diff --git a/.github/dependabot.yml b/.github/dependabot.yml
index 9b3a19c..e57b900 100644
--- a/.github/dependabot.yml
+++ b/.github/dependabot.yml
@@ -28,3 +28,10 @@ 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 fdd2710..f5e5bc0 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -378,3 +378,12 @@ 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/Cargo.lock b/Cargo.lock
index 7b6e2e6..d62705f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,6 +2,312 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c982642fa9e8606056828ee9a8505737230110bb1099153c79efe865c59d12ba"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "camino"
+version = "1.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb1307f12aa967b5a58416e87b3653360e0fd614a016b6e970db08fecbb1b80d"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
+
+[[package]]
+name = "equivalent"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
+
+[[package]]
+name = "futures-core"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92d699e522242e69e3003b94ecc1f960f3a5e015aa7c5d7486e65ad01dd94f5e"
+
+[[package]]
+name = "futures-macro"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fb9654ba8355388abeb8dcb4fc62f511300867002afc858860463bdd9fe0c44"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.3",
+]
+
+[[package]]
+name = "futures-task"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd417de3d1d015fc3bfd2b1ea46dfc7bab72ef86f1cc7cc9c78e728b34a6d1fd"
+
+[[package]]
+name = "futures-timer"
+version = "3.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af43fadb8a98512d547e37b4e92e0ced13e205c061b87b4623eff01d918d6968"
+
+[[package]]
+name = "futures-util"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d50a92467f8ba5dd6e3ee5d4bd04d73ab2e4e1c44474a0674821dfce14b79bc"
+dependencies = [
+ "futures-core",
+ "futures-macro",
+ "futures-task",
+ "pin-project-lite",
+ "slab",
+]
+
+[[package]]
+name = "glob"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e4eba85ea1d0a966a983acd07deee566e67395d2d96b6fb39e62b5a833f1eb0b"
+
+[[package]]
+name = "hashbrown"
+version = "0.17.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed5909b6e89a2db4456e54cd5f673791d7eca6732202bbf2a9cc504fe2f9b84a"
+
+[[package]]
+name = "indexmap"
+version = "2.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d466e9454f08e4a911e14806c24e16fba1b4c121d1ea474396f396069cf949d9"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
+[[package]]
+name = "memchr"
+version = "2.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf8baf1c55e62ffcace7a9f06f4bd9cd3f0c4beb022d3b367256b91b87513d98"
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"
+
+[[package]]
+name = "proc-macro-crate"
+version = "3.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e67ba7e9b2b56446f1d419b1d807906278ffa1a658a8a5d8a39dcb1f5a78614f"
+dependencies = [
+ "toml_edit",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.107"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "985e7ec9bb745e6ce6535b544d84d6cd6f7ad8bd711c398938ae983b91a766d9"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.47"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fbf4db142a473a8d80c26bbf18454ed458bf8d26c8219c331daecfdbd079001"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "regex"
+version = "1.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f020237b6c8eed93db2e2cb53c00c60a8e1bc73da7d073199a1180401450218d"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ad8553b9b26413251cbf30e620595c7a41b3887f03da04579c0e6b0d6a06b4b2"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6f6ff9a378485b298a5286656da665ba74413d36db0979633275d2e708145d4"
+
+[[package]]
+name = "relative-path"
+version = "1.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba39f3699c378cd8970968dcbff9c43159ea4cfbd88d43c00b22f2ef10a435d2"
+
+[[package]]
+name = "rstest"
+version = "0.26.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f5a3193c063baaa2a95a33f03035c8a72b83d97a54916055ba22d35ed3839d49"
+dependencies = [
+ "futures-timer",
+ "futures-util",
+ "rstest_macros",
+]
+
+[[package]]
+name = "rstest_macros"
+version = "0.26.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c845311f0ff7951c5506121a9ad75aec44d083c31583b2ea5a30bcb0b0abba0"
+dependencies = [
+ "cfg-if",
+ "glob",
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "regex",
+ "relative-path",
+ "rustc_version",
+ "syn 2.0.119",
+ "unicode-ident",
+]
+
+[[package]]
+name = "rustc_version"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cfcb3a22ef46e85b45de6ee7e79d063319ebb6594faafcf1c225ea92ab6e9b92"
+dependencies = [
+ "semver",
+]
+
+[[package]]
+name = "semver"
+version = "1.0.28"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a7852d02fc848982e0c167ef163aaff9cd91dc640ba85e263cb1ce46fae51cd"
+
+[[package]]
+name = "serde_core"
+version = "1.0.229"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67dca2c9c51e58a4791a4b1ed58308b39c64224d349a935ab5039aa360942a48"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.229"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7a5d71263a5a7d47b41f6b3f06ba276f10cc18b0931f1799f710578e2309348"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 3.0.3",
+]
+
+[[package]]
+name = "slab"
+version = "0.4.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c790de23124f9ab44544d7ac05d60440adc586479ce501c1d6d7da3cd8c9cf5"
+
 [[package]]
 name = "statelet"
 version = "0.1.0"
+dependencies = [
+ "camino",
+ "rstest",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.119"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "872831b642d1a07999a962a351ed35b955ea2cfc8f3862091e2a240a84f17297"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "3.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "53e9bae58849f64dfa4f5d5ae372c8341f7305f82a3868709269343628b659a3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "toml_datetime"
+version = "1.1.1+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3165f65f62e28e0115a00b2ebdd37eb6f3b641855f9d636d3cd4103767159ad7"
+dependencies = [
+ "serde_core",
+]
+
+[[package]]
+name = "toml_edit"
+version = "0.25.13+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6975367e4d2ef766d86af01ffad14b622fecc8d4357a998fbc4deb6e9bacaf9b"
+dependencies = [
+ "indexmap",
+ "toml_datetime",
+ "toml_parser",
+ "winnow",
+]
+
+[[package]]
+name = "toml_parser"
+version = "1.1.3+spec-1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d38ac1cf9b95face32296c0a3ede1fdc270627c9d9c02a7274dd6d960dc4d56"
+dependencies = [
+ "winnow",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
+
+[[package]]
+name = "winnow"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23b97319f7b8343df12cc98938e5c3eb436064524c8d2b4e30a1d3a36eecdf81"
+dependencies = [
+ "memchr",
+]
diff --git a/Cargo.toml b/Cargo.toml
index 9d521dd..7005a98 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -79,3 +79,7 @@ missing_docs                        = "deny"
 
 [lints.rustdoc]
 missing_crate_level_docs            = "deny"
+
+[dev-dependencies]
+camino = "1.2.5"
+rstest = "0.26.1"
diff --git a/Makefile b/Makefile
index 31454e6..63ebae7 100644
--- a/Makefile
+++ b/Makefile
@@ -126,3 +126,14 @@ rust-audit: ## Audit the Rust workspace for known vulnerabilities
 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/docs/developers-guide.md b/docs/developers-guide.md
index c1026da..406d0a1 100644
--- a/docs/developers-guide.md
+++ b/docs/developers-guide.md
@@ -59,6 +59,31 @@ LLVM-compatible linker behaviour.
 Install `clang`, `lld`, `mold`, `python3`, and `cargo-audit` before running the
 full generated workflow locally on Linux.
 
+## Fast development builds
+
+`make dev-build` and `make dev-test` offer an opt-in, faster iteration loop
+for local debug work. `dev-build` compiles debug binaries and `dev-test` runs
+the test suite; both use the Cranelift codegen backend and the mold linker
+configured in `tools/dev-fast/config.toml`.
+
+The `DEV_FAST_CONFIG` variable names that fragment, defaulting to
+`tools/dev-fast/config.toml`, and both targets pass it to Cargo explicitly
+with `--config "$(DEV_FAST_CONFIG)"`. Cargo never auto-discovers this
+fragment; it takes effect only when a target invokes it directly, so other
+`make` targets are unaffected.
+
+Using the fragment requires a nightly toolchain, because the Cranelift
+codegen backend is unstable. On Linux it also requires the mold linker on
+`PATH`; the fragment gates the linker flag behind a `target_os = "linux"`
+`cfg` table, so other platforms fall back to their default linker.
+
+Cranelift configuration must never be copied into `.cargo/config.toml`.
+Cargo auto-discovers that file and applies it to every invocation, which
+would silently degrade release, coverage, and verification builds to the
+faster but less optimizing backend. Keep the fast-build configuration
+isolated in `tools/dev-fast/config.toml` and reach it only through
+`make dev-build` and `make dev-test`.
+
 ## Spelling policy
 
 The tracked `typos.toml` is generated from the shared estate dictionary and the
diff --git a/tests/dev_fast_contract.rs b/tests/dev_fast_contract.rs
new file mode 100644
index 0000000..6b9a441
--- /dev/null
+++ b/tests/dev_fast_contract.rs
@@ -0,0 +1,77 @@
+//! Contract tests for the opt-in dev-fast Make targets.
+//!
+//! `dev-build` and `dev-test` must honour the injectable `CARGO` variable
+//! and pass the dev-fast fragment to Cargo explicitly with `--config`,
+//! rather than relying on Cargo auto-discovering `.cargo/config.toml`.
+//! These tests parse `make --dry-run` output rather than running a real
+//! build, so they stay fast and do not require a nightly toolchain or the
+//! mold linker. Invoking `make` is process spawning, which Whitaker's
+//! capability-based filesystem rules do not constrain; only file access
+//! goes through `camino`.
+
+use std::{io, process::Command};
+
+use camino::{Utf8Path, Utf8PathBuf};
+use rstest::rstest;
+
+/// Returns the workspace root, derived from the manifest directory so the
+/// test works regardless of the runner's current directory.
+fn workspace_root() -> Utf8PathBuf { Utf8PathBuf::from(env!("CARGO_MANIFEST_DIR")) }
+
+/// Runs `make --dry-run <target> CARGO=probe-cargo` and returns its stdout.
+fn dry_run(target: &str) -> Result<String, io::Error> {
+    let output = Command::new("make")
+        .current_dir(workspace_root())
+        .args(["--dry-run", target, "CARGO=probe-cargo"])
+        .output()?;
+    Ok(String::from_utf8_lossy(&output.stdout).into_owned())
+}
+
+/// Locates `probe-cargo`, `--config`, and the dev-fast fragment marker on a
+/// recipe line, returning their byte offsets if all three are present.
+fn substitution_offsets(line: &str) -> Option<(usize, usize, usize)> {
+    let cargo = line.find("probe-cargo")?;
+    let config = line.find("--config")?;
+    let dev_fast = line.find("dev-fast")?;
+    Some((cargo, config, dev_fast))
+}
+
+#[rstest]
+#[case::dev_build("dev-build")]
+#[case::dev_test("dev-test")]
+fn dev_fast_target_substitutes_injected_cargo(#[case] target: &str) {
+    let stdout = dry_run(target).expect("make --dry-run should run");
+
+    let Some(recipe_line) = stdout.lines().find(|line| line.contains("probe-cargo")) else {
+        panic!("target {target} did not invoke the injected CARGO override:\n{stdout}");
+    };
+
+    let Some((cargo_pos, config_pos, dev_fast_pos)) = substitution_offsets(recipe_line) else {
+        panic!(
+            "target {target} recipe line is missing probe-cargo, --config, or a dev-fast \
+             reference:\n{recipe_line}"
+        );
+    };
+
+    assert!(
+        cargo_pos < config_pos && config_pos < dev_fast_pos,
+        "target {target} emitted an out-of-order command:\n{recipe_line}"
+    );
+}
+
+#[test]
+fn dev_fast_config_fragment_exists() {
+    let config_path: Utf8PathBuf = [
+        workspace_root().as_str(),
+        "tools",
+        "dev-fast",
+        "config.toml",
+    ]
+    .iter()
+    .collect();
+
+    assert!(
+        Utf8Path::new(&config_path).exists(),
+        "{config_path} must exist for the dev-fast targets to function"
+    );
+}
diff --git a/tools/dev-fast/config.toml b/tools/dev-fast/config.toml
new file mode 100644
index 0000000..01e7f89
--- /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 89d67e3..6eb34fc 100644
--- a/typos.local.toml
+++ b/typos.local.toml
@@ -13,6 +13,13 @@ accepted = []
 [patterns]
 # Preserve complete formal names while allowing Markdown line wrapping.
 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`",
   "Azure Architecture\\s+Center\\s+\\|\\s+Microsoft Learn",
   "GitHub\\s+Flavored\\s+Markdown",
 ]
diff --git a/typos.toml b/typos.toml
index 92a5a5b..fb0c159 100644
--- a/typos.toml
+++ b/typos.toml
@@ -31,10 +31,15 @@ extend-exclude = [
 locale = "en-gb"
 extend-ignore-re = [
     "(?s)```.*?```",
+    "-fuse-ld=mold",
     "Azure Architecture\\s+Center\\s+\\|\\s+Microsoft Learn",
+    "Cranelift \\+ mold",
+    "Cranelift and mold",
     "GitHub\\s+Flavored\\s+Markdown",
     "\\brust-analyzer\\b",
     "`[^`\\n]+`",
+    "`mold`",
+    "mold linker",
 ]
 
 [default.extend-words]