chore(compat.opencv): drop temp diagnostics + simplify now-tri-platform test

All three platforms build green, so remove the debug scaffolding and the
per-platform gating that only existed while opencv was Linux-only:
- descriptor: drop the trace()/diag_path/_dump_diagnostics on-disk-file
  scaffolding; on failure just log.error the build-log path (compat.openblas
  pattern). Refresh the stale header comment (macOS/Windows are done, not
  follow-ups).
- validate.yml: drop MCPP_VERBOSE=1 and the 'opencv build-log on failure' step.
- test project: collapse the three identical cfg(linux|macos|windows) dependency
  blocks into one unconditional [dependencies.compat]; drop roundtrip.cpp's
  #if defined(__linux__|__APPLE__|_WIN32) guard + #else no-op main.

Author: Sunrisepeak

.github/workflows/validate.yml

@@ -190,38 +190,11 @@ jobs:
         shell: bash
         env:
           MCPP_INDEX_MIRROR: GLOBAL
-          MCPP_VERBOSE: "1"   # TEMP: surface install() hook error detail for macOS debug
         run: |
           "$MCPP" --version
           # No `timeout` wrapper: absent on macOS runners; job-level timeout-minutes bounds it.
           "$MCPP" test --workspace
 
-      # TEMP diagnostic (remove before merge): xim's interface mode hides install()
-      # source-build output; on failure surface the opencv build log from the runner.
-      - name: opencv build-log on failure
-        if: failure()
-        shell: bash
-        run: |
-          # Cross-platform (linux/macOS/Windows-Git-Bash). The hook writes trace/diag
-          # under $RUNNER_TEMP (set on every runner OS); convert to a bash path on
-          # Windows. xim's interface mode hides install() output, so these files +
-          # the on-disk build log are the only window into a source-build failure.
-          d="$RUNNER_TEMP"
-          command -v cygpath >/dev/null 2>&1 && d="$(cygpath -u "$RUNNER_TEMP")"
-          echo "=== opencv install() trace ==="
-          cat "$d/ocv_trace.txt" 2>/dev/null || echo "(no trace)"
-          echo "=== opencv install() diag (build log / error, written by the hook) ==="
-          cat "$d/ocv_diag.txt" 2>/dev/null || echo "(no diag)"
-          echo "=== opencv build log(s) ==="
-          find . -name 'mcpp_opencv_build.log' 2>/dev/null | while read -r f; do
-            echo "--- $f ---"; cat "$f"; echo "--- end ---"
-          done || true
-          echo "=== opencv store tree (did cmake even run?) ==="
-          find . -path '*compat.opencv*4.13.0' -type d 2>/dev/null | head -1 | while read -r t; do ls -la "$t" 2>/dev/null | head; done || true
-          echo "=== compiler sanity ==="
-          command -v clang clang++ clang-cl gcc 2>/dev/null || true
-          xcrun --show-sdk-path 2>/dev/null || echo "(no xcrun)"
-
   # ── Exception: the public `imgui` C++23-module package (namespace "") ──
   # Not yet a workspace member: its package has an empty namespace (the builtin
   # default index), which a workspace member can't point at a local path the way

pkgs/c/compat.opencv.lua

@@ -11,10 +11,10 @@
 -- .agents/docs/2026-07-08-opencv-implementation-and-verification.md.
 --
 -- HOST-FREE / ecosystem-closed: the build uses ONLY ecosystem tools — xim:cmake,
--- xim:make, xim:gcc (declared build-deps) — never host cmake/make/gcc. Verified
--- offline under a network-isolated namespace (unshare -rn): zero downloads (gapi's
--- ADE fetch is killed by WITH_ADE=OFF); everything else is compiled from the
--- tarball's bundled 3rdparty/ (zlib + libpng + libjpeg-turbo built via BUILD_*=ON).
+-- xim:ninja + the per-OS compiler (declared build-deps) — never host
+-- cmake/ninja/compiler. Zero downloads at build time (gapi's ADE fetch is killed by
+-- WITH_ADE=OFF); everything else is compiled from the tarball's bundled 3rdparty/
+-- (zlib + libpng + libjpeg-turbo built via BUILD_*=ON).
 --
 -- MVP module set (this recipe): core + imgproc + imgcodecs (BUILD_LIST). This is a
 -- fixed, curated profile — OpenCV's WITH_*/BUILD_opencv_* toggles CANNOT be mcpp
@@ -23,19 +23,15 @@
 -- variants (calib3d/dnn/highgui/contrib) are separate follow-up packages, not
 -- per-consumer features. See the impl doc §"generic mcpp asks".
 --
--- ABI: OpenCV is C++, so its .a must be linked by the SAME C++ ABI (libstdc++) as
--- the consumer. install() builds with xim:gcc (gcc/libstdc++); the consumer must use
--- a gcc toolchain (the test project pins gcc@16.1.0). A clang/libc++ consumer would
--- ABI-clash — this is the toolchain-handshake gap noted in the impl doc.
+-- ABI: OpenCV is C++, so its static libs must be linked by the SAME C++ ABI as the
+-- consumer. install() therefore builds with the compiler whose ABI matches each
+-- platform's mcpp consumer — Linux gcc/libstdc++, macOS clang/libc++ (xim:llvm),
+-- Windows clang-cl/msvc-stl — selected in install() by os.host(). See that function
+-- for the per-platform toolchain + build-env details.
 --
--- Verified locally (mcpp 0.0.85, linux x86_64): build → link → run green
--- (opencv ok=1 core=4x4x3 gray(blue)=29 png_bytes=82 decoded=4x4). macOS follows the
--- same source-CMake path but is NOT yet verified — its default toolchain is clang
--- (libc++), which would ABI-clash with the gcc/libstdc++ .a this recipe builds
--- (the toolchain-handshake gap); making macOS use gcc, or building with the
--- consumer's compiler, is a follow-up. Windows (MSVC-ABI clang vs OpenCV CMake) is
--- likewise a follow-up. The test project is therefore LINUX-GATED for now
--- (gui-stack precedent): off-linux it is a clean no-op.
+-- All three platforms build → link → run green in CI (workspace linux/macOS/windows):
+-- the roundtrip test asserts core (4x4x3 BGR), imgproc (BGR->GRAY, blue luma 29) and
+-- imgcodecs (PNG encode/decode round-trip).
 package = {
     spec        = "1",
     namespace   = "compat",
@@ -152,14 +148,6 @@ local function sh_quote(value)
     return "'" .. tostring(value):gsub("'", "'\\''") .. "'"
 end
 
--- TEMP diagnostics path — cross-platform (no /tmp on Windows). GitHub sets
--- RUNNER_TEMP on every runner OS; the CI step cats these files after a failure.
-local function diag_path(name)
-    local base = os.getenv("RUNNER_TEMP") or os.getenv("TMPDIR")
-              or os.getenv("TEMP") or "/tmp"
-    return path.join(base, name)
-end
-
 -- Tools are invoked by BARE name, resolved off the install() PATH that xim sets up
 -- from the declared build-deps (the compat.openblas `CC=gcc` approach). This is
 -- deliberate: xim:cmake is glibc-dynamic, so exec'ing its raw binary by absolute
@@ -182,20 +170,9 @@ local function find_srcroot(version)
 end
 
 local function _install_impl()
-    -- [TEMP macOS debug] on-disk trace: the install() failure is invisible under
-    -- xim's interface mode; write progress to $HOME so CI can surface where it dies.
-    local _trbuf = ""
-    local function trace(s)
-        _trbuf = _trbuf .. tostring(s) .. "\n"
-        pcall(function() io.writefile(diag_path("ocv_trace.txt"), _trbuf) end)
-    end
-    trace("enter host=" .. tostring(os.host()))
     local version = pkginfo.version()
     local prefix  = pkginfo.install_dir()
     local srcroot = find_srcroot(version)
-    trace("version=" .. tostring(version))
-    trace("prefix=" .. tostring(prefix))
-    trace("srcroot=" .. tostring(srcroot) .. " isdir=" .. tostring(os.isdir(srcroot)))
 
     local jobs = (os.default_njob and os.default_njob()) or 4
 
@@ -316,14 +293,10 @@ local function _install_impl()
     -- compat.openblas). Then build out-of-source into ./_bld and install
     -- headers+libs back into prefix, which is now the cwd.
     os.tryrm(prefix)
-    trace("compiler gcc=" .. tostring(gcc) .. " gxx=" .. tostring(gxx) .. " isMac=" .. tostring(isMac))
-    trace("libenv=[" .. tostring(libenv) .. "]")
     os.mv(srcroot, prefix)
     os.cd(prefix)
-    trace("after mv+cd, prefix isdir=" .. tostring(os.isdir(prefix)))
 
     local logf = path.join(prefix, "mcpp_opencv_build.log")
-    trace("about to run cmake configure; logf=" .. tostring(logf))
 
     -- Value quoting differs by driver: the linux/macOS build runs through bash
     -- (sh_quote), Windows through cmd (see the exec branch) where single quotes
@@ -457,29 +430,15 @@ local function _install_impl()
     return true
 end
 
--- Surface the on-disk build log to the console on ANY failure. xim's interface
--- mode suppresses the cmake/make subprocess stdout, so without this a failed CI
--- build is invisible (the only symptom is the downstream "opencv2/core.hpp: No
--- such file"). Fires whether _install_impl raised or returned false.
--- xlings' interface mode swallows log.*/subprocess output, so write the failure
--- detail to a file the CI step can `cat` instead of logging it.
-local function _dump_diagnostics(raised, err)
-    local out = {}
-    if raised then table.insert(out, "install() raised: " .. tostring(err)) end
-    local logf = path.join(pkginfo.install_dir(), "mcpp_opencv_build.log")
-    if os.isfile(logf) then
-        table.insert(out, "---- mcpp_opencv_build.log ----\n" .. tostring(io.readfile(logf)))
-    else
-        table.insert(out, "no build log at " .. logf)
-        table.insert(out, "PATH=" .. tostring(os.getenv("PATH")))
-    end
-    pcall(function() io.writefile(diag_path("ocv_diag.txt"), table.concat(out, "\n") .. "\n") end)
-end
-
 function install()
     local ok, ret = pcall(_install_impl)
     if not ok or ret == false then
-        _dump_diagnostics(not ok, ret)
+        -- Point at the on-disk build log: xim's interface mode suppresses the
+        -- cmake subprocess stdout, so the log is the only record of a failed
+        -- source build (the compat.openblas pattern).
+        local logf = path.join(pkginfo.install_dir(), "mcpp_opencv_build.log")
+        log.error("compat.opencv install() failed (%s); see %s",
+                  ok and "returned false" or tostring(ret), logf)
         return false
     end
     return true

tests/examples/opencv/mcpp.toml

@@ -1,21 +1,15 @@
 # OpenCV test project. compat.opencv builds core+imgproc+imgcodecs from source via
 # its install() CMake hook (host-free: ecosystem xim:cmake/ninja + per-OS compiler)
-# and links the static module libs. All three platforms are wired, each with the
-# compiler whose ABI matches that platform's mcpp consumer: linux gcc/libstdc++,
-# macOS clang/libc++, Windows clang-cl/msvc-stl. Resolves compat.opencv from this
-# repo's own index.
+# and links the static module libs. Supported on all three platforms, each with the
+# compiler whose ABI matches that platform's mcpp consumer (linux gcc/libstdc++,
+# macOS clang/libc++, Windows clang-cl/msvc-stl), so the dependency is unconditional.
+# Resolves compat.opencv from this repo's own index.
 [package]
 name    = "opencv-tests"
 version = "0.1.0"
 
 [indices]
 compat = { path = "../../.." }
 
-[target.'cfg(linux)'.dependencies.compat]
-opencv = "4.13.0"
-
-[target.'cfg(macos)'.dependencies.compat]
-opencv = "4.13.0"
-
-[target.'cfg(windows)'.dependencies.compat]
+[dependencies.compat]
 opencv = "4.13.0"

tests/examples/opencv/tests/roundtrip.cpp

@@ -1,8 +1,6 @@
 // compat.opencv end-to-end assertion across core + imgproc + imgcodecs, linked
 // against the static libs built from source by the package's install() CMake hook.
-// Wired on linux/macOS/Windows (see mcpp.toml); on any other platform this is a
-// no-op main so `mcpp test --workspace` stays clean.
-#if defined(__linux__) || defined(__APPLE__) || defined(_WIN32)
+// Runs on all three supported platforms (linux/macOS/Windows).
 #include <opencv2/core.hpp>
 #include <opencv2/imgproc.hpp>
 #include <opencv2/imgcodecs.hpp>
@@ -28,6 +26,3 @@ int main() {
 
     return 0;
 }
-#else
-int main() { return 0; }  // compat.opencv is Linux-only for now; no-op elsewhere
-#endif