From f37ddcb8d70bd98f9dbe0460bea5eb745471f2ef Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 20:42:07 +0100
Subject: [PATCH 1/8] Align Dependabot coverage and add the dev-fast fragment

Bring `.github/dependabot.yml` to the estate baseline: one update
stanza per package ecosystem the repository uses, each labelled
`dependencies` plus its channel label, with GitHub Actions updates
batched into a single pull request via a wildcard group.

Add the opt-in dev-fast build fragment at
`tools/dev-fast/config.toml` (Cranelift codegen for the dev profile
and the mold linker on Linux) with `dev-build` and `dev-test` Make
targets that pass it explicitly via `--config`, and signpost the
workflow in `AGENTS.md`. Release, coverage, and verification builds
are unaffected: the fragment is never auto-discovered.
---
 .github/dependabot.yml     |  7 +++++++
 AGENTS.md                  |  9 +++++++++
 Makefile                   | 11 +++++++++++
 tools/dev-fast/config.toml | 30 ++++++++++++++++++++++++++++++
 4 files changed, 57 insertions(+)
 create mode 100644 tools/dev-fast/config.toml

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/Makefile b/Makefile
index 31454e6..aa71e9c 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/tools/dev-fast/config.toml b/tools/dev-fast/config.toml
new file mode 100644
index 0000000..75bfd76
--- /dev/null
+++ b/tools/dev-fast/config.toml
@@ -0,0 +1,30 @@
+# Canonical opt-in Cargo configuration fragment for accelerated local debug
+# builds.
+#
+# This file 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. Copy this fragment to
+# `tools/dev-fast/config.toml` and pass it 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 picks a single
+# rustflags source rather than merging them, and a `[target.*]` table
+# outranks the `[build]` table.
+
+[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"]

From 061cdc613400ea7e0289ba659d4cb077f7f5ab63 Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 22:16:13 +0100
Subject: [PATCH 2/8] Accept mold as the linker's name in the spelling config

The dev-fast rollout writes "mold" (the linker) into AGENTS.md and
the Makefile, and the en-GB-oxendict spelling gate reads it as a
misspelling of "mould", failing CI. Accept the word via the estate's
correction-to-itself pattern in `typos.local.toml`, and mirror it in
the generated dictionary so local runs agree with the regenerated
configuration.
---
 typos.local.toml | 3 +++
 typos.toml       | 1 +
 2 files changed, 4 insertions(+)

diff --git a/typos.local.toml b/typos.local.toml
index 89d67e3..47a7b9d 100644
--- a/typos.local.toml
+++ b/typos.local.toml
@@ -9,6 +9,9 @@ stems = []
 accepted = []
 
 [words.corrections]
+# "mold" names the linker (https://github.com/rui314/mold); it is not a
+# misspelling of "mould" in that context.
+mold = "mold"
 
 [patterns]
 # Preserve complete formal names while allowing Markdown line wrapping.
diff --git a/typos.toml b/typos.toml
index 92a5a5b..078ebff 100644
--- a/typos.toml
+++ b/typos.toml
@@ -1482,6 +1482,7 @@ extend-ignore-re = [
 "modularizers" = "modularizers"
 "modularizes" = "modularizes"
 "modularizing" = "modularizing"
+"mold" = "mold"
 "monetisable" = "monetizable"
 "monetisably" = "monetizably"
 "monetisation" = "monetization"

From cc6c2f330db1055e7aa2097e3975df4d7c65bfd2 Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 23:35:16 +0100
Subject: [PATCH 3/8] Scope the mold spelling exception to linker contexts

A blanket `mold = "mold"` correction disables detection of genuine
"mould" misspellings everywhere in the repository. Replace it with
pattern-scoped exemptions covering only the linker contexts the
dev-fast rollout introduced (`-fuse-ld=mold`, "mold linker",
"Cranelift + mold", "Cranelift and mold", and backticked `mold`),
and mirror them in the generated dictionary. Text such as "the bread
had mold growing on it" is flagged again.
---
 typos.local.toml | 10 +++++++---
 typos.toml       |  6 +++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/typos.local.toml b/typos.local.toml
index 47a7b9d..6eb34fc 100644
--- a/typos.local.toml
+++ b/typos.local.toml
@@ -9,13 +9,17 @@ stems = []
 accepted = []
 
 [words.corrections]
-# "mold" names the linker (https://github.com/rui314/mold); it is not a
-# misspelling of "mould" in that context.
-mold = "mold"
 
 [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 078ebff..303ab37 100644
--- a/typos.toml
+++ b/typos.toml
@@ -30,6 +30,11 @@ extend-exclude = [
 [default]
 locale = "en-gb"
 extend-ignore-re = [
+    "-fuse-ld=mold",
+    "mold linker",
+    "Cranelift \\+ mold",
+    "Cranelift and mold",
+    "`mold`",
     "(?s)```.*?```",
     "Azure Architecture\\s+Center\\s+\\|\\s+Microsoft Learn",
     "GitHub\\s+Flavored\\s+Markdown",
@@ -1482,7 +1487,6 @@ extend-ignore-re = [
 "modularizers" = "modularizers"
 "modularizes" = "modularizes"
 "modularizing" = "modularizing"
-"mold" = "mold"
 "monetisable" = "monetizable"
 "monetisably" = "monetizably"
 "monetisation" = "monetization"

From ec0eb8ff17649f95d2e1e9da5c4132e3022f00e7 Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 23:38:59 +0100
Subject: [PATCH 4/8] Refresh the dev-fast fragment's comments from canon

Estate review flagged two defects in the fragment's deployed
comments: a stale "copy this fragment" instruction that reads as
nonsense once the file is in place, and a mis-statement of Cargo's
rustflags semantics (Cargo joins the entries of every matching
`[target.*]` table; only the joined result takes precedence over
`[build].rustflags` rather than merging). Both are corrected in the
canonical source; take its bytes verbatim. No configuration key
changes.
---
 tools/dev-fast/config.toml | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/tools/dev-fast/config.toml b/tools/dev-fast/config.toml
index 75bfd76..01e7f89 100644
--- a/tools/dev-fast/config.toml
+++ b/tools/dev-fast/config.toml
@@ -1,18 +1,19 @@
 # Canonical opt-in Cargo configuration fragment for accelerated local debug
 # builds.
 #
-# This file 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. Copy this fragment to
-# `tools/dev-fast/config.toml` and pass it explicitly with
-# `cargo --config tools/dev-fast/config.toml ...` from `make dev-build` and
-# `make dev-test`.
+# 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 picks a single
-# rustflags source rather than merging them, and a `[target.*]` table
-# outranks the `[build]` table.
+# 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

From 84ce11b12ea3cd10b9071319047bd39dfb35bd67 Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 23:47:01 +0100
Subject: [PATCH 5/8] Route dev-fast targets through the injectable CARGO
 variable

`dev-build` and `dev-test` hard-coded `cargo` even though the Makefile
already exposes `CARGO ?= cargo` for every other target. Substitute
`$(CARGO)` so callers can point the dev-fast targets at an alternate
Cargo binary, matching the rest of the Makefile's convention.
---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index aa71e9c..63ebae7 100644
--- a/Makefile
+++ b/Makefile
@@ -133,7 +133,7 @@ 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
+	$(CARGO) --config "$(DEV_FAST_CONFIG)" build
 
 dev-test: ## Run tests with Cranelift and mold
-	cargo --config "$(DEV_FAST_CONFIG)" test
+	$(CARGO) --config "$(DEV_FAST_CONFIG)" test

From f0c40eef7adc915adc9d843880e5fa4e3b0cc5df Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 23:47:07 +0100
Subject: [PATCH 6/8] Add a contract test for the dev-fast Make targets

Prove that `dev-build` and `dev-test` honour the injected `CARGO`
variable and pass the dev-fast fragment via the explicit `--config`
mechanism, by parsing `make --dry-run ... CARGO=probe-cargo` output
and asserting `probe-cargo`, `--config`, and a dev-fast reference
appear in that order. Also assert `tools/dev-fast/config.toml`
exists, since both targets depend on it.

Parsing dry-run output keeps the test fast and avoids requiring a
nightly toolchain or the mold linker just to validate wiring.

Add `rstest` and `camino` as dev-dependencies: `rstest` parametrizes
the dev-build/dev-test cases, and `camino` builds the UTF-8 path used
to check the configuration fragment exists.
---
 Cargo.lock                 | 306 +++++++++++++++++++++++++++++++++++++
 Cargo.toml                 |   4 +
 tests/dev_fast_contract.rs |  77 ++++++++++
 3 files changed, 387 insertions(+)
 create mode 100644 tests/dev_fast_contract.rs

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/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"
+    );
+}

From 726a655dad57beee96a259319863cf887ffdcbe8 Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Thu, 13 Aug 2026 23:47:13 +0100
Subject: [PATCH 7/8] Document the dev-fast build targets in the developer
 guide

Add a "Fast development builds" section covering `dev-build` and
`dev-test`, the `DEV_FAST_CONFIG` variable and the explicit
`--config` mechanism it feeds (never auto-discovered), the nightly
toolchain and, on Linux, mold linker requirements, and the rule that
Cranelift configuration must never be copied into
`.cargo/config.toml`, which Cargo applies to release, coverage, and
verification builds alike.
---
 docs/developers-guide.md | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

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

From 1cf22424f863b9226fc356889cadcf78f463cc9d Mon Sep 17 00:00:00 2001
From: Payton McIntosh <pmcintosh@df12.net>
Date: Fri, 14 Aug 2026 00:58:55 +0100
Subject: [PATCH 8/8] Regenerate typos.toml to clear spelling-config drift

`make spelling-config` reported drift because the committed
`typos.toml` no longer matched what the pinned `typos-config-builder`
would produce from `typos.local.toml` plus the shared en-GB-oxendict
base. The likely cause is that earlier mechanical commits hand-edited
the mold-related entries (adding, then rescoping, them) directly in
`typos.toml`, in a form the builder orders differently from its own
output.

Regenerate with the pinned builder in write mode
(`typos-config-builder --repository .`, no `--check`). The resulting
diff only reorders the five entries the previous mold-scoping commits
touched (`-fuse-ld=mold`, `mold linker`, `Cranelift + mold`,
`Cranelift and mold`, `` `mold` ``) alongside the pre-existing
code-block, Azure, GitHub Flavored Markdown, rust-analyzer, and
backtick-span (`` `[^`\n]+` ``) exemptions. No pattern was added or
removed, and the backtick-span exemption was present both before and
after, so no `typos.local.toml` change is needed.

Verified the scoped mold exemption still holds in both directions
("the mold linker" passes, "the bread had mold growing" is still
flagged) and that `make spelling` now passes end to end.
---
 typos.toml | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/typos.toml b/typos.toml
index 303ab37..fb0c159 100644
--- a/typos.toml
+++ b/typos.toml
@@ -30,16 +30,16 @@ extend-exclude = [
 [default]
 locale = "en-gb"
 extend-ignore-re = [
+    "(?s)```.*?```",
     "-fuse-ld=mold",
-    "mold linker",
+    "Azure Architecture\\s+Center\\s+\\|\\s+Microsoft Learn",
     "Cranelift \\+ mold",
     "Cranelift and mold",
-    "`mold`",
-    "(?s)```.*?```",
-    "Azure Architecture\\s+Center\\s+\\|\\s+Microsoft Learn",
     "GitHub\\s+Flavored\\s+Markdown",
     "\\brust-analyzer\\b",
     "`[^`\\n]+`",
+    "`mold`",
+    "mold linker",
 ]
 
 [default.extend-words]