---
# nbd-lins
title: 'Fix nbd graph <id>: show ancestry path through ticket, not just subtree'
status: todo
type: bug
priority: normal
created_at: 2026-03-10T23:30:29Z
updated_at: 2026-03-10T23:30:31Z
blocked_by:
    - nbd-l38k
---

## Problem

Currently `nbd graph <id>` renders the subtree **below** the given ticket via dependent edges (tickets blocked by it). After the graph orientation fix (see ticket 668150), `nbd graph <id>` will render the dependency subtree **below** the given ticket.

But the desired behavior for `nbd graph B` (where A depends on B, C, and D) is more specific:

> `nbd graph B` should graph up to the root level, down to B, and the rest of the way down from B, but not include siblings like C and D.

## Desired behavior

```
A  [todo]  High-level goal
└── B  [todo]  Implement feature B
    └── E  [todo]  Write unit tests for B
```

- A is shown because it depends on B (ancestor)
- C and D are NOT shown (they are sibling dependencies of A, not on the path to B)
- E is shown because B depends on E (B's own dependency subtree)

## Algorithm

1. **Ancestors of B**: traverse the `dependents` edges upward (who depends on B, and who depends on those, etc.) — collecting all ancestor tickets
2. **Filtered ancestor tree**: when rendering ancestors, only show the branch that leads toward B — i.e., at each ancestor, only the child that is on the path to B is shown (not siblings like C and D)
3. **B's dependency subtree**: show B and all its dependencies recursively (as per the corrected subtree logic from ticket 668150)

## Implementation approach

In `src/graph.rs`:
- Add `ancestors(target_id: &str) -> Vec<&str>`: collect all IDs that transitively depend on `target_id` (follow `dependents` edges upward)
- Add `ancestry_path_subtree(target_id: &str) -> ???`: returns the combined view — ancestor tree filtered to the path, plus target's dependency subtree

In `src/display.rs`:
- New or updated `format_subtree()` to render the ancestry+subtree combined view
- The ancestry portion must filter children to only show the branch toward the target (not all dependents of each ancestor)

In `src/main.rs`:
- Update `cmd_graph()` to use the new combined view when an ID is provided

## Edge cases

- If B has no dependents (it is itself a root), just show B's dependency subtree (no ancestor section)
- If B appears in multiple dependency chains, show all paths to it
- Cycle detection still applies (mark revisited nodes with `*`)

## Tests

Add integration tests in `tests/integration.rs`:
- Create tickets A, B, C, D, E with A depending on B/C/D, and B depending on E
- Assert `nbd graph B` output contains A and E but not C and D