feat: add multi-item ingest and Reed-Solomon parity

- Multi-item ingest: each item gets its own Unix socket, Rust processes
  them sequentially into a single snapshot with separate chunk lists
- Reed-Solomon parity: rs(20,1) erasure coding for pack file groups,
  enabling single-pack-loss recovery via parity reconstruction
- Repair now attempts parity-based recovery for missing pack files
- 16 integration tests + 12 Rust unit tests all pass

rust/Cargo.lock

@@ -43,6 +43,17 @@ dependencies = [
  "subtle",
 ]
 
+[[package]]
+name = "ahash"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "891477e0c6a8957309ee5c45a6368af3ae14bb510732d2684ffa19af310920f9"
+dependencies = [
+ "getrandom 0.2.17",
+ "once_cell",
+ "version_check",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "1.1.4"
@@ -141,6 +152,12 @@ version = "1.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
 [[package]]
 name = "bitflags"
 version = "2.11.0"
@@ -282,6 +299,7 @@ dependencies = [
  "flate2",
  "hex",
  "rand",
+ "reed-solomon-erasure",
  "serde",
  "serde_json",
  "sha2",
@@ -429,6 +447,15 @@ dependencies = [
  "polyval",
 ]
 
+[[package]]
+name = "hashbrown"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
+dependencies = [
+ "ahash",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.15.5"
@@ -507,6 +534,15 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "instant"
+version = "0.1.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0242819d153cba4b4b05a5a8f2a7e9bbf97b6055b2a002b395c96b5ff3c0222"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.2"
@@ -547,6 +583,12 @@ version = "0.2.183"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5b646652bf6661599e1da8901b3b9522896f01e736bad5f723fe7a3a27f899d"
 
+[[package]]
+name = "libm"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6d2cec3eae94f9f509c767b45932f1ada8350c4bdb85af2fcab4a3c14807981"
+
 [[package]]
 name = "lock_api"
 version = "0.4.14"
@@ -562,6 +604,15 @@ version = "0.4.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
 
+[[package]]
+name = "lru"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e999beba7b6e8345721bd280141ed958096a2e4abdf74f67ff4ce49b4b54e47a"
+dependencies = [
+ "hashbrown 0.12.3",
+]
+
 [[package]]
 name = "matchers"
 version = "0.2.0"
@@ -634,6 +685,17 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
 
+[[package]]
+name = "parking_lot"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7d17b78036a60663b797adeaee46f5c9dfebb86948d1255007a1d6be0271ff99"
+dependencies = [
+ "instant",
+ "lock_api",
+ "parking_lot_core 0.8.6",
+]
+
 [[package]]
 name = "parking_lot"
 version = "0.12.5"
@@ -641,7 +703,21 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "93857453250e3077bd71ff98b6a65ea6621a19bb0f559a85248955ac12c45a1a"
 dependencies = [
  "lock_api",
- "parking_lot_core",
+ "parking_lot_core 0.9.12",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "60a2cfe6f0ad2bfc16aefa463b497d5c7a5ecd44a23efa72aa342d90177356dc"
+dependencies = [
+ "cfg-if",
+ "instant",
+ "libc",
+ "redox_syscall 0.2.16",
+ "smallvec",
+ "winapi",
 ]
 
 [[package]]
@@ -652,7 +728,7 @@ checksum = "2621685985a2ebf1c516881c026032ac7deafcda1a2c9b7850dc81e3dfcb64c1"
 dependencies = [
  "cfg-if",
  "libc",
- "redox_syscall",
+ "redox_syscall 0.5.18",
  "smallvec",
  "windows-link",
 ]
@@ -759,13 +835,35 @@ dependencies = [
  "getrandom 0.2.17",
 ]
 
+[[package]]
+name = "redox_syscall"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb5a58c1855b4b6819d59012155603f0b22ad30cad752600aadfcb695265519a"
+dependencies = [
+ "bitflags 1.3.2",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.5.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed2bf2547551a7053d6fdfafda3f938979645c44812fbfcda098faae3f1a362d"
 dependencies = [
- "bitflags",
+ "bitflags 2.11.0",
+]
+
+[[package]]
+name = "reed-solomon-erasure"
+version = "6.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7263373d500d4d4f505d43a2a662d475a894aa94503a1ee28e9188b5f3960d4f"
+dependencies = [
+ "libm",
+ "lru",
+ "parking_lot 0.11.2",
+ "smallvec",
+ "spin",
 ]
 
 [[package]]
@@ -904,6 +1002,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "spin"
+version = "0.9.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6980e8d7511241f8acf4aebddbb1ff938df5eebe98691418c4468d0b72a96a67"
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -965,7 +1069,7 @@ dependencies = [
  "bytes",
  "libc",
  "mio",
- "parking_lot",
+ "parking_lot 0.12.5",
  "pin-project-lite",
  "signal-hook-registry",
  "socket2",
@@ -1199,12 +1303,34 @@ version = "0.244.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "47b807c72e1bac69382b3a6fb3dbe8ea4c0ed87ff5629b8685ae6b9a611028fe"
 dependencies = [
- "bitflags",
+ "bitflags 2.11.0",
  "hashbrown 0.15.5",
  "indexmap",
  "semver",
 ]
 
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+
 [[package]]
 name = "windows-core"
 version = "0.62.2"
@@ -1331,7 +1457,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9d66ea20e9553b30172b5e831994e35fbde2d165325bec84fc43dbf6f4eb9cb2"
 dependencies = [
  "anyhow",
- "bitflags",
+ "bitflags 2.11.0",
  "indexmap",
  "log",
  "serde",