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+{
+  "id": "03-commands",
+  "title": "Command mastery",
+  "icon": "⌨",
+  "level": "beginner",
+  "lessons": [
+    {
+      "id": "3.1",
+      "title": "Find any command fast",
+      "objective": "Use help, commands and check to discover what exists before guessing.",
+      "minutes": 7,
+      "commands": [
+        "help",
+        "status"
+      ],
+      "blocks": [
+        {
+          "type": "text",
+          "text": "`help` groups all 344 commands by the module that owns them."
+        },
+        {
+          "type": "cmd",
+          "text": "help"
+        },
+        {
+          "type": "cmd",
+          "text": "help webdav-push"
+        },
+        {
+          "type": "tip",
+          "text": "`check` shows module requirements — the fastest way to explain a command that is listed but not working."
+        }
+      ],
+      "exercise": {
+        "instruction": "Open the help for `webdav-push`.",
+        "accept": [
+          "help webdav-push"
+        ],
+        "check": {
+          "type": "command"
+        },
+        "hint": "Type: help webdav-push"
+      },
+      "quiz": {
+        "q": "Which command shows usage for one command?",
+        "options": [
+          "help <cmd>",
+          "status",
+          "ls"
+        ],
+        "answer": 0
+      },
+      "sources": [
+        "modules/core/module-system.js",
+        "modules/core/module-manager.js"
+      ]
+    },
+    {
+      "id": "3.2",
+      "title": "Pipes, grep, sed, tail",
+      "objective": "Combine commands and understand the two semantics that bite: per-line sed and tail -f deltas.",
+      "minutes": 12,
+      "commands": [
+        "grep",
+        "sed",
+        "tail",
+        "sort",
+        "head"
+      ],
+      "blocks": [
+        {
+          "type": "text",
+          "text": "Pipes feed one command into the next. `grep` filters lines, `sed` substitutes text, `tail` prints the end of a file."
+        },
+        {
+          "type": "cmd",
+          "text": "ls | grep txt"
+        },
+        {
+          "type": "warn",
+          "text": "`sed s/x/y/` substitutes the first match per LINE, not per file. `sed -i` is flagged destructive and needs confirmation."
+        },
+        {
+          "type": "text",
+          "text": "`tail -f` is interactive and stops with Ctrl+C. AI-initiated commands get a bounded read instead."
+        },
+        {
+          "type": "cmd",
+          "text": "tail hello.txt"
+        }
+      ],
+      "exercise": {
+        "instruction": "Search the current listing for `txt`.",
+        "accept": [
+          "ls | grep txt",
+          "grep txt"
+        ],
+        "check": {
+          "type": "command"
+        },
+        "hint": "Type: ls | grep txt"
+      },
+      "quiz": {
+        "q": "`sed s/a/b/` replaces…",
+        "options": [
+          "every match in the file",
+          "the first match on each line",
+          "only the last line"
+        ],
+        "answer": 1
+      },
+      "sources": [
+        "modules/core/module-fs.js",
+        "modules/ext/shell.js",
+        "modules/core/terminal.js"
+      ]
+    }
+  ]
+}
+\ No newline at end of file