app: CRAP scores as a Lens sensor (ex_crap)

The coverage export from `test.coverage` now also feeds a `crap` sensor,
second in app's VERIFY_SENSORS. It runs with MIX_ENV=test so it reads the
export's own environment instead of compiling a dev build and scoring a
different module set, and it guards on the export's existence because
ex_crap silently falls back to 0% coverage when the file is missing.

Baseline at ex_crap's default threshold (30): 23 files, 139 functions,
worst score 20.00 (CoreComponents.table/1, 0% - unused upstream scaffold).
No offenders, so nothing to refactor or cover yet.

app/Makefile

@@ -3,7 +3,7 @@
 MISE_BIN ?= mise
 MISE_EXEC = $(MISE_BIN) exec --
 
-.PHONY: check precommit deps assets compile test test.coverage coverage format credo verify
+.PHONY: check precommit deps assets compile test test.coverage coverage crap format credo verify
 
 # Run all static analysis checks (no database required)
 check: credo format
@@ -48,6 +48,20 @@ coverage:
 	@test -f cover/default.coverdata || { echo "coverage: no exported coverage - run 'make test.coverage' first" >&2; exit 1; }
 	$(MISE_EXEC) mix test.coverage
 
+# Enforce CRAP scores (complexity x coverage) from the same export. No test run.
+# Runs in MIX_ENV=test because that is the environment the export came from:
+# running in dev would compile a second build and score against a different set
+# of modules. The guard is load-bearing for the same reason as `coverage`:
+# ex_crap falls back to 0% coverage when the export is missing, which would
+# report scores that are pessimistic instead of absent - a false failure is
+# less bad than a false pass, but neither is acceptable in the Lens pass.
+#
+# Threshold is ex_crap's default (30); whether to ratchet it down is an open
+# decision tracked in the "ratchets, deferred decisions, handoff practice" yak.
+crap:
+	@test -f cover/default.coverdata || { echo "crap: no exported coverage - run 'make test.coverage' first" >&2; exit 1; }
+	MIX_ENV=test $(MISE_EXEC) mix crap
+
 # Format code
 format:
 	$(MISE_EXEC) mix format
@@ -132,15 +146,16 @@ credo:
 #   - coverage   (yak: coverage floors + framework-glue exclusions policy)
 #                  WIRED below (test.coverage + coverage).
 #   - crap       (yak: CRAP scores with ex_crap (both apps))
+#                  WIRED below (crap); reuses the coverage export.
 #   - mutation   (yak: mutation testing with muex — a sensor, not a gate)
 #
 # Runtime note: the coverage sensor exports from a single suite run
-# (`test.coverage` -> `mix test --cover --export-coverage default`) that CRAP is
+# (`test.coverage` -> `mix test --cover --export-coverage default`) that CRAP
-# meant to reuse, instead of running the suite twice.
+# reuses, instead of running the suite twice.
 #
 # The suite runs FIRST, because it is what produces the coverage export the
 # sensors read; sensors still run cheapest-first among themselves.
-VERIFY_SENSORS := coverage
+VERIFY_SENSORS := coverage crap
 
 verify:
 	@echo "==> verify(app): suite (coverage exported), then sensors [$(VERIFY_SENSORS)]"

app/mix.exs

@@ -81,7 +81,8 @@ defmodule Firehose.MixProject do
       {:microprints,
        git: "https://gitea.apps.sustainabledelivery.com/QWAN/microprints-phoenix.git",
        branch: "main"},
-      {:credo, "~> 1.7", only: [:dev, :test], runtime: false}
+      {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
+      {:ex_crap, "~> 0.1.1", only: [:dev, :test], runtime: false}
     ]
   end
 

app/mix.lock

@@ -1,6 +1,7 @@
 %{
   "bandit": {:hex, :bandit, "1.13.1", "1ce25a7beb750ed3fa2e905962f1f9a679cb585f1da0ae45637d06e385ce2eae", [:mix], [{:hpax, "~> 1.1", [hex: :hpax, repo: "hexpm", optional: false]}, {:plug, "~> 1.18", [hex: :plug, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}, {:thousand_island, "~> 1.6", [hex: :thousand_island, repo: "hexpm", optional: false]}, {:websock, "~> 0.5", [hex: :websock, repo: "hexpm", optional: false]}], "hexpm", "39028f0b5a21404661410a6c19275060a9822c9dcca70b7c3e4e4fa50b11da58"},
   "bcrypt_elixir": {:hex, :bcrypt_elixir, "3.3.2", "d50091e3c9492d73e17fc1e1619a9b09d6a5ef99160eb4d736926fd475a16ca3", [:make, :mix], [{:comeonin, "~> 5.3", [hex: :comeonin, repo: "hexpm", optional: false]}, {:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "471be5151874ae7931911057d1467d908955f93554f7a6cd1b7d804cac8cef53"},
+  "boundary": {:hex, :boundary, "0.11.0", "56cff565b5565930765e02782281b022935fe8c2e1504543c8c1b44b85893b40", [:mix], [], "hexpm", "b9297a96ea14c0e63dbd77b8135e0d483f9c6f34ed1c9dee4b3fea82c596f55a"},
   "bunt": {:hex, :bunt, "1.0.0", "081c2c665f086849e6d57900292b3a161727ab40431219529f13c4ddcf3e7a44", [:mix], [], "hexpm", "dc5f86aa08a5f6fa6b8096f0735c4e76d54ae5c9fa2c143e5a1fc7c1cd9bb6b5"},
   "cc_precompiler": {:hex, :cc_precompiler, "0.1.11", "8c844d0b9fb98a3edea067f94f616b3f6b29b959b6b3bf25fee94ffe34364768", [:mix], [{:elixir_make, "~> 0.7", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "3427232caf0835f94680e5bcf082408a70b48ad68a5f5c0b02a3bea9f3a075b9"},
   "comeonin": {:hex, :comeonin, "5.5.1", "5113e5f3800799787de08a6e0db307133850e635d34e9fab23c70b6501669510", [:mix], [], "hexpm", "65aac8f19938145377cee73973f192c5645873dcf550a8a6b18187d17c13ccdb"},
@@ -13,6 +14,7 @@
   "ecto_sql": {:hex, :ecto_sql, "3.14.0", "06446ab8410d2f85bfbb80857ee224ab3b693700cbb38f6535d507449a627b2e", [:mix], [{:db_connection, "~> 2.9", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 3.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:ecto, "~> 3.14.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:myxql, "~> 0.8", [hex: :myxql, repo: "hexpm", optional: true]}, {:postgrex, "~> 0.19 or ~> 1.0", [hex: :postgrex, repo: "hexpm", optional: true]}, {:tds, "~> 2.1.1 or ~> 2.2", [hex: :tds, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4.0 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "f4d8d36faf294c9417b5a37ec7ac8217ee2abdef5fcf197ba690f361548d3949"},
   "elixir_make": {:hex, :elixir_make, "0.10.0", "16577e2583a79bb79237bbff349619ef5d80afffc07eac6e4faf0d00e2ddaf7d", [:mix], [], "hexpm", "dc1f09fb7fa68866b886abd5f0f3c83553b1a19a52359a899e92af1bb3b31982"},
   "esbuild": {:hex, :esbuild, "0.10.1", "32b44b468d2c6386b6bf9229617cbf51be025ce4380eacd383a8979cbb8327ef", [:mix], [{:jason, "~> 1.4", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "890f251330052dcacafa40c409769e7c42e3876fb0ae450707bde831be7b34ea"},
+  "ex_crap": {:hex, :ex_crap, "0.1.1", "c1770e7ce1843f304a27f5d32bfa867a340140e337684ee1929c770b2499f884", [:mix], [{:boundary, "~> 0.10", [hex: :boundary, repo: "hexpm", optional: false]}], "hexpm", "ada5d59bce442c1a8a987cb5328cbf4469fb56eb8d04641886f2199569a75b12"},
   "expo": {:hex, :expo, "1.1.1", "4202e1d2ca6e2b3b63e02f69cfe0a404f77702b041d02b58597c00992b601db5", [:mix], [], "hexpm", "5fb308b9cb359ae200b7e23d37c76978673aa1b06e2b3075d814ce12c5811640"},
   "file_system": {:hex, :file_system, "1.1.1", "31864f4685b0148f25bd3fbef2b1228457c0c89024ad67f7a81a3ffbc0bbad3a", [:mix], [], "hexpm", "7a15ff97dfe526aeefb090a7a9d3d03aa907e100e262a0f8f7746b78f8f87a5d"},
   "finch": {:hex, :finch, "0.24.0", "4022b6194e907b6d9b597c168001cac38e488a35fe36cef9d8297e3159782510", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.8", [hex: :mint, repo: "hexpm", optional: false]}, {:nimble_options, "~> 0.4 or ~> 1.0", [hex: :nimble_options, repo: "hexpm", optional: false]}, {:nimble_pool, "~> 1.1", [hex: :nimble_pool, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "33ba40069c3587c2f99f9125b766e19dad87d6d54be3c6961db2304df04cef00"},