docs: record AK plan execution corrections; ignore CTest Testing/ dir

Plan updated with the Approx (not Catch::Approx) and
src/LibMTRSim/CMakeLists.txt corrections discovered during execution.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: imikejackson

.gitignore

@@ -2,3 +2,4 @@
 CLAUDE.md
 *.mat
 /docs/superpowers
+/Testing

docs/superpowers/plans/2026-06-01-milestone-ak.md

@@ -6,7 +6,11 @@
 
 **Architecture:** The heavy lifting is consolidated into a single reusable LibMTRSim entry point `simulateMTR()` that runs PGRF → orientation sampling → per-voxel assignment and returns results in **SIMPLNX z,y,x voxel order**. LibMTRSim Catch2 tests (in `tests/`) cover the numerics (deterministic helpers + a statistical end-to-end test reusing the ODF exemplar). The filter is a thin SIMPLNX wrapper (`MTRSimFilter` + `MTRSim` algorithm) whose tests (in `test/`) only verify the filter's value-add: parameter→params mapping, ODF-geometry→component reconstruction, array creation/types/names/1-based ids, seed handling, preflight validation, and the optional color array.
 
-**Tech Stack:** C++17, Eigen, simplnx filter framework, Catch2 v2 (note: `Catch::Approx`, not `Approx`), CMake, GitHub Actions.
+**Tech Stack:** C++17, Eigen, simplnx filter framework, Catch2 v2 (this repo uses the **bare `Approx`** matcher — `Approx` does NOT compile here), CMake, GitHub Actions.
+
+> **Correction applied during execution:** all Catch2 tests in this plan use
+> bare `Approx(...)`, not `Approx(...)`. The standalone LibMTRSim source
+> list is in `src/LibMTRSim/CMakeLists.txt` (not `LibMTRSim.cmake`).
 
 ---
 
@@ -69,7 +73,7 @@ simplnx checkout is at `/Users/mjackson/Workspace7/simplnx`):
 - `src/app/main.cpp` — call `simulateMTR()` instead of inline orchestration.
 - `MTRSimPlugin.cmake` — add `MTRSimDriver.{hpp,cpp}` to LibMTRSim sources;
   add `MTRSimFilter`/`MTRSim` to `FilterList`/`AlgorithmList`.
-- `LibMTRSim.cmake` — add `MTRSimDriver.{hpp,cpp}` to the standalone library.
+- `src/LibMTRSim/CMakeLists.txt` — add `MTRSimDriver.{hpp,cpp}` to the standalone library source/header lists.
 - `tests/CMakeLists.txt` — add `test_mtrsim_driver.cpp`.
 - `test/CMakeLists.txt` — add `MTRSimTest.cpp`.
 
@@ -194,13 +198,13 @@ TEST_CASE("buildUniformODF produces correct bin centres", "[mtrsim_driver]") {
   REQUIRE(uni.phi1Bins.size() == 72 * 36 * 72);
 
   // Uniform mass: every bin equal, sums to 1.
-  REQUIRE(uni.odfVal.sum() == Catch::Approx(1.0));
-  REQUIRE(uni.odfVal[0] == Catch::Approx(1.0 / (72.0 * 36.0 * 72.0)));
+  REQUIRE(uni.odfVal.sum() == Approx(1.0));
+  REQUIRE(uni.odfVal[0] == Approx(1.0 / (72.0 * 36.0 * 72.0)));
 
   // First bin centre: i1=iPHI=i2=0 -> all 0.5 * step.
-  REQUIRE(uni.phi1Bins[0] == Catch::Approx(0.5 * 2.0 * std::numbers::pi / 72.0));
-  REQUIRE(uni.phiBins[0] == Catch::Approx(0.5 * std::numbers::pi / 36.0));
-  REQUIRE(uni.phi2Bins[0] == Catch::Approx(0.5 * 2.0 * std::numbers::pi / 72.0));
+  REQUIRE(uni.phi1Bins[0] == Approx(0.5 * 2.0 * std::numbers::pi / 72.0));
+  REQUIRE(uni.phiBins[0] == Approx(0.5 * std::numbers::pi / 36.0));
+  REQUIRE(uni.phi2Bins[0] == Approx(0.5 * 2.0 * std::numbers::pi / 72.0));
 }
 ```
 
@@ -266,12 +270,12 @@ TEST_CASE("gridToODFComponent derives bin centres in radians and normalizes", "[
       mtrsim::gridToODFComponent(values, n1, nPHI, n2, 5.0, 5.0, 5.0);
 
   REQUIRE(c.odfVal.size() == n1 * nPHI * n2);
-  REQUIRE(c.odfVal.sum() == Catch::Approx(1.0)); // normalized
+  REQUIRE(c.odfVal.sum() == Approx(1.0)); // normalized
   // 5 deg step -> first bin centre 2.5 deg in radians.
   const double deg2rad = std::numbers::pi / 180.0;
-  REQUIRE(c.phi1Bins[0] == Catch::Approx(2.5 * deg2rad));
-  REQUIRE(c.phiBins[0] == Catch::Approx(2.5 * deg2rad));
-  REQUIRE(c.phi2Bins[0] == Catch::Approx(2.5 * deg2rad));
+  REQUIRE(c.phi1Bins[0] == Approx(2.5 * deg2rad));
+  REQUIRE(c.phiBins[0] == Approx(2.5 * deg2rad));
+  REQUIRE(c.phi2Bins[0] == Approx(2.5 * deg2rad));
 }
 ```
 
@@ -569,9 +573,9 @@ TEST_CASE("simulateMTR reproduces target volume fractions (statistical)", "[mtrs
   // Empirical volume fractions within tolerance of targets.
   std::array<int, 3> counts{0, 0, 0};
   for (int v : r.mtrIndex) { counts[v - 1]++; }
-  REQUIRE(static_cast<double>(counts[0]) / N == Catch::Approx(0.30).margin(0.05));
-  REQUIRE(static_cast<double>(counts[1]) / N == Catch::Approx(0.35).margin(0.05));
-  REQUIRE(static_cast<double>(counts[2]) / N == Catch::Approx(0.35).margin(0.05));
+  REQUIRE(static_cast<double>(counts[0]) / N == Approx(0.30).margin(0.05));
+  REQUIRE(static_cast<double>(counts[1]) / N == Approx(0.35).margin(0.05));
+  REQUIRE(static_cast<double>(counts[2]) / N == Approx(0.35).margin(0.05));
 
   // Euler ranges valid.
   for (double a : r.phi1) { REQUIRE(a >= 0.0); REQUIRE(a <= 2.0 * std::numbers::pi); }
@@ -1166,8 +1170,8 @@ TEST_CASE("MTRSimFilter: execute produces valid MTR ids + Eulers", "[MTRSim]")
     counts[v - 1]++;
   }
   const double n = static_cast<double>(ids.getNumberOfTuples());
-  REQUIRE(counts[0] / n == Catch::Approx(0.30).margin(0.06));
-  REQUIRE(counts[1] / n == Catch::Approx(0.35).margin(0.06));
+  REQUIRE(counts[0] / n == Approx(0.30).margin(0.06));
+  REQUIRE(counts[1] / n == Approx(0.35).margin(0.06));
 
   // Seed array recorded.
   auto& seedArr = ds.getDataRefAs<UInt64Array>(DataPath({"MTRSim SeedValue"}));