draft-fossil-submanifests-00 §7.4: enumeration results SHOULD be cached keyed by artifact name, so a rebuild parses each distinct sub-manifest once. The tree walk's loader now serves a resolved node from, and keeps it in, a new byte-bounded LRU memo on content.Cache (DerivedSized), keyed by the node's hash and charged its bytes, within a quarter of the cache's budget. The existing 32-entry Derived FIFO is sized for a few parsed check-ins; a tree's working set is every distinct node, which would thrash it and evict those check-ins.

Only a node that resolved is kept, so a phantom is looked up afresh and fails the walk as before. Depth, cycle and node-count bounds stay per walk. The memo is dropped with Derived on Invalidate and Clear, and the Repo's cache is replaced at every write.

Listing a tree that differs from one already read in one leaf now parses its manifest and that leaf; listing every check-in of zit's recorded tree history parses 48 sub-manifests instead of 109. SM-7.4-1 is covered.

Tracked in #493. check-in: 94f61db228 user: [email protected] tags: main, trunk