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+++
title = "Fix nbd graph <id>: show ancestry path through ticket, not just subtree"
priority = 6
status = "todo"
ticket_type = "bug"
dependencies = ["668150"]
+++
## 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