3182da3965
Claude Code keeps per-project memory at <home>/.claude/projects/<key>/,
where <key> is the project's absolute path with every separator and the
drive colon turned into a dash. That makes it both rename-fragile and
machine-specific, and this project has hit each of those once:
- D:\DEV\Schunix -> D:\DEV\SchOS changed the key, and 43 memories were
invisible until moved across by hand.
- Development happens from Windows and from Linux, and each looks in a
different place for the same checkout.
Committing .claude/memory/ fixes both -- git carries it across renames
and between hosts -- and `import` puts it wherever the local machine
expects. .claude/settings.local.json stays ignored: those are per-machine
permissions.
The colon maps to a dash rather than being dropped. Deleting it gives
D-DEV-SchOS, which matches nothing and silently finds zero memories; that
was the first attempt. On Git Bash the key comes from `cygpath -w`,
because Claude Code is a Windows program and sees D:\DEV\SchOS, not
/d/DEV/SchOS.
42 lines
1.9 KiB
Markdown
42 lines
1.9 KiB
Markdown
---
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name: schfs-btree-phase1
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description: "SchFS phase 1 (the CoW B-tree) is built and passing; run `make schfs-test` after touching it"
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metadata:
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node_type: memory
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type: project
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originSessionId: a665e14b-86bd-4b41-a228-51377f3e9225
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modified: 2026-08-01T20:34:28.236Z
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---
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The filesystem is called **SchFS** — not "SchFS v2". Design: `docs/architecture/schfs.md`.
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**Phase 1 is done** (2026-08-01): the copy-on-write B-tree exists and passes its
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torture harness.
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- `include/schfs.h` — on-disk format: 4096-byte blocks, 24-byte
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`(objectid, type, offset)` keys, node header with a self-pointer, uberblock ring.
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- `kernel/fs/schfs/btree.{c,h}` — portable C against an abstract
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`struct schfs_bdev`, so the same code runs on a host file and in the kernel.
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Not yet linked into the kernel.
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- `tools/schfs_test.c` — the harness. **`make schfs-test`** builds and runs it.
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Measured geometry: max inline value 1016 bytes, fanout 84 (internal) / 127 (leaf).
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**Run `make schfs-test` after any change to btree.c.** It checks against a
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reference model, verifies structure, simulates a crash by discarding
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uncommitted writes, and confirms both a bit flip and a misdirected write are
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detected.
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**A test-design trap worth remembering:** the harness originally used
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`schfs_key_cmp` inside its own reference model. Deliberately breaking that
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function then broke the tree *and* the oracle identically, and every check
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still passed — the suite could not fail. The model now has its own
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`ref_key_cmp` written out longhand. Mutation-test any new oracle the same way
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before trusting it.
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Known and deliberate: delete does not merge or rebalance underfull nodes. The
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tree stays correct and sorted; merging is phase 3.
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Next: phase 2 (read-only mount of a v2 image), then writes/transaction groups,
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then extents. Per-pid `/proc` for ps/top should ride along with that VFS work —
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see [[schunix-devfs-procfs]].
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