Spec §5.5 encoding conventions; SIGPIPE handling in the CLI; clippy fixes 5b1114a04905

 "libc",

libc = "0.2"

        let l = Signature::decode_list(&Signature::encode_list(std::slice::from_ref(&sig))).unwrap();

        sigs.sort_by_key(|s| s.key);

| **Status** | Draft 0.4b |

### 5.5 Encoding conventions

The field tables in this document give each map key in brackets. Where a structure is a choice between variants, or a compact reference, the following encodings apply:

| Item | Encoding |

|---|---|

| `TreeOp` | Map with key 0 = variant tag: 0 `AddNode`, 1 `RemoveNode`, 2 `Move`, 3 `SetMode`; key 1 = node id; `AddNode` adds 2 kind, 3 mode, 4 parent, 5 name; `RemoveNode` adds 2 placement ref; `Move` adds 2 old placement ref, 4 parent, 5 name; `SetMode` adds 2 old mode ref, 3 mode. |

| `Edit` | Map with key 0 = variant tag: 0 `Insert`, 1 `Delete`, 2 `Replace`; key 1 = node id; `Insert` adds 2 after, 3 before, 4 lines (array of byte strings) or 5 `lines_blob`; `Delete` adds 2 atom ranges; `Replace` adds 2 old (bytes or null), 3 new (bytes or null). |

| `NodeKind` | Unsigned integer: 0 file, 1 dir, 2 symlink. |

| `Mode` | Unsigned integer bit field: bit 0 executable, bit 1 opaque content mode. Directories carry 0. |

| `OpRef` (placement or mode reference) | `[bytes(32) change hash, uint index]`; the all-zero hash means this change. |

| `AtomRef` | `0` for `START`, `1` for `END`, otherwise `[bytes(32) change hash, uint index]` with the all-zero hash meaning this change. |

| `AtomRange` | `[bytes(32) change hash, uint from, uint to]`, half-open, non-empty. |

| `View` (in `Op`) | Key 0 bookmarks: array of `[text name, [bytes(32) heads]]` sorted by name; key 1 workspaces: array of `[bytes(16) id, bytes(32) change]` sorted by id. Remote and tag namespaces are added in later drafts. |

| `Signature` | Map: 0 key id, 1 alg (1 = Ed25519 + ML-DSA-65), 2 Ed25519 bytes(64), 3 ML-DSA-65 bytes(3309). A signature list is a CBOR array of these. |

| Secret key file | Map: 0 version, 1 key id, 2 Ed25519 seed bytes(32), 3 ML-DSA-65 seed bytes(32). Kept only in the user's key directory. |

Atom indices count the atoms one change introduces for one node, in edit order, across all of that change's `Insert` edits on the node.

    loose/            objects written since the last pack, as header || body

    sigs/             signature lists keyed by the ObjectRef they cover (§5.4)

*Changelog.* Draft 0.4b (2026-09-26): §5.5 records the encoding conventions for variants, references, views, signatures, and secret key files; §13.1 adds the signature directory.

Draft 0.4a (2026-09-26): §13.2 pins the FastCDC gear table, rolling hash, and masks so boundaries are identical across implementations.

    // Behave like other CLI tools when output is piped into `head`: die

    // quietly on SIGPIPE instead of panicking on a failed write.

    #[cfg(unix)]

    unsafe {

        libc::signal(libc::SIGPIPE, libc::SIG_DFL);

    }