CodeTailor: accept ===== before test code, and support subgoal labels

[aspadiyath]

Two commits.

1. Accept four or more = before a question's test code.
For book-authored questions, CodeTailor found the unit tests by splitting the activecode source on exactly ====. activecode.js accepts ===== and longer, which older books use, and for those questions the split left a stray = at the top of the tests. Every generated solution then failed with a SyntaxError, and CodeTailor silently fell back to the static example instead of personalizing help. CodeTailor now splits on a line of four or more =, matching activecode.js. This commit stands alone and can be merged separately.

2. Subgoal labels.
Instructors can write subgoal labels (full-line comments naming each step) into a question's backup Parsons problem. Students can write their own in the editor.

• Help before any code: a student who asks for help before writing any code gets a Parsons problem of just the backup's labels, under the function's def line from the starter code. The def is #settled in the settled-block personalization. Untouched starter code counts as no code. This is logged as solution type subgoal_labels.
• Student labels: when a student's code contains labels, the LLM is asked to follow that plan and keep them. They're restored into the personalized solution and puzzle, each above the code it names. Labels are also copied onto paired distractors, so they never reveal which block is correct.
• What isn't a label: commented-out code (# total = 0) isn't treated as a label, comments that ship with the starter code aren't the student's labels, and full-line comments never become draggable blocks.
• Unchanged for existing questions: questions whose backup problem has no comments behave exactly as before.

Testing:
Tested by hand on a local server with py4e-int's list_writeAvgq:

• the labels-only puzzle (graded correct),
• personalized puzzles that keep a student's labels,
• AI_personalized results once the separator issue was out of the way.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

Delimiter compatibility, visible-suffix handling, ambiguous question lookup, and commented-code detection have unresolved correctness issues.

4 open findings

• Match unanchored delimiters used by Activecode · New
• Preserve visible suffix code when truncating editor content · New
• Scope starter lookup to the current base course · New
• Treat commented non-expression Python statements as code · New

What changed in this PR

Adds broader activecode suffix parsing and subgoal-label support for CodeTailor.

Changes:

• Parses longer test delimiters and starter code.
• Generates labels-only puzzles for untouched code.
• Preserves student labels through personalization.

File	Description
subgoal_labels.py	Implements label detection, anchoring, and puzzle creation.
get_personalized_solution.py	Instructs the LLM to preserve labels.
end_to_end.py	Restores labels after testing and block generation.
coach.py	Extracts starter/tests and serves labels-only puzzles.

🧠 Review effort: Balanced

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[aspadiyath]

Fixed Copilot's feedback in 260cb8e

[Copilot]

🟡 Changes recommended

Java commented code is misclassified as labels, and scoped question misses prevent the intended starter-code fallback.

1 open finding

• Scoped lookup miss prevents global question fallback · New

4 resolved since last review

• Treat commented non-expression Python statements as code
• Scope starter lookup to the current base course
• Preserve visible suffix code when truncating editor content
• Match unanchored delimiters used by Activecode

Previously missed (1)

In code that hasn't changed since last review

Java commented code is misclassified as labels

bases/​rsptx/​book_server_api/​routers/​personalized_parsons/​subgoal_labels.py:59

The Java branch treats common commented-out code without a trailing semicolon/brace as a label. For example, // if (x > 0), // int total = 0, and // return total all make is_label_line(..., "java") return true, so backup code can appear as a subgoal and student code can be preserved as a supposed plan. Expand the Java code heuristic to recognize control/declaration/assignment/return syntax, not only line terminators.

🧠 Review effort: Balanced