build: declare Rust 1.92 as the MSRV and check it in CI

rust-version = "1.92" in [workspace.package], inherited by every crate.
1.92 is the floor: wgpu (clawhdf5-gpu) requires it, and the whole
workspace, Python bindings included, checks cleanly on it. ci-test.sh
reads the version from Cargo.toml and checks the workspace on exactly
that toolchain, so the manifests and the README badge cannot drift from
what actually builds. The badge said 1.75, below edition 2024's own
floor.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

CHANGELOG.md

@@ -11,6 +11,8 @@
   overrides zlib-rs wherever it is on.
 - **A truncated deflate chunk is now an error.** It used to read back short,
   with no error.
+- **Minimum supported Rust is 1.92**, now declared in every crate's
+  `rust-version` and checked in CI.
 - **New stores use the int8 vector index by default.**
   `MemoryConfig::quantized_index` now defaults to `true`: a quarter of the
   index memory, builds 1.8x (x86-64) and 2.3x (Raspberry Pi 5) faster, and
@@ -32,6 +34,8 @@
   no `std`, cannot detect SIMD at runtime, and inflates 3.5x slower; the
   workspace builds flate2 with `default-features = false`, which had been
   switching it off.
+- `rust-version = "1.92"` for the whole workspace (the floor: `wgpu` requires
+  it), and CI checks the workspace on exactly that toolchain.
 - CI keeps zlib-ng building and tested; the arm64 job no longer needs cmake.
 
 ### Correctness

CLAUDE.md

@@ -31,7 +31,8 @@ Cargo workspace with 16 crates under `crates/` (plus `libaec-sys`, an internal F
   pure-Rust zlib-rs (`fast-deflate` opts into zlib-ng, which needs cmake).
   `ci-test.sh` fails if a C-building crate enters the core crates' default
   tree. flate2 must keep `runtime_detection` with zlib-rs — without it zlib-rs
-  loses SIMD and inflates 3.5x slower.
+  loses SIMD and inflates 3.5x slower. MSRV is 1.92 (`rust-version`, checked
+  in CI).
 - HNSW vector index for semantic similarity search over agent memories — the
   `clawhdf5-agent` `hnsw` feature is **on by default**, so `hybrid_search` uses
   the approximate `clawhdf5-ann` index for the vector stage (the index mirrors

Cargo.toml

@@ -23,6 +23,9 @@ resolver = "2"
 [workspace.package]
 version = "2.7.0"
 edition = "2024"
+# Oldest toolchain that builds the whole workspace; CI checks it. wgpu (in
+# clawhdf5-gpu) requires 1.92.
+rust-version = "1.92"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"
 

README.md

@@ -3,7 +3,7 @@
 **The memory layer AI agents deserve. One file. Pure Rust. Zero C dependencies.**
 
 [![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
-[![Rust](https://img.shields.io/badge/rust-1.94%2B-orange.svg)](https://www.rust-lang.org)
+[![Rust](https://img.shields.io/badge/rust-1.92%2B-orange.svg)](https://www.rust-lang.org)
 [![Tests](https://img.shields.io/badge/tests-1850%2B-brightgreen.svg)](#building)
 [![LongMemEval](https://img.shields.io/badge/LongMemEval__s-Turn--Level%20Hit@5%2081.4%25%20hybrid-blue.svg)](BENCHMARKS.md#longmemeval-results)
 [![Footprint](https://img.shields.io/badge/on--disk-1.7%20KB%2Frecord-lightgrey.svg)](BENCHMARKS.md#memory-footprint-1)

crates/clawhdf5-accel/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-accel"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "SIMD-accelerated operations for rustyhdf5"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-agent/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-agent"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "HDF5-backed persistent memory store for on-device AI agents"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-android/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-android"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Android JNI bridge for edgehdf5-memory HDF5 backend"
 license = "MIT"
 

crates/clawhdf5-ann/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-ann"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "HNSW approximate nearest neighbor index stored as HDF5"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-bench/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-bench"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Benchmark harnesses for clawhdf5-agent (Track 8)"
 license = "MIT"
 

crates/clawhdf5-cli/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-cli"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 license = "MIT"
 description = "CLI for clawhdf5 agent memory — create, save, search, recall, stats"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-derive/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-derive"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Derive macros for rustyhdf5 HDF5 traits"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-filters/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-filters"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Filter and compression pipeline for clawhdf5"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-format/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-format"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Pure-Rust HDF5 binary format parsing and writing — no C dependencies"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-gpu/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-gpu"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "GPU-accelerated vector operations for rustyhdf5 using wgpu compute shaders"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-io/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-io"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "I/O abstraction layer for rustyhdf5"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-migrate/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-migrate"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "CLI to migrate SQLite agent memory databases to HDF5 format"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-napi/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-napi"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Node.js native addon (napi-rs) exposing clawhdf5-agent to TypeScript/JavaScript"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-netcdf4/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-netcdf4"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "NetCDF-4 read support built on rustyhdf5 — pure Rust, no C dependencies"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5-py/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5-py"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Python bindings for rustyhdf5 — a pure-Rust HDF5 library"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/clawhdf5/Cargo.toml

@@ -2,6 +2,7 @@
 name = "clawhdf5"
 version = "2.7.0"
 edition = "2024"
+rust-version.workspace = true
 description = "Pure-Rust HDF5 reader/writer — no C dependencies"
 license = "MIT"
 repository = "https://git.redclaw.dev/quantumclaw/clawhdf5"

crates/libaec-sys/Cargo.toml

@@ -2,6 +2,7 @@
 name = "libaec-sys"
 version = "0.1.0"
 edition = "2024"
+rust-version.workspace = true
 links = "aec"
 
 [build-dependencies]

scripts/ci-test.sh

@@ -106,6 +106,21 @@ no_c_in_default_build() {
 }
 run_step "no C in the default build (core crates)" no_c_in_default_build
 
+# The workspace declares a minimum Rust version (rust-version in Cargo.toml);
+# check that it really builds there, so the README badge and the manifests
+# cannot drift from the truth. Separate target dir: a different toolchain
+# would otherwise invalidate the main build.
+msrv_check() {
+    local msrv
+    msrv=$(sed -n 's/^rust-version = "\(.*\)"/\1/p' "$SCRIPT_DIR/../Cargo.toml")
+    [ -n "$msrv" ] || { echo "no rust-version in Cargo.toml"; return 1; }
+    rustup toolchain install "$msrv" --profile minimal >/dev/null || return 1
+    echo "checking with Rust $msrv"
+    CARGO_TARGET_DIR="$SCRIPT_DIR/../target/msrv" cargo "+$msrv" check \
+        --workspace --exclude clawhdf5-py --all-targets
+}
+run_step "MSRV check" msrv_check
+
 # 4. Tests (exclude clawhdf5-py)
 run_step "cargo test" cargo test \
     --workspace \