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Mastering Claude

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Claude Code9 lessons76 min
Terminal window with a command prompt and a four-step loop: read, decide, act, checkClaude Code
Path 4, module 1 of 5

Fundamentals and the agent loop

  1. 01Claude Code and the agent loop8 min

    The agent loop is the cycle in which Claude Code thinks about what action to take, calls a real tool, then observes what the tool produced before deciding what comes next. It does not return a single reply: the loop repeats as many times as needed, until the goal is reached. Every reflection and observation displays as it happens.

  2. 02CLAUDE.md, the project's memory10 min

    CLAUDE.md is a text file at the root of a repository, which Claude Code reads automatically at the start of every session opened on it. Its rules are read as context, with no strict guarantee of compliance. To block an action whatever Claude decides, a PreToolUse hook is needed.

  3. 03The essential slash commands8 min

    A few slash commands manage the project's memory, reset the context or summarise it, and inspect what is loaded in the session, without ever touching the repository's code. /clear wipes everything, /compact keeps a summary of what has just been done, useful in the middle of a long task.

  4. 04Permissions and plan mode12 min

    The permission mode decides which actions Claude Code carries out without asking: since September 2026, an interactive terminal or VS Code session with no configured mode starts in auto mode, on every plan, rather than default mode, and auto mode acts broadly under the background watch of a second model.

  5. 05Interrupting and redirecting mid-task7 min

    Esc interrupts the current turn, reflection or tool call, without losing the accumulated context; then type the correction to carry on from the same base. Ctrl+C depends on what is running in the terminal at that moment and, pressed a second time when nothing is running, ends the Claude Code session itself.

  6. 06Pointing to files with @7 min

    The @ symbol, typed in the input field, opens a menu that points to a real file or folder on disk, filters the suggestions as you type, and clearly separates the moment a path is inserted into the message from the moment that message is sent.

  7. 07Running shell commands8 min

    The Bash tool runs a real shell command on your machine, not a simulation, then Claude Code reads the standard output and error output to continue from what was actually produced. A permission prompt appears before every new command, except for a built in set of read only commands.

  8. 08Reading and approving a diff8 min

    A diff is read line by line before being approved: it marks with a minus what disappears from the file and with a plus what is added, and a surgical modification is recognisable by how short these two blocks are. Approval is done through a menu of named options, not a free keystroke.

  9. 09The task list and the status line8 min

    On the most recent models, the task list stays empty by default, with Claude managing multi step work without exposing it, while a status line configured by a script shows the active model, the context window and the session cost live.