CHANGELOG.md

@@ -4,25 +4,6 @@ Notable changes to kubestronaut-sim, newest first. A version is the `VERSION` st
 (year.month.day.n); `./ksim help` and the top bar of the web page show the one you are running.
 Every entry names the commit it came in.
 
-## 2026.10.26.2 — 2026-10-26
-
-Everything below came in `e852419`.
-
-### Added
-
-- **Teach a domain**: a domain's lessons you have not done, back to back in one session without
-  a clock - `./ksim lesson ARCH`, the lobby's *Teach a domain* card, or the *Teach a domain*
-  session in the Start exam dialog (`--all`, or a domain whose lessons are all done, brings every
-  one). Every lesson's host is made before the run starts, so there is no waiting between
-  lessons. A lesson's wrap-up leads to the next, the list at the top of a lesson goes to any lesson
-  of the run, and in a terminal `./ksim lesson next` and `./ksim lesson 4.3` do the same.
-  Finishing the run sends you to the domain's timed drill.
-
-### Changed
-
-- A lesson counts as done the moment its last step is checked, not when you finish it, so
-  terminating a lesson or a run keeps the lessons it completed.
-
 ## 2026.10.26.1 — 2026-10-26
 
 Everything below came in `cf4f5be`.

README.md

@@ -136,8 +136,6 @@ host name such as `ckad0013` only resolves in the desktop's terminal: from your
 ./ksim objectives | next | focus     # the curriculum as a path, one objective at a time against the clock
 ./ksim notes 3.2                     # an objective's notes: what to know, fastest commands, traps, docs
 ./ksim lesson [OBJ]                  # the track's lessons, or start one: a guided lab, no clock (CKA: all 27 · CKAD: 2.1-2.4)
-./ksim lesson ARCH [--all]           # teach a domain: its lessons not done yet (--all: every one), back to back
-./ksim lesson next | lesson 4.3      # in a domain's run: the next lesson, or any lesson of the run
 ./ksim lesson step | check | hint | show [N]   # inside a lesson; ./ksim end finishes it
 ./ksim skip DESIGN | unskip DESIGN   # "I am good with this domain (or objective 2.3)": off the path, and back
 ./ksim drill OBS:3 | next OBS:3      # three tasks of a domain, each from another objective - alone, or added
@@ -160,20 +158,10 @@ untimed part of the simulator — they teach, the drills test — and they write
 history, the statistics or the weak list; a lesson whose every step was checked is marked done on
 its objective (`lesson ✓` in the objective list). Steps count in order. Start one from an
 objective's **Lesson** button, **Lesson first** on the path card, the *Take a lesson* session in the
-Start exam dialog, or `./ksim lesson 2.1`.
-
-**Teach a domain** runs a domain's lessons back to back: the ones you have not done, or every
-one again once they all are (`--all` forces that). It is one session without a clock. Every
-lesson's host is made before it starts, as many at a time as for any session (`KSIM_PARALLEL`),
-so you never wait between lessons. Each lesson's wrap-up leads to the next, the list at the top
-of a lesson goes to any lesson of the run, and a lesson counts as done the moment its last step
-is checked, whether or not the run is finished. Finishing the run sends you to the domain's
-timed drill. Start one from the **Teach a domain** card in the lobby, the *Teach a domain*
-session in the Start exam dialog, or `./ksim lesson ARCH`.
-
-**CKA has a lesson for each of its 27 objectives** (`cka/lessons_*.py`, 135 steps), which also
-cover what a full CKA course teaches under them — checked against the outline of KubeDojo's CKA
-course and written from scratch: projected volumes, volume expansion, snapshots and restores, eviction thresholds, debug containers, kube-proxy's
+Start exam dialog, or `./ksim lesson 2.1`. **CKA has a lesson for each of its 27 objectives**
+(`cka/lessons_*.py`, 135 steps), which also cover what a full CKA course teaches under them —
+checked against the outline of KubeDojo's CKA course and written from scratch: projected volumes,
+volume expansion, snapshots and restores, eviction thresholds, debug containers, kube-proxy's
 rules, encryption at rest, in-place resize, PodDisruptionBudgets, QoS classes, ServiceAccount
 tokens, a real upgrade from v1.36 to v1.37, EndpointSlices, an operator. Tasks 132–147 test those
 topics against the clock. The CKAD pilot

cka/lessons.py

@@ -5,7 +5,6 @@ Lessons write nothing to the history or the scores - only a "lesson done" mark o
 
 ./ksim lesson                 the lessons of this track, and which you have done
 ./ksim lesson 1.1             start the lesson of objective 1.1 (id or key)
-./ksim lesson STOR            a domain's lessons not done yet, back to back; ./ksim lesson next moves on
 ./ksim lesson check           check the step you are on; the next one follows
 ./ksim lesson audit [OBJ..]   prove lessons: every step fails before its commands and passes after
 

ckad/lessons.py

@@ -5,7 +5,6 @@ Lessons write nothing to the history or the scores - only a "lesson done" mark o
 
 ./ksim lesson                 the lessons of this track, and which you have done
 ./ksim lesson 2.1             start the lesson of objective 2.1 (id or key)
-./ksim lesson DEPLOY          the domain's lessons not done yet, back to back; ./ksim lesson next moves on
 ./ksim lesson check           check the step you are on; the next one follows
 ./ksim lesson audit [OBJ..]   prove lessons: every step fails before its commands and passes after
 

ksim

@@ -22,7 +22,7 @@ from collections.abc import Callable
 from datetime import datetime
 from typing import Any
 
-VERSION = "2026.10.26.2"
+VERSION = "2026.10.26.1"
 ROOT = os.path.dirname(os.path.abspath(__file__))
 sys.path.insert(0, ROOT)
 from sim import desktop, envs  # noqa: E402
@@ -930,50 +930,21 @@ def known_task(q, known):
 # sends you to the objective's timed drill. It runs as a session of mode "lesson": no clock, its
 # steps checked one at a time and in order, nothing written to the history or the statistics; a
 # lesson whose every step was checked is stamped done in study-<track>.json.
-# A domain's run (./ksim lesson ARCH) is one such session over the domain's lessons, each on its
-# host, all made before it starts: "at" is the lesson you are on, "steps" holds each one's checks.
 def find_lesson(arg):
     """A lesson by its objective (2.1, or the objective's key) or by its id (9201); None if none fits."""
     o = find_objective(arg)
     return next((l for l in LESSONS if (o and l["objective"] == o["id"]) or str(l["id"]) == str(arg)), None)
 
-def lessons_of(st):
-    """The lessons of a lesson session, in order: one, or a domain's run."""
-    if not st or st.get("mode") != "lesson":
-        return []
-    by_id = {l["id"]: l for l in LESSONS}
-    return [by_id[i] for i in st.get("ids", []) if i in by_id]
-
 def lesson_of(st):
-    """The lesson a session is on, or None."""
-    ls = lessons_of(st)
-    return next((l for l in ls if l["id"] == st.get("at")), ls[0] if ls else None)
+    """The lesson a session is, or None."""
+    if not st or st.get("mode") != "lesson":
+        return None
+    return next((l for l in LESSONS if l["id"] in st.get("ids", [])), None)
 
 def lessons_done():
     """objective id -> when its lesson was first done."""
     return load_progress()["lessons"]
 
-def domain_lessons(d, everything=False):
-    """A domain's lessons in curriculum order: those not done yet - all of them once every one is
-    done, or with `everything`."""
-    ls, done = [l for l in LESSONS if l["domain"] == d], lessons_done()
-    left = [l for l in ls if l["objective"] not in done]
-    return ls if everything or not left else left
-
-def steps_of(st, l):
-    """Step index -> its latest check, for lesson l of the session."""
-    return st.get("steps", {}).get(str(l["id"]), {})
-
-def steps_checked(st, l):
-    return sum(1 for i in range(len(l["steps"])) if steps_of(st, l).get(str(i), {}).get("pass"))
-
-def stamp_lesson(l):
-    """Mark l's objective as having its lesson done, the first time."""
-    prog = load_progress()
-    if l["objective"] not in prog["lessons"]:
-        prog["lessons"][l["objective"]] = datetime.now().isoformat(timespec="minutes")
-        save_progress(prog)
-
 def check_step(l, params, i):
     """Run the check of step i on the lesson's host."""
     try:
@@ -984,14 +955,13 @@ def check_step(l, params, i):
 
 def open_step(st, l):
     """The first step not checked yet, or None when every one is."""
-    done = steps_of(st, l)
+    done = st.get("steps", {})
     return next((i for i in range(len(l["steps"])) if not done.get(str(i), {}).get("pass")), None)
 
 def lesson_check(st, i):
     """Check step i of the lesson in progress and keep the result. Steps count in order - a step
     builds on the one before - so only the first open step or one already done can be checked, and
-    a pass stays a pass when a later step changes what an earlier check looked at. The check that
-    completes a lesson stamps it done, whatever then becomes of the session.
+    a pass stays a pass when a later step changes what an earlier check looked at.
     Returns (result, None) or (None, why not)."""
     l = lesson_of(st)
     if not l or st.get("ended_at"):
@@ -1002,28 +972,12 @@ def lesson_check(st, i):
     if first is not None and i > first:
         return None, f"Do step {first + 1} first: steps count in order."
     r = check_step(l, session_params(st, l), i)
-    steps = st.setdefault("steps", {}).setdefault(str(l["id"]), {})
+    steps = st.setdefault("steps", {})
     if r["pass"] or not steps.get(str(i), {}).get("pass"):
         steps[str(i)] = r
     save_state(st)
-    if open_step(st, l) is None:
-        stamp_lesson(l)
     return r, None
 
-def move_to_lesson(st, l):
-    """Go to lesson l of a domain's run - or, once it has ended, review it. Returns why not, or None."""
-    if l["id"] not in st.get("ids", []):
-        return f"Lesson {l['objective']} is not part of this run."
-    st["at"] = l["id"]
-    save_state(st)
-    return None
-
-def next_lesson(st):
-    """The lesson after the current one in a domain's run, or None."""
-    ls, l = lessons_of(st), lesson_of(st)
-    i = ls.index(l) if l in ls else -1
-    return ls[i + 1] if 0 <= i < len(ls) - 1 else None
-
 def task_state(qid, agg):
     """passed = the latest attempt against the clock was a full pass; failed = it was not;
     new = never attempted."""
@@ -1527,8 +1481,7 @@ def open_sessions_elsewhere():
             pass
     return out
 
-def begin_session(qs, mode, duration, force, log: Callable[..., Any] = _log_msg, hard=False, other_ok=None, objective=None,
-                  domain=None):
+def begin_session(qs, mode, duration, force, log: Callable[..., Any] = _log_msg, hard=False, other_ok=None, objective=None):
     st = load_state()
     if st and not st.get("ended_at") and not force:
         die("A session is already in progress. './ksim end' it first, or add --force.")
@@ -1569,9 +1522,7 @@ def begin_session(qs, mode, duration, force, log: Callable[..., Any] = _log_msg,
           "objective": objective}   # the curriculum objective a drill or a lesson was started for, if any
     lesson = mode == "lesson"
     if lesson:
-        st["steps"] = {}   # lesson id -> step index -> its latest check (a pass sticks)
-        st["at"] = qs[0]["id"]
-        st["domain"] = domain   # the domain a run of lessons teaches (./ksim lesson ARCH), if it is one
+        st["steps"] = {}   # step index -> its latest check (a pass sticks)
     save_state(st)
     log("")
     log(bold("=" * 64))
@@ -1579,9 +1530,7 @@ def begin_session(qs, mode, duration, force, log: Callable[..., Any] = _log_msg,
              + ("no clock: take your time" if lesson else "clock started")))
     log(f"  Hosts   : {hosts[0]}" + (f" .. {len(hosts)} in all" if len(hosts) > 1 else "")
         + f"  (Kubernetes {st['k8s']}, as the real {TRACK_ID.upper()} runs {K8S})")
-    if lesson and domain:
-        log(f"  Lessons : {DOMAINS[domain]} - {', '.join(l['objective'] for l in qs)}, {sum(len(l['steps']) for l in qs)} steps")
-    elif lesson:
+    if lesson:
         log(f"  Lesson  : {objective} {qs[0]['title']} - {len(qs[0]['steps'])} steps")
     else:
         log(f"  Ends    : {datetime.fromtimestamp(st['started_at'] + duration).strftime('%H:%M:%S')}  ({duration // 60} min)")
@@ -1593,26 +1542,23 @@ def begin_session(qs, mode, duration, force, log: Callable[..., Any] = _log_msg,
                                    "the exam in the browser: task pane, remote desktop, clock\n")
         + ("  ./ksim lesson step / check / hint / show, ./ksim end   terminal workflow\n" if lesson else
            "  ./ksim list / show N / grade N / timer / end   terminal workflow\n")
-        + ("  ./ksim lesson next   the run's next lesson;  ./ksim lesson OBJ   any lesson of the run\n" if lesson and domain else "")
-        + f"  {'The lesson runs on' if lesson and not domain else 'Every lesson names its host:' if lesson else 'Every task names its host:'}  ssh {hosts[0]}  from the desktop's terminal, then  sudo -i  when you need root.\n"
+        + f"  {'The lesson runs on' if lesson else 'Every task names its host:'}  ssh {hosts[0]}  from the desktop's terminal, then  sudo -i  when you need root.\n"
         + f"  Files go under {WS_DISPLAY}/ on the host.")
     return st
 
 def finish_lesson(st):
-    """End a lesson session: nothing is graded or recorded in the history; each lesson whose every
-    step was checked is stamped done on its objective (the first time). Returns the lines to show."""
+    """End a lesson: nothing is graded or recorded in the history; a lesson whose every step was
+    checked is stamped done on its objective (the first time). Returns the lines to show."""
+    l = lesson_of(st)
     st["ended_at"] = time.time()
-    d, lines = st.get("domain"), []
-    for l in lessons_of(st):
-        n, done = len(l["steps"]), steps_checked(st, l)
+    n, done = len(l["steps"]), sum(1 for i in range(len(l["steps"])) if st.get("steps", {}).get(str(i), {}).get("pass"))
     if done == n:
-            stamp_lesson(l)
-            lines.append(f"✓ Lesson {l['objective']} done - {n}/{n} steps checked."
-                         + ("" if d else f" Now prove it against the clock: ./ksim drill {l['objective']}"))
+        prog = load_progress()
+        prog["lessons"].setdefault(l["objective"], datetime.now().isoformat(timespec="minutes"))
+        save_progress(prog)
+        lines = [f"✓ Lesson {l['objective']} done - {n}/{n} steps checked. Now prove it against the clock: ./ksim drill {l['objective']}"]
     else:
-            lines.append(f"Lesson {l['objective']} finished with {done}/{n} steps checked - take it again any time: ./ksim lesson {l['objective']}")
-    if d:
-        lines.append(f"Now prove {DOMAINS[d]} against the clock: ./ksim drill {d}")
+        lines = [f"Lesson {l['objective']} finished with {done}/{n} steps checked - take it again any time: ./ksim lesson {l['objective']}"]
     st["milestones"] = lines
     save_state(st)
     return lines
@@ -1741,45 +1687,24 @@ def cli_md(text):
 
 def print_step(l, params, i, st=None):
     s = l["steps"][i]
-    done = bool(st and steps_of(st, l).get(str(i), {}).get("pass"))
+    done = bool(st and st.get("steps", {}).get(str(i), {}).get("pass"))
     print(bold(f"Step {i + 1} of {len(l['steps'])}: {render(s['title'], params, l)}") + (green("   ✓ checked") if done else ""))
     print(cli_md(render(s["text"], params, l)))
     print(dim("  ./ksim lesson check   when it is done        ./ksim lesson hint / show   if you are stuck"))
 
-def print_outro(l, params, st):
+def print_outro(l, params):
     print(bold("Every step is checked.")); print("-" * 64)
     print(cli_md(render(l["outro"], params, l))); print("-" * 64)
-    nxt = next_lesson(st) if st.get("domain") else None
-    if nxt:
-        print(dim(f"  ./ksim lesson next   lesson {nxt['objective']}: {nxt['title']}"))
-    print(dim(f"  ./ksim end   finishes the {'run' if st.get('domain') else 'lesson'}"))
-
-def print_lesson(st, l):
-    """A lesson as you arrive at it: its host, its introduction, then the step you are on."""
-    params, ls, i = session_params(st, l), lessons_of(st), open_step(st, l)
-    where = f"   lesson {ls.index(l) + 1} of {len(ls)} in {DOMAINS[st['domain']]}" if st.get("domain") else ""
-    print(); print(bold(f"Lesson {l['objective']} - {l['title']}") + dim(where)); print("-" * 64)
-    print(f"It runs on:  ssh {host_of(l)}\n")
-    print(cli_md(render(l["intro"], params, l))); print("-" * 64)
-    return print_outro(l, params, st) if i is None else print_step(l, params, i, st)
+    print(dim("  ./ksim end   finishes the lesson"))
 
 def cmd_lesson(args):
     """Lessons (<track>/lessons.py): guided labs on a host of your own, with no clock.
-    ./ksim lesson | lesson OBJ | lesson DOMAIN [--all] | lesson next | lesson step|check|hint|show [N]
-    | lesson audit [OBJ..]"""
+    ./ksim lesson | lesson OBJ | lesson step|check|hint|show [N] | lesson audit [OBJ..]"""
     sub = args[0] if args else ""
     if sub == "audit":
         return lesson_audit(args[1:])
     st = load_state()
     live = lesson_of(st) if st and not st.get("ended_at") else None
-    if sub == "next":
-        if not live or not st.get("domain"):
-            die("No run of lessons in progress.  ./ksim lesson DOMAIN   starts one: a domain's lessons, back to back.")
-        nxt = next_lesson(st)
-        if not nxt:
-            die(f"Lesson {live['objective']} is the last of the run.  ./ksim end   finishes it")
-        move_to_lesson(st, nxt)
-        return print_lesson(st, nxt)
     if sub in ("check", "step", "hint", "show"):
         if not live:
             die("No lesson in progress.  ./ksim lesson   lists them;  ./ksim lesson 2.1   starts one.")
@@ -1787,7 +1712,7 @@ def cmd_lesson(args):
         num = [a for a in args[1:] if a.isdigit()]
         i = int(num[0]) - 1 if num else open_step(st, live)
         if i is None:
-            return print_outro(live, params, st)
+            return print_outro(live, params)
         if not 0 <= i < len(live["steps"]):
             die(f"The lesson has steps 1 to {len(live['steps'])}.")
         s = live["steps"][i]
@@ -1808,37 +1733,28 @@ def cmd_lesson(args):
             print(dim("  ./ksim lesson hint   a hint        ./ksim lesson show   the commands"))
             return
         print(green(f"✓ Step {i + 1} done: {render(s['title'], params, live)}")); print()
-        st = load_state(); nxt = open_step(st, live)
-        return print_outro(live, params, st) if nxt is None else print_step(live, params, nxt)
-    if sub.upper() in DOMAINS:   # a domain's run: its lessons not done yet, every host made up front
-        d = sub.upper(); ls = domain_lessons(d, "--all" in args)
-        if not ls:
-            die(f"{DOMAINS[d]} has no lessons yet.")
-        st = begin_session(ls, "lesson", 0, "--force" in args, domain=d)
-        return print_lesson(st, ls[0])
+        nxt = open_step(load_state(), live)
+        return print_outro(live, params) if nxt is None else print_step(live, params, nxt)
     if sub:
         l = find_lesson(sub)
         if not l:
             die(f"No lesson for '{sub}'. The {TRACK_ID.upper()} lessons: "
                 + (", ".join(f"{x['objective']} ({x['title']})" for x in LESSONS) or "none yet") + "   (./ksim lesson lists them)")
-        if live and st.get("domain") and l["id"] in st["ids"]:   # a lesson of the run in progress: go there
-            move_to_lesson(st, l)
-            return print_lesson(st, l)
         st = begin_session([l], "lesson", 0, "--force" in args, objective=l["objective"])
-        return print_lesson(st, l)
+        params = session_params(st, l)
+        print(); print(bold(f"Lesson {l['objective']} - {l['title']}")); print("-" * 64)
+        print(cli_md(render(l["intro"], params, l))); print("-" * 64)
+        print_step(l, params, 0, st)
+        return
     if not LESSONS:
         print(f"No lessons for {TRACK_ID.upper()} yet.")
         return
-    done, by_domain = lessons_done(), {}
+    done = lessons_done()
     print(bold(f"{TRACK['name']} - lessons") + dim("   guided labs on a host of your own, with no clock"))
     for l in LESSONS:
-        by_domain.setdefault(l["domain"], []).append(l)
-        here = live is not None and l["id"] == live["id"]
-        print(f" {cyan('→') if here else green('✓') if l['objective'] in done else dim('·')} {l['objective']:<5} {l['title']}"
+        print(f" {green('✓') if l['objective'] in done else dim('·')} {l['objective']:<5} {l['title']}"
               + dim(f"   {len(l['steps'])} steps · {DOMAINS.get(l['domain'], l['domain'])}"))
-    runs = ", ".join(f"{d} {sum(x['objective'] in done for x in ls)}/{len(ls)}" for d, ls in by_domain.items())
     print(dim(f"\n  ./ksim lesson {LESSONS[0]['objective']}   starts that lesson      ./ksim lesson audit   proves them on real clusters"))
-    print(dim(f"  ./ksim lesson {LESSONS[0]['domain']}   a domain's lessons not done yet, back to back ({runs} done)"))
 
 def lesson_audit(args):
     """Prove lessons on real clusters: each is seeded on a host of its own; then every step must
@@ -2006,8 +1922,7 @@ def status_line(st):
     l = lesson_of(st)
     if l:
         n = len(l["steps"]); done = n if open_step(st, l) is None else open_step(st, l)
-        ls = lessons_of(st); run = f"{st['domain']} lesson {ls.index(l) + 1}/{len(ls)}: " if st.get("domain") else ""
-        return green("lesson - no clock") + dim(f"  [{run}{l['objective']} {done}/{n} steps checked]")
+        return green("lesson - no clock") + dim(f"  [{done}/{n} steps checked]")
     r = remaining(st)
     if st.get("paused_at"):
         return yellow(f"⏸  PAUSED - {fmt(r)} remaining") + dim("  ./ksim resume")
@@ -2076,8 +1991,7 @@ def cmd_end(args):
     if st.get("mode") == "lesson":   # nothing to grade: the steps were checked as you went
         for line in finish_lesson(st):
             print(green(line) if line.startswith("✓") else line)
-        print(dim("A lesson writes nothing to the history or the scores. " + ("Its hosts stay" if st.get("domain") else "Its host stays")
-                  + " up until the next session."))
+        print(dim("A lesson writes nothing to the history or the scores. Its host stays up until the next session."))
         return
     down = hosts_down(st)
     if down:
@@ -2236,11 +2150,6 @@ class Api(http.server.BaseHTTPRequestHandler):
                             if not l:
                                 die(f"No lesson for {body['lesson']}.")
                             begin_session([l], "lesson", 0, True, log=ulog, other_ok=False, objective=l["objective"])
-                        elif body.get("teach"):   # a domain's run of lessons
-                            d = str(body["teach"]).upper(); ls = domain_lessons(d, bool(body.get("all"))) if d in DOMAINS else []
-                            if not ls:
-                                die(f"No lessons for domain {body['teach']}.")
-                            begin_session(ls, "lesson", 0, True, log=ulog, other_ok=False, domain=d)
                         elif body.get("sim") in SETS:
                             begin_session(set_questions(body["sim"]), "exam", EXAM_SECONDS, True, log=ulog, hard=True, other_ok=False)
                         elif mode == "exam":
@@ -2289,11 +2198,6 @@ class Api(http.server.BaseHTTPRequestHandler):
                 _, why = lesson_check(st, int(body.get("step", -1)))
                 if why:
                     return self._json({"error": why}, 400)
-            elif p.path == "/api/lesson/at":   # another lesson of the run in progress
-                l = find_lesson(str(body.get("lesson", "")))
-                why = move_to_lesson(st, l) if l else "No such lesson."
-                if why:
-                    return self._json({"error": why}, 400)
             elif p.path == "/api/pause":
                 set_paused(st, bool(body.get("paused", True)))
             elif p.path == "/api/restart":
@@ -2360,15 +2264,8 @@ class Api(http.server.BaseHTTPRequestHandler):
                                   "domains": self.domain_scores(st), "server_time": time.time()}
             l = lesson_of(st)
             if l:
-                payload["session"]["steps"] = steps_of(st, l)   # the steps of the lesson you are on
+                payload["session"]["steps"] = st.get("steps", {})
                 payload["lesson"] = self.lesson_payload(l, session_params(st, l))
-                if st.get("domain"):   # a domain's run: every lesson of it, and how far each one is
-                    payload["course"] = {"domain": st["domain"], "name": DOMAINS[st["domain"]], "at": l["id"],
-                                         "lessons": [{"id": x["id"], "objective": x["objective"], "title": x["title"], "host": host_of(x),
-                                                      "steps": [{"title": render(s["title"], session_params(st, x), x).strip(),
-                                                                 "pass": bool(steps_of(st, x).get(str(i), {}).get("pass"))}
-                                                                for i, s in enumerate(x["steps"])]}
-                                                     for x in lessons_of(st)]}
         return payload
 
     def lesson_payload(self, l: dict[str, Any], params: dict[str, Any]) -> dict[str, Any]:
@@ -2683,8 +2580,6 @@ def cmd_help(args):
         "  drill OBJ                an objective's tasks against the clock, those not yet passed first\n")
     objective_help += "" if not LESSONS else (
         f"  lesson [OBJ]             the track's lessons ({len(LESSONS)}), or start one: a guided lab on a host of your own, no clock\n"
-        "  lesson DOMAIN [--all]    teach a domain: its lessons not done yet (--all: every one) back to back, hosts made up front\n"
-        "  lesson next | OBJ        in a domain's run: on to its next lesson, or to any lesson of it\n"
         "  lesson step|check|hint|show [N]   the step you are on, check it, a hint, the commands;  ./ksim end finishes\n"
         "  lesson audit [OBJ..]     prove lessons: every step fails before its commands and passes after them\n")
     print(f"""usage: ./ksim [--track cka|ckad|cks] <command>        (current track: {TRACK_ID}, {len(QUESTIONS)} tasks)

web/index.html

@@ -290,7 +290,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
   .lmark { font: 600 11px var(--sans); text-transform: uppercase; letter-spacing: .04em; padding: 1px 7px; border-radius: 50px;
            border: 1px solid var(--line); color: var(--muted); margin-right: 6px; white-space: nowrap; }
   .lmark.done { border-color: var(--ok-text); color: var(--ok-text); }
-  .qhead select.select { width: auto; max-width: 100%; padding: .15rem .5rem; font-size: 13px; margin-left: 4px; }
   .stepsum { margin: 0 0 14px; color: var(--muted); font-size: 13px; text-transform: uppercase; letter-spacing: .05em; }
   .checkrow { display: flex; gap: 10px; align-items: center; flex-wrap: wrap; margin-top: 16px; font-size: 13px; }
   .checks { margin-top: 14px; background: var(--surface-2); border: 1px solid var(--line); border-radius: 6px; padding: 12px 14px; font-size: 14px; }
@@ -405,11 +404,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
       <div class="ladder" id="ladder"></div>
       <div class="pathgo"><button class="btn btn-primary" id="pathGo">Continue</button><button class="btn btn-success hidden" id="pathLesson">Lesson first</button><span class="why" id="pathWhy"></span></div>
     </section>
-    <section class="card hidden" id="teachCard">
-      <h2 class="section-title">Teach a domain</h2>
-      <p class="section-sub">A domain's lessons you have not done, back to back and with no clock. Every lesson's host is made before you start, and a lesson counts as done the moment its last step is checked.</p>
-      <div class="dpills" id="teachPills"></div>
-    </section>
     <section class="card" id="domainCard">
       <h2 class="section-title">Drill a domain</h2>
       <p class="section-sub">Five tasks of one domain, against the clock. ✓ drilled at least once, » marked known.</p>
@@ -521,7 +515,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
       <div class="field"><label class="lbl" for="pkTrack">Certification</label><select class="select" id="pkTrack"></select></div>
       <div class="field"><label class="lbl" for="pkSession">Session</label><select class="select" id="pkSession"></select></div>
       <div class="field hidden" id="pkLessonRow"><label class="lbl" for="pkLesson">Lesson</label><select class="select" id="pkLesson"></select></div>
-      <div class="field hidden" id="pkTeachRow"><label class="lbl" for="pkTeach">Domain</label><select class="select" id="pkTeach"></select></div>
       <div class="field hidden" id="pkObjRow"><label class="lbl" for="pkObjective">Objective</label><select class="select" id="pkObjective"></select></div>
       <div class="field hidden" id="pkDomRow"><label class="lbl" for="pkDomain">Domain</label><select class="select" id="pkDomain"></select></div>
       <div class="field hidden" id="pkPickRow"><label class="lbl">Tasks</label><div class="picker" id="pkTasks"></div></div>
@@ -689,14 +682,13 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     const ended = sess && sess.ended_at;
     $('#navResults').classList.toggle('hidden', !(ended && !sess.aborted));
     const lessonLine = () => { const n = S.lesson.steps.length, c = Object.values(sess.steps || {}).filter(r => r.pass).length;
-      if (S.course) return `Your last run of lessons, ${esc(S.course.domain)}, ended with ${courseDone()}/${S.course.lessons.length} lessons done. <a href="#" id="lastResults">View its summary</a>`;
       return `Your last lesson, ${esc(S.lesson.objective)}, ended with ${c}/${n} steps checked. <a href="#" id="lastResults">View its summary</a>`; };
     $('#lastLine').innerHTML = !ended ? 'Every task gets its own cluster: a drill is ready in about a minute, a full exam in three or four.'
       : sess.aborted ? 'Your last session was terminated: nothing was graded or recorded.'
       : sess.mode === 'lesson' && S.lesson ? lessonLine()
       : `Your last ${sess.mode === 'drill' ? 'drill' : 'exam'} ended with ${sess.score.pct}%. <a href="#" id="lastResults">View its results</a>`;
     const lr = $('#lastResults'); if (lr) lr.onclick = e => { e.preventDefault(); go('results'); };
-    paintPath(); paintTeach(); paintDomains();
+    paintPath(); paintDomains();
   }
 
   function paintPath() {
@@ -744,23 +736,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     });
   }
 
-  // a domain's lessons, back to back: what each domain has left
-  function teachPlan(d) {
-    const ls = (S.objectives || []).filter(o => o.lesson && o.domain === d), left = ls.filter(o => !o.lesson.done), go = left.length ? left : ls;
-    return {all: ls, left, steps: go.reduce((a, o) => a + o.lesson.steps, 0)};
-  }
-  const teachDomains = () => [...new Set((S.objectives || []).filter(o => o.lesson).map(o => o.domain))];
-  function paintTeach() {
-    const doms = teachDomains();
-    $('#teachCard').classList.toggle('hidden', !doms.length);
-    $('#teachPills').innerHTML = doms.map(d => {
-      const p = teachPlan(d), n = p.all.length;
-      return `<button class="dpill ${p.left.length ? '' : 'done'}" data-teach="${d}" title="./ksim lesson ${d}: ${p.left.length ? 'the lessons you have not done' : 'every lesson again'}, back to back"><b>${d}</b><span class="mk">${n - p.left.length}/${n}</span><span>${esc(S.track.domains[d])}</span>`
-        + `<span>${p.left.length ? `${p.left.length} lesson${p.left.length > 1 ? 's' : ''} to go · ${p.steps} steps` : `all done · take the ${n} again`}</span></button>`;
-    }).join('');
-    $$('#teachPills [data-teach]').forEach(el => el.onclick = () => startTeach(el.dataset.teach));
-  }
-
   function paintDomains() {
     const drilled = S.drilled || {}, skipped = S.known || [];
     $('#coverage').innerHTML = Object.keys(S.track.domains).map(d => {
@@ -790,7 +765,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
   function sessionOptions() {
     const o = [];
     if (S.path) o.push(['path', `Continue the path — ${S.path.next.cmd.replace('./ksim ', '')}`]);
-    if ((S.objectives || []).some(x => x.lesson)) o.push(['lesson', 'Take a lesson — a guided lab, no clock'], ['teach', 'Teach a domain — its lessons back to back, no clock']);
+    if ((S.objectives || []).some(x => x.lesson)) o.push(['lesson', 'Take a lesson — a guided lab, no clock']);
     if ((S.objectives || []).length) o.push(['objective', 'Drill an objective']);
     o.push(['domain', 'Drill a domain'], ['next', `Drill the next domain — ${S.track.domains[nextDomain()]}`],
            ['all', 'Drill the whole bank'], ['pick', 'Pick the tasks to drill']);
@@ -808,9 +783,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     const withLesson = (S.objectives || []).filter(o => o.lesson);
     $('#pkLesson').innerHTML = withLesson.map(o => `<option value="${o.id}">${o.lesson.done ? '✓' : '·'} ${o.id} ${esc(o.lesson.title)}</option>`).join('');
     const firstOpen = withLesson.find(o => !o.lesson.done); if (firstOpen) $('#pkLesson').value = firstOpen.id;
-    $('#pkTeach').innerHTML = teachDomains().map(d => { const p = teachPlan(d);
-      return `<option value="${d}">${d} — ${esc(S.track.domains[d])} · ${p.all.length - p.left.length}/${p.all.length} lessons done</option>`; }).join('');
-    const teachOpen = teachDomains().find(d => teachPlan(d).left.length); if (teachOpen) $('#pkTeach').value = teachOpen;
     $('#pkDomain').innerHTML = Object.entries(S.track.domains).map(([d, n]) => `<option value="${d}">${d} — ${esc(n)}${(S.drilled || {})[d] ? '  ✓' : (S.known || []).includes(d) ? '  »' : ''}</option>`).join('');
     $('#pkTasks').dataset.filled = '';
     $('#hardPicker').checked = hard; $('#pkErr').classList.add('hidden');
@@ -820,7 +792,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     const v = $('#pkSession').value, T = S.track, per = hard ? 5 : 6;
     $('#pkObjRow').classList.toggle('hidden', v !== 'objective');
     $('#pkLessonRow').classList.toggle('hidden', v !== 'lesson');
-    $('#pkTeachRow').classList.toggle('hidden', v !== 'teach');
     $('#pkDomRow').classList.toggle('hidden', v !== 'domain');
     $('#pkPickRow').classList.toggle('hidden', v !== 'pick');
     let desc = '', warn = '';
@@ -829,10 +800,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
       const o = (S.objectives || []).find(x => x.id === $('#pkLesson').value);
       desc = `A guided lab on a host of your own: an introduction, then ${o ? o.lesson.steps : 'a few'} steps, each with a Check button, a hint and the commands. No clock, and nothing goes into your history or scores. It ends by sending you to the objective's timed drill.`;
     }
-    else if (v === 'teach') {
-      const d = $('#pkTeach').value, p = teachPlan(d), k = (p.left.length || p.all.length);
-      desc = `${p.left.length ? `The ${k} lesson${k > 1 ? 's' : ''} of ${S.track.domains[d]} you have not done` : `All ${k} lessons of ${S.track.domains[d]} again`} (${p.steps} steps), one after another. Every lesson has a host of its own, all made before you start, so there is no waiting between them. No clock, nothing goes into your history or scores, and a lesson counts as done the moment its last step is checked. It ends by sending you to the domain's timed drill.`;
-    }
     else if (v === 'objective') desc = `Its tasks that have not passed against the clock yet, up to five in a sitting, ${per} minutes each. Feedback per task while you work; a task's solution once it is graded.`;
     else if (v === 'domain') desc = `Five tasks of that domain, ${per} minutes each, the ones you have seen least recently first. Feedback per task while you work.`;
     else if (v === 'next') desc = `${T.domains[nextDomain()]} — 5 tasks, ${per} min each. Drills rotate through all domains before the exam.`;
@@ -849,7 +816,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     }
     $('#pkDesc').textContent = desc;
     $('#pkWarn').textContent = warn; $('#pkWarn').classList.toggle('hidden', !warn);
-    $('#pkStart').textContent = warn ? 'Start anyway' : v === 'lesson' ? 'Start lesson' : v === 'teach' ? 'Start the lessons' : 'Start exam';
+    $('#pkStart').textContent = warn ? 'Start anyway' : v === 'lesson' ? 'Start lesson' : 'Start exam';
   }
   async function fillTaskPicker() {
     const box = $('#pkTasks'), want = hard ? 'hard' : 'normal';
@@ -864,7 +831,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     const v = $('#pkSession').value;
     if (v === 'path') return continuePath();
     if (v === 'lesson') return startLesson($('#pkLesson').value);
-    if (v === 'teach') return startTeach($('#pkTeach').value);
     if (v === 'objective') return start('drill', null, false, false, null, $('#pkObjective').value);
     if (v === 'domain') return start('drill', null, false, false, $('#pkDomain').value);
     if (v === 'next') return start('drill', null, true);
@@ -901,7 +867,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     launch({mode, ids, next: !!next, campaign: !!campaign, domain: domain || null, objective: objective || null, touch: touch || null, hard});
   const startSim = name => launch({mode: 'exam', sim: name, hard: true});
   const startLesson = obj => launch({lesson: obj});
-  const startTeach = d => launch({teach: d});
   const isLesson = () => !!(S && S.lesson && S.session && S.session.mode === 'lesson');
   async function resumeSeeding() {
     polling = true; openModal('#mPrep');
@@ -913,20 +878,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     skew = Date.now() / 1000 - S.session.server_time; autoSubmitted = false; $('#vnc').dataset.ready = '';
     cur = S.questions[0] && S.questions[0].id; lpage = fresh ? 0 : null; go('exam');
     if (!fresh) return;
-    if (isLesson() && S.course) {   // a domain's run: how it goes
-      const C = S.course, n = C.lessons.length;
-      $('#startTitle').textContent = `${C.name}: ${n} lesson${n > 1 ? 's' : ''}`;
-      $('#startBody').innerHTML = `<div class="alert alert-info"><b>No clock.</b> Take your time: the lessons teach, the drills test.</div>
-        <ul>
-          <li>every lesson has a host of its own, and all ${n} are up already: the top of each lesson says which to <code class="ic">ssh</code> to;</li>
-          <li>a lesson is an introduction, then steps - each with a <b>Check step</b> button, a hint, and the commands if you are stuck; steps count in order;</li>
-          <li>a lesson's wrap-up leads to the next one, and the list at the top goes to any lesson of the run;</li>
-          <li>a lesson counts as done the moment its last step is checked; nothing goes into your history or scores;</li>
-          <li>finish the run from <b>Controls</b>, then drill ${esc(C.domain)} against the clock.</li>
-        </ul>`;
-      openModal('#mStart');
-      return;
-    }
     if (isLesson()) {   // no clock to start: the dialog only says how a lesson goes
       const L = S.lesson;
       $('#startTitle').textContent = `Lesson ${L.objective}: ${L.title}`;
@@ -966,15 +917,14 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
   function paintMenus() {
     const sess = S.session;
     if (isLesson()) {
-      const what = S.course ? 'the run' : 'lesson';
       $('#mnControls').innerHTML = live()
-        ? `<button class="dd-item" data-act="finishLesson">Finish ${what}</button>
+        ? `<button class="dd-item" data-act="finishLesson">Finish lesson</button>
            <div class="dd-sep"></div>
-           <button class="dd-item danger" data-act="terminate">Terminate ${what}</button>`
+           <button class="dd-item danger" data-act="terminate">Terminate lesson</button>`
         : `<button class="dd-item" data-act="results">Back to the summary</button>
            <button class="dd-item" data-act="dashboard">Back to the dashboard</button>
            <div class="dd-sep"></div>
-           <button class="dd-item danger" data-act="terminate">Delete the host${S.course ? 's' : ''}</button>`;
+           <button class="dd-item danger" data-act="terminate">Delete the host</button>`;
       return;
     }
     $('#mnControls').innerHTML = live()
@@ -1051,11 +1001,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     catch (e) { alert(e.message); b.disabled = false; b.textContent = 'Check this task'; }
   }
   function step(d) {
-    if (isLesson()) {
-      const nx = nextLesson();
-      if (d > 0 && lpage === S.lesson.steps.length + 1 && nx) return goLesson(nx.id);
-      lpage = Math.max(0, Math.min(lpage + d, S.lesson.steps.length + 1)); paintExam(); $('#qContent').scrollTop = 0; return;
-    }
+    if (isLesson()) { lpage = Math.max(0, Math.min(lpage + d, S.lesson.steps.length + 1)); paintExam(); $('#qContent').scrollTop = 0; return; }
     const i = S.questions.findIndex(q => q.id === cur), j = i + d;
     if (j >= 0 && j < S.questions.length) { cur = S.questions[j].id; paintExam(); $('#qContent').scrollTop = 0; }
   }
@@ -1067,21 +1013,11 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     const n = S.lesson.steps.length, k = [...Array(n).keys()].find(i => !stepDone(i));
     return k === undefined ? n + 1 : k + 1;
   }
-  // a domain's run: the lessons in it, the one after the current, how many are done
-  const courseIdx = () => S.course ? S.course.lessons.findIndex(x => x.id === S.course.at) : -1;
-  const nextLesson = () => S.course ? S.course.lessons[courseIdx() + 1] || null : null;
-  const courseDone = () => S.course.lessons.filter(x => x.steps.every(s => s.pass)).length;
-  async function goLesson(id) {
-    try { S = await api('/api/lesson/at', {lesson: String(id)}); }
-    catch (e) { alert(e.message === 'not found' ? oldServer('Teach a domain') : e.message); return; }
-    lpage = Object.values(S.session.steps || {}).some(r => r.pass) ? null : 0;   // a lesson not started opens on its introduction
-    paintExam(); $('#qContent').scrollTop = 0;
-  }
   function paintLesson() {
-    const L = S.lesson, sess = S.session, on = live(), n = L.steps.length, C = S.course, nx = nextLesson();
+    const L = S.lesson, sess = S.session, on = live(), n = L.steps.length;
     if (lpage === null) lpage = lessonResume();
     lpage = Math.max(0, Math.min(lpage, n + 1));
-    $('#xTitle').textContent = `${S.track_id.toUpperCase()} Lesson${C ? ` · ${C.domain} ${courseIdx() + 1}/${C.lessons.length}` : ''} · ${L.objective} ${L.title}`;
+    $('#xTitle').textContent = `${S.track_id.toUpperCase()} Lesson · ${L.objective} ${L.title}`;
     document.title = `Lesson ${L.objective} · Kubestronaut exam simulator`;
     paintMenus();
     const checked = [...Array(n).keys()].filter(k => stepDone(k)).length, firstOpen = [...Array(n).keys()].find(k => !stepDone(k));
@@ -1091,18 +1027,13 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     $('#qMenu').innerHTML = [...Array(n + 2).keys()].map(p => `<button class="dd-item ${p >= 1 && p <= n && stepDone(p - 1) ? 'pass' : ''}" data-lp="${p}">`
       + (p === 0 ? 'Introduction' : p === n + 1 ? `Wrap-up · ${checked}/${n} steps checked` : `Step ${p} · ${esc(L.steps[p - 1].title)}`) + '</button>').join('');
     $$('#qMenu [data-lp]').forEach(b => b.onclick = () => { lpage = +b.dataset.lp; closeMenus(); paintExam(); $('#qContent').scrollTop = 0; });
-    const pick = !C ? '' : `<div class="line"><b>Lesson ${courseIdx() + 1} of ${C.lessons.length}</b> in ${esc(C.name)}:<select class="select" id="lessonPick">`
-      + C.lessons.map(x => { const c = x.steps.filter(s => s.pass).length;
-          return `<option value="${x.id}"${x.id === C.at ? ' selected' : ''}>${c === x.steps.length ? '✓' : '·'} ${esc(x.objective)} ${esc(x.title)} (${c}/${x.steps.length})</option>`; }).join('')
-      + '</select></div>';
-    let body = `<div class="qhead">${pick}<div class="line"><b>This lesson runs on:</b> <code class="ic" title="click to copy">${esc('ssh ' + L.host)}</code></div>
+    let body = `<div class="qhead"><div class="line"><b>This lesson runs on:</b> <code class="ic" title="click to copy">${esc('ssh ' + L.host)}</code></div>
       <div class="line sub">${L.nodes}-node cluster · files in ${esc(S.workspace)} on that host · no clock</div></div><hr>`;
     if (lpage === 0) {
       body += `<div class="stepsum">Lesson ${esc(L.objective)} · ${n} steps</div><h2 class="qtitle">${esc(L.title)}</h2><div class="qbody">${render(L.intro)}</div>`;
     } else if (lpage === n + 1) {
       body += `<div class="stepsum">Wrap-up · ${checked} of ${n} steps checked</div><h2 class="qtitle">${esc(L.title)}</h2><div class="qbody">${render(L.outro)}</div>`
-        + (on ? `<div class="lstate">${nx ? `<button class="btn btn-primary" id="btnNextLesson">Next lesson · ${esc(nx.objective)} ${esc(nx.title)}</button>` : ''}`
-                + `<button class="btn ${nx ? 'btn-outline-primary' : 'btn-primary'}" id="btnFinish">Finish ${C ? 'the run' : 'lesson'}</button>`
+        + (on ? `<div class="lstate"><button class="btn btn-primary" id="btnFinish">Finish lesson</button>`
                 + (checked < n ? `<span class="lock">${n - checked} step(s) not checked yet - the lesson counts as done only when every step is.</span>` : '') + '</div>' : '');
     } else {
       const k = lpage - 1, s = L.steps[k], r = (sess.steps || {})[k], locked = firstOpen !== undefined && k > firstOpen;
@@ -1120,12 +1051,10 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     copyable($('#qContent'));
     const bs = $('#btnStep'); if (bs) bs.onclick = () => checkStep(lpage - 1);
     const bf = $('#btnFinish'); if (bf) bf.onclick = finishLesson;
-    const bn = $('#btnNextLesson'); if (bn) bn.onclick = () => goLesson(nx.id);
-    const lp = $('#lessonPick'); if (lp) lp.onchange = () => goLesson(lp.value);
     $('#btnFlag').className = 'btn btn-outline-warning hidden';
     $('#btnBack').classList.remove('hidden'); $('#btnBack').disabled = lpage <= 0;
-    $('#btnSatisfied').innerHTML = (lpage === 0 ? 'Start: step 1' : lpage === n ? 'Wrap-up' : lpage === n + 1 ? (nx ? 'Next lesson' : 'Wrap-up') : 'Next step') + ' <span aria-hidden="true">→</span>';
-    $('#btnSatisfied').disabled = lpage >= n + 1 && !nx;
+    $('#btnSatisfied').innerHTML = (lpage === 0 ? 'Start: step 1' : lpage === n ? 'Wrap-up' : lpage === n + 1 ? 'Wrap-up' : 'Next step') + ' <span aria-hidden="true">→</span>';
+    $('#btnSatisfied').disabled = lpage >= n + 1;
     paintDesk();
   }
   async function checkStep(k) {
@@ -1135,12 +1064,10 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     paintExam();
   }
   async function finishLesson() {
-    const n = S.lesson.steps.length, c = [...Array(n).keys()].filter(k => stepDone(k)).length, C = S.course;
-    if (C ? courseDone() < C.lessons.length && !(await ask({title: 'Finish the run?', ok: 'Finish the run',
-          body: `<p class="mb0">${courseDone()} of ${C.lessons.length} lessons have every step checked. The others count as done only when every step is - you can take them again any time.</p>`}))
-        : c < n && !(await ask({title: 'Finish the lesson?', ok: 'Finish lesson',
+    const n = S.lesson.steps.length, c = [...Array(n).keys()].filter(k => stepDone(k)).length;
+    if (c < n && !(await ask({title: 'Finish the lesson?', ok: 'Finish lesson',
         body: `<p class="mb0">${c} of ${n} steps are checked. The lesson counts as done only when every step is - you can take it again any time.</p>`}))) return;
-    $('#busyTitle').textContent = C ? 'Finishing the run' : 'Finishing the lesson';
+    $('#busyTitle').textContent = 'Finishing the lesson';
     $('#busyBody').innerHTML = '<p class="mb0">Nothing is graded: the steps were checked as you went.</p>';
     openModal('#mBusy');
     try { S = await api('/api/end', {}); }
@@ -1196,12 +1123,9 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
   }
   async function terminate() {
     const on = live(), what = isLesson() ? 'lesson' : 'session';
-    const ok = await ask(on && isLesson() && S.course
-      ? {title: 'Terminate the run', ok: 'Terminate the run', okClass: 'btn-danger',
-         body: `<p class="mb0">This deletes the run's ${S.course.lessons.length} hosts right away and ends it. Lessons whose every step was checked stay done; nothing else is recorded.</p>`}
-      : on && isLesson()
+    const ok = await ask(on && isLesson()
       ? {title: 'Terminate the lesson', ok: 'Terminate lesson', okClass: 'btn-danger',
-         body: '<p class="mb0">This deletes the lesson\'s host right away and ends the lesson. Nothing goes into your history or scores; you can take it again any time.</p>'}
+         body: '<p class="mb0">This deletes the lesson\'s host right away and ends the lesson. Nothing is recorded; you can take it again any time.</p>'}
       : on
       ? {title: 'Terminate session', ok: 'Terminate session', okClass: 'btn-danger',
          body: `<div class="alert alert-warning"><p><b>Warning!</b> Terminating this session will:</p><ul><li>delete every host of this session right away;</li><li>end it without grading it - nothing is written to your history.</li></ul></div><p class="mb0">This cannot be undone. Terminate the session?</p>`}
@@ -1214,7 +1138,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     try { S = await api('/api/terminate', {}); }
     catch (e) { alert(e.message === 'not found' ? oldServer('Terminate session') : e.message); return; }
     finally { closeModal('#mBusy'); }
-    if (on) { go('landing'); lobbyNote(`${S.course ? 'Run of lessons' : what === 'lesson' ? 'Lesson' : 'Session'} terminated: nothing was graded, and its hosts are deleted.`); }
+    if (on) { go('landing'); lobbyNote(`${what === 'lesson' ? 'Lesson' : 'Session'} terminated: nothing was graded or recorded, and its hosts are deleted.`); }
     else { route(); alert('The hosts are deleted. Your results and your history stay.'); }
   }
   function toggleFullscreen() {
@@ -1230,27 +1154,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     $('#btnDelete').textContent = lesson ? 'Delete the host' : 'Delete the hosts';
     $('#resLabel').textContent = lesson ? 'Steps checked' : 'Points scored';
   }
-  function paintCourseResults() {
-    const C = S.course, s = S.session, n = C.lessons.length, c = courseDone(), all = c === n;
-    document.title = `Lessons ${C.domain} · Kubestronaut exam simulator`;
-    resultButtons(true);
-    $('#btnDelete').textContent = 'Delete the hosts'; $('#resLabel').textContent = 'Lessons done';
-    $('#resTitle').textContent = `${C.name}: lessons`;
-    $('#resMeta').innerHTML = `${n} lesson${n > 1 ? 's' : ''}, ${C.lessons.reduce((a, x) => a + x.steps.length, 0)} steps<br>Finished ${new Date(s.ended_at * 1000).toLocaleString()}<br>No clock - nothing went into your history`;
-    $('#resEarned').textContent = c; $('#resTotal').textContent = n; $('#resPct').textContent = all ? 'done' : '';
-    $('#resBadge').textContent = all ? 'Every lesson done ✓' : `${n - c} lesson(s) to go`;
-    $('#resBadge').className = 'rank-badge ' + (all ? 'rank-high' : 'rank-mid');
-    $('#resDomains').innerHTML = '';
-    $('#resPath').innerHTML = (s.milestones || []).map(m => `<div class="${m.startsWith('✓') ? 'milestone' : ''}">${esc(m)}</div>`).join('');
-    $('#resQuestions').innerHTML = C.lessons.map(x => { const k = x.steps.filter(t => t.pass).length;
-      return `<div class="qcard ${k === x.steps.length ? 't-pass' : 't-partial'}"><div class="qcard-h"><h3>${esc(x.objective)} · ${esc(x.title)}</h3><span class="qs">${k} of ${x.steps.length}</span></div>
-        <ul class="vitems">${x.steps.map((t, j) => `<li class="vitem"><span>Step ${j + 1} · ${esc(t.title)}</span><span class="vstat ${t.pass ? 'ok' : 'no'}">${t.pass ? '✓' : '✗'}</span></li>`).join('')}</ul><div class="pad"></div></div>`; }).join('');
-    $('#btnDrillMissed').disabled = false;
-    $('#btnDrillMissed').textContent = `Drill ${C.domain} against the clock`;
-    $('#btnDrillMissed').onclick = () => start('drill', null, false, false, C.domain);
-  }
   function paintLessonResults() {
-    if (S.course) return paintCourseResults();
     const L = S.lesson, s = S.session, n = L.steps.length, c = [...Array(n).keys()].filter(k => stepDone(k)).length, all = c === n;
     document.title = `Lesson ${L.objective} · Kubestronaut exam simulator`;
     resultButtons(true);
@@ -1330,7 +1234,7 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
     resetPanels: () => { $('#qpanel').style.width = ''; try { localStorage.removeItem('ksim.split'); } catch (e) { /* fine */ } },
     desktopFullscreen: () => { const f = $('#term'); if (f && f.requestFullscreen) f.requestFullscreen().catch(() => {}); },
     history: showHistory, answers: showAnswers, results: () => go('results'), dashboard: () => go('landing'), review: () => { lpage = null; go('exam'); },
-    finishLesson, retake: () => S.course ? startTeach(S.course.domain) : startLesson(S.lesson.objective),
+    finishLesson, retake: () => startLesson(S.lesson.objective),
   };
   document.addEventListener('click', e => {
     const t = e.target.closest('.dd-toggle');
@@ -1360,7 +1264,6 @@ try { const t = localStorage.getItem('ksim.theme'); if (t === 'light' || t === '
   $('#hardPicker').onchange = e => setHard(e.target.checked);
   $('#pkSession').onchange = pickerChanged;
   $('#pkLesson').onchange = pickerChanged;
-  $('#pkTeach').onchange = pickerChanged;
   $('#pkTrack').onchange = async e => { const keep = $('#pkSession').value; if (await switchTrack(e.target.value)) openPicker(keep); else e.target.value = S.track_id; };
   $('#pkStart').onclick = pickerStart;
   $('#btnBegin').onclick = async () => {