Allow non-leaf nodes as correct answers

[aar0npal]

Problem / Intent

Tree tests currently only allow leaf (final-destination) nodes as correct answers. This prevents study owners from setting a parent category as the intended destination — a valid scenario when the goal is to reach a section rather than a specific page.

Approach

The feature is gated by a per-study allowNonLeafAnswers toggle (mirroring randomizeTasks) so existing studies are entirely unaffected when off.

On the participant side, parent rows gain a "Select" button that reveals on hover/focus (desktop) or when the node is expanded (touch), with a gradient text-fade so long labels never collide with the button. The default click on a parent still toggles expand/collapse.

A selected_link column is added to tree_task_results and written at submission time (for both leaf and non-leaf answers). Scoring and Recalculate Stats now compare against this stored value directly, eliminating the resolver heuristic for any new result. Legacy rows (NULL) continue using the existing resolver unchanged.

A secondary fix lands in passing: the setup answer picker was computing non-leaf paths with a different sanitizer than the one tree-tab.tsx uses for leaf links (sanitizeTreeTestLink). This would have caused byte mismatches between owner-saved answers and participant selections — now both sides use the same function.

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Project	Deployment	Actions	Updated (UTC)
usabilitree	Ready	Preview, Comment	Jun 9, 2026 11:35pm

[greptile-apps]

Greptile Summary

This PR adds optional support for non-leaf (parent category) nodes as correct answers in tree tests, gated by a new per-study allowNonLeafAnswers boolean. A selected_link column is also added to tree_task_results so future scoring bypasses the path-resolver heuristic entirely.

• Schema & migration: allow_non_leaf_answers (default false, NOT NULL) added to tree_configs; selected_link (nullable text) added to tree_task_results. Existing studies are unaffected by default.
• Participant UI: When the toggle is on, parent rows in tree-test.tsx gain a "Select" button; handleSelectNonLeaf constructs the canonical path with the same sanitizeTreeTestLink used for leaves, writes selected_link at submission, and correctly propagates pathTaken for directPathTaken scoring.
• Setup / scoring: getAllPaths in tasks-tab.tsx now also enumerates non-leaf paths when the toggle is on (using sanitizeTreeTestLink consistently with the participant side), and saveStudyData / recalculateStudyResults both prefer result.selectedLink over the resolver for new results while gracefully falling back for legacy NULL rows.

Confidence Score: 4/5

Safe to merge for new studies; existing live studies that retroactively adopt non-leaf answers and trigger a stats recalculation on legacy results may see incorrect success flags for those old rows.

The feature is well-scoped and the happy path (new participants on new studies with the toggle enabled) is correctly implemented end-to-end. The one concern is collectValidLinks which exclusively gathers leaf node.link values — if a study owner switches an existing study to non-leaf answers and recalculates (or saves on a live study), the path-resolver fallback for selectedLink = NULL rows can never match a non-leaf expected answer, silently forcing those legacy results to unsuccessful. New results are not affected because selectedLink is written at submission time.

src/lib/treetest/actions.ts — specifically the collectValidLinks helper and the rescoring loops in saveStudyData and recalculateStudyResults that rely on it for NULL-selectedLink rows.

Important Files Changed

Filename	Overview
src/components/tree-test.tsx	Core participant UI change: adds handleSelectNonLeaf with correct sanitizeTreeTestLink path construction, visual state tracking, and pathTaken dedup via appendPath. The immediate onSelect call after setSelectedLink is intentional — dialog overlay prevents re-interaction with the tree while the confidence modal is open.
src/lib/treetest/actions.ts	Ownership checks (eq(studies.userId, user.id)) are properly maintained in both loadStudyData and recalculateStudyResults. Scoring correctly prefers result.selectedLink over the resolver for new rows; legacy NULL rows fall back to resolveSelectedLink which only covers leaf links, which is acceptable since non-leaf selection was impossible before this PR.
src/app/(main)/treetest/setup/[id]/_components/tasks-tab.tsx	getAllPaths now includes non-leaf paths when allowNonLeafAnswers is on, using sanitizeTreeTestLink consistently with the participant side. Validation UI clears correctly when the toggle changes. Minor: checkPathInTree takes an unused _nodes parameter (already deferred to availablePaths set) — cosmetic only.
src/components/tree-preview.tsx	Preview component mirrors the participant UI faithfully. handleSelectNonLeaf only updates local selectedLink (no onSelect submission) which is correct for a preview context. The allowNonLeafAnswers checkbox syncs state bidirectionally with the tasks tab via onAllowNonLeafAnswersChange.
drizzle/0007_happy_cammi.sql	Clean migration: allow_non_leaf_answers defaults to false NOT NULL (preserves existing study behavior); selected_link is nullable text (correct for legacy rows). SQLite treats false as integer 0 since 3.23.0.

_{Reviews (3): Last reviewed commit: "style: fix oxfmt formatting failures in ..." | Re-trigger Greptile}

[aar0npal]

@greptileai review

[aar0npal]

@greptileai review