Two pieces:
1. Lookup helpers walk chain.Levels from leaf back to root. The
"parent applies to descendants unless overridden" cascade rule
means a working/ default_tool=mdedit propagates to deep paths
like working/alice@example.com/notes/sub/deep without anyone
declaring it at every level. AutoOwnAt and VirtualAt follow the
same walk; explicit false at a descendant can override an
ancestor's true (*bool semantics).
2. apps.DefaultAppAt delegates to zddc.DefaultToolAt. The hardcoded
switch on parts[1] (archive→archive, staging→transmittal,
working→mdedit, reviewing→mdedit, mdl→tables) and its case-
sensitivity quirks now live in defaults.zddc.yaml. Operators can
override any of these per-directory with an on-disk .zddc; no
code change required.
Semantic improvement: archive/<party>/incoming previously defaulted
to "archive" (because parts[1]=archive and the switch didn't look
deeper). The new convention routes it to "classifier" — incoming/ is
the bulk-rename surface, not a record browser. Updated
availability_test.go to reflect.
All other DefaultAppAt cases — including case-fold (Archive/MDL),
mdl override, reviewing virtual, project root returning "", random
non-canonical names returning "" — produce bit-identical output.
Two new tests in lookups_test.go cover the propagation:
- TestDefaultToolAt_PropagatesToDescendants
- TestAutoOwnAt_DescendantCanDisable
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>