diff --git a/CHANGELOG.md b/CHANGELOG.md
index e437f17..5f8dc5b 100644
--- a/CHANGELOG.md
+++ b/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
diff --git a/CLAUDE.md b/CLAUDE.md
index 6b9fa24..cb10c9e 100644
--- a/CLAUDE.md
+++ b/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
diff --git a/Cargo.toml b/Cargo.toml
index 61c47f8..2e1f6fe 100644
--- a/Cargo.toml
+++ b/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"
 
diff --git a/README.md b/README.md
index cf93565..58799af 100644
--- a/README.md
+++ b/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)
diff --git a/crates/clawhdf5-accel/Cargo.toml b/crates/clawhdf5-accel/Cargo.toml
index b24d81d..e59a2ba 100644
--- a/crates/clawhdf5-accel/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-agent/Cargo.toml b/crates/clawhdf5-agent/Cargo.toml
index a7e6796..b8d79ee 100644
--- a/crates/clawhdf5-agent/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-android/Cargo.toml b/crates/clawhdf5-android/Cargo.toml
index 2ad609c..38dd2a0 100644
--- a/crates/clawhdf5-android/Cargo.toml
+++ b/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"
 
diff --git a/crates/clawhdf5-ann/Cargo.toml b/crates/clawhdf5-ann/Cargo.toml
index 6a5469f..be1b37f 100644
--- a/crates/clawhdf5-ann/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-bench/Cargo.toml b/crates/clawhdf5-bench/Cargo.toml
index 879e921..5ac6350 100644
--- a/crates/clawhdf5-bench/Cargo.toml
+++ b/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"
 
diff --git a/crates/clawhdf5-cli/Cargo.toml b/crates/clawhdf5-cli/Cargo.toml
index c622e6e..f8e7a15 100644
--- a/crates/clawhdf5-cli/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-derive/Cargo.toml b/crates/clawhdf5-derive/Cargo.toml
index e15a46f..c5ca5f1 100644
--- a/crates/clawhdf5-derive/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-filters/Cargo.toml b/crates/clawhdf5-filters/Cargo.toml
index 07fdeff..dd6060a 100644
--- a/crates/clawhdf5-filters/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-format/Cargo.toml b/crates/clawhdf5-format/Cargo.toml
index fe38392..8567a7f 100644
--- a/crates/clawhdf5-format/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-gpu/Cargo.toml b/crates/clawhdf5-gpu/Cargo.toml
index 3ac02aa..d24aba4 100644
--- a/crates/clawhdf5-gpu/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-io/Cargo.toml b/crates/clawhdf5-io/Cargo.toml
index f339c71..53d82f1 100644
--- a/crates/clawhdf5-io/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-migrate/Cargo.toml b/crates/clawhdf5-migrate/Cargo.toml
index cf714fd..a518a22 100644
--- a/crates/clawhdf5-migrate/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-napi/Cargo.toml b/crates/clawhdf5-napi/Cargo.toml
index 28d8bda..c47403f 100644
--- a/crates/clawhdf5-napi/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-netcdf4/Cargo.toml b/crates/clawhdf5-netcdf4/Cargo.toml
index ad49148..6c38342 100644
--- a/crates/clawhdf5-netcdf4/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5-py/Cargo.toml b/crates/clawhdf5-py/Cargo.toml
index 8f3ea65..0d54a4f 100644
--- a/crates/clawhdf5-py/Cargo.toml
+++ b/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"
diff --git a/crates/clawhdf5/Cargo.toml b/crates/clawhdf5/Cargo.toml
index 40dbec2..2e2b4b4 100644
--- a/crates/clawhdf5/Cargo.toml
+++ b/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"
diff --git a/crates/libaec-sys/Cargo.toml b/crates/libaec-sys/Cargo.toml
index 788781a..75a7e8b 100644
--- a/crates/libaec-sys/Cargo.toml
+++ b/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]
diff --git a/scripts/ci-test.sh b/scripts/ci-test.sh
index 4df9e33..b52c88b 100755
--- a/scripts/ci-test.sh
+++ b/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 \