OUTPUT FORMATS:

MARKDOWN (default, -f markdown):
  ## Documents

  Found 3 results:

  - [Document A](doc-a) (root)
  - [Document B](doc-b) <- [Document A](doc-a)

  Each result shows:
  - Document link
  - (root) indicator if no parents
  - Parent documents with <- notation (where this doc is embedded)

KEYS (-f keys):
  One key per line, suitable for piping:

    doc-a
    doc-b
    doc-c

JSON (-f json):
  Structured output with metadata:

    {"query": "...", "total": 3, "results": [
      {"key": "...", "title": "...", "is_root": true,
       "incoming_refs": 5, "outgoing_refs": 2, "parent_documents": [...]}]}

STRUCTURAL SET SELECTOR (--in family):

  --in KEY[:DEPTH]      Sub-documents of EVERY listed key (AND). Repeatable.
                        KEY:DEPTH overrides --max-depth per entry.
  --in-any KEY[:DEPTH]  Sub-documents of AT LEAST ONE listed key (OR).
  --not-in KEY[:DEPTH]  Exclude sub-documents of any listed key (NOT).
  --max-depth N         Default depth for entries without :DEPTH. Unbounded if omitted.

EXAMPLES:

  # Sub-documents of A AND B (intersection, unbounded)
  iwe find --in projects/alpha --in people/dmytro

  # Per-parent depth: A within 3 hops, Dmytro within 1
  iwe find --in projects/alpha:3 --in people/dmytro:1

  # Sub-documents of A OR B (union)
  iwe find --in-any projects/alpha --in-any projects/beta

  # Sub-documents of A but NOT in archive
  iwe find --in projects/alpha --not-in archive
