From f54203521322a88f8b2ca336c0730ed4b2d4f1b7 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 15:38:44 +0000
Subject: [PATCH 1/6] fix(deps): update aws-smithy-json to 0.62.7

Cargo.lock: aws-smithy-json moves from 0.62.3 to 0.62.7. Versions up to
0.62.6 recurse without a depth limit while skipping an unknown key, so a
deeply nested document can exhaust the stack (CVE-2026-18140,
GHSA-8ffr-xgwf-xj56). In this workspace only the AWS SDK clients behind
extenddb-backup-store (aws-config, aws-sdk-s3, aws-sdk-sso,
aws-sdk-ssooidc, aws-sdk-sts) use the crate, to parse the responses of
the S3, STS and SSO endpoints the operator configures.

0.62.7 requires aws-smithy-runtime-api 1.12.3 or newer, so the lock also
moves aws-smithy-runtime-api from 1.11.3 to 1.12.3, aws-smithy-types
from 1.4.3 to 1.4.9 and aws-smithy-async from 1.2.11 to 1.2.14, and adds
aws-smithy-runtime-api-macros 1.0.0 and aws-smithy-schema 0.1.0. Each is
the lowest version the new requirements accept. No other package moves,
and each aws-smithy crate resolves to one version.

The six crates declare rustc 1.91.1 as their minimum, above the
workspace rust-version of 1.88, so a 1.88 toolchain refuses to build
extenddb-backup-store with this lock. The release images build only the
extenddb binary, which does not depend on extenddb-backup-store, so they
are unaffected.
---
 Cargo.lock | 41 +++++++++++++++++++++++++++++++++--------
 1 file changed, 33 insertions(+), 8 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c033bcd24..4ab155aad 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -445,9 +445,9 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-async"
-version = "1.2.11"
+version = "1.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "52eec3db979d18cb807fc1070961cc51d87d069abe9ab57917769687368a8c6c"
+checksum = "2ffcaf626bdda484571968400c326a244598634dc75fd451325a54ad1a59acfc"
 dependencies = [
  "futures-util",
  "pin-project-lite",
@@ -534,10 +534,12 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-json"
-version = "0.62.3"
+version = "0.62.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3cb96aa208d62ee94104645f7b2ecaf77bf27edf161590b6224bfbac2832f979"
+checksum = "701a947f4797e52a911e114a898667c746c39feea467bbd1abd7b3721f702ffa"
 dependencies = [
+ "aws-smithy-runtime-api",
+ "aws-smithy-schema",
  "aws-smithy-types",
 ]
 
@@ -587,11 +589,12 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-runtime-api"
-version = "1.11.3"
+version = "1.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49952c52f7eebb72ce2a754d3866cc0f87b97d2a46146b79f80f3a93fb2b3716"
+checksum = "9db177daa6ba8afb9ee1aefcf548c907abcf52065e394ee11a92780057fe0e8c"
 dependencies = [
  "aws-smithy-async",
+ "aws-smithy-runtime-api-macros",
  "aws-smithy-types",
  "bytes",
  "http 0.2.12",
@@ -602,11 +605,33 @@ dependencies = [
  "zeroize",
 ]
 
+[[package]]
+name = "aws-smithy-runtime-api-macros"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d7396fd9500589e62e460e987ecb671bad374934e55ec3b5f498cc7a8a8a7b7"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
+[[package]]
+name = "aws-smithy-schema"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7442cb268338f0eb8278140a107c046756aa01093d8ef5e99628d34ae09c94f5"
+dependencies = [
+ "aws-smithy-runtime-api",
+ "aws-smithy-types",
+ "http 1.4.0",
+]
+
 [[package]]
 name = "aws-smithy-types"
-version = "1.4.3"
+version = "1.4.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3b3a26048eeab0ddeba4b4f9d51654c79af8c3b32357dc5f336cee85ab331c33"
+checksum = "53f93074121a1be41317b9aa607143ae17900631f7f59a99f2b905d519d6783b"
 dependencies = [
  "base64-simd",
  "bytes",

From 619b25af9c06403509db2bc05049cdf731e0fe38 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 16:07:13 +0000
Subject: [PATCH 2/6] build: raise the minimum Rust version to 1.91.1

aws-smithy-json 0.62.7, the first release with the fix for
CVE-2026-18140, and the five aws-smithy crates it needs declare rustc
1.91.1 as their minimum. The workspace minimum was 1.88.

Cargo.toml sets rust-version to 1.91.1. The comment on the aws-sdk pins
now says that each pinned version declares a minimum at or below the
workspace rust-version, and .cargo/config.toml names 1.91.1 for the
resolver fallback.

The comments next to the two compare-exchange loops that stand in for
fetch_update now name 1.91.1: the replacement, try_update, is still
unstable there.

clippy reads the minimum from rust-version, and from 1.91 it asks for
Duration::from_mins where a value is a whole number of minutes. The
three cases are in extenddb-cache: the default TTL in swr.rs and two
lines of tests.rs now use Duration::from_mins(1).
---
 .cargo/config.toml                                |  4 ++--
 Cargo.toml                                        | 15 +++++++--------
 crates/cache/src/swr.rs                           |  2 +-
 crates/cache/src/tests.rs                         |  4 ++--
 .../storage-cassandra/src/migrations/backend.rs   |  2 +-
 crates/storage-mongodb/src/migrations/guarded.rs  |  2 +-
 6 files changed, 14 insertions(+), 15 deletions(-)

diff --git a/.cargo/config.toml b/.cargo/config.toml
index cfc36d196..4cab86c4f 100644
--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -3,7 +3,7 @@
 
 [resolver]
 # Prefer dependency versions whose declared rust-version fits the workspace
-# rust-version (1.88, tested in CI), so `cargo update` on a newer toolchain
-# does not pull in crates that no longer build on 1.88. Only applies when a
+# rust-version (1.91.1, tested in CI), so `cargo update` on a newer toolchain
+# does not pull in crates that no longer build on 1.91.1. Only applies when a
 # newer version would be incompatible; everything else updates as usual.
 incompatible-rust-versions = "fallback"
diff --git a/Cargo.toml b/Cargo.toml
index 97e64e9e0..5478d866e 100755
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,7 @@ members = [
 [workspace.package]
 version = "0.1.14"
 edition = "2024"
-rust-version = "1.88"
+rust-version = "1.91.1"
 license = "Apache-2.0"
 
 [workspace.dependencies]
@@ -89,14 +89,13 @@ bson = "2.13"
 dashmap = "6"
 
 # Backup store
-# Exact pins: the aws-sdk crates release in lockstep, and these are the newest
-# versions whose declared minimum supported rustc fits the workspace
-# rust-version (1.88); later releases require a newer compiler. Their
-# transitive aws-* and aws-smithy-* crates are held in Cargo.lock at the
-# newest versions that build on 1.88 (set with
-# `cargo +1.88.0 update <crate>@<version> --precise <older>`). The resolver
+# Exact pins: the aws-sdk crates release in lockstep, and each of these
+# versions declares a minimum supported rustc at or below the workspace
+# rust-version (1.91.1). Their transitive aws-* and aws-smithy-* crates are
+# held in Cargo.lock at versions that build on 1.91.1 (set with
+# `cargo +1.91.1 update <crate>@<version> --precise <older>`). The resolver
 # fallback in .cargo/config.toml keeps a plain `cargo update` from moving
-# them past that, and the 1.88 leg of .github/workflows/test.yml fails if
+# them past that, and the 1.91.1 leg of .github/workflows/test.yml fails if
 # they drift. The feature set is that of tests/rust/Cargo.toml plus `sso` on
 # aws-config, so a server whose credentials come from an SSO profile
 # (`sso_session` in the shared config) can reach the backup bucket.
diff --git a/crates/cache/src/swr.rs b/crates/cache/src/swr.rs
index 6331f39e1..5b2e553d9 100644
--- a/crates/cache/src/swr.rs
+++ b/crates/cache/src/swr.rs
@@ -37,7 +37,7 @@ pub struct SwrCacheConfig {
 impl Default for SwrCacheConfig {
     fn default() -> Self {
         Self {
-            ttl: Duration::from_secs(60),
+            ttl: Duration::from_mins(1),
             soft_ttl: Duration::from_secs(30),
             negative_ttl: Duration::from_secs(5),
             max_entries: 10_000,
diff --git a/crates/cache/src/tests.rs b/crates/cache/src/tests.rs
index 3315e025f..f1e55986b 100644
--- a/crates/cache/src/tests.rs
+++ b/crates/cache/src/tests.rs
@@ -365,7 +365,7 @@ async fn refresh_failure_does_not_evict_stale_entry() {
 async fn lru_eviction_caps_size_at_max_entries() {
     let (loader, _) = CountingLoader::new();
     let config = SwrCacheConfig {
-        ttl: Duration::from_secs(60),
+        ttl: Duration::from_mins(1),
         soft_ttl: Duration::from_secs(30),
         negative_ttl: Duration::from_secs(5),
         max_entries: 4,
@@ -402,7 +402,7 @@ async fn invalidate_all_clears_every_entry() {
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
 async fn config_default_has_expected_values() {
     let cfg = SwrCacheConfig::default();
-    assert_eq!(cfg.ttl, Duration::from_secs(60));
+    assert_eq!(cfg.ttl, Duration::from_mins(1));
     assert_eq!(cfg.soft_ttl, Duration::from_secs(30));
     assert_eq!(cfg.negative_ttl, Duration::from_secs(5));
     assert_eq!(cfg.max_entries, 10_000);
diff --git a/crates/storage-cassandra/src/migrations/backend.rs b/crates/storage-cassandra/src/migrations/backend.rs
index 0d59590b5..336604203 100644
--- a/crates/storage-cassandra/src/migrations/backend.rs
+++ b/crates/storage-cassandra/src/migrations/backend.rs
@@ -212,7 +212,7 @@ pub(crate) fn stopped(left: Option<&std::sync::atomic::AtomicUsize>) -> bool {
         return false;
     };
     // A compare-exchange loop: `fetch_update` is deprecated on current
-    // stable and its replacement does not exist on 1.88.
+    // stable and its replacement does not exist on 1.91.1.
     let mut n = left.load(Ordering::SeqCst);
     loop {
         let Some(next) = n.checked_sub(1) else {
diff --git a/crates/storage-mongodb/src/migrations/guarded.rs b/crates/storage-mongodb/src/migrations/guarded.rs
index 67cf341d7..d4a937828 100644
--- a/crates/storage-mongodb/src/migrations/guarded.rs
+++ b/crates/storage-mongodb/src/migrations/guarded.rs
@@ -45,7 +45,7 @@ pub(crate) struct LeasedManagementStore {
 pub(crate) fn stopped(left: Option<&std::sync::atomic::AtomicUsize>) -> bool {
     use std::sync::atomic::Ordering;
     // A compare-exchange loop: `fetch_update` is deprecated on current
-    // stable and its replacement does not exist on 1.88.
+    // stable and its replacement does not exist on 1.91.1.
     let Some(left) = left else {
         return false;
     };

From f8d64529b63f5f6932b5f421f924fd9f75a61593 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 16:07:13 +0000
Subject: [PATCH 3/6] ci: run the minimum version leg of test.yml on Rust
 1.91.1

The workspace rust-version is 1.91.1, so the leg that checks the
minimum moves from 1.88.0 to 1.91.1.
---
 .github/workflows/test.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ef1b68230..b3c5100f2 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -27,7 +27,7 @@ jobs:
     timeout-minutes: 15
     strategy:
       matrix:
-        toolchain: [stable, "1.88.0"]
+        toolchain: [stable, "1.91.1"]
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
       - uses: dtolnay/rust-toolchain@683b588c487a69d01f6c6ddf40f036ff682cc2c8 # master

From 2f524d4cbff4a617a47a889a72c467259ad2b6c0 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 16:07:13 +0000
Subject: [PATCH 4/6] docs: name Rust 1.91.1 as the minimum version

README.md, CONTRIBUTING.md, the getting started page, the quick start
and install manuals and the backup design name 1.91.1, the workspace
rust-version.
---
 CONTRIBUTING.md                           | 2 +-
 README.md                                 | 2 +-
 docs/design/15-backup-restore.md          | 2 +-
 docs/getting-started.md                   | 2 +-
 docs/manuals/04-quickstart-setup-guide.md | 2 +-
 docs/manuals/08-install-linux.md          | 2 +-
 docs/manuals/09-install-macos.md          | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c6b34b7f3..77215a301 100755
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -6,7 +6,7 @@ Thank you for your interest in contributing to ExtendDB!
 
 ### Prerequisites
 
-- Rust 1.88+ (stable)
+- Rust 1.91.1+ (stable)
 - PostgreSQL 14+
 - Python 3.10+ (for integration tests)
 
diff --git a/README.md b/README.md
index 9f5e9f664..823d79294 100755
--- a/README.md
+++ b/README.md
@@ -53,7 +53,7 @@ scripts/install-macos.sh   # macOS
 
 ## Prerequisites
 
-- Rust 1.88+ (`rustup update`)
+- Rust 1.91.1+ (`rustup update`)
 - Python 3.10+ (for test suites and documentation)
 - A storage backend:
   - PostgreSQL 14+ (see `docs/local-postgres-setup.md`)
diff --git a/docs/design/15-backup-restore.md b/docs/design/15-backup-restore.md
index 06c13ece0..551eba3a7 100644
--- a/docs/design/15-backup-restore.md
+++ b/docs/design/15-backup-restore.md
@@ -482,7 +482,7 @@ Phase 3, later (v1.x):
 
 - Backups are asynchronous where the current implementation is synchronous; clients that assumed AVAILABLE on return must poll, which is what they do against DynamoDB.
 - Long snapshot transactions on PostgreSQL delay vacuum for the backup duration; MongoDB snapshot windows bound backup duration by server configuration.
-- A new dependency on the AWS S3 SDK (its lock entries pinned to the versions that build on the workspace's 1.88 toolchain, which also holds `crc` at 3.3.0 for the server; the licence notices change when PR 7 links the crate into the server) and an S3 mock in CI.
+- A new dependency on the AWS S3 SDK (its lock entries pinned to the versions that build on the workspace's 1.91.1 toolchain, which also holds `crc` at 3.3.0 for the server; the licence notices change when PR 7 links the crate into the server) and an S3 mock in CI.
 - A restore from an S3 store spools the whole compressed backup to local disk before loading any of it.
 - One core at full utilization for the duration of a backup on compression; `max_concurrent_jobs` and `spawn_blocking` keep it off the request threads but do not make it free on a 2-vCPU host.
 - Two code paths for one release while legacy backups remain readable.
diff --git a/docs/getting-started.md b/docs/getting-started.md
index c1c27db98..6657786d0 100755
--- a/docs/getting-started.md
+++ b/docs/getting-started.md
@@ -41,7 +41,7 @@ See [Local Development with Docker Compose](local-dev-docker-compose.md).
   - SQLite (embedded; nothing to install)
   - MongoDB 7.0+ with replica set (see `docs/local-mongodb-setup.md`)
   - Cassandra 4.1+ running locally (see `docs/cassandra-setup.md`)
-- Rust toolchain (1.88+)
+- Rust toolchain (1.91.1+)
 - AWS CLI v2 (for testing)
 - Python 3.10+ with virtual environment (see [Python Environment Setup](../README.md#python-environment-setup) in the README)
 
diff --git a/docs/manuals/04-quickstart-setup-guide.md b/docs/manuals/04-quickstart-setup-guide.md
index 08333d9dd..96625230a 100755
--- a/docs/manuals/04-quickstart-setup-guide.md
+++ b/docs/manuals/04-quickstart-setup-guide.md
@@ -9,7 +9,7 @@ This section gets you from zero to a working extenddb instance as fast as possib
 ### Prerequisites
 
 - PostgreSQL 14+ running locally
-- Rust toolchain 1.88+
+- Rust toolchain 1.91.1+
 - AWS CLI v2
 
 ### Steps
diff --git a/docs/manuals/08-install-linux.md b/docs/manuals/08-install-linux.md
index 2b868522e..0267854a4 100755
--- a/docs/manuals/08-install-linux.md
+++ b/docs/manuals/08-install-linux.md
@@ -26,7 +26,7 @@ If you prefer to run each step yourself, follow the sections below.
 
 ## Prerequisites
 
-- Rust 1.88+ (`rustup update`)
+- Rust 1.91.1+ (`rustup update`)
 - PostgreSQL 14+
 - Python 3.10+ (for test suites)
 - AWS CLI v2 (for testing)
diff --git a/docs/manuals/09-install-macos.md b/docs/manuals/09-install-macos.md
index b1ca6de2d..23a1217d2 100755
--- a/docs/manuals/09-install-macos.md
+++ b/docs/manuals/09-install-macos.md
@@ -26,7 +26,7 @@ If you prefer to run each step yourself, follow the sections below.
 
 ## Prerequisites
 
-- Rust 1.88+ (`rustup update`)
+- Rust 1.91.1+ (`rustup update`)
 - PostgreSQL 14+ via Homebrew (`brew install postgresql@17`)
 - Python 3.10+ (for test suites)
 - AWS CLI v2 (for testing)

From 27c1dfd6086e032532cbb1fb4d6dc49c299e28f1 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 16:07:13 +0000
Subject: [PATCH 5/6] build: build the images on Rust 1.91.1

The four Dockerfiles build on rust:1.91.1-bookworm, pinned by digest.
Cargo refuses to build a package on a compiler older than its
rust-version, so the 1.88 build stage would fail on every image.
---
 Dockerfile           | 2 +-
 Dockerfile.cassandra | 2 +-
 Dockerfile.dev       | 2 +-
 Dockerfile.mongodb   | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index e660f3d7c..dcf45ceda 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,7 +2,7 @@
 
 # The runtime base is explicitly approved for this public OSS distribution.
 # Keep both references digest-pinned and update them only through reviewed CRs.
-FROM public.ecr.aws/docker/library/rust:1.88-bookworm@sha256:af306cfa71d987911a781c37b59d7d67d934f49684058f96cf72079c3626bfe0 AS build
+FROM public.ecr.aws/docker/library/rust:1.91.1-bookworm@sha256:c1e5f19e773b7878c3f7a805dd00a495e747acbdc76fb2337a4ebf0418896b33 AS build
 ARG VCS_REF
 ARG BUILD_DATE
 WORKDIR /src
diff --git a/Dockerfile.cassandra b/Dockerfile.cassandra
index 9652feabf..2cfbb5f55 100644
--- a/Dockerfile.cassandra
+++ b/Dockerfile.cassandra
@@ -4,7 +4,7 @@
 # external service: use an Apache Cassandra 4.1+ cluster you operate, or the
 # optional docker-compose.cassandra.yml reference stack for local development.
 
-FROM public.ecr.aws/docker/library/rust:1.88-bookworm@sha256:af306cfa71d987911a781c37b59d7d67d934f49684058f96cf72079c3626bfe0 AS build
+FROM public.ecr.aws/docker/library/rust:1.91.1-bookworm@sha256:c1e5f19e773b7878c3f7a805dd00a495e747acbdc76fb2337a4ebf0418896b33 AS build
 ARG VCS_REF
 ARG BUILD_DATE
 WORKDIR /src
diff --git a/Dockerfile.dev b/Dockerfile.dev
index 57f41f117..2a3ed0064 100644
--- a/Dockerfile.dev
+++ b/Dockerfile.dev
@@ -14,7 +14,7 @@
 #     production binaries keep readable panic backtraces.
 #   * distroless runtime: no shell, no package manager, no setuid binaries.
 
-FROM public.ecr.aws/docker/library/rust:1.88-bookworm@sha256:af306cfa71d987911a781c37b59d7d67d934f49684058f96cf72079c3626bfe0 AS build
+FROM public.ecr.aws/docker/library/rust:1.91.1-bookworm@sha256:c1e5f19e773b7878c3f7a805dd00a495e747acbdc76fb2337a4ebf0418896b33 AS build
 ARG VCS_REF
 ARG BUILD_DATE
 WORKDIR /src
diff --git a/Dockerfile.mongodb b/Dockerfile.mongodb
index 67b4f2ed1..205ee79d9 100644
--- a/Dockerfile.mongodb
+++ b/Dockerfile.mongodb
@@ -4,7 +4,7 @@
 # external service: use MongoDB Atlas, a managed replica set, or the optional
 # docker-compose.mongodb.yml reference stack.
 
-FROM public.ecr.aws/docker/library/rust:1.88-bookworm@sha256:af306cfa71d987911a781c37b59d7d67d934f49684058f96cf72079c3626bfe0 AS build
+FROM public.ecr.aws/docker/library/rust:1.91.1-bookworm@sha256:c1e5f19e773b7878c3f7a805dd00a495e747acbdc76fb2337a4ebf0418896b33 AS build
 ARG VCS_REF
 ARG BUILD_DATE
 WORKDIR /src

From 618f503e92f5b10375cdba57213a5c7d22f5e295 Mon Sep 17 00:00:00 2001
From: Lee <29015211+LeeroyHannigan@users.noreply.github.com>
Date: Thu, 5 Nov 2026 16:07:13 +0000
Subject: [PATCH 6/6] docs: name Rust 1.91.1 in the contributor and setup notes

AGENTS.md and the setup references under .agents/skills name 1.91.1,
the workspace rust-version.
---
 .../extenddb/references/setup/02-dependency-checks.md  | 10 +++++-----
 .../skills/extenddb/references/setup/03-build-stage.md |  2 +-
 AGENTS.md                                              |  6 +++---
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/.agents/skills/extenddb/references/setup/02-dependency-checks.md b/.agents/skills/extenddb/references/setup/02-dependency-checks.md
index 884ccfa88..54695616d 100644
--- a/.agents/skills/extenddb/references/setup/02-dependency-checks.md
+++ b/.agents/skills/extenddb/references/setup/02-dependency-checks.md
@@ -8,7 +8,7 @@ This file lists the dependency checks the `extenddb-setup` skill runs before pro
 
 | Dependency | Check command | Minimum version | Rationale |
 |---|---|---|---|
-| Rust toolchain | `cargo --version` and `rustc --version` | 1.88 | extenddb is a Rust workspace; older toolchains fail `cargo build --release`. |
+| Rust toolchain | `cargo --version` and `rustc --version` | 1.91.1 | extenddb is a Rust workspace; older toolchains fail `cargo build --release`. |
 | PostgreSQL client | `psql --version` | 14 | extenddb speaks the Postgres protocol at init and runtime; older clients may lack required features. |
 | PostgreSQL server readiness | `pg_isready` | n/a (server-side check) | Confirms the server is reachable before `extenddb init`. |
 | Python 3 | `python3 --version` | 3.10 | Required by the sample apps and the docs build pipeline. |
@@ -29,7 +29,7 @@ If `which cargo` exits nonzero, Rust is not installed. Install:
 - Linux (Fedora/RHEL): `curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh`
 - macOS: `brew install rustup-init && rustup-init`
 
-If Rust is installed but `rustc --version` reports older than 1.88:
+If Rust is installed but `rustc --version` reports older than 1.91.1:
 
 ```bash
 rustup update
@@ -84,7 +84,7 @@ If `python3 --version` reports older than 3.10, upgrade via the same package man
 
 ## Version parsing
 
-`rustc --version` prints `rustc 1.88.0 (abcdef0 2025-01-01)`. Extract the version field with `awk`:
+`rustc --version` prints `rustc 1.91.1 (abcdef0 2025-01-01)`. Extract the version field with `awk`:
 
 ```bash
 rustc --version | awk '{print $2}'
@@ -96,11 +96,11 @@ rustc --version | awk '{print $2}'
 psql --version | awk '{print $3}'
 ```
 
-Compare the extracted version against the minimum (1.88 for Rust, 14 for Postgres) by splitting on `.` and comparing numerically. For skill-level checks, a string prefix comparison (`[[ "$PG_VER" < "14" ]]`) is adequate because major versions are single or double digits.
+Compare the extracted version against the minimum (1.91.1 for Rust, 14 for Postgres) by splitting on `.` and comparing numerically. For skill-level checks, a string prefix comparison (`[[ "$PG_VER" < "14" ]]`) is adequate because major versions are single or double digits.
 
 ## Rust version upgrade path
 
-If Rust is installed via rustup and `rustc --version` reports older than 1.88, the fix is:
+If Rust is installed via rustup and `rustc --version` reports older than 1.91.1, the fix is:
 
 ```bash
 rustup update
diff --git a/.agents/skills/extenddb/references/setup/03-build-stage.md b/.agents/skills/extenddb/references/setup/03-build-stage.md
index 8204129fc..90833bb87 100644
--- a/.agents/skills/extenddb/references/setup/03-build-stage.md
+++ b/.agents/skills/extenddb/references/setup/03-build-stage.md
@@ -59,4 +59,4 @@ This should print the extenddb version string. If it does not, the build failed
 cargo build --release --verbose
 ```
 
-Common causes of silent build failure are a missing system library (for example, `libpq-dev` or `openssl-dev` on Linux), a Rust toolchain older than 1.88, or a disk full condition under `target/`. The verbose output names the failing crate and the missing dependency.
+Common causes of silent build failure are a missing system library (for example, `libpq-dev` or `openssl-dev` on Linux), a Rust toolchain older than 1.91.1, or a disk full condition under `target/`. The verbose output names the failing crate and the missing dependency.
diff --git a/AGENTS.md b/AGENTS.md
index 83c7ac296..992e887a2 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -9,7 +9,7 @@ License. ExtendDB is a clean-room implementation of the DynamoDB wire protocol,
 by AWS engineers. It is not a fork of DynamoDB and contains no DynamoDB source code. ExtendDB speaks the DynamoDB wire
 protocol: any AWS SDK, CLI, or tool that works with DynamoDB works with ExtendDB, unchanged.
 
-- **Language:** Rust (edition 2024, MSRV 1.88+)
+- **Language:** Rust (edition 2024, MSRV 1.91.1+)
 - **Storage backends:** PostgreSQL 14+ (default), SQLite (bundled, no server or client install required; feature flag `sqlite`, also `sqlite-memory` for dev and CI), MongoDB 7.0+ (feature flag `mongodb`), Cassandra 4.1+ (experimental; feature flag `cassandra`). One backend per binary, selected by mutually exclusive Cargo features.
 - **Architecture:** Async (tokio), trait-based storage abstraction
 - **Authentication:** Mandatory SigV4 with built-in IAM (users, groups, roles, policies)
@@ -97,7 +97,7 @@ extenddb (bin)
 
 ### Prerequisites
 
-- Rust 1.88+ (`rustup update`)
+- Rust 1.91.1+ (`rustup update`)
 - Storage backend (one of):
   - PostgreSQL 14+ running locally (see `docs/local-postgres-setup.md`)
   - SQLite (embedded; nothing to install)
@@ -415,7 +415,7 @@ python3 docs/build-docs.py
 ## Code Style and Conventions
 
 - **Rust edition:** 2024
-- **MSRV:** 1.88
+- **MSRV:** 1.91.1
 - **Async:** tokio, no `#[async_trait]` (use RPITIT)
 - **Error handling:** `thiserror` for library errors, `anyhow` for application errors
 - **Serialization:** `serde` + `serde_json`