vibed/nbd/.beans/nbd-l38k--fix-graph-orientation-show-goals-at-root-prerequis.md

title	status	type	priority	created_at	updated_at
Fix graph orientation: show goals at root, prerequisites as leaves	completed	bug	high	2026-03-10T23:30:30Z	2026-03-10T23:30:30Z

Problem

The dependency graph is inverted. Currently:

• Roots = tickets with no dependencies (foundation/leaf-level work)
• Children = dependents of the root (tickets blocked by it)

This means the graph reads bottom-up: you see "what blocks what" rather than "what needs what".

Desired behavior

If ticket A depends on B, C, and D:

• nbd graph should show A at the top with B, C, D indented as children (leaves)
• Roots = tickets with no dependents (nobody depends on them — these are the top-level goals)
• Children = the dependencies of the current node (prerequisites)

This makes the graph read naturally: goals at the top, work to be done first at the bottom.

Files to change

src/graph.rs

• roots(): change predicate from node.dependencies.is_empty() to node.dependents.is_empty()
• subtree() + dfs_subtree(): currently traverses dependents edges; should traverse dependencies edges so subtree(A) returns A + what A depends on (recursively)
• to_json_value() and to_subtree_json_value(): edge direction in JSON output should be {"from": dependent_id, "to": dependency_id} (A→B means A depends on B), or reconsider the from/to labels in light of the new orientation
• Update all doc comments to reflect the new semantics

src/display.rs

• render_node(): iterate node.dependencies as children (not node.dependents)
• Update doc comments for format_graph() and format_subtree()

src/graph.rs module-level doc comment

The edge semantics paragraph should be updated: "A is a dependency of B" means A appears as a child in the tree of B.

Tests

Update any graph-related tests in src/tests.rs and tests/integration.rs that assert the current (inverted) traversal order.