Use python3 as the canonical command name course-wide (#104) (#105)

modules/12-revert-reset-and-recovery/README.md

@@ -295,9 +295,9 @@ that *you* hold the judgment: which undo, which parent, whether it actually work
 4. **Now feel the bug.** It passes the first skim:
 
    ```bash
-   python cli.py add "ship it"
-   python cli.py clear          # prints "cleared all tasks", looks fine!
-   python cli.py list           # CRASHES: it corrupted tasks.json, load() blows up
+   python3 cli.py add "ship it"
+   python3 cli.py clear          # prints "cleared all tasks", looks fine!
+   python3 cli.py list           # CRASHES: it corrupted tasks.json, load() blows up
    ```
 
    This is the AI plausibility trap made concrete: the change reviewed fine and "worked," and broke
@@ -337,8 +337,8 @@ that *you* hold the judgment: which undo, which parent, whether it actually work
 
    ```bash
    rm -f tasks.json                              # drop the corrupted state file the bug wrote
-   python cli.py add "back to normal"
-   python cli.py list                            # works again, the clear command is gone
+   python3 cli.py add "back to normal"
+   python3 cli.py list                            # works again, the clear command is gone
    git log --oneline                             # the bad merge is STILL there, with a revert after it
    ```
 
@@ -360,7 +360,7 @@ that *you* hold the judgment: which undo, which parent, whether it actually work
 
    ```bash
    git log --oneline -1         # "Add version command"
-   python cli.py version        # prints the version
+   python3 cli.py version        # prints the version
    ```
 
 2. Now destroy it the way an over-eager "clean up the history" cleanup (or an agent) would, with a
@@ -369,7 +369,7 @@ that *you* hold the judgment: which undo, which parent, whether it actually work
    ```bash
    git reset --hard HEAD~1
    git log --oneline -2         # the "Add version command" commit is GONE from the branch
-   python cli.py version 2>/dev/null || echo "command no longer exists"
+   python3 cli.py version 2>/dev/null || echo "command no longer exists"
    ```
 
    It's not in `log`. It feels permanently lost. It isn't.
@@ -384,7 +384,7 @@ that *you* hold the judgment: which undo, which parent, whether it actually work
 
    ```bash
    git log --oneline -1         # "Add version command" is back
-   python cli.py version        # works again
+   python3 cli.py version        # works again
    ```
 
    You just recovered a commit that `log` swore was gone. Note the honest limit: step 2's `--hard`

modules/12-revert-reset-and-recovery/lab/start/README.md

@@ -15,11 +15,11 @@ This is the running example for **Module 1** (where you feel the copy-paste prob
 ## Run it
 
 ```bash
-python cli.py add "read module 1"
-python cli.py add "set up my editor"
-python cli.py list
-python cli.py done 0
-python cli.py list
+python3 cli.py add "read module 1"
+python3 cli.py add "set up my editor"
+python3 cli.py list
+python3 cli.py done 0
+python3 cli.py list
 ```
 
 Requires Python 3.10+ (it uses `list[Task]` style type hints). No third-party packages.

modules/12-revert-reset-and-recovery/lab/start/cli.py

@@ -1,8 +1,8 @@
 """Tiny command-line front end for the demo task app.
 
 Run it:
-    python cli.py add "write the lesson"
-    python cli.py list
+    python3 cli.py add "write the lesson"
+    python3 cli.py list
 
 State is kept in tasks.json next to this file. It's intentionally minimal; the point of this app
 is to be a realistic-but-small thing you change with an AI, not a product.
@@ -31,7 +31,7 @@ def save(tlist: TaskList) -> None:
 def main(argv: list[str]) -> int:
     tlist = load()
     if not argv:
-        print("usage: python cli.py [add <title> | list | done <index> | count | delete <index>]")
+        print("usage: python3 cli.py [add <title> | list | done <index> | count | delete <index>]")
         return 1
 
     command = argv[0]