diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index cf2af309..7b5c636f 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -29,3 +29,10 @@ updates:
     cooldown:
       default-days: 7
       semver-major-days: 14
+  - package-ecosystem: rust-toolchain
+    directory: /
+    labels:
+      - dependencies
+      - rust-toolchain
+    schedule:
+      interval: weekly
diff --git a/AGENTS.md b/AGENTS.md
index 4f2b6bf6..16f660b3 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -367,3 +367,12 @@ The following tooling is available in this environment:
 
 These practices help maintain a high-quality codebase and facilitate
 collaboration.
+
+## Fast development builds
+
+`make dev-build` and `make dev-test` compile with the opt-in Cranelift
+backend and the mold linker configured in `tools/dev-fast/config.toml`.
+They require a nightly toolchain and, on Linux, a `mold` binary on the
+`PATH`. The fragment is passed explicitly with `--config`, so release,
+coverage, and verification builds are unaffected; never copy its contents
+into `.cargo/config.toml`, which Cargo applies to every build.
diff --git a/Makefile b/Makefile
index e7cfb6c2..c67e1666 100644
--- a/Makefile
+++ b/Makefile
@@ -132,3 +132,14 @@ run-verus: ## Run the configured Verus proof entry point
 help: ## Show available targets
 	@grep -E '^[a-zA-Z_-]+:.*?##' $(MAKEFILE_LIST) | \
 	awk 'BEGIN {FS=":"; printf "Available targets:\n"} {printf "  %-20s %s\n", $$1, $$2}'
+
+# Opt-in accelerated debug builds (Cranelift + mold); requires a nightly
+# toolchain. See AGENTS.md and tools/dev-fast/config.toml.
+DEV_FAST_CONFIG ?= tools/dev-fast/config.toml
+
+.PHONY: dev-build dev-test
+dev-build: ## Build debug binaries with Cranelift and mold
+	cargo --config "$(DEV_FAST_CONFIG)" build
+
+dev-test: ## Run tests with Cranelift and mold
+	cargo --config "$(DEV_FAST_CONFIG)" test
diff --git a/tools/dev-fast/config.toml b/tools/dev-fast/config.toml
new file mode 100644
index 00000000..01e7f899
--- /dev/null
+++ b/tools/dev-fast/config.toml
@@ -0,0 +1,31 @@
+# Canonical opt-in Cargo configuration fragment for accelerated local debug
+# builds.
+#
+# This configuration is deliberately kept out of `.cargo/config.toml`.
+# Cargo auto-discovers that path, so anything placed there applies to
+# release packaging, coverage, and verification builds, which must keep
+# the supported LLVM backend and platform linker. In a consuming
+# repository this fragment lives at `tools/dev-fast/config.toml` and is
+# passed explicitly with `cargo --config tools/dev-fast/config.toml ...`
+# from `make dev-build` and `make dev-test`.
+#
+# Repositories that set repository-wide `rustflags` in `.cargo/config.toml`
+# must restate them in the target table below. Cargo joins the rustflags of
+# every matching `[target.*]` entry (target-triple and `cfg` tables alike),
+# but the joined target rustflags take precedence over `[build].rustflags`
+# rather than merging with it.
+
+[unstable]
+codegen-backend = true
+
+# Cranelift trades runtime performance for compile speed, so it applies to
+# the dev profile only. The `make dev-*` targets never build release
+# artefacts.
+[profile.dev]
+codegen-backend = "cranelift"
+
+# mold ships for Linux only, so the flag is gated behind a target `cfg`. On
+# macOS and Windows the table simply does not apply and the platform default
+# linker is used.
+[target.'cfg(target_os = "linux")']
+rustflags = ["-Clink-arg=-fuse-ld=mold"]
diff --git a/typos.local.toml b/typos.local.toml
index 7d279684..1f55352e 100644
--- a/typos.local.toml
+++ b/typos.local.toml
@@ -10,6 +10,13 @@ accepted = []
 
 [patterns]
 ignore = [
+  # "mold" names the linker (https://github.com/rui314/mold) in these
+  # contexts only; the mould correction stays active elsewhere.
+  "-fuse-ld=mold",
+  "mold linker",
+  "Cranelift \\+ mold",
+  "Cranelift and mold",
+  "`mold`",
   "\\ \\ \\ \\ PoolServerBehavior,",
   "\\ \\ \\ \\ \\ \\ CARGO_TERM_COLOR:\\ always",
   "\\ \\ \\ \\ \\ \\ \\ Self::start_with_behavior\\(PoolServerBehavior::Ech",
diff --git a/typos.toml b/typos.toml
index a55d8c3b..ae4c097b 100644
--- a/typos.toml
+++ b/typos.toml
@@ -31,6 +31,9 @@ extend-exclude = [
 locale = "en-gb"
 extend-ignore-re = [
     "(?s)```.*?```",
+    "-fuse-ld=mold",
+    "Cranelift \\+ mold",
+    "Cranelift and mold",
     "\\ \\ \\ \\ PoolServerBehavior,",
     "\\ \\ \\ \\ \\ \\ CARGO_TERM_COLOR:\\ always",
     "\\ \\ \\ \\ \\ \\ \\ Self::start_with_behavior\\(PoolServerBehavior::Ech",
@@ -50,10 +53,12 @@ extend-ignore-re = [
     "\\brust-analyzer\\b",
     "\\|\\|\\ \"fragment\\ series\\ not\\ initialised\"\\.into\\(\\)\\)",
     "`[^`\\n]+`",
+    "`mold`",
     "ask\\ items\\ with\\ a\\ GitHub\\ Flavored",
     "e\\.behavior\\ ==\\ PoolServerBehavior::MalformedFirstResponse",
     "ior\\(behavior:\\ PoolServerBehavior\\)\\ \\->\\ std::io::Result<Sel",
     "lTestServer::start_with_behavior\\(PoolServerBehavior::Mal",
+    "mold linker",
     "pub\\ async\\ fn\\ start_with_behavior\\(behavior:\\ PoolServerBeh",
     "pub\\ enum\\ PoolServerBehavior\\ \\{",
     "st\\(start_paused\\ =\\ true,\\ flavor\\ =\\ \"current_thread\"\\)\\]",