1529be6fd4
Atomic whole-file replacement (same-dir temp + fsync + rename + parent fsync); the in-memory unit state is authoritative and the file is always the current net state, pretty-printed. Missing files open as empty units and materialize on first write; foreign or unparsable files reject with malformed-medium, stored-version drift with version-mismatch.
25 lines
1.9 KiB
Markdown
25 lines
1.9 KiB
Markdown
# @deepseek-ai/dsh-storage-json
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JSON backend for the [storage hub](../storage/README.md): one human-readable `<unit>.json` file per unit under a configured root, registered as backend `json`. Design: [domain KV storage Agent Note](../../../.agents/notes/proposed/architecture/2026-07-24-domain-kv-storage-and-workspace.zh.md).
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## Model
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- The in-memory unit state is authoritative; every write primitive republishes the whole file via temp-write + fsync + atomic `rename()` replace. A unit file is always the complete current net state — legibility is this backend's reason to exist; scale is the SQLite backend's job.
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- A missing file opens as an empty unit and materializes on the first write. A foreign or unparsable file rejects with `malformed-medium`; a stored version differing from the descriptor rejects with `version-mismatch` (no migration, pre-release stance).
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- Write ordering across calls belongs to the caller (the domain layer's write chain); each single call is atomic and durable once resolved.
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## Config
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| Key | Type | Default | Meaning |
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| --- | --- | --- | --- |
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| `root` | string | required — no default (a cwd fallback would scatter files) | Directory holding unit files; created `0o700` on demand |
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## Model Experience
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No model-visible surface: this package serves host-side persistence only; nothing it does reaches prompts, tool schemas, or token budgets.
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## Known Limitations and Deferred Work
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- Windows durability relies on libuv's `rename()` (`MoveFileExW` with replacement) without an explicit write-through flag; the session-log backend's stricter Win32 write-through publish helper is planned to move down here when the append-log facet lands (see the Agent Note's migration section).
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- No cross-process write locking: two processes writing the same root can interleave whole-file replacements (last write wins). Single-host-process deployments are the current consumer; the multi-process story is deferred per the Agent Note's out-of-scope table.
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