diff --git a/.gitignore b/.gitignore
index 3c449e44..43ee92a1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -486,3 +486,6 @@ build/
 # Generated fresh by the runner on each CI run. Committing a local copy
 # would label this machine capabilities as the runner is, which is a lie.
 gates/runnability-ci.tsv
+
+# Per-course virtualenvs created by ./run.sh run.
+.venv/
diff --git a/DOCS-runnability.md b/DOCS-runnability.md
index 15ee9fad..0ebbda11 100644
--- a/DOCS-runnability.md
+++ b/DOCS-runnability.md
@@ -39,7 +39,7 @@ run cannot clobber the local column.
 | `Programming/ECOAR` | runnable | - | make |
 | `Programming/ECOTE` | runnable | - | python3 /home/kuhy/WUT_Computer_Science/Programming/ECOTE/program/translator/main.py |
 | `Programming/ECRYPT` | no-code | - | test1.py is a 0-byte stub; this course produced no submitted code |
-| `Programming/ECRYPT_PROJECT` | runnable | - | python3 /home/kuhy/WUT_Computer_Science/Programming/ECRYPT_PROJECT/code |
+| `Programming/ECRYPT_PROJECT` | runnable | - | python3 the entry script |
 | `Programming/EGUI` | runnable | - | dotnet build |
 | `Programming/EOOP` | runnable | - | compiles each standalone .cpp |
 | `Programming/EOPSY` | runnable | - | make |
@@ -47,12 +47,12 @@ run cannot clobber the local column.
 | `Programming/E-PSYOPS` | runnable | - | opens in the Unity editor |
 | `Programming/ERSMS-project` | runnable | - | docker compose up |
 | `Programming/NLP` | runnable | - | python3 the entry script |
-| `Programming/PBAD` | runnable | - | jupyter nbconvert --execute |
-| `Programming/PORR` | runnable | - | python3 /home/kuhy/WUT_Computer_Science/Programming/PORR/code |
+| `Programming/PBAD` | blocked | - | jupyter is on PATH but broken (bad interpreter) |
+| `Programming/PORR` | runnable | - | python3 /home/kuhy/WUT_Computer_Science/Programming/PORR/code/main.py |
 | `Programming/PSD` | runnable | - | starts the Kafka/Flink stack (installs packages with sudo) |
 | `Programming/psd_project` | runnable | - | mvn package |
 | `Programming/TRAK` | runnable | - | python3 the entry script |
-| `Programming/twm_4` | runnable | - | jupyter nbconvert --execute |
+| `Programming/twm_4` | blocked | - | jupyter is on PATH but broken (bad interpreter) |
 | `Programming/USD` | no-code | - | README describes a MetaDrive RL assignment; no implementation was submitted |
 | `Programming/WDWR` | runnable | - | python3 the entry script |
 | `Programming/ZPOB` | runnable | - | builds the report with latexmk |
diff --git a/NotProgramming/EDABA-LAB/textual-description/description.tex b/NotProgramming/EDABA-LAB/textual-description/description.tex
index 48afe888..e16a59d0 100644
--- a/NotProgramming/EDABA-LAB/textual-description/description.tex
+++ b/NotProgramming/EDABA-LAB/textual-description/description.tex
@@ -1,4 +1,8 @@
 \documentclass{report}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{graphicx}
 \usepackage{hyperref}
 \usepackage{pdfpages}
diff --git a/NotProgramming/SDM/presentations/my_thesis/main.tex b/NotProgramming/SDM/presentations/my_thesis/main.tex
index ee535b12..9bb3066c 100644
--- a/NotProgramming/SDM/presentations/my_thesis/main.tex
+++ b/NotProgramming/SDM/presentations/my_thesis/main.tex
@@ -300,7 +300,7 @@
           \item Intuicyjność
           \item Materiały 
           \item Zasoby (Assety)  
-	  \item Dostępne funkcje}
+	  \item Dostępne funkcje
 	  \item ChatGPT
         \end{itemize}
       \end{frame}
diff --git a/NotProgramming/SDM2/presentations/my_thesis/main.tex b/NotProgramming/SDM2/presentations/my_thesis/main.tex
index 324fdc4c..04ec5a27 100644
--- a/NotProgramming/SDM2/presentations/my_thesis/main.tex
+++ b/NotProgramming/SDM2/presentations/my_thesis/main.tex
@@ -1,4 +1,8 @@
 \documentclass{beamer}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 
 \usepackage[fontsize=20pt]{fontsize}
 \usepackage{graphicx}
diff --git a/NotProgramming/SPD/lab1/main.tex b/NotProgramming/SPD/lab1/main.tex
index f98644cc..e15d715a 100644
--- a/NotProgramming/SPD/lab1/main.tex
+++ b/NotProgramming/SPD/lab1/main.tex
@@ -1,6 +1,9 @@
 \documentclass[12pt]{article}
 \usepackage[polish]{babel}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{array}
 \usepackage{float}
 \usepackage{graphicx} % Add this line to include graphics
diff --git a/NotProgramming/STUP/report.tex b/NotProgramming/STUP/report.tex
index dcd3043b..b57efd84 100644
--- a/NotProgramming/STUP/report.tex
+++ b/NotProgramming/STUP/report.tex
@@ -1,4 +1,8 @@
 \documentclass[12pt]{extreport}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 
 
 \begin{document}
diff --git a/Programming/AIS/report/final/ver1/main.tex b/Programming/AIS/report/final/ver1/main.tex
index b3be20c6..4abccb2c 100644
--- a/Programming/AIS/report/final/ver1/main.tex
+++ b/Programming/AIS/report/final/ver1/main.tex
@@ -1,4 +1,8 @@
 \documentclass[a4paper,12pt]{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 
 % Packages
 \usepackage{amsmath, amssymb, amsthm} % For math symbols and theorems
diff --git a/Programming/AIS/report/final/ver2/etoll.tex b/Programming/AIS/report/final/ver2/etoll.tex
index 2924d53d..c0e8ae93 100644
--- a/Programming/AIS/report/final/ver2/etoll.tex
+++ b/Programming/AIS/report/final/ver2/etoll.tex
@@ -2,6 +2,9 @@
 \usepackage[left=0.75in,right=0.75in,bottom=0.75in]{geometry}
 \usepackage[polish]{babel}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{hyperref}
 \usepackage{graphicx}
 \usepackage{enumitem}
diff --git a/Programming/BSS/lab1/report_1.tex b/Programming/BSS/lab1/report_1.tex
index edde3448..7899cdbc 100644
--- a/Programming/BSS/lab1/report_1.tex
+++ b/Programming/BSS/lab1/report_1.tex
@@ -1,4 +1,10 @@
-\documentclass{article}[12pt]
+% Options belong BEFORE the class name; this read
+% \documentclass{article}[12pt], where [12pt] is not a class option at all.
+\documentclass[12pt]{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{graphicx}
 
 \title{[BSS]-Lab1-śr16-KrzysztofRudnicki}
diff --git a/Programming/E-PSYOPS/projectConcept/main.tex b/Programming/E-PSYOPS/projectConcept/main.tex
index 72121d22..15995e84 100644
--- a/Programming/E-PSYOPS/projectConcept/main.tex
+++ b/Programming/E-PSYOPS/projectConcept/main.tex
@@ -1,5 +1,8 @@
 \documentclass{article}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{listings}
 \usepackage{xcolor}
 \usepackage{graphicx}
diff --git a/Programming/EARIN/project/preliminary/report.tex b/Programming/EARIN/project/preliminary/report.tex
index dca03d66..9b8f1d0d 100644
--- a/Programming/EARIN/project/preliminary/report.tex
+++ b/Programming/EARIN/project/preliminary/report.tex
@@ -1,4 +1,8 @@
 \documentclass[12pt]{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{graphicx} % Required for inserting images
 \usepackage{hyperref}
 
diff --git a/Programming/ECOTE/run.sh b/Programming/ECOTE/run.sh
index 9252dc47..d7df3ad1 100755
--- a/Programming/ECOTE/run.sh
+++ b/Programming/ECOTE/run.sh
@@ -9,4 +9,5 @@ set -euo pipefail
 
 course_main --kind python \
     --entry "$(dirname "$(readlink -f "$0")")/program/translator/main.py" \
+    --test-dir "$(dirname "$(readlink -f "$0")")/program" \
     -- "$@"
diff --git a/Programming/ECRYPT_PROJECT/report/report.tex b/Programming/ECRYPT_PROJECT/report/report.tex
index e649bea4..85bef6e2 100644
--- a/Programming/ECRYPT_PROJECT/report/report.tex
+++ b/Programming/ECRYPT_PROJECT/report/report.tex
@@ -1,4 +1,8 @@
 \documentclass[12pt]{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{hyperref}
 \usepackage{graphicx}
 \usepackage{float}
diff --git a/Programming/ECRYPT_PROJECT/run.sh b/Programming/ECRYPT_PROJECT/run.sh
index f441b9a5..9f3fa5a5 100755
--- a/Programming/ECRYPT_PROJECT/run.sh
+++ b/Programming/ECRYPT_PROJECT/run.sh
@@ -7,6 +7,8 @@ set -euo pipefail
 # shellcheck source=../../scripts/course_lib.sh
 . "$(dirname "$(readlink -f "$0")")/../../scripts/course_lib.sh"
 
+# No --entry on purpose: code/project.py prompts on stdin, so it cannot be run
+# headlessly. This course ships a real pytest suite, and that is the check.
 course_main --kind python \
-    --entry "$(dirname "$(readlink -f "$0")")/code" \
+    --test-dir "$(dirname "$(readlink -f "$0")")/sieve" \
     -- "$@"
diff --git a/Programming/ECRYPT_PROJECT/code/C-100000.csv b/Programming/ECRYPT_PROJECT/sieve/C-100000.csv
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/C-100000.csv
rename to Programming/ECRYPT_PROJECT/sieve/C-100000.csv
diff --git a/Programming/ECRYPT_PROJECT/code/P-100000.csv b/Programming/ECRYPT_PROJECT/sieve/P-100000.csv
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/P-100000.csv
rename to Programming/ECRYPT_PROJECT/sieve/P-100000.csv
diff --git a/Programming/ECRYPT_PROJECT/code/__init__.py b/Programming/ECRYPT_PROJECT/sieve/__init__.py
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/__init__.py
rename to Programming/ECRYPT_PROJECT/sieve/__init__.py
diff --git a/Programming/ECRYPT_PROJECT/code/conftest.py b/Programming/ECRYPT_PROJECT/sieve/conftest.py
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/conftest.py
rename to Programming/ECRYPT_PROJECT/sieve/conftest.py
diff --git a/Programming/ECRYPT_PROJECT/code/project.py b/Programming/ECRYPT_PROJECT/sieve/project.py
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/project.py
rename to Programming/ECRYPT_PROJECT/sieve/project.py
diff --git a/Programming/ECRYPT_PROJECT/code/test_main.py b/Programming/ECRYPT_PROJECT/sieve/test_main.py
similarity index 100%
rename from Programming/ECRYPT_PROJECT/code/test_main.py
rename to Programming/ECRYPT_PROJECT/sieve/test_main.py
diff --git a/Programming/EOOP/Various/currency/currency.cpp b/Programming/EOOP/Various/currency/currency.cpp
index e81d6f02..d83af483 100755
--- a/Programming/EOOP/Various/currency/currency.cpp
+++ b/Programming/EOOP/Various/currency/currency.cpp
@@ -15,7 +15,7 @@
    g++ -Wall -Wextra -Werror -pedantic lab_2.cpp currency.hpp
  */
 
-#include "currency2.hpp"
+#include "currency.hpp"
 #include <iostream>
 
 int main() {
diff --git a/Programming/ERSMS-project/docs/final_documentation/main.tex b/Programming/ERSMS-project/docs/final_documentation/main.tex
index b059a8f8..868ea8b6 100644
--- a/Programming/ERSMS-project/docs/final_documentation/main.tex
+++ b/Programming/ERSMS-project/docs/final_documentation/main.tex
@@ -1,4 +1,8 @@
-\documentclass{article}[11pt]
+\documentclass{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}[11pt]
 \usepackage{graphicx}
 \usepackage{float}
 
diff --git a/Programming/PORR/report/first_part/main.tex b/Programming/PORR/report/first_part/main.tex
index 443ca457..b4222dd0 100644
--- a/Programming/PORR/report/first_part/main.tex
+++ b/Programming/PORR/report/first_part/main.tex
@@ -1,4 +1,8 @@
 \documentclass[12pt]{article}
+\usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{pgfplots}
 \usepgfplotslibrary{groupplots}
 \pgfplotsset{compat=1.17}
diff --git a/Programming/PORR/run.sh b/Programming/PORR/run.sh
index eb6f060e..7b687781 100755
--- a/Programming/PORR/run.sh
+++ b/Programming/PORR/run.sh
@@ -8,5 +8,5 @@ set -euo pipefail
 . "$(dirname "$(readlink -f "$0")")/../../scripts/course_lib.sh"
 
 course_main --kind python \
-    --entry "$(dirname "$(readlink -f "$0")")/code" \
+    --entry "$(dirname "$(readlink -f "$0")")/code/main.py" \
     -- "$@"
diff --git a/Programming/PSD/zin1/zin1.tex b/Programming/PSD/zin1/zin1.tex
index ad045bf8..f92ba3a6 100644
--- a/Programming/PSD/zin1/zin1.tex
+++ b/Programming/PSD/zin1/zin1.tex
@@ -1,6 +1,9 @@
 \documentclass[a4paper, 12pt]{article}
 \usepackage{graphicx}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage[polish]{babel}  % Add Polish language support
 
 % Default fixed font does not support bold face
diff --git a/Programming/WDWR/project/report/report.tex b/Programming/WDWR/project/report/report.tex
index 0fced065..c5fdd1f5 100644
--- a/Programming/WDWR/project/report/report.tex
+++ b/Programming/WDWR/project/report/report.tex
@@ -1,6 +1,9 @@
 \documentclass[12pt]{article}
 \usepackage[polish]{babel}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{amsmath}
 \usepackage{amsfonts}
 \usepackage{amssymb}
diff --git a/Programming/WDWR/projekt/doc/main.tex b/Programming/WDWR/projekt/doc/main.tex
index 76ffec82..e261645b 100644
--- a/Programming/WDWR/projekt/doc/main.tex
+++ b/Programming/WDWR/projekt/doc/main.tex
@@ -1,5 +1,8 @@
 \documentclass{article}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \usepackage{polski}
 \usepackage{amsmath}
 \usepackage{relsize,amsfonts}
diff --git a/Programming/ZPOB/esej/esej.tex b/Programming/ZPOB/esej/esej.tex
index ad919c8a..1ab6ec69 100644
--- a/Programming/ZPOB/esej/esej.tex
+++ b/Programming/ZPOB/esej/esej.tex
@@ -2,6 +2,9 @@
 \usepackage[polish]{babel}
 \usepackage[polish]{babel}
 \usepackage[utf8]{inputenc}
+% T1 is required for Polish ogonek characters; without it pdflatex
+% fails with "Command \k unavailable in encoding OT1".
+\usepackage[T1]{fontenc}
 \author{Krzysztof Rudnicki, 307585}
 \title{ZBOP esej \\ Organizacja systemów produkcyjnych}
 \subtitle{ze względu na sposób spłenienia zapotrzebowania}
diff --git a/gates/known-incomplete.txt b/gates/known-incomplete.txt
new file mode 100644
index 00000000..3260775a
--- /dev/null
+++ b/gates/known-incomplete.txt
@@ -0,0 +1,15 @@
+# Source files that cannot build because something they need was never
+# submitted. One repo-relative path per line, with the reason and how it was
+# checked above it.
+#
+# This is NOT a lint allowlist. Nothing here is a style exception; each entry
+# is a factual statement that a dependency is absent from the archive, and the
+# check is `git log --all -- <missing file>` coming back empty. Fabricating the
+# missing file would be inventing coursework that was never handed in.
+#
+# Read by scripts/course_lib.sh, which skips these and says why.
+
+# Includes "set.hpp", which does not exist here and never has:
+#   git log --all --name-only -- '*set.hpp'  ->  no results
+# The header was supplied by the course and only the .cpp was submitted.
+Programming/EOOP/Various/set/set.cpp
diff --git a/gates/runnability-local.tsv b/gates/runnability-local.tsv
index 98cc7133..d61d5f21 100644
--- a/gates/runnability-local.tsv
+++ b/gates/runnability-local.tsv
@@ -25,7 +25,7 @@ Programming/EARIN	runnable	python3 the entry script
 Programming/ECOAR	runnable	make
 Programming/ECOTE	runnable	python3 /home/kuhy/WUT_Computer_Science/Programming/ECOTE/program/translator/main.py
 Programming/ECRYPT	no-code	test1.py is a 0-byte stub; this course produced no submitted code
-Programming/ECRYPT_PROJECT	runnable	python3 /home/kuhy/WUT_Computer_Science/Programming/ECRYPT_PROJECT/code
+Programming/ECRYPT_PROJECT	runnable	python3 the entry script
 Programming/EGUI	runnable	dotnet build
 Programming/EOOP	runnable	compiles each standalone .cpp
 Programming/EOPSY	runnable	make
@@ -33,12 +33,12 @@ Programming/EPFU	runnable	make
 Programming/E-PSYOPS	runnable	opens in the Unity editor
 Programming/ERSMS-project	runnable	docker compose up
 Programming/NLP	runnable	python3 the entry script
-Programming/PBAD	runnable	jupyter nbconvert --execute
-Programming/PORR	runnable	python3 /home/kuhy/WUT_Computer_Science/Programming/PORR/code
+Programming/PBAD	blocked	jupyter is on PATH but broken (bad interpreter)
+Programming/PORR	runnable	python3 /home/kuhy/WUT_Computer_Science/Programming/PORR/code/main.py
 Programming/PSD	runnable	starts the Kafka/Flink stack (installs packages with sudo)
 Programming/psd_project	runnable	mvn package
 Programming/TRAK	runnable	python3 the entry script
-Programming/twm_4	runnable	jupyter nbconvert --execute
+Programming/twm_4	blocked	jupyter is on PATH but broken (bad interpreter)
 Programming/USD	no-code	README describes a MetaDrive RL assignment; no implementation was submitted
 Programming/WDWR	runnable	python3 the entry script
 Programming/ZPOB	runnable	builds the report with latexmk
diff --git a/scripts/course_lib.sh b/scripts/course_lib.sh
index 29e46eec..52050655 100644
--- a/scripts/course_lib.sh
+++ b/scripts/course_lib.sh
@@ -20,6 +20,9 @@ readonly COURSE_EXIT_NO_CODE=79
 
 COURSE_ROOT="$(cd "$(dirname "$(readlink -f "${BASH_SOURCE[1]}")")" && pwd)"
 readonly COURSE_ROOT
+# Repo root is two levels up: every course dir is <repo>/<area>/<course>.
+COURSE_GATES="$(cd "${COURSE_ROOT}/../.." && pwd)/gates"
+readonly COURSE_GATES
 
 # --- helpers -----------------------------------------------------------------
 
@@ -65,6 +68,14 @@ _probe_any() {
     _blocked "needs $label (none of: $*)"
 }
 
+# True if the path is recorded in gates/known-incomplete.txt.
+_is_known_incomplete() {
+    local manifest="${COURSE_GATES:-}/known-incomplete.txt"
+    [[ -f "$manifest" ]] || return 1
+    local rel="$1"
+    grep -vE '^\s*#|^\s*$' "$manifest" | grep -qxF "$rel"
+}
+
 _first_file() {
     find "$COURSE_ROOT" -name "$1" -not -path '*/node_modules/*' -print -quit 2>/dev/null
 }
@@ -118,6 +129,10 @@ _probe() {
             ;;
         notebook)
             _have jupyter || _blocked "needs jupyter"
+            # Being on PATH is not the same as working: this machine has a
+            # jupyter shim whose pipx venv interpreter is gone, so it fails
+            # with "bad interpreter". Probe by actually invoking it.
+            jupyter --version > /dev/null 2>&1 || _blocked "jupyter is on PATH but broken (bad interpreter)"
             _runnable "jupyter nbconvert --execute"
             ;;
         compose)
@@ -129,6 +144,63 @@ _probe() {
     esac
 }
 
+# Use the course venv when one exists, otherwise the system interpreter.
+_python_bin() {
+    if [[ -x "$COURSE_ROOT/.venv/bin/python" ]]; then
+        printf '%s' "$COURSE_ROOT/.venv/bin/python"
+    else
+        printf 'python3'
+    fi
+}
+
+# Dependencies are the runner's job, not the reader's. Without this, EARIN
+# dies on ModuleNotFoundError for gymnasium and the "runnable" status is a lie.
+_python_install_requirements() {
+    local reqs=()
+    while IFS= read -r r; do reqs+=("$r"); done < <(
+        find "$COURSE_ROOT" -name 'requirements*.txt' -not -path '*/.venv/*' | sort)
+    [[ ${#reqs[@]} -gt 0 ]] || return 0
+
+    if [[ ! -x "$COURSE_ROOT/.venv/bin/python" ]]; then
+        printf 'creating .venv\n'
+        python3 -m venv "$COURSE_ROOT/.venv"
+    fi
+    "$COURSE_ROOT/.venv/bin/python" -m pip install --quiet --upgrade pip
+
+    # EVERY requirements file, not just the first: EARIN is six independent
+    # labs plus a project, and installing only one of them left the lab it
+    # then tried to run missing gymnasium.
+    local req
+    for req in "${reqs[@]}"; do
+        printf 'installing %s\n' "${req#"$COURSE_ROOT"/}"
+        "$COURSE_ROOT/.venv/bin/python" -m pip install --quiet -r "$req" || {
+            printf 'warning: some requirements in %s failed\n' "${req#"$COURSE_ROOT"/}" >&2
+        }
+    done
+}
+
+# Where a course ships real tests, running them is a stronger check than
+# running the program -- and for an interactive program (ECRYPT_PROJECT prompts
+# on stdin) it is the ONLY check that works without a person at a keyboard.
+_python_run_tests() {
+    local suite
+    suite="$(find "$COURSE_ROOT" -name 'test_*.py' -not -path '*/.venv/*' -print -quit 2>/dev/null)"
+    [[ -n "$suite" ]] || return 0
+    local py
+    py="$(_python_bin)"
+    "$py" -c 'import pytest' 2> /dev/null || {
+        printf 'tests present but pytest is not installed; skipping\n'
+        return 0
+    }
+    # Which directory pytest runs FROM is course-specific and cannot be
+    # guessed: ECOTE needs program/ so `from translator.main import` resolves,
+    # ECRYPT_PROJECT needs sieve/ because its fixtures open P-100000.csv by a
+    # relative path. So the stub says, and COURSE_ROOT is only the default.
+    local from_dir="${COURSE_TEST_DIR:-$COURSE_ROOT}"
+    printf 'running the test suite in %s\n' "${from_dir#"$COURSE_ROOT"/}"
+    ( cd "$from_dir" && "$py" -m pytest -q )
+}
+
 # --- runners -----------------------------------------------------------------
 
 _run() {
@@ -156,9 +228,41 @@ _run() {
             ;;
         python)
             local entry="${COURSE_ENTRY:-}"
-            [[ -n "$entry" ]] || entry="$(_first_file 'main.py')"
-            [[ -n "$entry" ]] || _no_code "no entry point; see this directory's README"
-            ( cd "$(dirname "$entry")" && python3 "$(basename "$entry")" )
+            # An entry may be given as a directory; resolve it to the module
+            # inside. Passing the directory itself makes python look for
+            # __main__.py and fail with a message about the wrong thing.
+            if [[ -d "$entry" ]]; then
+                local cand
+                for cand in main.py project.py __main__.py; do
+                    if [[ -f "$entry/$cand" ]]; then
+                        entry="$entry/$cand"
+                        break
+                    fi
+                done
+            fi
+            # Only auto-pick a main.py when there is exactly ONE. A course
+            # with six labs has six, and choosing whichever find returns first
+            # is not "running the project", it is running an arbitrary lab.
+            if [[ ! -f "$entry" ]]; then
+                local mains
+                mains="$(find "$COURSE_ROOT" -name 'main.py' -not -path '*/.venv/*' | wc -l)"
+                [[ "$mains" -eq 1 ]] && entry="$(_first_file 'main.py')"
+            fi
+
+            _python_install_requirements
+
+            if [[ -f "$entry" ]]; then
+                ( cd "$(dirname "$entry")" && "$(_python_bin)" "$(basename "$entry")" )
+            else
+                # A pile of one-shot scripts with no entry contract (NLP is
+                # the case here). Syntax-check them all rather than picking one
+                # arbitrarily and calling that "running the project".
+                printf 'no single entry point; syntax-checking every module instead\n'
+                find "$COURSE_ROOT" -name '*.py' -not -path '*/.venv/*' -print0 \
+                    | xargs -0 -r "$(_python_bin)" -m py_compile
+                printf 'all modules compile\n'
+            fi
+            _python_run_tests
             ;;
         node)    ( cd "${COURSE_ENTRY:-$COURSE_ROOT}" && npm install && npm start ) ;;
         maven)   ( cd "${COURSE_ENTRY:-$COURSE_ROOT}" && mvn -q package ) ;;
@@ -177,6 +281,10 @@ _run() {
             mkdir -p "$COURSE_ROOT/build"
             while IFS= read -r src; do
                 rel="${src#"$COURSE_ROOT"/}"
+                if _is_known_incomplete "${src#"${COURSE_GATES%/gates}"/}"; then
+                    printf 'skipping  %s (see gates/known-incomplete.txt)\n' "$rel"
+                    continue
+                fi
                 out="$COURSE_ROOT/build/$(basename "${rel%.cpp}")"
                 # Some files here are exam-answer fragments with no main(), so
                 # they cannot be linked. Compile those to an object instead --
@@ -211,11 +319,13 @@ course_main() {
     COURSE_KIND=""
     COURSE_ENTRY=""
     COURSE_NOTE=""
+    COURSE_TEST_DIR=""
     while [[ $# -gt 0 ]]; do
         case "$1" in
             --kind)  COURSE_KIND="$2"; shift 2 ;;
             --entry) COURSE_ENTRY="$2"; shift 2 ;;
             --note)  COURSE_NOTE="$2"; shift 2 ;;
+            --test-dir) COURSE_TEST_DIR="$2"; shift 2 ;;
             --) shift; break ;;
             *) break ;;
         esac