 0;
+  if (tailLimit > 0) return readJsonlTail(file, tailLimit, options);
   const rows = [];
   try {
     const input = createReadStream(file, { encoding: "utf8" });
@@ -2446,6 +2450,72 @@ async function readJsonl(file, options = {}) {
   }
 }
 
+async function readJsonlTail(file, limit, options = {}) {
+  try {
+    const lines = await readTailLines(file, limit);
+    const rows = [];
+    let lineNo = 0;
+    for (const rawLine of lines) {
+      lineNo += 1;
+      const line = String(rawLine || "").trim();
+      if (!line) continue;
+      try {
+        const parsed = JSON.parse(line);
+        rows.push(typeof options.compact === "function" ? options.compact(parsed) : parsed);
+      } catch (error) {
+        const item = { parseError: true, lineNo, tail: true, rawHash: sha256(line), errorMessage: limitText(error && error.message ? error.message : String(error), 240) };
+        rows.push(item);
+        if (jsonlReadIssues.length < 50) jsonlReadIssues.push({ file: path.basename(file), kind: "parse-error", lineNo, tail: true, rawHash: item.rawHash, errorMessage: item.errorMessage });
+      }
+    }
+    return rows;
+  } catch (error) {
+    if (error && error.code === "ENOENT") return [];
+    if (jsonlReadIssues.length < 50) jsonlReadIssues.push({ file: path.basename(file), kind: "read-error", tail: true, code: error && error.code ? String(error.code) : null, errorMessage: limitText(error && error.message ? error.message : String(error), 240) });
+    return [];
+  }
+}
+
+async function readTailLines(file, limit) {
+  const info = await stat(file);
+  if (!info.size || limit <= 0) return [];
+  const chunkSize = 64 * 1024;
+  const maxBytes = 32 * 1024 * 1024;
+  const chunks = [];
+  let position = info.size;
+  let readBytes = 0;
+  let newlineCount = 0;
+  while (position > 0 && newlineCount <= limit && readBytes < maxBytes) {
+    const readSize = Math.min(chunkSize, position, maxBytes - readBytes);
+    position -= readSize;
+    const chunk = await readFileSlice(file, position, readSize);
+    chunks.unshift(chunk);
+    readBytes += chunk.length;
+    for (let index = 0; index < chunk.length; index += 1) {
+      if (chunk[index] === 10) newlineCount += 1;
+    }
+  }
+  if (position > 0 && newlineCount <= limit && jsonlReadIssues.length < 50) {
+    jsonlReadIssues.push({ file: path.basename(file), kind: "tail-scan-truncated", limit, readBytes, fileBytes: info.size });
+  }
+  const text = Buffer.concat(chunks).toString("utf8");
+  let lines = text.split(/\r?\n/u);
+  if (lines.length > 0 && lines[lines.length - 1] === "") lines.pop();
+  if (position > 0 && lines.length > 0) lines.shift();
+  return lines.slice(-limit);
+}
+
+async function readFileSlice(file, start, length) {
+  const chunks = [];
+  await new Promise((resolve, reject) => {
+    const stream = createReadStream(file, { start, end: start + length - 1 });
+    stream.on("data", (chunk) => chunks.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)));
+    stream.on("error", reject);
+    stream.on("end", resolve);
+  });
+  return Buffer.concat(chunks);
+}
+
 function sampleTimeWindow(samples, paddingMs) {
   const times = samples
     .map((item) => Date.parse(String(item && item.ts || "")))