Add multilingual language and systems learning tracks

en/expanded-24-2/README.md

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+# Server OS Engineering · 2
+
+[Agila University track](https://edu.agilaos.com/track.php?track=24&lang=en)
+
+About 15 minutes per lesson. Predict, run, change, explain, then complete the check in University.
+
+- [Lesson 1: Durable storage and restore tests](lesson-1/lesson.html)
+- [Lesson 2: Observe latency, errors, and capacity](lesson-2/lesson.html)
+- [Lesson 3: A server-system capstone](lesson-3/lesson.html)

en/expanded-24-2/lesson-1/lesson.html

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+<!doctype html><html lang="en"><meta charset="utf-8"><title>Durable storage and restore tests</title><h1>Durable storage and restore tests</h1><p>15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.</p><p>A backup is useful only if it restores the data and required metadata. Plan consistent database and repository snapshots together. A checksum detects changed bytes; it does not prove a database is logically valid. Define a recovery-point target and recovery-time target. Practice a restore in an isolated environment before an outage.</p><p><strong>Practice and evidence:</strong> Predict the example or draw its state transitions. Change one assumption, test the boundary, and record the actual result. Explain what this small model does not establish about a production system.</p><pre><code class="language-python">import hashlib
+original=b&quot;study record v1&quot;
+restored=bytes(original)
+assert hashlib.sha256(original).digest()==hashlib.sha256(restored).digest()
+print(&quot;Bytes match; application checks still needed&quot;)
+</code></pre><p><strong>Expected result:</strong> <code>Bytes match; application checks still needed</code></p><h3>Practice and evidence</h3><p>Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.</p></html>

en/expanded-24-2/lesson-1/main.py

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+import hashlib
+original=b"study record v1"
+restored=bytes(original)
+assert hashlib.sha256(original).digest()==hashlib.sha256(restored).digest()
+print("Bytes match; application checks still needed")

en/expanded-24-2/lesson-2/lesson.html

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+<!doctype html><html lang="en"><meta charset="utf-8"><title>Observe latency, errors, and capacity</title><h1>Observe latency, errors, and capacity</h1><p>15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.</p><p>Averages hide slow requests. Record a latency distribution, error count, resource use, and the measurement window. Avoid logging passwords or private payloads. The sample computes a median from fixed demonstration data; it is not a measurement of the server. Replace the data with a bounded local experiment and label its environment.</p><p><strong>Practice and evidence:</strong> Predict the example or draw its state transitions. Change one assumption, test the boundary, and record the actual result. Explain what this small model does not establish about a production system.</p><pre><code class="language-python">from statistics import median
+samples_ms=[2,3,3,4,40]
+print(median(samples_ms))
+print(max(samples_ms))
+</code></pre><p><strong>Expected result:</strong> <code>3
+40</code></p><h3>Practice and evidence</h3><p>Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.</p></html>

en/expanded-24-2/lesson-2/main.py

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+from statistics import median
+samples_ms=[2,3,3,4,40]
+print(median(samples_ms))
+print(max(samples_ms))

en/expanded-24-2/lesson-3/lesson.html

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+<!doctype html><html lang="en"><meta charset="utf-8"><title>A server-system capstone</title><h1>A server-system capstone</h1><p>15-minute session: read for 3 minutes, trace for 3, experiment for 7, and complete the check for 2. Spend longer whenever you need.</p><p>Design a reproducible server image in a disposable VM: documented base, service user, firewall, HTTPS, update policy, backup, health check, and restore drill. Record a clean install and a controlled service failure. For an Agila-native server, list missing kernel and driver prerequisites instead of claiming a host application is a new OS. Publish source and a redacted evidence report on Forge.</p><p><strong>Practice and evidence:</strong> Predict the example or draw its state transitions. Change one assumption, test the boundary, and record the actual result. Explain what this small model does not establish about a production system.</p><h3>Practice and evidence</h3><p>Keep three notes: your prediction, the actual result, and why they match or differ. The completion check grades understanding; the practice task builds skill.</p></html>